5648f81431 fixed this exact server-side seal (Slack closes a native stream
after a few minutes of a long turn, live-observed at ~5m20s; the lifetime
is not documented) for the native task-card stream: on
message_not_in_streaming_state from appendStream, drop the dead ts and
start a fresh stream, seeded with the full current content so nothing is
lost.
send_draft — the plain-text native streaming path used when task cards
are not enabled — hits the identical seal but never got the fix: its
generic except block only recognizes the feature-gate markers
(not_allowed, missing_scope, ...) and otherwise just logs debug and
returns failure. gateway/stream_consumer_transport.py's
_send_draft_frame() docstring is explicit that "any failure permanently
disables drafts for this run" — so a long turn streaming as plain text
degrades to the edit-based fallback for its remainder exactly the way
the task-card bug did before 5648f81431.
Mirror the task-card fix: on message_not_in_streaming_state from
chat.appendStream, drop the dead ts and _start_stream() a fresh one
seeded with the full accumulated text (not just the delta), so the next
frame's delta still resumes correctly. One reopen per frame; a second
rejection propagates as a real failure, matching the twin's behavior.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
(cherry picked from commit 2b4ff4e23bdf684d2fde1a9512f11dcd7ef99c42)
d5a2d1f069