# Resolution Summary

**Branch**: chore/cochange-review-fixes
**Review**: main-cochange-353ef87/2026-05-24_2305
**Date**: 2026-05-24
**Cycle**: 1

## Statistics

| Outcome | Count |
|---------|-------|
| Fixed | 18 |
| False Positive | 0 |
| Deferred | 0 |
| **Total** | **18** |

## Resolved Issues

### Batch 1: builder.rs + types.rs (8 fixes)

| Issue | Severity | File | Fix |
|-------|----------|------|-----|
| Double HashMap lookup in hot loop | HIGH | builder.rs:184-191 | Replaced `contains_key()` + `entry()` with Entry API single-probe pattern |
| `IndexCorrupted` semantic mismatch | MEDIUM | types.rs, builder.rs | Added `SearchError::CapacityExceeded` variant; updated all capacity-limit errors |
| Redundant min/max after sort+dedup | MEDIUM | builder.rs:179-180 | Direct assignment `let a = ids[i]; let b = ids[j]` |
| Missing sync_all() before persist | MEDIUM | builder.rs:297 | Added `tmp.as_file().sync_all()?` before persist |
| Stats unwrap_or(u32::MAX) | MEDIUM | builder.rs:106-107 | Replaced with `map_err` pattern matching serialize() |
| accumulate_pairs length (73 lines) | MEDIUM | builder.rs:132-206 | Extracted `generate_pairs()` helper |
| serialize length (79 lines) | MEDIUM | builder.rs:209-288 | Extracted `collect_sorted_file_entries()` and `collect_sorted_pair_entries()` |
| HashMap capacity overestimate | MEDIUM | builder.rs:137 | Changed to `history.commits.len().min(max_pairs / 4)` |

### Batch 2: reader.rs (3 fixes)

| Issue | Severity | File | Fix |
|-------|----------|------|-----|
| pairs_for_file O(n) linear scan | HIGH | reader.rs:189-208 | Binary search for file_a range start; linear scan only within relevant range |
| Mmap SAFETY comment incomplete | MEDIUM | reader.rs:22-25, 74-75 | Documented atomic-rename mitigation and Windows caveat |
| Redundant #[must_use] on Result methods | MEDIUM | reader.rs:69,135,154 | Removed from 3 Result-returning methods |

### Batch 3: format.rs + mod.rs (3 fixes)

| Issue | Severity | File | Fix |
|-------|----------|------|-----|
| Sub-module visibility mismatch | MEDIUM | mod.rs:24-26 | Changed `pub(crate) mod` to `mod` matching index pattern |
| CRC32 doc missing limitations | MEDIUM | format.rs:283-288 | Added note that CRC32 is not tamper-resistant |
| Redundant #[must_use] on builder | MEDIUM | builder.rs:51,76 | Removed from 2 Result-returning methods |

### Batch 4: test files (4 fixes)

| Issue | Severity | File | Fix |
|-------|----------|------|-----|
| Missing truncated-input tests | MEDIUM | format_tests.rs | Added `test_file_commit_entry_truncated` and `test_pair_entry_truncated` |
| Missing size-mismatch test | MEDIUM | reader_tests.rs | Added `test_open_size_mismatch_detected` |
| Misleading test name | LOW | reader_tests.rs:150 | Renamed to `test_jaccard_no_shared_commits_returns_zero` |
| Conditional guard in CRC test | LOW | reader_tests.rs:261 | Replaced `if data.len() > 20` with assert + HEADER_SIZE constant |

## Commits

1. `d02c647` refactor(cochange): apply batch-1 review fixes
2. `75b56a2` fix(cochange): optimize pairs_for_file, fix SAFETY docs, remove redundant #[must_use]
3. `24b4cb6` refactor(cochange): batch-3-format-mod review fixes
4. `38a97b0` test(cochange): add missing truncation and size-mismatch coverage

## Verification

- Tests: 357 pass, 0 fail, 3 skip
- Clippy: 0 warnings, 0 errors
