# Cross-Artifact Consistency Analysis

**Feature**: `002-youtube-design-preview`
**Analyzed**: 2026-01-29
**Artifacts**: spec.md, plan.md, research.md, data-model.md, contracts/types.ts, tasks.md

---

## Executive Summary

| Metric | Value |
|--------|-------|
| Total Requirements (FR) | 20 |
| Total User Stories | 4 |
| Total Tasks | 50 |
| Requirements Covered | 20/20 (100%) |
| Constitution Alignment | PASS |
| Critical Issues | 0 |
| Warnings | 3 |
| Suggestions | 4 |

**Overall Status**: Ready for implementation

---

## Findings

| ID | Category | Severity | Location | Summary | Recommendation |
|----|----------|----------|----------|---------|----------------|
| A-001 | Underspecification | Warning | spec.md:FR-017 | Weekly screenshot capture mechanism not detailed | Add cron/scheduler details to plan.md or tasks.md |
| A-002 | Inconsistency | Warning | tasks.md:T041 | Script path uses `.ts` but may need to be executable | Verify ts-node setup or use compiled JS for scheduler |
| A-003 | Coverage Gap | Warning | tasks.md | FR-009 (responsive breakpoints) only partially addressed by T043 | Consider adding explicit breakpoint tests |
| A-004 | Suggestion | Info | data-model.md | `publishedAt` stored as Date but templates show "X days ago" | Add utility function for relative time formatting |
| A-005 | Suggestion | Info | contracts/types.ts | `VALIDATION_CONSTANTS.DURATION_REGEX` allows single-digit minutes | Consider stricter format `^\d{1,3}:\d{2}$` for edge cases |
| A-006 | Suggestion | Info | research.md | Sidebar dimensions (168x94) have different ratio than 16:9 | Document this intentional deviation from standard 16:9 |
| A-007 | Suggestion | Info | tasks.md | T017 hover states may conflict with mobile (no hover on touch) | Add note to disable hover states in mobile variant |

---

## Requirement Coverage Matrix

| Requirement | User Story | Tasks | Status |
|-------------|------------|-------|--------|
| FR-001 (Desktop pixel-perfect) | US1 | T012-T020 | Covered |
| FR-002 (Mobile pixel-perfect) | US2 | T021-T026 | Covered |
| FR-003 (Sidebar pixel-perfect) | US3 | T027-T033 | Covered |
| FR-004 (Real-time upload) | US1-3 | T010-T011 | Covered |
| FR-005 (Metadata elements) | US1-3 | T012-T016, T020-T032 | Covered |
| FR-006 (Typography) | US1-3 | T013-T014, T023, T029 | Covered |
| FR-007 (Spacing/padding) | US1-3 | T018, T024, T031 | Covered |
| FR-008 (Hover states) | US1 | T017 | Covered |
| FR-009 (Responsive breakpoints) | - | T043 | Partial |
| FR-010 (Playwright integration) | US4 | T034-T042 | Covered |
| FR-011 (Visual diff reports) | US4 | T035 | Covered |
| FR-012 (Customizable metadata) | US1 | T020 | Covered |
| FR-013 (Duration badge) | US1-3 | T016 | Covered |
| FR-014 (Channel avatar) | US1-2 | T015, T022, T032 | Covered |
| FR-015 (Local storage) | - | T004, T006-T007, T047 | Covered |
| FR-016 (Theme toggle) | - | T008, T019 | Covered |
| FR-017 (Weekly capture) | US4 | T041 | Covered |
| FR-018 (Historical screenshots) | US4 | T036 | Covered |
| FR-019 (5MB limit) | - | T010-T011 | Covered |
| FR-020 (Image formats) | - | T010-T011 | Covered |

