# INTEGRATIONS — document-scanner

_Last updated: 2026-05-21_

## Summary

The backend integrates with four interchangeable AI providers for document classification: Anthropic Claude, OpenAI (and any OpenAI-compatible endpoint), Ollama, and LM Studio. There are no external databases, auth services, or cloud storage integrations — all persistence is local filesystem. The active provider is selected at runtime via settings persisted in `backend/data/settings.json`.

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## AI Providers

All providers implement the `AIProvider` abstract interface defined in `backend/ai/base.py`. The active provider is resolved at request time in `backend/ai/__init__.py:get_provider()`.

### Anthropic

- **SDK:** `anthropic>=0.26` — `backend/ai/anthropic_provider.py`
- **Client:** `anthropic.AsyncAnthropic`
- **API:** Messages API (`client.messages.create`)
- **Default model:** `claude-sonnet-4-6`
- **Auth:** `api_key` stored in `backend/data/settings.json` under `providers.anthropic.api_key`; optionally seeded from env var `ANTHROPIC_API_KEY` (`.env.example`)
- **Calls made:** `classify` (max_tokens=1024), `suggest_topics` (max_tokens=256), `health_check` (max_tokens=5)
- **Text limit:** 8,000 characters per request (`MAX_AI_CHARS = 8_000`)

### OpenAI

- **SDK:** `openai>=1.30` — `backend/ai/openai_provider.py`
- **Client:** `openai.AsyncOpenAI`
- **API:** Chat Completions (`client.chat.completions.create`)
- **Default model:** `gpt-4o`
- **Auth:** `api_key` stored in `backend/data/settings.json` under `providers.openai.api_key`; optionally seeded from env var `OPENAI_API_KEY` (`.env.example`)
- **Custom base URL:** Supported via `providers.openai.base_url` in settings (allows pointing at any OpenAI-compatible endpoint)

### Ollama

- **Provider file:** `backend/ai/ollama_provider.py`
- **Implementation:** Subclass of `OpenAIProvider` — uses the OpenAI SDK with a custom `base_url`
- **Default base URL:** `http://host.docker.internal:11434/v1`
- **Default model:** `llama3.2`
- **Auth:** Stub key `"ollama"` (no real auth required)
- **Network path:** Reaches the host machine's Ollama daemon via Docker's `host.docker.internal` DNS alias (configured in `docker-compose.yml` via `extra_hosts`)

### LM Studio

- **Provider file:** `backend/ai/lmstudio_provider.py`
- **Implementation:** Subclass of `OpenAIProvider` — uses the OpenAI SDK with a custom `base_url`
- **Default base URL:** `http://host.docker.internal:1234/v1`
- **Default model:** `gemma-4-e4b-it`
- **Auth:** Stub key `"lm-studio"` (no real auth required)
- **Network path:** Reaches the host machine's LM Studio server via `host.docker.internal` (same `extra_hosts` setting)
- **Default active provider** — the app works out of the box with LM Studio and no API keys

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## Provider Selection & Settings Persistence

- Active provider and all per-provider config (model names, API keys, base URLs) are persisted in `backend/data/settings.json`.
- Settings are loaded fresh on each classification request in `backend/services/classifier.py:classify_document()`.
- API keys returned from the settings API are masked (last 4 chars shown) via `backend/services/storage.py:mask_api_key()`.
- The Settings UI allows switching providers without restart.

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## Frontend ↔ Backend Communication

- **Protocol:** HTTP REST over JSON (and multipart form for uploads)
- **Client:** Native browser `fetch` API — `frontend/src/api/client.js`
- **Base path:** All requests go to `/api/*` — no hardcoded backend hostname in the frontend
- **Proxy (dev):** Vite dev server proxies `/api` → `http://backend:8000` — `frontend/vite.config.js`
- **Proxy (prod):** Comment in `frontend/src/api/client.js` notes nginx is expected; no nginx config is present in the repo

### API Endpoints consumed by the frontend

| Method | Path | Purpose |
|---|---|---|
| POST | `/api/documents/upload` | Upload file with optional auto-classify flag |
| GET | `/api/documents` | List documents (paginated, optional topic filter) |
| GET | `/api/documents/:id` | Get single document metadata |
| DELETE | `/api/documents/:id` | Delete document |
| POST | `/api/documents/:id/classify` | (Re)classify document, optional topic list |
| GET | `/api/topics` | List all topics |
| POST | `/api/topics` | Create topic |
| PATCH | `/api/topics/:id` | Update topic |
| DELETE | `/api/topics/:id` | Delete topic |
| POST | `/api/topics/suggest` | AI topic suggestions for a document |
| GET | `/api/settings` | Get settings (keys masked) |
| PATCH | `/api/settings` | Update settings |
| POST | `/api/settings/test-provider` | Health-check the active or named provider |
| GET | `/api/settings/default-prompt` | Retrieve the default classification system prompt |

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## Docker Services

Defined in `docker-compose.yml`:

| Service | Image | Port | Notes |
|---|---|---|---|
| `backend` | Built from `./backend/Dockerfile` | `8000:8000` | Mounts `./backend/data:/app/data` for persistence; `./backend:/app` for hot-reload |
| `frontend` | Built from `./frontend/Dockerfile` | `5173:5173` | Mounts `./frontend/src` and `index.html` for hot-reload; depends on `backend` |

Both services use `extra_hosts: host.docker.internal:host-gateway` on the backend to allow Ollama/LM Studio connections to the host machine.

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## Environment Variables

| Variable | Required | Where used | Notes |
|---|---|---|---|
| `DATA_DIR` | No | `backend/config.py` | Root path for uploads/metadata/settings; defaults to `/app/data` |
| `ANTHROPIC_API_KEY` | No | `.env.example` | Bootstrap only — app manages keys via settings UI |
| `OPENAI_API_KEY` | No | `.env.example` | Bootstrap only — app manages keys via settings UI |
| `PYTHONDONTWRITEBYTECODE` | No | `docker-compose.yml` | Set to `1` to suppress `.pyc` files in Docker |

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## Authentication & Identity

- No user authentication. The application has no login system, sessions, or identity provider.
- API keys for AI providers are stored in plain text in `backend/data/settings.json` (masked only when returned via the settings API).

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## Monitoring & Observability

- No error tracking service (no Sentry, Datadog, etc.).
- No structured logging framework — FastAPI default stdout logging only.
- A `/health` endpoint exists at `backend/main.py` returning `{"status": "ok"}`.
- Provider connectivity tested on demand via `POST /api/settings/test-provider`.

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## Webhooks & Callbacks

- None — the application makes no outbound webhook calls and exposes no webhook receiver endpoints.

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## Gaps / Unknowns

- No nginx or reverse-proxy config present for production deployments; the client-side comment references it but no config exists.
- No container registry or CI/CD pipeline configuration detected.
- API keys are stored in a plain JSON file on disk with no encryption at rest.
- The `ANTHROPIC_API_KEY` / `OPENAI_API_KEY` env vars from `.env.example` are noted as bootstrap helpers but no code in the repo reads them directly — they appear to be manual seeding hints only.