# backend — Claude context

FastAPI async gateway, port 8000 (internal). Handles auth, user/group management, settings, and proxies document/category requests to `doc-service:8001`. See root `CLAUDE.md` for architecture, Docker, and project-wide workflows.

---

## Commands

All commands run inside Docker — never on the host.

### Migrations

```bash
docker compose exec backend alembic revision --autogenerate -m "describe change"
docker compose exec backend alembic upgrade head
docker compose exec backend alembic downgrade -1
```

### Lint

```bash
docker compose exec backend ruff check . && ruff format .
```

---

## File & Folder Tree

```
backend/
├── app/
│   ├── main.py                        ← App factory, router registration, lifespan (health loop)
│   ├── database.py                    ← AsyncEngine, AsyncSessionLocal, Base
│   ├── deps.py                        ← get_current_user, get_current_admin, get_service_admin(id), check_plugin_access (also get_user_groups in doc-service)
│   ├── core/
│   │   ├── config.py                  ← All settings via pydantic-settings (reads .env)
│   │   ├── security.py                ← JWT sign/verify (RS256), bcrypt hash/verify
│   │   ├── sanitize.py                ← Input sanitization helpers (see Security Standards)
│   │   └── app_config.py              ← Per-service config load/save to /config volume; theme files in /config/themes/
│   ├── models/
│   │   ├── __init__.py                ← Imports all models (required for Alembic autogenerate)
│   │   ├── user.py                    ← User model
│   │   ├── profile.py                 ← Profile model
│   │   └── group.py                   ← Group, GroupMembership models
│   ├── schemas/
│   │   ├── user.py                    ← UserCreate/Out, Token, DashboardPrefsOut/Update
│   │   ├── profile.py                 ← ProfileRead, ProfileUpdate
│   │   └── group.py                   ← GroupCreate/Update/Out/DetailOut, GroupMemberOut
│   ├── routers/
│   │   ├── auth.py                    ← POST /register, POST /login
│   │   ├── users.py                   ← GET /me, GET+PATCH /me/preferences, PATCH /me/color-mode, GET /me/groups
│   │   ├── profile.py                 ← GET+PUT /me (profile)
│   │   ├── admin.py                   ← User admin CRUD (admin-only)
│   │   ├── groups.py                  ← Group CRUD + member management (admin-only)
│   │   ├── settings.py                ← AI, doc limits, system prompts, appearance, themes (admin-only)
│   │   ├── services.py                ← GET /services (health status)
│   │   ├── plugins.py                 ← Generic plugin proxy (GET/PATCH /api/plugins/*)
│   │   ├── categories_proxy.py        ← Transparent proxy → doc-service /categories/*
│   │   └── documents_proxy.py         ← Transparent proxy → doc-service /documents/*
│   └── services/
│       ├── service_health.py          ← Background 30s health-check loop; caches /plugin/manifest per service
│       └── group_bootstrap.py         ← Ensures {service-id}-admin group exists for every registered service at startup
├── alembic/
│   ├── env.py                         ← Async migration runner
│   └── versions/                      ← Migration chain (see Database Models)
├── scripts/seed.py                    ← Seed test user
├── Dockerfile                         ← python:3.12-slim, non-root user 1001
└── STATUS.md
```

---

## Database Models

### `users`

| Column | Type | Constraints | Notes |
|--------|------|-------------|-------|
| `id` | String | PK, UUID | auto-generated |
| `email` | String | UNIQUE, indexed, NOT NULL | lowercased before storing |
| `hashed_password` | String | NOT NULL | bcrypt 13 rounds |
| `full_name` | String | nullable | sanitized max 128 chars |
| `is_active` | Boolean | default=True | soft-delete flag |
| `is_superuser` | Boolean | default=False | admin role; never exposed as-is (serialised as `is_admin`) |
| `dashboard_app_ids` | JSON | NOT NULL, default=[] | list of pinned service IDs |
| `color_mode` | String | nullable, default=NULL | user's preferred mode: "light" / "dark" / "system" / NULL (use admin default) |