---

## Constitution Alignment Check

| Principle | Status | Notes |
|-----------|--------|-------|
| I. Tech Stack | PASS | React 19.x, TS 5.x, Tailwind 4.x, shadcn/ui, Zustand - all aligned |
| II. Architecture | PASS | Feature code in `frontend/src/`, correct directory structure |
| III. Styling | PASS | YouTube CSS variables defined, Tailwind utilities used |
| IV. Data Management | PASS | Zustand for state, localStorage for persistence |
| V. Development Practices | PASS | TypeScript strict, ESLint, explicit types in contracts |

**No constitution violations detected.**

---

## Duplication Analysis

| Area | Finding |
|------|---------|
| Type Definitions | `contracts/types.ts` and `data-model.md` contain same interfaces - **Acceptable** (one is documentation, one is code) |
| CSS Values | `research.md` and `quickstart.md` both list CSS values - **Minor overlap**, quickstart is intentional quick reference |
| Default Values | `data-model.md` and `contracts/types.ts` both define defaults - **Need to keep in sync** |

**Recommendation**: Consider generating `data-model.md` from `contracts/types.ts` to prevent drift.

---

## Ambiguity Detection

| Location | Ambiguity | Resolution |
|----------|-----------|------------|
| spec.md:FR-017 | "Automated weekly capture" - when exactly? | Suggest: Sunday 00:00 UTC, document in tasks.md |
| spec.md:SC-004 | "90% of users" - how to measure in blind test? | This is a qualitative metric, may be hard to automate |
| tasks.md:T036 | "Copy reference screenshots" - from where? | From `specs/002-youtube-design-preview/reference/` (clarified in research.md) |

---

## Task Dependency Analysis

### Critical Path

```
Phase 1 (Setup)     → Phase 2 (Foundational) → Phase 3-6 (User Stories) → Phase 7 (Polish)
T001-T005 [parallel]   T006-T011 [sequential]    US1-US4 [parallel]         T043-T050 [parallel]
```

### Blocking Dependencies

| Task | Blocked By | Blocks |
|------|------------|--------|
| T006-T011 | T001-T005 | T012-T050 (all user stories) |
| T037-T040 | T034-T036 | None (test tasks) |
| T049 (lint) | All implementation | T050 (validation) |

### Parallel Opportunities

- **Phase 1**: T001, T002, T003, T004 can all run in parallel
- **Phase 2**: T008, T009 can run in parallel after T006-T007
- **Phase 3-5**: US1, US2, US3 can be implemented in parallel by different developers
- **Phase 6**: T034, T035, T036 can run in parallel (test setup)
- **Phase 7**: T043, T044, T045, T046, T047 can all run in parallel

---

## Risk Assessment

| Risk | Likelihood | Impact | Mitigation |
|------|------------|--------|------------|
| YouTube design changes during development | Medium | High | Reference screenshots versioned, weekly updates |
| Visual test flakiness | Medium | Medium | 98% threshold allows minor variance |
| localStorage quota exceeded | Low | Medium | T047 adds 10-thumbnail limit |
| Playwright MCP unavailable | Low | High | Manual screenshot capture as fallback |

---

## Recommendations

### High Priority

1. **Clarify weekly capture schedule**: Add specific timing (e.g., "Sundays at 00:00 UTC") to avoid ambiguity
2. **Add responsive test coverage**: T043 covers responsive breakpoints but no visual tests for intermediate sizes

### Medium Priority

3. **Consider relative time utility**: Add `formatRelativeTime(date: Date): string` to lib functions
4. **Document sidebar ratio**: Note in research.md that sidebar uses slightly different aspect ratio

### Low Priority

5. **Sync default values**: Ensure `data-model.md` defaults match `contracts/types.ts`
6. **Mobile hover handling**: Explicitly disable hover states for mobile variant to avoid touch UX issues

---

## Next Actions

1. Address Warning items (A-001, A-002, A-003) before implementation begins
2. Proceed with Phase 1 (Setup) - all tasks can run in parallel
3. After Phase 2 completion, checkpoint to verify foundation before user stories
4. Consider running US1-US3 in parallel if multiple developers available

---

**Analysis complete. Feature is ready for implementation with minor clarifications recommended.**