<!-- generated-by: gsd-doc-writer -->
# API Reference

FamilySync exposes a Hono HTTP API served on port 3000. All `/api/*` routes require an authenticated session (OIDC via Authelia, or `DEV_AUTH_BYPASS=true` for local development). Unauthenticated requests to protected routes receive a `302` redirect to Authelia's authorize endpoint, not a `401`, except where noted.

## Authentication

The API uses OIDC session cookies managed by `@hono/oidc-auth`. The authorization-code + PKCE flow is handled transparently:

1. The PWA navigates to `GET /api/login`. This route sits under `/api/*`, where the `@hono/oidc-auth` guard is mounted.
2. For a request with no valid session cookie, the OIDC middleware intercepts it before the route handler runs and 302-redirects to Authelia's authorize endpoint.
3. Authelia posts the authorization code to `GET /callback`, which exchanges it for tokens and sets an `httpOnly; Secure; SameSite` session cookie, then continues back to `/api/login` — whose handler now redirects to `/` (the app shell).
4. All subsequent `/api/*` requests carry the session cookie automatically. (The root `/` and static assets are served outside the `/api/*` guard.)

**Dev bypass:** When `DEV_AUTH_BYPASS=true` and `NODE_ENV != production`, the OIDC guard is disabled and a fixed dev user (id `1`) is injected into every request. Never enable in production.

No API key or `Authorization` header is used. Credentials are never included in response bodies.

## Endpoints Overview

| Method | Path | Auth | Description |
|--------|------|------|-------------|
| GET | `/health` | None | DB liveness check |
| GET | `/callback` | None | OIDC authorization-code exchange |
| GET | `/api/login` | OIDC | Login entry point, redirects to `/` |
| GET | `/api/me` | OIDC | Current user identity and color |
| GET | `/api/events` | OIDC | Windowed calendar occurrences |
| POST | `/api/events/create` | OIDC | Enqueue a new event write |
| PATCH | `/api/events/:uid/edit` | OIDC | Enqueue an event update |
| DELETE | `/api/events/:uid` | OIDC | Enqueue an event delete |
| GET | `/api/events/sync-status` | OIDC | Outbox status for a UID |
| GET | `/api/events/writable-calendars` | OIDC | Calendars the member can write to |
| GET | `/api/lists` | OIDC | All lists accessible to the member |
| POST | `/api/lists` | OIDC | Create a list |
| PATCH | `/api/lists/:id` | OIDC | Update list name or sharing |
| DELETE | `/api/lists/:id` | OIDC | Delete a list (owner only) |
| GET | `/api/lists/:id/items` | OIDC | All items in a list |
| POST | `/api/lists/:id/items` | OIDC | Add an item to a list |
| PATCH | `/api/list-items/:itemId` | OIDC | Update a single list item field |
| DELETE | `/api/list-items/:itemId` | OIDC | Delete a list item |
| GET | `/api/sse/heartbeat` | OIDC | SSE heartbeat stream |
| GET | `/api/sse/lists` | OIDC | Scoped live-list SSE stream |
| GET | `/api/push/vapid-public-key` | OIDC | VAPID public key for push subscribe |
| POST | `/api/push/subscription` | OIDC | Register a push subscription |
| DELETE | `/api/push/subscription` | OIDC | Remove push subscriptions for caller |

---

## Health

### `GET /health`

Unauthenticated. Performs a `SELECT 1` against MariaDB to prove connectivity.

**Response 200**
```json
{ "ok": true, "db": "up" }
```

**Response 503** (DB unreachable)
```json
{ "ok": false, "db": "down" }
```

---

## Identity

### `GET /api/me`

Returns the authenticated member's identity and their assigned color.

Display name is derived from OIDC claims in priority order: `name` → `preferred_username` → `email` → `sub`. The user row is upserted on first visit (keyed on `oidc_iss` + `oidc_sub`).

**Response 200**
```json
{
  "user": {
    "id": 1,
    "displayName": "Lucas",
    "color": "#4A90D9"
  }
}
```

**Error responses:** `401` if the session is invalid.

---

## Calendar Events

Calendar data is read from a MariaDB cache populated by the CalDAV broker poller. Write operations enqueue outbox rows; the outbox worker dispatches them to Fastmail CalDAV asynchronously. Clients receive `202 Accepted` immediately and poll `GET /api/events/sync-status` to confirm settlement.

### `GET /api/events?start=YYYY-MM-DD&end=YYYY-MM-DD`

Returns a flat array of concrete event occurrences for the given date window. Recurring events are expanded server-side via `rrule`. The window is capped at 90 days. Returns events from calendars the member owns plus any shared (family) calendars.

