Round 2 of the approval-turn stuck-stream hunt. Round 1 (interim-marked
acks) fixed the draft-hijack-by-matching path — live logs confirm the
absorption fallback no longer fires — but the freeze persisted because
of a second, deeper defect on the same codepath:
_consume_prompt_response executes ON the transport read loop (inbound
frame -> _handle_frame -> _inbound handler). The handler awaited
self.send() for its '✅ Approved once' ack — but send() blocks on an
outbound_result future that ONLY the read loop can resolve, and the
read loop is blocked inside this very handler. Guaranteed self-deadlock
for the full outbound timeout (30s) on EVERY button tap. While wedged,
everything on the transport starved: draft appends (the frozen stream
right after approving), sibling approval-card sends (timed out into
'possibly-delivered' — the observed double-approval ambiguity), and the
turn's seal (timed out ambiguous -> plain-send fallback -> duplicate
final). Log signature was the tell: card-send timeout at tap time, no
absorption INFO, no seal-failed WARNING, no suppression line.
Fix: _send_lifecycle_ack() — acks ride a background task with strong
ref retention; the handler returns immediately and the read loop keeps
consuming, so the ack's own result frame resolves normally. Applied to
all six lifecycle sends (approval ack, slash-confirm ack + result text,
clarify acks, expiry notice). Acks are cosmetic by contract; failure
logs at debug and never breaks the reader.
Tests: new deadlock-shape test (gated transport send; handler must
return within 1s and the ack must still egress afterwards — RED on the
awaited version via TimeoutError at the exact deadlock), prior 3 tests
green with a yield for the background task. Targeted sweep 203/203.
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