# Tasks: Pre-Commit Gate

**Input**: Design documents from `/specs/006-pre-commit-gate/`
**Prerequisites**: plan.md (required), spec.md (required for user stories), research.md, quickstart.md

**Tests**: No test tasks included (not requested in feature specification). Verification is manual.

**Organization**: Tasks are grouped by user story to enable independent implementation and testing of each story.

## Format: `[ID] [P?] [Story] Description`

- **[P]**: Can run in parallel (different files, no dependencies)
- **[Story]**: Which user story this task belongs to (e.g., US1, US2, US3)
- Include exact file paths in descriptions

## Phase 1: Setup (Shared Infrastructure)

**Purpose**: Install Lefthook and configure auto-install mechanism

- [x] T001 Add `lefthook` as a devDependency and add a `prepare` script that runs `lefthook install` in `package.json`
- [x] T002 Run `pnpm install` to install lefthook and activate the prepare script

**Checkpoint**: `lefthook` is installed and `pnpm install` triggers `lefthook install` automatically

---

## Phase 2: User Story 1 & 2 - Block Failing / Allow Passing Commits (Priority: P1) MVP

**Goal**: Create the Lefthook pre-commit hook configuration that runs `pnpm check`, blocking commits on failure and allowing commits on success.

**Independent Test (US1)**: Introduce a deliberate lint error, run `git commit`, and verify the commit is blocked with visible error output.

**Independent Test (US2)**: Make a valid change, run `git commit`, and verify the commit succeeds after `pnpm check` passes.

### Implementation

- [x] T003 [US1] [US2] Create `lefthook.yml` at repository root with a `pre-commit` hook that runs `pnpm check`

**Checkpoint**: Commits are blocked when `pnpm check` fails (US1) and allowed when it passes (US2). Output from `pnpm check` is visible to the developer.

---

## Phase 3: User Story 3 - Bypass Gate in Emergencies (Priority: P2)

**Goal**: Ensure the standard `git commit --no-verify` flag bypasses the pre-commit hook.

**Independent Test**: Stage a change that would fail checks, run `git commit --no-verify`, and verify the commit succeeds without running checks.

### Implementation

No implementation task needed -- Lefthook respects `--no-verify` by default (standard Git behavior). This phase exists for verification only.

**Checkpoint**: `git commit --no-verify` bypasses the pre-commit gate.

---

## Phase 4: Polish & Cross-Cutting Concerns

**Purpose**: Edge case handling and validation

- [x] T004 Verify the hook provides a clear error when `pnpm` is not in PATH (FR-007) and when `node_modules` are missing (edge case)
- [x] T005 Run quickstart.md validation: clone-install-commit workflow works end-to-end (SC-003)

---

## Dependencies & Execution Order

### Phase Dependencies

- **Setup (Phase 1)**: No dependencies -- start immediately
- **US1 & US2 (Phase 2)**: Depends on Phase 1 (lefthook must be installed)
- **US3 (Phase 3)**: No implementation needed -- verify after Phase 2
- **Polish (Phase 4)**: Depends on Phase 2 completion

### Parallel Opportunities

- T001 and T003 touch different files (`package.json` vs `lefthook.yml`) but T003 depends on lefthook being installed, so they must be sequential.
- T004 and T005 can run in parallel after Phase 2.

---

## Implementation Strategy

### MVP First (User Stories 1 & 2)

1. Complete Phase 1: Install lefthook + prepare script
2. Complete Phase 2: Create `lefthook.yml` with pre-commit hook
3. **STOP and VALIDATE**: Test both blocking and allowing commits
4. Verify US3 bypass works (no implementation needed)

### Execution Summary

Total: **5 tasks** across 4 phases
- Phase 1 (Setup): 2 tasks
- Phase 2 (US1 + US2): 1 task
- Phase 3 (US3): 0 tasks (verification only)
- Phase 4 (Polish): 2 tasks

---

## Notes

- US1 and US2 are implemented by the same single task (T003) because they are two sides of the same coin: the hook either blocks or allows based on `pnpm check` exit code.
- US3 requires no implementation -- `--no-verify` is standard Git behavior that Lefthook respects.
- This is a minimal-footprint feature: 1 new file (`lefthook.yml`), 1 modified file (`package.json`).