From 8187a3b5cd1fb2678d6968edc9b3ea7b5eb9eca5 Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 11:42:28 +0200
Subject: [PATCH 01/22] docs, bugs: the census figure and the error-9 note
 re-measured on BETA 995

---
 BUGS-TO-REPORT.md                              | 2 +-
 docs/Documentation/Tools.md                    | 2 +-
 docs/Reference/Default/VBA/ErrObject/Number.md | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/BUGS-TO-REPORT.md b/BUGS-TO-REPORT.md
index 7493e337..48dfa992 100644
--- a/BUGS-TO-REPORT.md
+++ b/BUGS-TO-REPORT.md
@@ -835,7 +835,7 @@ dialog calls after its folder picker --- and `root.saveProjectAs()` over DevTool
 
 ## An out-of-range index raises `&H8002000B` or `&H80004005`, not VBA's error 9
 
-**Build:** BETA 983 --- the IDE and a compiled EXE alike
+**Build:** BETA 995 in the IDE; BETA 983 in the IDE and a compiled EXE alike
 **Severity:** VBA code that handles `Err.Number = 9` does not recognise the error, with no
 diagnostic.
 
diff --git a/docs/Documentation/Tools.md b/docs/Documentation/Tools.md
index 755efa6e..3c946d88 100644
--- a/docs/Documentation/Tools.md
+++ b/docs/Documentation/Tools.md
@@ -1171,7 +1171,7 @@ Exit codes: **0** the probe project and the key were written, **2** a refused co
 
 Reports, for every attribute the twinBASIC packages use, **which enclosing construct and which kind of declaration it decorates**. It exports each package of an IDE install with the compiler's own `export` verb, scans the `.twin` sources, and writes a Markdown or JSON report. No arguments are needed: it finds the newest `twinBASIC_IDE_BETA_*` the same way [`tbbuild.mjs`](#tbbuild) does, caches the export under the build number, and reuses it on later runs. It is not part of the site build and nothing calls it during one.
 
-Against BETA 983 that is 661 files, 9,701 attribute sites and 55 distinct attributes.
+Against BETA 995 that is 661 files, 9,713 attribute sites and 55 distinct attributes.
 
 **A census is evidence, not applicability.** It says where an attribute *is* used, never where it *may* be used, and the two differ in both directions. The packages contain no use of `[Hidden]` on a whole **Class**, yet the compiler accepts one; they contain many on **Class** and **Interface** members, and the compiler refuses the same attribute on the **Interface** lines inside a **CoClass**. Neither fact is reachable from the other tool, so pair this with [`gen_attribute_probes.mjs`](#gen-attribute-probes) and [`tbbuild.mjs`](#tbbuild), which ask the compiler directly.
 
diff --git a/docs/Reference/Default/VBA/ErrObject/Number.md b/docs/Reference/Default/VBA/ErrObject/Number.md
index 87a733fe..be85ec17 100644
--- a/docs/Reference/Default/VBA/ErrObject/Number.md
+++ b/docs/Reference/Default/VBA/ErrObject/Number.md
@@ -26,7 +26,7 @@ Err.Raise Number:=vbObjectError + 1051, Source:="SomeClass"
 {: #error-numbers-that-differ-from-vba }
 
 > [!NOTE]
-> As of BETA 983, twinBASIC does not raise error 9, *Subscript out of range*, for an array index that is out of range or for a **Collection** member that does not exist. VBA's documentation gives error 9 for each case below; twinBASIC raises a different number.
+> As of BETA 995, twinBASIC does not raise error 9, *Subscript out of range*, for an array index that is out of range or for a **Collection** member that does not exist. VBA's documentation gives error 9 for each case below; twinBASIC raises a different number.
 
 | Access | VBA | twinBASIC |
 |---|---|---|

From 549ee9f2640d427b5b111b6f3b36d739a442fb5a Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 11:47:11 +0200
Subject: [PATCH 02/22] docs: Attributes.md's applicability notes and three
 tbIDE notes re-measured on BETA 995

---
 docs/Reference/Attributes.md                  | 36 +++++++++----------
 docs/Reference/Built-In/tbIDE/HtmlElement.md  |  2 +-
 .../Built-In/tbIDE/HtmlElementProperties.md   |  2 +-
 .../Built-In/tbIDE/KeyboardShortcuts.md       |  4 +--
 4 files changed, 21 insertions(+), 23 deletions(-)

diff --git a/docs/Reference/Attributes.md b/docs/Reference/Attributes.md
index ce8c23e6..cf238d20 100644
--- a/docs/Reference/Attributes.md
+++ b/docs/Reference/Attributes.md
@@ -179,14 +179,13 @@ Public Declare Function GetTickCount Lib "kernel32" () As Long
 ```
 
 <!-- Applicability from the attribute sweep (scripts/sweep_attributes.mjs) against
-     BETA 987, each of the bare form, (True) and (False): accepted on a Public
+     BETA 995, each of the bare form, (True) and (False): accepted on a Public
      Declare Function, a Public Declare Sub, a Private Declare Function, a
      Declare PtrSafe Function and a DeclareWide Function in a module, and on a
      Public and a Private Const in a module; refused with TB5155 on a Sub,
      Function or Property Get in a module (Public, Private, Static and generic)
      and on a module variable, and with TB5182 on a Declare or a Const in a
-     class. Earlier probes X05, X06 and X16 (BETA 983) had tried only a Sub
-     and a Const. A clean build
+     class. A clean build
      shows the compiler accepts the attribute, not what it makes a built file
      contain, and no package or sample uses it, so its effect is not
      established. -->
@@ -602,24 +601,22 @@ Hides the declaration from certain IntelliSense and other lists. It applies to a
 > [!NOTE]
 > A **CoClass** can only be hidden whole. Its body holds nothing but **Interface** lines, and the attribute is refused there with TB5155 --- unlike [**Default**](#default) and [**Source**](#source), which are interface-line attributes. It is likewise refused on an **Enum** or [**Type**](Type) declaration, on a **Type** member, and on a procedure parameter. An individual **Enum** *member* is hidden the same way: the **Encoding** constants of [**Open**](Open) are marked `[Hidden, Restricted]`.
 
-<!-- Applicability from scripts/census_attributes.mjs over BETA 983 (269 sites)
-     plus one probe per target via gen_attribute_probes.mjs + tbbuild.mjs.
-     Census: Module DeclareWide 158, Module Const 50, Class Property 18 / Sub 9
+<!-- Applicability from scripts/census_attributes.mjs over BETA 995 (270 sites)
+     plus the attribute sweep (scripts/sweep_attributes.mjs), BETA 995.
+     Census: Module DeclareWide 159, Module Const 50, Class Property 18 / Sub 9
      / variable 7 / Event 1, Interface Property 10 / Function 6 / Sub 3, whole
      CoClass 3, whole Module 2, whole Interface 2.
-     Probed clean: all four whole types, the Class and Interface members above,
-     a Private Const in a Class, a Module Sub/variable/Const and a Declare.
+     Swept clean: all four whole types, every procedure, variable, Const,
+     Event and Declare site in a Class, Module or Interface.
      The Enum member (the [Hidden, Restricted] shape Core/Open documents) also
-     compiled, but that proves nothing: the attribute sweep (BETA 987) found an
-     Enum body accepts ANY attribute on its own line, [ClassId("guid")] and
-     [Hidden(True)] included, and refuses every attribute written inline.
-     Core/Open's Encoding constants are the only evidence for it.
-     Probed TB5155: the Interface line inside a CoClass, a whole Enum, a whole
-     Type. TB5182: a Type member, a procedure parameter.
+     compiles, but that proves nothing: an Enum body accepts ANY attribute on
+     its own line, an attribute that does not exist included, so the sweep
+     voids that site. Core/Open's Encoding constants are the only evidence.
+     Swept TB5155: the Interface line inside a CoClass, a whole Enum, a whole
+     Type, a Delegate, Implements and Inherits. TB5182: a Type member, a
+     procedure parameter.
      Note the census finds NO use on a whole Class, though the probe compiles
-     and this entry has always claimed it -- which is the census/probe split
-     working: absence of a use is not absence of applicability.
-     This entry named only Class, CoClass and Interface until then. -->
+     -- absence of a use is not absence of applicability. -->
 
 
 ## IdeButton  (String)
@@ -679,8 +676,9 @@ Elsewhere in the project, `Honk` is callable on a **CCar** and `Diagnostics` is
 
 For an overview of the `Implements ... Via` mechanism itself, see [Implements Via for basic inheritance](../../Features/Language/Inheritance#implements-via-for-basic-inheritance).
 
-<!-- Applicability by probe, BETA 983; no package or sample uses this
-     attribute. Accepted on `Implements <Class> Via <field> = <expr>` and on
+<!-- Applicability by probe, BETA 983, and by the attribute sweep, BETA 995,
+     which gives the same answers; no package or sample uses this
+     attribute. The control and the effect below were measured on 983. Accepted on `Implements <Class> Via <field> = <expr>` and on
      `Implements <Interface> Via <Class>`; rejected on a plain Implements
      statement (TB5155), on the Class (TB5182), on the Interface (TB5182), on
      an Inherits statement (TB5155) and on an Interface line in a CoClass
diff --git a/docs/Reference/Built-In/tbIDE/HtmlElement.md b/docs/Reference/Built-In/tbIDE/HtmlElement.md
index 935bd7da..2a2524af 100644
--- a/docs/Reference/Built-In/tbIDE/HtmlElement.md
+++ b/docs/Reference/Built-In/tbIDE/HtmlElement.md
@@ -100,7 +100,7 @@ raiseEvent(eventName, event, stopPropagation, ...customData)
 --- pass an event name (any string), the DOM `event` object, a boolean controlling propagation, and any number of trailing custom-data values. The addin then registers a listener with the same event name through **AddEventListener**, and the custom-data values arrive on the [**HtmlEventProperties**](HtmlEventProperties) as `eventInfo.customData0`, `eventInfo.customData1`, … (numerically indexed from zero). This pattern is used heavily in sample 13 (listview) and sample 15 (Global Search) to attach handlers to per-item buttons rendered inside a listview's HTML.
 
 > [!NOTE]
-> **raiseEvent** works only inside a `"listview"` or `"virtuallistview"` widget, or inside a widget added with [**CodeEditor.AddMonacoWidget**](CodeEditor#addmonacowidget). It passes the event to the nearest enclosing widget: in a list view, register the listener on the list view object, `.Properties.listview.AddEventListener("name", ...)`, as sample 15 does; in a code-editor widget, on the widget's own element. In plain tool-window HTML there is no such widget, and in BETA 983 **raiseEvent** throws a `TypeError` in the IDE's page and the listener is not called.
+> **raiseEvent** works only inside a `"listview"` or `"virtuallistview"` widget, or inside a widget added with [**CodeEditor.AddMonacoWidget**](CodeEditor#addmonacowidget). It passes the event to the nearest enclosing widget: in a list view, register the listener on the list view object, `.Properties.listview.AddEventListener("name", ...)`, as sample 15 does; in a code-editor widget, on the widget's own element. In plain tool-window HTML there is no such widget, and in BETA 995 **raiseEvent** throws a `TypeError` in the IDE's page and the listener is not called.
 >
 > From plain HTML, an inline handler can call the listener itself. **AddEventListener** stores a listener for a name that is not one of the element's DOM events on the element, under that name, so an inline `onclick='this.parentNode.myEvent(event)'` calls the listener its parent registered as `"myEvent"`, and `eventInfo.target.id` names the element clicked.
 
diff --git a/docs/Reference/Built-In/tbIDE/HtmlElementProperties.md b/docs/Reference/Built-In/tbIDE/HtmlElementProperties.md
index a41318fe..43b45886 100644
--- a/docs/Reference/Built-In/tbIDE/HtmlElementProperties.md
+++ b/docs/Reference/Built-In/tbIDE/HtmlElementProperties.md
@@ -25,7 +25,7 @@ The shorthand reads at run time as a chain of `Item("name")` lookups against the
 > This interface is **`[COMExtensible(True)]`**. Property names are resolved against the live DOM element at run time, not declared statically on the interface. The compiler does not validate names --- a typo (`.innerTxt = "..."` instead of `.innerText = "..."`) fails silently or throws at run time. The accepted set is **every DOM property of the underlying tag**, plus any custom-widget extensions; the reference does not enumerate it.
 
 > [!NOTE]
-> A property whose name starts with `on` is ignored. In BETA 983, `.onclick = "..."` sets nothing, and the call returns without an error. Register a listener with [**HtmlElement.AddEventListener**](HtmlElement#addeventlistener) instead.
+> A property whose name starts with `on` is ignored. In BETA 995, `.onclick = "..."` sets nothing, and the call returns without an error. Register a listener with [**HtmlElement.AddEventListener**](HtmlElement#addeventlistener) instead.
 
 > [!IMPORTANT]
 > Text set as `innerHTML` is parsed as HTML, and an inline event handler in it runs as script of the IDE's own page, with access to everything that page's script can reach. An `<img>` whose image fails to load runs its `onerror` handler as soon as it is set, with nothing clicked. Escape any text that comes from a file, a project or the user before it goes into `innerHTML`, or set `innerText` instead.
diff --git a/docs/Reference/Built-In/tbIDE/KeyboardShortcuts.md b/docs/Reference/Built-In/tbIDE/KeyboardShortcuts.md
index 2e2e52dc..e7cb4ede 100644
--- a/docs/Reference/Built-In/tbIDE/KeyboardShortcuts.md
+++ b/docs/Reference/Built-In/tbIDE/KeyboardShortcuts.md
@@ -30,7 +30,7 @@ End Sub
 The shortcut fires when the key is released, wherever the focus is in the IDE's window --- in the code editor, in the DEBUG CONSOLE, or on nothing at all --- except while a dialog or the rename box is open. If the IDE has a command of its own on the same key, that command runs as well: F1, for one, also expands or collapses the signature help while it is showing. Shift+F12 has no command in the IDE's default keymap.
 
 > [!NOTE]
-> In BETA 983, a shortcut that includes `{CTRL}` or `{ALT}` does not fire when the user presses it. The IDE matches an add-in's shortcut when the key is released, against a press of the same key less than half a second earlier, and it does not record a key pressed while Ctrl or Alt is held down. Such a shortcut fires only if the same key was also pressed on its own within that half second. Use a function key, alone or with `{SHIFT}`.
+> In BETA 995, a shortcut that includes `{CTRL}` or `{ALT}` does not fire when the user presses it. The IDE matches an add-in's shortcut when the key is released, against a press of the same key less than half a second earlier, and it does not record a key pressed while Ctrl or Alt is held down. Such a shortcut fires only if the same key was also pressed on its own within that half second. Use a function key, alone or with `{SHIFT}`.
 
 ## Methods
 
@@ -44,7 +44,7 @@ Syntax: *keyboardShortcuts*.**Add** *keyString*, *Callback*
 *keyString*
 : *required* A **String** naming the key, after any of the prefixes `{CTRL}`, `{SHIFT}` and `{ALT}`. The prefixes must come in that order: the IDE builds the string it compares in that order, so `"{SHIFT}{CTRL}d"` never matches. **Add** converts the string to lower case and removes its spaces, so `"{SHIFT}F12"` and `"{shift} f12"` are the same shortcut. A letter names the key that types it on a US keyboard, whatever the active layout. Any other key is named as the browser names it --- `f1`, `enter`, `escape` --- and a key pressed with Shift by the character it types, so Shift+1 is `"{SHIFT}!"` on a US layout.
 
-  | Example            | Combination       | Fires in BETA 983 |
+  | Example            | Combination       | Fires in BETA 995 |
   |--------------------|-------------------|-------------------|
   | `"f1"`             | F1                | yes               |
   | `"{SHIFT}F12"`     | Shift + F12       | yes               |

From 756c39654373c7d89d07441d82b8ab81b601f907 Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 11:58:00 +0200
Subject: [PATCH 03/22] docs, bugs: Forms-by-index crash still on BETA 995; it
 needs a variable As Form

---
 BUGS-TO-REPORT.md                         | 11 +++++++----
 docs/Reference/Default/VB/Global/index.md |  2 +-
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/BUGS-TO-REPORT.md b/BUGS-TO-REPORT.md
index 48dfa992..98f495f1 100644
--- a/BUGS-TO-REPORT.md
+++ b/BUGS-TO-REPORT.md
@@ -867,7 +867,7 @@ varies between runs --- *Unspecified error* in one, *Automation error* in anothe
 
 ## Reading `Forms` by index returns a broken reference, and the process then crashes
 
-**Build:** BETA 983 --- the IDE and a compiled EXE alike
+**Build:** BETA 995 as a compiled EXE; BETA 983 in the IDE and a compiled EXE alike
 **Severity:** crash (`0xC0000005`), from a form of access the documentation shows.
 
 With one form loaded (`Load Form1`):
@@ -877,9 +877,12 @@ Dim s As String
 s = Forms(0).Name        ' s is "", and the process later dies with 0xC0000005
 ```
 
-`Set f = Forms(0)` followed by `f.Name` does the same, and so does `s = Forms(n).Name` with
-`n` a variable. Inside `For k = 0 To Forms.Count - 1`, `Set f = Forms(k)` corrupts the loop
-variable: `k` read 0, 0, 0, then 8195702.
+`Set f = Forms(0)` followed by `f.Name` does the same when `f` is declared `As Form`, and so
+does `s = Forms(n).Name` with `n` a variable. Inside `For k = 0 To Forms.Count - 1`,
+`Set f = Forms(k)` with `f` declared `As Form` corrupts the loop variable: `k` read 0, 0, 0,
+then 8195702. With three forms loaded, BETA 995 and 983 alike log `k=0` twice, then a
+corrupted string, and exit `0xC0000005`. With `f` declared `As Form1` or `As Object`, the same
+code returns the form and exits 0.
 
 **What does not reproduce it:** `n = 0: Set f = Forms(n)` outside a loop returns the form
 (`f.Name` is `Form1`) and the program exits 0; `For Each f In Forms` and `Unload Forms(i)` work;
diff --git a/docs/Reference/Default/VB/Global/index.md b/docs/Reference/Default/VB/Global/index.md
index 9f15169f..bbd425f1 100644
--- a/docs/Reference/Default/VB/Global/index.md
+++ b/docs/Reference/Default/VB/Global/index.md
@@ -44,7 +44,7 @@ These properties are cached references --- repeated reads return the same object
 - **Forms.Add(** *Name* **)** --- creates a new instance of the form class named *Name*, adds it to the collection, and returns the new [**Form**](../Form/). The form is loaded but not shown.
 
 > [!WARNING]
-> In BETA 983, taking a form out of **Forms** by index can crash the program. `Forms(0).Name` returns an empty string, and so does the **Name** of a form taken with `Set f = Forms(0)`; the program then stops with an access violation (`0xC0000005`), in the IDE and as a compiled program alike. Inside a `For` loop, `Set f = Forms(k)` also changes the loop variable. `For Each` over **Forms**, and `Unload Forms(i)`, both work: reach a loaded form with `For Each`, or by its class name.
+> In BETA 995, taking a form out of **Forms** by index can crash the program. `Forms(0).Name` returns an empty string, and so does the **Name** of a form taken with `Set f = Forms(0)` when `f` is declared `As Form`; the program then stops with an access violation (`0xC0000005`), in the IDE and as a compiled program alike. Inside a `For` loop, `Set f = Forms(k)` also changes the loop variable. `For Each` over **Forms**, and `Unload Forms(i)`, both work, and so does `Set f = Forms(k)` when `f` is declared `As Object` or as the form's own class: reach a loaded form that way, with `For Each`, or by its class name.
 
 The collection also supports `For Each` enumeration:
 

From 26593a95e1a084cf8599df11dfd58e0bb6827f8a Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 12:34:35 +0200
Subject: [PATCH 04/22] scripts: the lane runner shared; ide-test.bat runs IDE
 scenarios, Export Project first

---
 README.md                                   |   3 +-
 WIP.md                                      |   7 +
 docs/Documentation/Tools.md                 |  41 +-
 ide-test.bat                                |  31 ++
 scripts/addin_test.mjs                      | 400 ++-----------------
 scripts/check_cli.mjs                       |  23 ++
 scripts/ide_test.mjs                        |  49 +++
 scripts/lib/lane-runner.mjs                 | 417 ++++++++++++++++++++
 test/README.md                              |   3 +
 test/addin/scenario.mjs                     |   5 +-
 test/ide/export.test.mjs                    | 108 +++++
 test/ide/lanes.mjs                          |  18 +
 test/ide/probes/export/Settings             |  61 +++
 test/ide/probes/export/Sources/Startup.twin |   5 +
 14 files changed, 788 insertions(+), 383 deletions(-)
 create mode 100644 ide-test.bat
 create mode 100644 scripts/ide_test.mjs
 create mode 100644 scripts/lib/lane-runner.mjs
 create mode 100644 test/ide/export.test.mjs
 create mode 100644 test/ide/lanes.mjs
 create mode 100644 test/ide/probes/export/Settings
 create mode 100644 test/ide/probes/export/Sources/Startup.twin

