[mjcbeckett]

Thanks, "missing primitive" is exactly how I think about it too.

On idempotency: not solved yet at the API level. Each POST creates a new document so a retry would create a duplicate. Adding an idempotency key header is on the roadmap, it becomes essential once agents run unsupervised. For now the MCP tool response includes the document_id so agents can check status before retrying.

On markdown vs PDF: almost entirely markdown so far. Agents generate text naturally so markdown in is the obvious path. The pdf_url option exists for when you already have a templated doc from another system and just need the signing part.