Round 6 reviewers identified several races between load / unload /
generate and several fail-open delete guards. This commit closes
them by widening the lock scope, publishing the pending load
target through status(), and switching delete guards to
fail-closed.
Lifecycle (P1)
* core/inference/diffusion.py: load_model now also takes
_generate_lock. Previous behavior released and reallocated the
pipeline while a generation forward was still iterating
denoising steps, corrupting scheduler state and stacking VRAM.
The forward only briefly touches _lock, so taking it on the
load path does not introduce a deadlock.
* core/inference/diffusion.py: unload_model now also takes
_generate_lock. Without it, /images/unload returned
is_loaded=False while a slow forward was still running, which
let chat / training / export handoffs allocate VRAM on top of
the still-resident pipeline.
* core/inference/diffusion.py: previous pipeline release now
happens BEFORE from_single_file / from_pretrained. Switching
FLUX.2 klein 4B -> 9B on a 16-24 GB GPU was failing because
the new transformer allocation overlapped the old pipe's
residency.
* core/inference/diffusion.py: failed pipeline from_pretrained
now explicitly releases the just-loaded transformer; previously
its weights stayed pinned to GPU until GC and made the next
load more likely to OOM.
Pending-target / delete guards (P1)
* core/inference/diffusion.py: load_model now publishes
_pending_repo_id / _pending_base_repo / _pending_gguf_filename
under _lock at the start of the call (and refreshes
_pending_base_repo when the smart-base / repo defaults resolve).
status() exposes those as 'repo_id' / 'base_repo' /
'gguf_filename' during is_loading=True so delete guards can see
the target before _repo_id is set on success.
* routes/models.py /delete-cached + /delete-finetuned: diffusion
status check now fails CLOSED (HTTP 503) when status() raises.
Both guards previously logged and continued, which could let a
delete proceed against a repo whose status was unverifiable.
* routes/models.py: is_loading is also blocked on both guards
so a mid-download / mid-from_pretrained rmtree is refused.
Symmetric handoffs (P1)
* routes/export.py: /load-checkpoint now refuses with HTTP 409
when training is active instead of calling stop_training().
Chat and /images/load did the same after round 5; export was
the remaining asymmetry that would silently kill a long
training run.
* routes/training.py, routes/inference.py (GGUF and standard
chat), routes/export.py: diffusion handoff now treats
is_loading as is_loaded. The diffusion backend's unload waits
on _load_lock + _generate_lock so an in-flight load completes
first.
Requirements (P1)
* requirements/studio.txt: pin python-multipart explicitly. The
Studio routes package's eager router imports include
routes/datasets.py whose FastAPI UploadFile/File validation
crashes with RuntimeError without it in fresh test envs.
Frontend (P2)
* features/images/api.ts + images-page.tsx: seed handling now
accepts the full [-2^63, 2^64 - 1] range via BigInt. The
previous safe-integer cap rejected valid uint64 seeds the
backend accepts. A small stringify helper emits BigInts as JSON
integers without touching the rest of the payload.
Tests
* test_diffusion_routes.py: load routes/inference.py via
importlib.spec_from_file_location to avoid triggering
routes/__init__.py (which would pull in training / datasets /
data_recipe imports unrelated to diffusion tests).
* test_diffusion_backend.py: status() during is_loading shows
pending repo + base; unload waits for in-flight generation.
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