[add] Load voice parameters from .env file

Configure Piper TTS synthesis via environment variables (speaker_id,
length_scale, noise_scale, noise_w_scale, volume) loaded from .env
with python-dotenv. Includes .env.example as reference template.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.env.example

@@ -0,0 +1,10 @@
+# Piper TTS voice configuration
+VOICE_MODEL=en_GB-alan-medium.onnx       # Path to Piper .onnx voice model (relative to project root)
+VOICE_SPEAKER_ID=                         # Speaker ID for multi-speaker models (integer, leave empty for default)
+VOICE_LENGTH_SCALE=                       # Speech speed: >1.0 = slower, <1.0 = faster (leave empty for model default)
+VOICE_NOISE_SCALE=                        # Phoneme variability: 0.0 = robotic, 1.0 = expressive (leave empty for model default)
+VOICE_NOISE_W_SCALE=                      # Phoneme width variability (leave empty for model default)
+VOICE_VOLUME=1.0                          # Playback volume multiplier (default: 1.0)
+
+# Vosk STT configuration
+STT_MODEL=vosk-model-small-en-us-0.15    # Vosk model directory name (relative to project root)

.gitignore

@@ -4,3 +4,4 @@ __pycache__/
 save.qzl
 vosk-model-*/
 .wolf
+.env

h2g2/engine/tts.py

@@ -9,13 +9,29 @@ import wave
 from pathlib import Path
 
 from piper import PiperVoice
+from piper.config import SynthesisConfig
 
 
 class TTS:
     """Speaks text using Piper TTS and aplay for playback."""
 
-    def __init__(self, model_path: str | Path) -> None:
+    def __init__(
+        self,
+        model_path: str | Path,
+        speaker_id: int | None = None,
+        length_scale: float | None = None,
+        noise_scale: float | None = None,
+        noise_w_scale: float | None = None,
+        volume: float = 1.0,
+    ) -> None:
         self._voice = PiperVoice.load(str(model_path))
+        self._syn_config = SynthesisConfig(
+            speaker_id=speaker_id,
+            length_scale=length_scale,
+            noise_scale=noise_scale,
+            noise_w_scale=noise_w_scale,
+            volume=volume,
+        )
         self._thread: threading.Thread | None = None
         self._last_wav: bytes | None = None
 
@@ -39,7 +55,7 @@ class TTS:
     def _synthesize(self, text: str) -> bytes:
         buf = io.BytesIO()
         with wave.open(buf, "wb") as wav_file:
-            self._voice.synthesize_wav(text, wav_file)
+            self._voice.synthesize_wav(text, wav_file, syn_config=self._syn_config)
         return buf.getvalue()
 
     def _play(self, wav_data: bytes) -> None:

h2g2/main.py

@@ -2,8 +2,11 @@
 """The Hitchhiker's Guide to the Galaxy — Python text adventure engine."""
 
 import argparse
+import os
 from pathlib import Path
 
+from dotenv import load_dotenv
+
 from h2g2.engine.clock import Clock
 from h2g2.engine.loop import GameLoop
 from h2g2.engine.output import Output
@@ -17,9 +20,25 @@ import h2g2.engine.verbs  # noqa: F401
 # Import content modules
 from h2g2.content import globals_content, earth, vogon, heart, unearth, dark
 
-# Default model locations (project root)
-_DEFAULT_VOICE = Path(__file__).resolve().parent.parent / "en_GB-alan-medium.onnx"
-_DEFAULT_STT_MODEL = Path(__file__).resolve().parent.parent / "vosk-model-small-en-us-0.15"
+# Load .env from project root
+_PROJECT_ROOT = Path(__file__).resolve().parent.parent
+load_dotenv(_PROJECT_ROOT / ".env")
+
+# Default model locations (from env or project root)
+_DEFAULT_VOICE = _PROJECT_ROOT / os.getenv("VOICE_MODEL", "en_GB-alan-medium.onnx")
+_DEFAULT_STT_MODEL = _PROJECT_ROOT / os.getenv("STT_MODEL", "vosk-model-small-en-us-0.15")
+
+
+def _env_float(key: str) -> float | None:
+    """Read an env var as float, returning None if empty/unset."""
+    val = os.getenv(key, "").strip()
+    return float(val) if val else None
+
+
+def _env_int(key: str) -> int | None:
+    """Read an env var as int, returning None if empty/unset."""
+    val = os.getenv(key, "").strip()
+    return int(val) if val else None
 
 
 def main() -> None:
@@ -116,7 +135,14 @@ def main() -> None:
     tts = None
     if args.audio:
         from h2g2.engine.tts import TTS
-        tts = TTS(args.voice)
+        tts = TTS(
+            args.voice,
+            speaker_id=_env_int("VOICE_SPEAKER_ID"),
+            length_scale=_env_float("VOICE_LENGTH_SCALE"),
+            noise_scale=_env_float("VOICE_NOISE_SCALE"),
+            noise_w_scale=_env_float("VOICE_NOISE_W_SCALE"),
+            volume=_env_float("VOICE_VOLUME") or 1.0,
+        )
 
     # Initialize STT if requested
     stt = None

pyproject.toml

@@ -8,6 +8,7 @@ dependencies = [
     "piper-tts>=1.2.0",
     "vosk>=0.3.45",
     "pyaudio>=0.2.14",
+    "python-dotenv>=1.0.0",
 ]
 
 [build-system]