# Phase 4 Backend Deliverables - Complete

**Delivered by:** Socrates 🧠  
**Date:** 2026-04-21  
**Status:** ✅ Complete

---

## Deliverables Summary

### 1. Search Endpoint (FTS5) ✅

**Endpoint:** `GET /api/blog/search?q={query}`

**Features:**
- Full-text search using SQLite FTS5 virtual table
- Searches across title, excerpt, and content
- Results ranked by relevance (using BM25 ranking algorithm)
- Configurable limit parameter (default 20, max 50)
- Only searches published posts
- Proper FTS5 query escaping (handles special characters like hyphens)

**Implementation:**
- `service.py`: `search_posts()` function
- `storage.py`: FTS5 virtual table with sync triggers
- `router.py`: `/search` endpoint with query parameter validation
- `models.py`: `SearchResponse` and `SearchResult` models

---

### 2. Related Posts Algorithm ✅

**Endpoint:** `GET /api/blog/posts/{slug}/related?limit={n}`

**Algorithm:**
- Posts in the same category score **+2 points**
- Each shared tag scores **+1 point**
- Results sorted by score (descending), then by publication date (descending)
- Returns only published posts
- Excludes the source post
- Respects the limit parameter (default 3, max 10)

**Implementation:**
- `service.py`: `get_related_posts()` function
- Uses efficient SQL with GROUP_CONCAT for tag matching
- Returns `PostListResponse` for consistent API response format

---

## Files Created/Modified

### Core Module Files

| File | Description |
|------|-------------|
| `__init__.py` | Module initialization, exports `blog_router` |
| `models.py` | Pydantic models for requests/responses including SearchResponse |
| `storage.py` | SQLite + Markdown I/O, FTS5 schema, sync triggers |
| `service.py` | Business logic: search, related posts, CRUD operations |
| `router.py` | FastAPI routes including `/search` and `/{slug}/related` |

### Tests

| File | Description |
|------|-------------|
| `test_phase4.py` | 15 unit tests covering search and related posts |
| `test_integration.py` | Integration tests for API endpoints |

### Supporting Files

| File | Description |
|------|-------------|
| `requirements.txt` | Dependencies (FastAPI, Pydantic, Markdown, PyYAML, pytest) |
| `main.py` | FastAPI application entry point |
| `PHASE4_DELIVERABLES.md` | This document |

---

## API Endpoints Summary

### Public Endpoints

```
GET  /api/blog/posts              # List posts (paginated, filterable)
GET  /api/blog/posts/{slug}        # Get single post
GET  /api/blog/posts/{slug}/related # Get related posts (NEW ✅)
GET  /api/blog/categories          # List categories
GET  /api/blog/tags               # List tags
GET  /api/blog/search?q={query}   # Full-text search (NEW ✅)
```

### Admin Endpoints (already working, confirmed)

```
GET    /api/blog/admin/posts                    # List all posts (with status filter)
POST   /api/blog/admin/posts                    # Create new post
GET    /api/blog/admin/posts/{slug}             # Get post (any status)
PATCH  /api/blog/admin/posts/{slug}             # Update post
DELETE /api/blog/admin/posts/{slug}            # Archive post
POST   /api/blog/admin/posts/{slug}/publish     # Publish draft
POST   /api/blog/admin/posts/{slug}/unpublish   # Unpublish to draft
POST   /api/blog/admin/posts/{slug}/preview     # Preview Markdown → HTML
POST   /api/blog/admin/posts/{slug}/regenerate  # Regenerate static HTML
POST   /api/blog/admin/rebuild                 # Full rebuild
```

---

## Test Results

```
Phase 4 Unit Tests: 15/15 passed
- TestSearch: 5/5 passed
- TestRelatedPosts: 7/7 passed  
- TestSlugGeneration: 3/3 passed

Integration Tests: 6/6 passed
- Health check
- Root endpoint
- Empty posts listing
- Empty search
- Empty categories
- Empty tags
```

---

## Database Schema (FTS5)

```sql
-- Full-text search virtual table
CREATE VIRTUAL TABLE posts_fts USING fts5(
    title,
    excerpt,
    content,
    content='posts',
    content_rowid='id'
);

-- Sync triggers keep FTS index in sync with posts table
CREATE TRIGGER posts_fts_insert AFTER INSERT ON posts ...
CREATE TRIGGER posts_fts_delete AFTER DELETE ON posts ...
CREATE TRIGGER posts_fts_update AFTER UPDATE ON posts ...
```

---

## Related Posts Scoring

```python
# Algorithm implemented in service.py:get_related_posts()
score = 0
if post.category == source.category:
    score += 2  # Same category bonus

shared_tags = post.tags & source.tags
score += len(shared_tags)  # +1 per shared tag
```

---

## Next Steps

The Phase 4 backend deliverables are complete. Daedalus can now:

1. Wire the `/search` endpoint into the blog UI search box
2. Display related posts on individual article pages
3. Continue building admin UI templates (already has working API endpoints)

---

_Ready for integration testing with Daedalus' frontend work._