voice-call: harden closed-loop turn loop and transcript routing (#19140)

Merged via /review-pr -> /prepare-pr -> /merge-pr.

Prepared head SHA: 14a3edb005
Co-authored-by: mbelinky <132747814+mbelinky@users.noreply.github.com>
Co-authored-by: mbelinky <132747814+mbelinky@users.noreply.github.com>
Reviewed-by: @mbelinky

extensions/voice-call/src/cli.ts

@@ -41,6 +41,40 @@ function resolveDefaultStorePath(config: VoiceCallConfig): string {
   return path.join(base, "calls.jsonl");
 }
 
+function percentile(values: number[], p: number): number {
+  if (values.length === 0) {
+    return 0;
+  }
+  const sorted = [...values].sort((a, b) => a - b);
+  const idx = Math.min(sorted.length - 1, Math.max(0, Math.ceil((p / 100) * sorted.length) - 1));
+  return sorted[idx] ?? 0;
+}
+
+function summarizeSeries(values: number[]): {
+  count: number;
+  minMs: number;
+  maxMs: number;
+  avgMs: number;
+  p50Ms: number;
+  p95Ms: number;
+} {
+  if (values.length === 0) {
+    return { count: 0, minMs: 0, maxMs: 0, avgMs: 0, p50Ms: 0, p95Ms: 0 };
+  }
+
+  const minMs = values.reduce((min, value) => (value < min ? value : min), Number.POSITIVE_INFINITY);
+  const maxMs = values.reduce((max, value) => (value > max ? value : max), Number.NEGATIVE_INFINITY);
+  const avgMs = values.reduce((sum, value) => sum + value, 0) / values.length;
+  return {
+    count: values.length,
+    minMs,
+    maxMs,
+    avgMs,
+    p50Ms: percentile(values, 50),
+    p95Ms: percentile(values, 95),
+  };
+}
+
 export function registerVoiceCallCli(params: {
   program: Command;
   config: VoiceCallConfig;
@@ -216,6 +250,57 @@ export function registerVoiceCallCli(params: {
       }
     });
 
+  root
+    .command("latency")
+    .description("Summarize turn latency metrics from voice-call JSONL logs")
+    .option("--file <path>", "Path to calls.jsonl", resolveDefaultStorePath(config))
+    .option("--last <n>", "Analyze last N records", "200")
+    .action(async (options: { file: string; last?: string }) => {
+      const file = options.file;
+      const last = Math.max(1, Number(options.last ?? 200));
+
+      if (!fs.existsSync(file)) {
+        throw new Error("No log file at " + file);
+      }
+
+      const content = fs.readFileSync(file, "utf8");
+      const lines = content.split("\n").filter(Boolean).slice(-last);
+
+      const turnLatencyMs: number[] = [];
+      const listenWaitMs: number[] = [];
+
+      for (const line of lines) {
+        try {
+          const parsed = JSON.parse(line) as {
+            metadata?: { lastTurnLatencyMs?: unknown; lastTurnListenWaitMs?: unknown };
+          };
+          const latency = parsed.metadata?.lastTurnLatencyMs;
+          const listenWait = parsed.metadata?.lastTurnListenWaitMs;
+          if (typeof latency === "number" && Number.isFinite(latency)) {
+            turnLatencyMs.push(latency);
+          }
+          if (typeof listenWait === "number" && Number.isFinite(listenWait)) {
+            listenWaitMs.push(listenWait);
+          }
+        } catch {
+          // ignore malformed JSON lines
+        }
+      }
+
+      // eslint-disable-next-line no-console
+      console.log(
+        JSON.stringify(
+          {
+            recordsScanned: lines.length,
+            turnLatency: summarizeSeries(turnLatencyMs),
+            listenWait: summarizeSeries(listenWaitMs),
+          },
+          null,
+          2,
+        ),
+      );
+    });
+
   root
     .command("expose")
     .description("Enable/disable Tailscale serve/funnel for the webhook")