diff --git a/README.md b/README.md
index 2db71111..8cd0773f 100644
--- a/README.md
+++ b/README.md
@@ -31,9 +31,10 @@ test.bat        # the gates that test the toolchain itself
 book.bat        # renders the PDF book; run build.bat first
 examples.bat    # compiles the twinBASIC code samples in the pages (Windows + a twinBASIC install)
 addin-test.bat  # tests IDE add-ins by operating an IDE (Windows + a twinBASIC install)
+ide-test.bat    # tests the IDE itself by operating it (Windows + a twinBASIC install)
 ```
 
-A clean `build.bat && check.bat` is the bar for "ready to commit"; add `test.bat` when the change touched anything outside `docs/`. Each wrapper names the gates it runs, in order, on [Tools and Scripts](https://docs.twinbasic.com/Documentation/Development/Tools). On Linux or macOS, run the `node` command inside each batch file directly --- they are thin wrappers. `examples.bat` and `addin-test.bat` are the exceptions to both: they drive the twinBASIC IDE, so they are Windows-only and deliberately outside every gate and outside CI.
+A clean `build.bat && check.bat` is the bar for "ready to commit"; add `test.bat` when the change touched anything outside `docs/`. Each wrapper names the gates it runs, in order, on [Tools and Scripts](https://docs.twinbasic.com/Documentation/Development/Tools). On Linux or macOS, run the `node` command inside each batch file directly --- they are thin wrappers. `examples.bat`, `addin-test.bat` and `ide-test.bat` are the exceptions to both: they drive the twinBASIC IDE, so they are Windows-only and deliberately outside every gate and outside CI.
 
 Where to read more:
 
diff --git a/WIP.md b/WIP.md
index ac02e83f..9b896209 100644
--- a/WIP.md
+++ b/WIP.md
@@ -164,6 +164,12 @@ addin-test.bat --only sample15     # one lane; --port N moves the lanes' ports
 - **A test never opens a real browser.** Every IDE the harness starts has `TB_ADDIN_TEST=1`, and an add-in under test prints `open <url>` to the DEBUG CONSOLE instead. Never start a test IDE with the variable removed unless its add-in opens nothing either way.
 - **Name in `lanes.mjs` every application an add-in under test passes to `SaveSetting`**, or its settings stay changed after the run: `SaveSetting` writes the key the user's own copy of the add-in reads.
 
+**Testing the IDE itself** (the debugger, Export Project, the Packages dialog) is
+`ide-test.bat`, the same runner (`scripts/lib/lane-runner.mjs`) over `test/ide/lanes.mjs`,
+with base port 9660 against the add-in runner's 9560. Every rule above applies to it
+unchanged: the private `APPDATA`, `TB_ADDIN_TEST=1`, and ending an IDE by its pid. Its
+scenario files import `scenario` from `test/addin/scenario.mjs`.
+
 ## Authoring a page
 
 **[WIP.Authoring.md](WIP.Authoring.md) is required reading before writing or
@@ -459,6 +465,7 @@ Why the report separates the wedged task from the merely blocked ones, and why
 
 - `examples.bat` — compiles the documentation's own twinBASIC code samples, every `tb` fence marked `check_build`, and reports the ones the compiler refuses against the line in the page they came from. Needs a twinBASIC install and Windows, so it is outside every gate and outside CI; ~120 s over the 1,136 samples marked. Two modes need no compiler at all: `--census` classifies every fence and says how many classifiable ones are still unmarked, and `--report <survey.json>` groups a saved `--propose --json` survey by diagnostic, section and unresolved name. `--propose` itself does compile. See [Compiling the reference's own code samples](#compiling-the-references-own-code-samples) and [WIP.ExamplesBuild.md](WIP.ExamplesBuild.md).
 - `addin-test.bat` — tests IDE add-ins by operating an IDE: every lane in `test/addin/lanes.mjs` builds the add-ins it tests into a private copy of the install, opens a project and checks what the add-in does. Outside every gate and outside CI for the same reasons as `examples.bat`; ~140 s for the ten lanes today: Samples 10 and 15, and the eight probe lanes behind Stage 2's answers in [WIP.HelpAddin.md](WIP.HelpAddin.md). Exit 0 every lane passed and the registry is as it was found, 1 a lane failed, 2 the harness failed, 3 the registry or a work folder was not put back. See [Driving the twinBASIC compiler](#driving-the-twinbasic-compiler) for its rules.
+- `ide-test.bat` --- the same runner for scenarios that operate the IDE itself rather than an add-in: every lane in `test/ide/lanes.mjs`, base port 9660. Same exit codes, same standing outside every gate and outside CI, same rules.
 
 Three generators sit outside that loop and produce committed artifacts rather than build output — none runs during a build, and none is needed for one. `python scripts/build_fonts.py` rebuilds the subset webfaces under `docs/assets/fonts/` and needs a network connection; `node scripts/build_dot_metrics.mjs` regenerates `builder/inter-metrics.json` from those webfaces and needs only a browser. See [Typography](#typography). `node scripts/build_package_api.mjs` regenerates `builder/package-api.json`, the packages' declared API that the build's symbol index (`tB/symbols.json`, for the IDE help add-in) is annotated from; it needs a twinBASIC install, so **run it when the reference is re-indexed against a newer build** and commit it with the pages. See [WIP.HelpAddin.md, Stage 3](WIP.HelpAddin.md#stage-3-the-symbol-index-generated-by-the-docs-build).
 
diff --git a/docs/Documentation/Tools.md b/docs/Documentation/Tools.md
index 3c946d88..de497111 100644
--- a/docs/Documentation/Tools.md
+++ b/docs/Documentation/Tools.md
@@ -8,14 +8,14 @@ permalink: /Documentation/Development/Tools
 # Tools and Scripts
 {: .no_toc }
 
-One-line-per-tool reference for every executable in the documentation repository: the seven Windows batch wrappers at the repository root, the Node and Python scripts under `scripts/` (cross-platform except for [`tbbuild.mjs`](#tbbuild), which drives the twinBASIC IDE), the `tbdocs` orchestrator and its CLI flags, and the PDF render driver. If you are looking for the day-to-day workflow rather than a cheat sheet, the [Building and Deployment](Building) page is the gentler read; if you are modifying the build pipeline itself, the [tbdocs Internals](Builder) page goes one level deeper. Every Node tool answers `--help` or `-h` by printing its usage to standard output and exiting 0, without doing any of its work. A command line a tool cannot use is refused the same way by every Node tool: an unknown flag, a flag without its value or with an empty one, and an unexpected argument are reported on standard error and exit **2**. So is a crash. So is a value a tool cannot use, before it does any work: a number that is not one or is out of range (a fraction where a whole number is needed), a regular expression that does not compile, a URL that is not an absolute `http` or `https` one, a date that is not ISO 8601, a value outside a fixed set, and options that exclude each other. A tool that reads its command line through `lib/cli.mjs` and takes search terms, file names or folder names takes one that starts with a dash after `--`.
+One-line-per-tool reference for every executable in the documentation repository: the eight Windows batch wrappers at the repository root, the Node and Python scripts under `scripts/` (cross-platform except for [`tbbuild.mjs`](#tbbuild), which drives the twinBASIC IDE), the `tbdocs` orchestrator and its CLI flags, and the PDF render driver. If you are looking for the day-to-day workflow rather than a cheat sheet, the [Building and Deployment](Building) page is the gentler read; if you are modifying the build pipeline itself, the [tbdocs Internals](Builder) page goes one level deeper. Every Node tool answers `--help` or `-h` by printing its usage to standard output and exiting 0, without doing any of its work. A command line a tool cannot use is refused the same way by every Node tool: an unknown flag, a flag without its value or with an empty one, and an unexpected argument are reported on standard error and exit **2**. So is a crash. So is a value a tool cannot use, before it does any work: a number that is not one or is out of range (a fraction where a whole number is needed), a regular expression that does not compile, a URL that is not an absolute `http` or `https` one, a date that is not ISO 8601, a value outside a fixed set, and options that exclude each other. A tool that reads its command line through `lib/cli.mjs` and takes search terms, file names or folder names takes one that starts with a dash after `--`.
 
 * TOC goes here
 {:toc}
 ## Batch wrappers at the repository root
 {: #batch-wrappers }
 
-All seven sit at the repository root, beside `package.json` --- not under `docs/`. Each uses `@pushd "%~dp0"` to run from that root regardless of where it is invoked from, and each entry below gives the POSIX equivalent of what it runs. Those equivalents have no `pushd` in front of them, so **run them from the repository root** --- `tbdocs`'s `--src docs`, [`check_publish_policy.mjs`](#check-publish-policy)'s default source root, and every path handed to [`render-book.mjs`](#bookrender-bookmjs) are all resolved against the working directory. `examples.bat` and `addin-test.bat` are the exceptions to "each entry below gives the POSIX equivalent": they need a twinBASIC install and drive the IDE, so they are Windows-only, and neither is part of the site build. Four other tools are Windows-specific for the same reason and are likewise not part of it: [`scripts/tbbuild.mjs`](#tbbuild) and [`scripts/tbrun.mjs`](#tbrun), which drive the twinBASIC IDE, and [`census_attributes.mjs`](#census-attributes) and [`build_package_api.mjs`](#build-package-api), which run the twinBASIC compiler's `export` verb --- though those two are cross-platform when given an already-exported tree with `--exported`. Nothing else in the repository is: `tbdocs` and every gate in both wrappers is a Node script, and CI runs all of them on `ubuntu-latest` except [`check_tree_fresh.mjs`](#check-tree-fresh), which guards against a failure mode CI cannot have.
+All eight sit at the repository root, beside `package.json` --- not under `docs/`. Each uses `@pushd "%~dp0"` to run from that root regardless of where it is invoked from, and each entry below gives the POSIX equivalent of what it runs. Those equivalents have no `pushd` in front of them, so **run them from the repository root** --- `tbdocs`'s `--src docs`, [`check_publish_policy.mjs`](#check-publish-policy)'s default source root, and every path handed to [`render-book.mjs`](#bookrender-bookmjs) are all resolved against the working directory. `examples.bat`, `addin-test.bat` and `ide-test.bat` are the exceptions to "each entry below gives the POSIX equivalent": they need a twinBASIC install and drive the IDE, so they are Windows-only, and neither is part of the site build. Four other tools are Windows-specific for the same reason and are likewise not part of it: [`scripts/tbbuild.mjs`](#tbbuild) and [`scripts/tbrun.mjs`](#tbrun), which drive the twinBASIC IDE, and [`census_attributes.mjs`](#census-attributes) and [`build_package_api.mjs`](#build-package-api), which run the twinBASIC compiler's `export` verb --- though those two are cross-platform when given an already-exported tree with `--exported`. Nothing else in the repository is: `tbdocs` and every gate in both wrappers is a Node script, and CI runs all of them on `ubuntu-latest` except [`check_tree_fresh.mjs`](#check-tree-fresh), which guards against a failure mode CI cannot have.
 
 ### build.bat
 
@@ -203,6 +203,21 @@ Tests twinBASIC IDE add-ins by machine: it builds each add-in under test, loads
 
 Exit codes: those of [`addin_test.mjs`](#addin-test), returned as they are: **0** every lane passed and the registry is as it was found, **1** a lane failed, **2** the harness failed, **3** the registry or a work folder was not put back.
 
+### ide-test.bat
+{: #ide-testbat }
+
+    ide-test.bat [flags]
+
+One invocation of [`ide_test.mjs`](#ide-test), with every flag passed straight through:
+
+    node scripts/ide_test.mjs [flags]
+
+Tests the twinBASIC IDE itself by machine: it opens a project in an IDE, operates the IDE the way a person would (the debugger, Export Project, the Packages dialog), and checks what the IDE did. It is the runner of [`addin-test.bat`](#addin-testbat) for scenarios that test the IDE rather than an add-in.
+
+**It is not one of the gates either**, and for the reasons `examples.bat` is not: it needs a twinBASIC install, and it needs Windows, a private desktop and a CDP-reachable WebView2. It is absent from `build.bat`, `check.bat`, `test.bat` and both CI workflows.
+
+Exit codes: those of [`ide_test.mjs`](#ide-test), returned as they are: **0** every lane passed and the registry is as it was found, **1** a lane failed, **2** the harness failed, **3** the registry or a work folder was not put back.
+
 ## CLI tools
 
 ### tbdocs --- node builder/tbdocs.mjs
@@ -1000,6 +1015,28 @@ fails if its IDE's add-in folder turns out to be anywhere else.
 
 Exit codes: **0** every lane passed, and the registry is as it was found; **1** a lane failed, or the run was interrupted; **2** the harness could not run: a refused command line, no IDE, no matching lane, a registry it could not record, or a crash after which the registry was put back; **3** the registry or a work folder was not put back (see the lines above), at the end of a run or after a crash, which wins over a 1 because the registry is what to repair.
 
+### ide_test.mjs
+{: #ide-test }
+
+    node scripts/ide_test.mjs [--only <regex>] [--port N] [--jobs N] [--timeout S]
+                              [--ide <path>] [--show|--hide]
+
+Runs the IDE scenarios under `test/ide/`: the scenarios that operate the IDE itself, such as
+the debugger, Export Project and the Packages dialog, rather than an add-in. It is the same
+runner as [`addin_test.mjs`](#addin-test), with the same flags, the same kind of lanes and the
+same exit codes: each file listed in `test/ide/lanes.mjs` is one **lane**, run by
+[`ide-test.bat`](#ide-testbat) in a process of its own, with its own DevTools port, work
+folder and private copy of the twinBASIC install. Run on its own, a scenario skips itself.
+The two differences are the suite and the default base port, which is 9660 here, so that a
+run of each tool never takes the other's ports. A run whose `test/ide/lanes.mjs` lists no lane
+matching `--only` is refused, as for `addin_test.mjs`.
+
+It leaves the registry as it found it, and checks, exactly as `addin_test.mjs` does. The rules
+of that tool apply here unchanged: every IDE it starts has a private `APPDATA` and
+`TB_ADDIN_TEST` set to `1`, and an IDE is ended by its process id and never by its image name.
+
+Exit codes: **0** every lane passed, and the registry is as it was found; **1** a lane failed, or the run was interrupted; **2** the harness could not run: a refused command line, no IDE, no matching lane, a registry it could not record, or a crash after which the registry was put back; **3** the registry or a work folder was not put back (see the lines above), at the end of a run or after a crash, which wins over a 1 because the registry is what to repair.
+
 ### check_tb_registry.mjs
 {: #check-tb-registry }
 
diff --git a/ide-test.bat b/ide-test.bat
new file mode 100644
index 00000000..56b7ff9c
--- /dev/null
+++ b/ide-test.bat
@@ -0,0 +1,31 @@
+@echo off
+@pushd "%~dp0"
+rem Test the twinBASIC IDE itself by machine: the scenarios under test\ide.
+rem
+rem Each lane in test\ide\lanes.mjs is a node:test file with its own copy of
+rem the twinBASIC install and its own DevTools port. It opens a project,
+rem operates the IDE the way a person does (the debugger, Export Project, the
+rem Packages dialog) and reads what the IDE did. The IDE's registry entries are
+rem put back as they were found at the end. addin-test.bat is the same runner
+rem for IDE add-ins; WIP.Harness.md says how both work.
+rem
+rem THIS IS NOT ONE OF THE GATES, for the reasons examples.bat is not: it
+rem needs a twinBASIC install and Windows, with a private desktop and a
+rem CDP-reachable WebView2, and neither is on the CI box. Keep it out of
+rem build.bat, check.bat, test.bat and both CI workflows.
+rem
+rem Arguments are passed straight through:
+rem
+rem   ide-test.bat --only export         just that lane
+rem   ide-test.bat --port 9700           lanes on ports 9700, 9701, ...
+rem   ide-test.bat --jobs 1              one lane at a time
+rem
+rem Exit: 0 every lane passed and the registry is as it was found, 1 a lane
+rem failed, 2 the harness could not run, 3 the registry or a work folder was
+rem not put back.
+node scripts/ide_test.mjs %*
+@rem popd resets ERRORLEVEL, so capture it first -- otherwise a failing lane
+@rem would report success to whatever called ide-test.bat.
+@set "IDE_TEST_ERR=%ERRORLEVEL%"
+@popd
+@exit /b %IDE_TEST_ERR%
diff --git a/scripts/addin_test.mjs b/scripts/addin_test.mjs
index 9c7f6416..c601e8c0 100644
--- a/scripts/addin_test.mjs
+++ b/scripts/addin_test.mjs
@@ -5,90 +5,30 @@
 //
 //     node scripts/addin_test.mjs [options]
 //
-//       --only <regex>    only the lanes whose name matches
-//       --port <n>        base DevTools port (default 9560); the lanes get n, n+1, ...
-//       --jobs <n>        lanes at once (default 2)
-//       --timeout <secs>  a lane still running after this long is ended (default 600)
-//       --ide <path>      the twinBASIC.exe to copy (default: $TB_IDE, else the
-//                         newest %USERPROFILE%/Desktop/twinBASIC_IDE_BETA_*)
-//       --show / --hide   as tbbuild's
+// The options, the exit codes and how a run works are in scripts/lib/lane-runner.mjs,
+// which ide_test.mjs shares; addin-test.bat is the wrapper. Not a gate.
 //
-// Exit: 0 every lane passed and the registry is as it was found, 1 a lane
-// failed or the run was interrupted, 2 the harness could not run (a refused
-// command line included) or crashed, 3 the registry or the work folders could
-// not be put back (the registry is what to repair, so 3 wins over 1).
+// What is specific to add-ins:
 //
-// Not a gate, for the reasons examples.bat is not one: it needs Windows and a
-// twinBASIC install. addin-test.bat is the wrapper.
-//
-// ---------------------------------------------------------------- how
-//
-// A lane is one scenario file. The file builds the add-ins it tests into its
-// lane's copy of the install and opens projects in it, one IDE at a time,
-// through scripts/lib/tb-lane.mjs; this script only hands each file its lane
-// (TB_ADDIN_LANE), runs the files a few at a time, and owns what they share:
-//
-//   * THE REGISTRY. One process owns it per run (lib/tb-registry.mjs). This
-//     one records it before the first lane starts, and the lanes inherit
-//     TB_REGISTRY_OWNER and leave it alone. Once every lane has ended it
-//     puts back the IDE's lists, the .twinproj association and the build
-//     targets the IDE remembers, then checks that nothing under the lanes'
-//     folders is left.
 //   * THE ADD-INS' OWN SETTINGS. An add-in's SaveSetting writes under
 //     HKCU\Software\VB and VBA Program Settings\<app>, the same key as any
 //     installed copy of that add-in. A lane names the applications its
-//     add-ins save settings for (`settings` in lanes.mjs); their keys are
-//     recorded before the first lane starts, deleted before each lane that
-//     names them, so that its add-ins start from their defaults, and put back
-//     at the end. Lanes that name the same application never run at once.
-//
-// Not %APPDATA%\twinBASIC\addins. The compiler loads the add-ins there too
-// (P6 in WIP.HelpAddin.md), but the IDE makes that folder's path from its own
-// environment, and every IDE a lane starts has an APPDATA inside the lane's
-// work folder (lib/tb-lane.mjs). So an add-in the user keeps there loads into
-// none of them, and the run has no need to refuse while one is there.
-//
-// Ctrl+C ends the lanes and still puts the registry back.
-
-import { spawn } from "node:child_process";
-import { existsSync, mkdirSync } from "node:fs";
-import { tmpdir } from "node:os";
-import path from "node:path";
-import { pathToFileURL } from "node:url";
-import {
-  die,
-  exitOnCrash,
-  numberOption,
-  parseCli,
-  printHelpAndExit,
-  refuseTogether,
-  regexOption,
-  withUsageError,
-} from "../lib/cli.mjs";
-import { removeTree } from "./lib/tb-ide-copy.mjs";
-import { wantShow } from "./lib/tb-ide.mjs";
-import { buildNumber, findIde } from "./lib/tb-install.mjs";
-import { LANE_ENV } from "./lib/tb-lane.mjs";
-import {
-  alive,
-  deleteSettings,
-  finishTidy,
-  ideLists,
-  norm,
-  restoreKeys,
-  SETTINGS_ROOT,
-  settingsKey,
-  snapshotKeys,
-  startTidy,
-  subkeyNames,
-  sweepArchitectureMemory,
-} from "./lib/tb-registry.mjs";
+//     add-ins save settings for (`settings` in lanes.mjs); the runner puts
+//     them back as found.
+//   * Not %APPDATA%\twinBASIC\addins. The compiler loads the add-ins there too
+//     (P6 in WIP.HelpAddin.md), but the IDE makes that folder's path from its
+//     own environment, and every IDE a lane starts has an APPDATA inside the
+//     lane's work folder (lib/tb-lane.mjs). So an add-in the user keeps there
+//     loads into none of them, and the run has no need to refuse while one is
+//     there.
+
+import { exitOnCrash } from "../lib/cli.mjs";
 import { REPO_ROOT } from "../lib/repo-paths.mjs";
+import { runLanes } from "./lib/lane-runner.mjs";
+import path from "node:path";
 
 exitOnCrash();
 
-const SUITE = path.join(REPO_ROOT, "test", "addin");
-
 const USAGE = `usage: node scripts/addin_test.mjs [--only REGEX] [--port N] [--jobs N] [--timeout S] [--ide <twinBASIC.exe>] [--show|--hide] [-h, --help]
 
 Runs the IDE add-in scenarios: every lane in test/addin/lanes.mjs, each in a
@@ -111,307 +51,11 @@ Exit codes:
   3  the registry or a work folder was not put back, at the end of a run or after a
      crash; see the lines above`;
 
-const { values } = withUsageError(() =>
-  parseCli(process.argv.slice(2), {
-    options: {
-      only: { type: "string" },
-      port: { type: "string" },
-      jobs: { type: "string" },
-      timeout: { type: "string" },
-      ide: { type: "string" },
-      show: { type: "boolean", default: false },
-      hide: { type: "boolean", default: false },
-      help: { type: "boolean", short: "h", default: false },
-    },
-    stopAt: ["help"],
-  }),
-);
-if (values.help) printHelpAndExit(USAGE);
-// setTimeout takes at most 2147483647 ms, so a lane's timeout is at most 2147483 s.
-const { only, basePort, jobs, laneTimeout } = withUsageError(() => {
-  refuseTogether(values, ["show", "hide"]);
-  return {
-    only: values.only ? regexOption(values.only, { option: "--only" }) : null,
-    basePort: numberOption(values.port ?? "9560", { option: "--port", integer: true, min: 1, max: 65535 }),
-    jobs: numberOption(values.jobs ?? "2", { option: "--jobs", integer: true, min: 1 }),
-    laneTimeout: numberOption(values.timeout ?? "600", { option: "--timeout", above: 0, max: 2147483 }) * 1000,
-  };
-});
-const show = wantShow({ show: values.show, hide: values.hide });
-
-// ---------------------------------------------------------------- refusals
-
-const ide = findIde(values.ide || undefined);
-if (!ide || !existsSync(ide)) {
-  die(
-    2,
-    "no twinBASIC IDE found: pass --ide <twinBASIC.exe>, set TB_IDE, " +
-      "or unpack a twinBASIC_IDE_BETA_<n> folder on your Desktop",
-  );
-}
-
-const manifest = (await import(pathToFileURL(path.join(SUITE, "lanes.mjs")).href)).default;
-const lanes = manifest
-  .map((l) => ({ ...l, name: l.name ?? path.basename(l.file).replace(/\.test\.mjs$/, "") }))
-  .filter((l) => !only || only.test(l.name))
-  .map((l, i) => ({
-    ...l,
-    settings: l.settings ?? [],
-    port: basePort + i,
-    work: path.join(tmpdir(), "tbaddin", String(basePort + i)),
-  }));
-if (!lanes.length) die(2, `no lane in ${path.join(SUITE, "lanes.mjs")} matches ${only}`);
-for (const l of lanes) {
-  if (!existsSync(path.join(SUITE, l.file))) die(2, `lane ${l.name}: no file ${path.join(SUITE, l.file)}`);
-  try {
-    l.settings.forEach(settingsKey);
-  } catch (e) {
-    die(2, `lane ${l.name}: ${e.message}`);
-  }
-}
-
-// ---------------------------------------------------------------- the registry
-
-// startTidy leaves the registry to a live owner that is not this process, and
-// such an owner would tidy only its own folders, not the lanes'.
-const owner = Number(process.env.TB_REGISTRY_OWNER);
-if (owner && owner !== process.pid && alive(owner)) {
-  die(
-    2,
-    `process ${owner} already owns the registry for a run (TB_REGISTRY_OWNER); ` + "run the add-in tests on their own",
-  );
-}
-for (const l of lanes) {
-  try {
-    removeTree(l.work);
-  } catch (e) {
-    die(2, `${l.work} could not be emptied (${e.code}): is a process from an earlier run still running?`);
-  }
-  mkdirSync(l.work, { recursive: true });
-}
-const tidy = startTidy({ prefixes: lanes.map((l) => l.work) });
-if (!tidy) die(2, "could not record the registry, so the run could not put it back");
-const apps = [...new Set(lanes.flatMap((l) => l.settings))];
-const snapshotSettings = () => (apps.length ? [].concat(snapshotKeys(apps.map(settingsKey))) : []);
-let settingsBefore, appsBefore;
-try {
-  settingsBefore = snapshotSettings();
-  // Only the names, to notice an application key the run creates that no lane
-  // named: an add-in saving settings nobody told the runner about.
-  appsBefore = subkeyNames(SETTINGS_ROOT).map((n) => n.toLowerCase());
-} catch (e) {
-  const tidied = finishTidy(tidy);
-  die(tidied ? 2 : 3, `could not record the add-ins' settings: ${e.message}`);
-}
-
-let interrupted = false;
-const children = new Set();
-
-// A crash from here on still puts back what the run recorded, as the end of a
-// run does: the lanes are ended first, as Ctrl+C ends them, so that no IDE
-// writes to the registry after it is put back. It exits 3 if the registry or a
-// work folder was not put back, and 2 if it was. A crash while putting it back
-// leaves the registry as it happens to be, so it exits 3 at once.
-let crashed = false,
-  putBackStarted = false,
-  putBackResult = null;
-process.removeAllListeners("uncaughtException");
-process.on("uncaughtException", (err) => {
-  console.error(err);
-  if (putBackResult) process.exit(putBackResult.problems.length ? 3 : 2);
-  if (crashed || putBackStarted) process.exit(3);
-  crashed = true;
-  for (const child of children) child.kill();
-  const deadline = Date.now() + 10_000;
-  const wait = setInterval(() => {
-    if (children.size && Date.now() < deadline) return;
-    clearInterval(wait);
-    const { tidied, problems } = putBack();
-    console.error(registryLine(tidied, problems));
-    process.exit(problems.length ? 3 : 2);
-  }, 100);
-});
-
-// ---------------------------------------------------------------- the lanes
-
-console.log(
-  `addin-test: BETA ${buildNumber(ide) ?? "?"}, ${lanes.length} lane(s) on ports ` +
-    `${basePort}-${basePort + lanes.length - 1}, ${Math.min(jobs, lanes.length)} at a time`,
-);
-
-process.on("SIGINT", () => {
-  if (interrupted) return;
-  interrupted = true;
-  console.error("\ninterrupted: ending the lanes, then putting the registry back");
-  for (const child of children) child.kill();
+await runLanes({
+  tool: "addin-test",
+  suite: path.join(REPO_ROOT, "test", "addin"),
+  workDir: "tbaddin",
+  defaultPort: 9560,
+  usage: USAGE,
+  subject: "add-in",
 });
-
-// A lane's output is held until it ends and then printed whole, so that two
-// lanes' reports never interleave.
-function runLane(l) {
-  return new Promise((resolve) => {
-    const t0 = Date.now();
-    let finished = false;
-    const finish = (r) => {
-      if (finished) return;
-      finished = true;
-      const secs = ((Date.now() - t0) / 1000).toFixed(1);
-      const verdict = r.code === 0 ? "passed" : r.timedOut ? "TIMED OUT" : "FAILED";
-      // node:test reports a test once it ends, so a lane ended in the middle
-      // of one, as a timeout or Ctrl+C ends it, has usually printed nothing.
-      const report = r.out.trimEnd() || "(the lane printed nothing before it ended)";
-      process.stdout.write(`\n--- ${l.name} (port ${l.port}): ${verdict} in ${secs} s\n${report}\n`);
-      resolve({ ...r, lane: l });
-    };
-    try {
-      if (l.settings.length) deleteSettings(l.settings);
-    } catch (e) {
-      finish({ code: null, out: `could not clear the settings of ${l.settings.join(", ")}: ${e.message}` });
-      return;
-    }
-    console.log(`  ${l.name}: started on port ${l.port}`);
-    const child = spawn(process.execPath, ["--test", "--test-reporter=spec", path.join(SUITE, l.file)], {
-      cwd: REPO_ROOT,
-      stdio: ["ignore", "pipe", "pipe"],
-      windowsHide: true,
-      env: { ...process.env, [LANE_ENV]: JSON.stringify({ name: l.name, port: l.port, work: l.work, ide, show }) },
-    });
-    children.add(child);
-    let out = "",
-      timedOut = false;
-    child.stdout.on("data", (d) => {
-      out += d;
-    });
-    child.stderr.on("data", (d) => {
-      out += d;
-    });
-    const timer = setTimeout(() => {
-      timedOut = true;
-      child.kill();
-    }, laneTimeout);
-    child.on("error", (e) => {
-      clearTimeout(timer);
-      children.delete(child);
-      finish({ code: null, out: `${out}\ncould not start the lane: ${e.message}`, timedOut });
-    });
-    child.on("close", (code) => {
-      clearTimeout(timer);
-      children.delete(child);
-      finish({ code, out, timedOut });
-    });
-  });
-}
-
-// A few lanes at a time, and never two that name the same application's
-// settings: each deletes the key before it starts, and its add-ins read it.
-async function runAll() {
-  const results = [];
-  const pending = [...lanes];
-  const running = new Map();
-  const clash = (a, b) => a.settings.some((s) => b.settings.includes(s));
-  while ((pending.length && !interrupted) || running.size) {
-    for (let i = 0; i < pending.length && running.size < jobs && !interrupted; ) {
-      const l = pending[i];
-      if ([...running.keys()].some((r) => clash(l, r))) {
-        i++;
-        continue;
-      }
-      pending.splice(i, 1);
-      running.set(
-        l,
-        runLane(l).then((r) => {
-          results.push(r);
-          running.delete(l);
-        }),
-      );
-    }
-    if (running.size) await Promise.race(running.values());
-  }
-  return results;
-}
-
-const results = await runAll();
-// A crash ended the lanes, so runAll returned; the crash handler puts the
-// registry back and exits, and its timer keeps the process alive until then.
-if (crashed) await new Promise(() => {});
-
-// ---------------------------------------------------------------- putting it back
-
-// Called once every lane has ended, at the end of a run or after a crash.
-function putBack() {
-  putBackStarted = true;
-  const problems = [];
-  const tidied = finishTidy(tidy);
-  if (!tidied) problems.push("the IDE's registry entries could not be put back (see the warning above)");
-  try {
-    if (apps.length) restoreKeys(settingsBefore);
-  } catch (e) {
-    problems.push(`the add-ins' settings could not be put back: ${e.message}`);
-  }
-
-  // The check that the run left nothing: an entry naming a lane's folder in the
-  // IDE's lists, a build target remembered for one, or an add-in's settings that
-  // differ from what was recorded. Another session's IDE that is open meanwhile
-  // can write its own copy of the recent list back, which is the one way an
-  // entry could return (WIP.Harness.md).
-  const folders = lanes.map((l) => norm(l.work) + "\\");
-  try {
-    const lists = ideLists();
-    const left = [...lists.projectState, ...lists.recentlyOpened].filter(
-      (p) => p && folders.some((f) => norm(p).startsWith(f)),
-    );
-    if (left.length) problems.push(`the IDE's lists still name the lanes' folders: ${left.join(", ")}`);
-    const targets = sweepArchitectureMemory(lanes.map((l) => l.work));
-    if (targets) problems.push(`${targets} build target(s) were still remembered for the lanes' folders`);
-    const settingsAfter = snapshotSettings();
-    for (let i = 0; i < apps.length; i++) {
-      if (JSON.stringify(settingsAfter[i]) !== JSON.stringify(settingsBefore[i])) {
-        problems.push(`the settings of ${apps[i]} are not as they were found`);
-      }
-    }
-    const named = apps.map((a) => a.toLowerCase());
-    const created = subkeyNames(SETTINGS_ROOT).filter(
-      (n) => !appsBefore.includes(n.toLowerCase()) && !named.includes(n.toLowerCase()),
-    );
-    if (created.length) {
-      problems.push(
-        `HKCU\\${SETTINGS_ROOT} gained ${created.map((n) => `"${n}"`).join(", ")} during the ` +
-          "run, which no lane names in test/addin/lanes.mjs. An add-in under test that saves settings " +
-          "must be named there, or its settings stay behind; the key is left as it is",
-      );
-    }
-  } catch (e) {
-    problems.push(`could not check the registry: ${e.message}`);
-  }
-
-  // A folder that will not delete is held open by a process that outlived its
-  // lane, which is worth hearing about (WIP.Harness.md, The IDE runs inside a job).
-  for (const l of lanes) {
-    try {
-      removeTree(l.work);
-    } catch (e) {
-      problems.push(`${l.work} could not be deleted (${e.code}): is a process of its lane still running?`);
-    }
-  }
-  putBackResult = { tidied, problems };
-  return putBackResult;
-}
-
-function registryLine(tidied, problems) {
-  const settingsNote = apps.length ? `, and the settings of ${apps.join(", ")} as found` : "";
-  return problems.length
-    ? `registry and work folders: ${problems.length} problem(s)\n  ${problems.join("\n  ")}`
-    : `registry: put back (${tidied.projectState} project-state, ${tidied.recentlyOpened} recent-list ` +
-        `and ${tidied.association ?? "no"} association writes); nothing names the lanes' folders${settingsNote}`;
-}
-
-const { tidied, problems } = putBack();
-const failed = results.filter((r) => r.code !== 0);
-console.log("");
-console.log(registryLine(tidied, problems));
-console.log(
-  `${results.length} of ${lanes.length} lane(s) ran: ${results.length - failed.length} passed` +
-    (failed.length ? `, ${failed.length} failed (${failed.map((r) => r.lane.name).join(", ")})` : "") +
-    (interrupted ? "; interrupted" : ""),
-);
-process.exit(problems.length ? 3 : failed.length || interrupted ? 1 : 0);
diff --git a/scripts/check_cli.mjs b/scripts/check_cli.mjs
index 9f31c903..66ec1fc1 100644
--- a/scripts/check_cli.mjs
+++ b/scripts/check_cli.mjs
@@ -812,6 +812,10 @@ const CASES = [
   { tool: "scripts/addin_test.mjs", args: ["--ide"], exit: 2, stderr: "--ide needs a value\n" },
   { tool: "scripts/addin_test.mjs", args: ["--ide", ""], exit: 2, stderr: "--ide needs a non-empty value\n" },
   { tool: "scripts/addin_test.mjs", args: ["--ide", "no-such.exe"], exit: 2, stderr: /^no twinBASIC IDE found: pass --ide / },
+  { tool: "scripts/ide_test.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/ide_test\.mjs / },
+  { tool: "scripts/ide_test.mjs", args: ["--ide"], exit: 2, stderr: "--ide needs a value\n" },
+  { tool: "scripts/ide_test.mjs", args: ["--ide", ""], exit: 2, stderr: "--ide needs a non-empty value\n" },
+  { tool: "scripts/ide_test.mjs", args: ["--ide", "no-such.exe"], exit: 2, stderr: /^no twinBASIC IDE found: pass --ide / },
   { tool: "scripts/check_examples.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/check_examples\.mjs \[options\]\n/ },
   { tool: "scripts/check_examples.mjs", args: ["--jobs", "0"], exit: 2, stderr: "check_examples: --jobs expects a whole number of at least 1, got: 0\n" },
   { tool: "scripts/check_examples.mjs", args: ["--batch", "1.5"], exit: 2, stderr: "check_examples: --batch expects a whole number of at least 1, got: 1.5\n" },
@@ -1023,6 +1027,7 @@ const HELP_TOOLS = {
   "eval/site_search.mjs": "Usage: node eval/site_search.mjs ",
   "eval/transcript.mjs": "Usage: node eval/transcript.mjs ",
   "scripts/addin_test.mjs": null,
+  "scripts/ide_test.mjs": null,
   "scripts/build_dot_metrics.mjs": null,
   "scripts/build_package_api.mjs": null,
   "scripts/census_attributes.mjs": null,
@@ -1100,6 +1105,7 @@ const REFUSALS = {
   "eval/site_search.mjs": ["site"],
   "eval/transcript.mjs": [null],
   "scripts/addin_test.mjs": ["ide"],
+  "scripts/ide_test.mjs": ["ide"],
   "scripts/build_dot_metrics.mjs": [null],
   "scripts/build_package_api.mjs": ["out"],
   "scripts/census_attributes.mjs": ["out"],
@@ -1254,6 +1260,23 @@ bad(
 );
 bad("scripts/addin_test.mjs", ["--show", "--hide"], "--show and --hide cannot be given together\n");
 
+bad("scripts/ide_test.mjs", ["--only", "("], REGEX_REASON("--only", "("));
+bad("scripts/ide_test.mjs", ["--port", "0"], NOT_PORT(0) + "\n");
+bad("scripts/ide_test.mjs", ["--port=1.5"], NOT_PORT(1.5) + "\n");
+bad("scripts/ide_test.mjs", ["--jobs", "0"], NOT_COUNT("--jobs", 0) + "\n");
+bad("scripts/ide_test.mjs", ["--jobs=1.5"], NOT_COUNT("--jobs", 1.5) + "\n");
+bad(
+  "scripts/ide_test.mjs",
+  ["--timeout", "0"],
+  "--timeout expects a number greater than 0 and at most 2147483, got: 0\n",
+);
+bad(
+  "scripts/ide_test.mjs",
+  ["--timeout", "2147484"],
+  "--timeout expects a number greater than 0 and at most 2147483, got: 2147484\n",
+);
+bad("scripts/ide_test.mjs", ["--show", "--hide"], "--show and --hide cannot be given together\n");
+
 // check_examples prints "check_examples: " before the message.
 {
   const tool = "scripts/check_examples.mjs";
diff --git a/scripts/ide_test.mjs b/scripts/ide_test.mjs
new file mode 100644
index 00000000..70b45637
--- /dev/null
+++ b/scripts/ide_test.mjs
@@ -0,0 +1,49 @@
+#!/usr/bin/env node
+// Run the IDE scenarios: every lane listed in test/ide/lanes.mjs, each a
+// node:test file run in a process of its own, with its own DevTools port, work
+// folder and copy of the twinBASIC install. These operate the IDE itself (the
+// debugger, Export Project, the Packages dialog); add-ins are addin_test.mjs's.
+//
+//     node scripts/ide_test.mjs [options]
+//
+// The options, the exit codes and how a run works are in scripts/lib/lane-runner.mjs,
+// which addin_test.mjs shares; ide-test.bat is the wrapper. Not a gate. The base
+// port differs from addin_test.mjs's (9660 against 9560) so the two never collide.
+
+import path from "node:path";
+import { exitOnCrash } from "../lib/cli.mjs";
+import { REPO_ROOT } from "../lib/repo-paths.mjs";
+import { runLanes } from "./lib/lane-runner.mjs";
+
+exitOnCrash();
+
+const USAGE = `usage: node scripts/ide_test.mjs [--only REGEX] [--port N] [--jobs N] [--timeout S] [--ide <twinBASIC.exe>] [--show|--hide] [-h, --help]
+
+Runs the IDE scenarios: every lane in test/ide/lanes.mjs, each in a process of
+its own with its own IDE copy, DevTools port and work folder.
+
+  --only <regex>    only the lanes whose name matches
+  --port <n>        base DevTools port (default 9660); the lanes get n, n+1, ...
+  --jobs <n>        lanes at once (default 2)
+  --timeout <secs>  a lane still running after this long is ended (default 600)
+  --ide <path>      the twinBASIC.exe to copy (default: $TB_IDE, else the
+                    newest twinBASIC_IDE_BETA_* on the Desktop)
+  --show, --hide    as tbbuild's
+  -h, --help        print this text and exit
+
+Exit codes:
+  0  every lane passed, and the registry is as it was found
+  1  a lane failed, or the run was interrupted
+  2  the harness could not run: a refused command line, no IDE, no matching lane, a
+     registry it could not record, or a crash after which the registry was put back
+  3  the registry or a work folder was not put back, at the end of a run or after a
+     crash; see the lines above`;
+
+await runLanes({
+  tool: "ide-test",
+  suite: path.join(REPO_ROOT, "test", "ide"),
+  workDir: "tbide",
+  defaultPort: 9660,
+  usage: USAGE,
+  subject: "IDE",
+});
diff --git a/scripts/lib/lane-runner.mjs b/scripts/lib/lane-runner.mjs
new file mode 100644
index 00000000..8bc060ba
--- /dev/null
+++ b/scripts/lib/lane-runner.mjs
@@ -0,0 +1,417 @@
+// The lane runner behind scripts/addin_test.mjs (addin-test.bat) and
+// scripts/ide_test.mjs (ide-test.bat): every lane listed in a suite's lanes.mjs,
+// each a node:test file run in a process of its own, with its own DevTools port,
+// work folder and copy of the twinBASIC install.
+//
+// The two tools differ only in what they are given: the suite folder, their
+// name, the work folder under the temp directory, the default base port, and
+// the usage text. Everything else, the options included, is here, so the two
+// cannot drift apart. The entry scripts call exitOnCrash() before calling
+// runLanes().
+//
+// Options, as each tool's usage text states them:
+//
+//       --only <regex>    only the lanes whose name matches
+//       --port <n>        base DevTools port; the lanes get n, n+1, ...
+//       --jobs <n>        lanes at once (default 2)
+//       --timeout <secs>  a lane still running after this long is ended (default 600)
+//       --ide <path>      the twinBASIC.exe to copy (default: $TB_IDE, else the
+//                         newest %USERPROFILE%/Desktop/twinBASIC_IDE_BETA_*)
+//       --show / --hide   as tbbuild's
+//
+// Exit: 0 every lane passed and the registry is as it was found, 1 a lane
+// failed or the run was interrupted, 2 the harness could not run (a refused
+// command line included) or crashed, 3 the registry or the work folders could
+// not be put back (the registry is what to repair, so 3 wins over 1).
+//
+// Not a gate, for the reasons examples.bat is not one: it needs Windows and a
+// twinBASIC install.
+//
+// ---------------------------------------------------------------- how
+//
+// A lane is one scenario file. The file operates the IDE in its lane's copy of
+// the install, one IDE at a time, through scripts/lib/tb-lane.mjs; this module
+// only hands each file its lane (LANE_ENV), runs the files a few at a time, and
+// owns what they share:
+//
+//   * THE REGISTRY. One process owns it per run (lib/tb-registry.mjs). This
+//     one records it before the first lane starts, and the lanes inherit
+//     TB_REGISTRY_OWNER and leave it alone. Once every lane has ended it
+//     puts back the IDE's lists, the .twinproj association and the build
+//     targets the IDE remembers, then checks that nothing under the lanes'
+//     folders is left.
+//   * THE LANES' SETTINGS. SaveSetting writes under HKCU\Software\VB and VBA
+//     Program Settings\<app>, the same key as any installed copy of the
+//     program that saves it. A lane names the applications its program saves
+//     settings for (`settings` in lanes.mjs); their keys are recorded before
+//     the first lane starts, deleted before each lane that names them, so that
+//     its program starts from its defaults, and put back at the end. Lanes
+//     that name the same application never run at once.
+//
+// Ctrl+C ends the lanes and still puts the registry back.
+//
+// What only the add-in tool has to say about its lanes (the add-ins' own
+// settings, %APPDATA%\twinBASIC\addins) is with its lanes, in
+// test/addin/lanes.mjs and scripts/lib/tb-lane.mjs: every IDE a lane starts has
+// an APPDATA inside the lane's work folder, so an add-in the user keeps in the
+// real one (P6 in WIP.HelpAddin.md) loads into none of them, and the run has no
+// need to refuse while one is there.
+
+import { spawn } from "node:child_process";
+import { existsSync, mkdirSync } from "node:fs";
+import { tmpdir } from "node:os";
+import path from "node:path";
+import { pathToFileURL } from "node:url";
+import {
+  die,
+  numberOption,
+  parseCli,
+  printHelpAndExit,
+  refuseTogether,
+  regexOption,
+  withUsageError,
+} from "../../lib/cli.mjs";
+import { REPO_ROOT } from "../../lib/repo-paths.mjs";
+import { removeTree } from "./tb-ide-copy.mjs";
+import { wantShow } from "./tb-ide.mjs";
+import { buildNumber, findIde } from "./tb-install.mjs";
+import { LANE_ENV } from "./tb-lane.mjs";
+import {
+  alive,
+  deleteSettings,
+  finishTidy,
+  ideLists,
+  norm,
+  restoreKeys,
+  SETTINGS_ROOT,
+  settingsKey,
+  snapshotKeys,
+  startTidy,
+  subkeyNames,
+  sweepArchitectureMemory,
+} from "./tb-registry.mjs";
+
+/**
+ * Parse the command line, run the suite's lanes and exit with the run's code.
+ * Never returns.
+ *
+ * @param {object} o
+ * @param {string} o.tool     the tool's name in messages ("addin-test")
+ * @param {string} o.suite    the suite folder, holding lanes.mjs and the scenario files
+ * @param {string} o.workDir  the folder under the temp directory the lanes' work folders go in
+ * @param {number} o.defaultPort  the base DevTools port when --port is not given
+ * @param {string} o.usage    the tool's whole usage text, printed by --help and on a refused command line
+ * @param {string} o.subject  what a lane's scenario operates, as a noun in messages ("add-in")
+ */
+export async function runLanes({ tool, suite: SUITE, workDir, defaultPort, usage: USAGE, subject }) {
+  const { values } = withUsageError(() =>
+    parseCli(process.argv.slice(2), {
+      options: {
+        only: { type: "string" },
+        port: { type: "string" },
+        jobs: { type: "string" },
+        timeout: { type: "string" },
+        ide: { type: "string" },
+        show: { type: "boolean", default: false },
+        hide: { type: "boolean", default: false },
+        help: { type: "boolean", short: "h", default: false },
+      },
+      stopAt: ["help"],
+    }),
+  );
+  if (values.help) printHelpAndExit(USAGE);
+  // setTimeout takes at most 2147483647 ms, so a lane's timeout is at most 2147483 s.
+  const { only, basePort, jobs, laneTimeout } = withUsageError(() => {
+    refuseTogether(values, ["show", "hide"]);
+    return {
+      only: values.only ? regexOption(values.only, { option: "--only" }) : null,
+      basePort: numberOption(values.port ?? String(defaultPort), {
+        option: "--port",
+        integer: true,
+        min: 1,
+        max: 65535,
+      }),
+      jobs: numberOption(values.jobs ?? "2", { option: "--jobs", integer: true, min: 1 }),
+      laneTimeout: numberOption(values.timeout ?? "600", { option: "--timeout", above: 0, max: 2147483 }) * 1000,
+    };
+  });
+  const show = wantShow({ show: values.show, hide: values.hide });
+
+  // ---------------------------------------------------------------- refusals
+
+  const ide = findIde(values.ide || undefined);
+  if (!ide || !existsSync(ide)) {
+    die(
+      2,
+      "no twinBASIC IDE found: pass --ide <twinBASIC.exe>, set TB_IDE, " +
+        "or unpack a twinBASIC_IDE_BETA_<n> folder on your Desktop",
+    );
+  }
+
+  const manifest = (await import(pathToFileURL(path.join(SUITE, "lanes.mjs")).href)).default;
+  const lanes = manifest
+    .map((l) => ({ ...l, name: l.name ?? path.basename(l.file).replace(/\.test\.mjs$/, "") }))
+    .filter((l) => !only || only.test(l.name))
+    .map((l, i) => ({
+      ...l,
+      settings: l.settings ?? [],
+      port: basePort + i,
+      work: path.join(tmpdir(), workDir, String(basePort + i)),
+    }));
+  if (!lanes.length) die(2, `no lane in ${path.join(SUITE, "lanes.mjs")} matches ${only}`);
+  for (const l of lanes) {
+    if (!existsSync(path.join(SUITE, l.file))) die(2, `lane ${l.name}: no file ${path.join(SUITE, l.file)}`);
+    try {
+      l.settings.forEach(settingsKey);
+    } catch (e) {
+      die(2, `lane ${l.name}: ${e.message}`);
+    }
+  }
+
+  // ---------------------------------------------------------------- the registry
+
+  // startTidy leaves the registry to a live owner that is not this process, and
+  // such an owner would tidy only its own folders, not the lanes'.
+  const owner = Number(process.env.TB_REGISTRY_OWNER);
+  if (owner && owner !== process.pid && alive(owner)) {
+    die(
+      2,
+      `process ${owner} already owns the registry for a run (TB_REGISTRY_OWNER); ` +
+        `run the ${subject} tests on their own`,
+    );
+  }
+  for (const l of lanes) {
+    try {
+      removeTree(l.work);
+    } catch (e) {
+      die(2, `${l.work} could not be emptied (${e.code}): is a process from an earlier run still running?`);
+    }
+    mkdirSync(l.work, { recursive: true });
+  }
+  const tidy = startTidy({ prefixes: lanes.map((l) => l.work) });
+  if (!tidy) die(2, "could not record the registry, so the run could not put it back");
+  const apps = [...new Set(lanes.flatMap((l) => l.settings))];
+  const snapshotSettings = () => (apps.length ? [].concat(snapshotKeys(apps.map(settingsKey))) : []);
+  let settingsBefore, appsBefore;
+  try {
+    settingsBefore = snapshotSettings();
+    // Only the names, to notice an application key the run creates that no lane
+    // named: a program saving settings nobody told the runner about.
+    appsBefore = subkeyNames(SETTINGS_ROOT).map((n) => n.toLowerCase());
+  } catch (e) {
+    const tidied = finishTidy(tidy);
+    die(tidied ? 2 : 3, `could not record the ${subject}s' settings: ${e.message}`);
+  }
+
+  let interrupted = false;
+  const children = new Set();
+
+  // A crash from here on still puts back what the run recorded, as the end of a
+  // run does: the lanes are ended first, as Ctrl+C ends them, so that no IDE
+  // writes to the registry after it is put back. It exits 3 if the registry or a
+  // work folder was not put back, and 2 if it was. A crash while putting it back
+  // leaves the registry as it happens to be, so it exits 3 at once.
+  let crashed = false,
+    putBackStarted = false,
+    putBackResult = null;
+  process.removeAllListeners("uncaughtException");
+  process.on("uncaughtException", (err) => {
+    console.error(err);
+    if (putBackResult) process.exit(putBackResult.problems.length ? 3 : 2);
+    if (crashed || putBackStarted) process.exit(3);
+    crashed = true;
+    for (const child of children) child.kill();
+    const deadline = Date.now() + 10_000;
+    const wait = setInterval(() => {
+      if (children.size && Date.now() < deadline) return;
+      clearInterval(wait);
+      const { tidied, problems } = putBack();
+      console.error(registryLine(tidied, problems));
+      process.exit(problems.length ? 3 : 2);
+    }, 100);
+  });
+
+  // ---------------------------------------------------------------- the lanes
+
+  console.log(
+    `${tool}: BETA ${buildNumber(ide) ?? "?"}, ${lanes.length} lane(s) on ports ` +
+      `${basePort}-${basePort + lanes.length - 1}, ${Math.min(jobs, lanes.length)} at a time`,
+  );
+
+  process.on("SIGINT", () => {
+    if (interrupted) return;
+    interrupted = true;
+    console.error("\ninterrupted: ending the lanes, then putting the registry back");
+    for (const child of children) child.kill();
+  });
+
+  // A lane's output is held until it ends and then printed whole, so that two
+  // lanes' reports never interleave.
+  function runLane(l) {
+    return new Promise((resolve) => {
+      const t0 = Date.now();
+      let finished = false;
+      const finish = (r) => {
+        if (finished) return;
+        finished = true;
+        const secs = ((Date.now() - t0) / 1000).toFixed(1);
+        const verdict = r.code === 0 ? "passed" : r.timedOut ? "TIMED OUT" : "FAILED";
+        // node:test reports a test once it ends, so a lane ended in the middle
+        // of one, as a timeout or Ctrl+C ends it, has usually printed nothing.
+        const report = r.out.trimEnd() || "(the lane printed nothing before it ended)";
+        process.stdout.write(`\n--- ${l.name} (port ${l.port}): ${verdict} in ${secs} s\n${report}\n`);
+        resolve({ ...r, lane: l });
+      };
+      try {
+        if (l.settings.length) deleteSettings(l.settings);
+      } catch (e) {
+        finish({ code: null, out: `could not clear the settings of ${l.settings.join(", ")}: ${e.message}` });
+        return;
+      }
+      console.log(`  ${l.name}: started on port ${l.port}`);
+      const child = spawn(process.execPath, ["--test", "--test-reporter=spec", path.join(SUITE, l.file)], {
+        cwd: REPO_ROOT,
+        stdio: ["ignore", "pipe", "pipe"],
+        windowsHide: true,
+        env: { ...process.env, [LANE_ENV]: JSON.stringify({ name: l.name, port: l.port, work: l.work, ide, show }) },
+      });
+      children.add(child);
+      let out = "",
+        timedOut = false;
+      child.stdout.on("data", (d) => {
+        out += d;
+      });
+      child.stderr.on("data", (d) => {
+        out += d;
+      });
+      const timer = setTimeout(() => {
+        timedOut = true;
+        child.kill();
+      }, laneTimeout);
+      child.on("error", (e) => {
+        clearTimeout(timer);
+        children.delete(child);
+        finish({ code: null, out: `${out}\ncould not start the lane: ${e.message}`, timedOut });
+      });
+      child.on("close", (code) => {
+        clearTimeout(timer);
+        children.delete(child);
+        finish({ code, out, timedOut });
+      });
+    });
+  }
+
+  // A few lanes at a time, and never two that name the same application's
+  // settings: each deletes the key before it starts, and its program reads it.
+  async function runAll() {
+    const results = [];
+    const pending = [...lanes];
+    const running = new Map();
+    const clash = (a, b) => a.settings.some((s) => b.settings.includes(s));
+    while ((pending.length && !interrupted) || running.size) {
+      for (let i = 0; i < pending.length && running.size < jobs && !interrupted; ) {
+        const l = pending[i];
+        if ([...running.keys()].some((r) => clash(l, r))) {
+          i++;
+          continue;
+        }
+        pending.splice(i, 1);
+        running.set(
+          l,
+          runLane(l).then((r) => {
+            results.push(r);
+            running.delete(l);
+          }),
+        );
+      }
+      if (running.size) await Promise.race(running.values());
+    }
+    return results;
+  }
+
+  const results = await runAll();
+  // A crash ended the lanes, so runAll returned; the crash handler puts the
+  // registry back and exits, and its timer keeps the process alive until then.
+  if (crashed) await new Promise(() => {});
+
+  // ---------------------------------------------------------------- putting it back
+
+  // Called once every lane has ended, at the end of a run or after a crash.
+  function putBack() {
+    putBackStarted = true;
+    const problems = [];
+    const tidied = finishTidy(tidy);
+    if (!tidied) problems.push("the IDE's registry entries could not be put back (see the warning above)");
+    try {
+      if (apps.length) restoreKeys(settingsBefore);
+    } catch (e) {
+      problems.push(`the ${subject}s' settings could not be put back: ${e.message}`);
+    }
+
+    // The check that the run left nothing: an entry naming a lane's folder in the
+    // IDE's lists, a build target remembered for one, or settings that differ
+    // from what was recorded. Another session's IDE that is open meanwhile
+    // can write its own copy of the recent list back, which is the one way an
+    // entry could return (WIP.Harness.md).
+    const folders = lanes.map((l) => norm(l.work) + "\\");
+    try {
+      const lists = ideLists();
+      const left = [...lists.projectState, ...lists.recentlyOpened].filter(
+        (p) => p && folders.some((f) => norm(p).startsWith(f)),
+      );
+      if (left.length) problems.push(`the IDE's lists still name the lanes' folders: ${left.join(", ")}`);
+      const targets = sweepArchitectureMemory(lanes.map((l) => l.work));
+      if (targets) problems.push(`${targets} build target(s) were still remembered for the lanes' folders`);
+      const settingsAfter = snapshotSettings();
+      for (let i = 0; i < apps.length; i++) {
+        if (JSON.stringify(settingsAfter[i]) !== JSON.stringify(settingsBefore[i])) {
+          problems.push(`the settings of ${apps[i]} are not as they were found`);
+        }
+      }
+      const named = apps.map((a) => a.toLowerCase());
+      const created = subkeyNames(SETTINGS_ROOT).filter(
+        (n) => !appsBefore.includes(n.toLowerCase()) && !named.includes(n.toLowerCase()),
+      );
+      if (created.length) {
+        problems.push(
+          `HKCU\\${SETTINGS_ROOT} gained ${created.map((n) => `"${n}"`).join(", ")} during the ` +
+            `run, which no lane names in test/${path.basename(SUITE)}/lanes.mjs. An ${subject} under test that saves settings ` +
+            "must be named there, or its settings stay behind; the key is left as it is",
+        );
+      }
+    } catch (e) {
+      problems.push(`could not check the registry: ${e.message}`);
+    }
+
+    // A folder that will not delete is held open by a process that outlived its
+    // lane, which is worth hearing about (WIP.Harness.md, The IDE runs inside a job).
+    for (const l of lanes) {
+      try {
+        removeTree(l.work);
+      } catch (e) {
+        problems.push(`${l.work} could not be deleted (${e.code}): is a process of its lane still running?`);
+      }
+    }
+    putBackResult = { tidied, problems };
+    return putBackResult;
+  }
+
+  function registryLine(tidied, problems) {
+    const settingsNote = apps.length ? `, and the settings of ${apps.join(", ")} as found` : "";
+    return problems.length
+      ? `registry and work folders: ${problems.length} problem(s)\n  ${problems.join("\n  ")}`
+      : `registry: put back (${tidied.projectState} project-state, ${tidied.recentlyOpened} recent-list ` +
+          `and ${tidied.association ?? "no"} association writes); nothing names the lanes' folders${settingsNote}`;
+  }
+
+  const { tidied, problems } = putBack();
+  const failed = results.filter((r) => r.code !== 0);
+  console.log("");
+  console.log(registryLine(tidied, problems));
+  console.log(
+    `${results.length} of ${lanes.length} lane(s) ran: ${results.length - failed.length} passed` +
+      (failed.length ? `, ${failed.length} failed (${failed.map((r) => r.lane.name).join(", ")})` : "") +
+      (interrupted ? "; interrupted" : ""),
+  );
+  process.exit(problems.length ? 3 : failed.length || interrupted ? 1 : 0);
+}
diff --git a/test/README.md b/test/README.md
index 1862ec29..9cbdff3e 100644
--- a/test/README.md
+++ b/test/README.md
@@ -11,6 +11,9 @@ is input for three tools:
   ([WIP.ExamplesBuild.md](../WIP.ExamplesBuild.md)).
 - `addin/` for [`scripts/addin_test.mjs`](../scripts/addin_test.mjs), which `addin-test.bat`
   runs: the IDE add-in scenarios ([test/addin](#testaddin), at the end).
+- `ide/` for [`scripts/ide_test.mjs`](../scripts/ide_test.mjs), which `ide-test.bat` runs:
+  the scenarios that operate the IDE itself. It is the add-in runner over its own
+  `lanes.mjs`, and its scenario files use `scenario` from `addin/scenario.mjs`.
 
 If a fixture case has just gone red, start at [The invariant, and how it
 breaks](#the-invariant-and-how-it-breaks) --- the commit that broke it need not have touched
diff --git a/test/addin/scenario.mjs b/test/addin/scenario.mjs
index 848588cc..3b54045e 100644
--- a/test/addin/scenario.mjs
+++ b/test/addin/scenario.mjs
@@ -11,7 +11,8 @@
 //       test("...", async () => { ...tb-operate.mjs calls on c... });
 //     });
 //
-// Outside addin-test.bat there is no lane, so the block is skipped and a bare
+// The scenario files under test/ide use it too. Outside addin-test.bat and
+// ide-test.bat there is no lane, so the block is skipped and a bare
 // `node --test` never starts an IDE.
 
 import { after, describe, test } from "node:test";
@@ -33,7 +34,7 @@ import { addinLane } from "../../scripts/lib/tb-lane.mjs";
  */
 export function scenario(title, fn) {
   const lane = addinLane();
-  describe(title, { skip: lane ? false : "run it with addin-test.bat" }, () => {
+  describe(title, { skip: lane ? false : "run it with addin-test.bat or ide-test.bat" }, () => {
     const cleanup = fn(lane);
     let closed = false;
     const close = async () => {
diff --git a/test/ide/export.test.mjs b/test/ide/export.test.mjs
new file mode 100644
index 00000000..3d56617a
--- /dev/null
+++ b/test/ide/export.test.mjs
@@ -0,0 +1,108 @@
+// File > Export Project, measured: what the IDE's own exportProjectTo() does to
+// the folder it exports into. It is what the menu command calls once the
+// Export Path is known, and it opens no folder picker. Every folder this file
+// exports into, and every folder a junction in one points to, is inside the
+// lane's work folder: one of the behaviours tested deletes through a junction.
+//
+// Each test states what BETA 983 and 995 do. If one fails after an IDE update,
+// the IDE has changed: update the matching entry in BUGS-TO-REPORT.md, and
+// then this file.
+//
+// Run it with ide-test.bat, which gives it a lane; on its own it is skipped.
+
+import assert from "node:assert/strict";
+import { chmodSync, existsSync, mkdirSync, readdirSync, symlinkSync, writeFileSync } from "node:fs";
+import path from "node:path";
+import { before, test } from "node:test";
+import { fileURLToPath } from "node:url";
+import { consoleMark, linesSince } from "../../scripts/lib/tb-ide-console.mjs";
+import { messageBoxes, waitFor } from "../../scripts/lib/tb-operate.mjs";
+import { scenario } from "../addin/scenario.mjs";
+
+const HERE = path.dirname(fileURLToPath(import.meta.url));
+const PROJECT = path.join(HERE, "probes", "export");
+
+// Every file under a folder, as paths relative to it.
+function filesUnder(dir) {
+  if (!existsSync(dir)) return [];
+  return readdirSync(dir, { recursive: true, withFileTypes: true })
+    .filter((e) => e.isFile())
+    .map((e) => path.relative(dir, path.join(e.parentPath, e.name)));
+}
+
+scenario("Export Project", (lane) => {
+  let c;
+  const root = path.join(lane.work, "export");
+  const readOnly = [];
+
+  // Export into a folder and wait for the compiler's last [EXPORT] line; the
+  // [EXPORT] lines, without the prefix and trimmed.
+  async function exportTo(folder) {
+    const mark = await consoleMark(c);
+    await c.evaluate(`exportProjectTo(${JSON.stringify(folder)}, true), null`);
+    const lines = await waitFor(
+      c,
+      async () => {
+        const l = (await linesSince(c, mark, { prefix: "[EXPORT]" })).map((s) => s.trim());
+        return l.some((s) => s.startsWith("COMPLETED") || s === "export failed.") ? l : null;
+      },
+      { timeout: 60 * 1000 },
+    );
+    assert.ok(lines, `no [EXPORT] COMPLETED or export failed. line for ${folder}`);
+    return lines;
+  }
+
+  before(async () => {
+    mkdirSync(root, { recursive: true });
+    c = await lane.open(PROJECT);
+  });
+
+  test("an export into an empty folder writes the compiler packages", async () => {
+    const out = path.join(root, "plain");
+    mkdirSync(out);
+    const lines = await exportTo(out);
+    const files = filesUnder(out);
+    const packages = [...new Set(files.filter((f) => f.startsWith("Packages\\")).map((f) => f.split("\\")[1]))];
+    assert.match(lines.at(-1), /^COMPLETED \(\d+ folders, \d+ files\)$/);
+    assert.ok(packages.includes("VBA"), `no Packages\\VBA among ${packages.join(", ")}`);
+  });
+
+  test("a junction in the export folder is followed, and its target emptied", async () => {
+    const out = path.join(root, "junction");
+    const outside = path.join(root, "outside");
+    mkdirSync(out);
+    mkdirSync(outside);
+    writeFileSync(path.join(outside, "precious.txt"), "keep me\n");
+    symlinkSync(outside, path.join(out, "linked"), "junction");
+    const lines = await exportTo(out);
+    assert.ok(
+      lines.some((l) => /^DELETED: .*\\linked\\precious\.txt$/.test(l)),
+      "the export no longer deletes through the junction",
+    );
+    assert.deepEqual(filesUnder(outside), []);
+  });
+
+  test("a read-only file stops the export part-way, and the IDE reports nothing", async () => {
+    const out = path.join(root, "readonly");
+    mkdirSync(out);
+    for (const name of ["a-first.txt", "m-readonly.txt", "z-last.txt"]) writeFileSync(path.join(out, name), "x\n");
+    const ro = path.join(out, "m-readonly.txt");
+    chmodSync(ro, 0o444);
+    readOnly.push(ro);
+    const lines = await exportTo(out);
+    const boxes = await messageBoxes(c);
+    assert.deepEqual(lines.slice(-3), [
+      `DELETE FAILED: \\\\?\\${ro}`,
+      "ERROR: unable to clean the output folder",
+      "export failed.",
+    ]);
+    assert.deepEqual(filesUnder(out).sort(), ["m-readonly.txt", "z-last.txt"]);
+    assert.deepEqual(boxes, []);
+  });
+
+  // The runner removes the work folder afterwards, and a read-only file would
+  // stop it.
+  return () => {
+    for (const f of readOnly) if (existsSync(f)) chmodSync(f, 0o666);
+  };
+});
diff --git a/test/ide/lanes.mjs b/test/ide/lanes.mjs
new file mode 100644
index 00000000..f8183173
--- /dev/null
+++ b/test/ide/lanes.mjs
@@ -0,0 +1,18 @@
+// The lanes scripts/ide_test.mjs runs (ide-test.bat). A lane is one scenario
+// file in this folder, run with node:test in a process of its own, with its own
+// DevTools port, work folder and copy of the twinBASIC install;
+// scripts/lib/tb-lane.mjs is what the file gets. A scenario file imports
+// `scenario` from "../addin/scenario.mjs", as the add-in ones do.
+//
+//   file      the scenario file
+//   name      what --only matches and the report calls the lane; by default
+//             the file's name without ".test.mjs"
+//   settings  every application name the lane's programs pass to SaveSetting.
+//             SaveSetting writes under HKCU\Software\VB and VBA Program
+//             Settings\<name>. The runner records those keys before the first
+//             lane starts, deletes them before this lane starts, and puts them
+//             back as found once every lane has ended. Two lanes that name the
+//             same one never run at once. Settings that are not named here are
+//             left changed after the run.
+
+export default [{ file: "export.test.mjs" }];
diff --git a/test/ide/probes/export/Settings b/test/ide/probes/export/Settings
new file mode 100644
index 00000000..281fe2b5
--- /dev/null
+++ b/test/ide/probes/export/Settings
@@ -0,0 +1,61 @@
+{
+	"configuration.inherits": "Defaults",
+	"project.appTitle": "ExportProbe",
+	"project.buildPath": "${SourcePath}\\Build\\${ProjectName}_${Architecture}.${FileExtension}",
+	"project.buildType": "Standard EXE",
+	"project.description": "test/ide/export.test.mjs opens it in a lane's copy of the install and exports it with the IDE's own Export Project, into folders inside the lane's work folder.",
+	"project.exportPathIsV2": true,
+	"project.id": "{7B247500-0000-4000-9000-7B2475000001}",
+	"project.name": "ExportProbe",
+	"project.optionExplicit": true,
+	"project.references": [
+		{
+			"id": "{00020430-0000-0000-C000-000000000046}",
+			"lcid": 0,
+			"name": "OLE Automation",
+			"path32": "C:\\Windows\\SysWOW64\\stdole2.tlb",
+			"path64": "C:\\Windows\\System32\\stdole2.tlb",
+			"symbolId": "stdole",
+			"versionMajor": 2,
+			"versionMinor": 0
+		},
+		{
+			"id": "{F50B82D0-DCAB-43FE-9631-11959D4A4728}",
+			"isCompilerPackage": true,
+			"licence": "MIT",
+			"name": "[COMPILER PACKAGE] twinBASIC - VB Compatibility Package (Forms)",
+			"path32": "",
+			"path64": "",
+			"publisher": "TWINBASIC-COMPILER",
+			"symbolId": "VB",
+			"versionBuild": 0,
+			"versionMajor": 0,
+			"versionMinor": 0,
+			"versionRevision": 31
+		},
+		{
+			"id": "{C192FB39-64CA-4D9B-B477-A5502F48EFCC}",
+			"isCompilerPackage": true,
+			"licence": "MIT",
+			"name": "[COMPILER PACKAGE] twinBASIC - App global class object",
+			"path32": "",
+			"path64": "",
+			"publisher": "TWINBASIC-COMPILER",
+			"symbolId": "AppGlobalClassProject",
+			"versionBuild": 0,
+			"versionMajor": 1,
+			"versionMinor": 0,
+			"versionRevision": 0
+		}
+	],
+	"project.settingsVersion": 1,
+	"project.startupObject": "Sub Main",
+	"project.warnings": {
+		"errors": [],
+		"hints": [],
+		"ignored": [],
+		"info": [],
+		"warnings": []
+	},
+	"runtime.useUnicodeStandardLibrary": true
+}
diff --git a/test/ide/probes/export/Sources/Startup.twin b/test/ide/probes/export/Sources/Startup.twin
new file mode 100644
index 00000000..b563b576
--- /dev/null
+++ b/test/ide/probes/export/Sources/Startup.twin
@@ -0,0 +1,5 @@
+' The project test/ide/export.test.mjs exports. It is never run.
+Module Startup
+    Public Sub Main()
+    End Sub
+End Module

From ccb46975621d39a287241377e24140621cdc3ece Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 12:35:57 +0200
Subject: [PATCH 05/22] docs, bugs: >> is arithmetic since BETA 984; BUGS
 entries re-run on BETA 995

---
 BUGS-TO-REPORT.md                 | 106 ++++++++++--------------------
 docs/Reference/Core/RightShift.md |  14 ++--
 2 files changed, 40 insertions(+), 80 deletions(-)

diff --git a/BUGS-TO-REPORT.md b/BUGS-TO-REPORT.md
index 98f495f1..69b95b04 100644
--- a/BUGS-TO-REPORT.md
+++ b/BUGS-TO-REPORT.md
@@ -62,7 +62,7 @@ opens then trips this.
 
 ## Compiler crashes on an `Interface` named by an angle-bracket placeholder that has an `Extends` clause
 
-**Build:** BETA 983 (`twinBASIC_win32.dll+00141F7A`)
+**Build:** BETA 995; BETA 983 at `twinBASIC_win32.dll+00141F7A`
 **Severity:** crash --- takes the compiler down, three restarts, then the IDE gives up.
 
 This two-line file is the whole reproduction:
@@ -101,7 +101,7 @@ costs the whole batch its result, which is why that tool isolates the sample on
 
 ## An `Interface` that extends itself compiles without a diagnostic
 
-**Build:** BETA 983
+**Build:** BETA 995
 **Severity:** invalid code accepted --- the same cycle through a class is refused.
 
 This two-line file compiles with no error, warning, hint or info:
@@ -154,7 +154,7 @@ records the same measurements.
 
 ## Public members are typed with Private components, so a default project cannot use them
 
-**Build:** BETA 983
+**Build:** BETA 995
 **Severity:** documented APIs need the consumer to expose the package's internals; one
 event asks for a type it then refuses.
 
@@ -250,7 +250,7 @@ compiled in a default project.
 
 ## `Err.Raise` rejects `HelpContext` as a named argument, while its three siblings work
 
-**Build:** BETA 983
+**Build:** BETA 995
 **Severity:** VBA-compatible code that names the fifth argument does not compile, and the
 diagnostic does not say which name was wrong.
 
@@ -293,7 +293,7 @@ whose sample was written in the named form. The page uses the positional form no
 
 ## An interface member marked `[PreserveSig]` cannot be implemented by a class
 
-**Build:** BETA 983
+**Build:** BETA 995
 **Severity:** an interface the language lets you declare cannot be implemented at all, and
 the diagnostic asks for the signature that is already written.
 
@@ -313,9 +313,11 @@ End Class
 
 ```
 TB5004 unable to match this implementation to its interface member. The expected signature was: Private Function IProbeD_F() As Long
-TB5000 Missing implementation of member Function F() As Long
+TB65535 Missing implementation of member Function F() As Long
 ```
 
+BETA 983 gave the second message as TB5000.
+
 **The "expected" signature is character for character the one on the line the error is
 reported against.** Whatever the compiler is comparing, it is not what it prints.
 
@@ -548,44 +550,9 @@ cause.
 
 ---
 
-## `\` and `Mod` on the most negative `Integer` or `Long` by -1 raise a native exception that `On Error` cannot handle
-
-**Build:** BETA 983, 32-bit target
-**Severity:** a division that should raise the trappable error 6 stops the procedure instead; the
-`LongLong` form returns a wrong value with no error at all.
-
-```
-Dim a As Integer = -32768
-Dim b As Integer = -1
-On Error Resume Next
-Debug.Print a \ b
-```
-
-The DEBUG CONSOLE shows `NATIVE EXCEPTION: NT_OVERFLOW /<file>; <module>.<procedure> LINE <n>
-[CONTINUABLE]` for the division's line, then `[IDE] auto-activated TRACE-MODE in this session`,
-and nothing after that line runs, `On Error Resume Next` notwithstanding.
-
-| operands | `\` | `Mod` |
-|---|---|---|
-| `Integer` -32768 and -1 | native exception | native exception |
-| `Long` -2147483648 and -1 | native exception | native exception |
-| `LongLong` -9223372036854775808 and -1 | **-9223372036854775808**, no error | 0 (right) |
-| a `Variant` holding the `Integer` -32768, and -1 | `Long` 32768 (right) | --- |
-| a `Variant` holding the `Long` -2147483648, and -1 | error 6 (right) | --- |
-
-**What does not reproduce it:** every other overflow measured raises error 6 as it should ---
-`32767 + 1`, `32767 * 32767` and `-(-32768)` on typed `Integer` values, and the same kind of
-overflow on `Long`, `LongLong`, `Single`, `Double`, `Currency` and `Decimal` --- and division by
-zero raises error 11. Only the one quotient that does not fit its type fails this way.
-
-**Found by** probing the arithmetic operators' result types for `Reference/Operators.md`. The
-probe's first run lost every case after this one.
-
----
-
 ## Shifting a `Single`, `Double`, `Date`, `Boolean` or `String` compiles clean, then fails code generation
 
-**Build:** BETA 983
+**Build:** BETA 995
 **Severity:** the compiler accepts the expression with no diagnostic, and the procedure that
 contains it never runs.
 
@@ -616,26 +583,15 @@ floating-point operands are truncated before shifting.
 
 ---
 
-## `>>` gives three different results for the same value, and a `Variant` shift can return `Empty`
+## A `Variant` shift multiplies a fractional value, and can return `Empty`
 
-**Build:** BETA 983
+**Build:** BETA 995
 **Severity:** wrong values, with no diagnostic.
 
-```
-Dim n As Long = -8
-Dim v As Variant = CLng(-8)
-Debug.Print -8& >> 1    ' -4           constants: an arithmetic shift
-Debug.Print n >> 1      ' 2147483644   a Long variable: a logical shift
-Debug.Print v >> 1      ' -4           a Variant: a division, truncated toward zero
-```
-
-The logical shift is what a typed variable gets and what the documentation describes. The
-constant folder disagrees with the code generator: `-1 >> 1` and `-1& >> 1` are both -1, where an
-`Integer` variable holding -1 gives 32767 and a `Long` variable gives 2147483647.
-
-A `Variant` operand is not shifted but multiplied or divided --- a `Variant` holding the `Double`
-7.9, shifted left by 1, is 15.8 --- and a count as large as the width of the type it holds gives
-`Empty` rather than 0:
+A `Variant` holding the `Double` 7.9, shifted left by 1, is 15.8: the value is multiplied, not
+shifted, and so is a `Currency` or `Decimal` holding 7.9. Shifted right by 1, the `Variant` and
+the `Decimal` give 3 but the `Currency` gives 3.95. A count as large as the width of the type the `Variant` holds gives `Empty` rather
+than 0:
 
 | expression | result |
 |---|---|
@@ -644,14 +600,15 @@ A `Variant` operand is not shifted but multiplied or divided --- a `Variant` hol
 | a `Variant` holding `CLng(1)`, `<< 31` | `Long` -2147483648 |
 | a `Long` variable holding 1, `<< 32` | 0 |
 
-**Found by** probing the operators for `Reference/Core/LeftShift.md` and `RightShift.md`, whose
-examples said `-1 >> 1` returns `&H7FFFFFFF`. It returns -1.
+**Found by** probing the operators for `Reference/Core/LeftShift.md` and `RightShift.md`. The
+same probe found `>>` logical on a typed variable and arithmetic on a constant, up to BETA 983;
+BETA 984 made both arithmetic.
 
 ---
 
 ## Overloads on `Date` and `Double` resolve by declaration order, not by the argument's type
 
-**Build:** BETA 983
+**Build:** BETA 995
 **Severity:** the wrong overload runs, with no diagnostic.
 
 ```
@@ -684,7 +641,7 @@ measuring the operators for `Reference/Operators.md`.
 
 ## `Boolean \ String` and `Boolean Mod String` convert the `String` to `Boolean`
 
-**Build:** BETA 983
+**Build:** BETA 995
 **Severity:** a wrong value and a wrong type, with no diagnostic.
 
 ```
@@ -711,7 +668,7 @@ the other way round: `"2" \ b` is the `Long` -2.
 
 ## Export Project follows a directory junction in its folder and deletes what it points to
 
-**Build:** BETA 983
+**Build:** BETA 995 (`ide-test.bat`'s `export` lane asserts it)
 **Severity:** data loss outside the folder the user chose. Export Project empties its folder
 before writing, as the *Export Path* setting warns; it does not stop at a junction.
 
@@ -734,7 +691,7 @@ before writing, as the *Export Path* setting warns; it does not stop at a juncti
 
 ## Export Project stops at a read-only file after deleting everything before it, and the IDE reports nothing
 
-**Build:** BETA 983
+**Build:** BETA 995 (`ide-test.bat`'s `export` lane asserts it)
 **Severity:** a partly emptied folder, with the only record in the Debug Console. On a Git
 working copy it breaks the repository, because Git makes its object files read-only.
 
@@ -946,7 +903,10 @@ choosing **Run → End** makes it an ordinary break, and the run is aborted (two
 
 ## A `Static` declaration cannot initialise with a constructor that takes arguments
 
-**Build:** BETA 983
+**Build:** BETA 983 --- **not reproduced on a re-check**: a `Static s As Dog = New Dog("Rex")`,
+in a Module procedure, a Function, a Class method and a Property Get, with `Dog` a Private or a
+`[COMCreatable(False)]` class with a one-parameter `Sub New`, compiled and ran on BETA 983 and
+995 alike. What else the original case held is not recorded; find it before filing.
 **Severity:** a valid declaration does not compile; the workaround is a `Static` without an
 initialiser and a `Set` on first use.
 
@@ -1015,7 +975,7 @@ and v2 runs at once.
 
 ## An error in the body of a generic procedure names neither the type nor the call that caused it
 
-**Build:** BETA 983
+**Build:** BETA 995
 **Severity:** a diagnostic that points at correct code. In a project with many calls to a
 generic procedure, nothing says which call to fix.
 
@@ -1046,7 +1006,7 @@ nothing to say which types it accepts.
 
 ## Text that continues a `Debug.Print` line is escaped twice in the DEBUG CONSOLE
 
-**Build:** BETA 983
+**Build:** BETA 995
 **Severity:** cosmetic, but it changes what a program appears to print: `&`, `<` and `>` in
 the continued part of a line show as `&amp;`, `&lt;` and `&gt;`.
 
@@ -1084,7 +1044,7 @@ that the IDE appends to an open console line.
 
 ## An add-in's keyboard shortcut does not fire if it includes `{CTRL}` or `{ALT}`
 
-**Build:** BETA 983
+**Build:** BETA 995 (`addin-test.bat`'s `keys` lane asserts it)
 **Severity:** the SDK's own example, `{CTRL}{SHIFT}d` in `KeyboardShortcuts.Add`'s
 description, cannot be used, and nothing says why.
 
@@ -1123,7 +1083,7 @@ key events and checks each result. Every case in the table is a test in that lan
 
 ## F1 and the fold icon toggle the signature help, then fail
 
-**Build:** BETA 983
+**Build:** BETA 995 for F1 (`addin-test.bat`'s `keys` lane asserts it); BETA 983 for the fold icon
 **Severity:** cosmetic --- the toggle works, but every F1 adds `command failed:
 "tbHelp_ToggleExpandSignatureHelp"` to the DEBUG CONSOLE, and every click on the icon throws
 in the page.
@@ -1183,7 +1143,7 @@ opening a file (`afterReveal` in `scripts/lib/tb-operate.mjs`).
 
 ## Hover says a `ByVal` parameter was auto-generated because `Option Explicit` is off
 
-**Build:** BETA 983
+**Build:** BETA 995 (`addin-test.bat`'s `symbols` lane asserts it)
 **Severity:** cosmetic, but it tells the user to turn on an option that is already on, over
 a parameter they declared.
 
@@ -1224,7 +1184,7 @@ checks every row of the table). The text is the markdown the IDE's hover shows.
 
 ## Every tool window given no id is the same window
 
-**Build:** BETA 983
+**Build:** BETA 995 (`addin-test.bat`'s `panes` lane asserts it)
 **Severity:** an add-in's windows overwrite each other, or another add-in's, and nothing
 says so. The id is declared `Optional`, so leaving it out looks correct.
 
@@ -1259,7 +1219,7 @@ IDE's add-in samples leaves the id out.
 
 ## `[PopulateFrom]` with no arguments crashes the compiler
 
-**Build:** BETA 987
+**Build:** BETA 995; first seen on BETA 987
 **Severity:** the compiler process dies while the project is being parsed, which
 `tbbuild` reports as a crash (its exit code 4), so a person who forgets the arguments is not
 told what is missing.
diff --git a/docs/Reference/Core/RightShift.md b/docs/Reference/Core/RightShift.md
index 2bc7347c..9aee0297 100644
--- a/docs/Reference/Core/RightShift.md
+++ b/docs/Reference/Core/RightShift.md
@@ -7,7 +7,7 @@ permalink: /tB/Core/RightShift
 # \>> and \>>= operators
 {: .no_toc #rightshift-operators }
 
-*(twinBASIC)* Shifts the bits of a numeric value right by a given number of positions, filling vacated high-order bits with zero. The compound form **>>=** shifts-and-assigns in one step.
+*(twinBASIC)* Shifts the bits of a numeric value right by a given number of positions, keeping the sign of a signed value. The compound form **>>=** shifts-and-assigns in one step.
 
 > [!NOTE]
 > **\>>** and **\>>=** are twinBASIC extensions. Classic VBA has no bitshift operators; equivalent code divides by powers of two with [**\\\\**](IntegerDivide) (`x \ 2`, `x \ 4`, …).
@@ -28,16 +28,16 @@ Syntax:
 *count*
 : Any numeric expression giving the number of bit positions to shift.
 
-The data type of *result* matches the type of *number*, whatever the type of *count*; shifts do not follow the [promotion rules](../../Reference/Operators#result-types-and-promotion) of the arithmetic operators. The right shift is *logical*, not arithmetic: vacated high-order bits are filled with zero, so a negative *number* becomes a large positive value rather than retaining its sign --- a **Long** variable holding -8, shifted right by 1, is 2147483644. A shift by as many bits as the type holds, or more, yields `0`. A negative *count* raises no error, but gives no useful result.
+The data type of *result* matches the type of *number*, whatever the type of *count*; shifts do not follow the [promotion rules](../../Reference/Operators#result-types-and-promotion) of the arithmetic operators. The right shift of an **Integer**, **Long**, **LongLong** or **LongPtr** is *arithmetic*: vacated high-order bits are copies of the sign bit, so a negative *number* stays negative --- a **Long** holding -8, shifted right by 1, is -4, and one holding -7 also gives -4, rounding toward negative infinity where [**\\**](IntegerDivide) rounds toward zero. A **Byte** has no sign, and its vacated bits are filled with zero. Constants and variables give the same result. A shift by as many bits as the type holds, or more, yields `0`. A negative *count* raises no error, but gives no useful result.
 
-> [!IMPORTANT]
-> When both operands are constants, the compiler evaluates **>>** as an *arithmetic* shift, which keeps the sign: `-8& >> 1` is -4 and `-1 >> 1` is -1. Hold a negative value in a variable when the logical shift is wanted.
+> [!NOTE]
+> Up to BETA 983, a variable was shifted *logically*, filling the vacated bits with zero, while constants were shifted arithmetically: a **Long** variable holding -8, shifted right by 1, gave 2147483644. BETA 984 made both arithmetic.
 
 > [!IMPORTANT]
 > Only the integral types are shifted bit by bit. With other types of *number*:
 >
-> - A **Currency** or **Decimal** is shifted as a value: a **Currency** holding 7.9, shifted right by 1, is 3.95, and a **Decimal** holding 7.9 gives 4.
-> - A **Variant** is divided as a value, truncating toward zero, so the sign is kept: a **Variant** holding the **Long** -8, shifted right by 1, is -4, and one holding -7 gives -3.
+> - A **Currency** is shifted as a value, fraction included: a **Currency** holding 7.9, shifted right by 1, is 3.95. A **Decimal** holding 7.9 gives 3.
+> - A **Variant** holding the **Long** -7, shifted right by 1, is -4, as the **Long** itself gives; one holding the **Double** 7.9 gives 3.
 > - A **Single**, **Double**, **Date**, **Boolean** or **String** compiles without a diagnostic, but the procedure containing the shift does not run: the IDE reports *compilation (codegen) error detected* at that line.
 >
 > Convert such a value with [**CLng**](../Modules/Conversion/CLng) or [**CLngLng**](../Modules/Conversion/CLngLng) before shifting it.
@@ -61,7 +61,7 @@ Value = 16 >> 4                 ' Returns 1.
 Value = 1024 >> 3               ' Returns 128.
 
 Dim Negative As Long = -1
-Value = Negative >> 1           ' Returns &H7FFFFFFF: the vacated bit is filled with 0.
+Value = Negative >> 1           ' Returns -1: the vacated bit is a copy of the sign bit.
 ```
 
 ### See Also

From e68a3d4e41ca2ce5c2c03ce2fae5be7c96d93ffb Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 12:43:30 +0200
Subject: [PATCH 06/22] test: ide-test.bat's debugger lane; Debug.md's two
 defects hold on BETA 995

---
 BUGS-TO-REPORT.md                             |   9 +-
 docs/IDE/Menu/Debug.md                        |   2 +-
 test/ide/debugger.test.mjs                    | 134 ++++++++++++++++++
 test/ide/lanes.mjs                            |   2 +-
 test/ide/probes/debugger/Settings             |  61 ++++++++
 test/ide/probes/debugger/Sources/Startup.twin |  20 +++
 6 files changed, 222 insertions(+), 6 deletions(-)
 create mode 100644 test/ide/debugger.test.mjs
 create mode 100644 test/ide/probes/debugger/Settings
 create mode 100644 test/ide/probes/debugger/Sources/Startup.twin

diff --git a/BUGS-TO-REPORT.md b/BUGS-TO-REPORT.md
index 69b95b04..9770c6cb 100644
--- a/BUGS-TO-REPORT.md
+++ b/BUGS-TO-REPORT.md
@@ -856,7 +856,7 @@ and as the built EXE, with identical results.
 
 ## A step key pressed on the line that raised an error leaves a step pending
 
-**Build:** BETA 983
+**Build:** BETA 995 (`ide-test.bat`'s `debugger` lane asserts it)
 **Severity:** the debugger stops where it was not asked to, and one command no longer means one
 thing.
 
