fix: report a file removed after startTime to a watcher attached later by alexander-akait · Pull Request #345 · webpack/watchpack

alexander-akait · 2026-10-12T22:42:25Z

Summary

A watcher attached with a startTime is told about files changed since then ("watch (outdated on attach)"), but not about files removed since then. webpack pauses its watcher during a build and attaches a new one with the build's start time afterwards, so a dependency deleted while a build runs never triggers a rebuild. This made restored-commonjs-reexport flaky on macOS in webpack/webpack#22640, where FSEvents can deliver deletions after another change has started a build.

DirectoryWatcher now records when a known file is removed, forgets it when the file reappears, and reports initial-missing on attach when the removal came after startTime. Paths watched as missing still ignore it, as before.

remove a.js after startTime, then attach a watcher with that startTime
before: no event
after:  aggregated: removals = [a.js]

What kind of change does this PR introduce?

fix

Did you add tests for your changes?

Yes, in test/Watchpack.test.js: "should detect a past removal of a file (watched)" (times out without the fix) and "should not detect a removal before the start time (watched)". Both share one options object so they share one watcher pool, as webpack does.

Does this PR introduce a breaking change?

No.

If relevant, what needs to be documented once your changes are merged or what have you already documented?

n/a

Use of AI

Claude Code traced the lost removal from webpack into DirectoryWatcher.watch, wrote the fix and the tests, and ran the suite and lint. A maintainer asked for the fix to land here rather than as a webpack workaround.

🤖 Generated with Claude Code

https://claude.ai/code/session_016ZdAw4de2GgWu4X7BMY8ys

Generated by Claude Code

Summary by CodeRabbit

Bug Fixes
- Watchers attached after a file has been removed now report that removal when it occurred at or after their start time, including when the watcher is shared across instances.
- Removals that occurred before a watcher’s start time are not reported as aggregated removal events. This preserves the distinction between changes relevant to a watcher’s timeframe and earlier removals.

changeset-bot · 2026-10-12T22:42:29Z

🦋 Changeset detected

Latest commit: cc817ae

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
watchpack	Patch

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coderabbitai · 2026-10-12T22:47:42Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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📒 Files selected for processing (2)

lib/DirectoryWatcher.js
test/Watchpack.test.js

🚧 Files skipped from review as they are similar to previous changes (2)

test/Watchpack.test.js
lib/DirectoryWatcher.js

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Walkthrough

DirectoryWatcher now records timestamps for non-initial file removals and clears them when a path is observed again. When a watcher attaches and its target is missing, the check also compares the watcher’s start time with the recorded removal time. Added tests cover start times before and at the removal time.

Priority: ➖ Normal

Merge Risk: ⚪ Minimal · up to cc817

The reviewed removal-reporting behavior is consistent with the intended start-time handling and is ready to merge after normal checks.

Pre-merge checks · 5

Passed checks (5 passed)

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: reporting file removals after startTime to watchers attached later.
Docstring Coverage		No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 3…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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test/Watchpack.test.js

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ESLint: 9.39.5

Error: Error while loading rule 'jest/no-deprecated-functions': Unable to detect Jest version - please ensure jest package is installed, or otherwise set version explicitly
Occurred while linting /test/Watchpack.test.js
at detectJestVersion (/.eslint-tmp/node_modules/eslint-plugin-jest/lib/rules/utils/detectJestVersion.js:22:9)
at create (/.eslint-tmp/node_modules/eslint-plugin-jest/lib/rules/no-deprecated-functions.js:31:107)
at Object.create (/.eslint-tmp/node_modules/@typescript-eslint/utils/dist/eslint-utils/RuleCreator.js:39:20)
at createRuleListeners (/.eslint-tmp/node_modules/eslint/lib/linter/linter.js:1019:15)
at /.eslint-tmp/node_modules/eslint/lib/linter/linter.js:1151:7
at Array.forEach ()
at runRules (/.eslint-tmp/node_modules/eslint/lib/linter/linter.js:1085:31)
at #flatVerifyWithoutProcessors (/.eslint-tmp/node_modules/eslint/lib/linter/linter.js:2115:4)
at Linter._verifyWithFlatConfigArrayAndWithoutProcessors (/.eslint-tmp/node_modules/eslint/lib/linter/linter.js:2203:43)
at Linter._verifyWithFlatConfigArray (/.eslint-tmp/node_modules/eslint/lib/linter/linter.js:2306:15)

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Actionable comments posted: 2

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Configuration used: Organization UI
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📒 Files selected for processing (4)

.changeset/report-removal-after-start-time.md
lib/DirectoryWatcher.js
test/Watchpack.test.js
types/DirectoryWatcher.d.ts

Included review availability: This review used your included allowance. Your plan provides up to 2 included reviews per hour; 1 remain after this review.

Regression test for the watchpack fix (webpack/watchpack#345); it passes once watchpack is bumped to the release carrying it.

codspeed · 2026-10-12T22:52:07Z

Merging this PR will not alter performance

⚠️

4 benchmarks spent significant time in system calls

System calls cannot be consistently instrumented, so they are not included in the measure, which understates the real cost. Please switch to the Walltime instrument to accurately measure system calls.

Measurement and system calls

link-resolver: cold shallow batch (depth=1, n=100)

ignored-cross-platform: regex against windows paths

link-resolver: cold medium batch (depth=5, n=100)

link-resolver: cold deep batch (depth=15, n=50)

✅ 36 untouched benchmarks

_{Comparing fix/report-removal-after-start-time (cc817ae) with main (38505ef)}

codecov · 2026-10-12T22:57:17Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.37%. Comparing base (38505ef) to head (cc817ae).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #345      +/-   ##
==========================================
+ Coverage   92.19%   92.37%   +0.18%     
==========================================
  Files           8        8              
  Lines        1307     1312       +5     
  Branches      385      388       +3     
==========================================
+ Hits         1205     1212       +7     
+ Misses         96       94       -2     
  Partials        6        6

Flag	Coverage Δ
integration	`92.37% <100.00%> (+0.18%)`	⬆️

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…al in tests

Regression test for the watchpack fix (webpack/watchpack#345); it passes once watchpack is bumped to the release carrying it.

…22650) * docs(agents): fix a dependency's bug in the dependency, not with a workaround * fix(watch): rebuild when a file is removed while a build is running Regression test for the watchpack fix (webpack/watchpack#345); it passes once watchpack is bumped to the release carrying it.

fix: report a file removed after startTime to a watcher attached later

93acee1

coderabbitai Bot reviewed Oct 12, 2026

View reviewed changes

Comment thread lib/DirectoryWatcher.js Outdated

Comment thread test/Watchpack.test.js Outdated

alexander-akait mentioned this pull request Oct 12, 2026

fix(watch): rebuild when a file is removed while a build is running webpack/webpack#22650

Merged

fix: key removal times like watchers, and wait for the observed remov…

cc817ae

…al in tests

alexander-akait merged commit d2143ec into main Oct 13, 2026
51 checks passed

alexander-akait deleted the fix/report-removal-after-start-time branch October 13, 2026 09:44

github-actions Bot mentioned this pull request Oct 13, 2026

chore(release): new release #337

Merged

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fix: report a file removed after startTime to a watcher attached later - #345

fix: report a file removed after startTime to a watcher attached later#345
alexander-akait merged 2 commits into
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fix/report-removal-after-start-time

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