# Final Implementation Report — Distributed Architecture

**Date**: 2026-03-31
**Epic**: AZ-172 (Distributed Architecture Adaptation)
**Tasks**: 4 implemented, 0 blocked

## Summary

All 4 tasks from the distributed architecture epic have been successfully implemented across 3 batches. The detection service now operates in a distributed architecture where media is received as byte streams rather than local file paths, AI configuration is fetched from the database via the annotations service, and media records are managed with proper status lifecycle tracking.

## Batch Summary

| Batch | Tasks | Complexity | Verdict | Commit |
|-------|-------|-----------|---------|--------|
| 1 (sequential) | AZ-173, AZ-174 | 5 pts | PASS_WITH_WARNINGS | 6c24d09 |
| 2 | AZ-175 | 2 pts | PASS_WITH_WARNINGS | 40be55a |
| 3 | AZ-176 | 1 pt | PASS | 9411103 |

**Total**: 8 complexity points, 3 batches, 0 blockers

## Key Changes

### AZ-173: Stream-Based Detection API
- New `run_detect_video` and `run_detect_image` methods accept bytes instead of file paths
- PyAV library for video stream decoding from memory buffers
- Simultaneous disk write and frame processing via background thread
- Image decoding via `cv2.imdecode` from bytes buffer

### AZ-174: DB-Driven AI Configuration
- `AIRecognitionConfig.paths` field removed
- Configuration fetched from annotations service `GET /api/users/{userId}/ai-settings`
- JWT userId extraction via `TokenManager.decode_user_id`
- Multi-format field name mapping (snake_case, camelCase, PascalCase)
- Fallback to sensible defaults if service unreachable

### AZ-175: Media Table Integration
- XxHash64 content hashing with sampling algorithm
- Media record creation via annotations service `POST /api/media`
- Persistent file storage at configurable directories
- MediaStatus lifecycle: New(1) → AIProcessing(2) → AIProcessed(3) / Error(6)

### AZ-176: Cleanup Obsolete Path-Based Code
- Removed `is_video`, `run_detect`, `_process_video` (cv2.VideoCapture), `_process_images` (cv2.imread)
- Cleaned up dead imports (mimetypes, pathlib.Path)

## Test Results

- Unit tests: 14/14 passed
- New dependencies: `av==14.2.0`, `xxhash==3.5.0`

## Files Modified

| File | Changes |
|------|---------|
| `src/inference.pyx` | Stream-based methods, removed path-based methods |
| `src/main.py` | Media lifecycle, DB config, upload handling |
| `src/ai_config.pxd` | Removed `paths` field |
| `src/ai_config.pyx` | Removed `paths` from init/from_dict |
| `src/loader_http_client.pyx` | `fetch_user_ai_settings`, `fetch_media_path` |
| `src/loader_http_client.pxd` | Method declarations |
| `src/media_hash.py` | New — XxHash64 content hashing |
| `requirements.txt` | Added `av`, `xxhash` |
| `e2e/mocks/annotations/app.py` | New mock endpoints |
| `e2e/tests/test_async_sse.py` | Adapted for new API |
| `e2e/tests/test_video.py` | Adapted for new API |