@@ -867,8 +867,9 @@ thing.
    Moving past the line with **Set Next Statement** (CTRL+F9) instead, each F5 then advances
    one line.
 
-Seen in three runs. In the one followed to the end, it lasted until the procedure returned; in
-another, a fix-then-F5 stopped once. Which of the two applies was not isolated.
+In `ide-test.bat`'s `debugger` lane, on BETA 983 and 995 alike, the waiting step is used up by
+that one stop: the next F5 runs on to the loop's next error. An earlier run by hand, followed to
+the end, saw it last until the procedure returned; what differed there is not known.
 
 **What does not reproduce it:** choosing **Ignore** without pressing a step key first, which
 runs on from the next line as the panel says.
@@ -879,7 +880,7 @@ runs on from the next line as the panel says.
 
 ## Stop at a run-time error ends only the procedure that raised it
 
-**Build:** BETA 983
+**Build:** BETA 995 (`ide-test.bat`'s `debugger` lane asserts it); BETA 983 for the `Assert` case
 **Severity:** the program goes on running after the user asked it to stop.
 
 A `Sub Main` that calls a procedure which raises an untrapped error, and prints a line after
diff --git a/docs/IDE/Menu/Debug.md b/docs/IDE/Menu/Debug.md
index 65ec841a..f69ce63b 100644
--- a/docs/IDE/Menu/Debug.md
+++ b/docs/IDE/Menu/Debug.md
@@ -98,7 +98,7 @@ To run on to the end instead, correct the value and press <kbd>F5</kbd>, or pres
 - **A step key leaves a step waiting.** After <kbd>F8</kbd> on the failing line, **Ignore (Resume Next)** stops again on the next line instead of going on. Press <kbd>F5</kbd> to go on.
 - **At an error, Stop ends only the procedure that failed.** The procedure that called it goes on from its next line: if `Sub Main` called `FillTable`, the rest of `Sub Main` still runs. The panel's **Stop**, the toolbar's **Stop** and **Run → End** all do this. At a failed **Assert** check, **Stop** ends only the check, and the test goes on past it as if the check had passed. To end the whole run, first move the arrow to a later line with <kbd>CTRL</kbd> + <kbd>F9</kbd>, then press **Stop**. Away from an error --- at a breakpoint, after a step, or after Set Next Statement --- **Stop** ends the run.
 
-The last two are defects, as of BETA 983.
+The last two are defects, as of BETA 995.
 
 ## Debugger Options
 
diff --git a/test/ide/debugger.test.mjs b/test/ide/debugger.test.mjs
new file mode 100644
index 00000000..b806bdcf
--- /dev/null
+++ b/test/ide/debugger.test.mjs
@@ -0,0 +1,134 @@
+// The debugger at a run-time error, measured: what F8, Ignore (Resume Next)
+// and Stop do once the error panel is open, operated as a person does --- real
+// key presses and clicks on the panel's buttons. The project in
+// probes/debugger fails on every pass of a loop in FillTable, which Main
+// calls, and prints a line before and after each step, so the DEBUG CONSOLE
+// shows how far it got.
+//
+// Each test states what BETA 983 and 995 do. If one fails after an IDE update,
+// the IDE has changed: update the Traps on docs/IDE/Menu/Debug.md and the two
+// debugger entries in BUGS-TO-REPORT.md, and then this file.
+//
+// Run it with ide-test.bat, which gives it a lane; on its own it is skipped.
+
+import assert from "node:assert/strict";
+import { readFileSync } from "node:fs";
+import path from "node:path";
+import { before, test } from "node:test";
+import { fileURLToPath } from "node:url";
+import { consoleMark, linesSince } from "../../scripts/lib/tb-ide-console.mjs";
+import { click, pressKey, waitFor } from "../../scripts/lib/tb-operate.mjs";
+import { scenario } from "../addin/scenario.mjs";
+
+const HERE = path.dirname(fileURLToPath(import.meta.url));
+const PROJECT = path.join(HERE, "probes", "debugger");
+const SOURCE = readFileSync(path.join(PROJECT, "Sources", "Startup.twin"), "utf8").split(/\r?\n/);
+// The failing line, 1-based as the IDE counts it.
+const FAILS = SOURCE.findIndex((l) => l.includes("' FAILS")) + 1;
+const sleep = (ms) => new Promise((r) => setTimeout(r, ms));
+
+// What the debugger shows: whether it is paused and running, the line it is
+// paused on, and the error panel's buttons, which are there only at an error.
+const STATE_JS = `(() => ({
+  paused: !!context.atBreakpoint.value,
+  running: !!context.codeExecuting.value,
+  line: activeDebuggingLine,
+  panel: [...document.querySelectorAll(".errorWidgetButton")].map((b) => b.textContent.trim()),
+}))()`;
+const PANEL = ["Try Again (Resume)", "Ignore (Resume Next)", "Stop", "Search Online"];
+const atError = { paused: true, running: true, line: FAILS, panel: PANEL };
+
+scenario("the debugger at a run-time error", (lane) => {
+  let c;
+  let mark;
+  const state = () => c.evaluate(STATE_JS);
+  const printed = () => linesSince(c, mark);
+  const button = (text) => click(c, { css: ".errorWidgetButton", text });
+
+  // Start a run from the editor, as F5 does, and wait for the panel.
+  async function runToError() {
+    mark = await consoleMark(c);
+    await c.evaluate(`executeIdeCommand("tbDebug_StartOrContinue")`);
+    assert.ok(await waitFor(c, async () => (await state()).panel.length, { timeout: 60 * 1000 }), "no error panel");
+    assert.deepEqual(await state(), atError);
+  }
+  // Wait out a command: the IDE answers within a second; three is generous.
+  const settle = () => sleep(3000);
+  // End a run that is still going, so the next test starts from a stopped IDE.
+  async function stopIfRunning() {
+    if ((await state()).running) {
+      await c.evaluate(`executeIdeCommand("tbDebug_Stop")`);
+      assert.ok(await waitFor(c, async () => !(await state()).running), "the run did not stop");
+    }
+  }
+
+  before(async () => {
+    c = await lane.open(PROJECT);
+  });
+
+  test("F8 on the failing line runs it again: the error recurs and the mark stays", async () => {
+    await runToError();
+    await pressKey(c, "F8");
+    await settle();
+    assert.deepEqual(await state(), atError);
+    assert.deepEqual(await printed(), ["Executing 'Main'...", "main start", "loop 0"]);
+    await stopIfRunning();
+  });
+
+  test("after F8 there, Ignore stops on the next line instead of running on", async () => {
+    await runToError();
+    await pressKey(c, "F8");
+    await settle();
+    await button("Ignore (Resume Next)");
+    await settle();
+    assert.deepEqual(await state(), { paused: true, running: true, line: FAILS + 1, panel: [] });
+    assert.ok(!(await printed()).includes("after fail 0"), "Ignore ran on past the next line");
+    // One F5 then runs on, to the error on the loop's next pass: the step
+    // that was left waiting is used up by one stop.
+    await pressKey(c, "F5");
+    await settle();
+    assert.deepEqual(await state(), atError);
+    assert.deepEqual((await printed()).slice(-2), ["after fail 0", "loop 1"]);
+    await stopIfRunning();
+  });
+
+  test("Ignore with no step first runs on, to the next pass's error", async () => {
+    await runToError();
+    await button("Ignore (Resume Next)");
+    await settle();
+    assert.deepEqual(await state(), atError);
+    assert.deepEqual((await printed()).slice(-2), ["after fail 0", "loop 1"]);
+    await stopIfRunning();
+  });
+
+  test("the panel's Stop ends only the failing procedure: Main goes on", async () => {
+    await runToError();
+    await button("Stop");
+    assert.ok(await waitFor(c, async () => !(await state()).running), "the run did not stop");
+    const lines = await printed();
+    assert.ok(lines.includes("main after call"), "Main no longer goes on after Stop");
+    assert.ok(!lines.includes("fill end"));
+  });
+
+  // main.js binds the toolbar's stopIcon and the Run menu's End to this command.
+  test("the Stop command, as the toolbar and Run > End give it, does the same", async () => {
+    await runToError();
+    await c.evaluate(`executeIdeCommand("tbDebug_Stop")`);
+    assert.ok(await waitFor(c, async () => !(await state()).running), "the run did not stop");
+    assert.ok((await printed()).includes("main after call"), "Main no longer goes on after Stop");
+  });
+
+  test("Stop at an ordinary break ends the whole run", async () => {
+    await runToError();
+    await pressKey(c, "F8");
+    await settle();
+    await button("Ignore (Resume Next)");
+    await settle();
+    assert.deepEqual((await state()).panel, [], "not at an ordinary break");
+    await c.evaluate(`executeIdeCommand("tbDebug_Stop")`);
+    assert.ok(await waitFor(c, async () => !(await state()).running), "the run did not stop");
+    const lines = await printed();
+    assert.ok(!lines.includes("main after call"), "Main went on after Stop at a break");
+    assert.ok(lines.includes("aborted"), "no 'aborted' line");
+  });
+});
diff --git a/test/ide/lanes.mjs b/test/ide/lanes.mjs
index f8183173..e9674db4 100644
--- a/test/ide/lanes.mjs
+++ b/test/ide/lanes.mjs
@@ -15,4 +15,4 @@
 //             same one never run at once. Settings that are not named here are
 //             left changed after the run.
 
-export default [{ file: "export.test.mjs" }];
+export default [{ file: "export.test.mjs" }, { file: "debugger.test.mjs" }];
diff --git a/test/ide/probes/debugger/Settings b/test/ide/probes/debugger/Settings
new file mode 100644
index 00000000..fe9013a4
--- /dev/null
+++ b/test/ide/probes/debugger/Settings
@@ -0,0 +1,61 @@
+{
+	"configuration.inherits": "Defaults",
+	"project.appTitle": "DebuggerProbe",
+	"project.buildPath": "${SourcePath}\\Build\\${ProjectName}_${Architecture}.${FileExtension}",
+	"project.buildType": "Standard EXE",
+	"project.description": "test/ide/debugger.test.mjs opens it in a lane's copy of the install, runs it in the debugger, and operates the error panel when it fails.",
+	"project.exportPathIsV2": true,
+	"project.id": "{7B247500-0000-4000-9000-7B2475000002}",
+	"project.name": "DebuggerProbe",
+	"project.optionExplicit": true,
+	"project.references": [
+		{
+			"id": "{00020430-0000-0000-C000-000000000046}",
+			"lcid": 0,
+			"name": "OLE Automation",
+			"path32": "C:\\Windows\\SysWOW64\\stdole2.tlb",
+			"path64": "C:\\Windows\\System32\\stdole2.tlb",
+			"symbolId": "stdole",
+			"versionMajor": 2,
+			"versionMinor": 0
+		},
+		{
+			"id": "{F50B82D0-DCAB-43FE-9631-11959D4A4728}",
+			"isCompilerPackage": true,
+			"licence": "MIT",
+			"name": "[COMPILER PACKAGE] twinBASIC - VB Compatibility Package (Forms)",
+			"path32": "",
+			"path64": "",
+			"publisher": "TWINBASIC-COMPILER",
+			"symbolId": "VB",
+			"versionBuild": 0,
+			"versionMajor": 0,
+			"versionMinor": 0,
+			"versionRevision": 31
+		},
+		{
+			"id": "{C192FB39-64CA-4D9B-B477-A5502F48EFCC}",
+			"isCompilerPackage": true,
+			"licence": "MIT",
+			"name": "[COMPILER PACKAGE] twinBASIC - App global class object",
+			"path32": "",
+			"path64": "",
+			"publisher": "TWINBASIC-COMPILER",
+			"symbolId": "AppGlobalClassProject",
+			"versionBuild": 0,
+			"versionMajor": 1,
+			"versionMinor": 0,
+			"versionRevision": 0
+		}
+	],
+	"project.settingsVersion": 1,
+	"project.startupObject": "Sub Main",
+	"project.warnings": {
+		"errors": [],
+		"hints": [],
+		"ignored": [],
+		"info": [],
+		"warnings": []
+	},
+	"runtime.useUnicodeStandardLibrary": true
+}
diff --git a/test/ide/probes/debugger/Sources/Startup.twin b/test/ide/probes/debugger/Sources/Startup.twin
new file mode 100644
index 00000000..0aec2c23
--- /dev/null
+++ b/test/ide/probes/debugger/Sources/Startup.twin
@@ -0,0 +1,20 @@
+' The project test/ide/debugger.test.mjs runs in the debugger. FillTable fails
+' on every pass of its loop, at the line marked FAILS; each line around it
+' prints, so the DEBUG CONSOLE shows how far the program got.
+Module Startup
+    Public Sub Main()
+        Debug.Print "main start"
+        FillTable
+        Debug.Print "main after call"
+    End Sub
+
+    Private Sub FillTable()
+        Dim a(3) As Long, i As Long, idx As Long = 5
+        For i = 0 To 2
+            Debug.Print "loop " & i
+            a(idx) = i ' FAILS
+            Debug.Print "after fail " & i
+        Next
+        Debug.Print "fill end"
+    End Sub
+End Module

From 7ef60f3d02ccf31c84b61d8a1deee920ecceee92 Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 13:12:59 +0200
Subject: [PATCH 07/22] test: ide-test.bat's packages lane; an imported package
 is still unticked on BETA 995

---
 BUGS-TO-REPORT.md                             |   5 +-
 ...mporting a package from a TWINPACK file.md |   2 +-
 docs/Features/Packages/Updating a package.md  |   2 +-
 test/ide/lanes.mjs                            |   2 +-
 test/ide/packages.test.mjs                    | 109 ++++++++++++++++++
 test/ide/probes/packages/DocProbePkg/Settings |  21 ++++
 .../DocProbePkg/Sources/DocProbe.twin         |   6 +
 test/ide/probes/packages/host/Settings        |  61 ++++++++++
 .../probes/packages/host/Sources/Startup.twin |   5 +
 9 files changed, 208 insertions(+), 5 deletions(-)
 create mode 100644 test/ide/packages.test.mjs
 create mode 100644 test/ide/probes/packages/DocProbePkg/Settings
 create mode 100644 test/ide/probes/packages/DocProbePkg/Sources/DocProbe.twin
 create mode 100644 test/ide/probes/packages/host/Settings
 create mode 100644 test/ide/probes/packages/host/Sources/Startup.twin

diff --git a/BUGS-TO-REPORT.md b/BUGS-TO-REPORT.md
index 9770c6cb..01502aad 100644
--- a/BUGS-TO-REPORT.md
+++ b/BUGS-TO-REPORT.md
@@ -937,7 +937,7 @@ no arguments (`Static c As Collection = New Collection`); and a `Static` of a va
 
 ## *Import from file...* leaves the imported package unticked
 
-**Build:** BETA 983
+**Build:** BETA 995 (`ide-test.bat`'s `packages` lane asserts it); BETA 983 by hand
 **Severity:** the package is imported but not referenced, and the documentation says it is.
 
 Settings → References → Available Packages → *Import from file...*, and choose a `.twinpack`. The
@@ -945,7 +945,8 @@ compiler answers the IDE's `importPackage` request with
 `success: true, body: { packageSymbol: "DocProbePkg" }`, and the package appears in the list
 unticked, so nothing in the project can use it until it is ticked by hand.
 `packageLoadFromFile` in `ide/main.js` reads `packageSymbol` from the response itself rather
-than from its `body`, which is consistent with what is seen; that part is read, not traced.
+than from its `body`, while the online import path beside it, `importPackage`, reads
+`t.body.packageSymbol`.
 
 **Found by** the package probe for round 8's UC-60, which drove the import over DevTools with
 the file's path in place of the native picker.
diff --git a/docs/Features/Packages/Importing a package from a TWINPACK file.md b/docs/Features/Packages/Importing a package from a TWINPACK file.md
index f66484cb..168eff20 100644
--- a/docs/Features/Packages/Importing a package from a TWINPACK file.md	
+++ b/docs/Features/Packages/Importing a package from a TWINPACK file.md	
@@ -20,7 +20,7 @@ To import a package directly from a TWINPACK file (instead of using TWINSERV), f
 ![Numbered callouts on the Project Settings icon, the Library References section and the Available Packages tab](Images/d9f1e4d9-1805-47e5-93aa-251151b4e914.png)
 - press the **Import from file...** button:
 ![A callout marking the Import from file button below the Available Packages list](Images/e35d5955-9e70-4d6e-abd7-748558da75ba.png)
-- choose the TWINPACK file you want to import. The package is added to the **Available Packages** list, but BETA 983 does not tick it: tick it yourself. It then appears, ticked, on the **Enabled Libraries** tab:
+- choose the TWINPACK file you want to import. The package is added to the **Available Packages** list, but BETA 995 does not tick it: tick it yourself. It then appears, ticked, on the **Enabled Libraries** tab:
 ![The Enabled Libraries list with the imported CSharpishStringFormater and FilePropertyExplorer packages ticked](Images/4e4b8e4d-2a1c-42e5-8f4b-5a9b3f523ee8.png)
 - press **Apply Changes**
 
diff --git a/docs/Features/Packages/Updating a package.md b/docs/Features/Packages/Updating a package.md
index 30ba7567..6c529cb0 100644
--- a/docs/Features/Packages/Updating a package.md	
+++ b/docs/Features/Packages/Updating a package.md	
@@ -65,7 +65,7 @@ So the old copy has to be removed first:
 
 1. Open [Project Settings](../../tB/IDE/Project/Settings#library-references). Under **Library References**, on the **Enabled Libraries** tab, untick the package, and press **Apply Changes**. The IDE saves the project and restarts the compiler.
 2. Open Project Settings again. On the **Available Packages** tab, press **Import from file...** and choose the new `.twinpack` file.
-3. Tick the package in the **Available Packages** list. BETA 983 adds the imported package to the list but does not tick it.
+3. Tick the package in the **Available Packages** list. BETA 995 adds the imported package to the list but does not tick it.
 4. Press **Apply Changes** again. The project now uses the new build.
 
 > [!WARNING]
diff --git a/test/ide/lanes.mjs b/test/ide/lanes.mjs
index e9674db4..5e057b6e 100644
--- a/test/ide/lanes.mjs
+++ b/test/ide/lanes.mjs
@@ -15,4 +15,4 @@
 //             same one never run at once. Settings that are not named here are
 //             left changed after the run.
 
-export default [{ file: "export.test.mjs" }, { file: "debugger.test.mjs" }];
+export default [{ file: "export.test.mjs" }, { file: "debugger.test.mjs" }, { file: "packages.test.mjs" }];
diff --git a/test/ide/packages.test.mjs b/test/ide/packages.test.mjs
new file mode 100644
index 00000000..903f8fbb
--- /dev/null
+++ b/test/ide/packages.test.mjs
@@ -0,0 +1,109 @@
+// Settings > References > Available Packages > Import from file..., measured:
+// what the IDE does with a .twinpack chosen there. The package, DocProbePkg in
+// probes/packages, is packed by scripts/impexp.mjs, and is imported into the
+// project in probes/packages/host by clicking the dialog's own button.
+//
+// The button opens a native file picker, which a lane cannot see. So for the
+// click only, the page's hostAppObject answers OpenPackage with the file's
+// path, and HostReadFileDataBase64 hands over the file's bytes read here. Both
+// stubs go in after the References page has loaded, because the compiler reads
+// the built-in packages through HostReadFileDataBase64 while it loads; a stub
+// in place then gives it the wrong bytes, and it stops at a run-time error box
+// that nobody sees. OpenPackage puts the real hostAppObject back as it answers,
+// and every other read goes to the real HostReadFileDataBase64.
+//
+// Each test states what BETA 995 does, which is what BETA 983 did by hand. In
+// a lane, BETA 983's References page never finishes loading, so this file
+// cannot run against it. If a test fails after an IDE update,
+// the IDE has changed: update the matching entry in BUGS-TO-REPORT.md and the
+// two Packages pages under docs/Features/Packages, and then this file.
+//
+// Run it with ide-test.bat, which gives it a lane; on its own it is skipped.
+
+import assert from "node:assert/strict";
+import { execFileSync } from "node:child_process";
+import { readFileSync } from "node:fs";
+import path from "node:path";
+import { before, test } from "node:test";
+import { fileURLToPath } from "node:url";
+import { click, waitFor } from "../../scripts/lib/tb-operate.mjs";
+import { scenario } from "../addin/scenario.mjs";
+
+const HERE = path.dirname(fileURLToPath(import.meta.url));
+const REPO = path.resolve(HERE, "..", "..");
+const HOST = path.join(HERE, "probes", "packages", "host");
+const PKG = path.join(HERE, "probes", "packages", "DocProbePkg");
+
+// The open Settings editor's working copy of the project's settings.
+const CONFIG_JS = `[...document.querySelectorAll("*")].find((e) => e.globalVars?.configData)?.globalVars`;
+// The compiler's requests still waiting for an answer.
+const WAITING_JS = `Object.keys(debugSocket.requestsAwaitingResponse).length`;
+
+// The picker and the file read, answered for one file; and the compiler's
+// answer to the import, recorded.
+const stubsJs = (pack, base64) => `(() => {
+  const real = hostAppObject;
+  hostAppObject = new Proxy(real, {
+    get: (t, p) => p === "OpenPackage"
+      ? () => { hostAppObject = real; return Promise.resolve(${JSON.stringify(pack)}); }
+      : (typeof t[p] === "function" ? t[p].bind(t) : t[p]),
+  });
+  const read = HostReadFileDataBase64;
+  HostReadFileDataBase64 = function (p, cb) {
+    if (p !== ${JSON.stringify(pack)}) return read.apply(this, arguments);
+    HostReadFileDataBase64 = read;
+    cb(${JSON.stringify(base64)});
+  };
+  window.__importAnswers = [];
+  const request = debugSocket.request;
+  debugSocket.request = function (name, args, cb) {
+    if (name !== "importPackage") return request.apply(this, arguments);
+    debugSocket.request = request;
+    return request.call(this, name, args, (m) => { window.__importAnswers.push(JSON.parse(JSON.stringify(m))); return cb(m); });
+  };
+  return true;
+})()`;
+
+scenario("Import from file... in the Packages dialog", (lane) => {
+  let c;
+  let pack;
+
+  before(async () => {
+    pack = path.join(lane.work, "DocProbePkg.twinpack");
+    execFileSync(process.execPath, [path.join(REPO, "scripts", "impexp.mjs"), "import", pack, PKG], { stdio: "pipe" });
+    c = await lane.open(HOST);
+  });
+
+  test("the imported package is listed, but not ticked", async () => {
+    await c.evaluate(`executeIdeCommand("tbProject_ShowReferences"), null`);
+    assert.ok(await waitFor(c, (c) => c.evaluate(`!!${CONFIG_JS}`), { timeout: 20 * 1000 }), "no Settings editor");
+    assert.ok(
+      await waitFor(c, async () => (await c.evaluate(WAITING_JS)) === 0, { timeout: 60 * 1000 }),
+      "the References page never finished loading",
+    );
+    await click(c, { css: "div", text: "Available Packages" });
+    await c.evaluate(stubsJs(pack, readFileSync(pack).toString("base64")));
+    await click(c, { css: "div", text: "Import from file..." });
+
+    const answers = await waitFor(c, async () => {
+      const a = await c.evaluate("window.__importAnswers");
+      return a.length ? a : null;
+    });
+    assert.ok(answers, "the compiler never answered the import");
+    // The compiler puts the symbol in the answer's body; the dialog's handler,
+    // packageLoadFromFile in main.js, reads it from the answer itself.
+    assert.equal(answers[0].success, true);
+    assert.deepEqual(answers[0].body, { packageSymbol: "DocProbePkg" });
+
+    const listed = await waitFor(c, (c) =>
+      c.evaluate(
+        `[...document.querySelectorAll(".referencesListRow .referencesListColSymbol")].some((e) => e.textContent.trim() === "DocProbePkg")`,
+      ),
+    );
+    assert.ok(listed, "DocProbePkg is not in the Available Packages list");
+    const referenced = await c.evaluate(
+      `${CONFIG_JS}.configData["project.references"].map((r) => r.symbolId ?? r.name)`,
+    );
+    assert.ok(!referenced.includes("DocProbePkg"), "the imported package is now ticked");
+  });
+});
diff --git a/test/ide/probes/packages/DocProbePkg/Settings b/test/ide/probes/packages/DocProbePkg/Settings
new file mode 100644
index 00000000..11d0503a
--- /dev/null
+++ b/test/ide/probes/packages/DocProbePkg/Settings
@@ -0,0 +1,21 @@
+{
+	"configuration.inherits": "Defaults",
+	"project.buildPath": "${SourcePath}\\Build\\${ProjectName}_${Architecture}.${FileExtension}",
+	"project.buildType": "Package TWINPACK",
+	"project.description": "test/ide/packages.test.mjs packs this folder into DocProbePkg.twinpack with scripts/impexp.mjs and imports it into probes/packages/host.",
+	"project.id": "{7B247500-0000-4000-9000-7B2475000004}",
+	"project.licence": "MIT",
+	"project.name": "DocProbePkg",
+	"project.optionExplicit": true,
+	"project.packageVisibility": "PUBLIC",
+	"project.references": [],
+	"project.versionBuild": 0,
+	"project.versionMajor": 1,
+	"project.versionMinor": 0,
+	"project.versionRevision": 0,
+	"project.warnings": {
+		"errors": [],
+		"ignored": []
+	},
+	"runtime.useUnicodeStandardLibrary": true
+}
diff --git a/test/ide/probes/packages/DocProbePkg/Sources/DocProbe.twin b/test/ide/probes/packages/DocProbePkg/Sources/DocProbe.twin
new file mode 100644
index 00000000..2d87d7a4
--- /dev/null
+++ b/test/ide/probes/packages/DocProbePkg/Sources/DocProbe.twin
@@ -0,0 +1,6 @@
+' The package test/ide/packages.test.mjs imports.
+Module DocProbe
+    Public Function DocProbeVersion() As Long
+        Return 1
+    End Function
+End Module
diff --git a/test/ide/probes/packages/host/Settings b/test/ide/probes/packages/host/Settings
new file mode 100644
index 00000000..5c2bb7a9
--- /dev/null
+++ b/test/ide/probes/packages/host/Settings
@@ -0,0 +1,61 @@
+{
+	"configuration.inherits": "Defaults",
+	"project.appTitle": "PackagesProbe",
+	"project.buildPath": "${SourcePath}\\Build\\${ProjectName}_${Architecture}.${FileExtension}",
+	"project.buildType": "Standard EXE",
+	"project.description": "test/ide/packages.test.mjs opens it in a lane's copy of the install and imports DocProbePkg into it through Settings, References.",
+	"project.exportPathIsV2": true,
+	"project.id": "{7B247500-0000-4000-9000-7B2475000003}",
+	"project.name": "PackagesProbe",
+	"project.optionExplicit": true,
+	"project.references": [
+		{
+			"id": "{00020430-0000-0000-C000-000000000046}",
+			"lcid": 0,
+			"name": "OLE Automation",
+			"path32": "C:\\Windows\\SysWOW64\\stdole2.tlb",
+			"path64": "C:\\Windows\\System32\\stdole2.tlb",
+			"symbolId": "stdole",
+			"versionMajor": 2,
+			"versionMinor": 0
+		},
+		{
+			"id": "{F50B82D0-DCAB-43FE-9631-11959D4A4728}",
+			"isCompilerPackage": true,
+			"licence": "MIT",
+			"name": "[COMPILER PACKAGE] twinBASIC - VB Compatibility Package (Forms)",
+			"path32": "",
+			"path64": "",
+			"publisher": "TWINBASIC-COMPILER",
+			"symbolId": "VB",
+			"versionBuild": 0,
+			"versionMajor": 0,
+			"versionMinor": 0,
+			"versionRevision": 31
+		},
+		{
+			"id": "{C192FB39-64CA-4D9B-B477-A5502F48EFCC}",
+			"isCompilerPackage": true,
+			"licence": "MIT",
+			"name": "[COMPILER PACKAGE] twinBASIC - App global class object",
+			"path32": "",
+			"path64": "",
+			"publisher": "TWINBASIC-COMPILER",
+			"symbolId": "AppGlobalClassProject",
+			"versionBuild": 0,
+			"versionMajor": 1,
+			"versionMinor": 0,
+			"versionRevision": 0
+		}
+	],
+	"project.settingsVersion": 1,
+	"project.startupObject": "Sub Main",
+	"project.warnings": {
+		"errors": [],
+		"hints": [],
+		"ignored": [],
+		"info": [],
+		"warnings": []
+	},
+	"runtime.useUnicodeStandardLibrary": true
+}
diff --git a/test/ide/probes/packages/host/Sources/Startup.twin b/test/ide/probes/packages/host/Sources/Startup.twin
new file mode 100644
index 00000000..acffff25
--- /dev/null
+++ b/test/ide/probes/packages/host/Sources/Startup.twin
@@ -0,0 +1,5 @@
+' The project test/ide/packages.test.mjs imports DocProbePkg into.
+Module Startup
+    Public Sub Main()
+    End Sub
+End Module

From f6ac2a2b7d1e74ed1856f901c0d6a5e88ecb2e90 Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 13:28:13 +0200
Subject: [PATCH 08/22] scripts, builder: check_cli's cases move to
 scripts/lib/cli-cases.mjs; pdf.mjs reads the book's fonts from print.css

---
 WIP.Typography.md               |   5 +-
 builder/PLAN-TOOLING-REVIEW.md  |   6 +-
 builder/pdf.mjs                 |  36 +-
 docs/Documentation/Builder.md   |   4 +-
 docs/Documentation/Extending.md |   2 +-
 docs/assets/css/print.css       |   6 +-
 scripts/check_cli.mjs           | 711 +------------------------------
 scripts/lib/cli-cases.mjs       | 726 ++++++++++++++++++++++++++++++++
 8 files changed, 761 insertions(+), 735 deletions(-)
 create mode 100644 scripts/lib/cli-cases.mjs

diff --git a/WIP.Typography.md b/WIP.Typography.md
index 038502a7..c50a550f 100644
--- a/WIP.Typography.md
+++ b/WIP.Typography.md
@@ -65,8 +65,9 @@ once, and any of the three can move.
   the later `@font-face` fetch is not reused, so the file downloads twice.
 - [docs/assets/css/print.css](docs/assets/css/print.css) --- the book's own
   `@font-face` block and three stacks.
-- [builder/pdf.mjs](builder/pdf.mjs) --- `REQUIRED_FONTS`, copied into the
-  sparse `_site-pdf/` tree. Keep it in step with print.css's `@font-face` block.
+- [builder/pdf.mjs](builder/pdf.mjs) --- copies every face print.css names
+  as `url("../fonts/...")` into the sparse `_site-pdf/` tree, reading the
+  list from print.css itself.
 
 Two rules that are easy to get wrong:
 
diff --git a/builder/PLAN-TOOLING-REVIEW.md b/builder/PLAN-TOOLING-REVIEW.md
index be8454cf..b4412fa8 100644
--- a/builder/PLAN-TOOLING-REVIEW.md
+++ b/builder/PLAN-TOOLING-REVIEW.md
@@ -877,7 +877,7 @@ expectations, the usage texts and Tools.md together.
 stdout and exiting 0. Each declares `help` with `short: "h"` and `stopAt: ["help"]`, answers it
 straight after the parse, before any number, project or install check, and has a `USAGE`
 constant (the usage line, one sentence, the options, and the `Exit codes:` block). A new tool
-is added to `HELP_TOOLS` in `scripts/check_cli.mjs`, which checks that its help exits 0 and
+is added to `HELP_TOOLS` in `scripts/lib/cli-cases.mjs`, from which `scripts/check_cli.mjs` checks that its help exits 0 and
 leaves its scratch folder empty.
 
 ### C72 — `scripts, book, eval, wisdom: an unknown flag or a bad value exits 2`
@@ -888,7 +888,7 @@ boolean given a value, a value option with none, an empty value unless the optio
 `empty: true` (only `tbdocs`' `--baseurl`), and a positional beyond the tool's count are each a
 `CliError`, reported on stderr with exit 2 through `withUsageError`. A term that starts with a
 dash goes after `--`. A new tool needs an unknown-flag case in `REFUSALS`, and an empty-value
-case if it has a value option, in `scripts/check_cli.mjs`, which checks `REFUSALS` against
+case if it has a value option, in `scripts/lib/cli-cases.mjs`, which checks `REFUSALS` against
 `HELP_TOOLS`.
 
 ### C72a — `scripts, book, eval, wisdom: a bad value exits 2`
@@ -899,7 +899,7 @@ file, and refuses a bad one on stderr with exit 2, in its usage-error form. It d
 `lib/cli.mjs`'s `numberOption` (read as `Number()` reads, so `0x10` passes and `12abc` does
 not), `choiceOption`, `regexOption`, `urlOption`, `dateOption` and `refuseTogether`, and a
 new option that takes a number, regex, URL, date or fixed set needs a case in `BAD_VALUES` in
-`scripts/check_cli.mjs`.
+`scripts/lib/cli-cases.mjs`.
 
 ### C72b — `builder, scripts: tbdocs and check_links exit 0, 1 or 2 like every tool`
 
diff --git a/builder/pdf.mjs b/builder/pdf.mjs
index ed7dd3cf..98386b9b 100644
--- a/builder/pdf.mjs
+++ b/builder/pdf.mjs
@@ -25,18 +25,13 @@ import { WRITE_LIMIT, mkdirRec, runLimited, safeWrite, writeFileMkdirp } from ".
 const PDF_SUFFIX = "-pdf";
 const REQUIRED_CSS = ["assets/css/print.css", "assets/css/tb-highlight.css"];
 
-// The six faces print.css declares, copied into the sparse tree so its
+// The faces print.css declares, copied into the sparse tree so its
 // `url("../fonts/...")` resolves under the file:// URL render-book.mjs loads.
-// This list has to stay in step with the @font-face block at the top of
-// print.css.
-const REQUIRED_FONTS = [
-  "assets/fonts/source-serif-4-variable.woff2",
-  "assets/fonts/source-serif-4-variable-italic.woff2",
-  "assets/fonts/inter-variable.woff2",
-  "assets/fonts/inter-variable-italic.woff2",
-  "assets/fonts/cascadia-mono-variable.woff2",
-  "assets/fonts/cascadia-mono-variable-italic.woff2",
-];
+// They are read from print.css itself, so a face added to its @font-face
+// block is copied without a second list to keep in step.
+const PRINT_CSS = "assets/css/print.css";
+const FONT_URL = /url\(\s*["']?\.\.\/fonts\/([^"')\s]+)["']?\s*\)/g;
+const CSS_COMMENT = /\/\*[\s\S]*?\*\//g;
 const LIMIT = WRITE_LIMIT;
 
 // ---------------------------------------------------------------------------
@@ -62,11 +57,12 @@ export async function writePdf(
   const staticByDestRel = new Map(staticFiles.map((s) => [s.destRel.replaceAll("\\", "/"), s]));
   const counters = { bookBytes: 0, html: 0, css: 0, fonts: 0, images: 0, missing: 0 };
   const missingPaths = [];
+  const requiredFonts = await printCssFonts(staticByDestRel);
 
   await Promise.all([
     writePdfBook(bookHtml, pdfRoot, counters),
     copyPdfCss(staticByDestRel, highlightCss, pdfRoot, counters),
-    copyPdfFonts(staticByDestRel, pdfRoot, counters),
+    copyPdfFonts(requiredFonts, staticByDestRel, pdfRoot, counters),
     copyPdfImages(imagePaths, staticByDestRel, pdfRoot, counters, missingPaths),
   ]);
 
@@ -86,7 +82,7 @@ export async function writePdf(
     const missing = new Set(missingPaths);
     counters.checkBook = {
       html: bookHtml,
-      rels: ["book.html", ...REQUIRED_CSS, ...REQUIRED_FONTS, ...imagePaths.filter((r) => !missing.has(r))],
+      rels: ["book.html", ...REQUIRED_CSS, ...requiredFonts, ...imagePaths.filter((r) => !missing.has(r))],
     };
   }
   return counters;
@@ -161,6 +157,16 @@ async function copyPdfCss(staticByDestRel, highlightCss, pdfRoot, counters) {
   for (const w of warnings) console.warn(`pdf: ${w}`);
 }
 
+// The tree-relative path of every face print.css points at, in its order.
+// Comments are dropped first: print.css's own header names the url() form.
+// A missing print.css gives none: copyPdfCss already warns about it.
+async function printCssFonts(staticByDestRel) {
+  const sf = staticByDestRel.get(PRINT_CSS);
+  if (!sf) return [];
+  const css = (await fs.readFile(sf.srcPath, "utf8")).replace(CSS_COMMENT, "");
+  return [...new Set(Array.from(css.matchAll(FONT_URL), (m) => `assets/fonts/${m[1]}`))];
+}
+
 // Copy the webfaces print.css declares into <pdfRoot>/assets/fonts/.
 //
 // This throws where copyPdfCss warns and copyPdfImages collects, because a
@@ -171,8 +177,8 @@ async function copyPdfCss(staticByDestRel, highlightCss, pdfRoot, counters) {
 // rejects a face whose fetch errored, but a declared face the layout never
 // exercises is never fetched at all and passes silently. Failing here names
 // the path instead.
-async function copyPdfFonts(staticByDestRel, pdfRoot, counters) {
-  await runLimited(REQUIRED_FONTS, LIMIT, async (rel) => {
+async function copyPdfFonts(requiredFonts, staticByDestRel, pdfRoot, counters) {
+  await runLimited(requiredFonts, LIMIT, async (rel) => {
     const sf = staticByDestRel.get(rel);
     if (!sf) {
       throw new Error(
diff --git a/docs/Documentation/Builder.md b/docs/Documentation/Builder.md
index 8726d3a8..cc584349 100644
--- a/docs/Documentation/Builder.md
+++ b/docs/Documentation/Builder.md
@@ -573,7 +573,7 @@ This follows on from [Project styling](#project-styling). The site uses three fa
 1. **The font files** (all three faces). [`scripts/build_fonts.py`](Tools#build-fonts) downloads each face's pinned release, verifies its SHA-256, subsets it, and writes the `.woff2` files and their licences into `docs/assets/fonts/`. A new face is an entry in its `SOURCES` table --- the release URL, the hash and the licence --- and one entry per file in `FACES`: the file inside the archive, the pinned axes, the Unicode ranges and the output name. Keep the output `.woff2`, which is the only font format the [publish allowlist](Building#what-the-build-refuses-to-publish) accepts.
 2. **The web stylesheet** (Inter and Cascadia Mono). `docs/_sass/custom/_fonts.scss` holds the `@font-face` rules, inside the `emit-font-faces` mixin, and the `$tb-body-font-family` and `$tb-mono-font-family` stacks, which `docs/assets/css/just-the-docs-combined.scss` passes into the theme. `docs/_sass/modules-dark.scss` passes them again for the dark compilation, and `docs/assets/css/just-the-docs-dark.scss` uses the mono stack once more for `pre`, `kbd` and `samp`. All of these read the two variables, so replacing a face inside an existing stack changes nothing in them. A new stack has to be passed in both compilations, or the dark theme keeps the system fonts --- the [specificity trap](#the-specificity-trap) again.
 3. **The preloads** (the two roman web faces). `fontPreloads()` in `builder/template.mjs` preloads `inter-variable.woff2` and `cascadia-mono-variable.woff2` by name, from its `PRELOAD_FONTS` list. It sets `crossorigin`, which a font preload needs even from the same origin: without it the browser downloads the file twice. A preload of a file that does not exist is a broken link on every page, and the build's link check reports it. The link-check fixture under `test/fixtures/check-src/assets/fonts/` holds stub files under the same two names, so renaming either file means renaming its stub too, or [`check_links_diff.mjs`](Tools#check-links-diff) fails on every pull request.
-4. **The book** (all three faces). `docs/assets/css/print.css` is the whole design of the PDF and loads nothing from the Sass build, so it has its own `@font-face` block and its own stacks. `REQUIRED_FONTS` in `builder/pdf.mjs` names the same six files and copies them into the sparse `_site-pdf/` tree. Keep the two in step: the PDF pass aborts on a listed file that does not exist, and a face `print.css` uses that was not copied fails to load, which aborts the book render.
+4. **The book** (all three faces). `docs/assets/css/print.css` is the whole design of the PDF and loads nothing from the Sass build, so it has its own `@font-face` block and its own stacks. `builder/pdf.mjs` reads that block for every file named as `url("../fonts/...")` and copies each into the sparse `_site-pdf/` tree, so there is no second list to keep in step. The PDF pass aborts on a named file that does not exist.
 5. **Diagram exports** (Inter and Cascadia Mono). `FONT_FILES` in `docs/assets/js/svg-inline.js` maps each family name to its weight range and file names, and the Download and Copy buttons embed those files in an exported SVG or PNG. A family it does not list is exported without its face and without a message; a listed file that no longer exists costs one console warning.
 6. **The Gantt chart** (Inter). `builder/gantt.mjs` writes a `<style>` of its own into the chart on the [Build Info](BuildInfo) page, with its own copy of the text stack.
 7. **The diagram sources** (Inter). Every `.dot` source names the face in its `fontname` attributes, and the browser paints the rendered SVG in whatever those name. The new name must be one Graphviz does not recognise. The widths in the next step are written over the table Graphviz falls back to for an unknown name, so a name it does recognise --- one of its built-in PostScript families, such as Helvetica --- is measured from that family's own table instead.
@@ -607,7 +607,7 @@ The build aborts or flips the exit code under a handful of conditions:
 - **Unpublishable file type.** Every non-page under `docs/` is copied into the output verbatim, so `publish-policy.mjs` holds an allowlist of types that may be published and throws on anything else --- in `discover` over the static-file inventory, naming the source path before a byte is written, and again in `dispatch` over each tree's derived inventory, which is the only sweep that sees redirect stubs, vendored theme assets and the generated auxiliaries. Neither is behind `--check`: a build run with checks off is exactly when nothing else is looking. This one aborts rather than setting an exit code, on the opposite reasoning to the link check below --- a broken link leaves a tree worth inspecting, a tree carrying a private key does not. `SOURCE_EXTENSIONS` and `BUILD_EXTENSIONS` are separate sets so the build can emit `sitemap.xml` and `search-data.json` without blessing a stray `docs/secrets.json`; [`scripts/check_publish_policy.mjs`](Tools#check-publish-policy) asserts they stay separate.
 - **Redirect collision.** A `redirect_from:` entry becomes a stub page at that URL, so two ways of claiming one URL are refused in `deriveRedirectStubs()`: an entry pointing at a URL some page already publishes at, and two pages declaring the same entry. Both name the source file on each side --- a stub silently overwriting a real page, or one of two stubs silently winning, would be invisible in the output.
 - **Destination collision.** `assertNoDestinationCollisions()` runs before the write phase and throws if any static file's destination path equals a page's. The static-file copy and the page write run in parallel, so without the check which one survived would depend on I/O ordering.
-- **Missing PDF input.** Phase 8 aborts on three things the book cannot be assembled without: no page (or more than one) carrying `layout: book-combined`, a font listed in `REQUIRED_FONTS` absent from the source tree (naming `scripts/build_fonts.py`), and any image `book.html` references that is not under the source tree. The last is the one that fires in practice, and `--tolerate-missing-images` downgrades only that one to a warning.
+- **Missing PDF input.** Phase 8 aborts on three things the book cannot be assembled without: no page (or more than one) carrying `layout: book-combined`, a font `print.css` names absent from the source tree (naming `scripts/build_fonts.py`), and any image `book.html` references that is not under the source tree. The last is the one that fires in practice, and `--tolerate-missing-images` downgrades only that one to a warning.
 - **A page the book manifest does not mention.** Not a failure: the book is complete for the manifest it was given. `bookCoverage()` compares every page with `_book.yml`'s entries and its `left_out:` list, and the summary prints a `book:` warning for a page in neither, a page in both, an entry that matches no page, and a landing or foreword URL that names no page. It runs only when the book is built, and [`check_book_coverage.mjs`](Tools#check-book-coverage) holds each finding to a probe. See [Book Configuration](Book-Configuration#pages-left-out-of-the-book).
 - **Worker crash.** A worker handler that throws posts `{ taskFailed, message, stack }` to main; the scheduler calls `_abort()`, the build rejects, and the orchestrator reports the error with the task name in the message.
 - **A worker that never returns at all.** The one failure with no error to report: a handler stuck in an unbounded loop, an exponentially backtracking regex or a promise that never settles posts nothing, so its successors' dependency counts never fall, `_remaining` never reaches zero, and the scheduler's promise never settles. Nothing in the SAB protocol can see it --- the scheduler is waiting on a message that is not coming. `Scheduler` therefore runs a `setInterval` watchdog: if no task completes for `--stall-timeout` seconds (default 120, `0` disables), it aborts with `{ stalled: true }` and prints the outstanding tasks split three ways --- claimed by a worker that never returned (the cause), runnable but unclaimed (including an `F_PIN_TO_PRED` task whose lane is the wedged one), and blocked on a predecessor (the consequence). A `render:` or `flush:` chunk additionally prints its source pages, through an optional `describe()` on the task def that nothing else reads. `Worker.terminate()` does end a thread spinning inside a regex, so the abort really ends the process. Under `--serve` the pool outlives a rebuild, so `serve.mjs` replaces the whole pool when it sees the `stalled` flag rather than identifying the wedged lane --- the SAB records the lane a task *completed* on, not the one that claimed it. See [when a build stops instead of failing](Building#when-a-build-stops) for the reader-facing form.
diff --git a/docs/Documentation/Extending.md b/docs/Documentation/Extending.md
index 3fba4b1e..253d3d66 100644
--- a/docs/Documentation/Extending.md
+++ b/docs/Documentation/Extending.md
@@ -657,7 +657,7 @@ The split exists so that an edit confined to `docs/` usually has to pay for `che
 - **Stop with `die(code, message)`** when the tool cannot go on: it prints the message to standard error and exits with the code. A tool that has something to put back first, as `sweep_attributes.mjs` has the registry, defines its own.
 - **End the usage text with an `Exit codes:` block,** one `  <code>  <meaning>` line per code, a long meaning wrapped under itself.
 
-[`scripts/check_cli.mjs`](Tools#check-cli) holds every tool to this. A new tool is added to its `HELP_TOOLS` list, which makes the tool answer `--help` and `-h` with exit 0 and end its usage with exactly one `Exit codes:` table, and to its `REFUSALS` list, which gives it a case for an unknown flag and for an empty value; the script throws on start if the two lists disagree. A tool that checks a value after the parse gets a case of its own in the script's bad-value list.
+[`scripts/check_cli.mjs`](Tools#check-cli) holds every tool to this, and its cases are in `scripts/lib/cli-cases.mjs`. A new tool is added to that file's `HELP_TOOLS` list, which makes the tool answer `--help` and `-h` with exit 0 and end its usage with exactly one `Exit codes:` table, and to its `REFUSALS` list, which gives it a case for an unknown flag and for an empty value; the gate throws on start if the two lists disagree. A tool that checks a value after the parse gets a case of its own in the same file's bad-value list.
 
 **Exit codes.** Three values, and a new gate in either wrapper uses them this way:
 
diff --git a/docs/assets/css/print.css b/docs/assets/css/print.css
index bb72f991..67012624 100644
--- a/docs/assets/css/print.css
+++ b/docs/assets/css/print.css
@@ -24,9 +24,9 @@
    ("unloaded") as normal. It does still abort if a face is mid-flight or
    errored when the page-breaking pass starts; see its loadFonts() patch.
 
