feat: add es2026 as a valid target and lib by a-tarasyuk · Pull Request #64096 · microsoft/TypeScript

Oleksandr Tarasiuk (a-tarasyuk) · 2026-08-30T10:30:41Z

Fixes #63704

Copilot

Pull request overview

Adds ES2026 compiler-target and standard-library support, including the APIs requested by #63704.

Changes:

Registers es2026 as a target, default standard target, and library.
Adds ES2026 API declarations and preserves esnext.* aliases.
Adds conformance tests and refreshes generated baselines.

Reviewed changes

Copilot reviewed 136 out of 540 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
`packages/typescript/src/enums/scriptTarget*.ts`	Exposes `ES2026` publicly.
`packages/typescript/test/{async,sync}/api.test.ts`	Updates target diagnostics.
`tsc/internal/core/{compileroptions,scripttarget_stringer_generated}.go`	Defines and formats the target.
`tsc/internal/tsoptions/enummaps.go`	Registers target, libraries, and compatibility aliases.
`tsc/internal/transformers/estransforms/definitions.go`	Selects the ES2026 transform pipeline.
`tsc/internal/checker/utilities.go`	Adds ES2026 library suggestions.
`tsc/internal/bundled/libs/lib.es2026*.d.ts`	Defines the ES2026 library and APIs.
`tsc/internal/bundled/libs/lib.esnext.d.ts`	Makes ESNext inherit ES2026.
`tsc/internal/bundled/{embed_generated,libs_generated}.go`	Embeds and registers new libraries.
`tsc/internal/compiler/program_test.go`	Updates expected ESNext library ordering.
`tsc/testdata/fixtures/compiler/*.ts`	Synchronizes compiler fixtures.
`tsc/testdata/tests/cases/conformance/es2026/*.ts`	Tests ES2026 APIs and diagnostics.
`tsc/testdata/baselines/reference/**`	Refreshes generated compiler, build, watch, API, and conformance baselines.

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…eat/63704

Copilot

🔵 Needs a closer look

The public target and library surface spans hundreds of generated baselines and warrants final human validation against the ES2026 specification.

Review details

Files reviewed: 136/540 changed files
Comments generated: 0 new
Review effort level: Balanced

Jake Bailey (jakebailey) · 2026-09-04T18:01:07Z

+     * Indicates whether the provided value is an object returned by `JSON.rawJSON()`.
+     * @param value The value to test.
+     */
+    isRawJSON(value: unknown): value is RawJSON;


A bit funky that this is just an interface but I think that's just how it is?

https://tc39.es/ecma262/2026/multipage/structured-data.html#sec-json.israwjson
https://tc39.es/ecma262/2026/multipage/structured-data.html#sec-json.rawjson

Maybe I’m missing something, but it seems like JSON.rawJSON() returns a regular object, and there’s no RawJSON constructor or global.

Yeah, it's just one of those "it has an internal slot" things nobody can observe... Like who's to say I can't assign basically anything to RawJSON if it has rawJSON: string. But we can't do anything about it

Yeah, I did wonder if it should be a class with a private field though. You can't forge this type.

I’ve added a private field through a class.

declare class RawJSONBase { private constructor(); private RawJSON_typekey: RawJSONBase; } interface RawJSON extends RawJSONBase { readonly rawJSON: string; }

Interesting, I had no idea this existed; the scripthost types are pretty legacy. Probably we should have deleted them....

I'm not sure what's right here, one I think needs a class to get nominality like this, but, we typically do not do this as it makes it impossible to extend lib later.

I've switched back to using the interface. Both approaches have pros and cons, but I think the interface is a better fit here.

one I think needs a class to get nominality like this, but, we typically do not do this as it makes it impossible to extend lib later.

We do this with Iterator in lib.es2025.iterator.d.ts.

