You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
SDKArea: what it touches
ImprovementsKind: in v2.1.239,
ImprovementsSection of the release
What
The source field on UserPromptSubmit no longer says it is set only for Anthropic-internal sessions during a trial; it now says payloads may omit it while the field rolls out. The setModel systemPrompt replacement no longer claims only the subprocess stdin transport honors it.
Details
setModel now states that transports which do not implement the replacement acknowledge success without applying it, so a success response is not proof the prompt changed.
Evidence
Payloads may omit it while the field rolls out.
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