**Query parameters**

| Parameter | Required | Format | Notes |
|-----------|----------|--------|-------|
| `start` | Yes | `YYYY-MM-DD` | Window start (inclusive) |
| `end` | Yes | `YYYY-MM-DD` | Window end (exclusive); max 90 days from start |

**Response 200**
```json
{
  "occurrences": [
    {
      "uid": "abc123@familysync",
      "title": "Doctor appointment",
      "allDay": false,
      "start": "2025-06-15T09:00:00Z",
      "end": "2025-06-15T10:00:00Z",
      "calendarId": 3,
      "calendarName": "Personal",
      "color": "#4A90D9",
      "isShared": false,
      "userId": 1,
      "ownerName": "Lucas"
    }
  ]
}
```

**Error responses:** `400` if the window is invalid or exceeds 90 days; `401` unauthorized; `503` DB error.

---

### `POST /api/events/create`

Enqueues a new event for creation on Fastmail CalDAV. Returns `202` immediately with the assigned UID.

**Request body**

```json
{
  "title": "Family dinner",
  "allDay": false,
  "start": "2025-06-20T18:00:00Z",
  "end": "2025-06-20T20:00:00Z",
  "location": "Home",
  "description": "Optional notes",
  "recurrence": "weekly",
  "recurrenceUntil": "2025-12-31",
  "recurrenceCount": 10,
  "calendarUrl": "https://caldav.fastmail.com/dav/.../calendar/"
}
```

| Field | Type | Required | Constraints |
|-------|------|----------|-------------|
| `title` | string | Yes | 1–255 characters |
| `allDay` | boolean | Yes | |
| `start` | string | Yes | ISO datetime or `YYYY-MM-DD` for all-day; max 64 chars |
| `end` | string | Yes | ISO datetime or `YYYY-MM-DD` for all-day; max 64 chars |
| `location` | string | No | Max 2000 characters |
| `description` | string | No | Max 2000 characters |
| `recurrence` | string | No | `none` \| `daily` \| `weekly` \| `monthly` \| `yearly` |
| `recurrenceUntil` | string | No | `YYYY-MM-DD` — maps to RRULE `UNTIL` |
| `recurrenceCount` | integer | No | ≥ 1 — maps to RRULE `COUNT` |
| `calendarUrl` | string | No | CalDAV collection URL (max 1024); defaults to member's first personal calendar |

`calendarUrl` must belong to the authenticated member or be the shared family calendar. Requests for another member's personal calendar return `403`.

**Response 202**
```json
{ "uid": "f47ac10b-58cc-4372-a567-0e02b2c3d479@familysync" }
```

**Error responses:** `401` unauthorized; `403` calendar access denied; `422` no writable calendar found; `503` DB error.

---

### `PATCH /api/events/:uid/edit`

Enqueues an update to an existing event. Body shape is identical to `POST /api/events/create`. Returns `202` with the (possibly new) UID.

If `calendarUrl` in the body differs from the event's current calendar, the operation is a calendar move: a delete+create pair is enqueued atomically. A new UID is assigned and returned.

**Path parameter:** `uid` — the event UID as returned by `POST /api/events/create` or `GET /api/events`.

**Request body:** Same schema as `POST /api/events/create`.

**Response 202**
```json
{ "uid": "f47ac10b-58cc-4372-a567-0e02b2c3d479@familysync" }
```

**Error responses:** `401` unauthorized; `403` access denied; `404` event not found; `503` DB error.

---

### `DELETE /api/events/:uid`

Enqueues a delete for an existing event. Returns `202` immediately.

**Path parameter:** `uid` — the event UID.

**Response 202**
```json
{ "uid": "f47ac10b-58cc-4372-a567-0e02b2c3d479@familysync" }
```

**Error responses:** `401` unauthorized; `403` access denied; `404` event not found; `503` DB error.

---

### `GET /api/events/sync-status?uid=<uid>`

Returns the outbox status for a given UID, scoped to the authenticated member. Used by the PWA to confirm write settlement after `202` responses.

If no outbox row exists, the write has settled (or never existed).

**Query parameters**

| Parameter | Required | Notes |
|-----------|----------|-------|
| `uid` | Yes | 1–512 characters |

**Response 200**
```json
{ "uid": "f47ac10b-...", "status": "done" }
```

Possible `status` values: `pending` \| `failed` \| `dead` \| `done`.

When `status` is `failed` or `dead`, an `error` field is included:
```json
{ "uid": "f47ac10b-...", "status": "dead", "error": "CalDAV 409 conflict" }
```

**Error responses:** `401` unauthorized; `503` DB error.

---

### `GET /api/events/writable-calendars`

Returns the authoritative writable calendar set for the authenticated member: their own personal calendar(s) and the shared family calendar. Another member's personal calendar is never included.