// NOTE: This is specified as what is essentially an unreachable module. All actual global declarations can be found // in the `declare global` section, below. This is necessary as there is currently no way to declare an `abstract` // member without declaring a `class`, but declaring `class Iterator<T>` globally would conflict with TypeScript's // general purpose `Iterator<T>` interface. export {}; // Abstract type that allows us to mark `next` as `abstract` declare abstract class Iterator<T, TResult = undefined, TNext = unknown> { // eslint-disable-line @typescript-eslint/no-unsafe-declaration-merging abstract next(value?: TNext): IteratorResult<T, TResult>; } // ... declare global { // Global `IteratorConstructor` interface that can be augmented by polyfills interface IteratorConstructor extends IteratorObjectConstructor { /** * Creates a native iterator from an iterator or iterable object. * Returns its input if the input already inherits from the built-in Iterator class. * @param value An iterator or iterable object to convert a native iterator. */ from<T>(value: Iterator<T, unknown, undefined> | Iterable<T, unknown, undefined>): IteratorObject<T, undefined, unknown>; } var Iterator: IteratorConstructor; }

Yeah, I would slightly prefer to do the same here since we have precedent.

export {} declare class RawJSONInstance { #isRawJson: unknown; readonly rawJSON: string; } declare global { /** * A frozen object containing JSON text for a primitive value, created by `JSON.rawJSON()`. */ interface RawJSON extends RawJSONInstance { } interface JSON { /** * Creates a frozen object containing JSON text for a primitive value. * @param text Valid JSON text representing a string, number, boolean, or null value. * @throws {SyntaxError} If `text` is not valid JSON text for a primitive value. */ rawJSON(text: string): RawJSON; /** * Indicates whether the provided value is an object returned by `JSON.rawJSON()`. * @param value The value to test. */ isRawJSON(value: unknown): value is RawJSON; } } let x: RawJSON = JSON.rawJSON("true");

Daniel Rosenwasser (@DanielRosenwasser) I've updated RawJSON

…into feat/63704

…eat/63704

Copilot

🟡 Changes recommended

The jsonRawJSON2 source and checked-in baselines disagree, causing baseline tests to fail.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Review details

Files reviewed: 146/553 changed files
Comments generated: 1
Review effort level: Balanced

…eat/63704

…into feat/63704

…eat/63704

Daniel Rosenwasser (DanielRosenwasser) · 2026-09-24T21:46:03Z

+     * Indicates whether the provided value is an object returned by `JSON.rawJSON()`.
+     * @param value The value to test.
+     */
+    isRawJSON(value: unknown): value is RawJSON;


Yeah, I would slightly prefer to do the same here since we have precedent.

export {} declare class RawJSONInstance { #isRawJson: unknown; readonly rawJSON: string; } declare global { /** * A frozen object containing JSON text for a primitive value, created by `JSON.rawJSON()`. */ interface RawJSON extends RawJSONInstance { } interface JSON { /** * Creates a frozen object containing JSON text for a primitive value. * @param text Valid JSON text representing a string, number, boolean, or null value. * @throws {SyntaxError} If `text` is not valid JSON text for a primitive value. */ rawJSON(text: string): RawJSON; /** * Indicates whether the provided value is an object returned by `JSON.rawJSON()`. * @param value The value to test. */ isRawJSON(value: unknown): value is RawJSON; } } let x: RawJSON = JSON.rawJSON("true");

Daniel Rosenwasser (DanielRosenwasser) · 2026-09-24T21:50:02Z

TypeScript Bot (@typescript-bot) test it

typescript-automation · 2026-09-24T21:50:08Z

Starting jobs; this comment will be updated as builds start and complete.

Command	Status	Results
`test top400`	✅ Started	✅ Results
`user test this`	✅ Started	👀 Results
`run dt`	✅ Started	✅ Results
`perf test this faster`	✅ Started	👀 Results

typescript-automation · 2026-09-24T22:17:32Z

Daniel Rosenwasser (@DanielRosenwasser)
The results of the perf run you requested are in!

Here they are:

