feat: restore voice-call plugin parity

2026-01-12 21:40:22 +00:00
parent 3467b0ba07
commit 42c17adb5e
27 changed files with 6036 additions and 516 deletions
--- a/extensions/voice-call/src/providers/twilio.ts
+++ b/extensions/voice-call/src/providers/twilio.ts
@@ -0,0 +1,537 @@
+import crypto from "node:crypto";
+
+import type { TwilioConfig } from "../config.js";
+import type { MediaStreamHandler } from "../media-stream.js";
+import type {
+  HangupCallInput,
+  InitiateCallInput,
+  InitiateCallResult,
+  NormalizedEvent,
+  PlayTtsInput,
+  ProviderWebhookParseResult,
+  StartListeningInput,
+  StopListeningInput,
+  WebhookContext,
+  WebhookVerificationResult,
+} from "../types.js";
+import { escapeXml, mapVoiceToPolly } from "../voice-mapping.js";
+import { verifyTwilioWebhook } from "../webhook-security.js";
+import type { VoiceCallProvider } from "./base.js";
+import type { OpenAITTSProvider } from "./tts-openai.js";
+import { chunkAudio } from "./tts-openai.js";
+
+/**
+ * Twilio Voice API provider implementation.
+ *
+ * Uses Twilio Programmable Voice API with Media Streams for real-time
+ * bidirectional audio streaming.
+ *
+ * @see https://www.twilio.com/docs/voice
+ * @see https://www.twilio.com/docs/voice/media-streams
+ */
+export interface TwilioProviderOptions {
+  /** Allow ngrok free tier compatibility mode (less secure) */
+  allowNgrokFreeTier?: boolean;
+  /** Override public URL for signature verification */
+  publicUrl?: string;
+  /** Path for media stream WebSocket (e.g., /voice/stream) */
+  streamPath?: string;
+  /** Skip webhook signature verification (development only) */
+  skipVerification?: boolean;
+}
+
+export class TwilioProvider implements VoiceCallProvider {
+  readonly name = "twilio" as const;
+
+  private readonly accountSid: string;
+  private readonly authToken: string;
+  private readonly baseUrl: string;
+  private readonly callWebhookUrls = new Map<string, string>();
+  private readonly options: TwilioProviderOptions;
+
+  /** Current public webhook URL (set when tunnel starts or from config) */
+  private currentPublicUrl: string | null = null;
+
+  /** Optional OpenAI TTS provider for streaming TTS */
+  private ttsProvider: OpenAITTSProvider | null = null;
+
+  /** Optional media stream handler for sending audio */
+  private mediaStreamHandler: MediaStreamHandler | null = null;
+
+  /** Map of call SID to stream SID for media streams */
+  private callStreamMap = new Map<string, string>();
+
+  constructor(config: TwilioConfig, options: TwilioProviderOptions = {}) {
+    if (!config.accountSid) {
+      throw new Error("Twilio Account SID is required");
+    }
+    if (!config.authToken) {
+      throw new Error("Twilio Auth Token is required");
+    }
+
+    this.accountSid = config.accountSid;
+    this.authToken = config.authToken;
+    this.baseUrl = `https://api.twilio.com/2010-04-01/Accounts/${this.accountSid}`;
+    this.options = options;
+
+    if (options.publicUrl) {
+      this.currentPublicUrl = options.publicUrl;
+    }
+  }
+
+  /**
+   * Set the current public webhook URL (called when tunnel starts).
+   */
+  setPublicUrl(url: string): void {
+    this.currentPublicUrl = url;
+  }
+
+  /**
+   * Get the current public webhook URL.
+   */
+  getPublicUrl(): string | null {
+    return this.currentPublicUrl;
+  }
+
+  /**
+   * Set the OpenAI TTS provider for streaming TTS.
+   * When set, playTts will use OpenAI audio via media streams.
+   */
+  setTTSProvider(provider: OpenAITTSProvider): void {
+    this.ttsProvider = provider;
+  }
+
+  /**
+   * Set the media stream handler for sending audio.
+   */
+  setMediaStreamHandler(handler: MediaStreamHandler): void {
+    this.mediaStreamHandler = handler;
+  }
+
+  /**
+   * Register a call's stream SID for audio routing.
+   */
+  registerCallStream(callSid: string, streamSid: string): void {
+    this.callStreamMap.set(callSid, streamSid);
+  }
+
+  /**
+   * Unregister a call's stream SID.
+   */
+  unregisterCallStream(callSid: string): void {
+    this.callStreamMap.delete(callSid);
+  }
+
+  /**
+   * Make an authenticated request to the Twilio API.
