# Bookshelf — Technical Overview

## Purpose
Photo-based book cataloger. Hierarchy: Room → Cabinet → Shelf → Book.
AI plugins identify spine text; archive plugins supply bibliographic metadata.

## Stack
- **Server**: FastAPI + SQLite (no ORM), Python 3.11+, Poetry (`poetry run serve`)
- **Frontend**: Vanilla JS SPA — `static/index.html` + `static/css/` + `static/js/`; no build step
- **AI**: OpenAI-compatible API (OpenRouter, OpenAI, etc.) via `openai` library
- **Images**: Stored uncompressed in `data/images/`; Pillow used server-side for crops and AI prep

## Directory Layout
```
src/
  app.py                        # FastAPI app, exception handlers
  api.py                        # All routes (APIRouter)
  db.py                         # All SQL; connection() / transaction() context managers
  files.py                      # Image file I/O; DATA_DIR, IMAGES_DIR
  config.py                     # Config loading and typed AppConfig
  models.py                     # Typed dataclasses / mashumaro decoders
  errors.py                     # Domain exceptions (NotFoundError, BadRequestError subtypes)
  logic/
    __init__.py                 # dispatch_plugin() orchestrator + re-exports
    boundaries.py               # Boundary math, shelf/spine crop sources, boundary detector runner
    identification.py           # Status computation, text recognizer, book identifier runners
    archive.py                  # Archive searcher runner (sync + background)
    batch.py                    # Batch pipeline, process_book_sync
    images.py                   # crop_save, prep_img_b64, serve_crop
  plugins/
    __init__.py                 # Registry: load_plugins(), get_plugin(), get_manifest()
    rate_limiter.py             # Thread-safe per-domain rate limiter
    ai_compat/                  # AI plugin implementations
    archives/                   # Archive plugin implementations
scripts/
  presubmit.py                  # Poetry console entry points: fmt, presubmit
static/
  index.html                    # HTML shell + CSS/JS imports (load order matters)
  css/                          # base, layout, tree, forms, overlays
  js/                           # state → helpers → api → canvas-boundary → tree-render →
                                #   detail-render → canvas-crop → editing → photo → events → init
config/
  credentials.default.yaml      # API endpoints and keys (override in credentials.user.yaml)
  models.default.yaml           # Model selection and prompts per AI function
  functions.default.yaml        # Plugin definitions and per-plugin settings
  ui.default.yaml               # UI display settings
  *.user.yaml                   # Gitignored overrides — create these with real values
data/                           # Runtime: books.db + images/ (gitignored)
tests/
  *.py                          # Python tests (pytest)
  js/pure-functions.test.js     # JS tests (node:test)
docs/
  overview.md                   # This file
  contributing.md               # Documentation and contribution standards
```

## Layer Architecture
Unidirectional: `api` → `logic` → `db` / `files`. No layer may import from a layer above it.

- **api**: HTTP parsing, entity existence checks via `db.connection()`, calls logic, returns HTTP responses. Owns HTTPException and status codes.
- **logic**: Business operations, no HTTP/FastAPI imports. Raises domain exceptions from `errors.py` for expected failures.
- **db / files**: SQL and file I/O only. Returns typed dataclasses or None. Never raises domain exceptions.

## Configuration System
Config loaded from `config/*.default.yaml` merged with `config/*.user.yaml`. Deep merge: dicts recursive, lists replaced. Typed via `mashumaro BasicDecoder[AppConfig]`.

Categories:

| File | Purpose |
|------|---------|
| `credentials` | `base_url` + `api_key` per endpoint; no model or prompt |
| `models` | `credentials` ref + `model` string + optional `extra_body` + `prompt` |
| `functions` | Plugin definitions; dict key = plugin_id (unique across all categories) |
| `ui` | Frontend display settings |

Minimal setup — create `config/credentials.user.yaml`:
```yaml
credentials:
  openrouter:
    api_key: "sk-or-your-actual-key"
```

## Plugin System

### Categories
| Category | Input | Output | DB field |
|----------|-------|--------|----------|
| `boundary_detectors` (`target=shelves`) | cabinet image | `{boundaries:[…], confidence:N}` | `cabinets.ai_shelf_boundaries` |
| `boundary_detectors` (`target=books`) | shelf image | `{boundaries:[…]}` | `shelves.ai_book_boundaries` |
| `text_recognizers` | spine image | `{raw_text, title, author, …}` | `books.raw_text` + `candidates` |
| `book_identifiers` | raw_text | `{title, author, …, confidence}` | `books.ai_*` + `candidates` |
| `archive_searchers` | query string | `[{source, title, author, …}, …]` | `books.candidates` |

### Universal plugin endpoint
```
POST /api/{entity_type}/{entity_id}/plugin/{plugin_id}
```
Routes to the correct runner via `dispatch_plugin()` in `logic/__init__.py`.