Relationship: `profile` (one-to-one, cascade all+delete-orphan)

### `profiles`

| Column | Type | Constraints | Notes |
|--------|------|-------------|-------|
| `id` | String | PK, UUID | auto-generated |
| `user_id` | String | FK→users.id UNIQUE, cascade delete | one-to-one |
| `phone` | String(20) | nullable | validated format |
| `date_of_birth` | Date | nullable | 1900+ and not future |
| `position` | String(128) | nullable | job title |
| `address` | String(255) | nullable | |
| `updated_at` | DateTime(tz) | server_default=now(), onupdate=now() | |

### `groups`

| Column | Type | Constraints |
|--------|------|-------------|
| `id` | String | PK, UUID |
| `name` | String(128) | UNIQUE indexed, NOT NULL |
| `description` | String(512) | nullable |
| `created_at` | DateTime(tz) | server_default=now() |

### `group_memberships`

| Column | Type | Constraints |
|--------|------|-------------|
| `id` | String | PK, UUID |
| `group_id` | String | FK→groups.id, indexed, CASCADE |
| `user_id` | String | FK→users.id, indexed, CASCADE |
| `is_group_admin` | Boolean | NOT NULL, default=false | grants group-admin rights (manage group categories, delete shared docs) |
| `joined_at` | DateTime(tz) | server_default=now() |

Unique constraint: `(group_id, user_id)`

### Migration chain (must be applied in order)

| Rev ID | Slug |
|--------|------|
| `38efeff7c45a` | `create_users_table` |
| `676084df61d1` | `add_profiles_table` |
| `a3f9c2d14e87` | `add_groups_and_group_memberships` |
| `c7e8f9a0b1d2` | `add_dashboard_app_ids_to_users` |
| `dd6ad2f2c211` | `add_color_mode_to_users` |
| `e1f2a3b4c5d6` | `add_group_member_is_admin` |

---

## API Endpoints

### Auth (`/api/auth`) — public

| Method | Path | Auth | Description |
|--------|------|------|-------------|
| POST | `/api/auth/register` | — | Create account; returns `UserOut`; enforces password policy |
| POST | `/api/auth/login` | — | OAuth2 password flow; returns `{access_token, token_type}` |

### Users (`/api/users`) — authenticated

| Method | Path | Auth | Description |
|--------|------|------|-------------|
| GET | `/api/users/me` | user | Current user info → `UserOut` |
| GET | `/api/users/me/preferences` | user | Dashboard pinned app IDs → `{app_ids}` |
| PATCH | `/api/users/me/preferences` | user | Save pinned app IDs (max 50, slug-safe) |
| PATCH | `/api/users/me/color-mode` | user | Save colour mode preference ("light"/"dark"/"system") |
| GET | `/api/users/me/groups` | user | Groups current user belongs to → `list[UserGroupOut]` |

### Profile (`/api/profile`) — authenticated

| Method | Path | Auth | Description |
|--------|------|------|-------------|
| GET | `/api/profile/me` | user | Fetch profile; auto-creates if missing |
| PUT | `/api/profile/me` | user | Update profile fields |

### Admin — Users (`/api/admin`) — admin-only

| Method | Path | Description |
|--------|------|-------------|
| GET | `/api/admin/users` | List all users → `list[UserAdminOut]` |
| POST | `/api/admin/users` | Create user (with optional is_admin) |
| DELETE | `/api/admin/users/{user_id}` | Delete user (204) |
| PATCH | `/api/admin/users/{user_id}/active` | Toggle active status |

### Admin — Groups (`/api/admin/groups`) — admin-only

| Method | Path | Description |
|--------|------|-------------|
| GET | `/api/admin/groups` | List groups with member count |
| POST | `/api/admin/groups` | Create group |
| GET | `/api/admin/groups/{id}` | Group detail + members |
| PATCH | `/api/admin/groups/{id}` | Update name / description |
| DELETE | `/api/admin/groups/{id}` | Delete (cascades memberships) |
| POST | `/api/admin/groups/{id}/members/{user_id}` | Add member |
| DELETE | `/api/admin/groups/{id}/members/{user_id}` | Remove member |
| PATCH | `/api/admin/groups/{id}/members/{user_id}/admin` | Set/unset group admin role (body: `{ is_group_admin: bool }`) |