-   What is NOT fine is declaring a face that builder/pdf.mjs does not copy
-   into the sparse _site-pdf/ tree: keep this block and its REQUIRED_FONTS
-   list in step. */
+   builder/pdf.mjs copies into the sparse _site-pdf/ tree every file this
+   block names as url("../fonts/..."), and fails the build on one that is
+   not under docs/assets/fonts/. There is no second list to keep in step. */
 
 @font-face {
   font-family: "Source Serif 4";
diff --git a/scripts/check_cli.mjs b/scripts/check_cli.mjs
index 66ec1fc1..ab422bc3 100644
--- a/scripts/check_cli.mjs
+++ b/scripts/check_cli.mjs
@@ -54,6 +54,7 @@ import {
   withUsageError,
 } from "../lib/cli.mjs";
 import { REPO_ROOT } from "../lib/repo-paths.mjs";
+import { CASES, LEAVES_EMPTY } from "./lib/cli-cases.mjs";
 import { createProbes } from "./lib/gate-probes.mjs";
 
 exitOnCrash();
@@ -718,364 +719,7 @@ function capture(fn) {
 
 // ------------------------------------------------------------ the recorded cases
 
-// biome-ignore format: a table, one entry per line
-const CASES = [
-  // A command-line error in tbdocs and check_links exits 2, as in every tool,
-  // and never reads as a finding, which exits 1. A value flag has no
-  // value at the end of the list or before another flag, and --port is a whole
-  // number from 1 to 65535. check_links prints its errors on stderr, after
-  // "error: ".
-  { tool: "builder/tbdocs.mjs", args: ["--port"], exit: 2, stderr: "--port needs a value\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--dest", "--no-pdf"], exit: 2, stderr: "--dest needs a value\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--port=0"], exit: 2, stderr: "--port expects a whole number from 1 to 65535, got: 0\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "scripts/check_links.mjs", args: ["no-such-tree", "--root-dir"], exit: 2, stderr: "error: --root-dir needs a value\n" },
-  { tool: "scripts/check_links.mjs", args: ["no-such-tree", "--forbid"], exit: 2, stderr: "error: --forbid needs a value\n" },
-
-  // In the four harness tools that check, a value flag with no value, at the end or before another flag,
-  // exits 2. tbbuild follows the message with its usage line.
-  { tool: "scripts/tbbuild.mjs", args: ["--port"], exit: 2, stderr: /^--port needs a value\nusage: node scripts\/tbbuild\.mjs / },
-  { tool: "scripts/tbbuild.mjs", args: ["--timeout", "--keep"], exit: 2, stderr: /^--timeout needs a value\nusage: node scripts\/tbbuild\.mjs / },
-  { tool: "scripts/check_examples.mjs", args: ["--jobs"], exit: 2, stderr: "check_examples: --jobs needs a value\n" },
-  { tool: "scripts/check_examples.mjs", args: ["--port", "--json"], exit: 2, stderr: "check_examples: --port needs a value\n" },
-  { tool: "scripts/census_attributes.mjs", args: ["--out"], exit: 2, stderr: "--out needs a value\n" },
-  { tool: "scripts/census_attributes.mjs", args: ["--exported", "--json"], exit: 2, stderr: "--exported needs a value\n" },
-  { tool: "scripts/census_attributes.mjs", args: ["--src", "x"], exit: 2, stderr: "unknown option: --src\n" },
-  { tool: "scripts/build_package_api.mjs", args: ["--out"], exit: 2, stderr: "--out needs a value\n" },
-  { tool: "scripts/build_package_api.mjs", args: ["--exported", "--check"], exit: 2, stderr: "--exported needs a value\n" },
-  { tool: "scripts/build_package_api.mjs", args: ["--src", "x"], exit: 2, stderr: "unknown option: --src\n" },
-
-  // The a11y and diagram tools. A value flag given
-  // nothing, at the end or as "", or followed by another flag, is refused.
-  // Each of them answers --help on stdout with exit 0.
-  // --theme and --viewport are checked against their lists.
-  // check_dot_fit and build_dot_metrics take one flag of their own besides
-  // --help and -h, and neither has a case beyond those and the generated ones.
-  { tool: "scripts/check_a11y.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/check_a11y\.mjs / },
-  { tool: "scripts/check_a11y.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "scripts/check_a11y.mjs", args: ["--root-dir"], exit: 2, stderr: "--root-dir needs a value\n" },
-  { tool: "scripts/check_a11y.mjs", args: ["--root-dir", "--theme", "dark"], exit: 2, stderr: "--root-dir needs a value\n" },
-  { tool: "scripts/check_a11y.mjs", args: ["--theme", ""], exit: 2, stderr: "--theme needs a non-empty value\n" },
-  { tool: "scripts/check_a11y.mjs", args: ["--theme", "drak"], exit: 2, stderr: 'unknown --theme "drak"; expected one of light, dark or both\n' },
-  { tool: "scripts/check_a11y.mjs", args: ["--viewport", "huge"], exit: 2, stderr: 'unknown --viewport "huge"; expected one of desktop, mobile or both\n' },
-  { tool: "scripts/check_a11y_fingerprint.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/check_a11y_fingerprint\.mjs / },
-  { tool: "scripts/check_a11y_fingerprint.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "scripts/check_a11y_fingerprint.mjs", args: ["--pages"], exit: 2, stderr: "--pages needs a value\n" },
-  { tool: "scripts/check_a11y_fingerprint.mjs", args: ["--out"], exit: 2, stderr: "--out needs a value\n" },
-  { tool: "scripts/check_a11y_fingerprint.mjs", args: ["--json", "x"], exit: 2, stderr: "unknown option: --json\n" },
-  { tool: "scripts/check_a11y_fingerprint.mjs", args: ["--theme", "drak"], exit: 2, stderr: 'unknown --theme "drak"; expected one of light, dark or both\n' },
-  { tool: "scripts/check_axe_patch_equiv.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/check_axe_patch_equiv\.mjs / },
-  { tool: "scripts/check_axe_patch_equiv.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "scripts/check_axe_patch_equiv.mjs", args: ["--patch"], exit: 2, stderr: "--patch needs a value\n" },
-  { tool: "scripts/check_pdf_shims_equiv.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/check_pdf_shims_equiv\.mjs\n/ },
-  { tool: "scripts/check_pdf_shims_equiv.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "scripts/check_impexp_parity.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/check_impexp_parity\.mjs\n/ },
-  { tool: "scripts/check_impexp_parity.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "scripts/check_tree_fresh.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/check_tree_fresh\.mjs / },
-  { tool: "scripts/check_tree_fresh.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "scripts/check_tree_fresh.mjs", args: ["--source"], exit: 2, stderr: "--source needs a value\n" },
-  { tool: "scripts/check_tree_fresh.mjs", args: ["--tree"], exit: 2, stderr: "--tree needs a value\n" },
-  { tool: "scripts/pick_a11y_sample.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/pick_a11y_sample\.mjs / },
-  { tool: "scripts/pick_a11y_sample.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "scripts/pick_a11y_sample.mjs", args: ["--budget"], exit: 2, stderr: "--budget needs a value\n" },
-  { tool: "scripts/sweep_a11y.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/sweep_a11y\.mjs / },
-  { tool: "scripts/sweep_a11y.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "scripts/sweep_a11y.mjs", args: ["--limit"], exit: 2, stderr: "--limit needs a value\n" },
-  { tool: "scripts/sweep_a11y.mjs", args: ["--theme", "drak"], exit: 2, stderr: 'unknown --theme "drak"; expected one of light, dark or both\n' },
-  { tool: "scripts/sweep_a11y.mjs", args: ["--viewport", "huge"], exit: 2, stderr: 'unknown --viewport "huge"; expected one of desktop, mobile or both\n' },
-
-  // The harness tools. All of them answer --help and -h
-  // on stdout with exit 0 before any other check, a number or a missing
-  // project included. tbbuild finds its project anywhere in the list.
-  // An unknown option, a value flag with no value or an empty one is
-  // refused, and tbbuild and tbrun follow the message with their usage.
-  // gen_attribute_probes takes one output folder and an optional key file, so
-  // only its empty list is a case here.
-  { tool: "scripts/tbbuild.mjs", args: [], exit: 2, stderr: /^usage: node scripts\/tbbuild\.mjs / },
-  { tool: "scripts/tbbuild.mjs", args: ["x.twinproj", "--help"], exit: 0, stdout: /^usage: node scripts\/tbbuild\.mjs / },
-  { tool: "scripts/tbbuild.mjs", args: ["x.twinproj", "--arch", "win99"], exit: 2, stderr: /^--arch expects win32 or win64, got: win99\nusage: node scripts\/tbbuild\.mjs / },
-  { tool: "scripts/tbbuild.mjs", args: ["x.twinproj", "--port", "1.5"], exit: 2, stderr: /^--port expects a whole number from 1 to 65535, got: 1\.5\nusage: node scripts\/tbbuild\.mjs / },
-  { tool: "scripts/tbbuild.mjs", args: ["x.twinproj", "--timeout", "abc"], exit: 2, stderr: /^--timeout expects a number greater than 0, got: abc\nusage: node scripts\/tbbuild\.mjs / },
-  { tool: "scripts/tbbuild.mjs", args: ["x.twinproj", "--timeout", "-3"], exit: 2, stderr: /^--timeout needs a value\nusage: node scripts\/tbbuild\.mjs / },
-  { tool: "scripts/tbbuild.mjs", args: ["x.twinproj", "--port", "0", "--help"], exit: 0, stdout: /^usage: node scripts\/tbbuild\.mjs / },
-  { tool: "scripts/tbbuild.mjs", args: ["--bogus", "--keep", "x.twinproj"], exit: 2, stderr: /^unknown option: --bogus\nusage: node scripts\/tbbuild\.mjs / },
-  { tool: "scripts/tbbuild.mjs", args: ["--keep", "x.twinproj"], exit: 2, stderr: "no such project: x.twinproj\n" },
-  { tool: "scripts/tbrun.mjs", args: [], exit: 2, stderr: /^usage: node scripts\/tbrun\.mjs / },
-  { tool: "scripts/tbrun.mjs", args: ["no-such-dir", "--help"], exit: 0, stdout: /^usage: node scripts\/tbrun\.mjs / },
-  { tool: "scripts/tbrun.mjs", args: ["no-such-dir", "--arch", "win99"], exit: 2, stderr: /^--arch expects win32 or win64, got: win99\nusage: node scripts\/tbrun\.mjs / },
-  { tool: "scripts/tbrun.mjs", args: ["--port", "no-such-dir"], exit: 2, stderr: /^--port expects a whole number from 1 to 65535, got: no-such-dir\nusage: node scripts\/tbrun\.mjs / },
-  { tool: "scripts/tbrun.mjs", args: ["no-such-dir", "--arch"], exit: 2, stderr: /^--arch needs a value\nusage: node scripts\/tbrun\.mjs / },
-  { tool: "scripts/tbrun.mjs", args: ["no-such-dir", "--arch", ""], exit: 2, stderr: /^--arch needs a non-empty value\nusage: node scripts\/tbrun\.mjs / },
-  { tool: "scripts/tbrun.mjs", args: ["--bogus", "no-such-dir"], exit: 2, stderr: /^unknown option: --bogus\nusage: node scripts\/tbrun\.mjs / },
-  { tool: "scripts/tbrun.mjs", args: ["no-such-dir", "--arch", "win64"], exit: 2, stderr: /^not a directory: .*no-such-dir\ntbrun takes an exported source tree / },
-  { tool: "scripts/addin_test.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/addin_test\.mjs / },
-  { tool: "scripts/addin_test.mjs", args: ["--ide"], exit: 2, stderr: "--ide needs a value\n" },
-  { tool: "scripts/addin_test.mjs", args: ["--ide", ""], exit: 2, stderr: "--ide needs a non-empty value\n" },
-  { tool: "scripts/addin_test.mjs", args: ["--ide", "no-such.exe"], exit: 2, stderr: /^no twinBASIC IDE found: pass --ide / },
-  { tool: "scripts/ide_test.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/ide_test\.mjs / },
-  { tool: "scripts/ide_test.mjs", args: ["--ide"], exit: 2, stderr: "--ide needs a value\n" },
-  { tool: "scripts/ide_test.mjs", args: ["--ide", ""], exit: 2, stderr: "--ide needs a non-empty value\n" },
-  { tool: "scripts/ide_test.mjs", args: ["--ide", "no-such.exe"], exit: 2, stderr: /^no twinBASIC IDE found: pass --ide / },
-  { tool: "scripts/check_examples.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/check_examples\.mjs \[options\]\n/ },
-  { tool: "scripts/check_examples.mjs", args: ["--jobs", "0"], exit: 2, stderr: "check_examples: --jobs expects a whole number of at least 1, got: 0\n" },
-  { tool: "scripts/check_examples.mjs", args: ["--batch", "1.5"], exit: 2, stderr: "check_examples: --batch expects a whole number of at least 1, got: 1.5\n" },
-  { tool: "scripts/check_examples.mjs", args: ["--jobs", "0", "--help"], exit: 0, stdout: /^usage: node scripts\/check_examples\.mjs \[options\]\n/ },
-  { tool: "scripts/check_examples.mjs", args: ["--help", "--jobs"], exit: 0, stdout: /^usage: node scripts\/check_examples\.mjs \[options\]\n/ },
-  { tool: "scripts/census_attributes.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/census_attributes\.mjs \[options\]\n/ },
-  { tool: "scripts/census_attributes.mjs", args: ["--help", "--attr"], exit: 0, stdout: /^usage: node scripts\/census_attributes\.mjs \[options\]\n/ },
-  { tool: "scripts/census_attributes.mjs", args: ["--dump-sites"], exit: 2, stderr: "--dump-sites needs a value\n" },
-  { tool: "scripts/build_package_api.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/build_package_api\.mjs \[options\]\n/ },
-  { tool: "scripts/gen_attribute_probes.mjs", args: [], exit: 2, stderr: /^Generate a twinBASIC probe project for Reference\/Attributes\.md applicability\.\n/ },
-
-  // The gates and link tools. check_links prints its
-  // errors on stderr, after "error: ", and exits 2. Every one of them refuses
-  // an unknown option, a stray argument, a value given to a flag that takes
-  // none, and a value flag with no value, and crawl_check, compare_trees and
-  // survey_tooling follow the message with their usage. check_lint prints its
-  // name, the message and its usage line. check_regex_safety,
-  // check_code_regions, check_gate_lists and convert_em_dash_separators take
-  // only flags of their own, and none has a case beyond --help, -h and the
-  // generated ones below.
-  { tool: "scripts/check_links.mjs", args: ["--help"], exit: 0, stdout: /^Usage: node check_links\.mjs \[options\] <inputs\.\.\.>\n/ },
-  { tool: "scripts/check_links.mjs", args: ["no-such-tree"], exit: 2, stderr: "error: --offline is required. Online (network) checking is not implemented by this tool.\n" },
-  { tool: "scripts/check_links.mjs", args: ["--offline"], exit: 2, stderr: "error: at least one input file or directory is required\n" },
-  { tool: "scripts/check_links.mjs", args: ["--offline", "--bogus", "no-such-tree"], exit: 2, stderr: "error: unknown option: --bogus\n" },
-  { tool: "scripts/check_links.mjs", args: ["--offline", "-x", "--bogus=1"], exit: 2, stderr: "error: unknown option: -x\n" },
-  { tool: "scripts/check_links.mjs", args: ["--offline", "--root-dir", "--forbid"], exit: 2, stderr: "error: --root-dir needs a value\n" },
-  { tool: "scripts/check_links_diff.mjs", args: ["--help"], exit: 0, stdout: /^Usage: node scripts\/check_links_diff\.mjs \[options\]\n/ },
-  { tool: "scripts/check_links_diff.mjs", args: [], exit: 2, stderr: /^error: --a and --b are both 'script', which compares nothing\.\n/ },
-  { tool: "scripts/check_links_diff.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "scripts/check_links_diff.mjs", args: ["stray"], exit: 2, stderr: "unexpected argument: stray\n" },
-  { tool: "scripts/check_links_diff.mjs", args: ["--list=1"], exit: 2, stderr: "--list takes no value\n" },
-  { tool: "scripts/crawl_check.mjs", args: [], exit: 2, stderr: /^usage: node scripts\/crawl_check\.mjs <start-url> / },
-  { tool: "scripts/crawl_check.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/crawl_check\.mjs <start-url> / },
-  { tool: "scripts/crawl_check.mjs", args: ["--bogus", "http://127.0.0.1:9/"], exit: 2, stderr: /^unknown option: --bogus\nusage: node scripts\/crawl_check\.mjs <start-url> / },
-  { tool: "scripts/crawl_check.mjs", args: ["--timeout", "5", "-x"], exit: 2, stderr: /^unknown option: -x\nusage: node scripts\/crawl_check\.mjs <start-url> / },
-  { tool: "scripts/crawl_check.mjs", args: ["--skip-external=1"], exit: 2, stderr: /^--skip-external takes no value\nusage: node scripts\/crawl_check\.mjs <start-url> / },
-  { tool: "scripts/crawl_check.mjs", args: ["--concurrency", "--bogus"], exit: 2, stderr: /^--concurrency needs a value\nusage: node scripts\/crawl_check\.mjs <start-url> / },
-  { tool: "scripts/check_publish_policy.mjs", args: ["--src"], exit: 2, stderr: "--src needs a value\n" },
-  { tool: "scripts/survey_tooling.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/survey_tooling\.mjs \[--root DIR\] / },
-  { tool: "scripts/survey_tooling.mjs", args: ["--bogus"], exit: 2, stderr: /^unknown option: --bogus\nusage: node scripts\/survey_tooling\.mjs \[--root DIR\] / },
-  { tool: "scripts/survey_tooling.mjs", args: ["stray"], exit: 2, stderr: /^unexpected argument: stray\nusage: node scripts\/survey_tooling\.mjs \[--root DIR\] / },
-  { tool: "scripts/survey_tooling.mjs", args: ["--root"], exit: 2, stderr: /^--root needs a value\nusage: node scripts\/survey_tooling\.mjs \[--root DIR\] / },
-  { tool: "scripts/survey_tooling.mjs", args: ["--window", "0"], exit: 2, stderr: /^--window expects a whole number of at least 1, got: 0\nusage: node scripts\/survey_tooling\.mjs / },
-  { tool: "scripts/survey_tooling.mjs", args: ["--top", "1.5"], exit: 2, stderr: /^--top expects a whole number of at least 1, got: 1\.5\nusage: node scripts\/survey_tooling\.mjs / },
-  { tool: "scripts/survey_tooling.mjs", args: ["--window", "0", "--help"], exit: 0, stdout: /^usage: node scripts\/survey_tooling\.mjs \[--root DIR\] / },
-  { tool: "scripts/check_lint.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/check_lint\.mjs \[--staged\]\n/ },
-  { tool: "scripts/check_lint.mjs", args: ["--staged", "--staged"], exit: 2, stderr: "check_lint: --staged given more than once\nusage: node scripts/check_lint.mjs [--staged]\n" },
-  { tool: "scripts/check_lint.mjs", args: ["--staged", "x"], exit: 2, stderr: "check_lint: unexpected argument: x\nusage: node scripts/check_lint.mjs [--staged]\n" },
-  { tool: "scripts/check_lint.mjs", args: ["--"], exit: 2, stderr: "check_lint: unexpected argument: --\nusage: node scripts/check_lint.mjs [--staged]\n" },
-  { tool: "scripts/check_lint.mjs", args: ["--staged=1"], exit: 2, stderr: "check_lint: --staged takes no value\nusage: node scripts/check_lint.mjs [--staged]\n" },
-  { tool: "scripts/check_lint.mjs", args: ["--bogus"], exit: 2, stderr: "check_lint: unknown option: --bogus\nusage: node scripts/check_lint.mjs [--staged]\n" },
-  { tool: "scripts/compare_trees.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/compare_trees\.mjs \[--before <ref>\] / },
-  { tool: "scripts/compare_trees.mjs", args: ["--bogus"], exit: 2, stderr: /^compare_trees: unknown option: --bogus\n\nusage: node scripts\/compare_trees\.mjs / },
-  { tool: "scripts/compare_trees.mjs", args: ["stray"], exit: 2, stderr: /^compare_trees: unexpected argument: stray\n\nusage: node scripts\/compare_trees\.mjs / },
-  { tool: "scripts/compare_trees.mjs", args: ["--before"], exit: 2, stderr: /^compare_trees: --before needs a value\n\nusage: node scripts\/compare_trees\.mjs / },
-  { tool: "scripts/compare_trees.mjs", args: ["--max", "--keep"], exit: 2, stderr: /^compare_trees: --max needs a value\n\nusage: node scripts\/compare_trees\.mjs / },
-  { tool: "scripts/compare_trees.mjs", args: ["--max", "1.5"], exit: 2, stderr: /^compare_trees: --max expects a whole number of at least 0, got: 1\.5\n\nusage: node scripts\/compare_trees\.mjs / },
-  { tool: "scripts/compare_trees.mjs", args: ["--bogus", "--help"], exit: 2, stderr: /^compare_trees: unknown option: --bogus\n\nusage: node scripts\/compare_trees\.mjs / },
-  { tool: "scripts/compare_trees.mjs", args: ["--before", "--", "x"], exit: 2, stderr: /^compare_trees: --before needs a value\n\nusage: node scripts\/compare_trees\.mjs / },
-  { tool: "scripts/compare_trees.mjs", args: ["--keep=1"], exit: 2, stderr: /^compare_trees: --keep takes no value\n\nusage: node scripts\/compare_trees\.mjs / },
-
-  // render-book, eval/ and wisdom. In every one of them an
-  // unknown option, a value flag with no value and a value given to a boolean
-  // are refused at the parse, in the parser's own words, exit 2, and so is an
-  // argument beyond those a tool takes (nav_hops and site_search take any
-  // number). A search term or a file name that starts with a dash goes after
-  // --. build_corpus, nav_hops, run_case, site_search and transcript print
-  // their usage on stderr when an argument they need is
-  // missing; wisdom does when no command is given, and names an unknown one.
-  // Every tool here answers -h and --help on stdout with exit 0, and
-  // reads nothing after it. The command in the wisdom cases is never a real
-  // one, so that none can start an export. render-book's missing input file is
-  // not a usage error, but exits 2 as one does, and so does a --site that holds
-  // no search index.
-  { tool: "book/render-book.mjs", args: ["--help"], exit: 0, stdout: /^usage: node render-book\.mjs <input\.html> / },
-  { tool: "book/render-book.mjs", args: [], exit: 2, stderr: "usage: node render-book.mjs <input.html> -o <output.pdf> [--outline-tags ...] [-t ms] [--additional-script path]...\n" },
-  { tool: "book/render-book.mjs", args: ["a.html", "b.html"], exit: 2, stderr: "unexpected argument: b.html\n" },
-  { tool: "book/render-book.mjs", args: ["a.html", "-o"], exit: 2, stderr: "-o needs a value\n" },
-  { tool: "book/render-book.mjs", args: ["-o", "--bogus", "a.html"], exit: 2, stderr: "-o needs a value\n" },
-  { tool: "book/render-book.mjs", args: ["a.html", "-o", "out.pdf", "--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "book/render-book.mjs", args: ["a.html", "-o", "out.pdf", "--outline-tags"], exit: 2, stderr: "--outline-tags needs a value\n" },
-  { tool: "book/render-book.mjs", args: ["a.html", "-o", "out.pdf", "-t", "abc"], exit: 2, stderr: "--timeout expects a whole number from 0 to 2147483647, got: abc\n" },
-  { tool: "book/render-book.mjs", args: ["-x"], exit: 2, stderr: "unknown option: -x\n" },
-  { tool: "eval/build_corpus.mjs", args: ["--help"], exit: 0, stdout: /^Usage: node eval\/build_corpus\.mjs --dest <path> / },
-  { tool: "eval/build_corpus.mjs", args: [], exit: 2, stderr: /^Usage: node eval\/build_corpus\.mjs --dest <path> / },
-  { tool: "eval/build_corpus.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "eval/build_corpus.mjs", args: ["stray"], exit: 2, stderr: "unexpected argument: stray\n" },
-  { tool: "eval/build_corpus.mjs", args: ["--help", "--bogus"], exit: 0, stdout: /^Usage: node eval\/build_corpus\.mjs --dest <path> / },
-  { tool: "eval/build_corpus.mjs", args: ["--quiet=1"], exit: 2, stderr: "--quiet takes no value\n" },
-  { tool: "eval/build_corpus.mjs", args: ["-hq"], exit: 0, stdout: /^Usage: node eval\/build_corpus\.mjs --dest <path> / },
-  { tool: "eval/build_corpus.mjs", args: ["--repo"], exit: 2, stderr: "--repo needs a value\n" },
-  { tool: "eval/build_corpus.mjs", args: ["--src", "x"], exit: 2, stderr: "unknown option: --src\n" },
-  { tool: "eval/nav_hops.mjs", args: ["--help"], exit: 0, stdout: /^Usage: node eval\/nav_hops\.mjs \[--from <page>\] / },
-  { tool: "eval/nav_hops.mjs", args: [], exit: 2, stderr: /^Usage: node eval\/nav_hops\.mjs \[--from <page>\] / },
-  { tool: "eval/nav_hops.mjs", args: ["--from", "nope.md", "x"], exit: 2, stderr: /^no start page: .*[\\/]nope\.md\n$/ },
-  { tool: "eval/nav_hops.mjs", args: ["--repo", "nowhere", "--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "eval/nav_hops.mjs", args: ["--repo", "nowhere", "--", "--bogus"], exit: 2, stderr: /^no start page: .*[\\/]nowhere[\\/]docs[\\/]index\.md\n$/ },
-  { tool: "eval/nav_hops.mjs", args: ["--help=1", "--repo", "nowhere"], exit: 2, stderr: "--help takes no value\n" },
-  { tool: "eval/nav_hops.mjs", args: ["--from", "--repo", "x"], exit: 2, stderr: "--from needs a value\n" },
-  { tool: "eval/nav_hops.mjs", args: ["--src", "x", "y"], exit: 2, stderr: "unknown option: --src\n" },
-  { tool: "eval/nav_hops.mjs", args: ["--", "C:/x"], exit: 2, stderr: "these patterns arrived as Windows paths: C:/x\nGit Bash converted them. Run with MSYS_NO_PATHCONV=1 set, or from another shell.\n" },
-  { tool: "eval/nav_hops.mjs", args: ["--repo"], exit: 2, stderr: "--repo needs a value\n" },
-  { tool: "eval/nav_hops.mjs", args: ["x", "--from"], exit: 2, stderr: "--from needs a value\n" },
-  { tool: "eval/run_case.mjs", args: ["--help"], exit: 0, stdout: /^Usage: node eval\/run_case\.mjs --corpus <dir> / },
-  { tool: "eval/run_case.mjs", args: [], exit: 2, stderr: /^Usage: node eval\/run_case\.mjs --corpus <dir> / },
-  { tool: "eval/run_case.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "eval/run_case.mjs", args: ["stray"], exit: 2, stderr: "unexpected argument: stray\n" },
-  { tool: "eval/run_case.mjs", args: ["--help", "--bogus"], exit: 0, stdout: /^Usage: node eval\/run_case\.mjs --corpus <dir> / },
-  { tool: "eval/run_case.mjs", args: ["--prompt-only=1"], exit: 2, stderr: "--prompt-only takes no value\n" },
-  { tool: "eval/run_case.mjs", args: ["--corpus"], exit: 2, stderr: "--corpus needs a value\n" },
-  { tool: "eval/run_case.mjs", args: ["--smoke", "--corpus", "c", "--site", "s", "--out", "o"], exit: 2, stderr: /^missing: .*[\\/]c[\\/]docs, .*search-data\.json, .*lunr\.min\.js\n$/ },
-  { tool: "eval/run_case.mjs", args: ["--smoke", "--corpus", "c", "--site", "s", "--out", "o", "--timeout", "abc"], exit: 2, stderr: "--timeout expects a number greater than 0 and at most 35791, got: abc\n" },
-  { tool: "eval/run_case.mjs", args: ["--corpus", "c", "--site", "s", "--out", "o", "--protocol", "repo"], exit: 2, stderr: /^Usage: node eval\/run_case\.mjs --corpus <dir> / },
-  { tool: "eval/run_case.mjs", args: ["--corpus", "c", "--site", "s", "--out", "o", "--protocol", "--smoke"], exit: 2, stderr: "--protocol needs a value\n" },
-  { tool: "eval/site_search.mjs", args: ["--help"], exit: 0, stdout: /^Usage: node eval\/site_search\.mjs "<query>" / },
-  { tool: "eval/site_search.mjs", args: [], exit: 2, stderr: /^Usage: node eval\/site_search\.mjs "<query>" / },
-  { tool: "eval/site_search.mjs", args: ["--site", "nowhere", "--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "eval/site_search.mjs", args: ["--site", "nowhere", "--", "--bogus"], exit: 2, stderr: /^missing .*search-data\.json\nRun build\.bat / },
-  { tool: "eval/site_search.mjs", args: ["--help=1", "--site", "nowhere"], exit: 2, stderr: "--help takes no value\n" },
-  { tool: "eval/site_search.mjs", args: ["--composition", "--site", "nowhere"], exit: 2, stderr: /^missing .*search-data\.json\nRun build\.bat / },
-  { tool: "eval/site_search.mjs", args: ["--site"], exit: 2, stderr: "--site needs a value\n" },
-  { tool: "eval/search_quality.mjs", args: ["--help"], exit: 0, stdout: /^Usage: node eval\/search_quality\.mjs \[--site docs\/_site\] / },
-  { tool: "eval/search_quality.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "eval/search_quality.mjs", args: ["stray"], exit: 2, stderr: "unexpected argument: stray\n" },
-  { tool: "eval/search_quality.mjs", args: ["--help", "--bogus"], exit: 0, stdout: /^Usage: node eval\/search_quality\.mjs \[--site docs\/_site\] / },
-  { tool: "eval/search_quality.mjs", args: ["--help=1"], exit: 2, stderr: "--help takes no value\n" },
-  { tool: "eval/search_quality.mjs", args: ["-x"], exit: 2, stderr: "unknown option: -x\n" },
-  { tool: "eval/search_quality.mjs", args: ["--site", "nowhere"], exit: 2, stderr: /^missing .*search-data\.json\nRun build\.bat / },
-  { tool: "eval/search_quality.mjs", args: ["--site", "nowhere", "--sample", "abc"], exit: 2, stderr: "--sample expects a whole number of at least 1, got: abc\n" },
-  { tool: "eval/search_quality.mjs", args: ["--site", "--help"], exit: 2, stderr: "--site needs a value\n" },
-  { tool: "eval/search_quality.mjs", args: ["--site"], exit: 2, stderr: "--site needs a value\n" },
-  { tool: "eval/search_quality.mjs", args: ["--site", "nowhere", "--save"], exit: 2, stderr: "--save needs a value\n" },
-  { tool: "eval/transcript.mjs", args: ["--help"], exit: 0, stdout: /^Usage: node eval\/transcript\.mjs <case\.jsonl> / },
-  { tool: "eval/transcript.mjs", args: ["-h"], exit: 0, stdout: /^Usage: node eval\/transcript\.mjs <case\.jsonl> / },
-  { tool: "eval/transcript.mjs", args: [], exit: 2, stderr: /^Usage: node eval\/transcript\.mjs <case\.jsonl> / },
-  { tool: "eval/transcript.mjs", args: ["nope.jsonl", "--help"], exit: 0, stdout: /^Usage: node eval\/transcript\.mjs <case\.jsonl> / },
-  { tool: "eval/transcript.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "eval/transcript.mjs", args: ["--help=1"], exit: 2, stderr: "--help takes no value\n" },
-  { tool: "eval/transcript.mjs", args: ["nope.jsonl"], exit: 2, stderr: /Error: ENOENT: no such file or directory, open '[^']*nope\.jsonl'\r?\n/ },
-  { tool: "eval/transcript.mjs", args: ["--bogus", "nope.jsonl"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "eval/transcript.mjs", args: ["-x"], exit: 2, stderr: "unknown option: -x\n" },
-  { tool: "eval/transcript.mjs", args: ["--", "-x"], exit: 2, stderr: /Error: ENOENT: no such file or directory, open '(?:[^']*[\\/])?-x'\r?\n/ },
-  { tool: "eval/transcript.mjs", args: ["a.jsonl", "b.jsonl"], exit: 2, stderr: "unexpected argument: b.jsonl\n" },
-  { tool: "wisdom/wisdom.mjs", args: [], exit: 2, stderr: /^Usage: node wisdom\/wisdom\.mjs <command> \[options\]\n/ },
-  { tool: "wisdom/wisdom.mjs", args: ["--help"], exit: 0, stdout: /^Usage: node wisdom\/wisdom\.mjs <command> \[options\]\n/ },
-  { tool: "wisdom/wisdom.mjs", args: ["bogus"], exit: 2, stderr: /^unknown command: bogus\nUsage: node wisdom\/wisdom\.mjs <command> \[options\]\n/ },
-  { tool: "wisdom/wisdom.mjs", args: ["bogus", "--guild", "--bogus"], exit: 2, stderr: "--guild needs a value\n" },
-  { tool: "wisdom/wisdom.mjs", args: ["bogus", "--cap"], exit: 2, stderr: "--cap needs a value\n" },
-  { tool: "wisdom/wisdom.mjs", args: ["bogus", "--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "wisdom/wisdom.mjs", args: ["bogus", "stray"], exit: 2, stderr: "unexpected argument: stray\n" },
-  { tool: "wisdom/wisdom.mjs", args: ["bogus", "--help"], exit: 0, stdout: /^Usage: node wisdom\/wisdom\.mjs <command> \[options\]\n/ },
-  { tool: "wisdom/wisdom.mjs", args: ["bogus", "--force=1"], exit: 2, stderr: "--force takes no value\n" },
-  { tool: "wisdom/wisdom.mjs", args: ["bogus", "-x"], exit: 2, stderr: "unknown option: -x\n" },
-  { tool: "wisdom/wisdom.mjs", args: ["bogus", "--guild", "x", "--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-
-  // tbdocs, beyond the cases above. Every command-line
-  // error exits 2. A value flag refuses a missing value and one that starts
-  // with a dash, "--" included; an unknown option is refused as given, as is a
-  // positional, and a boolean given a value. Each --port and --stall-timeout
-  // is checked where it stands, so a bad one fails even when a later one is
-  // good. A --dest the build refuses exits 2 too, after the command line has
-  // been read. --baseurl takes an empty value, meaning the site root; the
-  // other value flags refuse one.
-  { tool: "builder/tbdocs.mjs", args: ["--src"], exit: 2, stderr: "--src needs a value\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--url"], exit: 2, stderr: "--url needs a value\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--check-findings"], exit: 2, stderr: "--check-findings needs a value\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--symbol-gaps", "--serve"], exit: 2, stderr: "--symbol-gaps needs a value\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--dest", "--"], exit: 2, stderr: "--dest needs a value\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--stall-timeout"], exit: 2, stderr: "--stall-timeout needs a value\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--stall-timeout", "-1"], exit: 2, stderr: "--stall-timeout needs a value\n" },
-  { tool: "builder/tbdocs.mjs", args: ["foo"], exit: 2, stderr: "unexpected argument: foo\n" },
-  { tool: "builder/tbdocs.mjs", args: ["-"], exit: 2, stderr: "unexpected argument: -\n" },
-  { tool: "builder/tbdocs.mjs", args: ["-x"], exit: 2, stderr: "unknown option: -x\n" },
-  { tool: "builder/tbdocs.mjs", args: ["-xy"], exit: 2, stderr: "unknown option: -xy\n" },
-  { tool: "builder/tbdocs.mjs", args: ["-h"], exit: 0, stdout: /^usage: node builder\/tbdocs\.mjs \[options\]\n/ },
-  { tool: "builder/tbdocs.mjs", args: ["--help"], exit: 0, stdout: /^usage: node builder\/tbdocs\.mjs \[options\]\n/ },
-  { tool: "builder/tbdocs.mjs", args: ["--dry-run=1"], exit: 2, stderr: "--dry-run takes no value\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--no-check=1"], exit: 2, stderr: "--no-check takes no value\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--no-check", "--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--port", "abc"], exit: 2, stderr: "--port expects a whole number from 1 to 65535, got: abc\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--port="], exit: 2, stderr: "--port needs a non-empty value\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--stall-timeout="], exit: 2, stderr: "--stall-timeout needs a non-empty value\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--port=65536"], exit: 2, stderr: "--port expects a whole number from 1 to 65535, got: 65536\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--port=1.5"], exit: 2, stderr: "--port expects a whole number from 1 to 65535, got: 1.5\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--port=80", "--port=0"], exit: 2, stderr: "--port expects a whole number from 1 to 65535, got: 0\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--port=abc", "--port=80"], exit: 2, stderr: "--port expects a whole number from 1 to 65535, got: abc\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--stall-timeout=-1"], exit: 2, stderr: "--stall-timeout expects a number of at least 0, got: -1\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--stall-timeout=abc"], exit: 2, stderr: "--stall-timeout expects a number of at least 0, got: abc\n" },
-  { tool: "builder/tbdocs.mjs", args: ["--src", ".", "--dest", "."], exit: 2,
-    stderr: /^refusing --dest (.+): it is or contains the source tree \1, which cleaning it would delete\n$/ },
-  { tool: "builder/tbdocs.mjs", args: ["--src=.", "--dest=sub"], exit: 2,
-    stderr: /^refusing --dest (.+)[\\/]sub: it is inside the source tree, so a build would read its output back as source, or serve would rebuild on its own writes\. Use a folder directly under \1 whose name starts with _site, _serve, _pdf, or one inside such a folder, or one outside \1\.\n$/ },
-];
-
-// Every tool prints its usage on stdout and exits 0 for
-// --help and for -h, so each is a case, the two forms alike, unless the table
-// above already holds it. The value is the start of the tool's text where that
-// is not `usage: node <tool>`: an older text that opens otherwise, or one that
-// names the tool without its folder.
-// biome-ignore format: a table, one entry per line
-const HELP_TOOLS = {
-  "builder/tbdocs.mjs": null,
-  "book/render-book.mjs": "usage: node render-book.mjs <input.html> ",
-  "wisdom/wisdom.mjs": "Usage: node wisdom/wisdom.mjs <command> [options]\n",
-  "eval/build_corpus.mjs": "Usage: node eval/build_corpus.mjs ",
-  "eval/nav_hops.mjs": "Usage: node eval/nav_hops.mjs ",
-  "eval/run_case.mjs": "Usage: node eval/run_case.mjs ",
-  "eval/search_quality.mjs": "Usage: node eval/search_quality.mjs ",
-  "eval/site_search.mjs": "Usage: node eval/site_search.mjs ",
-  "eval/transcript.mjs": "Usage: node eval/transcript.mjs ",
-  "scripts/addin_test.mjs": null,
-  "scripts/ide_test.mjs": null,
-  "scripts/build_dot_metrics.mjs": null,
-  "scripts/build_package_api.mjs": null,
-  "scripts/census_attributes.mjs": null,
-  "scripts/check_a11y.mjs": null,
-  "scripts/check_a11y_fingerprint.mjs": null,
-  "scripts/check_axe_patch_equiv.mjs": null,
-  "scripts/check_attribute_sweep.mjs": null,
-  "scripts/check_book_coverage.mjs": null,
-  "scripts/check_ci_workflows.mjs": null,
-  "scripts/check_cli.mjs": null,
-  "scripts/check_code_regions.mjs": null,
-  "scripts/check_dot_fit.mjs": null,
-  "scripts/check_examples.mjs": null,
-  "scripts/check_gate_lists.mjs": null,
-  "scripts/check_impexp_parity.mjs": null,
-  "scripts/check_links.mjs": "Usage: node check_links.mjs [options] <inputs...>\n",
-  "scripts/check_links_diff.mjs": "Usage: node scripts/check_links_diff.mjs [options]\n",
-  "scripts/check_lint.mjs": null,
-  "scripts/check_page_baseline.mjs": null,
-  "scripts/check_pdf_shims_equiv.mjs": null,
-  "scripts/check_publish_policy.mjs": null,
-  "scripts/check_regex_safety.mjs": null,
-  "scripts/check_symbol_index.mjs": null,
-  "scripts/check_tb_registry.mjs": null,
-  "scripts/check_tree_fresh.mjs": null,
-  "scripts/check_twin_parsers.mjs": null,
-  "scripts/compare_trees.mjs": null,
-  "scripts/convert_em_dash_separators.mjs": null,
-  "scripts/crawl_check.mjs": null,
-  "scripts/gen_attribute_probes.mjs": "Generate a twinBASIC probe project for Reference/Attributes.md applicability.\n",
-  "scripts/impexp.mjs": "Usage:\n",
-  "scripts/pick_a11y_sample.mjs": null,
-  "scripts/survey_tooling.mjs": null,
-  "scripts/sweep_a11y.mjs": null,
-  "scripts/sweep_attributes.mjs": null,
-  "scripts/tbbuild.mjs": null,
-  "scripts/tbrun.mjs": null,
-};
-const literal = (text) => text.replace(/[.*+?^${}()|[\]\\/]/g, "\\$&");
-for (const [tool, start] of Object.entries(HELP_TOOLS)) {
-  const opening = start ? literal(start) : `${literal(`usage: node ${tool}`)}[ \\n]`;
-  for (const flag of ["--help", "-h"]) {
-    if (CASES.some((c) => c.tool === tool && c.args.length === 1 && c.args[0] === flag)) continue;
-    CASES.push({ tool, args: [flag], exit: 0, stdout: new RegExp(`^${opening}`) });
-  }
-  if (tool === "scripts/impexp.mjs") continue;
-  CASES.find((c) => c.tool === tool && c.args.length === 1 && c.args[0] === "--help").exitCodes = true;
-}
+// The cases themselves are in scripts/lib/cli-cases.mjs.
 
 // Every usage text ends with its tool's one table of exit codes: a line
 // `Exit codes:`, then a line for each code, `  <code>  <meaning>`, a long
@@ -1084,357 +728,6 @@ for (const [tool, start] of Object.entries(HELP_TOOLS)) {
 const EXIT_TABLE = /\nExit codes:\n(?: {2}\d {2}[^\n]*\n| {5}[^\n]*\n)+$/;
 const oneExitTable = (text) => EXIT_TABLE.test(text) && text.split("Exit codes:").length === 2;
 
-// Every tool refuses an unknown flag and an empty value at
-// the parse, so each has a case for the first and, where it has a value
-// option, for the second: `tool: [option, extras]`, the option given as
-// `--option=`. Both exit 2, print the refusal on
-// stderr and nothing on stdout. `prefix` is the text a tool puts before its
-// message. `args` replaces `--bogus` where the tool must never get further than
-// the parse: convert_em_dash_separators would rewrite docs/ but for --check, and
-// wisdom needs a command that is not a real one. A case the table above already
-// holds, the same tool with the same arguments, is not added again.
-// biome-ignore format: a table, one entry per line
-const REFUSALS = {
-  "builder/tbdocs.mjs": ["src"],
-  "book/render-book.mjs": ["output"],
-  "wisdom/wisdom.mjs": ["guild", { args: ["bogus", "--bogus"], empty: ["bogus", "--guild="] }],
-  "eval/build_corpus.mjs": ["dest"],
-  "eval/nav_hops.mjs": ["from"],
-  "eval/run_case.mjs": ["corpus"],
-  "eval/search_quality.mjs": ["site"],
-  "eval/site_search.mjs": ["site"],
-  "eval/transcript.mjs": [null],
-  "scripts/addin_test.mjs": ["ide"],
-  "scripts/ide_test.mjs": ["ide"],
-  "scripts/build_dot_metrics.mjs": [null],
-  "scripts/build_package_api.mjs": ["out"],
-  "scripts/census_attributes.mjs": ["out"],
-  "scripts/check_a11y.mjs": ["root-dir"],
-  "scripts/check_a11y_fingerprint.mjs": ["pages"],
-  "scripts/check_axe_patch_equiv.mjs": ["patch"],
-  "scripts/check_attribute_sweep.mjs": [null],
-  "scripts/check_book_coverage.mjs": [null],
-  "scripts/check_ci_workflows.mjs": [null],
-  "scripts/check_cli.mjs": [null],
-  "scripts/check_code_regions.mjs": [null],
-  "scripts/check_dot_fit.mjs": [null],
-  "scripts/check_examples.mjs": ["only", { prefix: "check_examples: " }],
-  "scripts/check_gate_lists.mjs": [null],
-  "scripts/check_impexp_parity.mjs": [null],
-  "scripts/check_links.mjs": ["root-dir", { prefix: "error: " }],
-  "scripts/check_links_diff.mjs": ["a"],
-  "scripts/check_lint.mjs": [null, { prefix: "check_lint: " }],
-  "scripts/check_page_baseline.mjs": [null],
-  "scripts/check_pdf_shims_equiv.mjs": [null],
-  "scripts/check_publish_policy.mjs": ["src"],
-  "scripts/check_regex_safety.mjs": [null],
-  "scripts/check_symbol_index.mjs": [null],
-  "scripts/check_tb_registry.mjs": [null],
-  "scripts/check_tree_fresh.mjs": ["tree"],
-  "scripts/check_twin_parsers.mjs": [null],
-  "scripts/compare_trees.mjs": ["before", { prefix: "compare_trees: " }],
-  "scripts/convert_em_dash_separators.mjs": [null, { args: ["--check", "--bogus"] }],
-  "scripts/crawl_check.mjs": ["timeout"],
-  "scripts/gen_attribute_probes.mjs": [null],
-  "scripts/impexp.mjs": [null, { prefix: "ERROR: " }],
-  "scripts/pick_a11y_sample.mjs": ["sweep"],
-  "scripts/survey_tooling.mjs": ["root"],
-  "scripts/sweep_a11y.mjs": ["out"],
-  "scripts/sweep_attributes.mjs": ["out"],
-  "scripts/tbbuild.mjs": ["ide"],
-  "scripts/tbrun.mjs": ["ide"],
-};
-// The cases whose folder must stay empty, as for a help request: a refusal
-// starts no IDE or browser and writes nothing, and a tool that read the flag as
-// a folder name would create one.
-const LEAVES_EMPTY = new Set();
-for (const tool of Object.keys(HELP_TOOLS)) {
-  if (!(tool in REFUSALS)) throw new Error(`HELP_TOOLS names ${tool}, which REFUSALS does not`);
-}
-for (const [tool, [option, { exit = 2, prefix = "", args, empty } = {}]] of Object.entries(REFUSALS)) {
-  if (!(tool in HELP_TOOLS)) throw new Error(`REFUSALS names ${tool}, which HELP_TOOLS does not`);
-  const wanted = [
-    { args: args ?? ["--bogus"], stderr: new RegExp(`^${literal(`${prefix}unknown option: --bogus\n`)}`) },
-  ];
-  if (option)
-    wanted.push({
-      args: empty ?? [`--${option}=`],
-      stderr: new RegExp(`^${literal(`${prefix}--${option} needs a non-empty value\n`)}`),
-    });
-  for (const w of wanted) {
-    const held = CASES.find(
-      (c) => c.tool === tool && c.args.length === w.args.length && c.args.every((a, i) => a === w.args[i]),
-    );
-    if (held) LEAVES_EMPTY.add(held);
-    else {
-      const made = { tool, args: w.args, exit, stderr: w.stderr };
-      CASES.push(made);
-      LEAVES_EMPTY.add(made);
-    }
-  }
-}
-
-// A value a tool reads after the parse is checked straight after it: a number,
-// a regular expression, a URL, a date, a choice, an option that excludes
-// another. Each of these is refused before the tool starts anything, so the
-// case leaves its folder empty. `bad` is the message; a tool that prints its
-// usage after it is matched by the message and the opening of that usage. The
-// value that shows each rule is the one given: a word, 0, a fraction, a value
-// past the largest allowed, or `--x=-1`, the form that reaches the check (a
-// separate -1 is refused by the parse as a missing value).
-const BAD_VALUES = [];
-const bad = (tool, args, stderr, exit = 2) => BAD_VALUES.push({ tool, args, exit, stderr });
-// The message, then the opening of the tool's usage; `blank` when the tool puts
-// an empty line between them.
-const thenUsage = (message, tool, blank = false) =>
-  new RegExp(`^${literal(message)}\\n${blank ? "\\n" : ""}usage: node ${literal(tool)} `);
-const NOT_PORT = (v) => `--port expects a whole number from 1 to 65535, got: ${v}`;
-const NOT_COUNT = (option, v) => `${option} expects a whole number of at least 1, got: ${v}`;
-const NOT_WHOLE = (option, v) => `${option} expects a whole number of at least 0, got: ${v}`;
-const NOT_ABOVE_ZERO = (option, v) => `${option} expects a number greater than 0, got: ${v}`;
-const NOT_URL = (option, v) => `${option} expects an absolute http or https URL, got: ${v}`;
-const START = "http://127.0.0.1:9/";
-const REGEX_REASON = (option, v) =>
-  new RegExp(`^${literal(`${option} expects a regular expression, got: ${v} (`)}.+\\)\\n$`);
-
-// tbdocs prints the message alone, check_links after `error: `.
-bad("builder/tbdocs.mjs", ["--url", "foo"], NOT_URL("--url", "foo") + "\n");
-bad("builder/tbdocs.mjs", ["--url=mailto:x"], NOT_URL("--url", "mailto:x") + "\n");
-bad("builder/tbdocs.mjs", ["--stall-timeout", "abc"], "--stall-timeout expects a number of at least 0, got: abc\n");
-bad(
-  "scripts/check_links.mjs",
-  ["--offline", "--oracle", "x", "no-such-tree"],
-  "error: --oracle expects fs or index, got: x\n",
-);
-bad("scripts/check_links.mjs", ["--offline", "--oracle=", "no-such-tree"], "error: --oracle needs a non-empty value\n");
-
-// tbbuild and tbrun follow the message with their usage.
-for (const [tool, first] of [
-  ["scripts/tbbuild.mjs", "x.twinproj"],
-  ["scripts/tbrun.mjs", "no-such-dir"],
-]) {
-  bad(tool, [first, "--port", "0"], thenUsage(NOT_PORT(0), tool));
-  bad(tool, [first, "--port=65536"], thenUsage(NOT_PORT(65536), tool));
-  bad(tool, [first, "--port", "abc"], thenUsage(NOT_PORT("abc"), tool));
-  bad(tool, [first, "--timeout", "0"], thenUsage(NOT_ABOVE_ZERO("--timeout", 0), tool));
-  bad(tool, [first, "--timeout=-1"], thenUsage(NOT_ABOVE_ZERO("--timeout", -1), tool));
-  bad(tool, [first, "--arch", "WIN32"], thenUsage("--arch expects win32 or win64, got: WIN32", tool));
-  bad(tool, [first, "--show", "--hide"], thenUsage("--show and --hide cannot be given together", tool));
-}
-bad("scripts/tbrun.mjs", ["no-such-dir", "--quiet=-1"], thenUsage(NOT_WHOLE("--quiet", -1), "scripts/tbrun.mjs"));
-
-// sweep_attributes reads its values before it looks for an IDE, and follows the
-// message with its usage.
-{
-  const tool = "scripts/sweep_attributes.mjs";
-  bad(tool, ["--jobs", "0"], thenUsage(NOT_COUNT("--jobs", 0), tool));
-  bad(tool, ["--port", "0"], thenUsage(NOT_PORT(0), tool));
-  bad(tool, ["--port=65536"], thenUsage(NOT_PORT(65536), tool));
-  bad(tool, ["--port", "65535", "--jobs", "2"], thenUsage("--port 65535 with --jobs 2 runs past port 65535", tool));
-  bad(tool, ["--batch-size", "3"], thenUsage("--batch-size expects a whole number of at least 4, got: 3", tool));
-  bad(tool, ["--verify=-1"], thenUsage(NOT_WHOLE("--verify", -1), tool));
-  bad(tool, ["--timeout", "0"], thenUsage(NOT_ABOVE_ZERO("--timeout", 0), tool));
-  bad(tool, ["--forms", "some"], thenUsage("--forms expects bare, smart or all, got: some", tool));
-  bad(tool, ["--sites", "NO_SUCH_SITE"], thenUsage("unknown site: NO_SUCH_SITE (--list-sites names them)", tool));
-  // The drive root is outside the temp folder however the case is run; a relative name would resolve
-  // under it, where the case runs.
-  bad(tool, ["--work=/"], new RegExp(`^--work must be under .+, not .+\\nusage: node ${literal(tool)} `));
-  bad(tool, ["--show", "--hide"], thenUsage("--show and --hide cannot be given together", tool));
-}
-bad("scripts/tbrun.mjs", ["no-such-dir", "--quiet", "1.5"], thenUsage(NOT_WHOLE("--quiet", 1.5), "scripts/tbrun.mjs"));
-
-bad("scripts/addin_test.mjs", ["--only", "("], REGEX_REASON("--only", "("));
-bad("scripts/addin_test.mjs", ["--port", "0"], NOT_PORT(0) + "\n");
-bad("scripts/addin_test.mjs", ["--port=1.5"], NOT_PORT(1.5) + "\n");
-bad("scripts/addin_test.mjs", ["--jobs", "0"], NOT_COUNT("--jobs", 0) + "\n");
-bad("scripts/addin_test.mjs", ["--jobs=1.5"], NOT_COUNT("--jobs", 1.5) + "\n");
-bad(
-  "scripts/addin_test.mjs",
-  ["--timeout", "0"],
-  "--timeout expects a number greater than 0 and at most 2147483, got: 0\n",
-);
-bad(
-  "scripts/addin_test.mjs",
-  ["--timeout", "2147484"],
-  "--timeout expects a number greater than 0 and at most 2147483, got: 2147484\n",
-);
-bad("scripts/addin_test.mjs", ["--show", "--hide"], "--show and --hide cannot be given together\n");
-
-bad("scripts/ide_test.mjs", ["--only", "("], REGEX_REASON("--only", "("));
-bad("scripts/ide_test.mjs", ["--port", "0"], NOT_PORT(0) + "\n");
-bad("scripts/ide_test.mjs", ["--port=1.5"], NOT_PORT(1.5) + "\n");
-bad("scripts/ide_test.mjs", ["--jobs", "0"], NOT_COUNT("--jobs", 0) + "\n");
-bad("scripts/ide_test.mjs", ["--jobs=1.5"], NOT_COUNT("--jobs", 1.5) + "\n");
-bad(
-  "scripts/ide_test.mjs",
-  ["--timeout", "0"],
-  "--timeout expects a number greater than 0 and at most 2147483, got: 0\n",
-);
-bad(
-  "scripts/ide_test.mjs",
-  ["--timeout", "2147484"],
-  "--timeout expects a number greater than 0 and at most 2147483, got: 2147484\n",
-);
-bad("scripts/ide_test.mjs", ["--show", "--hide"], "--show and --hide cannot be given together\n");
-
-// check_examples prints "check_examples: " before the message.
-{
-  const tool = "scripts/check_examples.mjs";
-  const say = (message) => `check_examples: ${message}\n`;
-  bad(tool, ["--jobs", "abc"], say(NOT_COUNT("--jobs", "abc")));
-  bad(tool, ["--batch", "0"], say(NOT_COUNT("--batch", 0)));
-  bad(tool, ["--port", "0"], say(NOT_PORT(0)));
-  bad(tool, ["--port=65536"], say(NOT_PORT(65536)));
-  bad(
-    tool,
-    ["--only", "("],
-    new RegExp(`^check_examples: ${literal("--only expects a regular expression, got: ( (")}.+\\)\\n$`),
-  );
-  bad(tool, ["--apply"], say("--apply needs --propose"));
-  bad(tool, ["--apply", "--census"], say("--apply needs --propose"));
-  bad(tool, ["--census", "--propose"], say("--census and --propose cannot be given together"));
-  bad(tool, ["--report", "survey.json", "--census"], say("--report and --census cannot be given together"));
-  bad(
-    tool,
-    ["--report", "survey.json", "--census", "--propose"],
-    say("--report, --census and --propose cannot be given together"),
-  );
-  bad(tool, ["--show", "--hide"], say("--show and --hide cannot be given together"));
-}
-
-bad(
-  "scripts/survey_tooling.mjs",
-  ["--window", "abc"],
-  thenUsage(NOT_COUNT("--window", "abc"), "scripts/survey_tooling.mjs"),
-);
-bad("scripts/survey_tooling.mjs", ["--top=-1"], thenUsage(NOT_COUNT("--top", -1), "scripts/survey_tooling.mjs"));
-bad(
-  "scripts/compare_trees.mjs",
-  ["--max=-1"],
-  thenUsage(`compare_trees: ${NOT_WHOLE("--max", -1)}`, "scripts/compare_trees.mjs", true),
-);
-bad(
-  "scripts/compare_trees.mjs",
-  ["--max", "abc"],
-  thenUsage(`compare_trees: ${NOT_WHOLE("--max", "abc")}`, "scripts/compare_trees.mjs", true),
-);
-
-{
-  const tool = "scripts/crawl_check.mjs";
-  bad(tool, ["--concurrency", "0", START], thenUsage(NOT_COUNT("--concurrency", 0), tool));
-  bad(tool, ["--concurrency=1.5", START], thenUsage(NOT_COUNT("--concurrency", 1.5), tool));
-  bad(
-    tool,
-    ["--timeout", "0", START],
-    thenUsage("--timeout expects a whole number from 1 to 2147483647, got: 0", tool),
-  );
-  bad(
-    tool,
-    ["--timeout", "2147483648", START],
-    thenUsage("--timeout expects a whole number from 1 to 2147483647, got: 2147483648", tool),
-  );
-  bad(
-    tool,
-    ["--timeout", "abc", START],
-    thenUsage("--timeout expects a whole number from 1 to 2147483647, got: abc", tool),
-  );
-  bad(tool, ["foo"], thenUsage(NOT_URL("<start-url>", "foo"), tool));
-  bad(tool, ["mailto:x"], thenUsage(NOT_URL("<start-url>", "mailto:x"), tool));
-}
-
-bad("scripts/sweep_a11y.mjs", ["--limit", "0"], NOT_COUNT("--limit", 0) + "\n");
-bad("scripts/sweep_a11y.mjs", ["--limit=1.5"], NOT_COUNT("--limit", 1.5) + "\n");
-bad("scripts/sweep_a11y.mjs", ["--recycle-every", "0"], NOT_COUNT("--recycle-every", 0) + "\n");
-bad("scripts/sweep_a11y.mjs", ["--recycle-every", "abc"], NOT_COUNT("--recycle-every", "abc") + "\n");
-bad("scripts/pick_a11y_sample.mjs", ["--budget", "0"], NOT_ABOVE_ZERO("--budget", 0) + "\n");
-bad("scripts/pick_a11y_sample.mjs", ["--budget=-1"], NOT_ABOVE_ZERO("--budget", -1) + "\n");
-bad("scripts/pick_a11y_sample.mjs", ["--check", "--propose"], "--check and --propose cannot be given together\n");
-bad("scripts/pick_a11y_sample.mjs", ["--propose", "--census"], "--propose and --census cannot be given together\n");
-bad(
-  "scripts/pick_a11y_sample.mjs",
-  ["--check", "--propose", "--census"],
-  "--check, --propose and --census cannot be given together\n",
-);
-bad("scripts/check_a11y_fingerprint.mjs", ["--baseline", "nope"], /^--baseline expects production, .+, got: nope\n$/);
-bad("scripts/check_a11y_fingerprint.mjs", ["--candidate", "nope"], /^--candidate expects production, .+, got: nope\n$/);
-bad("scripts/check_a11y_fingerprint.mjs", ["--patches", "nope"], /^--patches expects .+, got: nope\n$/);
-bad("scripts/check_a11y_fingerprint.mjs", ["--patches=plain-color-fields,nope"], /^--patches expects .+, got: nope\n$/);
-bad("scripts/check_axe_patch_equiv.mjs", ["--patch", "nope"], /^--patch expects .+, got: nope\n$/);
-bad("scripts/check_links_diff.mjs", ["--max-lines", "abc"], NOT_WHOLE("--max-lines", "abc") + "\n");
-bad("scripts/check_links_diff.mjs", ["--max-lines=-1"], NOT_WHOLE("--max-lines", -1) + "\n");
-bad("scripts/check_links_diff.mjs", ["--max-lines=1.5"], NOT_WHOLE("--max-lines", 1.5) + "\n");
-
-const NOT_MS = (v) => `--timeout expects a whole number from 0 to 2147483647, got: ${v}\n`;
-bad("book/render-book.mjs", ["a.html", "-o", "out.pdf", "--timeout=-1"], NOT_MS(-1));
-bad("book/render-book.mjs", ["a.html", "-o", "out.pdf", "-t", "1.5"], NOT_MS(1.5));
-bad("book/render-book.mjs", ["a.html", "-o", "out.pdf", "-t", "2147483648"], NOT_MS(2147483648));
-
-bad("eval/run_case.mjs", ["--timeout", "0"], "--timeout expects a number greater than 0 and at most 35791, got: 0\n");
-bad(
-  "eval/run_case.mjs",
-  ["--timeout", "35792"],
-  "--timeout expects a number greater than 0 and at most 35791, got: 35792\n",
-);
-bad("eval/run_case.mjs", ["--protocol", "x"], "--protocol expects repo or site, got: x\n");
-bad("eval/search_quality.mjs", ["--sample", "0"], NOT_COUNT("--sample", 0) + "\n");
-bad("eval/search_quality.mjs", ["--worst=-1"], NOT_WHOLE("--worst", -1) + "\n");
-bad("eval/search_quality.mjs", ["--worst", "abc"], NOT_WHOLE("--worst", "abc") + "\n");
-bad("eval/search_quality.mjs", ["--failures=1.5"], NOT_WHOLE("--failures", 1.5) + "\n");
-bad("eval/site_search.mjs", ["--n", "0", "term"], NOT_COUNT("--n", 0) + "\n");
-bad("eval/site_search.mjs", ["--n=1.5", "term"], NOT_COUNT("--n", 1.5) + "\n");
-bad("eval/site_search.mjs", ["--composition", "term"], "--composition takes no search terms\n");
-bad("eval/nav_hops.mjs", ["("], REGEX_REASON("<url-regex>", "("));
-bad("eval/nav_hops.mjs", ["Reference", "[a-"], REGEX_REASON("<url-regex>", "[a-"));
-
-// build_corpus empties its --dest before it writes, so it refuses one that is or
-// contains the repository root, the folder it runs from or --repo, checked in
-// that order. Every one of these stops at the command line. Each --dest is a
-// folder that must never be emptied.
-{
-  const tool = "eval/build_corpus.mjs";
-  const refuse = (dest, what) =>
-    new RegExp(`^refusing --dest ${dest}: it is or contains ${what}, which cleaning it would delete\\n$`);
-  const docs = path.join(REPO_ROOT, "docs");
-  bad(tool, ["--dest", REPO_ROOT], refuse(literal(REPO_ROOT), "the repository root"));
-  bad(tool, ["--dest", path.dirname(REPO_ROOT)], refuse(literal(path.dirname(REPO_ROOT)), "the repository root"));
-  bad(tool, ["--dest", "."], refuse(".+", "the current folder"));
-  bad(tool, ["--dest", ".."], refuse(".+", "the current folder"));
-  bad(
-    tool,
-    ["--repo", path.join(docs, "Reference"), "--dest", docs],
-    refuse(literal(docs), literal(`--repo ${path.join(docs, "Reference")}`)),
-  );
-  bad(tool, ["--repo", docs, "--dest", docs], refuse(literal(docs), literal(`--repo ${docs}`)));
-}
-
-// wisdom's command in these is never a real one, so that none can start an
-// export, except extract, whose modes are refused before it reads a thing.
-{
-  const tool = "wisdom/wisdom.mjs";
-  const since = (v) => `--since expects an ISO 8601 date (YYYY-MM-DD) no earlier than 2015-01-01, got: ${v}\n`;
-  bad(tool, ["bogus", "--concurrency", "0"], NOT_COUNT("--concurrency", 0) + "\n");
-  bad(tool, ["bogus", "--concurrency=1.5"], NOT_COUNT("--concurrency", 1.5) + "\n");
-  bad(tool, ["bogus", "--cap=-1"], NOT_COUNT("--cap", -1) + "\n");
-  bad(tool, ["bogus", "--cap", "abc"], NOT_COUNT("--cap", "abc") + "\n");
-  bad(tool, ["bogus", "--rate-limit", "0"], NOT_ABOVE_ZERO("--rate-limit", 0) + "\n");
-  bad(tool, ["bogus", "--rate-limit", "abc"], NOT_ABOVE_ZERO("--rate-limit", "abc") + "\n");
-  bad(tool, ["bogus", "--since", "12"], since("12"));
-  bad(tool, ["bogus", "--since", "2024-02-30"], since("2024-02-30"));
-  bad(tool, ["bogus", "--since", "2014-12-31"], since("2014-12-31"));
-  bad(tool, ["bogus", "--min-confidence", "x"], "--min-confidence expects high, medium or low, got: x\n");
-  bad(tool, ["extract", "--all", "--force"], "--all and --force cannot be given together\n");
-  bad(tool, ["extract", "--since", "2024-01-01", "--force"], "--since and --force cannot be given together\n");
-  bad(
-    tool,
-    ["extract", "--since", "2024-01-01", "--all", "--force"],
-    "--since, --all and --force cannot be given together\n",
-  );
-}
-for (const made of BAD_VALUES) {
-  CASES.push(made);
-  LEAVES_EMPTY.add(made);
-}
-
 const TIMEOUT_MS = 30_000;
 
