chore(tts): halve per-chunk size to 500 chars to reduce cutouts; add TTS chunker test

Author: hackall360

src/main.js

@@ -850,9 +850,9 @@ function groupSentences(sentences, groupSize = 2) {
 }
 
 // Build TTS chunks by character length, prefer ending at sentence boundaries.
-// - maxChars: hard cap per chunk (default 1000)
+// - maxChars: hard cap per chunk (default 500)
 // - If a single sentence exceeds max, split it on whitespace near the limit.
-function buildTtsChunks(text, { maxChars = 1000 } = {}) {
+function buildTtsChunks(text, { maxChars = 500 } = {}) {
   const sents = splitIntoSentences(text);
   const chunks = [];
   let i = 0;
@@ -947,7 +947,7 @@ function startVoicePlaybackForMessage(message, voice) {
   cancelCurrentTtsJob();
   const raw = stripNonSpokenParts(message.content || '');
   if (!raw) return;
-  const chunks = buildTtsChunks(raw, { maxChars: 1000 });
+  const chunks = buildTtsChunks(raw, { maxChars: 500 });
   if (!chunks.length) return;
 
   const job = {

tests/tts-chunker.test.mjs

@@ -0,0 +1,15 @@
+import assert from 'node:assert/strict';
+import { readFile } from 'node:fs/promises';
+
+export const name = 'TTS chunker: halved payload (500 char cap) wired in call site';
+
+export async function run() {
+  const js = await readFile(new URL('../src/main.js', import.meta.url), 'utf8');
+  const defMatch = js.match(/function\s+buildTtsChunks\s*\(text,\s*\{\s*maxChars\s*=\s*(\d+)\s*\}\s*=\s*\{\}\)\s*\{/);
+  const defaultMax = defMatch ? Number(defMatch[1]) : null;
+  assert.equal(defaultMax, 500, 'default maxChars must be 500');
+
+  const callMatch = js.match(/buildTtsChunks\(raw,\s*\{\s*maxChars:\s*(\d+)\s*\}\s*\)/);
+  const callMax = callMatch ? Number(callMatch[1]) : null;
+  assert.equal(callMax, 500, 'startVoicePlaybackForMessage should request 500-char chunks');
+}