### Settings (`/api/settings`) — admin-only

| Method | Path | Description |
|--------|------|-------------|
| GET | `/api/settings/ai` | AI config (keys masked) |
| PATCH | `/api/settings/ai` | Update AI provider / credentials |
| POST | `/api/settings/ai/test` | Test AI connection |
| GET | `/api/settings/documents/limits` | PDF upload limits |
| PATCH | `/api/settings/documents/limits` | Update max PDF size |
| GET | `/api/settings/system-prompts` | All editable system prompts |
| PATCH | `/api/settings/system-prompts/{service_id}` | Update system prompt |
| GET | `/api/settings/appearance` | Active theme + default mode (auth) |
| PATCH | `/api/settings/appearance` | Update active theme + default mode (admin) |
| GET | `/api/settings/themes` | List all themes — built-in + custom (auth) |
| POST | `/api/settings/themes` | Create custom theme (admin) |
| PATCH | `/api/settings/themes/{id}` | Update custom theme label/colours (admin) |
| DELETE | `/api/settings/themes/{id}` | Delete custom theme (admin, 204) |

### Services (`/api/services`) — authenticated

| Method | Path | Description |
|--------|------|-------------|
| GET | `/api/services` | Health status of all registered services → `list[ServiceStatus]` |

### Plugins (`/api/plugins`) — authenticated, auth-per-plugin

| Method | Path | Description |
|--------|------|-------------|
| GET | `/api/plugins` | List plugins accessible to current user |
| GET | `/api/plugins/{id}/manifest` | Plugin manifest with settings JSON Schema (auth-gated) |
| GET | `/api/plugins/{id}/settings` | Proxy to feature `/plugin/settings` (auth-gated) |
| PATCH | `/api/plugins/{id}/settings` | Proxy to feature `/plugin/settings` (auth-gated) |

Auth: is_superuser OR member of group listed in manifest `required_groups`. Returns 404 (not 403) to hide existence.

### Documents and Categories — proxied

`/api/documents/*` and `/api/documents/categories/*` are transparently proxied to `doc-service:8001`. The backend injects `x-user-id`, `x-user-groups`, and `x-user-is-admin` headers. See `features/doc-service/CLAUDE.md` for the internal endpoint list.

---

## Security Standards

These standards are **non-negotiable**. Every change must comply.

### JWT

- **Algorithm**: RS256 (4096-bit RSA key pair, generated by `scripts/generate_jwt_keys.py`)
- **Keys**: PEM-encoded in `backend/.env` as `JWT_PRIVATE_KEY` / `JWT_PUBLIC_KEY` (gitignored)
- **Expiry**: 8 hours (`EXPIRE_MINUTES=480`) — never set longer; no refresh tokens
- **Claims**: `{sub: user_id, exp, iat}` — user_id is a UUID string
- **Validation**: `decode_access_token()` in `core/security.py`; called by `get_current_user`
- **Never**: set algorithm to `"none"`, disable `verify_exp`, or hardcode secrets in code

### Password hashing

- **Algorithm**: bcrypt, **13 rounds** (`bcrypt.gensalt(rounds=13)`)
- **Timing**: ~300 ms per hash (intentional brute-force resistance)
- **Never** use MD5, SHA1, or plain SHA256 for password storage

### Password policy (enforced in `UserCreate` schema)

All of the following must pass:
- ≥ 8 characters
- ≥ 1 uppercase (A–Z)
- ≥ 1 lowercase (a–z)
- ≥ 1 digit (0–9)
- ≥ 1 special character: `!@#$%^&*()\-_=+[]{}|;:'"<>?/\`~`
- No common words (password, secret, login, admin, test, qwerty, welcome, …)

### Input sanitization

Every user-supplied string stored in the database **must** pass through `core/sanitize.py`:

```python
sanitize_str(value, max_len=255)
# → strips whitespace; rejects null bytes (\x00); rejects control chars
#   (0x01–0x1F, 0x7F except \t \n \r); enforces max_len; returns None for ""

normalize_email(value)       # lowercase + strip
validate_phone(value)        # sanitize_str(max=20) + regex ^\+?[\d\s\-()\[\]]{7,20}$
validate_date_of_birth(v)    # must be ≥ 1900, not future
```

Apply via Pydantic `@field_validator` on all request schemas.