 function runCase({ tool, args }, cwd, env) {
diff --git a/scripts/lib/cli-cases.mjs b/scripts/lib/cli-cases.mjs
new file mode 100644
index 00000000..b3ab1608
--- /dev/null
+++ b/scripts/lib/cli-cases.mjs
@@ -0,0 +1,726 @@
+// The recorded cases scripts/check_cli.mjs runs: invocations that stop while
+// a tool reads its command line, each with the exit code and the text printed
+// on each stream. check_cli.mjs's opening comment says what a case asserts and
+// which invocations belong here; this module only builds the list.
+//
+// CASES is the hand-written table, then the cases generated from HELP_TOOLS
+// (--help and -h for every tool), REFUSALS (an unknown flag and an empty value
+// for every tool) and BAD_VALUES (a value refused straight after the parse).
+// LEAVES_EMPTY holds the cases whose folder must still be empty afterwards.
+// A new tool goes into HELP_TOOLS and REFUSALS; building the list throws if
+// the two disagree.
+
+import path from "node:path";
+import { REPO_ROOT } from "../../lib/repo-paths.mjs";
+
+// biome-ignore format: a table, one entry per line
+const CASES = [
+  // A command-line error in tbdocs and check_links exits 2, as in every tool,
+  // and never reads as a finding, which exits 1. A value flag has no
+  // value at the end of the list or before another flag, and --port is a whole
+  // number from 1 to 65535. check_links prints its errors on stderr, after
+  // "error: ".
+  { tool: "builder/tbdocs.mjs", args: ["--port"], exit: 2, stderr: "--port needs a value\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--dest", "--no-pdf"], exit: 2, stderr: "--dest needs a value\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--port=0"], exit: 2, stderr: "--port expects a whole number from 1 to 65535, got: 0\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "scripts/check_links.mjs", args: ["no-such-tree", "--root-dir"], exit: 2, stderr: "error: --root-dir needs a value\n" },
+  { tool: "scripts/check_links.mjs", args: ["no-such-tree", "--forbid"], exit: 2, stderr: "error: --forbid needs a value\n" },
+
+  // In the four harness tools that check, a value flag with no value, at the end or before another flag,
+  // exits 2. tbbuild follows the message with its usage line.
+  { tool: "scripts/tbbuild.mjs", args: ["--port"], exit: 2, stderr: /^--port needs a value\nusage: node scripts\/tbbuild\.mjs / },
+  { tool: "scripts/tbbuild.mjs", args: ["--timeout", "--keep"], exit: 2, stderr: /^--timeout needs a value\nusage: node scripts\/tbbuild\.mjs / },
+  { tool: "scripts/check_examples.mjs", args: ["--jobs"], exit: 2, stderr: "check_examples: --jobs needs a value\n" },
+  { tool: "scripts/check_examples.mjs", args: ["--port", "--json"], exit: 2, stderr: "check_examples: --port needs a value\n" },
+  { tool: "scripts/census_attributes.mjs", args: ["--out"], exit: 2, stderr: "--out needs a value\n" },
+  { tool: "scripts/census_attributes.mjs", args: ["--exported", "--json"], exit: 2, stderr: "--exported needs a value\n" },
+  { tool: "scripts/census_attributes.mjs", args: ["--src", "x"], exit: 2, stderr: "unknown option: --src\n" },
+  { tool: "scripts/build_package_api.mjs", args: ["--out"], exit: 2, stderr: "--out needs a value\n" },
+  { tool: "scripts/build_package_api.mjs", args: ["--exported", "--check"], exit: 2, stderr: "--exported needs a value\n" },
+  { tool: "scripts/build_package_api.mjs", args: ["--src", "x"], exit: 2, stderr: "unknown option: --src\n" },
+
+  // The a11y and diagram tools. A value flag given
+  // nothing, at the end or as "", or followed by another flag, is refused.
+  // Each of them answers --help on stdout with exit 0.
+  // --theme and --viewport are checked against their lists.
+  // check_dot_fit and build_dot_metrics take one flag of their own besides
+  // --help and -h, and neither has a case beyond those and the generated ones.
+  { tool: "scripts/check_a11y.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/check_a11y\.mjs / },
+  { tool: "scripts/check_a11y.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "scripts/check_a11y.mjs", args: ["--root-dir"], exit: 2, stderr: "--root-dir needs a value\n" },
+  { tool: "scripts/check_a11y.mjs", args: ["--root-dir", "--theme", "dark"], exit: 2, stderr: "--root-dir needs a value\n" },
+  { tool: "scripts/check_a11y.mjs", args: ["--theme", ""], exit: 2, stderr: "--theme needs a non-empty value\n" },
+  { tool: "scripts/check_a11y.mjs", args: ["--theme", "drak"], exit: 2, stderr: 'unknown --theme "drak"; expected one of light, dark or both\n' },
+  { tool: "scripts/check_a11y.mjs", args: ["--viewport", "huge"], exit: 2, stderr: 'unknown --viewport "huge"; expected one of desktop, mobile or both\n' },
+  { tool: "scripts/check_a11y_fingerprint.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/check_a11y_fingerprint\.mjs / },
+  { tool: "scripts/check_a11y_fingerprint.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "scripts/check_a11y_fingerprint.mjs", args: ["--pages"], exit: 2, stderr: "--pages needs a value\n" },
+  { tool: "scripts/check_a11y_fingerprint.mjs", args: ["--out"], exit: 2, stderr: "--out needs a value\n" },
+  { tool: "scripts/check_a11y_fingerprint.mjs", args: ["--json", "x"], exit: 2, stderr: "unknown option: --json\n" },
+  { tool: "scripts/check_a11y_fingerprint.mjs", args: ["--theme", "drak"], exit: 2, stderr: 'unknown --theme "drak"; expected one of light, dark or both\n' },
+  { tool: "scripts/check_axe_patch_equiv.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/check_axe_patch_equiv\.mjs / },
+  { tool: "scripts/check_axe_patch_equiv.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "scripts/check_axe_patch_equiv.mjs", args: ["--patch"], exit: 2, stderr: "--patch needs a value\n" },
+  { tool: "scripts/check_pdf_shims_equiv.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/check_pdf_shims_equiv\.mjs\n/ },
+  { tool: "scripts/check_pdf_shims_equiv.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "scripts/check_impexp_parity.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/check_impexp_parity\.mjs\n/ },
+  { tool: "scripts/check_impexp_parity.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "scripts/check_tree_fresh.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/check_tree_fresh\.mjs / },
+  { tool: "scripts/check_tree_fresh.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "scripts/check_tree_fresh.mjs", args: ["--source"], exit: 2, stderr: "--source needs a value\n" },
+  { tool: "scripts/check_tree_fresh.mjs", args: ["--tree"], exit: 2, stderr: "--tree needs a value\n" },
+  { tool: "scripts/pick_a11y_sample.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/pick_a11y_sample\.mjs / },
+  { tool: "scripts/pick_a11y_sample.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "scripts/pick_a11y_sample.mjs", args: ["--budget"], exit: 2, stderr: "--budget needs a value\n" },
+  { tool: "scripts/sweep_a11y.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/sweep_a11y\.mjs / },
+  { tool: "scripts/sweep_a11y.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "scripts/sweep_a11y.mjs", args: ["--limit"], exit: 2, stderr: "--limit needs a value\n" },
+  { tool: "scripts/sweep_a11y.mjs", args: ["--theme", "drak"], exit: 2, stderr: 'unknown --theme "drak"; expected one of light, dark or both\n' },
+  { tool: "scripts/sweep_a11y.mjs", args: ["--viewport", "huge"], exit: 2, stderr: 'unknown --viewport "huge"; expected one of desktop, mobile or both\n' },
+
+  // The harness tools. All of them answer --help and -h
+  // on stdout with exit 0 before any other check, a number or a missing
+  // project included. tbbuild finds its project anywhere in the list.
+  // An unknown option, a value flag with no value or an empty one is
+  // refused, and tbbuild and tbrun follow the message with their usage.
+  // gen_attribute_probes takes one output folder and an optional key file, so
+  // only its empty list is a case here.
+  { tool: "scripts/tbbuild.mjs", args: [], exit: 2, stderr: /^usage: node scripts\/tbbuild\.mjs / },
+  { tool: "scripts/tbbuild.mjs", args: ["x.twinproj", "--help"], exit: 0, stdout: /^usage: node scripts\/tbbuild\.mjs / },
+  { tool: "scripts/tbbuild.mjs", args: ["x.twinproj", "--arch", "win99"], exit: 2, stderr: /^--arch expects win32 or win64, got: win99\nusage: node scripts\/tbbuild\.mjs / },
+  { tool: "scripts/tbbuild.mjs", args: ["x.twinproj", "--port", "1.5"], exit: 2, stderr: /^--port expects a whole number from 1 to 65535, got: 1\.5\nusage: node scripts\/tbbuild\.mjs / },
+  { tool: "scripts/tbbuild.mjs", args: ["x.twinproj", "--timeout", "abc"], exit: 2, stderr: /^--timeout expects a number greater than 0, got: abc\nusage: node scripts\/tbbuild\.mjs / },
+  { tool: "scripts/tbbuild.mjs", args: ["x.twinproj", "--timeout", "-3"], exit: 2, stderr: /^--timeout needs a value\nusage: node scripts\/tbbuild\.mjs / },
+  { tool: "scripts/tbbuild.mjs", args: ["x.twinproj", "--port", "0", "--help"], exit: 0, stdout: /^usage: node scripts\/tbbuild\.mjs / },
+  { tool: "scripts/tbbuild.mjs", args: ["--bogus", "--keep", "x.twinproj"], exit: 2, stderr: /^unknown option: --bogus\nusage: node scripts\/tbbuild\.mjs / },
+  { tool: "scripts/tbbuild.mjs", args: ["--keep", "x.twinproj"], exit: 2, stderr: "no such project: x.twinproj\n" },
+  { tool: "scripts/tbrun.mjs", args: [], exit: 2, stderr: /^usage: node scripts\/tbrun\.mjs / },
+  { tool: "scripts/tbrun.mjs", args: ["no-such-dir", "--help"], exit: 0, stdout: /^usage: node scripts\/tbrun\.mjs / },
+  { tool: "scripts/tbrun.mjs", args: ["no-such-dir", "--arch", "win99"], exit: 2, stderr: /^--arch expects win32 or win64, got: win99\nusage: node scripts\/tbrun\.mjs / },
+  { tool: "scripts/tbrun.mjs", args: ["--port", "no-such-dir"], exit: 2, stderr: /^--port expects a whole number from 1 to 65535, got: no-such-dir\nusage: node scripts\/tbrun\.mjs / },
+  { tool: "scripts/tbrun.mjs", args: ["no-such-dir", "--arch"], exit: 2, stderr: /^--arch needs a value\nusage: node scripts\/tbrun\.mjs / },
+  { tool: "scripts/tbrun.mjs", args: ["no-such-dir", "--arch", ""], exit: 2, stderr: /^--arch needs a non-empty value\nusage: node scripts\/tbrun\.mjs / },
+  { tool: "scripts/tbrun.mjs", args: ["--bogus", "no-such-dir"], exit: 2, stderr: /^unknown option: --bogus\nusage: node scripts\/tbrun\.mjs / },
+  { tool: "scripts/tbrun.mjs", args: ["no-such-dir", "--arch", "win64"], exit: 2, stderr: /^not a directory: .*no-such-dir\ntbrun takes an exported source tree / },
+  { tool: "scripts/addin_test.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/addin_test\.mjs / },
+  { tool: "scripts/addin_test.mjs", args: ["--ide"], exit: 2, stderr: "--ide needs a value\n" },
+  { tool: "scripts/addin_test.mjs", args: ["--ide", ""], exit: 2, stderr: "--ide needs a non-empty value\n" },
+  { tool: "scripts/addin_test.mjs", args: ["--ide", "no-such.exe"], exit: 2, stderr: /^no twinBASIC IDE found: pass --ide / },
+  { tool: "scripts/ide_test.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/ide_test\.mjs / },
+  { tool: "scripts/ide_test.mjs", args: ["--ide"], exit: 2, stderr: "--ide needs a value\n" },
+  { tool: "scripts/ide_test.mjs", args: ["--ide", ""], exit: 2, stderr: "--ide needs a non-empty value\n" },
+  { tool: "scripts/ide_test.mjs", args: ["--ide", "no-such.exe"], exit: 2, stderr: /^no twinBASIC IDE found: pass --ide / },
+  { tool: "scripts/check_examples.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/check_examples\.mjs \[options\]\n/ },
+  { tool: "scripts/check_examples.mjs", args: ["--jobs", "0"], exit: 2, stderr: "check_examples: --jobs expects a whole number of at least 1, got: 0\n" },
+  { tool: "scripts/check_examples.mjs", args: ["--batch", "1.5"], exit: 2, stderr: "check_examples: --batch expects a whole number of at least 1, got: 1.5\n" },
+  { tool: "scripts/check_examples.mjs", args: ["--jobs", "0", "--help"], exit: 0, stdout: /^usage: node scripts\/check_examples\.mjs \[options\]\n/ },
+  { tool: "scripts/check_examples.mjs", args: ["--help", "--jobs"], exit: 0, stdout: /^usage: node scripts\/check_examples\.mjs \[options\]\n/ },
+  { tool: "scripts/census_attributes.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/census_attributes\.mjs \[options\]\n/ },
+  { tool: "scripts/census_attributes.mjs", args: ["--help", "--attr"], exit: 0, stdout: /^usage: node scripts\/census_attributes\.mjs \[options\]\n/ },
+  { tool: "scripts/census_attributes.mjs", args: ["--dump-sites"], exit: 2, stderr: "--dump-sites needs a value\n" },
+  { tool: "scripts/build_package_api.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/build_package_api\.mjs \[options\]\n/ },
+  { tool: "scripts/gen_attribute_probes.mjs", args: [], exit: 2, stderr: /^Generate a twinBASIC probe project for Reference\/Attributes\.md applicability\.\n/ },
+
+  // The gates and link tools. check_links prints its
+  // errors on stderr, after "error: ", and exits 2. Every one of them refuses
+  // an unknown option, a stray argument, a value given to a flag that takes
+  // none, and a value flag with no value, and crawl_check, compare_trees and
+  // survey_tooling follow the message with their usage. check_lint prints its
+  // name, the message and its usage line. check_regex_safety,
+  // check_code_regions, check_gate_lists and convert_em_dash_separators take
+  // only flags of their own, and none has a case beyond --help, -h and the
+  // generated ones below.
+  { tool: "scripts/check_links.mjs", args: ["--help"], exit: 0, stdout: /^Usage: node check_links\.mjs \[options\] <inputs\.\.\.>\n/ },
+  { tool: "scripts/check_links.mjs", args: ["no-such-tree"], exit: 2, stderr: "error: --offline is required. Online (network) checking is not implemented by this tool.\n" },
+  { tool: "scripts/check_links.mjs", args: ["--offline"], exit: 2, stderr: "error: at least one input file or directory is required\n" },
+  { tool: "scripts/check_links.mjs", args: ["--offline", "--bogus", "no-such-tree"], exit: 2, stderr: "error: unknown option: --bogus\n" },
+  { tool: "scripts/check_links.mjs", args: ["--offline", "-x", "--bogus=1"], exit: 2, stderr: "error: unknown option: -x\n" },
+  { tool: "scripts/check_links.mjs", args: ["--offline", "--root-dir", "--forbid"], exit: 2, stderr: "error: --root-dir needs a value\n" },
+  { tool: "scripts/check_links_diff.mjs", args: ["--help"], exit: 0, stdout: /^Usage: node scripts\/check_links_diff\.mjs \[options\]\n/ },
+  { tool: "scripts/check_links_diff.mjs", args: [], exit: 2, stderr: /^error: --a and --b are both 'script', which compares nothing\.\n/ },
+  { tool: "scripts/check_links_diff.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "scripts/check_links_diff.mjs", args: ["stray"], exit: 2, stderr: "unexpected argument: stray\n" },
+  { tool: "scripts/check_links_diff.mjs", args: ["--list=1"], exit: 2, stderr: "--list takes no value\n" },
+  { tool: "scripts/crawl_check.mjs", args: [], exit: 2, stderr: /^usage: node scripts\/crawl_check\.mjs <start-url> / },
+  { tool: "scripts/crawl_check.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/crawl_check\.mjs <start-url> / },
+  { tool: "scripts/crawl_check.mjs", args: ["--bogus", "http://127.0.0.1:9/"], exit: 2, stderr: /^unknown option: --bogus\nusage: node scripts\/crawl_check\.mjs <start-url> / },
+  { tool: "scripts/crawl_check.mjs", args: ["--timeout", "5", "-x"], exit: 2, stderr: /^unknown option: -x\nusage: node scripts\/crawl_check\.mjs <start-url> / },
+  { tool: "scripts/crawl_check.mjs", args: ["--skip-external=1"], exit: 2, stderr: /^--skip-external takes no value\nusage: node scripts\/crawl_check\.mjs <start-url> / },
+  { tool: "scripts/crawl_check.mjs", args: ["--concurrency", "--bogus"], exit: 2, stderr: /^--concurrency needs a value\nusage: node scripts\/crawl_check\.mjs <start-url> / },
+  { tool: "scripts/check_publish_policy.mjs", args: ["--src"], exit: 2, stderr: "--src needs a value\n" },
+  { tool: "scripts/survey_tooling.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/survey_tooling\.mjs \[--root DIR\] / },
+  { tool: "scripts/survey_tooling.mjs", args: ["--bogus"], exit: 2, stderr: /^unknown option: --bogus\nusage: node scripts\/survey_tooling\.mjs \[--root DIR\] / },
+  { tool: "scripts/survey_tooling.mjs", args: ["stray"], exit: 2, stderr: /^unexpected argument: stray\nusage: node scripts\/survey_tooling\.mjs \[--root DIR\] / },
+  { tool: "scripts/survey_tooling.mjs", args: ["--root"], exit: 2, stderr: /^--root needs a value\nusage: node scripts\/survey_tooling\.mjs \[--root DIR\] / },
+  { tool: "scripts/survey_tooling.mjs", args: ["--window", "0"], exit: 2, stderr: /^--window expects a whole number of at least 1, got: 0\nusage: node scripts\/survey_tooling\.mjs / },
+  { tool: "scripts/survey_tooling.mjs", args: ["--top", "1.5"], exit: 2, stderr: /^--top expects a whole number of at least 1, got: 1\.5\nusage: node scripts\/survey_tooling\.mjs / },
+  { tool: "scripts/survey_tooling.mjs", args: ["--window", "0", "--help"], exit: 0, stdout: /^usage: node scripts\/survey_tooling\.mjs \[--root DIR\] / },
+  { tool: "scripts/check_lint.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/check_lint\.mjs \[--staged\]\n/ },
+  { tool: "scripts/check_lint.mjs", args: ["--staged", "--staged"], exit: 2, stderr: "check_lint: --staged given more than once\nusage: node scripts/check_lint.mjs [--staged]\n" },
+  { tool: "scripts/check_lint.mjs", args: ["--staged", "x"], exit: 2, stderr: "check_lint: unexpected argument: x\nusage: node scripts/check_lint.mjs [--staged]\n" },
+  { tool: "scripts/check_lint.mjs", args: ["--"], exit: 2, stderr: "check_lint: unexpected argument: --\nusage: node scripts/check_lint.mjs [--staged]\n" },
+  { tool: "scripts/check_lint.mjs", args: ["--staged=1"], exit: 2, stderr: "check_lint: --staged takes no value\nusage: node scripts/check_lint.mjs [--staged]\n" },
+  { tool: "scripts/check_lint.mjs", args: ["--bogus"], exit: 2, stderr: "check_lint: unknown option: --bogus\nusage: node scripts/check_lint.mjs [--staged]\n" },
+  { tool: "scripts/compare_trees.mjs", args: ["--help"], exit: 0, stdout: /^usage: node scripts\/compare_trees\.mjs \[--before <ref>\] / },
+  { tool: "scripts/compare_trees.mjs", args: ["--bogus"], exit: 2, stderr: /^compare_trees: unknown option: --bogus\n\nusage: node scripts\/compare_trees\.mjs / },
+  { tool: "scripts/compare_trees.mjs", args: ["stray"], exit: 2, stderr: /^compare_trees: unexpected argument: stray\n\nusage: node scripts\/compare_trees\.mjs / },
+  { tool: "scripts/compare_trees.mjs", args: ["--before"], exit: 2, stderr: /^compare_trees: --before needs a value\n\nusage: node scripts\/compare_trees\.mjs / },
+  { tool: "scripts/compare_trees.mjs", args: ["--max", "--keep"], exit: 2, stderr: /^compare_trees: --max needs a value\n\nusage: node scripts\/compare_trees\.mjs / },
+  { tool: "scripts/compare_trees.mjs", args: ["--max", "1.5"], exit: 2, stderr: /^compare_trees: --max expects a whole number of at least 0, got: 1\.5\n\nusage: node scripts\/compare_trees\.mjs / },
+  { tool: "scripts/compare_trees.mjs", args: ["--bogus", "--help"], exit: 2, stderr: /^compare_trees: unknown option: --bogus\n\nusage: node scripts\/compare_trees\.mjs / },
+  { tool: "scripts/compare_trees.mjs", args: ["--before", "--", "x"], exit: 2, stderr: /^compare_trees: --before needs a value\n\nusage: node scripts\/compare_trees\.mjs / },
+  { tool: "scripts/compare_trees.mjs", args: ["--keep=1"], exit: 2, stderr: /^compare_trees: --keep takes no value\n\nusage: node scripts\/compare_trees\.mjs / },
+
+  // render-book, eval/ and wisdom. In every one of them an
+  // unknown option, a value flag with no value and a value given to a boolean
+  // are refused at the parse, in the parser's own words, exit 2, and so is an
+  // argument beyond those a tool takes (nav_hops and site_search take any
+  // number). A search term or a file name that starts with a dash goes after
+  // --. build_corpus, nav_hops, run_case, site_search and transcript print
+  // their usage on stderr when an argument they need is
+  // missing; wisdom does when no command is given, and names an unknown one.
+  // Every tool here answers -h and --help on stdout with exit 0, and
+  // reads nothing after it. The command in the wisdom cases is never a real
+  // one, so that none can start an export. render-book's missing input file is
+  // not a usage error, but exits 2 as one does, and so does a --site that holds
+  // no search index.
+  { tool: "book/render-book.mjs", args: ["--help"], exit: 0, stdout: /^usage: node render-book\.mjs <input\.html> / },
+  { tool: "book/render-book.mjs", args: [], exit: 2, stderr: "usage: node render-book.mjs <input.html> -o <output.pdf> [--outline-tags ...] [-t ms] [--additional-script path]...\n" },
+  { tool: "book/render-book.mjs", args: ["a.html", "b.html"], exit: 2, stderr: "unexpected argument: b.html\n" },
+  { tool: "book/render-book.mjs", args: ["a.html", "-o"], exit: 2, stderr: "-o needs a value\n" },
+  { tool: "book/render-book.mjs", args: ["-o", "--bogus", "a.html"], exit: 2, stderr: "-o needs a value\n" },
+  { tool: "book/render-book.mjs", args: ["a.html", "-o", "out.pdf", "--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "book/render-book.mjs", args: ["a.html", "-o", "out.pdf", "--outline-tags"], exit: 2, stderr: "--outline-tags needs a value\n" },
+  { tool: "book/render-book.mjs", args: ["a.html", "-o", "out.pdf", "-t", "abc"], exit: 2, stderr: "--timeout expects a whole number from 0 to 2147483647, got: abc\n" },
+  { tool: "book/render-book.mjs", args: ["-x"], exit: 2, stderr: "unknown option: -x\n" },
+  { tool: "eval/build_corpus.mjs", args: ["--help"], exit: 0, stdout: /^Usage: node eval\/build_corpus\.mjs --dest <path> / },
+  { tool: "eval/build_corpus.mjs", args: [], exit: 2, stderr: /^Usage: node eval\/build_corpus\.mjs --dest <path> / },
+  { tool: "eval/build_corpus.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "eval/build_corpus.mjs", args: ["stray"], exit: 2, stderr: "unexpected argument: stray\n" },
+  { tool: "eval/build_corpus.mjs", args: ["--help", "--bogus"], exit: 0, stdout: /^Usage: node eval\/build_corpus\.mjs --dest <path> / },
+  { tool: "eval/build_corpus.mjs", args: ["--quiet=1"], exit: 2, stderr: "--quiet takes no value\n" },
+  { tool: "eval/build_corpus.mjs", args: ["-hq"], exit: 0, stdout: /^Usage: node eval\/build_corpus\.mjs --dest <path> / },
+  { tool: "eval/build_corpus.mjs", args: ["--repo"], exit: 2, stderr: "--repo needs a value\n" },
+  { tool: "eval/build_corpus.mjs", args: ["--src", "x"], exit: 2, stderr: "unknown option: --src\n" },
+  { tool: "eval/nav_hops.mjs", args: ["--help"], exit: 0, stdout: /^Usage: node eval\/nav_hops\.mjs \[--from <page>\] / },
+  { tool: "eval/nav_hops.mjs", args: [], exit: 2, stderr: /^Usage: node eval\/nav_hops\.mjs \[--from <page>\] / },
+  { tool: "eval/nav_hops.mjs", args: ["--from", "nope.md", "x"], exit: 2, stderr: /^no start page: .*[\\/]nope\.md\n$/ },
+  { tool: "eval/nav_hops.mjs", args: ["--repo", "nowhere", "--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "eval/nav_hops.mjs", args: ["--repo", "nowhere", "--", "--bogus"], exit: 2, stderr: /^no start page: .*[\\/]nowhere[\\/]docs[\\/]index\.md\n$/ },
+  { tool: "eval/nav_hops.mjs", args: ["--help=1", "--repo", "nowhere"], exit: 2, stderr: "--help takes no value\n" },
+  { tool: "eval/nav_hops.mjs", args: ["--from", "--repo", "x"], exit: 2, stderr: "--from needs a value\n" },
+  { tool: "eval/nav_hops.mjs", args: ["--src", "x", "y"], exit: 2, stderr: "unknown option: --src\n" },
+  { tool: "eval/nav_hops.mjs", args: ["--", "C:/x"], exit: 2, stderr: "these patterns arrived as Windows paths: C:/x\nGit Bash converted them. Run with MSYS_NO_PATHCONV=1 set, or from another shell.\n" },
+  { tool: "eval/nav_hops.mjs", args: ["--repo"], exit: 2, stderr: "--repo needs a value\n" },
+  { tool: "eval/nav_hops.mjs", args: ["x", "--from"], exit: 2, stderr: "--from needs a value\n" },
+  { tool: "eval/run_case.mjs", args: ["--help"], exit: 0, stdout: /^Usage: node eval\/run_case\.mjs --corpus <dir> / },
+  { tool: "eval/run_case.mjs", args: [], exit: 2, stderr: /^Usage: node eval\/run_case\.mjs --corpus <dir> / },
+  { tool: "eval/run_case.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "eval/run_case.mjs", args: ["stray"], exit: 2, stderr: "unexpected argument: stray\n" },
+  { tool: "eval/run_case.mjs", args: ["--help", "--bogus"], exit: 0, stdout: /^Usage: node eval\/run_case\.mjs --corpus <dir> / },
+  { tool: "eval/run_case.mjs", args: ["--prompt-only=1"], exit: 2, stderr: "--prompt-only takes no value\n" },
+  { tool: "eval/run_case.mjs", args: ["--corpus"], exit: 2, stderr: "--corpus needs a value\n" },
+  { tool: "eval/run_case.mjs", args: ["--smoke", "--corpus", "c", "--site", "s", "--out", "o"], exit: 2, stderr: /^missing: .*[\\/]c[\\/]docs, .*search-data\.json, .*lunr\.min\.js\n$/ },
+  { tool: "eval/run_case.mjs", args: ["--smoke", "--corpus", "c", "--site", "s", "--out", "o", "--timeout", "abc"], exit: 2, stderr: "--timeout expects a number greater than 0 and at most 35791, got: abc\n" },
+  { tool: "eval/run_case.mjs", args: ["--corpus", "c", "--site", "s", "--out", "o", "--protocol", "repo"], exit: 2, stderr: /^Usage: node eval\/run_case\.mjs --corpus <dir> / },
+  { tool: "eval/run_case.mjs", args: ["--corpus", "c", "--site", "s", "--out", "o", "--protocol", "--smoke"], exit: 2, stderr: "--protocol needs a value\n" },
+  { tool: "eval/site_search.mjs", args: ["--help"], exit: 0, stdout: /^Usage: node eval\/site_search\.mjs "<query>" / },
+  { tool: "eval/site_search.mjs", args: [], exit: 2, stderr: /^Usage: node eval\/site_search\.mjs "<query>" / },
+  { tool: "eval/site_search.mjs", args: ["--site", "nowhere", "--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "eval/site_search.mjs", args: ["--site", "nowhere", "--", "--bogus"], exit: 2, stderr: /^missing .*search-data\.json\nRun build\.bat / },
+  { tool: "eval/site_search.mjs", args: ["--help=1", "--site", "nowhere"], exit: 2, stderr: "--help takes no value\n" },
+  { tool: "eval/site_search.mjs", args: ["--composition", "--site", "nowhere"], exit: 2, stderr: /^missing .*search-data\.json\nRun build\.bat / },
+  { tool: "eval/site_search.mjs", args: ["--site"], exit: 2, stderr: "--site needs a value\n" },
+  { tool: "eval/search_quality.mjs", args: ["--help"], exit: 0, stdout: /^Usage: node eval\/search_quality\.mjs \[--site docs\/_site\] / },
+  { tool: "eval/search_quality.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "eval/search_quality.mjs", args: ["stray"], exit: 2, stderr: "unexpected argument: stray\n" },
+  { tool: "eval/search_quality.mjs", args: ["--help", "--bogus"], exit: 0, stdout: /^Usage: node eval\/search_quality\.mjs \[--site docs\/_site\] / },
+  { tool: "eval/search_quality.mjs", args: ["--help=1"], exit: 2, stderr: "--help takes no value\n" },
+  { tool: "eval/search_quality.mjs", args: ["-x"], exit: 2, stderr: "unknown option: -x\n" },
+  { tool: "eval/search_quality.mjs", args: ["--site", "nowhere"], exit: 2, stderr: /^missing .*search-data\.json\nRun build\.bat / },
+  { tool: "eval/search_quality.mjs", args: ["--site", "nowhere", "--sample", "abc"], exit: 2, stderr: "--sample expects a whole number of at least 1, got: abc\n" },
+  { tool: "eval/search_quality.mjs", args: ["--site", "--help"], exit: 2, stderr: "--site needs a value\n" },
+  { tool: "eval/search_quality.mjs", args: ["--site"], exit: 2, stderr: "--site needs a value\n" },
+  { tool: "eval/search_quality.mjs", args: ["--site", "nowhere", "--save"], exit: 2, stderr: "--save needs a value\n" },
+  { tool: "eval/transcript.mjs", args: ["--help"], exit: 0, stdout: /^Usage: node eval\/transcript\.mjs <case\.jsonl> / },
+  { tool: "eval/transcript.mjs", args: ["-h"], exit: 0, stdout: /^Usage: node eval\/transcript\.mjs <case\.jsonl> / },
+  { tool: "eval/transcript.mjs", args: [], exit: 2, stderr: /^Usage: node eval\/transcript\.mjs <case\.jsonl> / },
+  { tool: "eval/transcript.mjs", args: ["nope.jsonl", "--help"], exit: 0, stdout: /^Usage: node eval\/transcript\.mjs <case\.jsonl> / },
+  { tool: "eval/transcript.mjs", args: ["--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "eval/transcript.mjs", args: ["--help=1"], exit: 2, stderr: "--help takes no value\n" },
+  { tool: "eval/transcript.mjs", args: ["nope.jsonl"], exit: 2, stderr: /Error: ENOENT: no such file or directory, open '[^']*nope\.jsonl'\r?\n/ },
+  { tool: "eval/transcript.mjs", args: ["--bogus", "nope.jsonl"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "eval/transcript.mjs", args: ["-x"], exit: 2, stderr: "unknown option: -x\n" },
+  { tool: "eval/transcript.mjs", args: ["--", "-x"], exit: 2, stderr: /Error: ENOENT: no such file or directory, open '(?:[^']*[\\/])?-x'\r?\n/ },
+  { tool: "eval/transcript.mjs", args: ["a.jsonl", "b.jsonl"], exit: 2, stderr: "unexpected argument: b.jsonl\n" },
+  { tool: "wisdom/wisdom.mjs", args: [], exit: 2, stderr: /^Usage: node wisdom\/wisdom\.mjs <command> \[options\]\n/ },
+  { tool: "wisdom/wisdom.mjs", args: ["--help"], exit: 0, stdout: /^Usage: node wisdom\/wisdom\.mjs <command> \[options\]\n/ },
+  { tool: "wisdom/wisdom.mjs", args: ["bogus"], exit: 2, stderr: /^unknown command: bogus\nUsage: node wisdom\/wisdom\.mjs <command> \[options\]\n/ },
+  { tool: "wisdom/wisdom.mjs", args: ["bogus", "--guild", "--bogus"], exit: 2, stderr: "--guild needs a value\n" },
+  { tool: "wisdom/wisdom.mjs", args: ["bogus", "--cap"], exit: 2, stderr: "--cap needs a value\n" },
+  { tool: "wisdom/wisdom.mjs", args: ["bogus", "--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "wisdom/wisdom.mjs", args: ["bogus", "stray"], exit: 2, stderr: "unexpected argument: stray\n" },
+  { tool: "wisdom/wisdom.mjs", args: ["bogus", "--help"], exit: 0, stdout: /^Usage: node wisdom\/wisdom\.mjs <command> \[options\]\n/ },
+  { tool: "wisdom/wisdom.mjs", args: ["bogus", "--force=1"], exit: 2, stderr: "--force takes no value\n" },
+  { tool: "wisdom/wisdom.mjs", args: ["bogus", "-x"], exit: 2, stderr: "unknown option: -x\n" },
+  { tool: "wisdom/wisdom.mjs", args: ["bogus", "--guild", "x", "--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+
+  // tbdocs, beyond the cases above. Every command-line
+  // error exits 2. A value flag refuses a missing value and one that starts
+  // with a dash, "--" included; an unknown option is refused as given, as is a
+  // positional, and a boolean given a value. Each --port and --stall-timeout
+  // is checked where it stands, so a bad one fails even when a later one is
+  // good. A --dest the build refuses exits 2 too, after the command line has
+  // been read. --baseurl takes an empty value, meaning the site root; the
+  // other value flags refuse one.
+  { tool: "builder/tbdocs.mjs", args: ["--src"], exit: 2, stderr: "--src needs a value\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--url"], exit: 2, stderr: "--url needs a value\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--check-findings"], exit: 2, stderr: "--check-findings needs a value\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--symbol-gaps", "--serve"], exit: 2, stderr: "--symbol-gaps needs a value\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--dest", "--"], exit: 2, stderr: "--dest needs a value\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--stall-timeout"], exit: 2, stderr: "--stall-timeout needs a value\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--stall-timeout", "-1"], exit: 2, stderr: "--stall-timeout needs a value\n" },
+  { tool: "builder/tbdocs.mjs", args: ["foo"], exit: 2, stderr: "unexpected argument: foo\n" },
+  { tool: "builder/tbdocs.mjs", args: ["-"], exit: 2, stderr: "unexpected argument: -\n" },
+  { tool: "builder/tbdocs.mjs", args: ["-x"], exit: 2, stderr: "unknown option: -x\n" },
+  { tool: "builder/tbdocs.mjs", args: ["-xy"], exit: 2, stderr: "unknown option: -xy\n" },
+  { tool: "builder/tbdocs.mjs", args: ["-h"], exit: 0, stdout: /^usage: node builder\/tbdocs\.mjs \[options\]\n/ },
+  { tool: "builder/tbdocs.mjs", args: ["--help"], exit: 0, stdout: /^usage: node builder\/tbdocs\.mjs \[options\]\n/ },
+  { tool: "builder/tbdocs.mjs", args: ["--dry-run=1"], exit: 2, stderr: "--dry-run takes no value\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--no-check=1"], exit: 2, stderr: "--no-check takes no value\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--no-check", "--bogus"], exit: 2, stderr: "unknown option: --bogus\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--port", "abc"], exit: 2, stderr: "--port expects a whole number from 1 to 65535, got: abc\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--port="], exit: 2, stderr: "--port needs a non-empty value\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--stall-timeout="], exit: 2, stderr: "--stall-timeout needs a non-empty value\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--port=65536"], exit: 2, stderr: "--port expects a whole number from 1 to 65535, got: 65536\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--port=1.5"], exit: 2, stderr: "--port expects a whole number from 1 to 65535, got: 1.5\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--port=80", "--port=0"], exit: 2, stderr: "--port expects a whole number from 1 to 65535, got: 0\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--port=abc", "--port=80"], exit: 2, stderr: "--port expects a whole number from 1 to 65535, got: abc\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--stall-timeout=-1"], exit: 2, stderr: "--stall-timeout expects a number of at least 0, got: -1\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--stall-timeout=abc"], exit: 2, stderr: "--stall-timeout expects a number of at least 0, got: abc\n" },
+  { tool: "builder/tbdocs.mjs", args: ["--src", ".", "--dest", "."], exit: 2,
+    stderr: /^refusing --dest (.+): it is or contains the source tree \1, which cleaning it would delete\n$/ },
+  { tool: "builder/tbdocs.mjs", args: ["--src=.", "--dest=sub"], exit: 2,
+    stderr: /^refusing --dest (.+)[\\/]sub: it is inside the source tree, so a build would read its output back as source, or serve would rebuild on its own writes\. Use a folder directly under \1 whose name starts with _site, _serve, _pdf, or one inside such a folder, or one outside \1\.\n$/ },
+];
+
+// Every tool prints its usage on stdout and exits 0 for
+// --help and for -h, so each is a case, the two forms alike, unless the table
+// above already holds it. The value is the start of the tool's text where that
+// is not `usage: node <tool>`: an older text that opens otherwise, or one that
+// names the tool without its folder.
+// biome-ignore format: a table, one entry per line
+const HELP_TOOLS = {
+  "builder/tbdocs.mjs": null,
+  "book/render-book.mjs": "usage: node render-book.mjs <input.html> ",
+  "wisdom/wisdom.mjs": "Usage: node wisdom/wisdom.mjs <command> [options]\n",
+  "eval/build_corpus.mjs": "Usage: node eval/build_corpus.mjs ",
+  "eval/nav_hops.mjs": "Usage: node eval/nav_hops.mjs ",
+  "eval/run_case.mjs": "Usage: node eval/run_case.mjs ",
+  "eval/search_quality.mjs": "Usage: node eval/search_quality.mjs ",
+  "eval/site_search.mjs": "Usage: node eval/site_search.mjs ",
+  "eval/transcript.mjs": "Usage: node eval/transcript.mjs ",
+  "scripts/addin_test.mjs": null,
+  "scripts/ide_test.mjs": null,
+  "scripts/build_dot_metrics.mjs": null,
+  "scripts/build_package_api.mjs": null,
+  "scripts/census_attributes.mjs": null,
+  "scripts/check_a11y.mjs": null,
+  "scripts/check_a11y_fingerprint.mjs": null,
+  "scripts/check_axe_patch_equiv.mjs": null,
+  "scripts/check_attribute_sweep.mjs": null,
+  "scripts/check_book_coverage.mjs": null,
+  "scripts/check_ci_workflows.mjs": null,
+  "scripts/check_cli.mjs": null,
+  "scripts/check_code_regions.mjs": null,
+  "scripts/check_dot_fit.mjs": null,
+  "scripts/check_examples.mjs": null,
+  "scripts/check_gate_lists.mjs": null,
+  "scripts/check_impexp_parity.mjs": null,
+  "scripts/check_links.mjs": "Usage: node check_links.mjs [options] <inputs...>\n",
+  "scripts/check_links_diff.mjs": "Usage: node scripts/check_links_diff.mjs [options]\n",
+  "scripts/check_lint.mjs": null,
+  "scripts/check_page_baseline.mjs": null,
+  "scripts/check_pdf_shims_equiv.mjs": null,
+  "scripts/check_publish_policy.mjs": null,
+  "scripts/check_regex_safety.mjs": null,
+  "scripts/check_symbol_index.mjs": null,
+  "scripts/check_tb_registry.mjs": null,
+  "scripts/check_tree_fresh.mjs": null,
+  "scripts/check_twin_parsers.mjs": null,
+  "scripts/compare_trees.mjs": null,
+  "scripts/convert_em_dash_separators.mjs": null,
+  "scripts/crawl_check.mjs": null,
+  "scripts/gen_attribute_probes.mjs": "Generate a twinBASIC probe project for Reference/Attributes.md applicability.\n",
+  "scripts/impexp.mjs": "Usage:\n",
+  "scripts/pick_a11y_sample.mjs": null,
+  "scripts/survey_tooling.mjs": null,
+  "scripts/sweep_a11y.mjs": null,
+  "scripts/sweep_attributes.mjs": null,
+  "scripts/tbbuild.mjs": null,
+  "scripts/tbrun.mjs": null,
+};
+const literal = (text) => text.replace(/[.*+?^${}()|[\]\\/]/g, "\\$&");
+for (const [tool, start] of Object.entries(HELP_TOOLS)) {
+  const opening = start ? literal(start) : `${literal(`usage: node ${tool}`)}[ \\n]`;
+  for (const flag of ["--help", "-h"]) {
+    if (CASES.some((c) => c.tool === tool && c.args.length === 1 && c.args[0] === flag)) continue;
+    CASES.push({ tool, args: [flag], exit: 0, stdout: new RegExp(`^${opening}`) });
+  }
+  if (tool === "scripts/impexp.mjs") continue;
+  CASES.find((c) => c.tool === tool && c.args.length === 1 && c.args[0] === "--help").exitCodes = true;
+}
+
+// Every tool refuses an unknown flag and an empty value at
+// the parse, so each has a case for the first and, where it has a value
+// option, for the second: `tool: [option, extras]`, the option given as
+// `--option=`. Both exit 2, print the refusal on
+// stderr and nothing on stdout. `prefix` is the text a tool puts before its
+// message. `args` replaces `--bogus` where the tool must never get further than
+// the parse: convert_em_dash_separators would rewrite docs/ but for --check, and
+// wisdom needs a command that is not a real one. A case the table above already
+// holds, the same tool with the same arguments, is not added again.
+// biome-ignore format: a table, one entry per line
+const REFUSALS = {
+  "builder/tbdocs.mjs": ["src"],
+  "book/render-book.mjs": ["output"],
+  "wisdom/wisdom.mjs": ["guild", { args: ["bogus", "--bogus"], empty: ["bogus", "--guild="] }],
+  "eval/build_corpus.mjs": ["dest"],
+  "eval/nav_hops.mjs": ["from"],
+  "eval/run_case.mjs": ["corpus"],
+  "eval/search_quality.mjs": ["site"],
+  "eval/site_search.mjs": ["site"],
+  "eval/transcript.mjs": [null],
+  "scripts/addin_test.mjs": ["ide"],
+  "scripts/ide_test.mjs": ["ide"],
+  "scripts/build_dot_metrics.mjs": [null],
+  "scripts/build_package_api.mjs": ["out"],
+  "scripts/census_attributes.mjs": ["out"],
+  "scripts/check_a11y.mjs": ["root-dir"],
+  "scripts/check_a11y_fingerprint.mjs": ["pages"],
+  "scripts/check_axe_patch_equiv.mjs": ["patch"],
+  "scripts/check_attribute_sweep.mjs": [null],
+  "scripts/check_book_coverage.mjs": [null],
+  "scripts/check_ci_workflows.mjs": [null],
+  "scripts/check_cli.mjs": [null],
+  "scripts/check_code_regions.mjs": [null],
+  "scripts/check_dot_fit.mjs": [null],
+  "scripts/check_examples.mjs": ["only", { prefix: "check_examples: " }],
+  "scripts/check_gate_lists.mjs": [null],
+  "scripts/check_impexp_parity.mjs": [null],
+  "scripts/check_links.mjs": ["root-dir", { prefix: "error: " }],
+  "scripts/check_links_diff.mjs": ["a"],
+  "scripts/check_lint.mjs": [null, { prefix: "check_lint: " }],
+  "scripts/check_page_baseline.mjs": [null],
+  "scripts/check_pdf_shims_equiv.mjs": [null],
+  "scripts/check_publish_policy.mjs": ["src"],
+  "scripts/check_regex_safety.mjs": [null],
+  "scripts/check_symbol_index.mjs": [null],
+  "scripts/check_tb_registry.mjs": [null],
+  "scripts/check_tree_fresh.mjs": ["tree"],
+  "scripts/check_twin_parsers.mjs": [null],
+  "scripts/compare_trees.mjs": ["before", { prefix: "compare_trees: " }],
+  "scripts/convert_em_dash_separators.mjs": [null, { args: ["--check", "--bogus"] }],
+  "scripts/crawl_check.mjs": ["timeout"],
+  "scripts/gen_attribute_probes.mjs": [null],
+  "scripts/impexp.mjs": [null, { prefix: "ERROR: " }],
+  "scripts/pick_a11y_sample.mjs": ["sweep"],
+  "scripts/survey_tooling.mjs": ["root"],
+  "scripts/sweep_a11y.mjs": ["out"],
+  "scripts/sweep_attributes.mjs": ["out"],
+  "scripts/tbbuild.mjs": ["ide"],
+  "scripts/tbrun.mjs": ["ide"],
+};
+// The cases whose folder must stay empty, as for a help request: a refusal
+// starts no IDE or browser and writes nothing, and a tool that read the flag as
+// a folder name would create one.
+const LEAVES_EMPTY = new Set();
+for (const tool of Object.keys(HELP_TOOLS)) {
+  if (!(tool in REFUSALS)) throw new Error(`HELP_TOOLS names ${tool}, which REFUSALS does not`);
+}
+for (const [tool, [option, { exit = 2, prefix = "", args, empty } = {}]] of Object.entries(REFUSALS)) {
+  if (!(tool in HELP_TOOLS)) throw new Error(`REFUSALS names ${tool}, which HELP_TOOLS does not`);
+  const wanted = [
+    { args: args ?? ["--bogus"], stderr: new RegExp(`^${literal(`${prefix}unknown option: --bogus\n`)}`) },
+  ];
+  if (option)
+    wanted.push({
+      args: empty ?? [`--${option}=`],
+      stderr: new RegExp(`^${literal(`${prefix}--${option} needs a non-empty value\n`)}`),
+    });
+  for (const w of wanted) {
+    const held = CASES.find(
+      (c) => c.tool === tool && c.args.length === w.args.length && c.args.every((a, i) => a === w.args[i]),
+    );
+    if (held) LEAVES_EMPTY.add(held);
+    else {
+      const made = { tool, args: w.args, exit, stderr: w.stderr };
+      CASES.push(made);
+      LEAVES_EMPTY.add(made);
+    }
+  }
+}
+
+// A value a tool reads after the parse is checked straight after it: a number,
+// a regular expression, a URL, a date, a choice, an option that excludes
+// another. Each of these is refused before the tool starts anything, so the
+// case leaves its folder empty. `bad` is the message; a tool that prints its
+// usage after it is matched by the message and the opening of that usage. The
+// value that shows each rule is the one given: a word, 0, a fraction, a value
+// past the largest allowed, or `--x=-1`, the form that reaches the check (a
+// separate -1 is refused by the parse as a missing value).
+const BAD_VALUES = [];
+const bad = (tool, args, stderr, exit = 2) => BAD_VALUES.push({ tool, args, exit, stderr });
+// The message, then the opening of the tool's usage; `blank` when the tool puts
+// an empty line between them.
+const thenUsage = (message, tool, blank = false) =>
+  new RegExp(`^${literal(message)}\\n${blank ? "\\n" : ""}usage: node ${literal(tool)} `);
+const NOT_PORT = (v) => `--port expects a whole number from 1 to 65535, got: ${v}`;
+const NOT_COUNT = (option, v) => `${option} expects a whole number of at least 1, got: ${v}`;
+const NOT_WHOLE = (option, v) => `${option} expects a whole number of at least 0, got: ${v}`;
+const NOT_ABOVE_ZERO = (option, v) => `${option} expects a number greater than 0, got: ${v}`;
+const NOT_URL = (option, v) => `${option} expects an absolute http or https URL, got: ${v}`;
+const START = "http://127.0.0.1:9/";
+const REGEX_REASON = (option, v) =>
+  new RegExp(`^${literal(`${option} expects a regular expression, got: ${v} (`)}.+\\)\\n$`);
+
+// tbdocs prints the message alone, check_links after `error: `.
+bad("builder/tbdocs.mjs", ["--url", "foo"], NOT_URL("--url", "foo") + "\n");
+bad("builder/tbdocs.mjs", ["--url=mailto:x"], NOT_URL("--url", "mailto:x") + "\n");
+bad("builder/tbdocs.mjs", ["--stall-timeout", "abc"], "--stall-timeout expects a number of at least 0, got: abc\n");
+bad(
+  "scripts/check_links.mjs",
+  ["--offline", "--oracle", "x", "no-such-tree"],
+  "error: --oracle expects fs or index, got: x\n",
+);
+bad("scripts/check_links.mjs", ["--offline", "--oracle=", "no-such-tree"], "error: --oracle needs a non-empty value\n");
+
+// tbbuild and tbrun follow the message with their usage.
+for (const [tool, first] of [
+  ["scripts/tbbuild.mjs", "x.twinproj"],
+  ["scripts/tbrun.mjs", "no-such-dir"],
+]) {
+  bad(tool, [first, "--port", "0"], thenUsage(NOT_PORT(0), tool));
+  bad(tool, [first, "--port=65536"], thenUsage(NOT_PORT(65536), tool));
+  bad(tool, [first, "--port", "abc"], thenUsage(NOT_PORT("abc"), tool));
+  bad(tool, [first, "--timeout", "0"], thenUsage(NOT_ABOVE_ZERO("--timeout", 0), tool));
+  bad(tool, [first, "--timeout=-1"], thenUsage(NOT_ABOVE_ZERO("--timeout", -1), tool));
+  bad(tool, [first, "--arch", "WIN32"], thenUsage("--arch expects win32 or win64, got: WIN32", tool));
+  bad(tool, [first, "--show", "--hide"], thenUsage("--show and --hide cannot be given together", tool));
+}
+bad("scripts/tbrun.mjs", ["no-such-dir", "--quiet=-1"], thenUsage(NOT_WHOLE("--quiet", -1), "scripts/tbrun.mjs"));
+
+// sweep_attributes reads its values before it looks for an IDE, and follows the
+// message with its usage.
+{
+  const tool = "scripts/sweep_attributes.mjs";
+  bad(tool, ["--jobs", "0"], thenUsage(NOT_COUNT("--jobs", 0), tool));
+  bad(tool, ["--port", "0"], thenUsage(NOT_PORT(0), tool));
+  bad(tool, ["--port=65536"], thenUsage(NOT_PORT(65536), tool));
+  bad(tool, ["--port", "65535", "--jobs", "2"], thenUsage("--port 65535 with --jobs 2 runs past port 65535", tool));
+  bad(tool, ["--batch-size", "3"], thenUsage("--batch-size expects a whole number of at least 4, got: 3", tool));
+  bad(tool, ["--verify=-1"], thenUsage(NOT_WHOLE("--verify", -1), tool));
+  bad(tool, ["--timeout", "0"], thenUsage(NOT_ABOVE_ZERO("--timeout", 0), tool));
+  bad(tool, ["--forms", "some"], thenUsage("--forms expects bare, smart or all, got: some", tool));
+  bad(tool, ["--sites", "NO_SUCH_SITE"], thenUsage("unknown site: NO_SUCH_SITE (--list-sites names them)", tool));
+  // The drive root is outside the temp folder however the case is run; a relative name would resolve
+  // under it, where the case runs.
+  bad(tool, ["--work=/"], new RegExp(`^--work must be under .+, not .+\\nusage: node ${literal(tool)} `));
+  bad(tool, ["--show", "--hide"], thenUsage("--show and --hide cannot be given together", tool));
+}
+bad("scripts/tbrun.mjs", ["no-such-dir", "--quiet", "1.5"], thenUsage(NOT_WHOLE("--quiet", 1.5), "scripts/tbrun.mjs"));
+
+bad("scripts/addin_test.mjs", ["--only", "("], REGEX_REASON("--only", "("));
+bad("scripts/addin_test.mjs", ["--port", "0"], NOT_PORT(0) + "\n");
+bad("scripts/addin_test.mjs", ["--port=1.5"], NOT_PORT(1.5) + "\n");
+bad("scripts/addin_test.mjs", ["--jobs", "0"], NOT_COUNT("--jobs", 0) + "\n");
+bad("scripts/addin_test.mjs", ["--jobs=1.5"], NOT_COUNT("--jobs", 1.5) + "\n");
+bad(
+  "scripts/addin_test.mjs",
+  ["--timeout", "0"],
+  "--timeout expects a number greater than 0 and at most 2147483, got: 0\n",
+);
+bad(
+  "scripts/addin_test.mjs",
+  ["--timeout", "2147484"],
+  "--timeout expects a number greater than 0 and at most 2147483, got: 2147484\n",
+);
+bad("scripts/addin_test.mjs", ["--show", "--hide"], "--show and --hide cannot be given together\n");
+
+bad("scripts/ide_test.mjs", ["--only", "("], REGEX_REASON("--only", "("));
+bad("scripts/ide_test.mjs", ["--port", "0"], NOT_PORT(0) + "\n");
+bad("scripts/ide_test.mjs", ["--port=1.5"], NOT_PORT(1.5) + "\n");
+bad("scripts/ide_test.mjs", ["--jobs", "0"], NOT_COUNT("--jobs", 0) + "\n");
+bad("scripts/ide_test.mjs", ["--jobs=1.5"], NOT_COUNT("--jobs", 1.5) + "\n");
+bad(
+  "scripts/ide_test.mjs",
+  ["--timeout", "0"],
+  "--timeout expects a number greater than 0 and at most 2147483, got: 0\n",
+);
+bad(
+  "scripts/ide_test.mjs",
+  ["--timeout", "2147484"],
+  "--timeout expects a number greater than 0 and at most 2147483, got: 2147484\n",
+);
+bad("scripts/ide_test.mjs", ["--show", "--hide"], "--show and --hide cannot be given together\n");
+
+// check_examples prints "check_examples: " before the message.
+{
+  const tool = "scripts/check_examples.mjs";
+  const say = (message) => `check_examples: ${message}\n`;
+  bad(tool, ["--jobs", "abc"], say(NOT_COUNT("--jobs", "abc")));
+  bad(tool, ["--batch", "0"], say(NOT_COUNT("--batch", 0)));
+  bad(tool, ["--port", "0"], say(NOT_PORT(0)));
+  bad(tool, ["--port=65536"], say(NOT_PORT(65536)));
+  bad(
+    tool,
+    ["--only", "("],
+    new RegExp(`^check_examples: ${literal("--only expects a regular expression, got: ( (")}.+\\)\\n$`),
+  );
+  bad(tool, ["--apply"], say("--apply needs --propose"));
+  bad(tool, ["--apply", "--census"], say("--apply needs --propose"));
+  bad(tool, ["--census", "--propose"], say("--census and --propose cannot be given together"));
+  bad(tool, ["--report", "survey.json", "--census"], say("--report and --census cannot be given together"));
+  bad(
+    tool,
+    ["--report", "survey.json", "--census", "--propose"],
+    say("--report, --census and --propose cannot be given together"),
+  );
+  bad(tool, ["--show", "--hide"], say("--show and --hide cannot be given together"));
+}
+
+bad(
+  "scripts/survey_tooling.mjs",
+  ["--window", "abc"],
+  thenUsage(NOT_COUNT("--window", "abc"), "scripts/survey_tooling.mjs"),
+);
+bad("scripts/survey_tooling.mjs", ["--top=-1"], thenUsage(NOT_COUNT("--top", -1), "scripts/survey_tooling.mjs"));
+bad(
+  "scripts/compare_trees.mjs",
+  ["--max=-1"],
+  thenUsage(`compare_trees: ${NOT_WHOLE("--max", -1)}`, "scripts/compare_trees.mjs", true),
+);
+bad(
+  "scripts/compare_trees.mjs",
+  ["--max", "abc"],
+  thenUsage(`compare_trees: ${NOT_WHOLE("--max", "abc")}`, "scripts/compare_trees.mjs", true),
+);
+
+{
+  const tool = "scripts/crawl_check.mjs";
+  bad(tool, ["--concurrency", "0", START], thenUsage(NOT_COUNT("--concurrency", 0), tool));
+  bad(tool, ["--concurrency=1.5", START], thenUsage(NOT_COUNT("--concurrency", 1.5), tool));
+  bad(
+    tool,
+    ["--timeout", "0", START],
+    thenUsage("--timeout expects a whole number from 1 to 2147483647, got: 0", tool),
+  );
+  bad(
+    tool,
+    ["--timeout", "2147483648", START],
+    thenUsage("--timeout expects a whole number from 1 to 2147483647, got: 2147483648", tool),
+  );
+  bad(
+    tool,
+    ["--timeout", "abc", START],
+    thenUsage("--timeout expects a whole number from 1 to 2147483647, got: abc", tool),
+  );
+  bad(tool, ["foo"], thenUsage(NOT_URL("<start-url>", "foo"), tool));
+  bad(tool, ["mailto:x"], thenUsage(NOT_URL("<start-url>", "mailto:x"), tool));
+}
+
+bad("scripts/sweep_a11y.mjs", ["--limit", "0"], NOT_COUNT("--limit", 0) + "\n");
+bad("scripts/sweep_a11y.mjs", ["--limit=1.5"], NOT_COUNT("--limit", 1.5) + "\n");
+bad("scripts/sweep_a11y.mjs", ["--recycle-every", "0"], NOT_COUNT("--recycle-every", 0) + "\n");
+bad("scripts/sweep_a11y.mjs", ["--recycle-every", "abc"], NOT_COUNT("--recycle-every", "abc") + "\n");
+bad("scripts/pick_a11y_sample.mjs", ["--budget", "0"], NOT_ABOVE_ZERO("--budget", 0) + "\n");
+bad("scripts/pick_a11y_sample.mjs", ["--budget=-1"], NOT_ABOVE_ZERO("--budget", -1) + "\n");
+bad("scripts/pick_a11y_sample.mjs", ["--check", "--propose"], "--check and --propose cannot be given together\n");
+bad("scripts/pick_a11y_sample.mjs", ["--propose", "--census"], "--propose and --census cannot be given together\n");
+bad(
+  "scripts/pick_a11y_sample.mjs",
+  ["--check", "--propose", "--census"],
+  "--check, --propose and --census cannot be given together\n",
+);
+bad("scripts/check_a11y_fingerprint.mjs", ["--baseline", "nope"], /^--baseline expects production, .+, got: nope\n$/);
+bad("scripts/check_a11y_fingerprint.mjs", ["--candidate", "nope"], /^--candidate expects production, .+, got: nope\n$/);
+bad("scripts/check_a11y_fingerprint.mjs", ["--patches", "nope"], /^--patches expects .+, got: nope\n$/);
+bad("scripts/check_a11y_fingerprint.mjs", ["--patches=plain-color-fields,nope"], /^--patches expects .+, got: nope\n$/);
+bad("scripts/check_axe_patch_equiv.mjs", ["--patch", "nope"], /^--patch expects .+, got: nope\n$/);
+bad("scripts/check_links_diff.mjs", ["--max-lines", "abc"], NOT_WHOLE("--max-lines", "abc") + "\n");
+bad("scripts/check_links_diff.mjs", ["--max-lines=-1"], NOT_WHOLE("--max-lines", -1) + "\n");
+bad("scripts/check_links_diff.mjs", ["--max-lines=1.5"], NOT_WHOLE("--max-lines", 1.5) + "\n");
+
+const NOT_MS = (v) => `--timeout expects a whole number from 0 to 2147483647, got: ${v}\n`;
+bad("book/render-book.mjs", ["a.html", "-o", "out.pdf", "--timeout=-1"], NOT_MS(-1));
+bad("book/render-book.mjs", ["a.html", "-o", "out.pdf", "-t", "1.5"], NOT_MS(1.5));
+bad("book/render-book.mjs", ["a.html", "-o", "out.pdf", "-t", "2147483648"], NOT_MS(2147483648));
+
+bad("eval/run_case.mjs", ["--timeout", "0"], "--timeout expects a number greater than 0 and at most 35791, got: 0\n");
+bad(
+  "eval/run_case.mjs",
+  ["--timeout", "35792"],
+  "--timeout expects a number greater than 0 and at most 35791, got: 35792\n",
+);
+bad("eval/run_case.mjs", ["--protocol", "x"], "--protocol expects repo or site, got: x\n");
+bad("eval/search_quality.mjs", ["--sample", "0"], NOT_COUNT("--sample", 0) + "\n");
+bad("eval/search_quality.mjs", ["--worst=-1"], NOT_WHOLE("--worst", -1) + "\n");
+bad("eval/search_quality.mjs", ["--worst", "abc"], NOT_WHOLE("--worst", "abc") + "\n");
+bad("eval/search_quality.mjs", ["--failures=1.5"], NOT_WHOLE("--failures", 1.5) + "\n");
+bad("eval/site_search.mjs", ["--n", "0", "term"], NOT_COUNT("--n", 0) + "\n");
+bad("eval/site_search.mjs", ["--n=1.5", "term"], NOT_COUNT("--n", 1.5) + "\n");
+bad("eval/site_search.mjs", ["--composition", "term"], "--composition takes no search terms\n");
+bad("eval/nav_hops.mjs", ["("], REGEX_REASON("<url-regex>", "("));
+bad("eval/nav_hops.mjs", ["Reference", "[a-"], REGEX_REASON("<url-regex>", "[a-"));
+
+// build_corpus empties its --dest before it writes, so it refuses one that is or
+// contains the repository root, the folder it runs from or --repo, checked in
+// that order. Every one of these stops at the command line. Each --dest is a
+// folder that must never be emptied.
+{
+  const tool = "eval/build_corpus.mjs";
+  const refuse = (dest, what) =>
+    new RegExp(`^refusing --dest ${dest}: it is or contains ${what}, which cleaning it would delete\\n$`);
+  const docs = path.join(REPO_ROOT, "docs");
+  bad(tool, ["--dest", REPO_ROOT], refuse(literal(REPO_ROOT), "the repository root"));
+  bad(tool, ["--dest", path.dirname(REPO_ROOT)], refuse(literal(path.dirname(REPO_ROOT)), "the repository root"));
+  bad(tool, ["--dest", "."], refuse(".+", "the current folder"));
+  bad(tool, ["--dest", ".."], refuse(".+", "the current folder"));
+  bad(
+    tool,
+    ["--repo", path.join(docs, "Reference"), "--dest", docs],
+    refuse(literal(docs), literal(`--repo ${path.join(docs, "Reference")}`)),
+  );
+  bad(tool, ["--repo", docs, "--dest", docs], refuse(literal(docs), literal(`--repo ${docs}`)));
+}
+
+// wisdom's command in these is never a real one, so that none can start an
+// export, except extract, whose modes are refused before it reads a thing.
+{
+  const tool = "wisdom/wisdom.mjs";
+  const since = (v) => `--since expects an ISO 8601 date (YYYY-MM-DD) no earlier than 2015-01-01, got: ${v}\n`;
+  bad(tool, ["bogus", "--concurrency", "0"], NOT_COUNT("--concurrency", 0) + "\n");
+  bad(tool, ["bogus", "--concurrency=1.5"], NOT_COUNT("--concurrency", 1.5) + "\n");
+  bad(tool, ["bogus", "--cap=-1"], NOT_COUNT("--cap", -1) + "\n");
+  bad(tool, ["bogus", "--cap", "abc"], NOT_COUNT("--cap", "abc") + "\n");
+  bad(tool, ["bogus", "--rate-limit", "0"], NOT_ABOVE_ZERO("--rate-limit", 0) + "\n");
+  bad(tool, ["bogus", "--rate-limit", "abc"], NOT_ABOVE_ZERO("--rate-limit", "abc") + "\n");
+  bad(tool, ["bogus", "--since", "12"], since("12"));
+  bad(tool, ["bogus", "--since", "2024-02-30"], since("2024-02-30"));
+  bad(tool, ["bogus", "--since", "2014-12-31"], since("2014-12-31"));
+  bad(tool, ["bogus", "--min-confidence", "x"], "--min-confidence expects high, medium or low, got: x\n");
+  bad(tool, ["extract", "--all", "--force"], "--all and --force cannot be given together\n");
+  bad(tool, ["extract", "--since", "2024-01-01", "--force"], "--since and --force cannot be given together\n");
+  bad(
+    tool,
+    ["extract", "--since", "2024-01-01", "--all", "--force"],
+    "--since, --all and --force cannot be given together\n",
+  );
+}
+for (const made of BAD_VALUES) {
+  CASES.push(made);
+  LEAVES_EMPTY.add(made);
+}
+
+export { CASES, LEAVES_EMPTY };