+   */
+  private async apiRequest<T = unknown>(
+    endpoint: string,
+    params: Record<string, string>,
+    options?: { allowNotFound?: boolean },
+  ): Promise<T> {
+    const response = await fetch(`${this.baseUrl}${endpoint}`, {
+      method: "POST",
+      headers: {
+        Authorization: `Basic ${Buffer.from(`${this.accountSid}:${this.authToken}`).toString("base64")}`,
+        "Content-Type": "application/x-www-form-urlencoded",
+      },
+      body: new URLSearchParams(params),
+    });
+
+    if (!response.ok) {
+      if (options?.allowNotFound && response.status === 404) {
+        return undefined as T;
+      }
+      const errorText = await response.text();
+      throw new Error(`Twilio API error: ${response.status} ${errorText}`);
+    }
+
+    const text = await response.text();
+    return text ? (JSON.parse(text) as T) : (undefined as T);
+  }
+
+  /**
+   * Verify Twilio webhook signature using HMAC-SHA1.
+   *
+   * Handles reverse proxy scenarios (Tailscale, nginx, ngrok) by reconstructing
+   * the public URL from forwarding headers.
+   *
+   * @see https://www.twilio.com/docs/usage/webhooks/webhooks-security
+   */
+  verifyWebhook(ctx: WebhookContext): WebhookVerificationResult {
+    const result = verifyTwilioWebhook(ctx, this.authToken, {
+      publicUrl: this.currentPublicUrl || undefined,
+      allowNgrokFreeTier: this.options.allowNgrokFreeTier ?? true,
+      skipVerification: this.options.skipVerification,
+    });
+
+    if (!result.ok) {
+      console.warn(`[twilio] Webhook verification failed: ${result.reason}`);
+      if (result.verificationUrl) {
+        console.warn(`[twilio] Verification URL: ${result.verificationUrl}`);
+      }
+    }
+
+    return {
+      ok: result.ok,
+      reason: result.reason,
+    };
+  }
+
+  /**
+   * Parse Twilio webhook event into normalized format.
+   */
+  parseWebhookEvent(ctx: WebhookContext): ProviderWebhookParseResult {
+    try {
+      const params = new URLSearchParams(ctx.rawBody);
+      const callIdFromQuery =
+        typeof ctx.query?.callId === "string" && ctx.query.callId.trim()
+          ? ctx.query.callId.trim()
+          : undefined;
+      const event = this.normalizeEvent(params, callIdFromQuery);
+
+      // For Twilio, we must return TwiML. Most actions are driven by Calls API updates,
+      // so the webhook response is typically a pause to keep the call alive.
+      const twiml = this.generateTwimlResponse(ctx);
+
+      return {
+        events: event ? [event] : [],
+        providerResponseBody: twiml,
+        providerResponseHeaders: { "Content-Type": "application/xml" },
+        statusCode: 200,
+      };
+    } catch {
+      return { events: [], statusCode: 400 };
+    }
+  }
+
+  /**
+   * Parse Twilio direction to normalized format.
+   */
+  private static parseDirection(
+    direction: string | null,
+  ): "inbound" | "outbound" | undefined {
+    if (direction === "inbound") return "inbound";
+    if (direction === "outbound-api" || direction === "outbound-dial")
+      return "outbound";
+    return undefined;
+  }
+
+  /**
+   * Convert Twilio webhook params to normalized event format.
+   */
+  private normalizeEvent(
+    params: URLSearchParams,
+    callIdOverride?: string,
+  ): NormalizedEvent | null {
+    const callSid = params.get("CallSid") || "";
+
+    const baseEvent = {
+      id: crypto.randomUUID(),
+      callId: callIdOverride || callSid,
+      providerCallId: callSid,
+      timestamp: Date.now(),
+      direction: TwilioProvider.parseDirection(params.get("Direction")),
+      from: params.get("From") || undefined,
+      to: params.get("To") || undefined,
+    };
+
+    // Handle speech result (from <Gather>)
+    const speechResult = params.get("SpeechResult");
+    if (speechResult) {
+      return {
+        ...baseEvent,
+        type: "call.speech",
+        transcript: speechResult,
+        isFinal: true,
+        confidence: parseFloat(params.get("Confidence") || "0.9"),
+      };
+    }
+
+    // Handle DTMF
+    const digits = params.get("Digits");
+    if (digits) {
+      return { ...baseEvent, type: "call.dtmf", digits };
+    }
+
+    // Handle call status changes
+    const callStatus = params.get("CallStatus");
+    switch (callStatus) {
+      case "initiated":
+        return { ...baseEvent, type: "call.initiated" };
+      case "ringing":
+        return { ...baseEvent, type: "call.ringing" };
+      case "in-progress":
+        return { ...baseEvent, type: "call.answered" };
+      case "completed":
+      case "busy":
+      case "no-answer":
+      case "failed":
+        return { ...baseEvent, type: "call.ended", reason: callStatus };
+      case "canceled":
+        return { ...baseEvent, type: "call.ended", reason: "hangup-bot" };
+      default:
+        return null;
+    }
+  }
+
+  private static readonly EMPTY_TWIML =
+    '<?xml version="1.0" encoding="UTF-8"?><Response></Response>';
+
+  private static readonly PAUSE_TWIML = `<?xml version="1.0" encoding="UTF-8"?>
+<Response>
+  <Pause length="30"/>
+</Response>`;
+
+  /**
+   * Generate TwiML response for webhook.
