Auto-download Kokoro model files if missing at startup

Replaces the FileNotFoundError with _ensure_kokoro_models() which
downloads kokoro-v1.0.onnx and voices-v1.0.bin from the kokoro-onnx
GitHub releases if they are absent — handles the HF Space ephemeral
filesystem without breaking local or modal configurations.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

visualnovel/tts.py

@@ -69,6 +69,27 @@ _FEMALE_GENDER_HINTS = {"woman", "female", "her", "she", "girl", "lady"}
 
 _MODEL_PATH  = config.MODELS_DIR / "kokoro" / "kokoro-v1.0.onnx"
 _VOICES_PATH = config.MODELS_DIR / "kokoro" / "voices-v1.0.bin"
+_KOKORO_BASE_URL = (
+    "https://github.com/thewh1teagle/kokoro-onnx/releases/download/model-files-v1.0"
+)
+
+
+def _ensure_kokoro_models() -> None:
+    """Download Kokoro model files if absent (handles HF Space ephemeral filesystem)."""
+    files = {
+        _MODEL_PATH: f"{_KOKORO_BASE_URL}/kokoro-v1.0.onnx",
+        _VOICES_PATH: f"{_KOKORO_BASE_URL}/voices-v1.0.bin",
+    }
+    missing = {p: u for p, u in files.items() if not p.exists()}
+    if not missing:
+        return
+    import urllib.request
+
+    _MODEL_PATH.parent.mkdir(parents=True, exist_ok=True)
+    for path, url in missing.items():
+        print(f"[tts] Downloading {path.name} …", flush=True)
+        urllib.request.urlretrieve(url, path)
+        print(f"[tts] {path.name} ready ({path.stat().st_size // 1_000_000} MB)", flush=True)
 
 
 def _pick_voice(voice_description: str, sprite_seed: int) -> str:
@@ -106,16 +127,7 @@ class KokoroTTS:
     def __init__(self) -> None:
         from kokoro_onnx import Kokoro  # noqa: PLC0415
 
-        if not _MODEL_PATH.exists() or not _VOICES_PATH.exists():
-            raise FileNotFoundError(
-                f"Kokoro model files missing from {_MODEL_PATH.parent}.\n"
-                "Download them with:\n"
-                "  curl -L -o models/kokoro/kokoro-v1.0.onnx \\\n"
-                "    https://github.com/thewh1teagle/kokoro-onnx/releases/download/model-files-v1.0/kokoro-v1.0.onnx\n"
-                "  curl -L -o models/kokoro/voices-v1.0.bin \\\n"
-                "    https://github.com/thewh1teagle/kokoro-onnx/releases/download/model-files-v1.0/voices-v1.0.bin"
-            )
-
+        _ensure_kokoro_models()
         self._kokoro = Kokoro(str(_MODEL_PATH), str(_VOICES_PATH))
         # Filter profiles to voices actually present in the loaded model
         available = set(self._kokoro.get_voices())