Technical Plans: Bridging Specification and Implementation

┌────────────────────────────────────────────────────────────────┐
│  📋 PRD → 📝 Specification (WHAT) → 🏗️ Technical Plan (HOW)     │
│                                      ◄── CURRENT LESSON        │
│  → ✅ Task Decomposition → 💻 Implementation        📝          │
└────────────────────────────────────────────────────────────────┘

## Architecture: Task Comments

Component Flow:
Client → API Endpoint → CommentService → CommentRepository → Database

Data Flow:
1. Client sends POST /api/tasks/{id}/comments with JWT
2. API validates token, calls `CommentService.create_comment()`
3. Service validates: user owns task, content length valid
4. Service calls CommentRepository.create()
5. Repository persists via SQLAlchemy, returns Comment
6. API transforms to CommentSchema, returns 201

## Data Model: Comment

Table: comments
- `id`: UUID, primary key, default=uuid4
- `task_id`: UUID, FK to tasks.id, NOT NULL
- `user_id`: UUID, FK to users.id, NOT NULL
- `content`: String(5000), NOT NULL
- `created_at`: DateTime, default=utcnow, NOT NULL

Relationships:
- task: relationship to Task (backref="comments")
- author: relationship to User (backref="comments")

Indexes:
- (`task_id`, `created_at`) for chronological listing