You'll notice
Useful3 Signal2
Stream output docs now explain why one reply arrives as several messages sharing an id.
What's wrong with this entry?
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parent_tool_use_idstop_reason
What
The assistant-message schema now states that one message is emitted per completed content block, that consecutive messages can share the same message.id, that stop_reason is null and usage is not final on those, and that parent_tool_use_id is set inside a subagent.
Evidence
the turn's stop reason and total usage arrive on the result message
Strings lifted out of the shipped bundle, so the claim above can be checked against them.