Robust GPU detection: TTSEngine checks torch.cuda.is_available() at model load time, with CPU-safe float32 fallback.

backend.py

@@ -420,11 +420,12 @@ class TTSEngine:
         try:
             from qwen_tts import Qwen3TTSModel
             import torch
-            print("[TTS] Loading CustomVoice model...")
+            device = "cuda" if torch.cuda.is_available() else "cpu"
+            print(f"[TTS] Loading CustomVoice model on {device}...")
             self._custom_voice_model = Qwen3TTSModel.from_pretrained(
                 self._model_ids["custom"],
-                device_map=self.device,
-                dtype=torch.bfloat16,
+                device_map=device,
+                dtype=torch.bfloat16 if device == "cuda" else torch.float32,
             )
             print("[TTS] CustomVoice ready.")
         except Exception as e:
@@ -438,11 +439,12 @@ class TTSEngine:
         try:
             from qwen_tts import Qwen3TTSModel
             import torch
-            print("[TTS] Loading Base (clone) model...")
+            device = "cuda" if torch.cuda.is_available() else "cpu"
+            print(f"[TTS] Loading Base (clone) model on {device}...")
             self._base_model = Qwen3TTSModel.from_pretrained(
                 self._model_ids["base"],
-                device_map=self.device,
-                dtype=torch.bfloat16,
+                device_map=device,
+                dtype=torch.bfloat16 if device == "cuda" else torch.float32,
             )
             print("[TTS] Base ready.")
         except Exception as e:
@@ -456,11 +458,12 @@ class TTSEngine:
         try:
             from qwen_tts import Qwen3TTSModel
             import torch
-            print("[TTS] Loading VoiceDesign model...")
+            device = "cuda" if torch.cuda.is_available() else "cpu"
+            print(f"[TTS] Loading VoiceDesign model on {device}...")
             self._design_model = Qwen3TTSModel.from_pretrained(
                 self._model_ids["design"],
-                device_map=self.device,
-                dtype=torch.bfloat16,
+                device_map=device,
+                dtype=torch.bfloat16 if device == "cuda" else torch.float32,
             )
             print("[TTS] VoiceDesign ready.")
         except Exception as e: