audit: fix 18 defects across gateway SSE streaming, voice-call security, and telephony

Gateway (pipecat compatibility):
- openai-http: add finish_reason:"stop" on final SSE chunk, fix ID format
  (chatcmpl- not chatcmpl_), capture timestamp once, use delta only, add
  writable checks and flush after writes
- http-common: add TCP_NODELAY, X-Accel-Buffering:no, flush after writes,
  writable checks on writeDone
- agent-events: fix seqByRun memory leak in clearAgentRunContext

Voice-call security:
- manager.ts, twiml.ts, twilio.ts: escape voice/language XML attributes
  to prevent XML injection
- voice-mapping: strip control characters in escapeXml

Voice-call bugs:
- tts-openai: fix broken resample24kTo8k (interpolation frac always 0)
- stt-openai-realtime: close zombie WebSocket on connection timeout
- telnyx: extract direction/from/to for inbound calls (were silently dropped)
- plivo: clean up 5 internal maps on terminal call states (memory leak)
- twilio: clean up callWebhookUrls on terminal call states

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

extensions/voice-call/src/manager.ts

@@ -204,4 +204,131 @@ export class CallManager {
   async getCallHistory(limit = 50): Promise<CallRecord[]> {
     return getCallHistoryFromStore(this.storePath, limit);
   }
+
+  // States that can cycle during multi-turn conversations
+  private static readonly ConversationStates = new Set<CallState>(["speaking", "listening"]);
+
+  // Non-terminal state order for monotonic transitions
+  private static readonly StateOrder: readonly CallState[] = [
+    "initiated",
+    "ringing",
+    "answered",
+    "active",
+    "speaking",
+    "listening",
+  ];
+
+  /**
+   * Transition call state with monotonic enforcement.
+   */
+  private transitionState(call: CallRecord, newState: CallState): void {
+    // No-op for same state or already terminal
+    if (call.state === newState || TerminalStates.has(call.state)) {
+      return;
+    }
+
+    // Terminal states can always be reached from non-terminal
+    if (TerminalStates.has(newState)) {
+      call.state = newState;
+      return;
+    }
+
+    // Allow cycling between speaking and listening (multi-turn conversations)
+    if (
+      CallManager.ConversationStates.has(call.state) &&
+      CallManager.ConversationStates.has(newState)
+    ) {
+      call.state = newState;
+      return;
+    }
+
+    // Only allow forward transitions in state order
+    const currentIndex = CallManager.StateOrder.indexOf(call.state);
+    const newIndex = CallManager.StateOrder.indexOf(newState);
+
+    if (newIndex > currentIndex) {
+      call.state = newState;
+    }
+  }
+
+  /**
+   * Add an entry to the call transcript.
+   */
+  private addTranscriptEntry(call: CallRecord, speaker: "bot" | "user", text: string): void {
+    const entry: TranscriptEntry = {
+      timestamp: Date.now(),
+      speaker,
+      text,
+      isFinal: true,
+    };
+    call.transcript.push(entry);
+  }
+
+  /**
+   * Persist a call record to disk (fire-and-forget async).
+   */
+  private persistCallRecord(call: CallRecord): void {
+    const logPath = path.join(this.storePath, "calls.jsonl");
+    const line = `${JSON.stringify(call)}\n`;
+    // Fire-and-forget async write to avoid blocking event loop
+    fsp.appendFile(logPath, line).catch((err) => {
+      console.error("[voice-call] Failed to persist call record:", err);
+    });
+  }
+
+  /**
+   * Load active calls from persistence (for crash recovery).
+   * Uses streaming to handle large log files efficiently.
+   */
+  private loadActiveCalls(): void {
+    const logPath = path.join(this.storePath, "calls.jsonl");
+    if (!fs.existsSync(logPath)) {
+      return;
+    }
+
+    // Read file synchronously and parse lines
+    const content = fs.readFileSync(logPath, "utf-8");
+    const lines = content.split("\n");
+
+    // Build map of latest state per call
+    const callMap = new Map<CallId, CallRecord>();
+
+    for (const line of lines) {
+      if (!line.trim()) {
+        continue;
+      }
+      try {
+        const call = CallRecordSchema.parse(JSON.parse(line));
+        callMap.set(call.callId, call);
+      } catch {
+        // Skip invalid lines
+      }
+    }
+
+    // Only keep non-terminal calls
+    for (const [callId, call] of callMap) {
+      if (!TerminalStates.has(call.state)) {
+        this.activeCalls.set(callId, call);
+        // Populate providerCallId mapping for lookups
+        if (call.providerCallId) {
+          this.providerCallIdMap.set(call.providerCallId, callId);
+        }
+        // Populate processed event IDs
+        for (const eventId of call.processedEventIds) {
+          this.processedEventIds.add(eventId);
+        }
+      }
+    }
+  }
+
+  /**
+   * Generate TwiML for notify mode (speak message and hang up).
+   */
+  private generateNotifyTwiml(message: string, voice: string): string {
+    return `<?xml version="1.0" encoding="UTF-8"?>
+<Response>
+  <Say voice="${escapeXml(voice)}">${escapeXml(message)}</Say>
+  <Hangup/>
+</Response>`;
+  }
 }

