feat(tts): bump base speed 1.0→1.15 for slightly faster delivery

User asked for a bit faster speech. Pitch shift is already disabled, so the
earlier "monster voice" risk from stacking pitch on a fast base is gone — a
modest 1.15x base is natural. Emotion multipliers scale off base, so every
emotion gets the bump too. Also adds tests/gen_emotion_samples.py, a dev
utility that synthesizes one clip per canonical emotion (announce name at
neutral speed, then a sample sentence steered by that emotion's tag) and
stitches them into a single wav for auditioning the emotion palette.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/gen_emotion_samples.py

@@ -0,0 +1,76 @@
+"""One-off: synthesize a short Korean sample for every canonical emotion and
+stitch them into a single wav so the delivery of each emotion can be heard.
+
+Each clip announces the emotion name at neutral (base) speed, then speaks a
+sample sentence steered by that emotion's ``[태그]`` — exactly the path the live
+voice server uses. Run with the orchestrator venv:
+
+    .venv/bin/python -m tests.gen_emotion_samples /abs/out.wav
+"""
+
+from __future__ import annotations
+
+import asyncio
+import sys
+import wave
+
+from wsai.backends.melo import MeloTTS
+
+# (announced Korean name, emotion tag word, sample sentence)
+SAMPLES: list[tuple[str, str, str]] = [
+    ("기쁨",        "기쁨",        "오늘은 정말 기분 좋은 하루예요!"),
+    ("신남",        "신남",        "우와, 이거 진짜 신난다! 빨리 하자!"),
+    ("희망",        "희망",        "우리 분명히 잘 해낼 수 있어요!"),
+    ("슬픔",        "슬픔",        "조금 속상한 일이 있었어요."),
+    ("화남",        "화남",        "정말 너무하잖아요, 화가 나요."),
+    ("두려움",      "두려움",      "어떡하지, 너무 무서워요."),
+    ("놀람",        "놀람",        "어머, 이게 정말이에요?"),
+    ("혐오",        "혐오",        "으, 이건 좀 별로예요."),
+    ("차분",        "차분",        "천천히 하나씩 정리해 볼게요."),
+    ("다정",        "다정",        "언제든지 편하게 말해 주세요."),
+    ("진지",        "진지",        "이건 정말 중요한 이야기예요."),
+    ("실망",        "실망",        "조금 아쉬운 결과네요."),
+    ("피곤",        "피곤",        "아, 오늘 너무 피곤하네요."),
+    ("사랑스럽게",  "사랑스럽게",  "당신은 정말 소중한 사람이에요."),
+    ("장난스럽게",  "장난스럽게",  "히히, 한번 맞혀 보세요!"),
+    ("궁금",        "궁금",        "그건 대체 왜 그런 걸까요?"),
+    ("속삭임",      "속삭임",      "조용히, 우리끼리만 아는 비밀이에요."),
+    ("외침",        "외침",        "다 같이 힘내자, 파이팅!"),
+    ("단호",        "단호",        "이번엔 반드시 해내겠어요."),
+    ("안도",        "안도",        "휴, 이제야 마음이 놓이네요."),
+]
+
+
+def stitch(paths: list[str], out: str, gap_s: float = 0.45) -> None:
+    with wave.open(paths[0], "rb") as w0:
+        nch, sw, fr = w0.getnchannels(), w0.getsampwidth(), w0.getframerate()
+    silence = b"\x00" * (int(fr * gap_s) * sw * nch)
+    with wave.open(out, "wb") as wo:
+        wo.setnchannels(nch)
+        wo.setsampwidth(sw)
+        wo.setframerate(fr)
+        for i, p in enumerate(paths):
+            with wave.open(p, "rb") as w:
+                wo.writeframes(w.readframes(w.getnframes()))
+            if i < len(paths) - 1:
+                wo.writeframes(silence)
+
+
+async def main(out: str) -> None:
+    tts = MeloTTS()  # base speed comes from the new WSAI_TTS_SPEED default (1.15)
+    await tts.warmup()
+    print(f"melo ready ({tts.load_ms} ms), base speed {tts.speed}")
+    paths: list[str] = []
+    for name, tag, sample in SAMPLES:
+        text = f"{name}. [{tag}] {sample}"
+        p = await tts.synth(text)
+        paths.append(p)
+        print(f"  {name:8s} -> {p}")
+    await tts.aclose()
+    stitch(paths, out)
+    print(f"stitched {len(paths)} clips -> {out}")
+
+
+if __name__ == "__main__":
+    out = sys.argv[1] if len(sys.argv) > 1 else "/tmp/emotion_samples.wav"
+    asyncio.run(main(out))

wsai/backends/melo.py

@@ -12,7 +12,7 @@ Env:
     WSAI_MELO_DEVICE   cpu | cuda | auto  (default auto: GPU if torch sees one,
                        else CPU; the worker falls back to CPU if CUDA fails)
     WSAI_TTS_OUT_DIR   where wavs are written (default ~/.cache/wsai/tts)
-    WSAI_TTS_SPEED     synthesis speed multiplier (default 1.0)
+    WSAI_TTS_SPEED     synthesis speed multiplier (default 1.15)
 """
 
 from __future__ import annotations
@@ -93,7 +93,7 @@ class MeloTTS:
         self.out_dir = Path(out_dir or os.environ.get("WSAI_TTS_OUT_DIR")
                             or (Path.home() / ".cache/wsai/tts"))
         self.speed = float(speed if speed is not None
-                           else os.environ.get("WSAI_TTS_SPEED", "1.0"))
+                           else os.environ.get("WSAI_TTS_SPEED", "1.15"))
         self.sink = sink or _log_sink
         self._proc: asyncio.subprocess.Process | None = None
         self._lock = asyncio.Lock()