tsc

Comparison Report - baseline..pr

_Metric	_baseline	_pr	_Delta	_Best	_Worst	_p-value
_{Compiler-Unions - native}
_Errors	₄₁	₄₁	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_115,480	_115,480	_~	_~	_~	_{p=1.000 n=12}
_Types	_96,949	_96,949	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{148,823k (± 0.43%)}	_{148,707k (± 0.49%)}	_~	_147,302k	_150,876k	_{p=0.755 n=12}
_{Memory Allocs}	_{2,271,701 (± 0.00%)}	_{2,271,716 (± 0.01%)}	_~	_2,271,445	_2,272,019	_{p=0.920 n=12}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.040s (± 3.21%)}	_{0.041s (± 4.51%)}	_~	_0.036s	_0.045s	_{p=0.424 n=12}
_{Bind Time}	_{0.013s (±10.32%)}	_{0.013s (±13.51%)}	_~	_0.010s	_0.018s	_{p=0.877 n=12}
_{Check Time}	_{0.502s (± 0.61%)}	_{0.505s (± 0.76%)}	_~	_0.497s	_0.515s	_{p=0.296 n=12}
_{Emit Time}	_{0.267s (± 1.68%)}	_{0.272s (± 1.71%)}	_~	_0.262s	_0.285s	_{p=0.173 n=12}
_{Total Time}	_{0.828s (± 0.65%)}	_{0.837s (± 0.76%)}	_{+0.009s (+ 1.07%)}	_0.822s	_0.854s	_{p=0.019 n=12}
_{angular-1 - native}
_Errors	₃	₃	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_{846,550 (± 0.08%)}	_{847,446 (± 0.05%)}	_{+896 (+ 0.11%)}	_846,024	_848,445	_{p=0.033 n=12}
_Types	_{250,004 (± 0.00%)}	_{250,003 (± 0.00%)}	_~	_250,001	_250,007	_{p=0.809 n=12}
_{Memory Used}	_{793,393k (± 0.05%)}	_{793,642k (± 0.09%)}	_~	_792,420k	_796,549k	_{p=0.755 n=12}
_{Memory Allocs}	_{12,959,123 (± 0.03%)}	_{12,960,454 (± 0.04%)}	_~	_12,954,022	_12,972,672	_{p=0.755 n=12}
_{Config Time}	_0.016s	_0.016s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.274s (± 2.05%)}	_{0.276s (± 3.43%)}	_~	_0.242s	_0.289s	_{p=0.164 n=12}
_{Bind Time}	_{0.063s (± 9.48%)}	_{0.064s (±13.66%)}	_~	_0.057s	_0.103s	_{p=0.775 n=12}
_{Check Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=12}
_{Emit Time}	_{1.628s (± 1.31%)}	_{1.621s (± 1.41%)}	_~	_1.576s	_1.709s	_{p=0.432 n=12}
_{Total Time}	_{1.997s (± 1.40%)}	_{1.992s (± 1.24%)}	_~	_1.947s	_2.091s	_{p=0.943 n=12}
_{mui-docs - native}
_Errors	_{11,401 (± 0.05%)}	_{11,402 (± 0.03%)}	_~	_11,390	_11,407	_{p=0.579 n=12}
_Symbols	_4,402,219	_4,402,219	_~	_~	_~	_{p=1.000 n=12}
_Types	_1,489,173	_1,489,173	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{4,787,597k (± 0.03%)}	_{4,786,855k (± 0.04%)}	_~	_4,781,840k	_4,790,844k	_{p=0.514 n=12}
_{Memory Allocs}	_{42,335,178 (± 0.05%)}	_{42,321,239 (± 0.03%)}	_~	_42,292,350	_42,374,132	_{p=0.266 n=12}
_{Config Time}	_{0.015s (± 2.10%)}	_{0.015s (± 2.02%)}	_~	_0.015s	_0.016s	_{p=1.000 n=12}
_{Parse Time}	_{0.555s (± 2.61%)}	_{0.555s (± 2.94%)}	_~	_0.497s	_0.585s	_{p=0.854 n=12}
_{Bind Time}	_0.002s	_0.002s	_~	_~	_~	_{p=1.000 n=12}
_{Check Time}	_{15.408s (± 0.31%)}	_{15.261s (± 0.52%)}	_{-0.147s (- 0.95%)}	_15.115s	_15.503s	_{p=0.006 n=12}
_{Emit Time}	_{0.438s (± 2.14%)}	_{0.446s (± 2.78%)}	_~	_0.427s	_0.470s	_{p=0.615 n=12}