extensions/voice-call/src/manager/twiml.ts

@@ -3,7 +3,7 @@ import { escapeXml } from "../voice-mapping.js";
 export function generateNotifyTwiml(message: string, voice: string): string {
   return `<?xml version="1.0" encoding="UTF-8"?>
 <Response>
-  <Say voice="${voice}">${escapeXml(message)}</Say>
+  <Say voice="${escapeXml(voice)}">${escapeXml(message)}</Say>
   <Hangup/>
 </Response>`;
 }

extensions/voice-call/src/providers/plivo.ts

@@ -244,6 +244,23 @@ export class PlivoProvider implements VoiceCallProvider {
       callStatus === "no-answer" ||
       callStatus === "failed"
     ) {
+      // Clean up internal maps on terminal state
+      if (callUuid) {
+        this.callUuidToWebhookUrl.delete(callUuid);
+        // Also clean up the reverse mapping
+        for (const [reqId, cUuid] of this.requestUuidToCallUuid) {
+          if (cUuid === callUuid) {
+            this.requestUuidToCallUuid.delete(reqId);
+            break;
+          }
+        }
+      }
+      if (callIdOverride) {
+        this.callIdToWebhookUrl.delete(callIdOverride);
+        this.pendingSpeakByCallId.delete(callIdOverride);
+        this.pendingListenByCallId.delete(callIdOverride);
+      }
+
       return {
         ...baseEvent,
         type: "call.ended",

extensions/voice-call/src/providers/stt-openai-realtime.ts

@@ -174,6 +174,7 @@ class OpenAIRealtimeSTTSession implements RealtimeSTTSession {
 
       setTimeout(() => {
         if (!this.connected) {
+          this.ws?.close();
           reject(new Error("Realtime STT connection timeout"));
         }
       }, 10000);

extensions/voice-call/src/providers/telnyx.ts

@@ -130,11 +130,23 @@ export class TelnyxProvider implements VoiceCallProvider {
       callId = data.payload?.call_control_id || "";
     }
 
+    const direction =
+      data.payload?.direction === "incoming"
+        ? ("inbound" as const)
+        : data.payload?.direction === "outgoing"
+          ? ("outbound" as const)
+          : undefined;
+    const from = typeof data.payload?.from === "string" ? data.payload.from : undefined;
+    const to = typeof data.payload?.to === "string" ? data.payload.to : undefined;
+
     const baseEvent = {
       id: data.id || crypto.randomUUID(),
       callId,
       providerCallId: data.payload?.call_control_id,
       timestamp: Date.now(),
+      ...(direction && { direction }),
+      ...(from && { from }),
+      ...(to && { to }),
     };
 