+   * When a call is answered, connects to media stream for bidirectional audio.
+   */
+  private generateTwimlResponse(ctx?: WebhookContext): string {
+    if (!ctx) return TwilioProvider.EMPTY_TWIML;
+
+    const params = new URLSearchParams(ctx.rawBody);
+    const callStatus = params.get("CallStatus");
+    const direction = params.get("Direction");
+
+    console.log(
+      `[voice-call] generateTwimlResponse: status=${callStatus} direction=${direction}`,
+    );
+
+    // For inbound calls, answer immediately with stream
+    if (direction === "inbound") {
+      const streamUrl = this.getStreamUrl();
+      return streamUrl
+        ? this.getStreamConnectXml(streamUrl)
+        : TwilioProvider.PAUSE_TWIML;
+    }
+
+    // For outbound calls, only connect to stream when call is in-progress
+    if (callStatus !== "in-progress") {
+      return TwilioProvider.EMPTY_TWIML;
+    }
+
+    const streamUrl = this.getStreamUrl();
+    return streamUrl
+      ? this.getStreamConnectXml(streamUrl)
+      : TwilioProvider.PAUSE_TWIML;
+  }
+
+  /**
+   * Get the WebSocket URL for media streaming.
+   * Derives from the public URL origin + stream path.
+   */
+  private getStreamUrl(): string | null {
+    if (!this.currentPublicUrl || !this.options.streamPath) {
+      return null;
+    }
+
+    // Extract just the origin (host) from the public URL, ignoring any path
+    const url = new URL(this.currentPublicUrl);
+    const origin = url.origin;
+
+    // Convert https:// to wss:// for WebSocket
+    const wsOrigin = origin
+      .replace(/^https:\/\//, "wss://")
+      .replace(/^http:\/\//, "ws://");
+
+    // Append the stream path
+    const path = this.options.streamPath.startsWith("/")
+      ? this.options.streamPath
+      : `/${this.options.streamPath}`;
+
+    return `${wsOrigin}${path}`;
+  }
+
+  /**
+   * Generate TwiML to connect a call to a WebSocket media stream.
+   * This enables bidirectional audio streaming for real-time STT/TTS.
+   *
+   * @param streamUrl - WebSocket URL (wss://...) for the media stream
+   */
+  getStreamConnectXml(streamUrl: string): string {
+    return `<?xml version="1.0" encoding="UTF-8"?>
+<Response>
+  <Connect>
+    <Stream url="${escapeXml(streamUrl)}" />
+  </Connect>
+</Response>`;
+  }
+
+  /**
+   * Initiate an outbound call via Twilio API.
+   * If inlineTwiml is provided, uses that directly (for notify mode).
+   * Otherwise, uses webhook URL for dynamic TwiML.
+   */
+  async initiateCall(input: InitiateCallInput): Promise<InitiateCallResult> {
+    const url = new URL(input.webhookUrl);
+    url.searchParams.set("callId", input.callId);
+
+    // Build request params
+    const params: Record<string, string> = {
+      To: input.to,
+      From: input.from,
+      StatusCallback: url.toString(),
+      StatusCallbackEvent: "initiated ringing answered completed",
+      Timeout: "30",
+    };
+
+    // Use inline TwiML for notify mode (simpler, no webhook needed)
+    if (input.inlineTwiml) {
+      params.Twiml = input.inlineTwiml;
+    } else {
+      params.Url = url.toString();
+    }
+
+    const result = await this.apiRequest<TwilioCallResponse>(
+      "/Calls.json",
+      params,
+    );
+
+    this.callWebhookUrls.set(result.sid, url.toString());
+
+    return {
+      providerCallId: result.sid,
+      status: result.status === "queued" ? "queued" : "initiated",
+    };
+  }
+
+  /**
+   * Hang up a call via Twilio API.
+   */
+  async hangupCall(input: HangupCallInput): Promise<void> {
+    this.callWebhookUrls.delete(input.providerCallId);
+
+    await this.apiRequest(
+      `/Calls/${input.providerCallId}.json`,
+      { Status: "completed" },
+      { allowNotFound: true },
+    );
+  }
+
+  /**
+   * Play TTS audio via Twilio.
