Function startSessionActivity

src/utils/sessionActivity.ts:92–115

(reason: SessionActivityReason)

 * is registered, start a periodic heartbeat timer.
 */
export function startSessionActivity(reason: SessionActivityReason): void {
  refcount++
  activeReasons.set(reason, (activeReasons.get(reason) ?? 0) + 1)
  if (refcount === 1) {
    oldestActivityStartedAt = Date.now()
    if (activityCallback !== null && heartbeatTimer === null) {
      startHeartbeatTimer()
    }
  }
  if (!cleanupRegistered) {
    cleanupRegistered = true
    registerCleanup(async () => {
      logForDiagnosticsNoPII('info', 'session_activity_at_shutdown', {
        refcount,
        active: Object.fromEntries(activeReasons),
        // Only meaningful while work is in-flight; stale otherwise.
        oldest_activity_ms:
          refcount > 0 && oldestActivityStartedAt !== null
            ? Date.now() - oldestActivityStartedAt
            : null,
      })
    })
  }
}

/**
 * Decrement the activity refcount. When it reaches 0, stop the heartbeat timer