**Response 200**
```json
{
  "calendars": [
    {
      "url": "https://caldav.fastmail.com/dav/.../Personal/",
      "displayName": "Personal",
      "color": "#4A90D9",
      "isShared": false
    },
    {
      "url": "https://caldav.fastmail.com/dav/.../Family/",
      "displayName": "Family",
      "color": "#F25C7A",
      "isShared": true
    }
  ]
}
```

**Error responses:** `401` unauthorized; `503` DB error.

---

## Lists

Lists are stored in MariaDB. A list can be private (owner-only) or shared (all household members). When `isShared: true`, share rows are created automatically for every other member — there is no client-facing shares endpoint.

### `GET /api/lists`

Returns all lists the authenticated member owns or has been shared. Includes item counts per list.

**Response 200**
```json
{
  "lists": [
    {
      "id": 1,
      "name": "Groceries",
      "isShared": true,
      "ownerId": 1,
      "activeCount": 5,
      "doneCount": 2,
      "createdAt": "2025-06-01T10:00:00.000Z",
      "updatedAt": "2025-06-10T08:00:00.000Z"
    }
  ]
}
```

**Error responses:** `401` unauthorized; `503` DB error.

---

### `POST /api/lists`

Creates a new list. If `isShared: true` (the default), share rows are auto-inserted for all other members.

**Request body**

```json
{ "name": "Gift Ideas", "isShared": true }
```

| Field | Type | Required | Constraints |
|-------|------|----------|-------------|
| `name` | string | Yes | 1–255 characters |
| `isShared` | boolean | No | Default: `true` |

**Response 201**
```json
{
  "id": 2,
  "name": "Gift Ideas",
  "isShared": true,
  "ownerId": 1,
  "activeCount": 0,
  "doneCount": 0,
  "createdAt": "2025-06-10T12:00:00.000Z",
  "updatedAt": "2025-06-10T12:00:00.000Z"
}
```

**Error responses:** `401` unauthorized; `503` DB error.

---

### `PATCH /api/lists/:id`

Updates a list's `name` and/or `isShared`. At least one field must be present. Only the list owner can change `isShared`; a sharee may rename.

Visibility changes reconcile share rows automatically:
- `false → true`: inserts share rows for all other members.
- `true → false`: deletes all non-owner share rows.

**Path parameter:** `id` — integer list ID.

**Request body** (at least one field required)

```json
{ "name": "Weekly Groceries", "isShared": false }
```

**Response 200**
```json
{
  "id": 1,
  "name": "Weekly Groceries",
  "isShared": false,
  "ownerId": 1,
  "createdAt": "2025-06-01T10:00:00.000Z",
  "updatedAt": "2025-06-10T13:00:00.000Z"
}
```

**Error responses:** `401` unauthorized; `403` access denied or sharee attempted `isShared` change; `404` list not found; `503` DB error.

---

### `DELETE /api/lists/:id`

Deletes a list. Owner-only. Cascades to all items and share rows.

**Path parameter:** `id` — integer list ID.

**Response 200**
```json
{ "id": 1 }
```

**Error responses:** `401` unauthorized; `403` access denied (non-owner); `404` list not found; `503` DB error.

---

### `GET /api/lists/:id/items`

Returns all items in a list, ordered by fractional rank ascending. Accessible to owner and sharees.

**Path parameter:** `id` — integer list ID.

**Response 200**
```json
{
  "items": [
    {
      "id": 10,
      "listId": 1,
      "text": "Milk",
      "checked": false,
      "rank": "a0",
      "createdAt": "2025-06-10T10:00:00.000Z",
      "updatedAt": "2025-06-10T10:00:00.000Z"
    }
  ]
}
```

**Error responses:** `401` unauthorized; `403` access denied; `404` list not found; `503` DB error.

---

### `POST /api/lists/:id/items`

Adds an item to a list at the bottom of the active (unchecked) section. Accessible to owner and sharees.

**Path parameter:** `id` — integer list ID.

**Request body**

```json
{ "text": "Eggs" }
```

| Field | Type | Required | Constraints |
|-------|------|----------|-------------|
| `text` | string | Yes | 1–500 characters (plain text only) |

**Response 201**
```json
{
  "id": 11,
  "listId": 1,
  "text": "Eggs",
  "checked": false,
  "rank": "a1",
  "createdAt": "2025-06-10T14:00:00.000Z",
  "updatedAt": "2025-06-10T14:00:00.000Z"
}
```

**Error responses:** `401` unauthorized; `403` access denied; `404` list not found; `503` DB error.

---

### `PATCH /api/list-items/:itemId`

Updates exactly one field of a list item (last-write-wins). Exactly one of `checked`, `text`, or `position` must be present.

Special case: setting `checked: false` (uncheck) also recomputes the item's rank to place it at the bottom of the active section.

