# REST API Contract

Base URL: `/api` behind web proxy, or server root directly in local/dev.

Authentication:
- If `ADMIN_TOKEN` is set on server, send `Authorization: Bearer <token>`.
- If `ADMIN_TOKEN` is unset, API is open for local/dev use.

Content type:
- Requests with bodies use `application/json`.
- Responses are JSON unless noted otherwise.

## Health + Auth

### `GET /health`
- Response: `{ "ok": true }`

### `GET /v1/auth/session`
- Response: `{ "authenticated": true, "mode": "open" | "token" }`

## Models

### `GET /v1/models`
- Response:
```json
{
  "providers": {
    "openai": { "models": ["gpt-4.1-mini"], "loadedAt": "2026-02-14T00:00:00.000Z", "error": null },
    "anthropic": { "models": ["claude-3-5-sonnet-latest"], "loadedAt": null, "error": null },
    "xai": { "models": ["grok-3-mini"], "loadedAt": null, "error": null }
  }
}
```

## Chats

### `GET /v1/chats`
- Response: `{ "chats": ChatSummary[] }`

### `POST /v1/chats`
- Body: `{ "title"?: string }`
- Response: `{ "chat": ChatSummary }`

### `PATCH /v1/chats/:chatId`
- Body: `{ "title": string }`
- Response: `{ "chat": ChatSummary }`
- Not found: `404 { "message": "chat not found" }`

### `POST /v1/chats/title/suggest`
- Body:
```json
{
  "chatId": "chat-id",
  "content": "user request text"
}
```
- Response: `{ "chat": ChatSummary }`

Behavior notes:
- If the chat already has a non-empty title, server returns the existing chat unchanged.
- Server always uses OpenAI `gpt-4.1-mini` to generate a one-line title (up to ~4 words), updates the chat title, and returns the updated chat.

### `DELETE /v1/chats/:chatId`
- Response: `{ "deleted": true }`
- Not found: `404 { "message": "chat not found" }`

### `GET /v1/chats/:chatId`
- Response: `{ "chat": ChatDetail }`

### `POST /v1/chats/:chatId/messages`
- Body:
```json
{
  "role": "system|user|assistant|tool",
  "content": "string",
  "name": "optional",
  "metadata": {}
}
```
- Response: `{ "message": Message }`

## Chat Completions (non-streaming)

### `POST /v1/chat-completions`
- Body:
```json
{
  "chatId": "optional-chat-id",
  "provider": "openai|anthropic|xai",
  "model": "string",
  "messages": [
    { "role": "system|user|assistant|tool", "content": "string", "name": "optional" }
  ],
  "temperature": 0.2,
  "maxTokens": 256
}
```
- Response:
```json
{
  "chatId": "chat-id-or-null",
  "provider": "openai",
  "model": "gpt-4.1-mini",
  "message": { "role": "assistant", "content": "..." },
  "usage": { "inputTokens": 10, "outputTokens": 20, "totalTokens": 30 },
  "raw": {}
}
```

Behavior notes:
- If `chatId` is present, server validates chat existence.
- For `chatId` calls, server stores only *new* non-assistant messages from provided history to avoid duplicates.
- Server persists final assistant output and call metadata (`LlmCall`) in DB.
- Server updates chat-level model metadata on each call: `lastUsedProvider`/`lastUsedModel`; first successful/failed call also initializes `initiatedProvider`/`initiatedModel` if unset.
- For `openai` and `xai`, backend enables tool use during chat completion with an internal system instruction.
- Available tool calls for chat: `web_search` and `fetch_url`.
- `web_search` uses Exa and returns ranked results with per-result summaries/snippets.
- `fetch_url` fetches a URL and returns plaintext page content (HTML converted to text server-side).
- When a tool call is executed, backend stores a chat `Message` with `role: "tool"` and tool metadata (`metadata.kind = "tool_call"`), then stores the assistant output.
- `anthropic` currently runs without server-managed tool calls.

## Searches

### `GET /v1/searches`
- Response: `{ "searches": SearchSummary[] }`

### `POST /v1/searches`
- Body: `{ "title"?: string, "query"?: string }`
- Response: `{ "search": SearchSummary }`

### `DELETE /v1/searches/:searchId`
- Response: `{ "deleted": true }`
- Not found: `404 { "message": "search not found" }`

### `GET /v1/searches/:searchId`
- Response: `{ "search": SearchDetail }`

### `POST /v1/searches/:searchId/run`
- Body:
```json
{
  "query": "optional override",
  "title": "optional override",
  "type": "auto|fast|deep|instant",
  "numResults": 10,
  "includeDomains": ["example.com"],
  "excludeDomains": ["example.org"]
}
```
- Response: `{ "search": SearchDetail }`

Search run notes:
- Backend executes Exa search and Exa answer.
- Persists answer text/citations + ranked results.
- If both search and answer fail, endpoint returns an error.

## Type Shapes

`ChatSummary`
```json
{
  "id": "...",
  "title": null,
  "createdAt": "...",
  "updatedAt": "...",
  "initiatedProvider": "openai|anthropic|xai|null",
  "initiatedModel": "string|null",
  "lastUsedProvider": "openai|anthropic|xai|null",
  "lastUsedModel": "string|null"
}
```

`Message`
```json
{
  "id": "...",
  "createdAt": "...",
  "role": "system|user|assistant|tool",
  "content": "...",
  "name": null,
  "metadata": null
}
```

`ChatDetail`
```json
{
  "id": "...",
  "title": null,
  "createdAt": "...",
  "updatedAt": "...",
  "initiatedProvider": "openai|anthropic|xai|null",
  "initiatedModel": "string|null",
  "lastUsedProvider": "openai|anthropic|xai|null",
  "lastUsedModel": "string|null",
  "messages": [Message]
}
```

`SearchSummary`
```json
{ "id": "...", "title": null, "query": null, "createdAt": "...", "updatedAt": "..." }
```

`SearchDetail`
```json
{
  "id": "...",
  "title": "...",
  "query": "...",
  "createdAt": "...",
  "updatedAt": "...",
  "requestId": "...",
  "latencyMs": 123,
  "error": null,
  "answerText": "...",
  "answerRequestId": "...",
  "answerCitations": [],
  "answerError": null,
  "results": []
}
```

For streaming contracts, see `docs/api/streaming-chat.md`.