feat(pipeline): pause-and-resume false-interruption handling (TypeScript)

TypeScript port of 3877814 — exact parity with the Python semantics,
defaults, and events (camelCase ↔ snake_case naming):

Opt-in agent.bargeInMode: 'pause_resume' (default 'cancel' keeps today's
behaviour byte-identical). LiveKit-style state machine on VAD
speech_start while the agent speaks:

- PAUSE: gate the sentence/audio send loops on outputPaused and
  sendClear the carrier so queued audio stops within a frame. The LLM
  stream and TTS provider stream stay alive: sentences buffer as text
  (capped at 32) and synthesized audio queues into per-sentence
  retention entries (capped at ~15 s of playout; overflow while paused
  degrades to a full cancel, overflow while speaking releases retention
  for the turn). Mic audio flows to STT while paused and the inbound
  ring is flushed so the confirm window can actually hear the user.
- KILL: a committed final transcript (non-echo, non-hallucination,
  non-duplicate — the existing handleBargeIn/commitTranscript filter
  family) within bargeInConfirmMs (default 1500 ms) runs the existing
  runBargeInCancel path and discards the paused buffers. The overlap
  window anchored at pause time is preserved so detection_delay
  measures VAD-T1 -> confirm-T2.
- RESUME: window expires with no confirming transcript -> re-send the
  cleared-but-unheard tail from retained audio at SENTENCE granularity
  (first sentence not fully played, derived from the #164
  playbackBufferedUntil cursor + heard-prefix segments; the
  partially-played sentence replays from its start) without re-billing
  TTS, then release the buffered sentences through the normal synth
  path. Recorded as a false interruption via recordOverlapEnd(false) —
  the backchannel counter, never an interruption — plus a
  'false_interruption' event ({ resumedSentences }).

The playback bookkeeping is frozen at the heard offset on pause so a
kill still rewrites history to the heard prefix; on resume the replay
re-stamps segments so later barge-ins stay accurate. Turn bodies wait
out an in-flight pause decision before ending — completes the
predecessor's in-progress port by bounding awaitPauseDecision (confirm
window + 5 s fail-open margin, mirroring Python's
_await_pause_decision) so a teardown race can never strand the
dispatch loop.

Tests mirror tests/unit/test_barge_in_pause_resume.py: pause gates
without cancelling, paused buffering + overflow degradation, resume
tail replay + false-interruption metrics/event, kill filters
(final-only / hallucination / duplicate / frozen-prefix history
rewrite), legacy cancel mode untouched, config-off defaults,
streaming-loop integration (resume, kill, stream-ends-paused), and
teardown mid-pause.

https://claude.ai/code/session_01BJxPoE8v57ck3EDfeZCpo4

Author: claude

libraries/typescript/src/observability/event-bus.ts

@@ -25,7 +25,11 @@ export type PatterEventType =
   | 'transcript_final'
   | 'llm_chunk'
   | 'tts_chunk'
-  | 'tool_call_started';
+  | 'tool_call_started'
+  // Pause-and-resume (bargeInMode: 'pause_resume'): a pause that no
+  // transcript confirmed resumed from the unheard tail. Payload:
+  // ``{ resumedSentences: number }``. Mirrors the Python emit.
+  | 'false_interruption';
 
 type Listener<T = unknown> = (payload: T) => void | Promise<void>;