API overview

Paddock has three network surfaces, and it matters which one you want:

Surface	Endpoint	What it’s for
REST	/api/*	Reads, project/chat/trigger management, git, instance config, attachment upload + serve.
WebSocket	/ws	The live chat turn: sending a message, streamed replies, tool events, cancel, slash commands, the queue.
MCP	/mcp	The external Management API — Paddock as an MCP server for other agents.

The split to remember: REST manages, the WebSocket converses. Sending a message is not a REST call — it is a chat:send frame over /ws. The one place they meet is attachments: upload the bytes over HTTP (POST /api/projects/:slug/chats/:sessionId/upload), then reference the returned file ids in the chat:send frame.

The endpoint list

The full, authoritative REST reference is the HTTP API reference — Swagger UI over an OpenAPI 3 document that is generated from the server’s Fastify route schemas. A new or changed route shows up there automatically, which is why it, and not a page like this one, is the endpoint list.

It’s a static, read-only reference for the latest release, so “Try it out” is disabled. To exercise the API against your own instance, run Paddock with PADDOCK_OPENAPI_ENABLED=1 (it is opt-in, off by default) and open /open-api on that instance — same document, live, with the raw spec at /open-api.json.

Authentication

Every request passes through the auth layer (packages/server/src/auth.ts) chosen by PADDOCK_AUTH_MODE (see CONFIGURATION.md and AUTH.md):

• In none mode (default) every request is the frozen anonymous principal — the API is fully open.
• In trusted-header / jwt modes the proxy/IdP identity becomes req.user, and per-user read-state (unread/seen) is keyed by username.
• GET /api/health is always exempt (liveness probe).
• There is no per-resource authorization — chat visibility is deliberately not gated (#189). “Auth” means “the configured mode must admit the request”, not “this principal owns this chat”.

The WebSocket at /ws is registered behind the same auth hook, so the mode you configure covers both surfaces. The security schemes advertised in the OpenAPI document reflect whichever mode the instance generating it was running.

Responses are JSON unless noted; :slug/:sessionId errors return { error, code } with 404 (not found), 409 (exists), or 400 (invalid); unexpected errors return 500.

The WebSocket

The /ws frame protocol — envelope, routing block, and every client→server and server→client frame — is documented at WebSocket protocol.

It lives on its own page because @fastify/swagger can only describe HTTP routes: the WebSocket contract cannot appear in the generated spec, so it stays hand-maintained.

MCP (/mcp)

Paddock can expose itself as an MCP server at /mcp, letting other agents drive it as a tool. Those routes are deliberately hidden from the OpenAPI document (they are a transport, not a REST resource), so /mcp — how to enable it, its clients, scopes and tools — is documented separately.