[codex] Harden Windows file indexing and UserAssist parsing

[tianmind-studio]

Summary

• Skip file-index noise directories case-insensitively so Windows paths like .GIT, Node_Modules, or __PYCACHE__ do not get scanned.
• Keep the exported SKIP_DIRS entries verbatim while using an internal normalized set for case-insensitive matching.
• Parse UserAssist run/focus counters as unsigned DWORD values so long-lived Windows usage history cannot wrap into negative focus time.
• Add focused unit coverage for both Windows edge cases.
• Format the touched UserAssist edge-case test with the current Windows app dev dependencies.

Why

Windows directory matching is case-insensitive in practice, but the scan skip list was case-sensitive. UserAssist binary fields are DWORD counters; reading them as signed integers can make high-bit values negative, which would corrupt seeded usage ranking for long-lived installs.

Refresh

• Rebased on main at 1a5824403b.
• Current head: 86dfe2e724.
• The Greptile concern about exporting pre-normalized SKIP_DIRS is already addressed; the review thread is resolved/outdated.

Validation

• vitest run src/main/fileIndex/scanRules.test.ts src/main/usage/userAssist.test.ts -> 2 files passed, 22 tests passed
• npm run typecheck -> passed
• prettier --check src/main/fileIndex/scanRules.ts src/main/fileIndex/scanRules.test.ts src/main/usage/userAssist.ts src/main/usage/userAssist.test.ts -> passed
• git diff --check origin/main...HEAD
• scripts/pre-commit with the backend Windows venv and local Dart SDK on PATH

[greptile-apps]

Greptile Summary

This PR hardens two Windows-specific parsing paths: file-index directory skipping is made case-insensitive (fixing missed skips for paths like Node_Modules or .GIT), and UserAssist registry DWORD fields are read as unsigned integers instead of signed, preventing negative focus-time values on long-lived installs. Both fixes are accompanied by focused unit tests.

• scanRules.ts: shouldVisitDir now calls .toLowerCase() before the SKIP_DIRS set lookup; set entries are normalized to lowercase accordingly.
• userAssist.ts: readInt32LE → readUInt32LE for runCount, focusCount, and focusMs, correctly reflecting the Windows DWORD type (values up to ~4.3 billion no longer wrap negative).
• Test helpers in userAssist.test.ts are updated to use writeUInt32LE, and new cases exercise values above INT32_MAX to directly prove the fix.

Confidence Score: 4/5

Both changes are narrow, well-targeted fixes with matching unit tests; the only thing to double-check is the exported SKIP_DIRS constant whose entries are now pre-lowercased.

The unsigned-read change in userAssist.ts is straightforward and the new test directly exercises values that would have produced negatives before. The case-insensitive directory skipping works correctly for all callers of shouldVisitDir. The sole concern is that the exported SKIP_DIRS constant silently changed its entry casing — any future direct consumer calling .has(name) without normalising first would get wrong results, but no such consumer exists today.

scanRules.ts — the exported SKIP_DIRS constant now holds pre-lowercased strings, which is invisible from the type signature.

Important Files Changed

Filename	Overview
desktop/windows/src/main/fileIndex/scanRules.ts	Added .toLowerCase() to shouldVisitDir for case-insensitive matching and normalised SKIP_DIRS entries to lowercase; exported constant now silently requires pre-normalised lookups.
desktop/windows/src/main/usage/userAssist.ts	Switched readInt32LE → readUInt32LE for runCount, focusCount, and focusMs fields; correctly treats Windows DWORD counters as unsigned so high-bit values no longer produce negative numbers.
desktop/windows/src/main/fileIndex/scanRules.test.ts	Adds a test block covering Node_Modules, .GIT, and __PYCACHE__ mixed-case inputs; pairs correctly with the implementation change.
desktop/windows/src/main/usage/userAssist.test.ts	Test helper blob() updated to use writeUInt32LE; new test covers values > INT32_MAX (3B/4B) to directly validate the unsigned-read fix.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[Directory entry name] --> B["name.toLowerCase()"]
    B --> C{SKIP_DIRS.has?}
    C -- yes --> D[Skip directory]
    C -- no --> E{depth <= MAX_DEPTH?}
    E -- yes --> F[Descend into directory]
    E -- no --> G[Stop recursion]

    H[UserAssist registry blob] --> I["readUInt32LE(OFF_RUN_COUNT)"]
    H --> J["readUInt32LE(OFF_FOCUS_COUNT)"]
    H --> K["readUInt32LE(OFF_FOCUS_MS)"]
    I --> L[runCount: 0..4294967295]
    J --> M[focusCount: 0..4294967295]
    K --> N["focusSeconds = round(focusMs / 1000)"]
    N --> O[Aggregate by friendly app name]
    O --> P[Sort by focusSeconds desc]

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_{Reviews (1): Last reviewed commit: "fix(windows): harden file index and User..." | Re-trigger Greptile}