# Regression Review Report

**Branch**: feat/176-tmux-abstraction-layer -> main
**Date**: 2026-05-17T21:45:00Z
**Scope**: 5 commits (40f9537...HEAD) — style simplifications, bug fixes, test additions

## Issues in Your Changes (BLOCKING)

### CRITICAL

(none)

### HIGH

(none)

## Issues in Code You Touched (Should Fix)

(none)

## Pre-existing Issues (Not Blocking)

(none)

## Suggestions (Lower Confidence)

(none)

## Analysis Summary

All 5 changes in this incremental diff were analyzed for regression risk:

### 1. Removed `stopSharedStalenessTimerIfEmpty()` — NO REGRESSION
**Confidence**: 95% safe
- Replaced by `restartSharedStalenessTimer()` in `destroy()` and `triggerExit()`.
- `restartSharedStalenessTimer()` already calls `stopSharedStalenessTimer()` first, then returns early if `activeSessions.size === 0` — equivalent behavior when empty.
- When NOT empty (multi-session case), the replacement is strictly better: it recalculates the minimum interval for remaining sessions instead of leaving the timer running at the old interval. The old `stopSharedStalenessTimerIfEmpty` was a no-op in this case, meaning remaining sessions could be polled at a rate determined by an already-removed session.
- No external consumers of the removed private method.

### 2. `handleMessageFile` unhandled promise rejection fix — NO REGRESSION
**Confidence**: 98% safe
- `handleMessageFile()` was already `async` (returns `Promise<void>`), but was called from a `setTimeout` callback without `.catch()`, producing silent unhandled promise rejections.
- The `.catch()` handler logs a warning and does not change the control flow for successful calls.
- This is a pure bug fix — no behavior change for the success path.

### 3. `hooks.cleanup()` Result error handling (4 call sites) — NO REGRESSION
**Confidence**: 97% safe
- Previously, `hooks.cleanup()` returned `Result<void, AutobeatError>` but the result was discarded at all 4 call sites (spawn failure, destroy, dispose, triggerExit).
- Now the result is checked and failures are logged with `logger.warn()`.
- No behavior change: cleanup failure is still non-blocking. The only addition is observability.

### 4. Map mutation-during-iteration fix in `runSharedStalenessCheck` — NO REGRESSION
**Confidence**: 99% safe (correctness fix)
- Old code called `triggerExit()` inside a `for...of` loop over `this.activeSessions`, but `triggerExit()` calls `this.activeSessions.delete()` — mutating the Map during iteration.
- JavaScript Map iteration is defined to skip entries deleted during iteration, so if multiple sessions went stale simultaneously, some could be missed.
- New code collects stale entries into a separate array first, then processes them. This is strictly more correct.

### 5. `MIN_CHECK_INTERVAL_MS` floor (1000ms) — NO REGRESSION
**Confidence**: 95% safe
- Clamps `checkIntervalMs` to a minimum of 1000ms to prevent tight-loop `setInterval`.
- Default `checkIntervalMs` is 30,000ms. All existing tests use >= 1000ms.
- This is a defensive guardrail — no existing caller would pass < 1000ms in production.

### 6. `SAFE_PATH_REGEX` moved from `tmux-hooks.ts` to `types.ts` — NO REGRESSION
**Confidence**: 100% safe
- The regex was a module-private `const` in `tmux-hooks.ts` and is now an exported `const` in `types.ts`.
- `tmux-hooks.ts` imports it from `types.ts`.
- The barrel `index.ts` re-exports it.
- The regex value is identical: `/^[a-zA-Z0-9/_.\-]+$/`.
- No external consumers outside the tmux module.

### 7. JSDoc comment fix ("double-quoted" -> "single-quoted") — NO REGRESSION
**Confidence**: 100% safe
- Comment-only change in `tmux-hooks.ts` line 10. The wrapper script already used single quotes; the JSDoc was stale.

### 8. Extracted helper methods (buildActiveSession, startSentinelWatcher, startMessagesWatcher, forceDeliverRemaining) — NO REGRESSION
**Confidence**: 97% safe
- Pure refactoring extractions. All logic is identical to the inlined versions.
- `forceDeliverRemaining`: uses `session.pendingMessages.delete(seq)` instead of `session.pendingMessages.delete(msg.sequence)` — equivalent because the Map key `seq` equals `msg.sequence` by construction.
- All 45 tests pass including flush, ordering, and edge case coverage.

### 9. Test mock additions (`on: vi.fn()`) — NO REGRESSION
**Confidence**: 100% safe
- Added `on: vi.fn()` to mock watchers because the new code calls `.on('error', ...)` on watchers.
- Without this, existing tests would crash on the mock. This is a necessary mock update, not a test weakening.
- 4 new test cases added covering watcher errors, alive-session heartbeat, cleanup-on-destroy, and cleanup-on-dispose.

## Summary

| Category | CRITICAL | HIGH | MEDIUM | LOW |
|----------|----------|------|--------|-----|
| Blocking | 0 | 0 | 0 | - |
| Should Fix | - | 0 | 0 | - |
| Pre-existing | - | - | 0 | 0 |

**Regression Score**: 10/10
**Recommendation**: APPROVED

All changes in this incremental diff are either correctness fixes (Map mutation during iteration, unhandled promise rejection, cleanup result handling), defensive guardrails (MIN_CHECK_INTERVAL_MS), or pure refactoring extractions. No exports were removed, no function signatures changed, no return types were altered, and no behavior was broken. All 45 tests pass.
