┌─────────────────────────────────────────────────────────────┐
│   ┌──────────┐    ┌──────────┐    ┌──────────┐             │
│   │  UI 层   │───▶│ 前端服务 │───▶│ 前端 API │              │
│   │(Vue3)    │    │(Pinia)   │    │(Axios)   │              │
│   └──────────┘    └──────────┘    └────┬─────┘             │
│                              HTTP Request                   │
│                                        ▼                    │
│   ┌──────────┐    ┌──────────┐    ┌──────────┐             │
│   │ 数据层   │◀───│ 后端服务 │◀───│ 后端 API │              │
│   │(SQLAlch) │    │(Service) │    │(FastAPI) │              │
│   └──────────┘    └──────────┘    └──────────┘             │
└─────────────────────────────────────────────────────────────┘

## Modification Plan: [Feature Name]

### Modification Entry
- **Entry Layer**: [Layer Name]
- **Modification Reason**: [Original User Requirement]

### Layer-by-layer Modification Details
#### 1. [Layer 1] Modification
**Change Content**: [Specific Modification Points]
**Code Changes**: [Code Snippets]

### Cross-layer Consistency Check
- [ ] Field name consistency
- [ ] Type matching
- [ ] Interface contract

### Database Migration (if needed)
```bash
alembic revision --autogenerate -m "description"

## Resource Index

| Resource | Path | Purpose |
|----------|------|---------|
| Cross-layer Modification Workflow | [references/cross_layer_workflow.md](references/cross_layer_workflow.md) | Detailed cross-layer modification workflow and examples |
| Architecture Layer Description | [references/architecture_layers.md](references/architecture_layers.md) | Detailed responsibilities and constraints of six-layer architecture |
| Code Patterns | [references/code_patterns.md](references/code_patterns.md) | Common code patterns, type synchronization |
| Security Checklist | [references/security_checklist.md](references/security_checklist.md) | Security review key points |
| Code Templates | [assets/templates/](assets/templates/) | Code template files for each layer |

## Notes

- **Identifying the entry layer is crucial**: Accurately determining which layer the user initiates modification from determines the deduction direction
- **Bidirectional deduction**: Modifications in middle layers require both forward and backward impact deduction
- **Maintain consistency**: Field naming, type definitions, and interface contracts must remain consistent across all layers
- **Database migration**: Data layer changes must generate Alembic migration scripts
- **Make full use of agent capabilities**: Let the agent automatically deduce cross-layer impacts to avoid omissions

## Usage Examples

### Example 1: Modification Initiated from UI Layer

**User Requirement**: "User detail page needs to display registration time"

**Entry Layer Identification**: UI Layer (keyword "page display")

**Deduction Process**: UI layer needs to display → requires Store to provide → requires API to return → backend needs to query → database needs the field

**Modification Plan**:
1. **Data Layer**: Add `registration_time` field to users table
2. **Backend Service Layer**: Add field to User model
3. **Backend API Layer**: Add `registration_time` field to UserResponse
4. **Frontend API Layer**: Add field to TypeScript User interface
5. **Frontend Service Layer**: Add `registrationTime` state to userStore
6. **UI Layer**: Add registration time display to UserProfile component

### Example 2: Modification Initiated from Data Layer

**User Requirement**: "User table needs to add a phone number field for SMS notifications"

**Entry Layer Identification**: Data Layer (keyword "table add field")

**Deduction Process**: Database has the field → backend can access and store → API can transmit → frontend can call → Store can manage → UI can input/display

**Modification Plan**:
1. **Data Layer**: Add `phone_number` field to users table
2. **Backend Service Layer**: Add phone number verification logic to UserService
3. **Backend API Layer**: Add phone number parameter validation
4. **Frontend API Layer**: Update User interface
5. **Frontend Service Layer**: Add phone number state to userStore
6. **UI Layer**: Add phone number input box to user profile edit page

### Example 3: Modification Initiated from Middle Layer

**User Requirement**: "Backend API needs to add order filtering by status"

**Entry Layer Identification**: Backend API Layer (keyword "API add")

**Deduction Process**:
- Backward: API parameters → Service layer filtering logic → Database query conditions
- Forward: API parameters ← Frontend call ← Store method ← UI component

**Modification Plan**:
1. **Backend API Layer**: Add `status` query parameter to `GET /orders`
2. **Backend Service Layer**: Add status-based filtering logic to OrderService
3. **Data Layer**: Ensure orders table has index for `status` field
4. **Frontend API Layer**: Add `status` parameter to `getOrders()`
5. **Frontend Service Layer**: Add filter status to orderStore
6. **UI Layer**: Add status filter dropdown to order list page