_{Total Time}	_{17.188s (± 0.32%)}	_{17.033s (± 0.48%)}	_{-0.155s (- 0.90%)}	_16.881s	_17.248s	_{p=0.004 n=12}
_{strada-build-src - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,394,252	_1,394,252	_~	_~	_~	_{p=1.000 n=12}
_Types	_443,566	_443,566	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{1,660,639k (± 0.36%)}	_{1,665,643k (± 0.40%)}	_~	_1,654,488k	_1,685,656k	_{p=0.219 n=12}
_{Memory Allocs}	_{83,659,486 (± 0.02%)}	_{83,610,986 (± 0.11%)}	_~	_83,183,665	_83,718,525	_{p=0.514 n=12}
_{Config Time}	_{0.004s (±24.18%)}	_{0.004s (±13.41%)}	_~	_0.003s	_0.005s	_{p=0.656 n=12}
_{Parse Time}	_{0.266s (± 2.76%)}	_{0.269s (± 1.49%)}	_~	_0.261s	_0.282s	_{p=0.522 n=12}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Check Time}	_{1.827s (± 0.40%)}	_{1.847s (± 0.59%)}	_{+0.021s (+ 1.14%)}	_1.816s	_1.881s	_{p=0.004 n=12}
_{Emit Time}	_{0.294s (± 3.41%)}	_{0.278s (± 2.21%)}	_{🟩-0.017s (- 5.61%)}	_0.264s	_0.301s	_{p=0.005 n=12}
_{Total Time}	_{21.146s (± 0.62%)}	_{21.182s (± 0.79%)}	_~	_20.907s	_21.811s	_{p=0.799 n=12}
_{strada-compiler - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_337,531	_337,531	_~	_~	_~	_{p=1.000 n=12}
_Types	_198,885	_198,885	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{319,627k (± 0.02%)}	_{319,651k (± 0.04%)}	_~	_319,330k	_319,967k	_{p=0.887 n=12}
_{Memory Allocs}	_{4,673,099 (± 0.01%)}	_{4,673,050 (± 0.01%)}	_~	_4,671,792	_4,674,156	_{p=0.932 n=12}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.113s (± 4.01%)}	_{0.116s (± 3.15%)}	_~	_0.107s	_0.126s	_{p=0.353 n=12}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Check Time}	_{1.069s (± 0.40%)}	_{1.081s (± 0.38%)}	_{+0.011s (+ 1.08%)}	_1.072s	_1.097s	_{p=0.000 n=12}
_{Emit Time}	_{0.129s (±11.16%)}	_{0.130s (±13.11%)}	_~	_0.094s	_0.159s	_{p=0.723 n=12}
_{Total Time}	_{1.364s (± 0.85%)}	_{1.380s (± 0.79%)}	_~	_1.353s	_1.409s	_{p=0.057 n=12}
_{ts-pre-modules - native}
_Errors	₈₇	₈₇	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_305,179	_305,179	_~	_~	_~	_{p=1.000 n=12}
_Types	_181,926	_181,926	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{277,185k (± 0.02%)}	_{277,175k (± 0.03%)}	_~	_276,888k	_277,304k	_{p=0.944 n=12}
_{Memory Allocs}	_{1,642,232 (± 0.02%)}	_{1,642,135 (± 0.02%)}	_~	_1,641,443	_1,642,530	_{p=0.671 n=12}
_{Config Time}	_{0.000s (±217.90%)}	_{0.000s (±113.79%)}	_~	_0.000s	_0.001s	_{p=0.590 n=12}
_{Parse Time}	_{0.094s (± 4.42%)}	_{0.099s (± 4.31%)}	_~	_0.087s	_0.111s	_{p=0.122 n=12}
_{Bind Time}	_{0.039s (±11.11%)}	_{0.034s (± 5.49%)}	_~	_0.028s	_0.037s	_{p=0.351 n=12}
_{Check Time}	_{0.844s (± 0.57%)}	_{0.851s (± 0.68%)}	_~	_0.839s	_0.863s	_{p=0.075 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{0.990s (± 1.08%)}	_{0.998s (± 0.64%)}	_~	_0.985s	_1.013s	_{p=0.155 n=12}