From 7d7e72cb1f3c3daf081d912cc4e2814c9a5fde52 Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 13:28:55 +0200
Subject: [PATCH 09/22] lint: noUndeclaredVariables on, with axe and Paged
 declared only where they run in a page

---
 biome.jsonc                 | 16 +++++++++++++++-
 docs/Documentation/Tools.md |  2 +-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/biome.jsonc b/biome.jsonc
index 899798cc..999d6075 100644
--- a/biome.jsonc
+++ b/biome.jsonc
@@ -51,7 +51,10 @@
     "enabled": true,
     "rules": {
       "preset": "none",
-      "correctness": { "preset": "recommended" },
+      // A name a module uses but never declares or imports. Off in the
+      // recommended set; a function moved to a module of its own without its
+      // imports passed every gate until the script ran.
+      "correctness": { "preset": "recommended", "noUndeclaredVariables": "error" },
       "suspicious": {
         "preset": "recommended",
         // `while ((m = re.exec(s)))` is how this tree walks a regex's matches.
@@ -63,6 +66,17 @@
     }
   },
   "overrides": [
+    {
+      // Functions these hand to puppeteer's page.evaluate run in the page,
+      // after axe-core has been injected into it as the global `axe`.
+      "includes": ["scripts/lib/axe-scan.mjs", "scripts/check_axe_patch_equiv.mjs"],
+      "javascript": { "globals": ["axe"] }
+    },
+    {
+      // Loaded into the book's page by pagedjs, which defines `Paged`.
+      "includes": ["book/lib/progress-handler.js"],
+      "javascript": { "globals": ["Paged"] }
+    },
     {
       // ES5-style scripts that ship to readers as written.
       // A trailing comma after a call's last argument is ES2017.
diff --git a/docs/Documentation/Tools.md b/docs/Documentation/Tools.md
index de497111..f5a20789 100644
--- a/docs/Documentation/Tools.md
+++ b/docs/Documentation/Tools.md
@@ -540,7 +540,7 @@ Exit codes: **0** both workflows run every gate the wrappers run, and its own pr
     node scripts/check_lint.mjs
     node scripts/check_lint.mjs --staged
 
-Runs Biome, pinned to an exact version, over the tooling: `builder/`, `scripts/`, `lib/`, `book/`, `eval/`, `wisdom/`, `test/` and the site's two scripts in `docs/assets/js/`, less the exceptions that `biome.jsonc` at the repository root lists and explains. It runs `biome check`, which lints and checks formatting in one pass. The lint rules are the ones that find defects --- Biome's correctness and suspicious groups --- and none about style; the configuration names the few it turns off, each with its reason. Moving and deleting code leaves unused imports and undeclared names behind, and nothing else reads the tooling for them. Style belongs to the formatter, whose settings are in the same file: a file it would change is a finding, and `npx biome format --write` fixes it. A literal table laid out by hand keeps its layout under a `// biome-ignore format:` comment with a reason. No browser, no built tree, a fraction of a second.
+Runs Biome, pinned to an exact version, over the tooling: `builder/`, `scripts/`, `lib/`, `book/`, `eval/`, `wisdom/`, `test/` and the site's two scripts in `docs/assets/js/`, less the exceptions that `biome.jsonc` at the repository root lists and explains. It runs `biome check`, which lints and checks formatting in one pass. The lint rules are the ones that find defects --- Biome's correctness and suspicious groups --- and none about style; the configuration names the few it turns off and the one it adds, `noUndeclaredVariables`, each with its reason, and declares the page globals --- `axe`, `Paged` --- only for the files whose code runs in that page. Moving and deleting code leaves unused imports and undeclared names behind, and nothing else reads the tooling for them. Style belongs to the formatter, whose settings are in the same file: a file it would change is a finding, and `npx biome format --write` fixes it. A literal table laid out by hand keeps its layout under a `// biome-ignore format:` comment with a reason. No browser, no built tree, a fraction of a second.
 
 **Warnings fail as well as errors.** Biome reports an unused import or variable as a warning, and exits 0 on warnings, so a plain `npx biome lint` passes a file full of them. The gate also refuses to pass when Biome could not lint. Biome exits 1 for a broken `biome.jsonc`, as it does for a finding, and 0 for a scope that matches no script at all, so the gate reads the summary Biome writes beside its usual output to tell these apart.
 

From 964f06118d2f9588a7d2cc0e7baabc392ba54e8c Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 13:44:53 +0200
Subject: [PATCH 10/22] bugs: the command-line entries re-run on BETA 995,
 unchanged

---
 BUGS-TO-REPORT.md | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/BUGS-TO-REPORT.md b/BUGS-TO-REPORT.md
index 01502aad..57e212ee 100644
--- a/BUGS-TO-REPORT.md
+++ b/BUGS-TO-REPORT.md
@@ -21,7 +21,7 @@ What an entry owes a reader:
 
 ## The recent-projects list fills its empty slots with copies of its last entry
 
-**Build:** BETA 983
+**Build:** BETA 995
 **Severity:** cosmetic, but it shows on a new installation, which is exactly when the
 list has empty slots --- the same project repeated down the Recent tab.
 
@@ -134,7 +134,7 @@ candidate, and the interface cycle compiled instead of crashing.
 
 ## `--buildAndExit32` writes nothing, exits 0 on a project with errors, and hangs on a failing build
 
-**Build:** BETA 983
+**Build:** BETA 995; the silence on stdout and stderr was measured on BETA 983
 **Severity:** makes the documented unattended-build switch unusable.
 
 The IDE executable accepts `--buildAndExit32` and `--buildAndExit64`; `parseCommandLine()`
@@ -343,7 +343,7 @@ member it implements, and its description of the attribute says why.
 
 ## `import` stops with exit code 999 on any folder inside `Packages`, so a project that embeds a package cannot be packed
 
-**Build:** BETA 983 --- `twinBASIC_win32.exe` and `twinBASIC_win64.exe` alike
+**Build:** BETA 995 --- `twinBASIC_win32.exe`; on BETA 983 `twinBASIC_win64.exe` as well
 **Severity:** the command line cannot pack any project that embeds a package, and the
 failure prints neither `... DONE` nor `... FAILED`.
 
@@ -401,7 +401,7 @@ included, which `export` does not write.
 
 ## `export` and `import` stop at the 260-character path limit, apart from the one path they prefix with `\\?\`
 
-**Build:** BETA 983 --- `twinBASIC_win32.exe`, on a machine with `LongPathsEnabled` set to 1
+**Build:** BETA 995 --- `twinBASIC_win32.exe`, on a machine with `LongPathsEnabled` set to 1
 **Severity:** an `export` to a deep folder writes part of the tree and exits 0, and the
 errors it prints blame permissions and storage space.
 
@@ -439,7 +439,8 @@ trees as complete.
 
 ## A damaged project file opens a message box, and the command waits until it is closed
 
-**Build:** BETA 983 --- `twinBASIC_win32.exe`
+**Build:** BETA 983 --- `twinBASIC_win32.exe`; not re-run on BETA 995, since the box opens
+on the desktop of whoever runs the command
 **Severity:** an unattended `export`, `settings` or `readme` never finishes; once the box is
 closed, `export` reports success.
 
@@ -471,7 +472,7 @@ known.
 
 ## `export` refused for lack of `--overwrite` still writes part of the tree
 
-**Build:** BETA 983
+**Build:** BETA 995
 **Severity:** a refused export leaves the folder a mixture of the old tree and the project.
 
 Export the HelloWorld sample into a folder, delete the exported `Settings`, edit
@@ -496,7 +497,7 @@ writes one copy and then refuses the other because of the file it has just writt
 
 ## The IDE has written the same name twice into project files it ships
 
-**Build:** BETA 983
+**Build:** BETA 995
 **Severity:** a folder can hold only one of them, so unpacking keeps one copy; which copy the
 IDE itself uses is not known.
 
@@ -520,7 +521,7 @@ the repeated entries in a warning.
 
 ## `export` needs a full, backslashed project path, and no folder path may use forward slashes
 
-**Build:** BETA 983
+**Build:** BETA 995
 **Severity:** ordinary relative and forward-slashed paths fail, with messages that say the
 file or folder does not exist.
 
@@ -541,7 +542,7 @@ creates every missing level of its output folder.
 
 ## `import` of a folder with no `Settings` file fails without saying why
 
-**Build:** BETA 983
+**Build:** BETA 995
 **Severity:** minor --- the refusal is right, and the silence is not.
 
 Given a folder with no `Settings` file at its top, `import` lists the files it read, ends

From 01338f432644a7a44da3e2c7b25b9868bb905049 Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 13:46:25 +0200
Subject: [PATCH 11/22] test: the export lane asserts ${SourcePath}'s deletion
 and the CLI's refusal to repack

---
 BUGS-TO-REPORT.md        | 11 +++++++----
 scripts/lib/tb-lane.mjs  |  8 ++++++--
 test/ide/export.test.mjs | 31 ++++++++++++++++++++++++++++++-
 3 files changed, 43 insertions(+), 7 deletions(-)

diff --git a/BUGS-TO-REPORT.md b/BUGS-TO-REPORT.md
index 57e212ee..177e854a 100644
--- a/BUGS-TO-REPORT.md
+++ b/BUGS-TO-REPORT.md
@@ -720,7 +720,7 @@ completely --- `.git` included, with no prompt.
 
 ## Export Path refuses `${SourcePath}` alone, but not the same folder written as a path
 
-**Build:** BETA 983
+**Build:** BETA 995
 **Severity:** the project file is deleted when the export folder is the folder that holds it.
 
 The Settings editor's check on `project.exportPath` in `ide/main.js` compares the text with
@@ -731,14 +731,17 @@ logged `[EXPORT]  DELETED: \\?\<folder>\<project>.twinproj` and completed. A **S
 wrote the file back; closing without saving loses it.
 
 **Found by** the same probe. The compiler's side was measured, by calling `exportProjectTo()`
-with the folder; that the editor accepts the same folder typed as a path is read from the
-check's code, not tried.
+with the folder, and `ide-test.bat`'s `export` lane asserts it; that the editor accepts the
+same folder typed as a path is read from the check's code, not tried. The Save that writes
+the file back was seen on BETA 983 only.
 
 ---
 
 ## Export Project writes the compiler packages, which the project does not hold, and the command line cannot pack the result
 
-**Build:** BETA 983
+**Build:** BETA 995 for the export and the command line's `import` of it, which
+`ide-test.bat`'s `export` lane asserts; the IDE's own import and the dead copy were measured
+on BETA 983
 **Severity:** the IDE's export of a project cannot be packed back into a project by the
 supported tool, so it cannot serve for version control; and a two-file project exports as
 477 files.
diff --git a/scripts/lib/tb-lane.mjs b/scripts/lib/tb-lane.mjs
index 062c1f2b..71252759 100644
--- a/scripts/lib/tb-lane.mjs
+++ b/scripts/lib/tb-lane.mjs
@@ -197,12 +197,16 @@ export class Lane {
    * @param {object} [o.env]      extra environment for the IDE, as launchIde takes it.
    *                              An add-in reads it with Environ$, since it runs in the
    *                              compiler's process, which the IDE starts (P10)
+   * @param {string} [o.folder]   the folder the .twinproj is staged in (default the work
+   *                              folder); give a folder of its own to a scenario that
+   *                              writes into the project's folder
    * @returns {Promise<object>} the connection (attachIde's), which the tb-operate.mjs calls take
    */
-  async open(src, { timeout = COMPILE_TIMEOUT, env = {} } = {}) {
+  async open(src, { timeout = COMPILE_TIMEOUT, env = {}, folder = this.work } = {}) {
     if (this.run) throw new Error(`lane ${this.name} has a project open already: one IDE at a time`);
     const exe = this.copy();
-    const project = path.join(this.work, "project.twinproj");
+    mkdirSync(folder, { recursive: true });
+    const project = path.join(folder, "project.twinproj");
     stageProject({
       src,
       stage: path.join(this.work, "project-src"),
diff --git a/test/ide/export.test.mjs b/test/ide/export.test.mjs
index 3d56617a..9d88c4ff 100644
--- a/test/ide/export.test.mjs
+++ b/test/ide/export.test.mjs
@@ -11,11 +11,13 @@
 // Run it with ide-test.bat, which gives it a lane; on its own it is skipped.
 
 import assert from "node:assert/strict";
+import { spawnSync } from "node:child_process";
 import { chmodSync, existsSync, mkdirSync, readdirSync, symlinkSync, writeFileSync } from "node:fs";
 import path from "node:path";
 import { before, test } from "node:test";
 import { fileURLToPath } from "node:url";
 import { consoleMark, linesSince } from "../../scripts/lib/tb-ide-console.mjs";
+import { compilerExe } from "../../scripts/lib/tb-install.mjs";
 import { messageBoxes, waitFor } from "../../scripts/lib/tb-operate.mjs";
 import { scenario } from "../addin/scenario.mjs";
 
@@ -52,9 +54,13 @@ scenario("Export Project", (lane) => {
     return lines;
   }
 
+  // The project's own folder, holding nothing but the .twinproj: the last test
+  // exports into it.
+  const projectDir = path.join(lane.work, "project");
+
   before(async () => {
     mkdirSync(root, { recursive: true });
-    c = await lane.open(PROJECT);
+    c = await lane.open(PROJECT, { folder: projectDir });
   });
 
   test("an export into an empty folder writes the compiler packages", async () => {
@@ -100,6 +106,29 @@ scenario("Export Project", (lane) => {
     assert.deepEqual(boxes, []);
   });
 
+  test("the command line's import refuses the IDE's export, for its compiler packages", () => {
+    const out = path.join(root, "plain");
+    const packed = path.join(root, "repacked.twinproj");
+    const r = spawnSync(compilerExe(lane.copy()), ["import", packed, `${out}\\`, "--overwrite"], {
+      encoding: "utf8",
+      stdio: ["ignore", "pipe", "pipe"],
+    });
+    assert.equal(r.status, 999);
+    assert.equal(existsSync(packed), false);
+  });
+
+  // Last, since it deletes the open project's file. The Settings editor refuses
+  // an Export Path of ${SourcePath} alone, but the compiler checks nothing.
+  test("an export into the project's own folder deletes the project file", async () => {
+    const lines = await exportTo(projectDir);
+    assert.ok(
+      lines.includes(`DELETED: \\\\?\\${lane.project}`),
+      "the export no longer deletes the project file in its folder",
+    );
+    assert.match(lines.at(-1), /^COMPLETED \(\d+ folders, \d+ files\)$/);
+    assert.equal(existsSync(lane.project), false);
+  });
+
   // The runner removes the work folder afterwards, and a read-only file would
   // stop it.
   return () => {

From c6193940aeeb7e04118749db16dcd619a4561fc0 Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 14:37:05 +0200
Subject: [PATCH 12/22] test: the packages lane asserts that one Apply keeps
 running the replaced package

---
 BUGS-TO-REPORT.md          |   3 +-
 test/ide/packages.test.mjs | 229 ++++++++++++++++++++++++++++++++++++-
 2 files changed, 229 insertions(+), 3 deletions(-)

diff --git a/BUGS-TO-REPORT.md b/BUGS-TO-REPORT.md
index 177e854a..ed3bce2c 100644
--- a/BUGS-TO-REPORT.md
+++ b/BUGS-TO-REPORT.md
@@ -959,7 +959,8 @@ the file's path in place of the native picker.
 
 ## Replacing an embedded package under one Apply keeps running the old copy
 
-**Build:** BETA 983
+**Build:** BETA 995, asserted by `ide-test.bat`'s `packages` lane with the two-Apply path as
+its control; the linked-copy rows below were measured on BETA 983
 **Severity:** the project builds and runs the old package after the user has replaced it.
 
 1. A project embeds a package built locally, `DocProbePkg` v1.
diff --git a/test/ide/packages.test.mjs b/test/ide/packages.test.mjs
index 903f8fbb..67c1d8b9 100644
--- a/test/ide/packages.test.mjs
+++ b/test/ide/packages.test.mjs
@@ -22,11 +22,13 @@
 
 import assert from "node:assert/strict";
 import { execFileSync } from "node:child_process";
-import { readFileSync } from "node:fs";
+import { cpSync, mkdirSync, readFileSync, writeFileSync } from "node:fs";
 import path from "node:path";
 import { before, test } from "node:test";
 import { fileURLToPath } from "node:url";
-import { click, waitFor } from "../../scripts/lib/tb-operate.mjs";
+import { waitForCompile } from "../../scripts/lib/tb-ide.mjs";
+import { consoleMark, linesSince } from "../../scripts/lib/tb-ide-console.mjs";
+import { click, clickAt, openFile, waitFor } from "../../scripts/lib/tb-operate.mjs";
 import { scenario } from "../addin/scenario.mjs";
 
 const HERE = path.dirname(fileURLToPath(import.meta.url));
@@ -107,3 +109,226 @@ scenario("Import from file... in the Packages dialog", (lane) => {
     assert.ok(!referenced.includes("DocProbePkg"), "the imported package is now ticked");
   });
 });
+
+// ---------------------------------------------------------------------------
+// Replacing an embedded package: BUGS-TO-REPORT.md, "Replacing an embedded
+// package under one Apply keeps running the old copy". The probe is a project
+// that embeds DocProbePkg v1 and prints what the package's function returns.
+// It replaces v1 with v2 (untick v1, import v2, tick v2) and runs again. The
+// control applies after the untick and again after the tick; the other test
+// applies once, at the end, and differs from the control in nothing else.
+//
+// Both versions are generated into the lane's work folder from the v1 tree at
+// probes/packages/DocProbePkg, which the first test above uses as it is. v2
+// has its version fields in Settings at 2.0.0.0 and its function returns 2.
+// Both also get the three empty folders every exported package has,
+// ImportedTypeLibraries, Miscellaneous and Packages: BETA 995's compiler dies
+// at start on a project that embeds a package without them, three times, and
+// the IDE then drops into Safe Mode, where nothing runs. (Measured with a copy
+// of the tree with and without the folders; which of the three it needs was not
+// narrowed.) Each test works on a copy of the host project in its own folder,
+// because applying writes the project's settings. The copy's Main is empty
+// until v1 is embedded, since the host cannot compile before the package is
+// referenced; the test then writes Main in the editor.
+
+const RUN_MAIN = `Module Startup
+    Public Sub Main()
+        Debug.Print "DocProbeVersion=" & DocProbeVersion()
+    End Sub
+End Module
+`;
+
+const VERSION_PREFIX = "DocProbeVersion=";
+
+// The three folders an exported package always has.
+const PACKAGE_FOLDERS = ["ImportedTypeLibraries", "Miscellaneous", "Packages"];
+
+// The References page's rows, for a failure message: the list each is in,
+// its name, and whether its tick box is ticked.
+const ROWS_JS = `[...document.querySelectorAll(".referencesListRow")].map((r) => ({
+  list: r.parentElement.className,
+  name: r.querySelector(".referencesListColName2, .referencesListColSymbol")?.textContent.trim() ?? "",
+  ticked: !!r.querySelector(".referencesListColEnabled .tickIcon2"),
+})).filter((r) => r.ticked || r.name.includes("DocProbe"))`;
+
+// The page's two lists of rows. Installed references are in the first, with
+// the name of the package followed by an edit mark; Available Packages are in
+// the second, named by their description, which here is the same text for v1
+// and v2.
+const INSTALLED = "referencesListNew";
+const AVAILABLE = "referencesListNewAvailable";
+const DESCRIPTION = "DocProbePkg.twinpack";
+
+scenario("Replacing an embedded package", (lane) => {
+  let c;
+  let v1;
+  let v2;
+  const sleep = (ms) => new Promise((r) => setTimeout(r, ms));
+
+  // A copy of the v1 tree in the work folder, with the empty folders, for
+  // `version`, packed to a .twinpack as the first test does.
+  function packVersion(version) {
+    const tree = path.join(lane.work, `DocProbePkg-v${version}`);
+    cpSync(PKG, tree, { recursive: true });
+    for (const folder of PACKAGE_FOLDERS) mkdirSync(path.join(tree, folder), { recursive: true });
+    const settings = path.join(tree, "Settings");
+    const source = path.join(tree, "Sources", "DocProbe.twin");
+    writeFileSync(
+      settings,
+      readFileSync(settings, "utf8").replace('"project.versionMajor": 1', `"project.versionMajor": ${version}`),
+    );
+    writeFileSync(source, readFileSync(source, "utf8").replace("Return 1", `Return ${version}`));
+    const out = `${tree}.twinpack`;
+    execFileSync(process.execPath, [path.join(REPO, "scripts", "impexp.mjs"), "import", out, tree], { stdio: "pipe" });
+    return out;
+  }
+
+  before(() => {
+    v1 = packVersion(1);
+    v2 = packVersion(2);
+  });
+
+  // Open the Settings editor on the References page, and wait for it to load.
+  async function openReferences() {
+    await c.evaluate(`executeIdeCommand("tbProject_ShowReferences"), null`);
+    assert.ok(await waitFor(c, (c) => c.evaluate(`!!${CONFIG_JS}`), { timeout: 20 * 1000 }), "no Settings editor");
+    assert.ok(
+      await waitFor(c, async () => (await c.evaluate(WAITING_JS)) === 0, { timeout: 60 * 1000 }),
+      "the References page never finished loading",
+    );
+  }
+
+  // Click the tick box of the row in `list` that names a package and is in
+  // the state `ticked`, with a real click, as a person does.
+  async function tick(name, { ticked, list }) {
+    const find = `(() => {
+      const r = [...document.querySelectorAll(".referencesListRow")].find((r) =>
+        r.querySelector(".referencesListColName2, .referencesListColSymbol")?.textContent.includes(${JSON.stringify(name)})
+        && r.parentElement.className === ${JSON.stringify(list)}
+        && !!r.querySelector(".referencesListColEnabled .tickIcon2") === ${ticked});
+      if (!r) return null;
+      const b = r.querySelector(".referencesListColEnabled");
+      b.scrollIntoView({ block: "center" });
+      const q = b.getBoundingClientRect();
+      return { x: q.x + q.width / 2, y: q.y + q.height / 2 };
+    })()`;
+    const where = await waitFor(c, (c) => c.evaluate(find), { timeout: 15 * 1000 });
+    assert.ok(
+      where,
+      `no ${ticked ? "ticked" : "unticked"} row for ${name} in ${list}: ${JSON.stringify(await c.evaluate(ROWS_JS))}`,
+    );
+    await clickAt(c, where.x, where.y);
+    await sleep(1500);
+  }
+
+  // Import a package through Available Packages, as the first test does.
+  async function importFile(file) {
+    await click(c, { css: "div", text: "Available Packages" });
+    await c.evaluate(stubsJs(file, readFileSync(file).toString("base64")));
+    await click(c, { css: "div", text: "Import from file..." });
+    const answers = await waitFor(c, async () => {
+      const a = await c.evaluate("window.__importAnswers");
+      return a.length ? a : null;
+    });
+    assert.ok(answers?.[0].success, "the compiler did not accept the import");
+  }
+
+  // Click Apply, #SAVEBTN, and wait for the compile to settle. Returns what the
+  // console showed: the restart, the save, or only "Project settings updated".
+  async function apply({ errors = false } = {}) {
+    const mark = await consoleMark(c);
+    await click(c, { css: "#SAVEBTN" });
+    assert.ok(
+      await waitFor(c, async () => !(await c.evaluate(`!!${CONFIG_JS}`)), { timeout: 20 * 1000 }),
+      "the Settings editor stayed open",
+    );
+    await sleep(2000);
+    await settle({ errors });
+    return linesSince(c, mark);
+  }
+
+  // Wait until the compiler has settled, with no errors unless `errors`: with
+  // the package unticked, Main no longer compiles.
+  async function settle({ errors = false } = {}) {
+    const waited = await waitForCompile(c, { project: lane.project, timeout: 90 * 1000 });
+    assert.ok(waited.loaded && !waited.crash, `the compiler did not settle: ${JSON.stringify(waited)}`);
+    if (!errors) assert.match(waited.last, /"e":"0"/, `the compile has errors: ${waited.last}`);
+  }
+
+  // Start a run from the editor, as F5 does, and read the version the host
+  // printed; end the run.
+  async function runVersion() {
+    const mark = await consoleMark(c);
+    await c.evaluate(`executeIdeCommand("tbDebug_StartOrContinue")`);
+    const lines = await waitFor(
+      c,
+      async () => {
+        const l = await linesSince(c, mark);
+        return l.some((x) => x.startsWith(VERSION_PREFIX)) ? l : null;
+      },
+      { timeout: 60 * 1000 },
+    );
+    assert.ok(lines, `the run printed no version: ${JSON.stringify(await linesSince(c, mark))}`);
+    await c.evaluate(`executeIdeCommand("tbDebug_Stop")`).catch(() => {});
+    return Number(lines.find((x) => x.startsWith(VERSION_PREFIX)).slice(VERSION_PREFIX.length));
+  }
+
+  // The entry's three steps on a project of its own, and what each Apply
+  // wrote to the console. `applyAfterUntick` is the control.
+  async function replace(name, applyAfterUntick) {
+    const host = path.join(lane.work, name);
+    cpSync(HOST, host, { recursive: true });
+    c = await lane.open(host, { folder: path.join(lane.work, `${name}-staged`) });
+    const applies = {};
+
+    // Step 1: embed v1: import it, tick it, one Apply.
+    await openReferences();
+    await importFile(v1);
+    await tick(DESCRIPTION, { ticked: false, list: AVAILABLE });
+    applies.embed = await apply();
+    await openFile(c, "/PackagesProbe/Sources/Startup.twin");
+    await c.evaluate(`editor.getModel().setValue(${JSON.stringify(RUN_MAIN)})`);
+    await sleep(3000);
+    await settle();
+    const first = await runVersion();
+
+    // Step 2: untick v1, import v2, tick v2.
+    await openReferences();
+    await tick("DocProbePkg", { ticked: true, list: INSTALLED });
+    if (applyAfterUntick) {
+      applies.untick = await apply({ errors: true });
+      await openReferences();
+    }
+    await importFile(v2);
+    await tick(DESCRIPTION, { ticked: false, list: AVAILABLE });
+    // Step 3: Apply.
+    applies.replace = await apply();
+    const second = await runVersion();
+    return { first, second, applies };
+  }
+
+  // What an Apply wrote to the console.
+  const restarted = (lines) => lines.some((l) => /restarting from FILE|require compiler-restart/.test(l));
+  const saved = (lines) => lines.some((l) => /saving to disk \[DONE\]/.test(l));
+
+  test("an Apply after the untick and another after the tick: each restarts and saves, and v2 runs (control)", async () => {
+    const r = await replace("control", true).finally(() => lane.closeProject());
+    assert.equal(r.first, 1, "v1 did not run");
+    for (const step of ["embed", "untick", "replace"]) {
+      assert.ok(restarted(r.applies[step]) && saved(r.applies[step]), `the ${step} Apply did not restart and save`);
+    }
+    assert.equal(r.second, 2, "v2 does not run after the second Apply");
+  });
+
+  // BETA 995, as BETA 983 by hand: the one Apply writes only the line "Project
+  // settings updated". The compiler is not restarted and nothing is saved, and
+  // the run still prints v1. The control above is what shows that the probe can
+  // tell the two versions apart.
+  test("one Apply after the untick, the import and the tick: no restart, no save, and v1 still runs", async () => {
+    const r = await replace("oneapply", false).finally(() => lane.closeProject());
+    assert.equal(r.first, 1, "v1 did not run");
+    assert.ok(restarted(r.applies.embed) && saved(r.applies.embed), "the embed Apply did not restart and save");
+    assert.deepEqual(r.applies.replace, ["[COMPILER] Project settings updated"]);
+    assert.equal(r.second, 1, "v2 runs after one Apply: the bug looks fixed, so update BUGS-TO-REPORT.md");
+  });
+});

From a490c28b48b92feac801a5ea437829f472935be1 Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 14:56:05 +0200
Subject: [PATCH 13/22] bugs: FastCall and ThisCall delegates call as stdcall
 on win32

---
 BUGS-TO-REPORT.md | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/BUGS-TO-REPORT.md b/BUGS-TO-REPORT.md
index ed3bce2c..a1e41994 100644
--- a/BUGS-TO-REPORT.md
+++ b/BUGS-TO-REPORT.md
@@ -980,6 +980,47 @@ and v2 runs at once.
 
 ---
 
+## A call through a `FastCall` or `ThisCall` delegate is made as stdcall on win32
+
+**Build:** BETA 995
+**Severity:** the delegate is unusable on win32; every call through it raises an error.
+
+```tb
+Public Delegate Function FastDel FastCall (ByVal a As Long, ByVal b As Long) As Long
+
+Public Function GF FastCall(ByVal a As Long, ByVal b As Long) As Long
+    Return a * 100 + b
+End Function
+
+Public Function GS(ByVal a As Long, ByVal b As Long) As Long
+    Return a * 100 + b
+End Function
+
+Dim d As FastDel = AddressOf GF
+Debug.Print d(9, 1)        ' error: "Bad DLL definition.  Stack corruption detected."
+Dim e As FastDel = AddressOf GS
+Debug.Print e(9, 1)        ' 901: a stdcall target works, after warning TB0026
+```
+
+The same with `ThisCall` in place of `FastCall`, for the delegate and the function, raises the
+same error. So the call through the delegate passes the arguments as stdcall does, whatever
+convention the delegate declares.
+
+**What does not reproduce it:**
+
+- calling `GF` directly: 901. The callee side is right: a `FastCall Naked` function that
+  returns `ECX + EDX`, and a `ThisCall Naked` one that returns `ECX + [ESP+4]` and ends
+  `ret 4`, return the right sums when called directly;
+- delegates declared stdcall (no keyword) or `CDecl`, each pointed at a function of its own
+  convention: 901;
+- a win64 build: every case above returns 901 (x64 has one calling convention).
+
+**Observed** with a `[RunAfterBuild]` probe through `tbrun`, and in the compiled EXE `tbrun`
+left, run from its `Sub Main` and writing to a file: the same five results both ways. Both
+keywords are new in BETA 990 and 992; BETA 987 refuses them (TB5182).
+
+---
+
 ## An error in the body of a generic procedure names neither the type nor the call that caused it
 
 **Build:** BETA 995

From c5636ac944503dc6f4dbfa1abcd7ebd06b2e2c59 Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 16:37:54 +0200
Subject: [PATCH 14/22] docs: ThisCall and FastCall, in API Declarations'
 Calling Conventions and the Core syntax lines

---
 docs/Features/Advanced/API-Declarations.md | 71 ++++++++++++++++++++--
 docs/Features/index.md                     |  2 +-
 docs/Reference/Core/AddressOf.md           |  2 +-
 docs/Reference/Core/Declare.md             | 11 ++--
 docs/Reference/Core/Delegate.md            |  9 +--
 docs/Reference/Core/Function.md            |  5 +-
 docs/Reference/Core/Interface.md           |  2 +-
 docs/Reference/Core/Sub.md                 |  5 +-
 docs/Reference/twinBASIC-Additions.md      |  4 +-
 docs/Tutorials/Windows-API.md              |  2 +-
 10 files changed, 93 insertions(+), 20 deletions(-)

diff --git a/docs/Features/Advanced/API-Declarations.md b/docs/Features/Advanced/API-Declarations.md
index 87b6883b..4be70fc6 100644
--- a/docs/Features/Advanced/API-Declarations.md
+++ b/docs/Features/Advanced/API-Declarations.md
@@ -23,16 +23,42 @@ Both represent a fully Unicode operation, but the allows direct use of the `Stri
 > [!WARNING]
 > This does **not** change the underlying data types-- the `String` type is a `BSTR`, not an `LPWSTR`, so in the event an API returns a pre-allocated `LPWSTR`, rather than filling a buffer you have created, it will not provide a valid `String` type. This would be the case where an API parameter is given as `[out] LPWSTR *arg`.
 
-## CDecl Support
+## Calling Conventions
 
-The cdecl calling convention is supported both for API declares and methods in your code. This includes DLL exports in standard DLLs.
+An API declaration, a procedure, a delegate or an interface member can name its calling convention. The keyword goes directly after the name. Without one, the convention is stdcall, as in VBA.
+
+| Keyword        | Convention | Arguments on win32                                  | Stack cleaned by |
+|----------------|------------|-----------------------------------------------------|------------------|
+| (none)         | stdcall    | all on the stack                                    | the callee       |
+| **CDecl**      | cdecl      | all on the stack                                    | the caller       |
+| **ThisCall**   | thiscall   | the first in the ECX register, the rest on the stack | the callee       |
+| **FastCall**   | fastcall   | the first two in ECX and EDX, the rest on the stack  | the callee       |
+
+The four follow the Microsoft C/C++ conventions of the same names: `__stdcall`, `__cdecl`, `__thiscall` and `__fastcall`. A declaration must name the convention its counterpart actually uses. A mismatch passes the arguments in the wrong places, leaves the stack unbalanced, and usually crashes.
+
+A 64-bit build has only one calling convention. There, all four keywords are accepted and have no effect.
+
+Name at most one convention. BETA 995 accepts two together without a diagnostic.
+
+> [!NOTE]
+> BETA 990 added **ThisCall** and **FastCall** in interface definitions, and BETA 992 everywhere else; earlier builds refuse them (TB5182).
 
 ### Examples
 
+An API declaration, here with **DeclareWide**:
+
 ```tb check_build
 Private DeclareWide PtrSafe Function _wtoi64 CDecl Lib "msvcrt" (ByVal psz As String) As LongLong
 ```
 
+A `__fastcall` export. On a 32-bit build, `ntdll` exports `RtlUlongByteSwap` with the fastcall convention:
+
+```tb check_build
+Private Declare PtrSafe Function RtlUlongByteSwap FastCall Lib "ntdll" (ByVal Source As Long) As Long
+```
+
+A procedure exported from a standard DLL:
+
 ```tb check_build
 [ DllExport ]
 Public Function MyExportedFunction CDecl(value1 As Long, value2 As Long) As Long
@@ -40,9 +66,46 @@ Public Function MyExportedFunction CDecl(value1 As Long, value2 As Long) As Long
 End Function
 ```
 
-### CDecl Callbacks
+### ThisCall in interfaces
+
+Some C++ interfaces are not COM interfaces, and their methods use thiscall rather than stdcall. RichEdit's `ITextServices` and `ITextHost` are examples. Mark each such member **ThisCall** in the **Interface** definition:
+
+```tb check_build projname=calling-conventions-thiscall
+[InterfaceId("FF7DD8F0-0CCC-4197-86FB-A5591A6BA9B3")]
+[OleAutomation(False)]
+Interface ICounter Extends IUnknown
+    Function Add ThisCall(ByVal Amount As Long) As Long
+    Property Get Total ThisCall() As Long
+End Interface
+```
+
+A class that implements the interface must repeat the convention on each member. An implementation without it, or with a convention the interface member does not have, is an error (TB5004, *Implemented interface member must use the same calling convention as the interface definition*).
+
+```tb check_build projname=calling-conventions-thiscall
+Class Counter
+    Implements ICounter
+
+    Private mTotal As Long
+
+    Private Function ICounter_Add ThisCall(ByVal Amount As Long) As Long Implements ICounter.Add
+        mTotal = mTotal + Amount
+        Return mTotal
+    End Function
+
+    Private Property Get ICounter_Total ThisCall() As Long Implements ICounter.Total
+        Return mTotal
+    End Property
+End Class
+```
+
+### Callbacks
+
+A callback passed to an API must use the convention the API calls it with. Declare a [**Delegate**](../../tB/Core/Delegate) with that convention, use it as the parameter type, and give the target procedure the same keyword. [**AddressOf**](../../tB/Core/AddressOf) of a procedure with a different convention is accepted with a warning only (TB0026).
+
+> [!NOTE]
+> In BETA 995, on a 32-bit build, a call made from twinBASIC code *through* a **ThisCall** or **FastCall** delegate passes its arguments as stdcall does, and fails with *Bad DLL definition*. Calling the procedure directly works. **CDecl** delegates are not affected, and neither is a 64-bit build.
 