### SQL injection prevention

- Use SQLAlchemy ORM (bound parameters) — **never** raw SQL strings.
- If `text()` is needed, use `bindparam()` for all user-supplied values.
- **Never** use f-strings, `.format()`, or `%`-formatting for SQL.

### Admin route security

- Use `get_current_admin` dependency (checks `is_superuser`).
- Return **404** (not 403) for unauthorized access — hides both endpoint existence and permission model.

---

## Naming & Code Conventions

### Database

- **Tables**: lowercase, plural, snake_case (`users`, `group_memberships`, `document_category_assignments`)
- **Columns**: lowercase, snake_case
- **ORM models**: PascalCase, singular (`User`, `Group`, `GroupMembership`, `Document`)
- Primary keys: `id` (String UUID, auto-generated)
- Timestamps: `created_at` / `updated_at` / `joined_at` / `processed_at` — always timezone-aware

### Pydantic schemas

| Suffix | Purpose |
|--------|---------|
| `Create` | POST request body (user-supplied input) |
| `Update` | PATCH request body (partial update) |
| `Out` | API response (safe subset of model) |
| `AdminOut` | Extended response for admin endpoints |
| `Read` | GET response (same as `Out`, used for profiles) |

Always set `model_config = {"from_attributes": True}` on response schemas.
Use `validation_alias` when the ORM field name differs from the JSON key (e.g., `is_superuser` → `is_admin`).

### HTTP status codes

| Code | Use |
|------|-----|
| 200 | Successful GET / PATCH / PUT |
| 201 | Successful POST that creates a resource |
| 202 | Accepted (async processing started, e.g., document upload) |
| 204 | Successful DELETE or action with no response body |
| 400 | Bad request (duplicates, invalid data beyond Pydantic) |
| 401 | Missing / invalid JWT |
| 404 | Not found **and** admin routes when not admin |
| 413 | Payload too large (file exceeds limit) |
| 415 | Unsupported media type (not a PDF) |
| 422 | Pydantic validation failure (FastAPI default) |
| 502 | Downstream service unreachable |
| 503 | Service unavailable (queue stopped, AI error) |
| 504 | Gateway timeout |

### Backend code style

- Async/await for **all** I/O (DB, HTTP, file).
- `raise HTTPException(status_code=..., detail="...")` for all errors.
- Response models always declared in route decorator: `@router.get("/path", response_model=XOut)`.
- Background tasks via `BackgroundTasks` param; tasks open their own `AsyncSessionLocal` session.
- Commit + refresh pattern after mutations:
  ```python
  await db.commit()
  await db.refresh(obj)
  ```

---

## Default Values & Limits

| Parameter | Value | Location |
|-----------|-------|----------|
| JWT expiry | 480 min (8 h) | `core/security.py` |
| Bcrypt rounds | 13 | `core/security.py` |
| User `color_mode` default | NULL (falls back to admin default_mode, then system) | `models/user.py` |
| Max dashboard pinned apps | 50 | `schemas/user.py` |
| App ID max length | 64 chars | `schemas/user.py` |
| App ID allowed chars | `[a-zA-Z0-9_\-]` | `schemas/user.py` |
| full_name max length | 128 chars | `schemas/user.py` |
| Group name max length | 128 chars | `schemas/group.py` |
| Group description max | 512 chars | `schemas/group.py` |
| Phone max length | 20 chars | `sanitize.py` |
| Position max length | 128 chars | `schemas/profile.py` |
| Address max length | 255 chars | `schemas/profile.py` |