perf(web): speed up diff file sorting

[CouchRiv]

What Changed

DiffPanel repeats locale setup while comparing file paths in a patch. Create an Intl.Collator on the first comparison and reuse it for the rest of the sort, with the existing default locale, numeric ordering, and base sensitivity. This applies the folder-menu optimization from #10190 to the diff panel.

Why

Sorting 500 tracked repository paths in Git order took 5.48 ms before and 0.11 ms after in a warmed Node 24.14.0 benchmark on Windows (median of 25 batches). This compares the actual memo bodies using synthetic patches; it measures sorting, excluding parsing and rendering.

Verification

• Output matched the baseline for numeric names, case/leading-zero ties, Unicode paths, and renamed/deleted files; the input array stayed unchanged.
• diffRendering.test.ts and diffFileTree.logic.test.ts: 14 tests passed.
• Web typecheck, targeted formatting, and git diff --check passed. Targeted lint reports only two warnings reproduced on the original file.

Checklist

• This PR is small and focused
• I explained what changed and why

No appearance or interaction changes.

Implemented with GPT-6 through Codex desktop.

Summary by CodeRabbit

• Performance
  • Improved file path sorting efficiency in the diff panel while preserving the existing sort order.

[macroscopeapp]

Approvability

Verdict: Would Approve

Macroscope's review found this PR approvable — This is a focused six-line optimization of existing diff-file sorting that reuses an equivalent collator configuration and does not introduce new user-facing behavior or broader system changes. Its runtime impact is limited to reducing sorting overhead in the existing DiffPanel path.

Not approved because:

• Monthly spending limit reached (workspace setting). Approvability relies on correctness review in order to determine eligibility

No code changes detected at 3bf7b33. Prior analysis still applies.

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[coderabbitai]

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between de28fa1 and 2bd1022.

📒 Files selected for processing (1)

• apps/web/src/components/DiffPanel.tsx

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📝 Walkthrough

Walkthrough

DiffPanel now caches an Intl.Collator for file path sorting. The collator preserves numeric and case-insensitive comparison behavior.

Changes

DiffPanel sorting

Layer / File(s)	Summary
Cache the file path collator apps/web/src/components/DiffPanel.tsx	renderableFiles uses a lazily initialized Intl.Collator with numeric: true and sensitivity: "base" for path comparisons.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Merge Risk: ⚪ Minimal · up to 2bd10

Diff file paths are now sorted with a reused collator to improve rendering performance while retaining existing ordering behavior. The change is ready to merge with no current-head merge-blocking risk identified.

Suggested reviewers: juliusmarminge, maria-rcks, stienswout

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 1 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: improving diff file sorting performance.
Description check	✅ Passed	The description includes the required What Changed and Why sections, explains the optimization, documents verification results, and addresses the absence of UI or interaction changes. The checklist ac…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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