Stabilize German TTS sentence chunking

compose.yaml

@@ -685,6 +685,9 @@ services:
       TTS_CODE_SWITCH_ENABLED: "false"
       XTTS_QUEUE_TIMEOUT: "15"
       XTTS_TIMEOUT: "120"
+      # Short sentence-sized requests avoid long generated silences and
+      # truncated weather/status summaries with Annmarie Nele.
+      XTTS_CHUNK_CHARS: "60"
       PIPER_TIMEOUT: "120"
     networks: [frontend]
     depends_on:

platform/docker/tts-gateway/test_tts_gateway.py

@@ -110,6 +110,20 @@ class LanguageSegmentationTests(unittest.TestCase):
                 self.assertIn("29 Kilometer pro Stunde", spoken)
                 self.assertNotIn("km", spoken.lower())
 
+    def test_weather_summary_is_split_into_short_complete_chunks(self):
+        text = (
+            "Heute in Rastatt: teils sonnig, trocken, 10 bis 22 Grad. "
+            "Abends wolkiger, 16 bis 21 Grad. Böen bis 29 km/h. "
+            "Kein Regen erwartet. Quelle: wetter.com, wetteronline.de"
+        )
+        segments = gateway.prepare_segments(text)
+        spoken = " ".join(part for _, part in segments)
+        self.assertEqual(len(segments), 4)
+        self.assertTrue(all(len(part) <= 60 for _, part in segments))
+        self.assertIn("29 Kilometer pro Stunde", spoken)
+        self.assertIn("Kein Regen erwartet", spoken)
+        self.assertIn("wetteronline Punkt de", spoken)
+
 
 class FallbackTests(unittest.TestCase):
     def setUp(self):

platform/docker/tts-gateway/tts_gateway.py

@@ -38,7 +38,10 @@ MAX_AUDIO_BYTES = int(os.getenv("TTS_MAX_AUDIO_BYTES", str(64 * 1024 * 1024)))
 XTTS_TIMEOUT = float(os.getenv("XTTS_TIMEOUT", "120"))
 PIPER_TIMEOUT = float(os.getenv("PIPER_TIMEOUT", "120"))
 QUEUE_TIMEOUT = float(os.getenv("XTTS_QUEUE_TIMEOUT", "15"))
-CHUNK_CHARS = int(os.getenv("XTTS_CHUNK_CHARS", "220"))
+# XTTS can insert multi-second silences or truncate the remainder when a
+# moderately long German paragraph is sent as one request.  Keeping requests
+# close to one sentence proved substantially more stable with Annmarie Nele.
+CHUNK_CHARS = int(os.getenv("XTTS_CHUNK_CHARS", "60"))
 TRIM_THRESHOLD = int(os.getenv("XTTS_TRIM_THRESHOLD", "90"))
 TRIM_PADDING_MS = int(os.getenv("XTTS_TRIM_PADDING_MS", "18"))
 CROSSFADE_MS = int(os.getenv("XTTS_CROSSFADE_MS", "8"))