Implement the 007-add-knip feature that adds Knip unused code detection to the quality gate and as a standalone command

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

specs/007-add-knip/tasks.md

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+# Tasks: Add Knip Unused Code Detection
+
+**Input**: Design documents from `/specs/007-add-knip/`
+**Prerequisites**: plan.md (required), spec.md (required), research.md, data-model.md, quickstart.md
+
+**Tests**: No automated test tasks — this is a tooling feature validated by running `pnpm knip` and `pnpm check`.
+
+**Organization**: Tasks follow the two user stories (US1: quality gate enforcement, US2: standalone command).
+
+## 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)
+- Include exact file paths in descriptions
+
+## Phase 1: Setup
+
+**Purpose**: Install Knip and create configuration
+
+- [x] T001 Install Knip v5 as a root devDependency via `pnpm add -Dw knip`
+- [x] T002 Create `knip.json` at the repository root with workspace-aware configuration covering `packages/*` and `apps/*`, including `$schema` for editor support
+
+---
+
+## Phase 2: Foundational (Blocking Prerequisites)
+
+**Purpose**: Ensure Knip passes cleanly on the current codebase before integrating into the gate
+
+**CRITICAL**: Must resolve all false positives before wiring into the quality gate
+
+- [x] T003 Run `pnpm knip` against the current codebase and capture output
+- [x] T004 If false positives are reported, tune `knip.json` with `ignore`, `ignoreDependencies`, `entry`, or plugin-specific overrides until the codebase passes cleanly (FR-006 through FR-009)
+
+**Checkpoint**: `pnpm knip` exits with code 0 on the current codebase (SC-002)
+
+---
+
+## Phase 3: User Story 1 - Detect Unused Code on Commit (Priority: P1)
+
+**Goal**: Integrate Knip into the `pnpm check` quality gate so unused code is caught on every commit via Lefthook.
+
+**Independent Test**: Introduce an unused export in any workspace package, run `pnpm check`, and confirm it fails with a clear report. Remove the unused export and confirm `pnpm check` passes.
+
+### Implementation for User Story 1
+
+- [x] T005 [US1] Update the `check` script in `package.json` to prepend `knip &&` before `biome check .` so unused code is checked as part of the quality gate
+- [x] T006 [US1] Run `pnpm check` end-to-end and verify it passes on the current codebase (SC-001, SC-002)
+- [x] T007 [US1] Manually verify detection: (a) add a temporary unused export to `packages/domain/src/index.ts`, run `pnpm check`, confirm it fails with a report identifying the unused export and its file location (SC-001, SC-004), then remove the temporary change; (b) verify that exports re-exported through barrel files (e.g., `index.ts`) are correctly traced and not falsely flagged
+
+**Checkpoint**: Quality gate enforces unused-code detection on every commit. US1 acceptance scenarios 1–5 are satisfied.
+
+---
+
+## Phase 4: User Story 2 - Run Unused-Code Check Independently (Priority: P2)
+
+**Goal**: Provide a standalone `pnpm knip` command developers can run without the full quality gate.
+
+**Independent Test**: Run `pnpm knip` from the workspace root and verify it analyzes all three workspace packages and reports results.
+
+### Implementation for User Story 2
+
+- [x] T008 [US2] Add a `"knip": "knip"` script to `package.json` so developers can run `pnpm knip` independently
+- [x] T009 [US2] Verify `pnpm knip` runs from the workspace root and reports results covering all workspace packages (`packages/domain`, `packages/application`, `apps/web`) (SC-003, SC-004)
+
+**Checkpoint**: Developers can run `pnpm knip` standalone. US2 acceptance scenarios 1–2 are satisfied.
+
+---
+
+## Phase 5: Polish & Cross-Cutting Concerns
+
+**Purpose**: Final validation and documentation
+
+- [x] T010 Run quickstart.md validation: confirm `pnpm knip` and `pnpm check` both work as documented
+- [x] T011 Update CLAUDE.md commands section if `pnpm knip` should be listed as a project command
+
+---
+
+## Dependencies & Execution Order
+
+### Phase Dependencies
+
+- **Setup (Phase 1)**: No dependencies — start immediately
+- **Foundational (Phase 2)**: Depends on Phase 1 (T001, T002 must complete first)
+- **User Story 1 (Phase 3)**: Depends on Phase 2 (clean Knip pass required before wiring into gate)
+- **User Story 2 (Phase 4)**: Depends on Phase 3 (T008 modifies the same `package.json` as T005, so must follow it)
+- **Polish (Phase 5)**: Depends on Phases 3 and 4
+
+### User Story Dependencies
+
+- **User Story 1 (P1)**: Depends on Foundational phase — needs clean codebase pass before gate integration
+- **User Story 2 (P2)**: Depends on US1 — T008 modifies the same `package.json` as T005, so must execute after it
+
+### Parallel Opportunities
+
+- T001 and T002 are sequential (T002 needs Knip installed for schema validation)
+- T008 (US2) modifies `package.json` (same as T005), so execute sequentially after T005
+
+---
+
+## Implementation Strategy
+
+### MVP First (User Story 1 Only)
+
+1. Complete Phase 1: Install Knip, create config
+2. Complete Phase 2: Ensure clean pass on current codebase
+3. Complete Phase 3: Wire into quality gate
+4. **STOP and VALIDATE**: `pnpm check` passes clean; intentional unused code is caught
+
+### Incremental Delivery
+
+1. Phase 1 + Phase 2 → Knip works locally
+2. Add US1 (Phase 3) → Quality gate enforced on every commit (MVP!)
+3. Add US2 (Phase 4) → Standalone `pnpm knip` command available
+4. Phase 5 → Documentation updated
+
+---
+
+## Notes
+
+- All tasks modify root-level files only (no domain/application/adapter changes)
+- The Lefthook pre-commit hook already runs `pnpm check`, so no Lefthook config changes needed
+- If Knip reports false positives in Phase 2, the most common fixes are `ignoreDependencies` for tooling packages and `entry` patterns for non-standard entry points