fix(tts): custom engine availability follows health, not the library voice list

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -6,6 +6,8 @@ Follows [Keep a Changelog](https://keepachangelog.com/en/1.0.0/) · versioned wi
 ---
 
 ## [Unreleased]
+### Fixed
+- Custom TTS engines no longer count as available just because the app's own voice library is non-empty: availability follows the engine's health, so a stopped VoiceDesign/CustomVoice container is no longer listed.
 
 ---
 

routes/tts.py

@@ -457,7 +457,8 @@ def _backend_configured(settings: dict, backend: str, voices: list) -> bool:
 
 
 def _backend_available(backend: str, voices: list, health: bool) -> bool:
-    if _clean_preview_backend(backend) in {"nvidia_zeroshot", "nvidia_flow", "kokoro", "vibevoice", "fishspeech"}:
+    # A custom engine's voice list is the app's own library, so it proves nothing about the engine.
+    if backend.startswith("custom:") or _clean_preview_backend(backend) in {"nvidia_zeroshot", "nvidia_flow", "kokoro", "vibevoice", "fishspeech"}:
         return health
     return bool(voices) or health
 

tests/test_tts_health_probe.py

@@ -95,5 +95,16 @@ class GatewayUpstreamProbeTests(unittest.TestCase):
         self.assertEqual(get.call_count, 1)  # second lookup served from the cache
 
 
+class CustomAvailabilityTests(unittest.TestCase):
+    def test_custom_engine_availability_follows_health_not_the_library_voice_list(self):
+        library = ["EN_F_a", "DE_M_b"]
+        self.assertFalse(tts._backend_available("custom:abc", library, False))
+        self.assertTrue(tts._backend_available("custom:abc", [], True))
+
+    def test_builtin_backends_keep_their_rules(self):
+        self.assertTrue(tts._backend_available("voice_clone", ["x"], False))
+        self.assertFalse(tts._backend_available("kokoro", ["x"], False))
+
+
 if __name__ == "__main__":
     unittest.main()