From 18ecdfa154c0b1c3f49e1af23b6ad8ef439d75e2 Mon Sep 17 00:00:00 2001
From: Chase Fagen <fagenchase@gmail.com>
Date: Fri, 26 Jun 2026 11:27:19 +0100
Subject: [PATCH] Add AssemblyAI inactivity timeout option

---
 .changeset/assemblyai-inactivity-timeout.md |  5 +++
 plugins/assemblyai/src/stt.test.ts          | 50 +++++++++++++++++++++
 plugins/assemblyai/src/stt.ts               |  6 +++
 3 files changed, 61 insertions(+)
 create mode 100644 .changeset/assemblyai-inactivity-timeout.md

diff --git a/.changeset/assemblyai-inactivity-timeout.md b/.changeset/assemblyai-inactivity-timeout.md
new file mode 100644
index 000000000..059d30c28
--- /dev/null
+++ b/.changeset/assemblyai-inactivity-timeout.md
@@ -0,0 +1,5 @@
+---
+'@livekit/agents-plugin-assemblyai': patch
+---
+
+Add AssemblyAI streaming `inactivityTimeout` support.
diff --git a/plugins/assemblyai/src/stt.test.ts b/plugins/assemblyai/src/stt.test.ts
index 7d8dc785c..f4872caf5 100644
--- a/plugins/assemblyai/src/stt.test.ts
+++ b/plugins/assemblyai/src/stt.test.ts
@@ -3,9 +3,33 @@
 // SPDX-License-Identifier: Apache-2.0
 import { VAD } from '@livekit/agents-plugin-silero';
 import { stt } from '@livekit/agents-plugins-test';
+import { once } from 'node:events';
+import type { AddressInfo } from 'node:net';
 import { describe, expect, it } from 'vitest';
+import { WebSocketServer } from 'ws';
 import { STT } from './stt.js';
 
+async function startWebSocketServer() {
+  const wss = new WebSocketServer({ host: '127.0.0.1', port: 0 });
+  await once(wss, 'listening');
+  const address = wss.address() as AddressInfo;
+  return { wss, baseUrl: `ws://127.0.0.1:${address.port}` };
+}
+
+async function closeWebSocketServer(wss: WebSocketServer): Promise<void> {
+  for (const client of wss.clients) client.close();
+  await new Promise<void>((resolve) => wss.close(() => resolve()));
+}
+
+async function waitUntil(predicate: () => boolean, timeoutMs = 1000): Promise<void> {
+  const startedAt = Date.now();
+  while (Date.now() - startedAt < timeoutMs) {
+    if (predicate()) return;
+    await new Promise((resolve) => setTimeout(resolve, 10));
+  }
+  throw new Error('timed out waiting for condition');
+}
+
 describe('AssemblyAI options', () => {
   it('accepts u3-rt-pro-beta-1', () => {
     const stt = new STT({ apiKey: 'test-key', speechModel: 'u3-rt-pro-beta-1' });
@@ -47,6 +71,32 @@ describe('AssemblyAI options', () => {
         }),
     ).toThrow(/previousContextNTurns/);
   });
+
+  it('forwards inactivity timeout to the streaming query', async () => {
+    const { wss, baseUrl } = await startWebSocketServer();
+    let requestUrl = '';
+
+    wss.on('connection', (_ws, req) => {
+      requestUrl = req.url ?? '';
+    });
+
+    try {
+      const stream = new STT({
+        apiKey: 'test-key',
+        baseUrl,
+        inactivityTimeout: 45,
+      }).stream();
+
+      await waitUntil(() => requestUrl !== '');
+      stream.close();
+
+      const url = new URL(`ws://127.0.0.1${requestUrl}`);
+      expect(url.pathname).toBe('/v3/ws');
+      expect(url.searchParams.get('inactivity_timeout')).toBe('45');
+    } finally {
+      await closeWebSocketServer(wss);
+    }
+  });
 });
 
 const hasAssemblyAIApiKey = Boolean(process.env.ASSEMBLYAI_API_KEY);
diff --git a/plugins/assemblyai/src/stt.ts b/plugins/assemblyai/src/stt.ts
index b504ac59f..dca019579 100644
--- a/plugins/assemblyai/src/stt.ts
+++ b/plugins/assemblyai/src/stt.ts
@@ -65,6 +65,11 @@ export interface STTOptions {
   encoding: STTEncoding;
   speechModel: STTModels;
   languageDetection?: boolean;
+  /**
+   * Session inactivity timeout in seconds. AssemblyAI accepts integer values
+   * from 5 to 3600; when unset, no inactivity timeout is applied.
+   */
+  inactivityTimeout?: number;
   endOfTurnConfidenceThreshold?: number;
   /** Minimum silence (ms) before a confident end-of-turn is finalized. */
   minTurnSilence?: number;
@@ -322,6 +327,7 @@ export class SpeechStream extends stt.SpeechStream {
           ? JSON.stringify(this.#opts.keytermsPrompt)
           : undefined,
       language_detection: languageDetection,
+      inactivity_timeout: this.#opts.inactivityTimeout,
       prompt: this.#opts.prompt,
       agent_context: this.#opts.agentContext,
       previous_context_n_turns: this.#opts.previousContextNTurns,