fix: harden voice-call webhooks (#1213) (thanks @andrew-kurin)

CHANGELOG.md

@@ -20,6 +20,7 @@ Docs: https://docs.clawd.bot
 - TUI: show generic empty-state text for searchable pickers. (#1201) — thanks @vignesh07.
 - Doctor: canonicalize legacy session keys in session stores to prevent stale metadata. (#1169)
 - CLI: centralize CLI command registration to keep fast-path routing and program wiring in sync. (#1207) — thanks @gumadeiras.
+- Voice call: keep Twilio notify callbacks out of streaming paths, normalize Tailscale serve paths, and honor ASCII signature ordering. (#1213) — thanks @andrew-kurin.
 
 ## 2026.1.18-5
 

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

@@ -64,17 +64,21 @@ export class TwilioProvider implements VoiceCallProvider {
 
   /** Storage for TwiML content (for notify mode with URL-based TwiML) */
   private readonly twimlStorage = new Map<string, string>();
-  /** Track notify-mode calls to avoid streaming on follow-up callbacks */
+  /** Track notify-mode calls to avoid streaming on follow-up callbacks. */
   private readonly notifyCalls = new Set<string>();
 
   /**
    * Delete stored TwiML for a given `callId`.
    *
    * We keep TwiML in-memory only long enough to satisfy the initial Twilio
-   * webhook request (notify mode). Subsequent webhooks should not reuse it.
+   * webhook request (notify mode). The notify guard is cleared separately.
    */
   private deleteStoredTwiml(callId: string): void {
     this.twimlStorage.delete(callId);
+  }
+
+  private clearNotifyState(callId: string): void {
+    this.twimlStorage.delete(callId);
     this.notifyCalls.delete(callId);
   }
 
@@ -90,7 +94,7 @@ export class TwilioProvider implements VoiceCallProvider {
     const callIdMatch = webhookUrl.match(/callId=([^&]+)/);
     if (!callIdMatch) return;
 
-    this.deleteStoredTwiml(callIdMatch[1]);
+    this.clearNotifyState(callIdMatch[1]);
   }
 
   constructor(config: TwilioConfig, options: TwilioProviderOptions = {}) {
@@ -260,12 +264,12 @@ export class TwilioProvider implements VoiceCallProvider {
       case "no-answer":
       case "failed":
         if (callIdOverride) {
-          this.deleteStoredTwiml(callIdOverride);
+          this.clearNotifyState(callIdOverride);
         }
         return { ...baseEvent, type: "call.ended", reason: callStatus };
       case "canceled":
         if (callIdOverride) {
-          this.deleteStoredTwiml(callIdOverride);
+          this.clearNotifyState(callIdOverride);
         }
         return { ...baseEvent, type: "call.ended", reason: "hangup-bot" };
       default:
@@ -399,6 +403,7 @@ export class TwilioProvider implements VoiceCallProvider {
     // We now serve it from the webhook endpoint instead of sending inline
     if (input.inlineTwiml) {
       this.twimlStorage.set(input.callId, input.inlineTwiml);
+      // Keep notify-mode calls out of streaming TwiML for any follow-up callbacks.
       this.notifyCalls.add(input.callId);
     }
 

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

@@ -0,0 +1,39 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+import { twilioApiRequest } from "./api.js";
+
+describe("twilioApiRequest", () => {
+  afterEach(() => {
+    vi.unstubAllGlobals();
+    vi.restoreAllMocks();
+  });
+
+  it("encodes array params as repeated form fields", async () => {
+    const fetchMock = vi.fn().mockResolvedValue({
+      ok: true,
+      text: async () => "",
+    });
+
+    vi.stubGlobal("fetch", fetchMock as unknown as typeof fetch);
+
+    await twilioApiRequest({
+      baseUrl: "https://api.example.com",
+      accountSid: "AC123",
+      authToken: "token",
+      endpoint: "/Calls.json",
+      body: {
+        To: "+15555550123",
+        StatusCallbackEvent: ["initiated", "completed"],
+      },
+    });
+
+    const [, init] = fetchMock.mock.calls[0] ?? [];
+    const body = init?.body as URLSearchParams | undefined;
+
+    expect(body?.getAll("StatusCallbackEvent")).toEqual([
+      "initiated",
+      "completed",
+    ]);
+    expect(body?.get("To")).toBe("+15555550123");
+  });
+});

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

@@ -29,6 +29,7 @@ export async function twilioApiRequest<T = unknown>(params: {
       Authorization: `Basic ${Buffer.from(`${params.accountSid}:${params.authToken}`).toString("base64")}`,
       "Content-Type": "application/x-www-form-urlencoded",
     },
+    // URL-encoded body required by Twilio, with repeated keys for arrays.
     body: bodyParams,
   });
 

extensions/voice-call/src/tunnel.ts

@@ -231,7 +231,8 @@ export async function startTailscaleTunnel(config: {
   }
 
   const path = config.path.startsWith("/") ? config.path : `/${config.path}`;
-  const localUrl = `http://127.0.0.1:${config.port}${path}`;
+  // --set-path already mounts the path; keep the target base URL to avoid /path/path.
+  const localUrl = `http://127.0.0.1:${config.port}`;
 
   return new Promise((resolve, reject) => {
     const proc = spawn(

extensions/voice-call/src/webhook-security.test.ts

@@ -79,7 +79,7 @@ function twilioSignature(params: {
   let dataToSign = params.url;
   const sortedParams = Array.from(
     new URLSearchParams(params.postBody).entries(),
-  ).sort((a, b) => a[0].localeCompare(b[0]));
+  ).sort((a, b) => (a[0] < b[0] ? -1 : a[0] > b[0] ? 1 : 0));
 
   for (const [key, value] of sortedParams) {
     dataToSign += key + value;
@@ -205,4 +205,33 @@ describe("verifyTwilioWebhook", () => {
 
     expect(result.ok).toBe(true);
   });
+
+  it("sorts params using ASCII order", () => {
+    const authToken = "test-auth-token";
+    const publicUrl = "https://example.com/voice/webhook";
+    const postBody = "Z=first&a=second";
+
+    const signature = twilioSignature({
+      authToken,
+      url: publicUrl,
+      postBody,
+    });
+
+    const result = verifyTwilioWebhook(
+      {
+        headers: {
+          host: "example.com",
+          "x-forwarded-proto": "https",
+          "x-twilio-signature": signature,
+        },
+        rawBody: postBody,
+        url: "http://local/voice/webhook",
+        method: "POST",
+      },
+      authToken,
+      { publicUrl },
+    );
+
+    expect(result.ok).toBe(true);
+  });
 });

extensions/voice-call/src/webhook-security.ts

@@ -23,7 +23,7 @@ export function validateTwilioSignature(
   // Build the string to sign: URL + sorted params (key+value pairs)
   let dataToSign = url;
 
-  // Sort params alphabetically and append key+value
+  // Sort params by ASCII order (Twilio spec) and append key+value.
   const sortedParams = Array.from(params.entries()).sort((a, b) =>
     a[0] < b[0] ? -1 : a[0] > b[0] ? 1 : 0,
   );

src/agents/system-prompt.ts

@@ -553,7 +553,7 @@ export function buildAgentSystemPrompt(params: {
 }
 
 export function buildRuntimeLine(
-  runtimeInfo: {
+  runtimeInfo?: {
     agentId?: string;
     host?: string;
     os?: string;