fix(offline): remove inference-path HF_HUB_OFFLINE guards

0.4.3 wrapped every inference body (`generate`, `transcribe`,
`create_voice_clone_prompt`) with `force_offline_if_cached(True, …)` to
prevent lazy HF lookups from hanging when the network drops
mid-inference (#462). That trade broke online users: the guard flips
`huggingface_hub.constants.HF_HUB_OFFLINE` globally, so any legitimate
metadata call the library makes during generation (e.g. revision
resolution via `HfApi().model_info`) now raises:

    Cannot reach https://huggingface.co/api/models/Qwen/Qwen3-TTS-…:
    offline mode is enabled.

Hit by multiple users on 0.4.3 within hours of release. The offline
blast radius is much larger than the original hang it fixed.

This reverts the inference-path guards. Load-path guards stay — those
worked fine in 0.4.2 and aren't the source of the regression. The
`force_offline_if_cached` helper itself is unchanged; tests still pass.

The #462 hang (network dropping mid-inference) remains unaddressed by
this commit and will need a targeted fix that doesn't flip a global
flag — most likely per-call timeouts or library-specific
`local_files_only` arguments, not a process-wide env mutation.

backend/backends/mlx_backend.py

@@ -193,8 +193,6 @@ class MLXTTSBackend:
 
         logger.info("Generating audio for text: %s", text)
 
-        model_name = f"qwen-tts-{self._current_model_size}"
-
         def _generate_sync():
             """Run synchronous generation in thread pool."""
             # MLX generate() returns a generator yielding GenerationResult objects
@@ -220,14 +218,12 @@ class MLXTTSBackend:
                 logger.warning("Regenerating without voice prompt.")
                 ref_audio = None
 
-            # Model is loaded → weights are on disk. Force offline so
-            # lazy tokenizer/config lookups inside mlx_audio don't hang
-            # when the user is disconnected (issue #462).
-            with force_offline_if_cached(True, model_name):
-                # Check if model supports voice cloning via generate method
-                # MLX API may support ref_audio parameter directly
+            # Inference runs with the process's default HF_HUB_OFFLINE
+            # state. Forcing offline here (previously used to avoid lazy
+            # mlx_audio lookups hanging when the network drops mid-inference,
+            # issue #462) regressed online users because libraries make
+            # legitimate metadata calls during generation.
             try:
-                    # Try with voice cloning parameters if supported
                 if ref_audio:
                     # Check if generate accepts ref_audio parameter
                     import inspect
@@ -347,8 +343,6 @@ class MLXSTTBackend:
         """
         await self.load_model_async(model_size)
 
-        progress_model_name = f"whisper-{self.model_size}"
-
         def _transcribe_sync():
             """Run synchronous transcription in thread pool."""
             # MLX Whisper transcription using generate method
@@ -357,10 +351,9 @@ class MLXSTTBackend:
             if language:
                 decode_options["language"] = language
 
-            # Model is loaded → weights are on disk. Force offline so
-            # lazy tokenizer/config lookups don't hang when the user is
-            # disconnected (issue #462).
-            with force_offline_if_cached(True, progress_model_name):
+            # Inference runs with the process's default HF_HUB_OFFLINE
+            # state — see the comment in MLXTTSBackend.generate for the
+            # regression this revert fixes (issue #462).
             result = self.model.generate(str(audio_path), **decode_options)
 
             # Extract text from result

backend/backends/pytorch_backend.py

@@ -172,14 +172,12 @@ class PyTorchTTSBackend:
                     # This shouldn't happen in practice, but handle it
                     return {"prompt": cached_prompt}, True
 
-        model_name = f"qwen-tts-{self._current_model_size}"
-
         def _create_prompt_sync():
             """Run synchronous voice prompt creation in thread pool."""
-            # Model is loaded → weights are on disk. Force offline so
-            # lazy tokenizer/config lookups inside qwen_tts don't hang
-            # when the user is disconnected (issue #462).
-            with force_offline_if_cached(True, model_name):
+            # Inference runs with the process's default HF_HUB_OFFLINE
+            # state. Forcing offline here (issue #462) regressed online
+            # users whose libraries issue legitimate metadata lookups
+            # during voice-prompt creation.
             return self.model.create_voice_clone_prompt(
                 ref_audio=str(audio_path),
                 ref_text=reference_text,
@@ -227,18 +225,14 @@ class PyTorchTTSBackend:
         # Load model
         await self.load_model_async(None)
 
-        model_name = f"qwen-tts-{self._current_model_size}"
-
         def _generate_sync():
             """Run synchronous generation in thread pool."""
             # Set seed if provided
             if seed is not None:
                 manual_seed(seed, self.device)
 
-            # Model is loaded → weights are on disk. Force offline so
-            # lazy tokenizer/config lookups inside qwen_tts don't hang
-            # when the user is disconnected (issue #462).
-            with force_offline_if_cached(True, model_name):
+            # See _create_prompt_sync comment — inference runs with the
+            # process's default HF_HUB_OFFLINE state (issue #462).
             wavs, sample_rate = self.model.generate_voice_clone(
                 text=text,
                 voice_clone_prompt=voice_prompt,
@@ -342,17 +336,15 @@ class PyTorchSTTBackend:
         """
         await self.load_model_async(model_size)
 
-        progress_model_name = f"whisper-{self.model_size}"
-
         def _transcribe_sync():
             """Run synchronous transcription in thread pool."""
             # Load audio
             audio, _sr = load_audio(audio_path, sample_rate=16000)
 
-            # Model is loaded → weights are on disk. Force offline so
-            # `get_decoder_prompt_ids` and any lazy tokenizer lookups
-            # don't hang when the user is disconnected (issue #462).
-            with force_offline_if_cached(True, progress_model_name):
+            # Inference runs with the process's default HF_HUB_OFFLINE
+            # state — forcing offline here (issue #462) broke online users
+            # whose `get_decoder_prompt_ids` / tokenizer calls issue
+            # legitimate metadata lookups.
             # Process audio
             inputs = self.processor(
                 audio,

backend/backends/qwen_custom_voice_backend.py

@@ -186,7 +186,6 @@ class QwenCustomVoiceBackend:
         await self.load_model_async(None)
 
         speaker = voice_prompt.get("preset_voice_id") or QWEN_CV_DEFAULT_SPEAKER
-        model_name = f"qwen-custom-voice-{self._current_model_size}"
 
         def _generate_sync():
             if seed is not None:
@@ -206,10 +205,10 @@ class QwenCustomVoiceBackend:
             if instruct:
                 kwargs["instruct"] = instruct
 
-            # Model is loaded → weights are on disk. Force offline so
-            # lazy tokenizer/config lookups inside qwen_tts don't hang
-            # when the user is disconnected (issue #462).
-            with force_offline_if_cached(True, model_name):
+            # Inference runs with the process's default HF_HUB_OFFLINE
+            # state. Forcing offline here (issue #462) regressed online
+            # users whose libraries issue legitimate metadata lookups
+            # during generation.
             wavs, sample_rate = self.model.generate_custom_voice(**kwargs)
             return wavs[0], sample_rate