_{vscode - native}
_Errors	₃₇₁	₃₇₁	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_9,665,223	_9,665,223	_~	_~	_~	_{p=1.000 n=12}
_Types	_3,259,959	_3,259,959	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{6,377,792k (± 0.01%)}	_{6,378,611k (± 0.01%)}	_~	_6,376,321k	_6,380,555k	_{p=0.198 n=12}
_{Memory Allocs}	_{48,914,782 (± 0.02%)}	_{48,911,032 (± 0.01%)}	_~	_48,898,660	_48,934,582	_{p=0.887 n=12}
_{Config Time}	_{0.066s (± 0.47%)}	_{0.066s (± 0.49%)}	_~	_0.065s	_0.066s	_{p=1.000 n=12}
_{Parse Time}	_{1.818s (± 2.84%)}	_{1.816s (± 3.24%)}	_~	_1.681s	_1.931s	_{p=0.932 n=12}
_{Bind Time}	_{0.466s (±15.86%)}	_{0.495s (±17.65%)}	_~	_0.399s	_0.741s	_{p=0.831 n=12}
_{Check Time}	_{12.606s (± 0.99%)}	_{12.530s (± 1.14%)}	_~	_12.146s	_12.737s	_{p=0.340 n=12}
_{Emit Time}	_{4.007s (±10.96%)}	_{4.191s (±12.14%)}	_~	_3.662s	_5.622s	_{p=0.767 n=12}
_{Total Time}	_{19.071s (± 1.86%)}	_{19.207s (± 2.15%)}	_~	_18.710s	_20.367s	_{p=0.681 n=12}
_{webpack - native}
_Errors	₈₄₈	₈₄₈	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,358,721	_1,358,721	_~	_~	_~	_{p=1.000 n=12}
_Types	_597,693	_597,693	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{954,136k (± 0.02%)}	_{954,307k (± 0.01%)}	_~	_954,039k	_954,534k	_{p=0.062 n=12}
_{Memory Allocs}	_{6,222,452 (± 0.01%)}	_{6,225,184 (± 0.03%)}	_{+2,732 (+ 0.04%)}	_6,222,272	_6,231,164	_{p=0.000 n=12}
_{Config Time}	_0.009s	_0.009s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.263s (± 2.23%)}	_{0.262s (± 1.59%)}	_~	_0.242s	_0.268s	_{p=0.743 n=12}
_{Bind Time}	_{0.064s (±17.71%)}	_{0.059s (±13.99%)}	_~	_0.052s	_0.100s	_{p=0.896 n=12}
_{Check Time}	_{2.237s (± 0.59%)}	_{2.242s (± 0.78%)}	_~	_2.174s	_2.277s	_{p=0.989 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{2.606s (± 0.25%)}	_{2.606s (± 0.53%)}	_~	_2.565s	_2.642s	_{p=0.579 n=12}
_{xstate-main - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,045,695	_1,037,734	_{-7,961 (- 0.76%)}	_~	_~	_{p=0.000 n=12}
_Types	_383,049	_378,534	_{-4,515 (- 1.18%)}	_~	_~	_{p=0.000 n=12}
_{Memory Used}	_{611,306k (± 0.01%)}	_{607,653k (± 0.01%)}	_{-3,653k (- 0.60%)}	_607,454k	_607,838k	_{p=0.000 n=12}
_{Memory Allocs}	_{4,829,520 (± 0.03%)}	_{4,801,246 (± 0.05%)}	_{-28,275 (- 0.59%)}	_4,797,064	_4,811,695	_{p=0.000 n=12}
_{Config Time}	_{0.003s (±10.34%)}	_{0.003s (±13.14%)}	_~	_0.002s	_0.003s	_{p=0.400 n=12}
_{Parse Time}	_{0.145s (± 4.32%)}	_{0.147s (± 2.83%)}	_~	_0.138s	_0.162s	_{p=0.619 n=12}
_{Bind Time}	_{0.050s (±19.21%)}	_{0.038s (±13.18%)}	_{🟩-0.011s (-22.65%)}	_0.033s	_0.053s	_{p=0.008 n=12}
_{Check Time}	_{1.201s (± 0.86%)}	_{1.093s (± 0.86%)}	_{🟩-0.107s (- 8.93%)}	_1.078s	_1.136s	_{p=0.000 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{1.407s (± 0.65%)}	_{1.292s (± 0.87%)}	_{🟩-0.115s (- 8.17%)}	_1.267s	_1.333s	_{p=0.000 n=12}

