You'll noticeTier: how much it should matter to you
4Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
Headless ModeArea: what it touches
Bug FixesKind: in v2.1.227,
What probably matters to youSection of the release
What
If a message cannot be written to the headless output stream, Claude now writes an Error: line to stderr, marks the turn's summary as failed, and in stream-json mode emits a result object with an error_during_execution subtype built by a shared helper.
Details
The stderr line begins Could not write a message to the output stream.
Paired with a tengu_headless_fatal_error event carrying the site, message type, control subtype, drained message count, outstanding stdout bytes and whether stdout was destroyed.
None of this existed in v2.1.226.
Evidence
Could not write a message to the output stream
Strings lifted out of the shipped bundle, so the claim above can be checked against them.
