Merge branch 'main' into fix/fd_1828

lib/utils/tts-streaming-buffer.js

@@ -220,7 +220,8 @@ class TtsStreamingBuffer extends Emitter {
           this.queue.shift();
         }
         // Immediately send all accumulated text (ignoring sentence boundaries).
-        if (flushText.length > 0) {
+        // Skip sending if flushText is only whitespace.
+        if (flushText.length > 0 && !isWhitespace(flushText)) {
           const modifiedFlushText = flushText.replace(/\n\n/g, '\n \n');
           try {
             await this._api(this.ep, [this.ep.uuid, 'send', modifiedFlushText]);

test/index.js

@@ -4,6 +4,7 @@ require('./ws-requestor-unit-test');
 require('./http-requestor-retry-test');
 require('./http-requestor-unit-test');
 require('./unit-tests');
+require('./tts-streaming-buffer-test');
 require('./docker_start');
 require('./create-test-db');
 require('./account-validation-tests');

test/tts-streaming-buffer-test.js

@@ -0,0 +1,177 @@
+const test = require('tape');
+const sinon = require('sinon');
+
+const noop = () => {};
+const logger = {
+  error: noop,
+  info: noop,
+  debug: noop
+};
+
+const {
+  TtsStreamingConnectionStatus
+} = require('../lib/utils/constants.json');
+
+const TtsStreamingBuffer = require('../lib/utils/tts-streaming-buffer');
+
+// Helper to create a mock CallSession
+function createMockCs(options = {}) {
+  const mockEp = {
+    uuid: 'test-uuid-1234',
+    api: sinon.stub().resolves({ body: '+OK' }),
+    addCustomEventListener: sinon.stub(),
+    removeCustomEventListener: sinon.stub()
+  };
+
+  return {
+    logger,
+    ep: mockEp,
+    isTtsStreamOpen: options.isTtsStreamOpen !== undefined ? options.isTtsStreamOpen : true,
+    getTsStreamingVendor: () => options.vendor || 'deepgram'
+  };
+}
+
+/**
+ * BUG REPRODUCTION TEST
+ *
+ * This test reproduces the exact issue from production logs:
+ * {
+ *   "args": ["uuid", "send", " "],
+ *   "msg": "Error calling uuid_deepgram_tts_streaming: -USAGE: <uuid> connect|send|clear|close [tokens]"
+ * }
+ *
+ * Root cause: When multiple flushes are queued while connecting, and a space token
+ * gets buffered between flushes, Phase 1 of _feedQueue sends that space to the TTS vendor.
+ *
+ * Sequence:
+ * 1. bufferTokens('Hello.') while connecting
+ * 2. flush() while connecting
+ * 3. bufferTokens(' ') while connecting (passes because bufferedLength > 0)
+ * 4. flush() while connecting
+ * 5. Connection completes, _feedQueue processes: [text:Hello., flush, text:" ", flush]
+ * 6. First flush sends "Hello." - OK
+ * 7. Second flush sends " " - BUG!
+ */
+test('TtsStreamingBuffer: multiple flushes while connecting - space token sent to TTS vendor', async(t) => {
+  const cs = createMockCs();
+  const buffer = new TtsStreamingBuffer(cs);
+
+  buffer._connectionStatus = TtsStreamingConnectionStatus.Connecting;
+  buffer.vendor = 'deepgram';
+
+  const apiCalls = [];
+  const originalApi = buffer._api.bind(buffer);
+  buffer._api = async function(ep, args) {
+    apiCalls.push({ args: [...args] });
+    return originalApi(ep, args);
+  };
+
+  // First batch while connecting
+  await buffer.bufferTokens('Hello.');
+  buffer.flush();
+
+  // Second batch - just a space (passes because bufferedLength > 0)
+  await buffer.bufferTokens(' ');
+  buffer.flush();
+
+  // Verify queue state before connect
+  t.equal(buffer.queue.length, 4, 'queue should have 4 items: [text, flush, text, flush]');