System info unknown

Hosts

native

Scenarios

Compiler-Unions - native
angular-1 - native
mui-docs - native
strada-build-src - native
strada-compiler - native
ts-pre-modules - native
vscode - native
webpack - native
xstate-main - native

_Benchmark	_Name	_Iterations
_Current	_pr	₁₂
_Baseline	_baseline	₁₂

Developer Information:

Download Benchmarks

typescript-automation · 2026-09-24T22:22:24Z

Daniel Rosenwasser (@DanielRosenwasser) Here are the results of running the user tests with tsc comparing main and refs/pull/64096/merge:

There were infrastructure failures potentially unrelated to your change:

1 instance of "Git clone failed"
1 instance of "Package install failed"

Otherwise...

Something interesting changed - please have a look.

Details

lodash

/mnt/vss/work/1/s/ts_downloads//m/lodash/tsconfig.json

[MISSING] error TS2345: Argument of type '{ castArray: () => any[]; clone: (value: any) => any; cloneDeep: (value: any) => any; cloneDeepWith: (value: any, customizer?: Function | undefined) => any; cloneWith: (value: any, customizer?: Function | undefined) => any; ... 50 more ...; toString: (value: any) => string; }' is not assignable to parameter of type 'string'.
- /mnt/vss/work/1/s/ts_downloads//m/lodash/node_modules/lodash/fp/lang.js(2,26)

typescript-automation · 2026-09-24T23:01:00Z

Daniel Rosenwasser (@DanielRosenwasser) Here are the results of running the top 400 repos with tsc comparing main and refs/pull/64096/merge:

Everything looks good!

typescript-automation · 2026-09-25T05:28:55Z

Hey Daniel Rosenwasser (@DanielRosenwasser), the results of running the DT tests are ready.

Everything looks the same!

You can check the log here.

…eat/63704

Copilot

Copilot review overview

🟢 Approval recommended

The target, libraries, API surface, and conformance coverage are coherent; only a non-blocking JSDoc typo remains.

Review effort: Balanced
Findings: None

Copilot

Copilot review overview

🟢 Approval recommended

The target registration, library declarations, API exposure, and corresponding baselines are consistent and adequately tested.

Review effort: Balanced
Findings: None

Copilot

Copilot review overview

🟢 Approval recommended

Target registration, library declarations, compatibility mappings, and conformance coverage are consistent.

Review effort: Balanced
Findings: None

Jake Bailey (jakebailey)

I don't think we typically add a slew of tests for lib files but, it's fine

typescript-automation Bot added the For Milestone Bug PRs that fix a bug with a specific milestone label Aug 30, 2026

typescript-automation Bot assigned Daniel Rosenwasser (DanielRosenwasser) Aug 30, 2026

feat: add es2026 as a valid target and lib

a022dd9

Oleksandr Tarasiuk (a-tarasyuk) force-pushed the feat/63704 branch from fefecb3 to a022dd9 Compare August 31, 2026 21:08

Oleksandr Tarasiuk (a-tarasyuk) marked this pull request as ready for review August 31, 2026 21:27

Copilot AI balanced review requested due to automatic review settings August 31, 2026 21:27

Copilot started reviewing on behalf of Oleksandr Tarasiuk (a-tarasyuk) August 31, 2026 21:28 View session

Copilot AI reviewed Aug 31, 2026

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Oleksandr Tarasiuk (a-tarasyuk) added 3 commits September 1, 2026 08:55

Merge branch 'main' into feat/63704

6d0205a

Merge branch 'main' of https://github.com/microsoft/TypeScript into f…

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…eat/63704

Merge branch 'main' into feat/63704

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Jake Bailey (jakebailey) requested a balanced review from Copilot September 4, 2026 17:54

Jake Bailey (jakebailey) reviewed Sep 4, 2026

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Comment thread tsc/internal/bundled/libs/lib.es2026.error.d.ts Outdated

Copilot started reviewing on behalf of Jake Bailey (jakebailey) September 4, 2026 17:57 View session

Copilot AI reviewed Sep 4, 2026

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restore spec wording for Error.isError

43135e9

Jake Bailey (jakebailey) requested changes Sep 4, 2026

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Oleksandr Tarasiuk (a-tarasyuk) added 4 commits September 4, 2026 21:45

clean up es2026 lib

2099baf

Merge branch 'feat/63704' of https://github.com/a-tarasyuk/TypeScript …

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…into feat/63704

update baseline

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Merge branch 'main' of https://github.com/microsoft/TypeScript into f…