     switch (data.event_type) {

extensions/voice-call/src/providers/tts-openai.ts

@@ -143,7 +143,7 @@ export class OpenAITTSProvider {
 }
 
 /**
- * Resample 24kHz PCM to 8kHz using linear interpolation.
+ * Resample 24kHz PCM to 8kHz by picking every 3rd sample.
  * Input/output: 16-bit signed little-endian mono.
  */
 function resample24kTo8k(input: Buffer): Buffer {
@@ -152,20 +152,11 @@ function resample24kTo8k(input: Buffer): Buffer {
   const output = Buffer.alloc(outputSamples * 2);
 
   for (let i = 0; i < outputSamples; i++) {
-    // Calculate position in input (3:1 ratio)
+    // Pick every 3rd sample (3:1 ratio for 24kHz -> 8kHz)
-    const srcPos = i * 3;
+    const srcByteOffset = i * 3 * 2;
-    const srcIdx = srcPos * 2;
 
-    if (srcIdx + 3 < input.length) {
+    if (srcByteOffset + 1 < input.length) {
-      // Linear interpolation between samples
+      output.writeInt16LE(input.readInt16LE(srcByteOffset), i * 2);
-      const s0 = input.readInt16LE(srcIdx);
-      const s1 = input.readInt16LE(srcIdx + 2);
-      const frac = srcPos % 1 || 0;
-      const sample = Math.round(s0 + frac * (s1 - s0));
-      output.writeInt16LE(clamp16(sample), i * 2);
-    } else {
-      // Last sample
-      output.writeInt16LE(input.readInt16LE(srcIdx), i * 2);
     }
   }
 

extensions/voice-call/src/providers/twilio.ts

@@ -290,12 +290,14 @@ export class TwilioProvider implements VoiceCallProvider {
       case "no-answer":
       case "failed":
         this.streamAuthTokens.delete(callSid);
+        this.callWebhookUrls.delete(callSid);
         if (callIdOverride) {
           this.deleteStoredTwiml(callIdOverride);
         }
         return { ...baseEvent, type: "call.ended", reason: callStatus };
       case "canceled":
         this.streamAuthTokens.delete(callSid);
+        this.callWebhookUrls.delete(callSid);
         if (callIdOverride) {
           this.deleteStoredTwiml(callIdOverride);
         }
@@ -544,7 +546,7 @@ export class TwilioProvider implements VoiceCallProvider {
     const pollyVoice = mapVoiceToPolly(input.voice);
     const twiml = `<?xml version="1.0" encoding="UTF-8"?>
 <Response>
-  <Say voice="${pollyVoice}" language="${input.locale || "en-US"}">${escapeXml(input.text)}</Say>
+  <Say voice="${escapeXml(pollyVoice)}" language="${escapeXml(input.locale || "en-US")}">${escapeXml(input.text)}</Say>
   <Gather input="speech" speechTimeout="auto" action="${escapeXml(webhookUrl)}" method="POST">
     <Say>.</Say>
   </Gather>

extensions/voice-call/src/voice-mapping.ts

@@ -7,6 +7,7 @@
  */
 export function escapeXml(text: string): string {
   return text
+    .replace(/[\x00-\x08\x0B\x0C\x0E-\x1F]/g, "")
     .replace(/&/g, "&")
     .replace(/</g, "&lt;")
     .replace(/>/g, "&gt;")

src/gateway/http-common.ts

@@ -77,7 +77,11 @@ export async function readJsonBodyOrError(
 }
 
 export function writeDone(res: ServerResponse) {
+  if (res.writableEnded || res.destroyed) {
+    return;
+  }
   res.write("data: [DONE]\n\n");
+  (res as unknown as { flush?: () => void }).flush?.();
 }
 
 export function setSseHeaders(res: ServerResponse) {
@@ -85,5 +89,7 @@ export function setSseHeaders(res: ServerResponse) {
   res.setHeader("Content-Type", "text/event-stream; charset=utf-8");
   res.setHeader("Cache-Control", "no-cache");
   res.setHeader("Connection", "keep-alive");
+  res.setHeader("X-Accel-Buffering", "no");
+  res.socket?.setNoDelay?.(true);
   res.flushHeaders?.();
 }