+  t.equal(buffer.queue[0].type, 'text', 'first item should be text');
+  t.equal(buffer.queue[0].value, 'Hello.', 'first text should be "Hello."');
+  t.equal(buffer.queue[1].type, 'flush', 'second item should be flush');
+  t.equal(buffer.queue[2].type, 'text', 'third item should be text');
+  t.equal(buffer.queue[2].value, ' ', 'third item should be space');
+  t.equal(buffer.queue[3].type, 'flush', 'fourth item should be flush');
+
+  // Connect - triggers _feedQueue
+  buffer._connectionStatus = TtsStreamingConnectionStatus.Connected;
+  await buffer._feedQueue();
+
+  // Check API calls
+  const sendCalls = apiCalls.filter(call => call.args[1] === 'send');
+
+  // This assertion will FAIL until the bug is fixed
+  const whitespaceOnlySends = sendCalls.filter(call => /^\s*$/.test(call.args[2]));
+
+  t.equal(whitespaceOnlySends.length, 0,
+    `should not send whitespace-only tokens, but sent: ${whitespaceOnlySends.map(c => JSON.stringify(c.args[2])).join(', ')}`);
+
+  t.end();
+});
+
+/**
+ * Additional test: Verify text with trailing space in same flush is OK
+ */
+test('TtsStreamingBuffer: text with trailing space in same flush should work', async(t) => {
+  const cs = createMockCs();
+  const buffer = new TtsStreamingBuffer(cs);
+
+  buffer._connectionStatus = TtsStreamingConnectionStatus.Connecting;
+  buffer.vendor = 'deepgram';
+
+  const apiCalls = [];
+  const originalApi = buffer._api.bind(buffer);
+  buffer._api = async function(ep, args) {
+    apiCalls.push({ args: [...args] });
+    return originalApi(ep, args);
+  };
+
+  // Buffer text with trailing space, then flush
+  await buffer.bufferTokens('Hello.');
+  await buffer.bufferTokens(' ');
+  buffer.flush();
+
+  // Connect
+  buffer._connectionStatus = TtsStreamingConnectionStatus.Connected;
+  await buffer._feedQueue();
+
+  const sendCalls = apiCalls.filter(call => call.args[1] === 'send');
+
+  t.equal(sendCalls.length, 1, 'should have one send call');
+  t.equal(sendCalls[0].args[2], 'Hello. ', 'should send "Hello. " (text with trailing space)');
+
+  t.end();
+});
+
+/**
+ * Test: Leading whitespace should be discarded when buffer is empty
+ */
+test('TtsStreamingBuffer: leading whitespace discarded when buffer empty', async(t) => {
+  const cs = createMockCs();
+  const buffer = new TtsStreamingBuffer(cs);
+
+  buffer._connectionStatus = TtsStreamingConnectionStatus.Connected;
+  buffer.vendor = 'deepgram';
+
+  // Try to buffer whitespace when buffer is empty
+  const result = await buffer.bufferTokens('   ');
+
+  t.equal(result.status, 'ok', 'should return ok status');
+  t.equal(buffer.bufferedLength, 0, 'buffer should remain empty');
+  t.equal(buffer.queue.length, 0, 'queue should remain empty');
+
+  t.end();
+});
+
+/**
+ * Test: Whitespace can be buffered when buffer has content
+ */
+test('TtsStreamingBuffer: whitespace accepted when buffer has content', async(t) => {
+  const cs = createMockCs();
+  const buffer = new TtsStreamingBuffer(cs);
+
+  buffer._connectionStatus = TtsStreamingConnectionStatus.Connecting;
+  buffer.vendor = 'deepgram';
+
+  // Buffer real text first
+  await buffer.bufferTokens('Hello');
+
+  // Now buffer whitespace (should pass because bufferedLength > 0)
+  const result = await buffer.bufferTokens(' ');
+
+  t.equal(result.status, 'ok', 'should return ok status');
+  t.equal(buffer.bufferedLength, 6, 'buffer should have 6 chars');
+  t.equal(buffer.queue.length, 2, 'queue should have 2 items');
+
+  t.end();
+});