[alexander-akait]

Fixes #228. Supersedes #229.

On macOS and Windows, import B from "./B" resolves when the file is b.js, and webpack watches .../B.js. watchpack already sends change events to that watcher, because watchers are keyed without case. But collectTimeInfoEntries only matches exact case, so B.js gets null ("missing"). webpack stores that null in the module's snapshot, and on the next edit null === null looks unchanged. The first edit rebuilds and later ones don't.

Fix: a watched path that is missing from files, but matches a file there apart from case, gets that file's entry. This happens only on a case-insensitive file system. Whether the directory ignores case is learned once, the first time such a mismatch occurs: lstat both names and compare inode and device. On Linux the other-case name fails to lstat, so it stays null. Missing dependencies (resolution candidates) are therefore never reported as existing, which is the problem with #229's unconditional lowercase match.

Behaviour change: after a case-only rename (hello.txt → hEllO.txt), a watcher for hello.txt now gets the renamed file's entry instead of null. On a case-insensitive file system that name still opens the file. Reporting null caused the same stale-snapshot bug. The existing casing test is updated to match.

Verified in CI (temporary jobs, since removed)

webpack in watch mode, importing ./B for b.js and editing it 3 times:

watchpack	macOS outputs	Windows outputs
main	v0, v1, v1 ❌	v0, v0, v0, v0 ❌
this PR	v0, v1, v2, v3 ✅	v0, v0, v1, v2, v3 ✅

webpack's WatchTestCases, WatchCacheUnaffectedTestCases and watch unit tests with this lib: 5,232 passed on Linux, passed on Windows, 5,231 passed on macOS. The single macOS failure, NodeWatchFileSystem › shares one watcher pool between equal options (expects 1 directory watcher, gets 8), fails the same way with the published watchpack 2.6.1. It comes from macOS watching parent directories, and webpack runs its unit tests on Linux only.

Tests

• A new casing test (it runs where the file system ignores case: macOS and Windows CI): a file watched as A while a exists gets a's entry, and the entry follows edits.
• A new case-sensitive test (Linux): A stays null.
• Full suite 206/206 locally, lint clean.

🤖 Generated with Claude Code

https://claude.ai/code/session_017TkBWTk3wcyUcJYDp5ZhaP

Summary by CodeRabbit

• Bug Fixes
  • Fixed file watching on case-insensitive file systems when a file is referenced with different capitalization. File changes are now detected consistently, so rebuilds continue after the first change.

[changeset-bot]

🦋 Changeset detected

Latest commit: 1be3435

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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[codspeed]

Merging this PR will not alter performance

⚠️ 1 benchmark 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

• ignored-cross-platform: regex against windows paths

✅ 36 untouched benchmarks

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_{Comparing fix/case-insensitive-time-info (1be3435) with main (6695b9f)}

[codecov]

Codecov Report

❌ Patch coverage is 96.29630% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 92.65%. Comparing base (6695b9f) to head (1be3435).

Files with missing lines	Patch %	Lines
lib/DirectoryWatcher.js	96.29%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #358      +/-   ##
==========================================
+ Coverage   92.58%   92.65%   +0.06%     
==========================================
  Files           8        8              
  Lines        1363     1389      +26     
  Branches      405      416      +11     
==========================================
+ Hits         1262     1287      +25     
- Misses         95       96       +1     
  Partials        6        6              

Flag	Coverage Δ
integration	92.65% <96.29%> (+0.06%)	⬆️

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ℹ️ Recent review info

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• Configuration used: Organization UI
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• Run ID: b8416e30-7b6f-42a3-8819-e3987e77ae3a

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Reviewing files that changed from the base of the PR and between 36454df and 1be3435.

📒 Files selected for processing: 2

• lib/DirectoryWatcher.js
• test/DirectoryWatcherExtra.test.js

🚧 Files skipped from review as they are similar to previous changes: 1

• lib/DirectoryWatcher.js

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Walkthrough

DirectoryWatcher now tracks whether its directory is case-sensitive. When a watched path is absent from the timestamp map, it checks whether a differently cased tracked path identifies the same file. If the filesystem is case-insensitive, it uses that path’s time-info entry. Tests cover timestamp updates on case-insensitive filesystems, missing paths on case-sensitive filesystems, and deferred detection after a stat error. The change also adds type declarations and a patch changeset.

Priority: ➖ Normal

Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to 1be34

The change gives differently cased watched paths the time info of their file on case-insensitive file systems. A transient stat error now defers detection instead of fixing the wrong result. No merge-blocking risk is identified.

Pre-merge checks: 5

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 fix for differently cased paths on case-insensitive file systems.
Linked Issues check		PASS. The changes address issue [#228]. DirectoryWatcher matches a missing watched path to a file with different casing only after lstat checks establish a case-insensitive file system. The case-s…
Out of Scope Changes check		PASS. The changes stay within issue [#228]. The implementation, declaration updates, regression tests, transient-error coverage, and changeset support case-aware time-info collection and its rebuild b…
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 4…

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Actionable comments posted: 1

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ℹ️ Review info

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• .changeset/case-insensitive-time-info.md
• lib/DirectoryWatcher.js
• test/Casing.test.js
• types/DirectoryWatcher.d.ts

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