What
A new tool that lets Claude post structured checkpoint messages to the user, designed for async workflows where the user may only be reading a compact view of the conversation.
Usage: Claude calls SendUserMessage with a message, optional file attachments, and a status (proactive for push notifications, normal for replies).
Details
- Messages are concise, outcome-focused checkpoints — like commit messages, not recaps
- Supports markdown formatting and file attachments (screenshots, diffs, logs)
proactivestatus is for reaching the user's phone when they're away (task done, blockers, questions)normalstatus is for replies to active conversations- Tied to a new
defaultViewsetting:"chat"shows only SendUserMessage checkpoints,"transcript"shows the full output
Evidence
New tool constant and prompt definition (search for "SendUserMessage")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.