From 4ebdea0354da6116f3de255324db8009ef463dd3 Mon Sep 17 00:00:00 2001
From: Sridhar Ratnakumar <srid@srid.ca>
Date: Mon, 28 Sep 2026 09:53:01 -0400
Subject: [PATCH 1/2] Fix --watch crash on new fsnotify event constructors
 (#679)

fsnotify 0.4 added CloseWrite, ModifiedAttributes and
WatchedDirectoryRemoved, which mkEventPathRelative did not match,
crashing on the first file save. Use a record update on eventPath so
all constructors are handled.
---
 src/Neuron/Reactor.hs | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/src/Neuron/Reactor.hs b/src/Neuron/Reactor.hs
index 03880086..1819db66 100644
--- a/src/Neuron/Reactor.hs
+++ b/src/Neuron/Reactor.hs
@@ -216,15 +216,10 @@ watchDirWithDebounce ms dirPath' = do
     nubByKeepLast f =
       reverse . nubBy f . reverse
     mkEventPathRelative :: FilePath -> FSN.Event -> Maybe FSN.Event
-    mkEventPathRelative baseDir = \case
-      FSN.Added fp t d ->
-        mkR fp <&> \p -> FSN.Added p t d
-      FSN.Modified fp t d ->
-        mkR fp <&> \p -> FSN.Modified p t d
-      FSN.Removed fp t d ->
-        mkR fp <&> \p -> FSN.Removed p t d
-      FSN.Unknown fp t d e ->
-        mkR fp <&> \p -> FSN.Unknown p t d e
+    mkEventPathRelative baseDir fse =
+      -- Use record update (rather than matching on each constructor), so that
+      -- new constructors in fsnotify (eg: CloseWrite) are handled. See #679.
+      mkR (FSN.eventPath fse) <&> \p -> fse {FSN.eventPath = p}
       where
         mkR fp = do
           let rel = makeRelative baseDir fp

From 6715c98d892686ef94c34ab7659509c2812b28f3 Mon Sep 17 00:00:00 2001
From: Sridhar Ratnakumar <srid@srid.ca>
Date: Mon, 28 Sep 2026 13:27:19 -0400
Subject: [PATCH 2/2] Add changelog entry and bump to 1.9.38.0

---
 CHANGELOG.md | 1 +
 neuron.cabal | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index e40d178b..5df12928 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 - Add Apple Silicon (aarch64-darwin) support (#677)
 - Upgrade to GHC 9.10 (#677)
+- Fix `gen --watch` crashing with "Non-exhaustive patterns" on file save (#679)
 - Web interface
   - Introducing *impulse* -- foundation for upcoming advanced search, replacing both z-index and legacy JS search (#108)
   - Remove autoscroll behaviour (which had questionable value to begin with)
diff --git a/neuron.cabal b/neuron.cabal
index a799c159..5e7dddcd 100644
--- a/neuron.cabal
+++ b/neuron.cabal
@@ -1,6 +1,6 @@
 cabal-version: 2.4
 name: neuron
-version: 1.9.37.0
+version: 1.9.38.0
 license: AGPL-3.0-only
 copyright: 2020 Sridhar Ratnakumar
 maintainer: srid@srid.ca