-Support for callbacks using `CDecl` is also available. You would pass a delegate that includes `CDecl` as the definition in the prototype. Here is an example code that performs a quicksort using the [`qsort` function](https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-wsprintfw):
+The following example performs a quicksort using the C runtime's [`qsort` function](https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/qsort), which calls its comparator with the cdecl convention:
 
 ```tb check_build
 Private Delegate Function LongComparator CDecl ( _
diff --git a/docs/Features/index.md b/docs/Features/index.md
index cec6d269..0bec8f57 100644
--- a/docs/Features/index.md
+++ b/docs/Features/index.md
@@ -77,7 +77,7 @@ Advanced programming capabilities:
 - Multithreading support via direct API calls
 - Direct assembly insertion with `Emit()`
 - Static linking of OBJ and LIB files
-- Enhanced API declarations (CDecl, variadic args, ByVal UDTs)
+- Enhanced API declarations (CDecl, ThisCall and FastCall calling conventions, variadic args, ByVal UDTs)
 - Parameterized constructors and class exports
 
 ### [Compiler and IDE Features](Compiler-IDE/)
diff --git a/docs/Reference/Core/AddressOf.md b/docs/Reference/Core/AddressOf.md
index 1bed4f42..e67f4a19 100644
--- a/docs/Reference/Core/AddressOf.md
+++ b/docs/Reference/Core/AddressOf.md
@@ -33,7 +33,7 @@ In classic VBA, *procedurename* must name a procedure in a standard [**Module**]
 
 - **Indirect calls back through Basic.** A delegate variable holding an **AddressOf** value can be called directly: `Dim op As Operation = AddressOf Add: r = op(5, 6)`. Classic VBA can pass such pointers between procedures but cannot invoke through them inside Basic. See [**Delegate**](Delegate).
 - **Class, form, and user-control members.** **AddressOf** accepts methods declared on a class, form, or user-control. Take a pointer to an instance method by qualifying the name with the object reference: `AddressOf myInstance.MyMethod`. The resulting pointer remembers the instance --- calling through it dispatches to that object.
-- **CDecl callbacks.** Mark both the target procedure and the matching [**Delegate**](Delegate) (or [**Declare**](Declare) parameter) with **CDecl** to model `cdecl` callbacks. Classic VBA's **AddressOf** is hard-wired to `__stdcall`. See [API Declarations](../../Features/Advanced/API-Declarations#cdecl-callbacks).
+- **Other calling conventions.** Mark both the target procedure and the matching [**Delegate**](Delegate) with **CDecl**, **ThisCall** or **FastCall** to model a callback of that convention. Classic VBA's **AddressOf** is hard-wired to `__stdcall`. See [Calling Conventions](../../Features/Advanced/API-Declarations#calling-conventions).
 - **No `FARPROC` shim needed.** Assigning a function pointer to a local variable is direct --- `Dim lpfn As LongPtr = AddressOf MyFunc` --- without writing an intermediate forwarding procedure.
 
 ### Example
diff --git a/docs/Reference/Core/Declare.md b/docs/Reference/Core/Declare.md
index 4e5b385c..e1122109 100644
--- a/docs/Reference/Core/Declare.md
+++ b/docs/Reference/Core/Declare.md
@@ -31,13 +31,13 @@ Declare Sub...
 Syntax:
 
 - > [ *attributes* ]  
-  > [ **Public** \| **Private** ] **Declare** [ **PtrSafe** ] **Sub** *name* **Lib** "*libname*" [ **(** [ *arglist* ] **)** ]
+  > [ **Public** \| **Private** ] **Declare** [ **PtrSafe** ] **Sub** *name* [ *callconv* ] **Lib** "*libname*" [ **(** [ *arglist* ] **)** ]
 - > [ *attributes* ]  
-  > [ **Public** \| **Private** ] **Declare** [ **PtrSafe** ] **Sub** *name* **Lib** "*libname*" **Alias** "*aliasname*" [ **(** [ *arglist* ] **)** ]
+  > [ **Public** \| **Private** ] **Declare** [ **PtrSafe** ] **Sub** *name* [ *callconv* ] **Lib** "*libname*" **Alias** "*aliasname*" [ **(** [ *arglist* ] **)** ]
 - > [ *attributes* ]  
-  > [ **Public** \| **Private** ] **Declare** [ **PtrSafe** ] **Function** *name* **Lib** "*libname*" [ **(** [ *arglist* ] **)** ] [ **As** *type* ]
+  > [ **Public** \| **Private** ] **Declare** [ **PtrSafe** ] **Function** *name* [ *callconv* ] **Lib** "*libname*" [ **(** [ *arglist* ] **)** ] [ **As** *type* ]
 - > [ *attributes* ]  
-  > [ **Public** \| **Private** ] **Declare** [ **PtrSafe** ] **Function** *name* **Lib** "*libname*" **Alias** "*aliasname*" [ **(** [ *arglist* ] **)** ] [ **As** *type* ]
+  > [ **Public** \| **Private** ] **Declare** [ **PtrSafe** ] **Function** *name* [ *callconv* ] **Lib** "*libname*" **Alias** "*aliasname*" [ **(** [ *arglist* ] **)** ] [ **As** *type* ]
 
 
 *attributes*
@@ -59,6 +59,9 @@ Syntax:
 *name*
 : Any valid procedure name. Note that DLL entry points are case-sensitive.
 
+*callconv*
+: *optional* The calling convention of the DLL procedure: **CDecl**, **ThisCall** or **FastCall**. The default is stdcall, the convention of nearly all Windows API functions. A twinBASIC extension; see [Calling Conventions](../../Features/Advanced/API-Declarations#calling-conventions).
+
 *libname*
 : Name of the DLL or code resource that contains the declared procedure.
 
diff --git a/docs/Reference/Core/Delegate.md b/docs/Reference/Core/Delegate.md
index c0b8d107..c13332c1 100644
--- a/docs/Reference/Core/Delegate.md
+++ b/docs/Reference/Core/Delegate.md
@@ -12,7 +12,8 @@ Declares a function-pointer type --- a named signature that variables, parameter
 > The **Delegate** statement is a twinBASIC extension. In classic VBA, function pointers are untyped **LongPtr** values produced by **AddressOf** and called indirectly through custom mechanisms (`DispCallFunc`, `CallWindowProc` shims, etc.).
 
 Syntax:
-> { **Public** \| **Private** } **Delegate Function** *name* [ **CDecl** ] **(** [ *arglist* ] **)** **As** *type*
+- > { **Public** \| **Private** } **Delegate Function** *name* [ *callconv* ] **(** [ *arglist* ] **)** **As** *type*
+- > { **Public** \| **Private** } **Delegate Sub** *name* [ *callconv* ] **(** [ *arglist* ] **)**
 
 **Public**
 : *required*, or **Private**: a declaration with neither is a syntax error, TB5182. In an ActiveX project, exports the delegate type to the type library so consumers in other projects see *name*. Not allowed in a class, where a delegate must be **Private** (TB5227, *Delegate declarations in class modules must be Private*).
@@ -23,14 +24,14 @@ Syntax:
 *name*
 : The identifier naming the delegate type. Must be a valid twinBASIC identifier.
 
-**CDecl**
-: *optional* Marks the delegate as using the C calling convention (`cdecl` --- caller cleans the stack), used to model callbacks expected by C-runtime APIs such as `qsort`. The default is `stdcall`. See [API Declarations](../../Features/Advanced/API-Declarations#cdecl-callbacks).
+*callconv*
+: *optional* The calling convention of the procedures the delegate refers to: **CDecl**, **ThisCall** or **FastCall**. The default is stdcall. A C-runtime callback such as the comparator of `qsort` is **CDecl**. See [Calling Conventions](../../Features/Advanced/API-Declarations#calling-conventions), which also describes a defect in BETA 995 that affects calls through **ThisCall** and **FastCall** delegates on 32-bit builds.
 
 *arglist*
 : *optional* Parameter signature, written exactly as for a [**Sub**](Sub) or [**Function**](Function) --- comma-separated `[ ByVal | ByRef ] [ Optional ] *varname* [ As *type* ]` parts.
 
 *type*
-: Return type of the delegate's signature.
+: Return type of a **Function** delegate's signature.
 
 After the declaration, *name* may be used wherever a type is allowed: to declare variables and parameters of function-pointer type, as the type of a member of a [**Type**](Type) (UDT), or as a parameter type in a [**Declare**](Declare) statement or an [**Interface**](Interface) member.
 
diff --git a/docs/Reference/Core/Function.md b/docs/Reference/Core/Function.md
index 08406ffb..f4003bd5 100644
--- a/docs/Reference/Core/Function.md
+++ b/docs/Reference/Core/Function.md
@@ -11,7 +11,7 @@ Declares the name, arguments, and code that form the body of a **Function** proc
 
 Syntax:
 > [ *attributes* ]  
-> [ **Public** \| **Private** \| **Friend** \| **Protected** ] [ **Static** ] [ **Overridable** ] **Function** *name* [ **(** **Of** *typevars* **)** ] [ **(** *arglist* **)** ] [ **As** *type* ] [ *binding-clause* ]  
+> [ **Public** \| **Private** \| **Friend** \| **Protected** ] [ **Static** ] [ **Overridable** ] **Function** *name* [ *callconv* ] [ **(** **Of** *typevars* **)** ] [ **(** *arglist* **)** ] [ **As** *type* ] [ *binding-clause* ]  
 > &nbsp;&nbsp;&nbsp;&nbsp; [ *statements* ] ...  
 > &nbsp;&nbsp;&nbsp;&nbsp; [ [ **Let** ] *name* **=** *expression* ] ...  
 > &nbsp;&nbsp;&nbsp;&nbsp; [ **Set** *name* **=** *expression* ] ...  
@@ -45,6 +45,9 @@ Syntax:
 *name*
 : Name of the **Function**; follows standard variable naming conventions.
 
+*callconv*
+: *optional* The calling convention: **CDecl**, **ThisCall** or **FastCall**. The default is stdcall. Needed when native code calls the procedure through a pointer, or when it implements an interface member declared with a convention. See [Calling Conventions](../../Features/Advanced/API-Declarations#calling-conventions).
+
 **Of** *typevars*
 : *optional* One or more type variable names; following standard variable naming conventions. The names are separated by commas. Causes the function to be a generic function.
 
diff --git a/docs/Reference/Core/Interface.md b/docs/Reference/Core/Interface.md
index 70d76b31..bd5db9da 100644
--- a/docs/Reference/Core/Interface.md
+++ b/docs/Reference/Core/Interface.md
@@ -29,7 +29,7 @@ Syntax:
 : *optional* One or more interfaces that *name* extends. An implementing class is required to provide bodies for the inherited methods as well; in twinBASIC, a class can `Implements` *name* and rely on the inherited interfaces being satisfied automatically.
 
 *member-prototype*
-: A header-only declaration. May be a [**Sub**](Sub), [**Function**](Function), [**Property Get**](Property), [**Property Let**](Property), or [**Property Set**](Property) signature, with arguments and return type. **Public**/**Private**/**Friend** modifiers are *not* allowed on members. There is no `End Sub` / `End Function` / `End Property` --- the prototype ends at end of line.
+: A header-only declaration. May be a [**Sub**](Sub), [**Function**](Function), [**Property Get**](Property), [**Property Let**](Property), or [**Property Set**](Property) signature, with arguments and return type. **Public**/**Private**/**Friend** modifiers are *not* allowed on members. There is no `End Sub` / `End Function` / `End Property` --- the prototype ends at end of line. A member can name a calling convention after its name, as in `Function Add ThisCall(ByVal Amount As Long) As Long`, and an implementation must then name the same one; see [Calling Conventions](../../Features/Advanced/API-Declarations#calling-conventions).
 
 **Interface** blocks are valid only in `.twin` source files (not legacy `.bas` or `.cls` files), and must appear *before* the [**Class**](Class) or [**Module**](Module) statement in the file. Interfaces always have project-wide scope.
 
diff --git a/docs/Reference/Core/Sub.md b/docs/Reference/Core/Sub.md
index 21475465..d6b7ac5a 100644
--- a/docs/Reference/Core/Sub.md
+++ b/docs/Reference/Core/Sub.md
@@ -11,7 +11,7 @@ Declares the name, arguments, and code that form the body of a **Sub** procedure
 
 Syntax:
 > [ *attributes* ]  
-> [ **Public** \| **Private** \| **Friend** \| **Protected** ] [ **Static** ] [ **Overridable** ] **Sub** *name* [ **(** **Of** *typevars* **)** ] [ **(** *arglist* **)** ] [ *binding-clause* ]  
+> [ **Public** \| **Private** \| **Friend** \| **Protected** ] [ **Static** ] [ **Overridable** ] **Sub** *name* [ *callconv* ] [ **(** **Of** *typevars* **)** ] [ **(** *arglist* **)** ] [ *binding-clause* ]  
 > &nbsp;&nbsp;&nbsp;&nbsp; [ *statements* ] ...  
 > &nbsp;&nbsp;&nbsp;&nbsp; [ **Exit Sub** ] ...  
 > &nbsp;&nbsp;&nbsp;&nbsp; [ *statements* ] ...  
@@ -41,6 +41,9 @@ Syntax:
 *name*
 : Name of the **Sub**; follows standard variable naming conventions. The special name `New` declares an instance constructor --- see [Inheritance](../../Features/Language/Inheritance) for chained construction with `*baseclass*.New(...)`.
 
+*callconv*
+: *optional* The calling convention: **CDecl**, **ThisCall** or **FastCall**. The default is stdcall. Needed when native code calls the procedure through a pointer, or when it implements an interface member declared with a convention. See [Calling Conventions](../../Features/Advanced/API-Declarations#calling-conventions).
+
 **Of** *typevars*
 : *optional* One or more type variable names, following standard variable naming conventions. The names are separated by commas. Causes the procedure to be a generic **Sub**.
 
diff --git a/docs/Reference/twinBASIC-Additions.md b/docs/Reference/twinBASIC-Additions.md
index 2eca3d52..2fca09ad 100644
--- a/docs/Reference/twinBASIC-Additions.md
+++ b/docs/Reference/twinBASIC-Additions.md
@@ -42,7 +42,7 @@ twinBASIC supports generic types and generic modules using the `Of` keyword. A g
 
 ### New declaration keywords
 
-- [**Delegate**](../tB/Core/Delegate) -- declares a typed function-pointer type; enables type-safe `AddressOf` and CDecl callbacks
+- [**Delegate**](../tB/Core/Delegate) -- declares a typed function-pointer type; enables type-safe `AddressOf` and callbacks in the CDecl, ThisCall and FastCall calling conventions
 - **Enum** member ranges -- enum members can now reference other members by name rather than only literal integers
 
 ### Flow control
@@ -167,7 +167,7 @@ The [**Emit**](../tB/Modules/HiddenModule/Emit) / [**EmitAny**](../tB/Modules/Hi
 Beyond the standard `Declare`, twinBASIC adds:
 
 - `DeclareWide` --- disables ANSI/Unicode conversion for string arguments
-- `CDecl` calling convention on both declares and regular functions
+- `CDecl`, `ThisCall` and `FastCall` calling conventions on declares, procedures, delegates and interface members
 - `ByVal` UDT passing
 - Variadic (`CDecl` + `ParamArray ... As Any()`) parameter lists
 
diff --git a/docs/Tutorials/Windows-API.md b/docs/Tutorials/Windows-API.md
index 4cde6567..a8006ca6 100644
--- a/docs/Tutorials/Windows-API.md
+++ b/docs/Tutorials/Windows-API.md
@@ -265,7 +265,7 @@ End Sub
 
 ## Where to go next
 
-- **Enhanced API Declarations** -- `DeclareWide`, `CDecl`, `ByVal` UDTs, variadic arguments: [Features → Enhanced API Declarations](../Features/Advanced/API-Declarations)
+- **Enhanced API Declarations** -- `DeclareWide`, calling conventions (`CDecl`, `ThisCall`, `FastCall`), `ByVal` UDTs, variadic arguments: [Features → Enhanced API Declarations](../Features/Advanced/API-Declarations)
 - **Declarations already written** -- the community package WinDevLib declares common Windows APIs and COM interfaces, with 64-bit-compatible types: [WinDevLib on GitHub](https://github.com/fafalone/WinDevLib)
 - **Forms basics** -- the standard VB controls and event model: [Forms basics](Forms)
 - **Unit testing** -- verifying functions that wrap API calls: [Writing unit tests with Assert](Testing-with-Assert)

From 89aace27e02f1808d0cfd807eb265d1282e26225 Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 17:14:51 +0200
Subject: [PATCH 15/22] bugs: an embedded package with no Packages folder puts
 995's compiler in a crash loop

---
 BUGS-TO-REPORT.md          | 27 +++++++++++++++++++++++++++
 test/ide/packages.test.mjs | 10 +++++-----
 2 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/BUGS-TO-REPORT.md b/BUGS-TO-REPORT.md
index a1e41994..9b4c7ed1 100644
--- a/BUGS-TO-REPORT.md
+++ b/BUGS-TO-REPORT.md
@@ -980,6 +980,33 @@ and v2 runs at once.
 
 ---
 
+## Embedding a package with no `Packages` folder puts the compiler in a crash loop
+
+**Build:** BETA 995
+**Severity:** the project cannot be compiled again; the IDE drops into Safe Mode.
+
+1. Pack a package tree that has no `Packages` folder into a `.twinpack`. The tree may lack
+   `ImportedTypeLibraries` and `Miscellaneous` as well; neither matters.
+2. In a project, Settings → References → Available Packages → *Import from file...* the
+   `.twinpack`, tick it, and apply.
+3. The console shows `[PROJECT] twinBASIC project saving to disk [DONE]`, then `restarting from
+   FILE` four times about two seconds apart, and the IDE reports "Compiler crash loop detected.
+   Restarting in SAFE mode."
+
+An empty `Packages` folder in the package tree is enough to prevent it: the same steps with that
+folder alone, or with all three, restart the compiler once and run the package. Every package
+the IDE exports has all three folders, so only a hand-made tree meets this.
+
+**What does not reproduce it:** a project with the same package already embedded under
+`Packages\DocProbePkg`, without the folder, packed by `scripts/impexp.mjs` and opened cold,
+compiles clean (also on BETA 983). So the loop needs the package to be embedded by the IDE.
+BETA 983 has not been tried through the IDE: in a lane its References page never finishes loading.
+
+**Found by** `ide-test.bat`'s `packages` lane, with the package's folders varied one at a time,
+and one run watched with `--show`.
+
+---
+
 ## A call through a `FastCall` or `ThisCall` delegate is made as stdcall on win32
 
 **Build:** BETA 995
diff --git a/test/ide/packages.test.mjs b/test/ide/packages.test.mjs
index 67c1d8b9..35e942b2 100644
--- a/test/ide/packages.test.mjs
+++ b/test/ide/packages.test.mjs
@@ -122,11 +122,11 @@ scenario("Import from file... in the Packages dialog", (lane) => {
 // probes/packages/DocProbePkg, which the first test above uses as it is. v2
 // has its version fields in Settings at 2.0.0.0 and its function returns 2.
 // Both also get the three empty folders every exported package has,
-// ImportedTypeLibraries, Miscellaneous and Packages: BETA 995's compiler dies
-// at start on a project that embeds a package without them, three times, and
-// the IDE then drops into Safe Mode, where nothing runs. (Measured with a copy
-// of the tree with and without the folders; which of the three it needs was not
-// narrowed.) Each test works on a copy of the host project in its own folder,
+// ImportedTypeLibraries, Miscellaneous and Packages. Packages is the one that
+// matters: without it, BETA 995's compiler crashes on each restart after the
+// embedding Apply, and the IDE drops into Safe Mode, where nothing runs
+// (BUGS-TO-REPORT.md, "Embedding a package with no Packages folder puts the
+// compiler in a crash loop"). Each test works on a copy of the host project in its own folder,
 // because applying writes the project's settings. The copy's Main is empty
 // until v1 is embedded, since the host cannot compile before the package is
 // referenced; the test then writes Main in the editor.

From e280b730e0a9cd83cc349f97fd5aaf815eaec159 Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 17:36:30 +0200
Subject: [PATCH 16/22] impexp: import adds the empty folders the IDE always
 writes, to the project and each embedded package

---
 BUGS-TO-REPORT.md                            | 13 ++--
 docs/Features/Packages/Import-export tool.md | 10 +++
 scripts/impexp.mjs                           | 64 ++++++++++++++++--
 scripts/impexp.py                            | 69 ++++++++++++++++++--
 test/ide/packages.test.mjs                   | 15 ++---
 5 files changed, 143 insertions(+), 28 deletions(-)

diff --git a/BUGS-TO-REPORT.md b/BUGS-TO-REPORT.md
index 9b4c7ed1..c73ad4b2 100644
--- a/BUGS-TO-REPORT.md
+++ b/BUGS-TO-REPORT.md
@@ -983,9 +983,12 @@ and v2 runs at once.
 ## Embedding a package with no `Packages` folder puts the compiler in a crash loop
 
 **Build:** BETA 995
-**Severity:** the project cannot be compiled again; the IDE drops into Safe Mode.
+**Severity:** low. The input is invalid, and nothing in a normal workflow makes it: every package
+the IDE writes has the folder, and `scripts/impexp.mjs` and `impexp.py` add it when a tree
+lacks it. A crash is still a poor answer to it.
 
-1. Pack a package tree that has no `Packages` folder into a `.twinpack`. The tree may lack
+1. Pack a package tree that has no `Packages` folder into a `.twinpack`. The tB executable's
+   `import` packs such a tree as it is; the repository's scripts no longer do. The tree may lack
    `ImportedTypeLibraries` and `Miscellaneous` as well; neither matters.
 2. In a project, Settings → References → Available Packages → *Import from file...* the
    `.twinpack`, tick it, and apply.
@@ -994,12 +997,10 @@ and v2 runs at once.
    Restarting in SAFE mode."
 
 An empty `Packages` folder in the package tree is enough to prevent it: the same steps with that
-folder alone, or with all three, restart the compiler once and run the package. Every package
-the IDE exports has all three folders, so only a hand-made tree meets this.
+folder alone, or with all three, restart the compiler once and run the package.
 
 **What does not reproduce it:** a project with the same package already embedded under
-`Packages\DocProbePkg`, without the folder, packed by `scripts/impexp.mjs` and opened cold,
-compiles clean (also on BETA 983). So the loop needs the package to be embedded by the IDE.
+`Packages\DocProbePkg`, without the folder, and opened cold compiles clean (also on BETA 983). So the loop needs the package to be embedded by the IDE.
 BETA 983 has not been tried through the IDE: in a lane its References page never finishes loading.
 
 **Found by** `ide-test.bat`'s `packages` lane, with the package's folders varied one at a time,
diff --git a/docs/Features/Packages/Import-export tool.md b/docs/Features/Packages/Import-export tool.md
index 7441ed2d..a153e94f 100644
--- a/docs/Features/Packages/Import-export tool.md	
+++ b/docs/Features/Packages/Import-export tool.md	
@@ -110,6 +110,7 @@ message that names only `export` and `import`; given no arguments at all, it doe
 | `export` refused because `--overwrite` is missing | writes the files that were not there yet | writes nothing |
 | Files in the folder that the project does not hold | left in place, with no warning | left in place, and listed in a warning |
 | A `.git` folder | packed by `import`, and written back by `export` | skipped by both |
+| The IDE's empty folders, when the folder lacks them | left out | added by `import`, see below |
 | A damaged project file | shows a message box and waits until it is closed | fails with an error |
 | A printing command, when the project lacks the file | prints nothing | fails with an error |
 | Error messages | on standard output | on standard error |
@@ -131,6 +132,15 @@ v1.8)* template. The script packs them. An export made by the IDE's **File → E
 stops the same way, because it holds the compiler packages under `Packages\`; see [Packing
 the export back into a project](../../tB/IDE/Project/Menu/File#packing-the-export-back-into-a-project).
 
+**The script's `import` adds the folders the IDE always writes.** Every project and package the
+IDE exports has `ImportedTypeLibraries`, `Miscellaneous`, `Packages`, `Resources` and `Sources`
+folders, even when they are empty. Git does not store an empty folder, so a tree checked out
+from a repository usually lacks some of them. `import` adds each missing one as an empty folder,
+in the project and in each package under its `Packages` folder, and lists what it added. The
+folder on disk is not changed. A package without its `Packages` folder is not only incomplete:
+once the IDE embeds it in a project, the IDE's compiler crashes each time it restarts, and
+after four tries the IDE starts in Safe Mode.
+
 ## Checking the result
 
 The tB executable's exit code is `0` after every failure it reports itself, so a build script
diff --git a/scripts/impexp.mjs b/scripts/impexp.mjs
index 86c3d8fe..b0f05ad2 100644
--- a/scripts/impexp.mjs
+++ b/scripts/impexp.mjs
@@ -90,6 +90,13 @@ const META_NAME = ".meta";
 // --overwrite writes it back over the live one.
 const GIT_NAME = ".git";
 
+// The folders the IDE writes into every project and package it exports, even
+// when they are empty. Git keeps no empty folder, so a tree cloned from a
+// repository lacks them, and the IDE's compiler crashes in a loop on a package
+// with no Packages folder once it is embedded. Import adds any that are
+// missing, to the project and to each package under its Packages folder.
+const STANDARD_FOLDERS = ["ImportedTypeLibraries", "Miscellaneous", "Packages", "Resources", "Sources"];
+
 const PROJECT_FILE = /\.(twinproj|twinpack)$/i;
 
 // -------------------------- Parser (binary -> tree) --------------------------
@@ -454,12 +461,25 @@ function projectNameIn(settingsPath) {
   }
 }
 
-function buildTree(dirPath, rel, self, skipped) {
+function buildTree(dirPath, rel, self, skipped, added) {
   const subdirs = [],
     files = [];
-  for (const name of fs.readdirSync(dirPath).sort(byCodePoint)) {
+  const names = fs.readdirSync(dirPath);
+  // The standard folders this tree lacks, if it is the project or a package
+  // embedded in it.
+  const missing = new Set();
+  if (rel === "" || (/^packages\/[^/]+$/i.test(rel) && names.includes("Settings"))) {
+    const have = new Set(names.map((n) => n.toLowerCase()));
+    for (const folder of STANDARD_FOLDERS) if (!have.has(folder.toLowerCase())) missing.add(folder);
+  }
+  for (const name of [...names, ...missing].sort(byCodePoint)) {
     const full = path.join(dirPath, name);
     const entryRel = rel ? `${rel}/${name}` : name;
+    if (missing.has(name)) {
+      subdirs.push(name);
+      added.push(entryRel);
+      continue;
+    }
     if (name.toLowerCase() === GIT_NAME) {
       skipped.push({ rel: entryRel, why: "Git's own folder" });
       continue;
@@ -473,7 +493,11 @@ function buildTree(dirPath, rel, self, skipped) {
 
   const children = [];
   for (const d of subdirs) {
-    children.push(buildTree(path.join(dirPath, d), rel ? `${rel}/${d}` : d, self, skipped));
+    children.push(
+      missing.has(d)
+        ? { kind: "directory", name: d, revision: 0x0000, flags: FLAGS.None, category: categoryFor(d), children: [] }
+        : buildTree(path.join(dirPath, d), rel ? `${rel}/${d}` : d, self, skipped, added),
+    );
   }
   for (const f of files) {
     children.push({
@@ -513,8 +537,9 @@ function importProject(projectPath, folder, { overwrite = false } = {}) {
   if (existing === "file" && !overwrite)
     throw new Refusal("exists", `${projectPath} already exists, and --overwrite is not set`, HINT_IMPORT);
 
-  const skipped = [];
-  const root = buildTree(path.resolve(folder), "", pathKey(projectPath), skipped);
+  const skipped = [],
+    added = [];
+  const root = buildTree(path.resolve(folder), "", pathKey(projectPath), skipped, added);
   root.name = projectNameIn(settings) ?? root.name;
   root.category = CATEGORY.Default;
   const buf = serialize(root);
@@ -531,7 +556,7 @@ function importProject(projectPath, folder, { overwrite = false } = {}) {
       }
     }
   })(root);
-  return { name: root.name, size: buf.length, files: fileCount, folders: dirCount, skipped };
+  return { name: root.name, size: buf.length, files: fileCount, folders: dirCount, skipped, added };
 }
 
 // -------------------------- Printing a root document -------------------------
@@ -713,6 +738,32 @@ function selfTest() {
       eq(parse(fs.readFileSync(out)).name, "MyTree", "root name");
     });
 
+    test("Import adds the empty folders the IDE expects, to the project and each package in it", () => {
+      const src = at("bare", "Git");
+      for (const d of ["resources", "Packages/Pkg", "Packages/Pkg/Sources", "Packages/NotPkg"]) {
+        fs.mkdirSync(path.join(src, d), { recursive: true });
+      }
+      fs.writeFileSync(path.join(src, "Settings"), "{}");
+      fs.writeFileSync(path.join(src, "Packages", "Pkg", "Settings"), "{}");
+      const r = importProject(at("bare", "Git.twinproj"), src);
+      eq(
+        r.added.join(),
+        "ImportedTypeLibraries,Miscellaneous,Sources,Packages/Pkg/ImportedTypeLibraries,Packages/Pkg/Miscellaneous," +
+          "Packages/Pkg/Packages,Packages/Pkg/Resources",
+        "added",
+      );
+      const back = parse(fs.readFileSync(at("bare", "Git.twinproj")));
+      eq(
+        [...contents(back).keys()].join(),
+        "ImportedTypeLibraries/,Miscellaneous/,Packages/,Packages/NotPkg/,Packages/Pkg/," +
+          "Packages/Pkg/ImportedTypeLibraries/,Packages/Pkg/Miscellaneous/,Packages/Pkg/Packages/," +
+          "Packages/Pkg/Resources/,Packages/Pkg/Sources/,Packages/Pkg/Settings,Sources/,resources/,Settings",
+        "contents",
+      );
+      eq(back.children.find((c) => c.name === "Miscellaneous").category, CATEGORY.Miscellaneous, "category");
+      eq(fs.readdirSync(src).sort(byCodePoint).join(), "Packages,Settings,resources", "the tree on disk changed");
+    });
+
     test("Export without --overwrite refuses, and writes nothing", () => {
       fs.rmSync(path.join(tree, "Settings"));
       fs.writeFileSync(path.join(tree, "Sources", "Module1.twin"), "CHANGED");
@@ -990,6 +1041,7 @@ function main(argv) {
     try {
       const r = verb === "export" ? exportProject(project, folder, opts) : importProject(project, folder, opts);
       for (const s of r.skipped) console.log(`  skipped ${s.rel} (${s.why})`);
+      for (const a of r.added ?? []) console.log(`  added ${a} (an empty folder the IDE expects)`);
       console.log(
         `  ${count(r.files, "file")}, ${count(r.folders, "folder")}` +
           (r.size === undefined ? "" : `, ${r.size} bytes`),
diff --git a/scripts/impexp.py b/scripts/impexp.py
index 82a37336..8f9944f2 100644
--- a/scripts/impexp.py
+++ b/scripts/impexp.py
@@ -88,6 +88,14 @@
 # --overwrite writes it back over the live one.
 GIT_NAME = '.git'
 
+# The folders the IDE writes into every project and package it exports, even
+# when they are empty. Git keeps no empty folder, so a tree cloned from a
+# repository lacks them, and the IDE's compiler crashes in a loop on a package
+# with no Packages folder once it is embedded. Import adds any that are
+# missing, to the project and to each package under its Packages folder.
+STANDARD_FOLDERS = ('ImportedTypeLibraries', 'Miscellaneous', 'Packages',
+                    'Resources', 'Sources')
+
 PROJECT_FILE = re.compile(r'\.(twinproj|twinpack)$', re.IGNORECASE)
 
 # -------------------------- Parser (binary -> tree) --------------------------
@@ -460,11 +468,23 @@ def _project_name_in(settings_path):
     return name if isinstance(name, str) and name else None
 
 
-def _build_tree(dir_path, rel, self_key, skipped):
+def _build_tree(dir_path, rel, self_key, skipped, added):
     subdirs, files = [], []
-    for name in sorted(os.listdir(dir_path)):
+    names = os.listdir(dir_path)
+    # The standard folders this tree lacks, if it is the project or a package
+    # embedded in it.
+    missing = set()
+    if rel == '' or (re.fullmatch(r'packages/[^/]+', rel, re.IGNORECASE)
+                     and 'Settings' in names):
+        have = {n.lower() for n in names}
+        missing = {f for f in STANDARD_FOLDERS if f.lower() not in have}
+    for name in sorted(names + list(missing)):
         full = os.path.join(dir_path, name)
         entry_rel = f'{rel}/{name}' if rel else name
+        if name in missing:
+            subdirs.append(name)
+            added.append(entry_rel)
+            continue
         if name.lower() == GIT_NAME:
             skipped.append(dict(rel=entry_rel, why="Git's own folder"))
             continue
@@ -480,9 +500,16 @@ def _build_tree(dir_path, rel, self_key, skipped):
 
     children = []
     for d in subdirs:
+        if d in missing:
+            children.append(dict(
+                kind='directory', name=d,
+                revision=0x0000, flags=FLAGS_NONE,
+                category=_category_for(d), children=[],
+            ))
+            continue
         children.append(_build_tree(os.path.join(dir_path, d),
                                     f'{rel}/{d}' if rel else d,
-                                    self_key, skipped))
+                                    self_key, skipped, added))
     for f in files:
         with open(os.path.join(dir_path, f), 'rb') as fh:
             content = fh.read()
@@ -519,9 +546,9 @@ def import_project(project_path, folder, overwrite=False):
         raise Refusal('exists', f'{project_path} already exists, and '
                       '--overwrite is not set', HINT_IMPORT)
 
-    skipped = []
+    skipped, added = [], []
     root = _build_tree(os.path.abspath(folder), '', _path_key(project_path),
-                       skipped)
+                       skipped, added)
     root['name'] = _project_name_in(settings) or root['name']
     root['category'] = CATEGORY_DEFAULT
     buf = serialize(root)
@@ -539,7 +566,7 @@ def count(e):
 
     count(root)
     return dict(name=root['name'], size=len(buf), files=tally['files'],
-                folders=tally['folders'], skipped=skipped)
+                folders=tally['folders'], skipped=skipped, added=added)
 
 
 # -------------------------- Printing a root document -------------------------
@@ -739,6 +766,34 @@ def t_fallback_name():
         test('Import names the root after the folder when Settings has no name',
              t_fallback_name)
 
+        def t_standard_folders():
+            src = at('bare', 'Git')
+            for d in ('resources', 'Packages/Pkg', 'Packages/Pkg/Sources',
+                      'Packages/NotPkg'):
+                os.makedirs(os.path.join(src, d))
+            with open(os.path.join(src, 'Settings'), 'w') as f:
+                f.write('{}')
+            with open(os.path.join(src, 'Packages', 'Pkg', 'Settings'), 'w') as f:
+                f.write('{}')
+            r = import_project(at('bare', 'Git.twinproj'), src)
+            eq(','.join(r['added']),
+               'ImportedTypeLibraries,Miscellaneous,Sources,'
+               'Packages/Pkg/ImportedTypeLibraries,Packages/Pkg/Miscellaneous,'
+               'Packages/Pkg/Packages,Packages/Pkg/Resources', 'added')
+            back = read_parsed(at('bare', 'Git.twinproj'))
+            eq(','.join(contents(back)),
+               'ImportedTypeLibraries/,Miscellaneous/,Packages/,Packages/NotPkg/,'
+               'Packages/Pkg/,Packages/Pkg/ImportedTypeLibraries/,'
+               'Packages/Pkg/Miscellaneous/,Packages/Pkg/Packages/,'
+               'Packages/Pkg/Resources/,Packages/Pkg/Sources/,Packages/Pkg/Settings,'
+               'Sources/,resources/,Settings', 'contents')
+            misc = [c for c in back['children'] if c['name'] == 'Miscellaneous'][0]
+            eq(misc['category'], CATEGORY_MISCELLANEOUS, 'category')
+            eq(','.join(sorted(os.listdir(src))), 'Packages,Settings,resources',
+               'the tree on disk changed')
+        test('Import adds the empty folders the IDE expects, to the project and '
+             'each package in it', t_standard_folders)
+
         def t_export_refuses():
             os.remove(os.path.join(tree, 'Settings'))
             with open(os.path.join(tree, 'Sources', 'Module1.twin'), 'w') as f:
@@ -1073,6 +1128,8 @@ def main(argv):
                 r = import_project(project, folder, overwrite=overwrite)
             for s in r['skipped']:
                 _out(f"  skipped {s['rel']} ({s['why']})")
+            for a in r.get('added', []):
+                _out(f'  added {a} (an empty folder the IDE expects)')
             _out(f"  {_count(r['files'], 'file')}, {_count(r['folders'], 'folder')}"
                  + (f", {r['size']} bytes" if 'size' in r else ''))
             if r.get('repeated'):
diff --git a/test/ide/packages.test.mjs b/test/ide/packages.test.mjs
index 35e942b2..64fbdb31 100644
--- a/test/ide/packages.test.mjs
+++ b/test/ide/packages.test.mjs
@@ -22,7 +22,7 @@
 
 import assert from "node:assert/strict";
 import { execFileSync } from "node:child_process";
-import { cpSync, mkdirSync, readFileSync, writeFileSync } from "node:fs";
+import { cpSync, readFileSync, writeFileSync } from "node:fs";
 import path from "node:path";
 import { before, test } from "node:test";
 import { fileURLToPath } from "node:url";
@@ -121,9 +121,8 @@ scenario("Import from file... in the Packages dialog", (lane) => {
 // Both versions are generated into the lane's work folder from the v1 tree at
 // probes/packages/DocProbePkg, which the first test above uses as it is. v2
 // has its version fields in Settings at 2.0.0.0 and its function returns 2.
-// Both also get the three empty folders every exported package has,
-// ImportedTypeLibraries, Miscellaneous and Packages. Packages is the one that
-// matters: without it, BETA 995's compiler crashes on each restart after the
+// impexp.mjs adds the empty folders every exported package has; without its
+// Packages folder, BETA 995's compiler crashes on each restart after the
 // embedding Apply, and the IDE drops into Safe Mode, where nothing runs
 // (BUGS-TO-REPORT.md, "Embedding a package with no Packages folder puts the
 // compiler in a crash loop"). Each test works on a copy of the host project in its own folder,
@@ -140,9 +139,6 @@ End Module
 
 const VERSION_PREFIX = "DocProbeVersion=";
 
-// The three folders an exported package always has.
-const PACKAGE_FOLDERS = ["ImportedTypeLibraries", "Miscellaneous", "Packages"];
-
 // The References page's rows, for a failure message: the list each is in,
 // its name, and whether its tick box is ticked.
 const ROWS_JS = `[...document.querySelectorAll(".referencesListRow")].map((r) => ({
@@ -165,12 +161,11 @@ scenario("Replacing an embedded package", (lane) => {
   let v2;
   const sleep = (ms) => new Promise((r) => setTimeout(r, ms));
 
-  // A copy of the v1 tree in the work folder, with the empty folders, for
-  // `version`, packed to a .twinpack as the first test does.
+  // A copy of the v1 tree in the work folder for `version`, packed to a
+  // .twinpack as the first test does.
   function packVersion(version) {
     const tree = path.join(lane.work, `DocProbePkg-v${version}`);
     cpSync(PKG, tree, { recursive: true });
-    for (const folder of PACKAGE_FOLDERS) mkdirSync(path.join(tree, folder), { recursive: true });
     const settings = path.join(tree, "Settings");
     const source = path.join(tree, "Sources", "DocProbe.twin");
     writeFileSync(

From 6703b4afedbac2ff2ee03029f944de8f6f082c8c Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 17:47:26 +0200
Subject: [PATCH 17/22] test: an ide-test lane for Stop at a failed Assert; two
 editor BUGS entries checked against 995's main.js

---
 BUGS-TO-REPORT.md                           | 15 +++--
 test/ide/assert.test.mjs                    | 69 +++++++++++++++++++
 test/ide/lanes.mjs                          |  7 +-
 test/ide/probes/assert/Settings             | 75 +++++++++++++++++++++
 test/ide/probes/assert/Sources/Startup.twin | 16 +++++
 5 files changed, 175 insertions(+), 7 deletions(-)
 create mode 100644 test/ide/assert.test.mjs
 create mode 100644 test/ide/probes/assert/Settings
 create mode 100644 test/ide/probes/assert/Sources/Startup.twin

diff --git a/BUGS-TO-REPORT.md b/BUGS-TO-REPORT.md
index c73ad4b2..33f0554a 100644
--- a/BUGS-TO-REPORT.md
+++ b/BUGS-TO-REPORT.md
@@ -884,7 +884,7 @@ runs on from the next line as the panel says.
 
 ## Stop at a run-time error ends only the procedure that raised it
 
-**Build:** BETA 995 (`ide-test.bat`'s `debugger` lane asserts it); BETA 983 for the `Assert` case
+**Build:** BETA 995 (`ide-test.bat`'s `debugger` and `assert` lanes assert it, and pass on BETA 983 as well)
 **Severity:** the program goes on running after the user asked it to stop.
 
 A `Sub Main` that calls a procedure which raises an untrapped error, and prints a line after
@@ -898,9 +898,10 @@ prints `aborted` and ends the whole run.
 **Its worst consequence is a false pass.** At a failed `Assert` --- whose error is raised by the
 assertion's own procedure --- **Stop**, and **Run → End** too, end only that procedure: the test
 carries on past the failed check, and a runner in the shape `Testing-with-Assert.md` teaches then
-prints `All PadLeft tests passed.` Three trials, one per button (**Ignore (Resume Next)** does the
-same, as it should). Moving execution to the test's `End Sub` with **Set Next Statement** and then
-choosing **Run → End** makes it an ordinary break, and the run is aborted (two trials).
+prints `All PadLeft tests passed.` The `assert` lane checks the panel's **Stop** and the Stop
+command that the toolbar and **Run → End** run. By hand on BETA 983, **Ignore (Resume Next)** did
+the same, as it should, and moving execution to the test's `End Sub` with **Set Next Statement**
+and then choosing **Run → End** made it an ordinary break, and the run was aborted (two trials).
 
 **Found by** the same probe; the assertion case by the fix pass for the Assert tutorial.
 
@@ -1159,7 +1160,8 @@ key events and checks each result. Every case in the table is a test in that lan
 
 ## F1 and the fold icon toggle the signature help, then fail
 
-**Build:** BETA 995 for F1 (`addin-test.bat`'s `keys` lane asserts it); BETA 983 for the fold icon
+**Build:** BETA 995 for F1 (`addin-test.bat`'s `keys` lane asserts it); the fold icon was
+clicked on BETA 983, and `toggleSigHelp` and both callers are unchanged in BETA 995's `ide/main.js`
 **Severity:** cosmetic --- the toggle works, but every F1 adds `command failed:
 "tbHelp_ToggleExpandSignatureHelp"` to the DEBUG CONSOLE, and every click on the icon throws
 in the page.
@@ -1184,7 +1186,8 @@ line, and the click in a harness IDE with `Runtime.exceptionThrown` recorded ove
 
 ## Typing just after a file opens at a position puts the text at that position, in reverse
 
-**Build:** BETA 983
+**Build:** BETA 983; `parseDocumentDecorations` and `revealLineInEditor` are unchanged in BETA
+995's `ide/main.js`
 **Severity:** typed text goes to the wrong place and in the wrong order, and nothing shows
 that it happened.
 
diff --git a/test/ide/assert.test.mjs b/test/ide/assert.test.mjs
new file mode 100644
index 00000000..c86193e1
--- /dev/null
+++ b/test/ide/assert.test.mjs
@@ -0,0 +1,69 @@
+// The debugger at a failed assertion, measured: what Stop does when the error
+// panel opens for an error the Assert package raised. The project in
+// probes/assert has Main call a test whose one assertion fails, and prints a
+// line before and after the assertion and after the call, as the runner in
+// docs/Tutorials/Testing-with-Assert.md does.
+//
+// Each test states what BETA 983 and 995 do. If one fails after an IDE update, the
+// IDE has changed: update the NOTE under "Running the tests" in
+// Testing-with-Assert.md and the "Stop at a run-time error" entry in
+// BUGS-TO-REPORT.md, and then this file.
+//
+// Run it with ide-test.bat, which gives it a lane; on its own it is skipped.
+
+import assert from "node:assert/strict";
+import path from "node:path";
+import { before, test } from "node:test";
+import { fileURLToPath } from "node:url";
+import { consoleMark, linesSince } from "../../scripts/lib/tb-ide-console.mjs";
+import { click, waitFor } from "../../scripts/lib/tb-operate.mjs";
+import { scenario } from "../addin/scenario.mjs";
+
+const HERE = path.dirname(fileURLToPath(import.meta.url));
+const PROJECT = path.join(HERE, "probes", "assert");
+
+// Whether the debugger is running, and the error panel's buttons, which are
+// there only at an error.
+const STATE_JS = `(() => ({
+  running: !!context.codeExecuting.value,
+  panel: [...document.querySelectorAll(".errorWidgetButton")].map((b) => b.textContent.trim()),
+}))()`;
+const BEFORE = ["Executing 'Main'...", "main start", "test start"];
+const AFTER = ["test after assert", "All PadLeft tests passed."];
+
+scenario("the debugger at a failed assertion", (lane) => {
+  let c;
+  let mark;
+  const state = () => c.evaluate(STATE_JS);
+  const printed = () => linesSince(c, mark);
+
+  // Start a run from the editor, as F5 does, and wait for the panel.
+  async function runToFailure() {
+    mark = await consoleMark(c);
+    await c.evaluate(`executeIdeCommand("tbDebug_StartOrContinue")`);
+    assert.ok(await waitFor(c, async () => (await state()).panel.length, { timeout: 60 * 1000 }), "no error panel");
+    assert.deepEqual(await printed(), BEFORE);
+  }
+  async function stopped() {
+    assert.ok(await waitFor(c, async () => !(await state()).running), "the run did not stop");
+    // The program's lines, without the time taken and the debugger's own line.
+    return (await printed()).slice(0, BEFORE.length + AFTER.length);
+  }
+
+  before(async () => {
+    c = await lane.open(PROJECT);
+  });
+
+  test("the panel's Stop ends only the assertion: the test and the runner go on", async () => {
+    await runToFailure();
+    await click(c, { css: ".errorWidgetButton", text: "Stop" });
+    assert.deepEqual(await stopped(), [...BEFORE, ...AFTER]);
+  });
+
+  // main.js binds the toolbar's stopIcon and the Run menu's End to this command.
+  test("the Stop command, as the toolbar and Run > End give it, does the same", async () => {
+    await runToFailure();
+    await c.evaluate(`executeIdeCommand("tbDebug_Stop")`);
+    assert.deepEqual(await stopped(), [...BEFORE, ...AFTER]);
+  });
+});
diff --git a/test/ide/lanes.mjs b/test/ide/lanes.mjs
index 5e057b6e..fc61b322 100644
--- a/test/ide/lanes.mjs
+++ b/test/ide/lanes.mjs
@@ -15,4 +15,9 @@
 //             same one never run at once. Settings that are not named here are
 //             left changed after the run.
 
-export default [{ file: "export.test.mjs" }, { file: "debugger.test.mjs" }, { file: "packages.test.mjs" }];
+export default [
+  { file: "export.test.mjs" },
+  { file: "debugger.test.mjs" },
+  { file: "assert.test.mjs" },
+  { file: "packages.test.mjs" },
+];
diff --git a/test/ide/probes/assert/Settings b/test/ide/probes/assert/Settings
new file mode 100644
index 00000000..3ffd0ccd
--- /dev/null
+++ b/test/ide/probes/assert/Settings
@@ -0,0 +1,75 @@
+{
+	"configuration.inherits": "Defaults",
+	"project.appTitle": "AssertProbe",
+	"project.buildPath": "${SourcePath}\\Build\\${ProjectName}_${Architecture}.${FileExtension}",
+	"project.buildType": "Standard EXE",
+	"project.description": "test/ide/assert.test.mjs opens it in a lane's copy of the install, runs it in the debugger, and operates the error panel when an assertion fails.",
+	"project.exportPathIsV2": true,
+	"project.id": "{7B247500-0000-4000-9000-7B2475000005}",
+	"project.name": "AssertProbe",
+	"project.optionExplicit": true,
+	"project.references": [
+		{
+			"id": "{00020430-0000-0000-C000-000000000046}",
+			"lcid": 0,
+			"name": "OLE Automation",
+			"path32": "C:\\Windows\\SysWOW64\\stdole2.tlb",
+			"path64": "C:\\Windows\\System32\\stdole2.tlb",
+			"symbolId": "stdole",
+			"versionMajor": 2,
+			"versionMinor": 0
+		},
+		{
+			"id": "{F50B82D0-DCAB-43FE-9631-11959D4A4728}",
+			"isCompilerPackage": true,
+			"licence": "MIT",
+			"name": "[COMPILER PACKAGE] twinBASIC - VB Compatibility Package (Forms)",
+			"path32": "",
+			"path64": "",
+			"publisher": "TWINBASIC-COMPILER",
+			"symbolId": "VB",
+			"versionBuild": 0,
+			"versionMajor": 0,
+			"versionMinor": 0,
+			"versionRevision": 31
+		},
+		{
+			"id": "{C192FB39-64CA-4D9B-B477-A5502F48EFCC}",
+			"isCompilerPackage": true,
+			"licence": "MIT",
+			"name": "[COMPILER PACKAGE] twinBASIC - App global class object",
+			"path32": "",
+			"path64": "",
+			"publisher": "TWINBASIC-COMPILER",
+			"symbolId": "AppGlobalClassProject",
+			"versionBuild": 0,
+			"versionMajor": 1,
+			"versionMinor": 0,
+			"versionRevision": 0
+		},
+		{
+			"id": "{9847A10D-8987-44B2-8B87-EA77DEF7F1D9}",
+			"isCompilerPackage": true,
+			"licence": "MIT",
+			"name": "[COMPILER PACKAGE] Assert",
+			"path32": "",
+			"path64": "",
+			"publisher": "TWINBASIC-COMPILER",
+			"symbolId": "Assert",
+			"versionBuild": 0,
+			"versionMajor": 0,
+			"versionMinor": 0,
+			"versionRevision": 24
+		}
+	],
+	"project.settingsVersion": 1,
+	"project.startupObject": "Sub Main",
+	"project.warnings": {
+		"errors": [],
+		"hints": [],
+		"ignored": [],
+		"info": [],
+		"warnings": []
+	},
+	"runtime.useUnicodeStandardLibrary": true
+}
diff --git a/test/ide/probes/assert/Sources/Startup.twin b/test/ide/probes/assert/Sources/Startup.twin
new file mode 100644
index 00000000..ee91ce52
--- /dev/null
+++ b/test/ide/probes/assert/Sources/Startup.twin
@@ -0,0 +1,16 @@
+' The project test/ide/assert.test.mjs runs in the debugger. TestPadLeft's
+' assertion fails, and the error is raised inside the Assert package; each line
+' around it prints, so the DEBUG CONSOLE shows how far the program got.
+Module Startup
+    Public Sub Main()
+        Debug.Print "main start"
+        TestPadLeft
+        Debug.Print "All PadLeft tests passed."
+    End Sub
+
+    Private Sub TestPadLeft()
+        Debug.Print "test start"
+        Assert.Exact.AreEqual "   hi", "hi" ' FAILS
+        Debug.Print "test after assert"
+    End Sub
+End Module

From 76a30583f8c1c9607ab883bba72f538305a20215 Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 17:58:04 +0200
Subject: [PATCH 18/22] test: the add-in lanes state BETA 995 as well; 995's
 hover on a statement is empty, as 987's

---
 test/addin/appdata.test.mjs   | 2 +-
 test/addin/arch.test.mjs      | 2 +-
 test/addin/entry.test.mjs     | 2 +-
 test/addin/ideserver.test.mjs | 2 +-
 test/addin/keys.test.mjs      | 2 +-
 test/addin/panes.test.mjs     | 2 +-
 test/addin/reload.test.mjs    | 2 +-
 test/addin/symbols.test.mjs   | 4 ++--
 8 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/test/addin/appdata.test.mjs b/test/addin/appdata.test.mjs
index ba6bd90b..8f9bb5b7 100644
--- a/test/addin/appdata.test.mjs
+++ b/test/addin/appdata.test.mjs
@@ -9,7 +9,7 @@
 // That private APPDATA is what keeps the user's add-ins out of every other
 // lane, and these tests are what it rests on.
 //
-// Each test states what BETA 983 does. If one fails after an IDE update, the
+// Each test states what BETA 983 and 995 do. If one fails after an IDE update, the
 // IDE has changed: update P6 in WIP.HelpAddin.md and the lanes' APPDATA in
 // scripts/lib/tb-lane.mjs, and then this file.
 //
diff --git a/test/addin/arch.test.mjs b/test/addin/arch.test.mjs
index f6ab5bb5..06bf54d6 100644
--- a/test/addin/arch.test.mjs
+++ b/test/addin/arch.test.mjs
@@ -6,7 +6,7 @@
 // ArchProbeUser.dll. Every copy that loads prints one line: the bitness it was
 // built for, the executable of the process it runs in, and its own file.
 //
-// Each test states what BETA 983 does. If one fails after an IDE update, the
+// Each test states what BETA 983 and 995 do. If one fails after an IDE update, the
 // IDE has changed: update P7 in WIP.HelpAddin.md and the Add Ins page
 // (docs/IDE/AddIns/index.md), and then this file.
 //
diff --git a/test/addin/entry.test.mjs b/test/addin/entry.test.mjs
index aab8183e..02ca23b9 100644
--- a/test/addin/entry.test.mjs
+++ b/test/addin/entry.test.mjs
@@ -13,7 +13,7 @@
 // function called tbCreateCompilerAddin to tbCreateCompilerAddin_v3. This lane
 // checks both by what they do.
 //
-// Each test states what BETA 983 does. If one fails after an IDE update, the
+// Each test states what BETA 983 and 995 do. If one fails after an IDE update, the
 // IDE has changed: update P14 in WIP.HelpAddin.md, the entry point's NOTE on
 // the tbIDE package page (docs/Reference/Built-In/tbIDE/index.md) and the
 // messages on the Add Ins page (docs/IDE/AddIns/index.md), and then this file.
diff --git a/test/addin/ideserver.test.mjs b/test/addin/ideserver.test.mjs
index f555c4bd..99398b21 100644
--- a/test/addin/ideserver.test.mjs
+++ b/test/addin/ideserver.test.mjs
@@ -9,7 +9,7 @@
 // so a relative URL is a path below the ide folder. The page fetches each file
 // the way a frame's src would be resolved.
 //
-// Each test states what BETA 983 does. If one fails after an IDE update, the
+// Each test states what BETA 983 and 995 do. If one fails after an IDE update, the
 // IDE has changed: update P13 and "Offline" in WIP.HelpAddin.md, and then this
 // file.
 //
diff --git a/test/addin/keys.test.mjs b/test/addin/keys.test.mjs
index e1baab65..ca96b308 100644
--- a/test/addin/keys.test.mjs
+++ b/test/addin/keys.test.mjs
@@ -3,7 +3,7 @@
 // editor. The KeysProbe add-in (probes/keys) registers eight key strings and
 // prints "[KeysProbe] fired <key string>" to the DEBUG CONSOLE when one fires.
 //
-// Each test states what BETA 983 does. If one fails after an IDE update, the
+// Each test states what BETA 983 and 995 do. If one fails after an IDE update, the
 // IDE has changed: update P1 and P2 in WIP.HelpAddin.md, the NOTE on
 // docs/Reference/Built-In/tbIDE/KeyboardShortcuts.md and the entry in
 // BUGS-TO-REPORT.md, and then this file.
diff --git a/test/addin/panes.test.mjs b/test/addin/panes.test.mjs
index c2640014..abe3c280 100644
--- a/test/addin/panes.test.mjs
+++ b/test/addin/panes.test.mjs
@@ -11,7 +11,7 @@
 // The last test is what ToolWindows.Add does with windows given no id, which
 // P9 turned up.
 //
-// Each test states what BETA 983 does. If one fails after an IDE update, the
+// Each test states what BETA 983 and 995 do. If one fails after an IDE update, the
 // IDE has changed: update P3, P4 and P12 in WIP.HelpAddin.md and the tbIDE
 // pages that rest on them (HtmlElement, HtmlElementProperties, HtmlElements,
 // ToolWindow, ToolWindows), and then this file.
diff --git a/test/addin/reload.test.mjs b/test/addin/reload.test.mjs
index 61b3d277..6653e75a 100644
--- a/test/addin/reload.test.mjs
+++ b/test/addin/reload.test.mjs
@@ -10,7 +10,7 @@
 // Each also records in a file whether its Class_Terminate runs: the page ends
 // the compiler with taskkill /F (forceTerminate in main.js), so it cannot.
 //
-// Each test states what BETA 983 does. If one fails after an IDE update, the
+// Each test states what BETA 983 and 995 do. If one fails after an IDE update, the
 // IDE has changed: update P8 and P9 in WIP.HelpAddin.md, what the tbIDE
 // package page (docs/Reference/Built-In/tbIDE/index.md) says a compiler
 // restart does, and ToolWindows.Add's id on the ToolWindows page, and then
diff --git a/test/addin/symbols.test.mjs b/test/addin/symbols.test.mjs
index c5a66259..42253022 100644
--- a/test/addin/symbols.test.mjs
+++ b/test/addin/symbols.test.mjs
@@ -6,7 +6,7 @@
 // as the code editor's intellisense does (getLiveDebugIntellisenseMonaco).
 // Only page script can ask any of them; the add-in API has no such call.
 //
-// Each test states what BETA 983 and 987 do. If one fails after an IDE update, the
+// Each test states what BETA 983, 987 and 995 do. If one fails after an IDE update, the
 // IDE has changed: update P5 in WIP.HelpAddin.md, and the entry in
 // BUGS-TO-REPORT.md that the last hover test rests on, and then this file.
 //
@@ -125,7 +125,7 @@ scenario("P5: what the compiler says about the name under the cursor", (lane) =>
   test("hover on a variable gives its declaration, and on Debug.Print and a statement nothing", async () => {
     assert.equal(await hover(c, "c.Add", "c"), "*local variable* Dim c As Collection");
     assert.equal(await hover(c, "Nothing, count", "count"), "*parameter* ByVal count As Long");
-    // BETA 983 gives no hover here, and BETA 987 one whose text is empty.
+    // BETA 983 gives no hover here, and BETA 987 and 995 one whose text is empty.
     const nothing = [
       ["Debug.Print FindTheNeedle", "Debug"],
       ["Debug.Print FindTheNeedle", "Print"],

From 5076906357e8ef1cf5cf2219dea5103f45873220 Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 17:59:56 +0200
Subject: [PATCH 19/22] wip: the harness and add-in notes re-checked on BETA
 995; export's forward-slash failure exits 0

---
 BUGS-TO-REPORT.md |  3 ++-
 WIP.Harness.md    | 25 ++++++++++++----------
 WIP.HelpAddin.md  | 54 +++++++++++++++++++++++------------------------
 WIP.tbIDE.md      |  8 +++----
 4 files changed, 47 insertions(+), 43 deletions(-)

diff --git a/BUGS-TO-REPORT.md b/BUGS-TO-REPORT.md
index 33f0554a..4d4da183 100644
--- a/BUGS-TO-REPORT.md
+++ b/BUGS-TO-REPORT.md
@@ -534,7 +534,8 @@ file or folder does not exist.
 
 The echo line explains the first two: `exporting from "\\?\hello.twinproj"`. The project path
 is prefixed with `\\?\`, which turns off Windows' path normalisation, so only a full path with
-backslashes survives it. **What does not reproduce it:** `import`'s project path and the
+backslashes survives it. The forward-slashed folder ends `... FAILED`, creates nothing, and
+exits 0 (BETA 995), so a script sees success unless it reads the output. **What does not reproduce it:** `import`'s project path and the
 printing commands' take relative and forward-slashed paths, and with backslashes `export`
 creates every missing level of its output folder.
 
diff --git a/WIP.Harness.md b/WIP.Harness.md
index ee052367..e44c3b9c 100644
--- a/WIP.Harness.md
+++ b/WIP.Harness.md
@@ -26,16 +26,16 @@ compiler's `export` verb unpacks any of them without opening the IDE:
 "$TB/bin/twinBASIC_win32.exe" export "<some>.twinproj" "C:\out\dir\" --overwrite
 ```
 
-Against BETA 983 that yields **820 `.twin` files** --- 661 from the sixteen packages under
-`packages/`, 159 from the thirty-two sample and template projects under `projects/` and
-`addins/`. All of it is code the compiler accepts, which makes it the strongest available
-evidence for anything the documentation asserts about legal syntax.
+Against BETA 983 and 995 alike that yields **820 `.twin` files** --- 661 from the sixteen
+packages under `packages/`, 159 from the thirty-two sample and template projects under
+`projects/` (`addins/` holds no `.twinproj`). All of it is code the compiler accepts, which
+makes it the strongest available evidence for anything the documentation asserts about legal
+syntax.
 
