# Regression Review Report

**Branch**: feat/176-tmux-abstraction-layer -> main
**Date**: 2026-05-18
**Commits reviewed**: 20 (a10a9e0..d2cd5dc)

## Scope

This branch adds a new tmux abstraction layer under `src/implementations/tmux/` with 16 new files (source + tests) and modifies 3 existing files:

| Modified file | Change type |
|---------------|-------------|
| `src/core/errors.ts` | Additive: 4 new ErrorCode enum values + 4 factory functions |
| `package.json` | Additive: 2 new test scripts, 2 exclusion patterns, `test:all` extended |
| `.features/index.json` | Additive: 2 new feature knowledge entries |

## Issues in Your Changes (BLOCKING)

### CRITICAL

(none)

### HIGH

(none)

### MEDIUM

**`test` warning message does not list new safe commands** - `package.json:19`
**Confidence**: 82%

- Problem: The `npm test` warning message lists safe commands for Claude Code users, but `test:tmux` and `test:tmux:integration` are not included in that list. Developers running `npm test` will not know about these new safe test groups.
- Impact: Developer experience issue. Claude Code users may not discover the new tmux test scripts are available as safe commands.
- Fix: Add `npm run test:tmux` and `npm run test:tmux:integration` to the safe commands list in the `test` script echo message. Alternatively, this could be deferred to a CLAUDE.md update in a follow-up.

## Issues in Code You Touched (Should Fix)

(none)

## Pre-existing Issues (Not Blocking)

(none)

## Suggestions (Lower Confidence)

(none)

## Regression Checklist

| Check | Status | Notes |
|-------|--------|-------|
| No exports removed | PASS | 0 removed exports; 4 new ErrorCode values + 4 factory functions added |
| Return types backward compatible | PASS | No existing signatures modified |
| Default values unchanged | PASS | No existing defaults modified |
| Side effects preserved | PASS | No existing event handlers or logging changed |
| All consumers of changed code updated | PASS | New error codes only used within new tmux module |
| No deleted files | PASS | 0 files deleted |
| CLI options preserved | PASS | No CLI changes |
| API endpoints preserved | PASS | No MCP adapter changes |
| Commit messages match implementation | PASS | All 20 commits accurately describe their changes |
| Breaking changes documented | N/A | No breaking changes |

## Detailed Analysis

### `src/core/errors.ts` — No Regression

The existing 29 ErrorCode enum values are preserved in their original order. Four new values appended at the end of the enum:
- `TMUX_SESSION_FAILED`
- `TMUX_VALIDATION_FAILED`
- `TMUX_HOOK_FAILED`
- `TMUX_SEND_KEYS_FAILED`

Four new factory functions appended after existing factories:
- `tmuxSessionFailed`
- `tmuxValidationFailed`
- `tmuxHookFailed`
- `tmuxSendKeysFailed`

All existing exports (16 on main) are preserved. Branch has 20 exports (net +4). No signatures changed, no return types widened. This is a clean additive extension.

### `package.json` — No Regression (1 minor gap)

**`test:all`**: Extended with `&& npm run test:tmux && npm run test:tmux:integration` at the end. Existing test groups remain in the same order. No removals.

**`test:implementations`**: Added `--exclude='**/tmux/**'` to prevent double-counting tmux tests (they have their own dedicated group). This correctly isolates the new tests without affecting existing implementation tests.

**`test:integration`**: Added `--exclude='**/tmux/**'` for the same reason. Existing non-tmux integration tests are unaffected.

**New scripts**: `test:tmux` and `test:tmux:integration` added. These are additive and don't conflict with existing scripts.

The one gap: the `npm test` warning message does not list these new scripts as safe commands (MEDIUM, see above).

### `.features/index.json` — No Regression

Changed from `{"version":1,"features":{}}` (empty) to include 2 feature knowledge entries. The `version` field is preserved at `1`. This is a devflow metadata file with no runtime impact.

### Barrel Exports (`src/implementations/tmux/index.ts`) — New File, No Regression

All public types from `types.ts` (19 types + 8 constants) are properly re-exported. `SpawnCallbacks` is re-exported via `tmux-connector.js` (which itself re-exports from `types.js`), while `TmuxConnectorPort` is re-exported directly from `types.js`. Both paths resolve to the same `types.ts` definitions. No duplicate runtime exports.

### No External Consumers Yet

No existing source files import from the new tmux module. The new error codes are used exclusively within `src/implementations/tmux/`. This confirms the feature is self-contained with zero coupling to existing modules, making regression risk minimal.

## Summary

| Category | CRITICAL | HIGH | MEDIUM | LOW |
|----------|----------|------|--------|-----|
| Blocking | 0 | 0 | 1 | 0 |
| Should Fix | 0 | 0 | 0 | 0 |
| Pre-existing | 0 | 0 | 0 | 0 |

**Regression Score**: 9/10
**Recommendation**: APPROVED_WITH_CONDITIONS

The single condition: update the `npm test` warning message to include `test:tmux` and `test:tmux:integration` in the safe commands list, or document them in CLAUDE.md. This is a MEDIUM developer experience gap, not a functional regression.

All existing exports, signatures, defaults, and behavior are preserved. The branch is purely additive with no breaking changes to existing consumers.