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…eat/63704

Oleksandr Tarasiuk (a-tarasyuk) requested a review from Jake Bailey (jakebailey) September 4, 2026 19:25

Oleksandr Tarasiuk (a-tarasyuk) added 2 commits September 8, 2026 09:42

add a private field to RawJSON

3d4c1c1

Merge branch 'main' of https://github.com/microsoft/TypeScript into f…

acabd00

…eat/63704

Oleksandr Tarasiuk (a-tarasyuk) requested a balanced review from Copilot September 8, 2026 06:46

Copilot started reviewing on behalf of Oleksandr Tarasiuk (a-tarasyuk) September 8, 2026 06:46 View session

Copilot AI reviewed Sep 8, 2026

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Comment thread tsc/testdata/tests/cases/conformance/es2026/jsonRawJSON2.ts

update baseline

5af4a72

Oleksandr Tarasiuk (a-tarasyuk) requested a balanced review from Copilot September 8, 2026 06:56

Copilot started reviewing on behalf of Oleksandr Tarasiuk (a-tarasyuk) September 8, 2026 06:56 View session

Oleksandr Tarasiuk (a-tarasyuk) added 8 commits September 9, 2026 19:16

use a plain interface for RawJSON

c6f0b6e

Merge branch 'main' of https://github.com/microsoft/TypeScript into f…

565aad9

…eat/63704

Merge branch 'main' into feat/63704

b33d820

Merge branch 'main' into feat/63704

6cbe9ab

Merge branch 'feat/63704' of https://github.com/a-tarasyuk/TypeScript …

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…into feat/63704

Merge branch 'main' of https://github.com/microsoft/TypeScript into f…

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…eat/63704

Merge branch 'main' into feat/63704

8325bd9

Merge branch 'main' into feat/63704

a3f0a23

Daniel Rosenwasser (DanielRosenwasser) requested changes Sep 24, 2026

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Oleksandr Tarasiuk (a-tarasyuk) added 2 commits September 25, 2026 10:34

use a module-local class for RawJSON

074a75f

Merge branch 'main' of https://github.com/microsoft/TypeScript into f…

3d5e091

…eat/63704

Oleksandr Tarasiuk (a-tarasyuk) requested review from Daniel Rosenwasser (DanielRosenwasser) and a balanced review from Copilot September 25, 2026 07:35

Copilot started reviewing on behalf of Oleksandr Tarasiuk (a-tarasyuk) September 25, 2026 07:37 View session

Copilot AI reviewed Sep 25, 2026

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fix typos

b31c0e2

Oleksandr Tarasiuk (a-tarasyuk) requested a balanced review from Copilot September 25, 2026 08:06

Copilot started reviewing on behalf of Oleksandr Tarasiuk (a-tarasyuk) September 25, 2026 08:07 View session

Copilot AI reviewed Sep 25, 2026

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Daniel Rosenwasser (DanielRosenwasser) approved these changes Sep 25, 2026

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Daniel Rosenwasser (DanielRosenwasser) requested a balanced review from Copilot September 25, 2026 20:27

Copilot started reviewing on behalf of Daniel Rosenwasser (DanielRosenwasser) September 25, 2026 20:28 View session

Copilot AI reviewed Sep 25, 2026

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Jake Bailey (jakebailey) approved these changes Sep 25, 2026

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Conversation

Oleksandr Tarasiuk (a-tarasyuk) commented Aug 30, 2026

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Pull request overview

Reviewed changes

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🔵 Needs a closer look

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Oleksandr Tarasiuk (a-tarasyuk) Sep 4, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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🟡 Changes recommended

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Daniel Rosenwasser (DanielRosenwasser) commented Sep 24, 2026

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typescript-automation Bot commented Sep 24, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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typescript-automation Bot commented Sep 24, 2026

tsc

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typescript-automation Bot commented Sep 24, 2026

/mnt/vss/work/1/s/ts_downloads//m/lodash/tsconfig.json

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typescript-automation Bot commented Sep 25, 2026

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Copilot review overview

🟢 Approval recommended

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Copilot review overview

🟢 Approval recommended

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Copilot review overview

🟢 Approval recommended

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Oleksandr Tarasiuk (a-tarasyuk) Sep 4, 2026 •

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typescript-automation Bot commented Sep 24, 2026 •

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