 Two operational notes, both learned the annoying way. **Use backslashes.** A folder named
 with forward slashes fails with `output folder does not exist and could not be created`
-whether it exists or not. This note used to say that the folder must already exist and that
-only one level of it is created; measured against BETA 983, `export` given backslashes
-creates every missing level, three deep in the test. Its project path must also be a full
+whether it exists or not, creates nothing, and still exits 0. Given backslashes, `export`
+creates every missing level, three deep in the test (BETA 983 and 995). Its project path must also be a full
 one, because it is prefixed with `\\?\`. And **redirect stdin** when looping (`</dev/null`),
 or the executable consumes the loop's input and the second iteration never runs.
 
@@ -85,7 +85,8 @@ node scripts/census_attributes.mjs --attr Hidden          # one attribute
 node scripts/census_attributes.mjs --attr Hidden --dump-sites sites.json
 ```
 
-Against BETA 983: **661 files, 9,701 attribute sites, 55 distinct attributes**, and every
+Against BETA 995: **661 files, 9,713 attribute sites, 55 distinct attributes** (BETA 983
+gave 9,701 sites; 987 to 995 added a hidden VBA declare and a `[DispId]` on `QueryUnload`), and every
 one of the 55 is already in `Attributes.md` --- the "used but undocumented" section comes
 back empty. Sixteen documented attributes are used by no package, which is not a defect
 but does mean the census offers no evidence for those `Applicable to:` lines and a probe
@@ -532,7 +533,7 @@ Four smaller things it knows, each of which cost a run:
   comes straight after the `[BUILD] Executing` line, before the probe's first statement runs.
   The probe's `Debug.Cls` erases it, the probe prints what comes before the call and stops
   there, and `tbrun` used to exit 0 with that partial output (measured with and without
-  `Debug.Cls` on BETA 983). Since the tooling review's C25a, `tbrun` wraps the page's global
+  `Debug.Cls` on BETA 983 and 995: with it the probe prints exactly its lines, without it `tbrun` warns and the build log lines precede them, exit 0 either way). Since the tooling review's C25a, `tbrun` wraps the page's global
   `clearDebugConsole()` before it presses Build, and keeps what each clear erases
   (`keepClears` in `tb-ide-console.mjs`). A `BUILD_FAILED` line in that record after the last
   `[BUILD] Executing` line exits 2, naming the line and printing the partial output. `main.js`
@@ -813,10 +814,12 @@ exactly what the lane puts there. The compiler loads the DLLs in
 `%APPDATA%\twinBASIC\addins\<arch>` as well (P6), and the `APPDATA` each lane gives its
 IDEs keeps the user's out ([The add-in test runner](#the-add-in-test-runner)).
 
-**Measured, against BETA 983:**
+**Measured, against BETA 983 (and 995 where stated):**
 
 - **An IDE session writes nothing into its install.** A compile, a compiler crash and a
-  `tbrun` build-and-run each left all 233 files byte-identical, down to the mtimes. A
+  `tbrun` build-and-run each left all 233 files byte-identical, down to the mtimes; on
+  BETA 995 the install (235 files) was byte-identical after exports, a `tbbuild` and two
+  `tbrun` runs. A
   compile also left the per-user `%APPDATA%\twinBASIC` unchanged; that folder holds the
   user's downloaded packages and empty `addins`, `locale` and `themes` folders, and is
   shared by every install. So a compile's whole footprint outside its temp folders is the
diff --git a/WIP.HelpAddin.md b/WIP.HelpAddin.md
index 20de292f..87ff1b78 100644
--- a/WIP.HelpAddin.md
+++ b/WIP.HelpAddin.md
@@ -17,7 +17,7 @@ the detached HEAD of an old worktree keeps it --- so everything in it worth keep
 corrected, and nothing depends on it surviving. [What changed from the June
 draft](#what-changed-from-the-june-draft) lists the corrections.
 
-Facts about the IDE are from **BETA 983**. An offset like `main.js@611152` is a byte offset
+Facts about the IDE are from **BETA 983**, and were re-checked on BETA 995 where the text says so. An offset like `main.js@611152` is a byte offset
 into the one-line `ide/main.js`; offsets move with every build, so in any other build search
 for the quoted text instead. Each fact is one of three kinds:
 
@@ -70,7 +70,7 @@ the compiler what a symbol is.** Each of those gaps shapes a stage below.
   own environment, creates `packages`, `themes`, `locale`, `addins\win32` and
   `addins\win64` in, and returns. The page keeps the path as `commonFolderRootPath` and
   sends it with `RequestStartCompiler` and `RequestLoadAddins` (`main.js@1047705` and
-  `@1048667`). Measured on BETA 983 by
+  `@1048667`). Measured on BETA 983 and 995 by
   [test/addin/appdata.test.mjs](test/addin/appdata.test.mjs), with a probe add-in that
   prints the file it was loaded from: an IDE started with `APPDATA` naming a folder of the
   lane's own loaded the probe from `<APPDATA>\twinBASIC\addins\win32`, and not a second
@@ -107,7 +107,7 @@ the compiler what a symbol is.** Each of those gaps shapes a stage below.
   `shiftKeyDown` follows the keymap's `tbMisc_ShiftKeyStateDown` and `...Up` actions, so a
   test that presses Shift must not do it while a project is opening.
 - **The linker exports `tbCreateCompilerAddin` as `tbCreateCompilerAddin_v3`, and the
-  loader takes three names (P14).** Read in the compiler's code and measured on BETA 983 by
+  loader takes three names (P14).** Read in the compiler's code and measured on BETA 983 and 995 by
   [test/addin/entry.test.mjs](test/addin/entry.test.mjs). The loader --- in BETA 983 the
   code at `0x1EAB6275` in `twinBASIC_win32.dll`, and in another build the code that pushes
   the address of the string `tbCreateCompilerAddin_v2`, found with `dumpbin /disasm`; the
@@ -124,13 +124,13 @@ the compiler what a symbol is.** Each of those gaps shapes a stage below.
   `_v3` all loaded, and `_v4` did not, with `[EntryV4.dll] Failed to load addin.  Entry point
   not found.  Addin may have been compiled for a newer version of the twinBASIC IDE.` in the
   DEBUG CONSOLE and an `Unknown Addin` in the compiler's list. Both of P7's builds, win32 and
-  win64, exported `_v3` alone. Every install on this machine, BETA 947 to 983, has the same
+  win64, exported `_v3` alone. Every install on this machine, BETA 947 to 995, has the same
   three names in its loader, and each one's shipped Global Search add-in exports `_v3` alone,
   so both stamps are older than BETA 947.
 - **Add-ins cannot be switched off.** The Add-Ins menu lists the loaded add-ins with ticks,
   and every item calls `notSupportedMenuOption()` *(reported)*.
 - **A compiler restart loads every add-in again, from the file in its folder then (P9).**
-  Measured on BETA 983 by [test/addin/reload.test.mjs](test/addin/reload.test.mjs). A
+  Measured on BETA 983 and 995 by [test/addin/reload.test.mjs](test/addin/reload.test.mjs). A
   restart is the toolbar's restart button, every switch of the build target (below), and the
   IDE's own restart after a compiler crash. The page's `restartCompiler` (`main.js@153451`)
   first takes away what every add-in added: `removeAddinAlterations` removes their toolbar
@@ -162,7 +162,7 @@ the compiler what a symbol is.** Each of those gaps shapes a stage below.
   `addins\win64` alone. **Switching the target of an open project (Ctrl+F1 / Ctrl+F2)
   restarts the compiler in the other bitness, and the new one loads the other folders.**
   `changedActiveBuildConfig` in `ide/main2.js` records the new target and kills the
-  compiler. Measured on BETA 983 by [test/addin/arch.test.mjs](test/addin/arch.test.mjs),
+  compiler. Measured on BETA 983 and 995 by [test/addin/arch.test.mjs](test/addin/arch.test.mjs),
   with a 32-bit and a 64-bit build of a probe in both folders of their bitness, the install's
   and `%APPDATA%`'s: the project opened in win32, whose compiler loaded the two 32-bit copies
   alone; a switch to win64 started `twinBASIC_win64_noDEP.exe`, which loaded the two 64-bit
@@ -173,7 +173,7 @@ the compiler what a symbol is.** Each of those gaps shapes a stage below.
 
 ### Keyboard shortcuts
 
-Read at `main.js@608242`, `@610953` and `@611152`, and measured on BETA 983 by P1 and P2,
+Read at `main.js@608242`, `@610953` and `@611152`, and measured on BETA 983 and 995 by P1 and P2,
 whose lane is [test/addin/keys.test.mjs](test/addin/keys.test.mjs).
 
 - `KeyboardShortcuts.Add` lowercases the key string, deletes its whitespace and stores it
@@ -216,7 +216,7 @@ whose lane is [test/addin/keys.test.mjs](test/addin/keys.test.mjs).
 ### Tool windows
 
 Read at `main.js@1002292` (`toolWindowElementAddChild`) and `@1005960`
-(`toolWindowElementSetProperty`), and measured on BETA 983 by P3, P4 and P12, whose lane is
+(`toolWindowElementSetProperty`), and measured on BETA 983 and 995 by P3, P4 and P12, whose lane is
 [test/addin/panes.test.mjs](test/addin/panes.test.mjs).
 
 - **A tool window is part of the main document**, inside an open shadow root, not an iframe.
@@ -231,7 +231,7 @@ Read at `main.js@1002292` (`toolWindowElementAddChild`) and `@1005960`
   `createToolWindow` (`main.js@992211`) files a window under the second argument of
   `ToolWindows.Add`, and `createToolWindowById` returns the window the page already has
   under that id, with its body emptied, rather than a new one; the add-in's new `ToolWindow`
-  is then bound to it, since the page answers with its number. Measured on BETA 983: P9's
+  is then bound to it, since the page answers with its number. Measured on BETA 983 and 995: P9's
   window given no id was under `""`, and the last test of
   [panes.test.mjs](test/addin/panes.test.mjs) opened two windows given no id and got one,
   titled by the second, holding the second's element and what was then added through the
@@ -295,7 +295,7 @@ Read at `main.js@1002292` (`toolWindowElementAddChild`) and `@1005960`
 1. **The external browser.** `ShellExecuteW` from the add-in DLL. Certain to work; it leaves
    the IDE. The IDE itself opens links with `hostAppObject.Shell('cmd.exe /c start "link"
    "'+url+'"',1)` *(reported)* --- a host object that only page script can reach.
-2. **An `iframe` in a tool window --- it works (P3, BETA 983).** Nothing refuses the tag. No
+2. **An `iframe` in a tool window --- it works (P3, BETA 983 and 995).** Nothing refuses the tag. No
    file under `ide\` sets a Content-Security-Policy --- there is no
    `Content-Security-Policy`, `http-equiv` or `frame-ancestors` in any `ide\*.htm` --- and
    neither does the compiler's HTTP header template *(reported)*. The host DLL,
@@ -341,7 +341,7 @@ Read at `main.js@1002292` (`toolWindowElementAddChild`) and `@1005960`
 **Offline** is harder. `_site-offline/` works over `file://`, and a page served from
 `http://localhost` cannot frame a `file://` URL. The options are `srcdoc` with rewritten
 links, or files under the IDE's `ide\` folder. **The IDE serves any file placed there (P13,
-BETA 983)**, measured by [test/addin/ideserver.test.mjs](test/addin/ideserver.test.mjs)
+BETA 983 and 995)**, measured by [test/addin/ideserver.test.mjs](test/addin/ideserver.test.mjs)
 with files put in a lane's copy of the install:
 
 - The server is the page server, `bin\twinBASIC_win32.exe --ide=<pid>`, not the compiler:
@@ -372,7 +372,7 @@ have: writing into the install, which every new build replaces. Still deferred.
   4](#stage-4-the-add-in-in-increments)) and, for context, its own parser of the project's
   source.
 - **The compiler knows, and names the package, the container and the kind (P5).** Measured
-  on BETA 983 by [test/addin/symbols.test.mjs](test/addin/symbols.test.mjs), which puts each
+  on BETA 983 and 995 by [test/addin/symbols.test.mjs](test/addin/symbols.test.mjs), which puts each
   question the way the IDE's own code does. Hover (`textDocument/hover`, `main.js@842393`)
   returns markdown: for a procedure, its declaration, then a heading naming where it is
   declared, then its `[Description]` text, which for a VBA function is several paragraphs:
@@ -391,7 +391,7 @@ have: writing into the install, which every new build replaces. Still deferred.
   says `*class* **Collection** ... in package VBA` and lists `*[default]* VBA._Collection`.
   A variable gives its declaration, `*local variable* Dim c As Collection`. `Debug`,
   `Debug.Print` and a statement such as `Dim` give nothing, and a type such as `Long` a line
-  about it. BETA 983 gives no hover for those three, and BETA 987 a hover whose text is
+  about it. BETA 983 gives no hover for those three, and BETA 987 and 995 a hover whose text is
   empty, so the add-in must treat both as nothing. Over a procedure's name in its own declaration, hover gives a debug block
   instead, `TB-DEBUG CODEGEN SIZE: [NOT-READY]`; over a `ByVal` parameter of a class,
   `String`, `Variant` or `Object` it adds a wrong note about `Option Explicit`
@@ -449,7 +449,7 @@ have: writing into the install, which every new build replaces. Still deferred.
   1](#stage-1-testing-add-ins-by-machine) fixes this for every harness tool, not only for
   add-in tests.
 - **The `.twinproj` association** is `HKCU\Software\Classes\.twinproj` →
-  `twinBASIC.ProjectFile`, and it currently points at the BETA 983 `twinBASIC.exe`. A
+  `twinBASIC.ProjectFile`, and it currently points at the newest install's (BETA 995) `twinBASIC.exe`. A
   harvested finding said every launch re-registers it. Key timestamps say otherwise:
   `DefaultIcon` and `shell\open\command` were last written when BETA 983 was installed, and
   a day of launches of that build did not touch them. **The IDE rewrites them when its path
@@ -703,20 +703,20 @@ WebView2 preferring light.
 
 | # | Question | What it decides |
 |---|---|---|
-| P1 | Do `{ctrl}` and `{alt}` add-in shortcuts ever fire? Register `{ctrl}{shift}d`, `{alt}f`, `{shift}d`, `d` and `f1`, and press each. **Answered, BETA 983: no.** `d`, `{shift}d`, `f1` and `{shift}f1` fire; `{ctrl}{shift}d`, `{ctrl}d` and `{alt}f` fire only when the same key was pressed on its own less than 500 ms before. Queued in BUGS-TO-REPORT.md; the KeyboardShortcuts page has a NOTE. | the bug report; which key the add-in uses; the NOTE on the KeyboardShortcuts page |
-| P2 | Does the add-in's `f1` fire with focus in the code editor, and what happens with signature help showing? **Answered, BETA 983: yes.** It fires with the focus in the code editor, in the DEBUG CONSOLE and on nothing, and types nothing. With signature help showing, the IDE expands or collapses it as well, and logs `command failed: "tbHelp_ToggleExpandSignatureHelp"`. | F1 or another key --- F1 |
-| P3 | Does an `iframe` of a documentation page load and navigate inside a tool window? Size, scrolling, theme. **Answered, BETA 983: yes.** It loads, follows its own links, moves when the add-in sets `src`, scrolls, and fills the window under a wrapper's flex layout; the live site works too. Keys in the frame never reach the add-in, and the page's colour scheme is Windows', not the IDE's. | how pages are shown --- in the pane |
-| P4 | Does `innerHTML` render, and do inline handlers in it run page script? **Answered, BETA 983: yes, and yes.** It renders, and its inline handlers run as the IDE page's own script --- an `<img>`'s `onerror` with nothing clicked --- with its globals in reach. A property whose name starts with `on` is dropped, and the add-in hears no error. | how summaries are drawn; whether the page-internals route exists --- it does |
-| P5 | What does hover return for `MsgBox`, `Collection.Add`, `ToolWindows.Add` and a symbol declared in the project? What does definition return for a package symbol? **Answered, BETA 983:** hover gives the declaration, which says the kind, then a heading naming where it is declared: `in VBA.Interaction`, `in VBA._Collection`, `in tbIDE.IToolWindowsV1`, `in SymbolsProbe.Symbols` --- a class's members by its default interface, not by the class's name. Definition gives the declaration in the package's own source, `.../Packages/VBA/Sources/Interaction.twin`, which the IDE opens. Nothing for `Debug.Print` or a statement. Only page script can ask. | compiler-assisted context is possible; which route is [Stage 4](#stage-4-the-add-in-in-increments), increment 3 |
-| P6 | Does the compiler also load add-ins from `%APPDATA%\twinBASIC\addins\<arch>`? This needs a DLL placed there for a moment, and the user's own IDE would load it too --- **ask before running it.** **Answered, BETA 983: yes**, from `addins\win32` there and not from `addins` itself. The page expands `%APPDATA%` in the IDE's environment and sends the folder, and the compiler loads from what it is sent. Measured with `APPDATA` pointed at a folder of the lane's own, so no DLL went in the user's. | harness isolation --- every lane IDE gets an `APPDATA` of its own |
-| P7 | Which bitness does the compiler start in, and does switching the build target restart it in the other one and load the other `addins` folder? **Answered, BETA 983: yes, and yes.** The target a project opens in picks the compiler --- win32 when the IDE remembers none, `twinBASIC_win64_noDEP.exe` for a project remembered as win64 --- and each compiler loads the folders of its own bitness alone, the install's and `%APPDATA%`'s. Switching the target of an open project restarts the compiler in the other bitness, and the new one loads the other folders: a 64-bit build of the probe in each win64 folder loaded, and ran 64-bit, once the project was switched to win64, and the 32-bit ones again after a switch back. | building and testing both bitnesses --- `buildAddin` builds either, and a shipped add-in needs both |
-| P8 | Is a loaded add-in DLL locked against being overwritten? **Answered, BETA 983: yes.** While its IDE runs, overwriting fails (`EBUSY`) and deleting fails (`EPERM`), though renaming works; the hold outlasts the compiler's exit by a few tens of milliseconds. The P9 lane checks all three again. | the rebuild loop --- the DLL is built outside `addins`, and copied in once the IDE has ended, or renamed aside first (P9) |
-| P9 | Does a compiler restart reload add-ins from disk? **Answered, BETA 983: yes.** A restart --- the restart button, a switch of build target, or the IDE's own after a crash --- removes every add-in's buttons and shortcuts, leaves its windows showing `(currently unavailable)`, kills the old compiler, so that no `Class_Terminate` runs, and starts a compiler that loads whatever file is in the folders then. With the loaded DLL renamed aside, a restart loaded nothing; with a new build put in its place, the next restart loaded it, about a second after the click, and it got its old windows back by their ids. | a rebuild loop without restarting the IDE --- it works: rename aside, copy in, restart |
+| P1 | Do `{ctrl}` and `{alt}` add-in shortcuts ever fire? Register `{ctrl}{shift}d`, `{alt}f`, `{shift}d`, `d` and `f1`, and press each. **Answered, BETA 983 and 995: no.** `d`, `{shift}d`, `f1` and `{shift}f1` fire; `{ctrl}{shift}d`, `{ctrl}d` and `{alt}f` fire only when the same key was pressed on its own less than 500 ms before. Queued in BUGS-TO-REPORT.md; the KeyboardShortcuts page has a NOTE. | the bug report; which key the add-in uses; the NOTE on the KeyboardShortcuts page |
+| P2 | Does the add-in's `f1` fire with focus in the code editor, and what happens with signature help showing? **Answered, BETA 983 and 995: yes.** It fires with the focus in the code editor, in the DEBUG CONSOLE and on nothing, and types nothing. With signature help showing, the IDE expands or collapses it as well, and logs `command failed: "tbHelp_ToggleExpandSignatureHelp"`. | F1 or another key --- F1 |
+| P3 | Does an `iframe` of a documentation page load and navigate inside a tool window? Size, scrolling, theme. **Answered, BETA 983 and 995: yes.** It loads, follows its own links, moves when the add-in sets `src`, scrolls, and fills the window under a wrapper's flex layout; the live site works too. Keys in the frame never reach the add-in, and the page's colour scheme is Windows', not the IDE's. | how pages are shown --- in the pane |
+| P4 | Does `innerHTML` render, and do inline handlers in it run page script? **Answered, BETA 983 and 995: yes, and yes.** It renders, and its inline handlers run as the IDE page's own script --- an `<img>`'s `onerror` with nothing clicked --- with its globals in reach. A property whose name starts with `on` is dropped, and the add-in hears no error. | how summaries are drawn; whether the page-internals route exists --- it does |
+| P5 | What does hover return for `MsgBox`, `Collection.Add`, `ToolWindows.Add` and a symbol declared in the project? What does definition return for a package symbol? **Answered, BETA 983 and 995:** hover gives the declaration, which says the kind, then a heading naming where it is declared: `in VBA.Interaction`, `in VBA._Collection`, `in tbIDE.IToolWindowsV1`, `in SymbolsProbe.Symbols` --- a class's members by its default interface, not by the class's name. Definition gives the declaration in the package's own source, `.../Packages/VBA/Sources/Interaction.twin`, which the IDE opens. Nothing for `Debug.Print` or a statement. Only page script can ask. | compiler-assisted context is possible; which route is [Stage 4](#stage-4-the-add-in-in-increments), increment 3 |
+| P6 | Does the compiler also load add-ins from `%APPDATA%\twinBASIC\addins\<arch>`? This needs a DLL placed there for a moment, and the user's own IDE would load it too --- **ask before running it.** **Answered, BETA 983 and 995: yes**, from `addins\win32` there and not from `addins` itself. The page expands `%APPDATA%` in the IDE's environment and sends the folder, and the compiler loads from what it is sent. Measured with `APPDATA` pointed at a folder of the lane's own, so no DLL went in the user's. | harness isolation --- every lane IDE gets an `APPDATA` of its own |
+| P7 | Which bitness does the compiler start in, and does switching the build target restart it in the other one and load the other `addins` folder? **Answered, BETA 983 and 995: yes, and yes.** The target a project opens in picks the compiler --- win32 when the IDE remembers none, `twinBASIC_win64_noDEP.exe` for a project remembered as win64 --- and each compiler loads the folders of its own bitness alone, the install's and `%APPDATA%`'s. Switching the target of an open project restarts the compiler in the other bitness, and the new one loads the other folders: a 64-bit build of the probe in each win64 folder loaded, and ran 64-bit, once the project was switched to win64, and the 32-bit ones again after a switch back. | building and testing both bitnesses --- `buildAddin` builds either, and a shipped add-in needs both |
+| P8 | Is a loaded add-in DLL locked against being overwritten? **Answered, BETA 983 and 995: yes.** While its IDE runs, overwriting fails (`EBUSY`) and deleting fails (`EPERM`), though renaming works; the hold outlasts the compiler's exit by a few tens of milliseconds. The P9 lane checks all three again. | the rebuild loop --- the DLL is built outside `addins`, and copied in once the IDE has ended, or renamed aside first (P9) |
+| P9 | Does a compiler restart reload add-ins from disk? **Answered, BETA 983 and 995: yes.** A restart --- the restart button, a switch of build target, or the IDE's own after a crash --- removes every add-in's buttons and shortcuts, leaves its windows showing `(currently unavailable)`, kills the old compiler, so that no `Class_Terminate` runs, and starts a compiler that loads whatever file is in the folders then. With the loaded DLL renamed aside, a restart loaded nothing; with a new build put in its place, the next restart loaded it, about a second after the click, and it got its old windows back by their ids. | a rebuild loop without restarting the IDE --- it works: rename aside, copy in, restart |
 | P10 | Does an environment variable set by the harness reach the add-in (`Environ$`)? **Answered, BETA 983: yes**, through the launcher, the IDE and the compiler the IDE starts. With `TB_ADDIN_TEST=1` in `launchIde`'s environment, `Environ$` and `GetEnvironmentVariableW` both returned `1` in the add-in, and a compiler started by the restart button returned it too; left out, both said it was unset. `WEBVIEW2_USER_DATA_FOLDER`, which `launchIde` always sets, arrived with the lane's port in it. | the side-effect switch |
-| P11 | Does the IDE write into its own install folder during a session? **Answered, BETA 983: no.** A compile, a compiler crash and a `tbrun` build-and-run left all 233 files byte-identical, mtimes included. | hardlinks or copies --- copies, for safety, at 380 ms |
-| P12 | Does `raiseEvent` from plain tool-window HTML throw? **Answered, BETA 983: yes** --- `TypeError: Cannot read properties of null (reading 'rootEventHandler')`, and the listener is not called. An inline handler that calls the listener `AddEventListener` stored on its parent, `this.parentNode.<name>(event)`, reaches the add-in. | how the pane's events are written |
-| P13 | Does the compiler's HTTP server serve any file placed under `ide\`? **Answered, BETA 983: yes**, and it is the page server, `twinBASIC_win32.exe --ide=<pid>`, not the compiler. Any file, byte for byte, below the page's passkey path, including one written after the IDE started; a frame with a relative `src` shows it on the IDE page's own origin. A query string makes a 404, and `.html` has no `Content-Type`. | an offline route --- it exists ([Offline](#ways-to-show-a-page)) |
-| P14 | What do `tbCreateCompilerAddin_v2` and `_v3` expect? **Answered, BETA 983: what `tbCreateCompilerAddin` does.** The loader looks for the plain name, then `_v2`, then `_v3`, and calls whichever it finds with the `Host` alone and asks the result for `IAddInV1`. The names are version stamps: the linker exports a function named `tbCreateCompilerAddin` as `tbCreateCompilerAddin_v3` alone, and an IDE that knows none of a DLL's names refuses it as `compiled for a newer version of the twinBASIC IDE`, as a patched `_v4` was. | nothing in the design --- the add-in declares `tbCreateCompilerAddin` as the package says; the tbIDE page has a NOTE |
+| P11 | Does the IDE write into its own install folder during a session? **Answered, BETA 983 and 995: no.** On 983 a compile, a compiler crash and a `tbrun` build-and-run left all 233 files byte-identical, mtimes included. On 995 the install (235 files) was byte-identical after exports, a `tbbuild` and two `tbrun` runs; `%APPDATA%` was not re-checked. | hardlinks or copies --- copies, for safety, at 380 ms |
+| P12 | Does `raiseEvent` from plain tool-window HTML throw? **Answered, BETA 983 and 995: yes** --- `TypeError: Cannot read properties of null (reading 'rootEventHandler')`, and the listener is not called. An inline handler that calls the listener `AddEventListener` stored on its parent, `this.parentNode.<name>(event)`, reaches the add-in. | how the pane's events are written |
+| P13 | Does the compiler's HTTP server serve any file placed under `ide\`? **Answered, BETA 983 and 995: yes**, and it is the page server, `twinBASIC_win32.exe --ide=<pid>`, not the compiler. Any file, byte for byte, below the page's passkey path, including one written after the IDE started; a frame with a relative `src` shows it on the IDE page's own origin. A query string makes a 404, and `.html` has no `Content-Type`. | an offline route --- it exists ([Offline](#ways-to-show-a-page)) |
+| P14 | What do `tbCreateCompilerAddin_v2` and `_v3` expect? **Answered, BETA 983 and 995: what `tbCreateCompilerAddin` does.** The loader looks for the plain name, then `_v2`, then `_v3`, and calls whichever it finds with the `Host` alone and asks the result for `IAddInV1`. The names are version stamps: the linker exports a function named `tbCreateCompilerAddin` as `tbCreateCompilerAddin_v3` alone, and an IDE that knows none of a DLL's names refuses it as `compiled for a newer version of the twinBASIC IDE`, as a patched `_v4` was. | nothing in the design --- the add-in declares `tbCreateCompilerAddin` as the package says; the tbIDE page has a NOTE |
 
 ### Stage 3: the symbol index, generated by the docs build
 
diff --git a/WIP.tbIDE.md b/WIP.tbIDE.md
index 14900422..29eeaa54 100644
--- a/WIP.tbIDE.md
+++ b/WIP.tbIDE.md
@@ -27,7 +27,7 @@ End Module
 
 The returned object must implement the [`AddIn`](#public-user-facing-surface) interface (a single read-only `Name` property, declared in `Addin.twin`). Every sample uses this exact `tbCreateCompilerAddin` skeleton — surface it on the index landing as the canonical entry point.
 
-Two things about loading were measured on BETA 983 (P9 and P14 in [WIP.HelpAddin.md](WIP.HelpAddin.md)), and the index page says both:
+Two things about loading were measured on BETA 983 and 995 (P9 and P14 in [WIP.HelpAddin.md](WIP.HelpAddin.md)), and the index page says both:
 
 - **The linker exports `tbCreateCompilerAddin` as `tbCreateCompilerAddin_v3`**, and under no other name. The IDE's loader accepts `tbCreateCompilerAddin`, `_v2` and `_v3`, calls each the same way, and refuses a DLL with none of them as *compiled for a newer version of the twinBASIC IDE*. The suffix is a version stamp, not a different signature.
 - **A compiler restart does not release the object; it kills it.** The addin lives in the compiler's process, and the page ends that process with `taskkill /F` (`forceTerminate` in `main.js`) on every compiler restart --- the restart button, a switch of build target, a crash --- so `Class_Terminate` does not run, and a new instance is loaded from the DLL on disk. Closing the project calls `forceTerminate` as well *(read, not measured)*. This note used to say the object is released "when the addin is disabled or the IDE shuts down"; the Add-Ins menu's items cannot disable one *(reported)*, and the index page repeated the claim until the P9 lane showed `Class_Terminate` not running.
@@ -112,7 +112,7 @@ Three things make this surface unusual and have to be surfaced on the docs:
 2. **The custom-element tags.** `HtmlElements.Add(id, tagName)` accepts standard HTML tags (`"div"`, `"input"`, `"span"`, `"h1"`, …) AND four IDE-specific widget tags: `"chartjs"` (Chart.js wrapper — surfaces a `.chart` property), `"monaco"` (the Monaco editor — surfaces a `.editor` property), `"listview"` (the IDE's listview widget — surfaces a `.listview` property with `addItem` / `removeItem` / etc.), and `"virtuallistview"` (the same with `setItemCount` + the `onAsyncGetItemHTML` event). All four are demonstrated in samples 11–14. Surface as *"the tag name is forwarded to the IDE's tool-window renderer, which understands the standard HTML tags plus the custom widget tags … see sample 11 / 12 / 13 / 14"*.
 3. **`AddEventListener(DomEventName As String, CallbackFunc As LongPtr, Optional Data As Variant)`.** The callback is passed as `AddressOf SomeSub`, and `SomeSub` must have the signature `Sub(ByVal eventInfo As HtmlEventProperties)`. The `eventInfo` parameter is the IDE-marshalled equivalent of the JavaScript `Event` object — `eventInfo.key` / `eventInfo.target.value` / `eventInfo.target.id` are the usual fields, but again the property names are resolved against the *actual* event object at run time, not declared statically. Sample 13 also demonstrates **custom event names raised from inline HTML** via the IDE-side `raiseEvent("name", event, stopPropagation, …customData)` JavaScript helper; the custom-data values become `eventInfo.customData0`, `eventInfo.customData1`, … and are demonstrated in sample 15's `ClickedMatch` handler. Sample 14 demonstrates **async events** via `eventInfo.setAsyncResult("<html>")` (the listener returns the requested HTML asynchronously back into the virtual list view's render cycle).
 
-**`raiseEvent` is narrower than item 3 suggests** (P12 in [WIP.HelpAddin.md](WIP.HelpAddin.md), measured on BETA 983): it works only inside a `listview` / `virtuallistview` or an `AddMonacoWidget` widget, and from plain tool-window HTML it throws a `TypeError` in the IDE's page. P4 measured the rest of this surface: `innerHTML`'s inline handlers run as the IDE page's own script, and a property whose name starts with `on` is dropped without an error. The HtmlElement and HtmlElementProperties pages say all three; the ToolWindow page says that showing a window resets its root's `display`.
+**`raiseEvent` is narrower than item 3 suggests** (P12 in [WIP.HelpAddin.md](WIP.HelpAddin.md), measured on BETA 983, the `TypeError` on 995 as well): it works only inside a `listview` / `virtuallistview` or an `AddMonacoWidget` widget, and from plain tool-window HTML it throws a `TypeError` in the IDE's page. P4 measured the rest of this surface: `innerHTML`'s inline handlers run as the IDE page's own script, and a property whose name starts with `on` is dropped without an error. The HtmlElement and HtmlElementProperties pages say all three; the ToolWindow page says that showing a window resets its root's `display`.
 
 Document the four `Html*` classes as the *contract* (`Item` default member, the `Value` accessor, the `Properties` chaining) and use the samples to illustrate the dynamic-resolution mechanism. Do not try to enumerate the resolved property surface — it's open-ended.
 
@@ -209,9 +209,9 @@ Surface as the canonical safe-cast pattern on `CodeEditor.md`.
 
 ## `KeyboardShortcuts.Add` callback signature
 
-The `keyString` argument is a literal key with optional `{CTRL}` / `{SHIFT}` / `{ALT}` prefixes, e.g. `"{CTRL}{SHIFT}d"` (the source-side `[Description]`'s example). The `Callback` is `AddressOf` an addin function; the function takes no arguments and returns nothing --- a `Private Sub` with no parameters, in the add-in's class, works (measured, BETA 983).
+The `keyString` argument is a literal key with optional `{CTRL}` / `{SHIFT}` / `{ALT}` prefixes, e.g. `"{CTRL}{SHIFT}d"` (the source-side `[Description]`'s example). The `Callback` is `AddressOf` an addin function; the function takes no arguments and returns nothing --- a `Private Sub` with no parameters, in the add-in's class, works (measured, BETA 983 and 995).
 
-**The source's own example does not fire.** No sample uses `KeyboardShortcuts.Add`, so it was measured instead: P1 and P2 in [WIP.HelpAddin.md](WIP.HelpAddin.md), with the lane `test/addin/keys.test.mjs`. In BETA 983 a shortcut with `{CTRL}` or `{ALT}` never fires when pressed, the prefixes must come in the order `{ctrl}{shift}{alt}`, a shortcut fires on key-up wherever the focus is in the IDE's window, and a key that types fires each time it is typed. The published page says all of that, with an example on Shift+F12; keep it in step with the lane.
+**The source's own example does not fire.** No sample uses `KeyboardShortcuts.Add`, so it was measured instead: P1 and P2 in [WIP.HelpAddin.md](WIP.HelpAddin.md), with the lane `test/addin/keys.test.mjs`. In BETA 983 and 995 a shortcut with `{CTRL}` or `{ALT}` never fires when pressed, the prefixes must come in the order `{ctrl}{shift}{alt}`, a shortcut fires on key-up wherever the focus is in the IDE's window, and a key that types fires each time it is typed. The published page says all of that, with an example on Shift+F12; keep it in step with the lane.
 
 **Do not describe callbacks as running "on the IDE's UI thread".** This file used to say to, and it is unmeasured and probably misleading: an add-in runs inside the compiler's process (P10), not in the IDE's page, which is a WebView2 process of its own. The KeyboardShortcuts page no longer says it. **The AddinTimer page still does**, three times, with "long-running work ... will block the UI thread" --- unverified; which thread runs an add-in's callbacks, and what a slow one holds up, is not known. Fix it when something measures it.
 

From 81c99ea1f16244cc1f0477c64b77cdfe7280235b Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 18:48:07 +0200
Subject: [PATCH 20/22] docs: As New needs a no-argument constructor (TB5121);
 984's FileCopy, Line Input, ReDim, #Const fixes

---
 docs/Features/Advanced/Classes-and-Modules.md     | 1 +
 docs/Features/Language/Inheritance.md             | 2 +-
 docs/Reference/Attributes.md                      | 2 +-
 docs/Reference/Compiler Constants.md              | 2 ++
 docs/Reference/Core/Line-Input.md                 | 2 ++
 docs/Reference/Core/New.md                        | 2 +-
 docs/Reference/Core/ReDim.md                      | 2 ++
 docs/Reference/Core/Topic-Preprocessor.md         | 2 ++
 docs/Reference/Default/VBA/FileSystem/FileCopy.md | 3 +++
 9 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/docs/Features/Advanced/Classes-and-Modules.md b/docs/Features/Advanced/Classes-and-Modules.md
index bdf87dc7..925f0cf3 100644
--- a/docs/Features/Advanced/Classes-and-Modules.md
+++ b/docs/Features/Advanced/Classes-and-Modules.md
@@ -16,6 +16,7 @@ A class can have a `Sub New` constructor, and the constructor can take arguments
 - `New MyClass(123)` runs `Sub New(Value As Long)`. `Class_Initialize` is not raised.
 - In a class that also has a `Class_Initialize`, a plain `New MyClass` runs `Class_Initialize`. `Sub New` does not run.
 - A class that has both a `Class_Initialize` and a `Sub New` with no parameters cannot be created with a plain `New`. The call matches both, and fails with TB5073.
+- A class whose only `Sub New` takes arguments, with no `Class_Initialize`, cannot be declared [`As New`](../../tB/Core/New), which creates the object without arguments. The declaration fails with TB5121. This holds even when every argument is `Optional`.
 
 ### Example
 
diff --git a/docs/Features/Language/Inheritance.md b/docs/Features/Language/Inheritance.md
index 49e3b2ef..bb81c709 100644
--- a/docs/Features/Language/Inheritance.md
+++ b/docs/Features/Language/Inheritance.md
@@ -60,7 +60,7 @@ This option supports full inheritance and OOP: `Protected` methods and variables
 ### Example: Animal Class Hierarchy
 
 > [!IMPORTANT]
-> Every class in this example is declared `Private Class`, because each one has a `Sub New` that takes arguments. A class that is not `Private` is exposed to COM, and COM creates objects without arguments. So a public class --- base or derived --- whose `Sub New` takes arguments fails to compile with TB5135, unless it also has a constructor that takes none. There are three fixes: declare the class `Private`, add the `[COMCreatable(False)]` attribute, or add a constructor without arguments, such as `Class_Initialize`. See [Parameterized Class Constructors](../Advanced/Classes-and-Modules#parameterized-class-constructors).
+> Every class in this example is declared `Private Class`, because each one has a `Sub New` that takes arguments. A class that is not `Private` is exposed to COM, and COM creates objects without arguments. So a public class --- base or derived --- whose `Sub New` takes arguments fails to compile with TB5135, unless it also has a constructor that takes none. There are three fixes: declare the class `Private`, add the `[COMCreatable(False)]` attribute, or add a constructor without arguments, such as `Class_Initialize`. Only the third lets the class be declared `As New`; without it, `As New` fails with TB5121. See [Parameterized Class Constructors](../Advanced/Classes-and-Modules#parameterized-class-constructors).
 
 Starting with a base class:
 
diff --git a/docs/Reference/Attributes.md b/docs/Reference/Attributes.md
index cf238d20..9f02067f 100644
--- a/docs/Reference/Attributes.md
+++ b/docs/Reference/Attributes.md
@@ -160,7 +160,7 @@ Syntax: **[COMCreatable** [ **( True** \| **False )** ] **]**
 
 Applicable to:  [**Class**](Class), [**CoClass**](CoClass)
 
-Indicates whether the class can be created through COM. It does not govern [**New**](New) inside the project: a `[COMCreatable(False)]` class is created with **New** as usual. A COM-creatable class needs a constructor that takes no arguments, so a class whose only `Sub New` takes arguments fails with TB5135 --- *error generating implicit default constructor ... (for COM exposure)* --- unless it is marked `[COMCreatable(False)]`, is **Private**, or has a constructor without arguments as well. See [Parameterized Class Constructors](../../Features/Advanced/Classes-and-Modules#parameterized-class-constructors).
+Indicates whether the class can be created through COM. It does not govern [**New**](New) inside the project: a `[COMCreatable(False)]` class is created with **New** as usual. A COM-creatable class needs a constructor that takes no arguments, so a class whose only `Sub New` takes arguments fails with TB5135 --- *error generating implicit default constructor ... (for COM exposure)* --- unless it is marked `[COMCreatable(False)]`, is **Private**, or has a constructor without arguments as well. The first two fixes leave the class with no constructor that takes no arguments, so it still cannot be declared [**As New**](New): that fails with TB5121. See [Parameterized Class Constructors](../../Features/Advanced/Classes-and-Modules#parameterized-class-constructors).
 
 ## ComExport  (optional Bool)
 {: #comexport }
diff --git a/docs/Reference/Compiler Constants.md b/docs/Reference/Compiler Constants.md
index fd8aa6fd..476ca424 100644
--- a/docs/Reference/Compiler Constants.md	
+++ b/docs/Reference/Compiler Constants.md	
@@ -15,6 +15,8 @@ The list includes the constants that VBA documents, even those twinBASIC does no
 
 ## Predefined constants
 
+Each value below is the one a module sees unless it redefines the constant. `#Const` can redefine any of them, and the new value applies only in the module that declares it: after `#Const Win32 = 0`, `#If Win32` is false in that module and still true everywhere else. See [Predefined compiler constants](../tB/Core/Topic-Preprocessor#predefined-compiler-constants).
+
 ### `Win16`
 
 **Purpose:** Indicates a 16-bit Windows compatible platform.\
diff --git a/docs/Reference/Core/Line-Input.md b/docs/Reference/Core/Line-Input.md
index c7aadb22..93f9ecff 100644
--- a/docs/Reference/Core/Line-Input.md
+++ b/docs/Reference/Core/Line-Input.md
@@ -22,6 +22,8 @@ Data read with **Line Input #** is usually written to a file with [**Print #**](
 
 The **Line Input #** statement reads from a file one character at a time until it encounters a carriage return (**Chr**(13)) or carriage return-linefeed (**Chr**(13) + **Chr**(10)) sequence. Carriage return-linefeed sequences are skipped rather than appended to the character string.
 
+Reading past the last line of the file raises run-time error 62 (*Input past end of file*), and leaves *varname* unchanged. Test for the end of the file with [**EOF**](../Modules/FileSystem/EOF) before each read.
+
 ### Example
 
 This example uses the **Line Input #** statement to read a line from a sequential file and assign it to a variable. This example assumes that `TESTFILE` is a text file with a few lines of sample data.
diff --git a/docs/Reference/Core/New.md b/docs/Reference/Core/New.md
index 8667cd78..cd70f728 100644
--- a/docs/Reference/Core/New.md
+++ b/docs/Reference/Core/New.md
@@ -28,7 +28,7 @@ Syntax:
 : A class name or other creatable object type. **New** can't be used to create new instances of any intrinsic data type (such as **Long** or **String**), and can't be used to create dependent objects.
 
 *arglist*
-: *optional* (twinBASIC) The arguments passed to the class's **Sub New** constructor, separated by commas --- `New Dog("Rex")`. The class must declare a **Sub New** whose parameters match; see [Parameterized Class Constructors](../../Features/Advanced/Classes-and-Modules#parameterized-class-constructors). The **As New** form takes no arguments: `Dim d As New Dog("Rex")` is a syntax error. **Static** does not accept them in an initializer either: `Static d As Dog = New Dog("Rex")` fails with TB5074. Declare the **Static** variable, then assign it with **Set**.
+: *optional* (twinBASIC) The arguments passed to the class's **Sub New** constructor, separated by commas --- `New Dog("Rex")`. The class must declare a **Sub New** whose parameters match; see [Parameterized Class Constructors](../../Features/Advanced/Classes-and-Modules#parameterized-class-constructors). The **As New** form takes no arguments: `Dim d As New Dog("Rex")` is a syntax error. So **As New** needs a class that can be created without arguments: one with a **Sub New** that takes none, or a `Class_Initialize`. For a class whose only **Sub New** takes arguments --- even if every argument is **Optional** --- **As New** fails with TB5121, *can't use this type with As-New syntax as it doesn't have a parameterless constructor*. **Static** does not accept them in an initializer either: `Static d As Dog = New Dog("Rex")` fails with TB5074. Declare the **Static** variable, then assign it with **Set**.
 
 When **New** is used in a declaration, no instance is created at the point of declaration. Instead, an instance is created automatically the first time the variable is referenced after declaration. Each time the variable is set to **Nothing** and then referenced again, a new instance is created.
 
diff --git a/docs/Reference/Core/ReDim.md b/docs/Reference/Core/ReDim.md
index 2bda0f90..4c81c015 100644
--- a/docs/Reference/Core/ReDim.md
+++ b/docs/Reference/Core/ReDim.md
@@ -29,6 +29,8 @@ The **ReDim** statement is used to size or resize a dynamic array that has alrea
 
 Use the **ReDim** statement repeatedly to change the number of elements and dimensions in an array. However, an array declared with one data type cannot later be changed to another data type by **ReDim**, unless the array is contained in a **Variant**. If the array is contained in a **Variant**, the type of the elements can be changed by using an **As** *type* clause, unless the **Preserve** keyword is used, in which case no changes of data type are permitted.
 
+**ReDim** also works on a **Variant** that holds a value other than an array, or nothing at all: the value is discarded and the **Variant** then holds the new array. **ReDim Preserve** on a **Variant** that holds a value other than an array raises error 13 (*Type mismatch*).
+
 With the **Preserve** keyword, only the last array dimension can be resized, and the number of dimensions cannot change. For example, when the array has only one dimension, that dimension can be resized because it is the last and only dimension. However, when the array has two or more dimensions, only the size of the last dimension can change while still preserving the contents of the array.
 
 The following example shows how to increase the size of the last dimension of a dynamic array without erasing any existing data contained in the array.
diff --git a/docs/Reference/Core/Topic-Preprocessor.md b/docs/Reference/Core/Topic-Preprocessor.md
index 848f5d9d..2f8943aa 100644
--- a/docs/Reference/Core/Topic-Preprocessor.md
+++ b/docs/Reference/Core/Topic-Preprocessor.md
@@ -57,6 +57,8 @@ Conditional compiler constants are always evaluated at the module level regardle
 
 twinBASIC provides a set of built-in compiler constants --- `Win64`, `Win32`, `TWINBASIC`, `TWINBASIC_BUILD`, `VBA7`, etc. See the dedicated [Compiler Constants](../../Reference/Compiler-Constants) page for the full list and what each one means.
 
+`#Const` can redefine a built-in compiler constant. As with any `#Const`, the new value applies only in the module that declares it: after `#Const Win32 = 0`, `#If Win32` is false in that module and still true everywhere else.
+
 ### Example
 
 This example uses the `Win64` predefined constant to select platform-specific imports, and a project-defined `DEBUG_BUILD` constant to enable extra logging only in debug builds.
diff --git a/docs/Reference/Default/VBA/FileSystem/FileCopy.md b/docs/Reference/Default/VBA/FileSystem/FileCopy.md
index d43de8f4..4de4bd12 100644
--- a/docs/Reference/Default/VBA/FileSystem/FileCopy.md
+++ b/docs/Reference/Default/VBA/FileSystem/FileCopy.md
@@ -21,6 +21,9 @@ Syntax: **FileCopy** *source*, *destination*
 
 An error occurs when **FileCopy** is used on a file that is currently open.
 
+> [!NOTE]
+> twinBASIC raises run-time error -2147467259 (`&H80004005`, *Unspecified error*) for a file that is open, for **Input** as well as for **Append**. VB6 raises error 55 (*File already open*) for a file open for **Append**, and copies a file open for **Input** without an error.
+
 ### Example
 
 This example uses the **FileCopy** statement to copy one file to another. For the purposes of this example, assume that the file contains some data.

From 37d731823b5290676ab58717e8ab3b06ae2098a2 Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 18:48:07 +0200
Subject: [PATCH 21/22] bugs: As New refuses an all-Optional constructor;
 FileCopy of an open file differs from VB6

---
 BUGS-TO-REPORT.md | 63 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/BUGS-TO-REPORT.md b/BUGS-TO-REPORT.md
index 4d4da183..ac0eb062 100644
--- a/BUGS-TO-REPORT.md
+++ b/BUGS-TO-REPORT.md
@@ -1338,3 +1338,66 @@ a project holding only it and a two-line `Sub Main`, with no resources: `tbbuild
 The same project with `[PopulateFrom("probe")]` builds and reports the one TB5083 row. The
 rows for `(True)`, `(False)` and `(1)` come from the sweep's batches, not from that
 project.
+
+## `As New` refuses a class whose only constructor has all-`Optional` arguments
+
+**Build:** BETA 995; BETA 983 accepts it and runs it
+**Severity:** code that compiled before BETA 993 stops compiling, and the two checks for "can
+this class be created without arguments" disagree.
+
+```
+Class COpt
+    Public V As Long
+    Public Sub New(Optional ByVal n As Long = 3)
+        V = n
+    End Sub
+End Class
+
+Module Probe
+    Public Sub T()
+        Dim x As New COpt
+        Debug.Print x.V
+    End Sub
+End Module
+```
+
+fails on the `Dim` with TB5121 `can't use this type with As-New syntax as it doesn't have a
+parameterless constructor`. The same class satisfies TB5135, the check for COM exposure: it
+compiles as a public class without `[COMCreatable(False)]`, so that check counts the
+constructor as one that takes no arguments. On BETA 983 the reproduction compiles, and `x.V`
+prints `3`. TB5121 is the diagnostic BETA 993's notes describe ("classes with
+[COMCreatable(False)] set on them cannot be used as an As-New datatype"), corrected in 995.
+
+**What does not reproduce it:** a class with a `Class_Initialize` beside a `Sub New` that takes
+a required argument, or with a second `Sub New` with no parameters, is accepted. A class whose
+only `Sub New` takes a required argument is refused, `Private` or `[COMCreatable(False)]`
+alike, which is the diagnostic working as intended.
+
+**Observed** on 2026-10-01 with compile probes through `tbbuild`, each case a project of its
+own, on BETA 995 and BETA 983; the run on 983 was a compiled EXE through `tbrun`.
+
+## `FileCopy` of an open file raises `&H80004005`, where VB6 raises 55 or copies it
+
+**Build:** BETA 995; BETA 983 copied an open file with no error
+**Severity:** code that handles VB6's error 55 does not recognise the error, and a copy that
+VB6 makes is refused.
+
+```
+Dim f As String = Environ$("TEMP") & "\probe.txt"
+Open f For Output As #1: Print #1, "one": Close #1
+On Error Resume Next
+Open f For Append As #2
+FileCopy f, f & ".copy"
+Debug.Print Err.Number, Err.Description
+```
+
+prints `-2147467259 Unspecified error`. VB6 prints `55 File already open`. With the file
+open `For Input` instead, twinBASIC raises the same `-2147467259`, and VB6 copies the file
+without an error. BETA 984's notes list the change ("FileSystem.FileCopy function would
+previously allow copying of an already open file without error"); only the error number and
+the `Input` case differ from VB6.
+
+**What does not reproduce it:** the file closed.
+
+**Observed** on 2026-10-01: the twinBASIC lines through `tbrun` on BETA 995 and BETA 983, the
+VB6 lines from the same statements compiled by `VB6.EXE /make` and run.

From bf2ce140ac0677393a47d8aca3090e856dc5d4ce Mon Sep 17 00:00:00 2001
From: Kuba Sunderland-Ober <kuba@mareimbrium.org>
Date: Thu, 1 Oct 2026 18:55:34 +0200
Subject: [PATCH 22/22] docs: LLVM-compiled code ignores Debug.Assert and skips
 its condition (BETA 995)

---
 docs/LLVM/Getting-Started.md        | 2 ++
 docs/Reference/Default/VBA/Debug.md | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/docs/LLVM/Getting-Started.md b/docs/LLVM/Getting-Started.md
index 087cadca..9406f241 100644
--- a/docs/LLVM/Getting-Started.md
+++ b/docs/LLVM/Getting-Started.md
@@ -57,6 +57,8 @@ Building with LLVM does not currently work on Windows 7; Windows 10 or 11 is rec
 
 The main feature not yet supported is passing an error up to the calling procedure. If an error occurs in a procedure that has no error handler, its caller does not receive the error; instead, the program crashes with an unhandled error. A fix is planned.
 
+Code compiled with LLVM ignores [**Debug.Assert**](../tB/Modules/Debug#assert): the statement does not stop, and its condition is not evaluated.
+
 All other language features should work, in both 32-bit and 64-bit builds. Please [report](../FAQ#bug-reporting) any crash that LLVM causes, and any message saying "a feature used in your code is not yet supported with the LLVM compiler".
 
 ## General LLVM options
diff --git a/docs/Reference/Default/VBA/Debug.md b/docs/Reference/Default/VBA/Debug.md
index 3a76f037..ec895d45 100644
--- a/docs/Reference/Default/VBA/Debug.md
+++ b/docs/Reference/Default/VBA/Debug.md
@@ -84,6 +84,8 @@ Syntax: **Debug.Assert** *booleanexpression*
 *booleanexpression*
 : An expression evaluating to **True** or **False**. Execution continues when it is **True** and breaks when it is **False**.
 
+In a procedure compiled with [LLVM](../../LLVM/Getting-Started), **Debug.Assert** is ignored: it does not break, and *booleanexpression* is not evaluated.
+
 Use it to state something the surrounding code relies on, so a violated assumption stops at the line that states it rather than further away.
 
 ```tb check_build