Skip to main content
A message has a role — user or assistant — and content. You post user messages; assistant messages are produced by runs.
The response is 202 with a run_id — the turn has started, not finished.

​
Attaching files

To hand the assistant a file, upload it first and pass its handle in file_ids:
The assistant sees the file, and can pass its handle to a file-reading tool like extract (wired as a patch). Attachments are PDFs or images, at most 10 MiB each, up to 10 per message. Files stay available for the life of the thread.

​
Posting resumes a paused run

If the thread has a run waiting on a question, your message is the answer and that run continues. If it has no paused run, a new run starts. You do not choose between these; the runtime does. The exception is a run waiting for a write approval. There, a message is refused:
Approve or reject first — see Confirmations.

​
Reading them

GET /v1/loom/threads/:thread_id/messages returns the thread’s messages in order. For what the agent did rather than what it said, read the trace instead.

​
Titles

The first user message becomes the thread’s title, truncated to 80 characters, for your history list. It is set once and not revised.

​
Streaming

If the agent has streaming enabled and realtime is configured, assistant content arrives as message.delta events during the run, then a final message.completed. Without realtime, poll the run and read the message when it closes.

​
Rich messages

An assistant reply can carry structured data alongside its text. When it does, the message has a parts array — an ordered list of text parts and data parts. A data part is { "type": "data", "kind", "payload", "ref" }: Patchwork sends the kind and a structured payload, and you render it — a chart, a table, a card, whatever your UI does with that kind. We never send markup or images.
content is always the plain-text fallback, so a client that doesn’t recognise a kind still shows something. A block reaches realtime subscribers as a message.block event; on reload it is on the message itself. Two things produce a data part: a patch tagged render: { kind } (its result becomes the block) and the native render_* tools the model can call. Rendering and any interactivity are yours — if a block needs to tell the agent something, just send a normal message.