+   *
+   * Two modes:
+   * 1. OpenAI TTS + Media Streams: If TTS provider and media stream are available,
+   *    generates audio via OpenAI and streams it through WebSocket (preferred).
+   * 2. TwiML <Say>: Falls back to Twilio's native TTS with Polly voices.
+   *    Note: This may not work on all Twilio accounts.
+   */
+  async playTts(input: PlayTtsInput): Promise<void> {
+    // Try OpenAI TTS via media stream first (if configured)
+    const streamSid = this.callStreamMap.get(input.providerCallId);
+    if (this.ttsProvider && this.mediaStreamHandler && streamSid) {
+      try {
+        await this.playTtsViaStream(input.text, streamSid);
+        return;
+      } catch (err) {
+        console.warn(
+          `[voice-call] OpenAI TTS failed, falling back to Twilio <Say>:`,
+          err instanceof Error ? err.message : err,
+        );
+        // Fall through to TwiML <Say> fallback
+      }
+    }
+
+    // Fall back to TwiML <Say> (may not work on all accounts)
+    const webhookUrl = this.callWebhookUrls.get(input.providerCallId);
+    if (!webhookUrl) {
+      throw new Error(
+        "Missing webhook URL for this call (provider state not initialized)",
+      );
+    }
+
+    console.warn(
+      "[voice-call] Using TwiML <Say> fallback - OpenAI TTS not configured or media stream not active",
+    );
+
+    const pollyVoice = mapVoiceToPolly(input.voice);
+    const twiml = `<?xml version="1.0" encoding="UTF-8"?>
+<Response>
+  <Say voice="${pollyVoice}" language="${input.locale || "en-US"}">${escapeXml(input.text)}</Say>
+  <Gather input="speech" speechTimeout="auto" action="${escapeXml(webhookUrl)}" method="POST">
+    <Say>.</Say>
+  </Gather>
+</Response>`;
+
+    await this.apiRequest(`/Calls/${input.providerCallId}.json`, {
+      Twiml: twiml,
+    });
+  }
+
+  /**
+   * Play TTS via OpenAI and Twilio Media Streams.
+   * Generates audio with OpenAI TTS, converts to mu-law, and streams via WebSocket.
+   * Uses a jitter buffer to smooth out timing variations.
+   */
+  private async playTtsViaStream(
+    text: string,
+    streamSid: string,
+  ): Promise<void> {
+    if (!this.ttsProvider || !this.mediaStreamHandler) {
+      throw new Error("TTS provider and media stream handler required");
+    }
+
+    // Generate audio with OpenAI TTS (returns mu-law at 8kHz)
+    const muLawAudio = await this.ttsProvider.synthesizeForTwilio(text);
+
+    // Stream audio in 20ms chunks (160 bytes at 8kHz mu-law)
+    const CHUNK_SIZE = 160;
+    const CHUNK_DELAY_MS = 20;
+
+    for (const chunk of chunkAudio(muLawAudio, CHUNK_SIZE)) {
+      this.mediaStreamHandler.sendAudio(streamSid, chunk);
+
+      // Pace the audio to match real-time playback
+      await new Promise((resolve) => setTimeout(resolve, CHUNK_DELAY_MS));
+    }
+
+    // Send a mark to track when audio finishes
+    this.mediaStreamHandler.sendMark(streamSid, `tts-${Date.now()}`);
+  }
+
+  /**
+   * Start listening for speech via Twilio <Gather>.
+   */
+  async startListening(input: StartListeningInput): Promise<void> {
+    const webhookUrl = this.callWebhookUrls.get(input.providerCallId);
+    if (!webhookUrl) {
+      throw new Error(
+        "Missing webhook URL for this call (provider state not initialized)",
+      );
+    }
+
+    const twiml = `<?xml version="1.0" encoding="UTF-8"?>
+<Response>
+  <Gather input="speech" speechTimeout="auto" language="${input.language || "en-US"}" action="${escapeXml(webhookUrl)}" method="POST">
+  </Gather>
+</Response>`;
+
+    await this.apiRequest(`/Calls/${input.providerCallId}.json`, {
+      Twiml: twiml,
+    });
+  }
+
+  /**
+   * Stop listening - for Twilio this is a no-op as <Gather> auto-ends.
+   */
+  async stopListening(_input: StopListeningInput): Promise<void> {
+    // Twilio's <Gather> automatically stops on speech end
+    // No explicit action needed
+  }
+}
+
+// -----------------------------------------------------------------------------
+// Twilio-specific types
+// -----------------------------------------------------------------------------
+
+interface TwilioCallResponse {
+  sid: string;
+  status: string;
+  direction: string;
+  from: string;
+  to: string;
+  uri: string;
+}