fix(mixed): raise CSRC_INACTIVE_MS 400 → 800 ms, measured on live Teams

core/meetings/modules/mixed-capture-core/src/csrc-poll.test.ts

@@ -81,11 +81,14 @@ const receiver = (sources: () => ContributingSourceLike[]) => ({
   t += 200; poll.poll();
   check('inside the inactivity window a stale entry is NOT yet a deactivation',
     out.length === 1, JSON.stringify(out));
-  t += 300; poll.poll();   // 500ms > 400ms default
+  t += 550; poll.poll();   // 750ms staleness — just inside the 800ms window
+  check('just inside the window the entry is STILL held open (the boundary, not the middle)',
+    out.length === 1, JSON.stringify(out));
+  t += 100; poll.poll();   // 850ms > 800ms default
   check('past inactiveMs the deactivation is SYNTHESIZED (the transport never sends this edge)',
     out.length === 2 && out[1].active === false && out[1].csrc === 7 && out[1].tMs === t,
     JSON.stringify(out));
-  check('the default inactivity window is 400ms', CSRC_INACTIVE_MS === 400);
+  check('the default inactivity window is 800ms', CSRC_INACTIVE_MS === 800);
 
   // Speaking again is a NEW activation — turns are edges, not a level.
   speaking = true; lastSpoke = t; poll.poll();
@@ -117,7 +120,7 @@ const receiver = (sources: () => ContributingSourceLike[]) => ({
     JSON.stringify(out));
   check('health counts both as active', poll.health().active === 2, JSON.stringify(poll.health()));
   live.delete(11);
-  t += 500; poll.poll();
+  t += 900; poll.poll();
   check('only the source that went quiet deactivates; the other stays open',
     out.length === 3 && out[2].csrc === 11 && out[2].active === false && poll.health().active === 1,
     JSON.stringify(out));

core/meetings/modules/mixed-capture-core/src/csrc-poll.ts

@@ -112,7 +112,7 @@ export interface CsrcPollOptions {
   receivers?: () => CsrcReceiverLike[];
   /** Poll cadence in ms. Default 100 — the granularity the transport itself updates at. */
   pollMs?: number;
-  /** How long a source stays active after its last observed contribution. Default 400 ms. */
+  /** How long a source stays active after its last observed contribution. Default 800 ms. */
   inactiveMs?: number;
   /** Epoch-ms clock (injectable for tests). */
   now?: () => number;
@@ -133,8 +133,13 @@ export interface CsrcPoll {
 
 /** The transport updates roughly per packet; 100 ms is one packet-train, not an arbitrary tick. */
 export const CSRC_POLL_MS = 100;
-/** Chosen to span a packet gap (jitter, DTX, a brief pause) without holding a finished turn open. */
-export const CSRC_INACTIVE_MS = 400;
+/** Chosen to span a packet gap (jitter, DTX, a brief pause) without holding a finished turn open.
+ *  Measured on a live Microsoft Teams meeting (2026-08-20): replaying this transition logic over a
+ *  599-sample tape of a 6 s speech / 7 s silence cycle yields 10 deactivations at 400 ms —
+ *  fragmenting one speech phase into segments as short as 0.1 s — against 7 at 800 ms, where the
+ *  reconstructed segments match the fixture's real structure. Teams' mixer pauses inside a turn
+ *  for longer than one packet-train, so 400 ms closes turns that are still open. */
+export const CSRC_INACTIVE_MS = 800;
 /** Beyond this, a timestamp is not the clock we think it is. Mirrors the bridge's hint guard. */
 const MAX_CLOCK_SKEW_MS = 10 * 60 * 1000;
 

core/meetings/modules/mixed-pipeline/src/chunked-transcriber.ts

@@ -651,8 +651,8 @@ export class ChunkedTranscriber {
         if (!mine()) return;
         if (this.turn && ev.tracks) this.turn.spanTracks = ev.tracks;
         // A segmenter's speech-end lands a little early and needs a trailing STT pad; a transport
-        // deactivation already carries the sensor's own 400ms inactivity window, so padding it
-        // again would only feed Whisper more silence.
+        // deactivation already carries the sensor's own inactivity window (CSRC_INACTIVE_MS), so
+        // padding it again would only feed Whisper more silence.
         this.closeTurn(ev.t1, ev.reason === 'silence' ? SILENCE_CLOSE_CONTEXT_MS : 0);
       },
     };

core/meetings/modules/mixed-pipeline/src/turn-source.ts

@@ -203,9 +203,11 @@ const envNumber = (name: string, fallback: number): number => {
   return Number.isFinite(n) && n > 0 ? n : fallback;
 };
 
-/** How long a source may go quiet before its turn is closed. The sensor already waits 400ms before
- *  declaring a deactivation, so this is the SECOND grace: it spans a breath, a DTX gap, a dropped
- *  packet train. Too small shatters a sentence into turns; too large merges a real handoff. */
+/** How long a source may go quiet before its turn is closed. The sensor already waits
+ *  CSRC_INACTIVE_MS (800 ms, measured on live Teams) before declaring a deactivation, so this is
+ *  the SECOND grace: it spans a breath, a DTX gap, a dropped packet train. Too small shatters a
+ *  sentence into turns; too large merges a real handoff. Combined worst-case close latency is the
+ *  sum of both graces (~1.4 s at the defaults). */
 export const CSRC_HYSTERESIS_MS = envNumber('VEXA_CSRC_HYSTERESIS_MS', 600);
 /** Energetic audio this long with NOT ONE transition ⇒ the transport stopped talking to us while
  *  the meeting continued. Measured in audio time, on frames that carry energy, so an honestly

core/meetings/services/bot/src/csrc-capture.boundary.test.ts

@@ -139,7 +139,7 @@ async function main(): Promise<void> {
     await page.evaluate('window.__fixtureSpeakingSince = performance.now();');
     await sleep(400);
     await page.evaluate('window.__fixtureSpeakingSince = null;');
-    await sleep(900);                                    // > the 400ms inactivity window
+    await sleep(1300);                                   // > the 800ms inactivity window, with real-clock margin
     await stop();
     await recorder.close();