The agent emits a bare control marker (NO_REPLY / [SILENT] / …) when it
intentionally chooses not to reply. The gateway's whole-response filter
(is_intentional_silence_agent_result) suppresses this on the non-streaming
delivery path, but the streaming path (GatewayStreamConsumer) had no silence
awareness: it edited the raw marker onto the screen delta-by-delta and
finalized it BEFORE the whole-response filter could run. On any
streaming-capable adapter (Slack, Telegram, Discord, …) users saw a literal
'NO_REPLY' message leak into chat.
Fix (contained in the stream consumer + a shared predicate; no new config,
no platform-specific code):
- gateway/response_filters.py: add is_partial_silence_marker() — the
streaming counterpart to is_intentional_silence_response(), sharing the
same marker set and canonicalization so the two never drift.
- gateway/stream_consumer.py:
- Mid-stream hold-back: defer edits while the accumulated buffer is still a
prefix of a silence marker, so a partial marker never flashes on an
interval tick.
- On stream end (got_done): if the final buffer is exactly a marker, retract
any preview already shown (best-effort delete_message, reusing the
_try_fresh_final cleanup path) and leave the delivery flags False so the
gateway's own filter turns the marker into '' and no fallback send fires.
Substantive prose that merely mentions a marker is still delivered normally.
Tests: tests/gateway/test_stream_consumer_silence.py — predicate truth table
+ end-to-end run() suppression (single-shot + token-by-token), preview
retraction, no-delete-support best-effort, [SILENT] parity, and
prose-passthrough. Prove-fail verified by reverting only the consumer change
(the 4 behavioral tests fail: 'NO_REPLY'/'[SILENT]' leaks).
