Review follow-up:
- Wrap the `_offline_refcount == 0` setup in a try/except so any failure
during the cached-constant mutation (including unexpected non-ImportError
like RuntimeError or AttributeError from a half-initialized module)
rolls back *all* partial state before re-raising. Without this, a
mid-setup crash could leave `huggingface_hub.constants.HF_HUB_OFFLINE`
mutated but the refcount at 0 — a persistent offline flag outliving
the process.
- Swap ruff-flagged Yoda comparisons in the new test file (SIM300) and
add a module-level note warning that these tests mutate global state
and are not safe under cross-process parallelism.
Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>
Review feedback on the initial fix surfaced two real issues:
1. ``os.environ`` toggles alone don't flip offline mode.
``huggingface_hub.constants.HF_HUB_OFFLINE`` is read once at import
time into a module-level bool; ``transformers.utils.hub._is_offline_mode``
mirrors that bool at its own import time. The hot paths
(``_http._default_backend_factory`` in huggingface_hub,
``is_offline_mode`` in transformers) read the cached bools — not the
env — so mutating only ``os.environ`` was a no-op.
2. Race condition on concurrent inference. Two threads running inside
``force_offline_if_cached`` via ``asyncio.to_thread`` could have
thread A's ``finally`` strip thread B's offline protection mid-run.
Rewrite the helper to:
- mutate ``huggingface_hub.constants.HF_HUB_OFFLINE`` and
``transformers.utils.hub._is_offline_mode`` directly
- refcount concurrent users under a single ``threading.RLock`` so a
shared offline window is restored only when the last caller exits
- still write ``os.environ`` for anything that reads it dynamically
Also addresses the unused-variable ruff flag on the Whisper transcribe
path (``audio, sr`` → ``audio, _sr``).
New unit tests cover the cached-constant mutation, env propagation,
no-op on ``is_cached=False``, nested contexts, and a threaded race
where a slow thread must retain offline mode after a peer exits.
Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>
Qwen TTS and Whisper Base make network calls to HuggingFace even when
model weights are fully cached locally, because from_pretrained()
defaults to local_files_only=False. This causes failures for offline
users.
Add a reusable force_offline_if_cached() context manager that sets
HF_HUB_OFFLINE=1 during model loading when is_model_cached() is True.
Applied to all four affected load paths:
- PyTorchTTSBackend (Qwen TTS)
- PyTorchSTTBackend (Whisper)
- MLXTTSBackend (refactored from inline implementation)
- MLXSTTBackend (previously unprotected)
Closes#82
Backend:
- Generation service reports 'loading_model' status only when model
is not yet in memory, then 'generating' once inference starts
- Migrate hf_offline_patch.py from print() to logging module
- Update ADDING_TTS_ENGINES.md for post-refactor file paths
Frontend:
- HistoryTable shows 'Loading model...' vs 'Generating...' based on step
- FloatingGenerateBox: replace instruct toggle + inline effects editor
with an effects preset dropdown (third dropdown after language and engine)
- Instruct UI removed for now (form field preserved for future models)
- Remove focus ring from Select component globally
Implements offline mode patch for API stability issues:
- Add hf_offline_patch.py to monkey-patch huggingface_hub
- Force cache-only lookups before mlx_audio imports
- Create symlink from original Qwen repo to MLX community version
when only MLX version is cached
This fixes:
- Issue #150: Internet required even with cached models
- Issue #151: API crashes when HF network fails
The patch ensures that if models are locally cached, no network
requests are made to HuggingFace during speech generation.
