# KNOW-003: Tag Management API - Completion Summary

## Status: ✅ Complete

### Implemented Files

#### DTOs (Data Transfer Objects)

- **`apps/api/src/knowledge/dto/create-tag.dto.ts`**
  - Validates tag creation input
  - Required: `name`
  - Optional: `slug`, `color` (hex format), `description`
  - Slug validation: lowercase alphanumeric with hyphens

- **`apps/api/src/knowledge/dto/update-tag.dto.ts`**
  - Validates tag update input
  - All fields optional for partial updates
  - Same validation rules as create DTO

#### Service Layer

- **`apps/api/src/knowledge/tags.service.ts`**
  - `create()` - Creates tag with auto-generated slug if not provided
  - `findAll()` - Lists all workspace tags with entry counts
  - `findOne()` - Gets single tag by slug
  - `update()` - Updates tag, regenerates slug if name changes
  - `remove()` - Deletes tag (cascade removes entry associations)
  - `getEntriesWithTag()` - Lists all entries tagged with specific tag
  - `findOrCreateTags()` - Helper for entry creation/update with auto-create option

#### Controller Layer

- **`apps/api/src/knowledge/tags.controller.ts`**
  - All endpoints authenticated via `AuthGuard`
  - Workspace isolation enforced on all operations
  - Endpoints:
    - `POST /api/knowledge/tags` - Create tag
    - `GET /api/knowledge/tags` - List tags
    - `GET /api/knowledge/tags/:slug` - Get tag
    - `PUT /api/knowledge/tags/:slug` - Update tag
    - `DELETE /api/knowledge/tags/:slug` - Delete tag (204 No Content)
    - `GET /api/knowledge/tags/:slug/entries` - Get entries with tag

#### Module Configuration

- **`apps/api/src/knowledge/knowledge.module.ts`**
  - Imports: PrismaModule, AuthModule
  - Exports: TagsService (for use by entry service)

- **Updated `apps/api/src/app.module.ts`**
  - Added KnowledgeModule to main app imports

#### Tests

- **`apps/api/src/knowledge/tags.service.spec.ts`** (17 tests, all passing)
  - Tests for all CRUD operations
  - Slug generation and validation
  - Conflict detection
  - Entry associations
  - Auto-create functionality

- **`apps/api/src/knowledge/tags.controller.spec.ts`** (12 tests, all passing)
  - Tests for all endpoints
  - Authentication validation
  - Request/response handling

### Key Features

1. **Automatic Slug Generation**
   - Converts tag names to URL-friendly slugs
   - Example: "My Tag Name!" → "my-tag-name"
   - Can be overridden with custom slug

2. **Workspace Isolation**
   - All operations scoped to user's workspace
   - Tags are unique per workspace (slug-based)

3. **Color Validation**
   - Hex color format required (#RRGGBB)
   - Optional field for UI customization

4. **Entry Count**
   - Tag list includes count of associated entries
   - Useful for UI display and tag management

5. **Auto-Create Support**
   - `findOrCreateTags()` method for entry service
   - Enables creating tags on-the-fly during entry creation
   - Generates friendly names from slugs

6. **Conflict Handling**
   - Detects duplicate slugs within workspace
   - Returns 409 Conflict with descriptive message
   - Handles race conditions during auto-create

### Test Coverage

- **Total Tests**: 29 passing
- **Service Tests**: 17
- **Controller Tests**: 12
- **Coverage Areas**:
  - CRUD operations
  - Validation (slug format, color format)
  - Error handling (not found, conflicts, bad requests)
  - Workspace isolation
  - Auto-create functionality
  - Authentication checks

### TypeScript Compliance

- ✅ No `any` types used
- ✅ Explicit return types on all public methods
- ✅ Explicit parameter types throughout
- ✅ Interfaces used for DTOs
- ✅ Proper error handling with typed exceptions
- ✅ Follows `~/.claude/agent-guides/typescript.md`
- ✅ Follows `~/.claude/agent-guides/backend.md`

### Database Schema

Uses existing Prisma schema:

```prisma
model KnowledgeTag {
  id          String    @id @default(uuid()) @db.Uuid
  workspaceId String    @map("workspace_id") @db.Uuid
  workspace   Workspace @relation(...)

  name        String
  slug        String
  color       String?
  description String?

  entries     KnowledgeEntryTag[]

  @@unique([workspaceId, slug])
  @@index([workspaceId])
}
```

### Integration Points

1. **Entry Service** (parallel implementation)
   - Will use `TagsService.findOrCreateTags()` for tag associations
   - Entry create/update accepts tag slugs array
   - Auto-create option available

2. **Authentication**
   - Uses existing `AuthGuard` from `apps/api/src/auth/guards/auth.guard.ts`
   - Workspace ID extracted from request user context

3. **Prisma**
   - Uses existing `PrismaService` for database operations
   - Leverages Prisma's type-safe query builder

### Next Steps (for Entry Service Integration)

1. Update entry service to accept `tags: string[]` in DTOs
2. Call `TagsService.findOrCreateTags()` during entry creation/update
3. Associate tags via `KnowledgeEntryTag` junction table
4. Consider adding `autoCreateTags: boolean` option to entry DTOs

### Git Commit

```
feat(knowledge): add tag management API (KNOW-003)

- Add Tag DTOs (CreateTagDto, UpdateTagDto) with validation
- Implement TagsService with CRUD operations
- Add TagsController with authenticated endpoints
- Support automatic slug generation from tag names
- Add workspace isolation for tags
- Include entry count in tag responses
- Add findOrCreateTags method for entry creation/update
- Implement comprehensive test coverage (29 tests passing)

Endpoints:
- GET /api/knowledge/tags - List workspace tags
- POST /api/knowledge/tags - Create tag
- GET /api/knowledge/tags/:slug - Get tag by slug
- PUT /api/knowledge/tags/:slug - Update tag
- DELETE /api/knowledge/tags/:slug - Delete tag
- GET /api/knowledge/tags/:slug/entries - List entries with tag

Related: KNOW-003
```

Commit hash: `f07f044`

---

**Task Status**: COMPLETE ✅
**Coding Standards**: Compliant ✅
**Tests**: Passing (29/29) ✅
**Documentation**: Updated ✅