### AI Plugin Configuration
- `credentials` file: connection only — `base_url`, `api_key`.
- `models` file: `credentials` ref, `model` string, `prompt` text, optional `extra_body`.
- `functions` file: per-plugin settings — `model`, `max_image_px` (default 1600), `confidence_threshold` (default 0.8), `auto_queue`, `rate_limit_seconds`, `timeout`.
- `OUTPUT_FORMAT` is a hardcoded class constant in each plugin — not user-configurable; injected into the prompt as `${OUTPUT_FORMAT}` by `AIClient`.

### Archive plugins
All implement `search(query: str) -> list[CandidateRecord]`. Use shared `RATE_LIMITER` singleton for per-domain throttling.

### Auto-queue
- After `text_recognizer` completes → fires all `archive_searchers` with `auto_queue: true` in background thread pool.
- `POST /api/batch` → runs `text_recognizers` then `archive_searchers` for all unidentified books.

## Database Schema (key fields)
| Table | Notable columns |
|-------|-----------------|
| `cabinets` | `shelf_boundaries` (JSON `[…]`), `ai_shelf_boundaries` (JSON `{pluginId:[…]}`) |
| `shelves` | `book_boundaries`, `ai_book_boundaries` (same format), `photo_filename` (optional override) |
| `books` | `raw_text`, `ai_title/author/year/isbn/publisher`, `candidates` (JSON `[{source,…}]`), `identification_status` |

`identification_status`: `unidentified` → `ai_identified` → `user_approved`.

## Boundary System
N interior boundaries → N+1 segments. `full = [0] + boundaries + [1]`. Segment K spans `full[K]..full[K+1]`.
- User boundaries: `shelf_boundaries` / `book_boundaries` (editable via canvas drag)
- AI suggestions: `ai_shelf_boundaries` / `ai_book_boundaries` (JSON object `{pluginId: [fractions]}`)
- Shelf K image = cabinet photo cropped to `(0, y_start, 1, y_end)` unless shelf has override photo
- Book K spine = shelf image cropped to `(x_start, *, x_end, *)` with composed crop if cabinet-based

## Frontend JS
No ES modules, no bundler. All files use global scope; load order in `index.html` is the dependency order. State lives in `state.js` (`S`, `_plugins`, `_bnd`, `_photoQueue`, etc.). Events delegated via `#app` in `events.js`.

## Tooling
```
poetry run serve       # start uvicorn on :8000
poetry run fmt         # black (in-place)
poetry run presubmit   # black --check + flake8 + pyright + pytest + JS tests
npm install            # install ESLint + Prettier (requires network; enables JS lint/fmt in presubmit)
npm run lint           # ESLint on static/js/
npm run fmt            # Prettier on static/js/
```
Line length: 120. Pyright strict mode. Pytest fixtures with `yield` return `Iterator[T]`.
Test fixtures: monkeypatch `db.DB_PATH` / `files.DATA_DIR` / `files.IMAGES_DIR`.

## Key API Endpoints
```
GET    /api/config                                       # UI config + plugin manifest
GET    /api/tree                                         # full nested tree
POST   /api/{entity_type}/{entity_id}/plugin/{plugin_id} # universal plugin runner
PATCH  /api/cabinets/{id}/boundaries                     # update shelf boundary list
PATCH  /api/shelves/{id}/boundaries                      # update book boundary list
GET    /api/shelves/{id}/image                           # shelf image (override or cabinet crop)
GET    /api/books/{id}/spine                             # book spine crop
POST   /api/books/{id}/process                           # full auto-queue pipeline (single book)
POST   /api/batch / GET /api/batch/status                # batch processing
POST   /api/books/{id}/dismiss-field                     # dismiss a candidate suggestion
PATCH  /api/{kind}/reorder                               # drag-to-reorder
POST   /api/cabinets/{id}/crop / POST /api/shelves/{id}/crop  # permanent crop
```