Core: Normalize file paths in ChangeDetectionService and trace-changed for Windows support

[ghengeveld]

What I did

Normalize paths in change detection and module tracing logic to support Windows.

Checklist for Contributors

Testing

The changes in this PR are covered in the following automated tests:

• stories
• unit tests
• integration tests
• end-to-end tests

Manual testing

Caution

This section is mandatory for all contributions. If you believe no manual test is necessary, please state so explicitly. Thanks!

Documentation

• Add or update documentation reflecting your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Checklist for Maintainers

• When this PR is ready for testing, make sure to add ci:normal, ci:merged or ci:daily GH label to it to run a specific set of sandboxes. The particular set of sandboxes can be found in code/lib/cli-storybook/src/sandbox-templates.ts

• Make sure this PR contains one of the labels below:

  Available labels

  • bug: Internal changes that fixes incorrect behavior.
  • maintenance: User-facing maintenance tasks.
  • dependencies: Upgrading (sometimes downgrading) dependencies.
  • build: Internal-facing build tooling & test updates. Will not show up in release changelog.
  • cleanup: Minor cleanup style change. Will not show up in release changelog.
  • documentation: Documentation only changes. Will not show up in release changelog.
  • feature request: Introducing a new feature.
  • BREAKING CHANGE: Changes that break compatibility in some way with current major version.
  • other: Changes that don't fit in the above categories.

🦋 Canary release

This PR does not have a canary release associated. You can request a canary release of this pull request by mentioning the @storybookjs/core team here.

core team members can create a canary release here or locally with gh workflow run --repo storybookjs/storybook publish.yml --field pr=<PR_NUMBER>

Summary by CodeRabbit

• Bug Fixes

  • Standardized path handling to ensure changed and newly indexed story files are detected consistently across platforms and to eliminate a duplicate/new-file indexing inconsistency.

• Tests

  • Updated tests to use the same normalized path approach and validate change-detection behavior remains correct.

[nx-cloud]

View your CI Pipeline Execution ↗ for commit a09cdf6

Command	Status	Duration	Result
nx run-many -t compile,check,knip,test,lint,fmt...	✅ Succeeded	6m 24s	View ↗

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☁️ Nx Cloud last updated this comment at 2026-04-07 12:09:08 UTC

[coderabbitai]

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📝 Walkthrough

Walkthrough

Changed path handling in change-detection: replaced absolute resolution with pathe.join for story/module keys, switched scanned/new/changed file set construction to use repo-root-joined or pathe.relative, removed custom toRepoRelativePath, and updated tests to use pathe.join and shared path variables. Also introduced a duplicated newFiles assignment in the diff.

Changes

Cohort / File(s)	Summary
ChangeDetection service code/core/src/core-server/change-detection/ChangeDetectionService.ts	Replaced node:path.resolve(workingDir, ...) with pathe.join(workingDir, ...) for story/module keys; changed scanned/new/changed file set creation to use pathe.join(repoRoot, filePath) and pathe.relative(repoRoot, changedFile); removed toRepoRelativePath() (including its Windows \\\\?\\ handling); diff includes a duplicated newFiles assignment altering how newFiles is built.
Tests — change-detection code/core/src/core-server/change-detection/ChangeDetectionService.test.ts	Switched test import to pathe, introduced shared path variables (buttonCssPath, buttonComponentPath, buttonStoryPath) and reused them for createModuleNode(...) and ModuleGraph keys to match new join/relative behavior; assertions unchanged.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• Core: Implement Git change detection #34420 — Modifies ChangeDetectionService and repo-relative/absolute path handling; closely related to the path-resolution changes here.
• Core: Improve file path resolution on Windows #32893 — Replaces Node path APIs with pathe in core-server path handling; overlaps with this PR's migration to pathe.join.
• Build: Fix build on windows #33224 — Similar replacements of Node path functions with pathe.join across core code; likely to touch related path normalization logic.

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[coderabbitai]

🧹 Nitpick comments (1)

code/core/src/core-server/change-detection/trace-changed.ts (1)

5-21: Well-structured fallback lookup for cross-platform compatibility.

The two-phase approach is sound: direct O(1) lookup first, then O(n) fallback only when needed. This handles module graphs where keys might have inconsistent path formats (e.g., Windows backslashes vs. forward slashes).

Consider adding a brief inline comment explaining when the fallback is expected to trigger (e.g., Windows paths in moduleGraph keys).

📝 Optional: Add explanatory comment

 function getModuleNodesByNormalizedPath(
   moduleGraph: ModuleGraph,
   normalizedPath: string
 ): Set<ModuleNode> | undefined {
   const directMatch = moduleGraph.get(normalizedPath);
   if (directMatch) {
     return directMatch;
   }
 
+  // Fallback: moduleGraph keys may use OS-native separators (e.g., backslashes on Windows)
   for (const [modulePath, nodes] of moduleGraph.entries()) {
     if (normalizePath(modulePath) === normalizedPath) {
       return nodes;
     }
   }
 
   return undefined;
 }

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@code/core/src/core-server/change-detection/trace-changed.ts` around lines 5 -
21, Add a short inline comment in getModuleNodesByNormalizedPath explaining that
after the O(1) direct lookup the O(n) fallback scans moduleGraph entries to
handle mismatched path formats (e.g., Windows backslashes vs POSIX forward
slashes) and will only run when keys in moduleGraph are not already normalized;
place the comment above the fallback for clarity so future readers understand
when and why the fallback path is expected to trigger.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@code/core/src/core-server/change-detection/trace-changed.ts`:
- Around line 5-21: Add a short inline comment in getModuleNodesByNormalizedPath
explaining that after the O(1) direct lookup the O(n) fallback scans moduleGraph
entries to handle mismatched path formats (e.g., Windows backslashes vs POSIX
forward slashes) and will only run when keys in moduleGraph are not already
normalized; place the comment above the fallback for clarity so future readers
understand when and why the fallback path is expected to trigger.

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📥 Commits

Reviewing files that changed from the base of the PR and between c2bcb9d and b14cbbd.

📒 Files selected for processing (2)

• code/core/src/core-server/change-detection/ChangeDetectionService.ts
• code/core/src/core-server/change-detection/trace-changed.ts