**Path parameter:** `itemId` — integer item ID.

**Request body** (exactly one field)

```json
{ "checked": true }
```

or

```json
{ "text": "Whole milk" }
```

or

```json
{ "position": "a0V" }
```

| Field | Type | Constraints |
|-------|------|-------------|
| `checked` | boolean | |
| `text` | string | 1–500 characters |
| `position` | string | Fractional rank string, 1–255 characters |

**Response 200** — updated item shape (same as `POST /api/lists/:id/items` response).

**Error responses:** `401` unauthorized; `403` access denied; `404` item not found; `503` DB error.

---

### `DELETE /api/list-items/:itemId`

Deletes a list item permanently. Accessible to list owner and sharees. No soft-delete; deletion is final.

**Path parameter:** `itemId` — integer item ID.

**Response 200**
```json
{ "id": 11 }
```

**Error responses:** `401` unauthorized; `403` access denied; `404` item not found; `503` DB error.

---

## Server-Sent Events

SSE streams use `Content-Type: text/event-stream`. The client should reconnect on disconnect with bounded backoff (handled by the `useListSSE` hook in the PWA).

### `GET /api/sse/heartbeat`

Streams `heartbeat` events every 10 seconds indefinitely. Used as a Pangolin tunnel smoke test.

**Event format**
```
event: heartbeat
id: 0
data: {"ts":"2025-06-10T14:00:00.000Z","id":0}
```

---

### `GET /api/sse/lists`

Scoped live-list fan-out stream. Delivers mutation events only for lists the authenticated member can access (owned + shared). Events for other members' private lists are never delivered.

A `heartbeat` event is sent every 30 seconds to keep the Pangolin connection alive.

**Event types**

| Event type | Payload |
|------------|---------|
| `list:updated` | `{ type, listId, payload: { id, name } }` |
| `list:deleted` | `{ type, listId, payload: { id } }` |
| `item:added` | `{ type, listId, payload: { id, listId, text } }` |
| `item:updated` | `{ type, listId, payload: { id, listId } }` |
| `item:deleted` | `{ type, listId, payload: { id } }` |
| `heartbeat` | `{ ts }` |

**Event format example**
```
event: item:added
id: 1-1718020800000
data: {"type":"item:added","listId":1,"payload":{"id":11,"listId":1,"text":"Eggs"}}
```

The PWA treats these events as cache invalidation signals and full-refetches via TanStack Query. Event payloads are not used directly for cache updates.

**Error responses:** `401` if session is invalid (returned as JSON before the stream opens).

---

## Push Notifications

Push uses VAPID direct push (no FCM broker). The PWA must be installed to the home screen on iOS 16.4+ for push to function. `pushManager.subscribe()` must be called inside a user gesture handler.

### `GET /api/push/vapid-public-key`

Returns the server's VAPID public key. The public key is non-secret and required by the browser to call `pushManager.subscribe()`.

**Response 200**
```json
{ "publicKey": "BNF8dFt..." }
```

---

### `POST /api/push/subscription`

Registers a Web Push subscription for the authenticated member. Upserts on `endpoint` — re-subscribing from the same device updates keys without creating duplicate rows. The `userId` is derived from the OIDC session and never accepted from the request body.

**Request body**

```json
{
  "endpoint": "https://fcm.googleapis.com/fcm/send/...",
  "keys": {
    "p256dh": "BNF8dFt...",
    "auth": "tBHItJI..."
  }
}
```

| Field | Type | Required | Constraints |
|-------|------|----------|-------------|
| `endpoint` | string (URL) | Yes | Max 2048 characters |
| `keys.p256dh` | string | Yes | 1–512 characters |
| `keys.auth` | string | Yes | 1–256 characters |

**Response 201**
```json
{ "ok": true }
```

**Error responses:** `401` unauthorized; `503` DB error.

---

### `DELETE /api/push/subscription`

Removes all push subscription rows for the authenticated member. Cannot affect another member's subscriptions.

**Response 200**
```json
{ "ok": true }
```

**Error responses:** `401` unauthorized; `503` DB error.

---

## Error Codes

All error responses use a consistent JSON envelope.

```json
{ "error": "Human-readable message" }
```

| HTTP Status | Meaning |
|-------------|---------|
| `400` | Invalid request parameters (e.g., malformed date window) |
| `401` | Session missing or invalid |
| `403` | Authenticated but not authorized (wrong owner, sharee attempted owner-only op) |
| `404` | Resource not found |
| `422` | Valid request but cannot be fulfilled (e.g., user has no calendar configured) |
| `503` | DB or downstream service unavailable |

Zod validation failures return `400` with a structured body from `@hono/zod-validator` rather than the `{ "error": "..." }` envelope.

---

## Rate Limits

No rate limiting is configured in the application layer. <!-- VERIFY: confirm whether Pangolin/Newt or Authelia enforce rate limits at the network edge -->