Round 7 reviewer surfaced a handful of swap-window races, fail-open
guards, and seed precision mismatches. This commit closes them.
Lifecycle / state (P1)
* core/inference/diffusion.py: status() now emits active_repo_id,
active_base_repo, pending_repo_id, pending_base_repo, and
pending_gguf_filename alongside the existing UI-facing fields.
During a swap (model A loaded, model B loading) the previous
coalesced 'repo_id or pending_repo_id' hid the loading target
from delete guards. Splitting the fields lets guards block
deletion of either repo currently owned by the backend.
* core/inference/diffusion.py: generate_image() now takes
_generate_lock BEFORE snapshotting _pipe / _device. Snapshotting
outside the lock let a concurrent unload/load clear or replace
the backend between the snapshot and the forward, so the freed
or swapped pipeline would still run.
Symmetric handoffs (P1)
* routes/export.py: training-active check now runs BEFORE the
chat / inference / diffusion unload helpers, so a 409 does not
leave the user's chat session torn down for nothing. Also
explicitly fails CLOSED with 503 when is_training_active()
raises.
* routes/inference.py: _raise_if_training_active now fails closed
with 503 when the training backend is importable but its status
check raises. The previous best-effort log-and-continue could
let chat / diffusion loads collide with unverifiable training.
Delete guards (P1)
* routes/models.py /delete-cached: chat guard now also blocks
when llama-server is_active (i.e. mid-download) and when the
inference backend's loading_models set contains the target.
Round 7 review #7 flagged that the PR's diffusion-side loading
guard had no chat-side parallel, so deleting a chat repo while
it was downloading could still race the cache.
* routes/models.py /delete-cached: diffusion guard iterates the
new active_* + pending_* status fields so a delete during a
swap is refused on either repo.
* routes/models.py /delete-finetuned: same active_+ pending
handling, plus the guard now also refuses deletes of a parent
directory that contains the loaded pipeline (round 7 review #6:
rm -rf /exports/flux-model/ could unlink model_index.json that
the live pipeline is reading via mmap).
Seed precision (P2)
* models/inference.py + routes/inference.py: DiffusionGenerate-
Response now carries seed_str alongside the existing numeric
seed. Seeds above Number.MAX_SAFE_INTEGER are rounded by
JSON.parse in the browser; seed_str ships full decimal
precision for display and reproduction.
* frontend/api.ts: DiffusionGenerateResponse types seed_str;
images-page.tsx prefers seed_str over seed in the figure
caption so the displayed value reproduces the image.
* frontend/api.ts: stringifyWithBigInt no longer regex-replaces
sentinel strings over the full JSON output. It pulls the seed
BigInt out, JSON-serialises the remaining payload, and splices
the seed's decimal digits into the resulting object literal at
the known position. Avoids the round 7 #10 case where a
user-supplied prompt equal to '__bigint__:123' was rewritten
into a JSON integer and rejected as a non-string prompt.
Custom HF repo (P2)
* frontend/images-page.tsx: custom panel now exposes a 'Base
diffusers repo' input that maps to DiffusionLoadRequest.
base_repo. Required when a private / mirrored GGUF needs a
non-default base (e.g. a 9B Klein transformer would otherwise
fall back to the 4B base default).
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