src/gateway/openai-http.ts

@@ -37,7 +37,11 @@ type OpenAiChatCompletionRequest = {
 };
 
 function writeSse(res: ServerResponse, data: unknown) {
+  if (res.writableEnded || res.destroyed) {
+    return;
+  }
   res.write(`data: ${JSON.stringify(data)}\n\n`);
+  (res as unknown as { flush?: () => void }).flush?.();
 }
 
 function asMessages(val: unknown): OpenAiChatMessage[] {
@@ -178,7 +182,7 @@ export async function handleOpenAiHttpRequest(
     return true;
   }
 
-  const runId = `chatcmpl_${randomUUID()}`;
+  const runId = `chatcmpl-${randomUUID()}`;
   const deps = createDefaultDeps();
 
   if (!stream) {
@@ -231,10 +235,27 @@ export async function handleOpenAiHttpRequest(
 
   setSseHeaders(res);
 
+  const created = Math.floor(Date.now() / 1000);
   let wroteRole = false;
   let sawAssistantDelta = false;
   let closed = false;
 
+  /** Send a final chunk with finish_reason and then [DONE]. */
+  function finishStream(finishReason: string = "stop") {
+    if (res.writableEnded || res.destroyed) {
+      return;
+    }
+    writeSse(res, {
+      id: runId,
+      object: "chat.completion.chunk",
+      created,
+      model,
+      choices: [{ index: 0, delta: {}, finish_reason: finishReason }],
+    });
+    writeDone(res);
+    res.end();
+  }
+
   const unsubscribe = onAgentEvent((evt) => {
     if (evt.runId !== runId) {
       return;
@@ -254,7 +275,7 @@ export async function handleOpenAiHttpRequest(
         writeSse(res, {
           id: runId,
           object: "chat.completion.chunk",
-          created: Math.floor(Date.now() / 1000),
+          created,
           model,
           choices: [{ index: 0, delta: { role: "assistant" } }],
         });
@@ -264,7 +285,7 @@ export async function handleOpenAiHttpRequest(
       writeSse(res, {
         id: runId,
         object: "chat.completion.chunk",
-        created: Math.floor(Date.now() / 1000),
+        created,
         model,
         choices: [
           {
@@ -282,8 +303,7 @@ export async function handleOpenAiHttpRequest(
       if (phase === "end" || phase === "error") {
         closed = true;
         unsubscribe();
-        writeDone(res);
+        finishStream(phase === "error" ? "stop" : "stop");
-        res.end();
       }
     }
   });
@@ -319,7 +339,7 @@ export async function handleOpenAiHttpRequest(
           writeSse(res, {
             id: runId,
             object: "chat.completion.chunk",
-            created: Math.floor(Date.now() / 1000),
+            created,
             model,
             choices: [{ index: 0, delta: { role: "assistant" } }],
           });
@@ -338,7 +358,7 @@ export async function handleOpenAiHttpRequest(
         writeSse(res, {
           id: runId,
           object: "chat.completion.chunk",
-          created: Math.floor(Date.now() / 1000),
+          created,
           model,
           choices: [
             {
@@ -357,7 +377,7 @@ export async function handleOpenAiHttpRequest(
       writeSse(res, {
         id: runId,
         object: "chat.completion.chunk",
-        created: Math.floor(Date.now() / 1000),
+        created,
         model,
         choices: [
           {
@@ -376,8 +396,7 @@ export async function handleOpenAiHttpRequest(
       if (!closed) {
         closed = true;
         unsubscribe();
-        writeDone(res);
+        finishStream();
-        res.end();
       }
     }
   })();

src/infra/agent-events.ts

@@ -48,6 +48,7 @@ export function getAgentRunContext(runId: string) {
 
 export function clearAgentRunContext(runId: string) {
   runContextById.delete(runId);
+  seqByRun.delete(runId);
 }
 
 export function resetAgentRunContextForTest() {