✗ training failed: _lora_dir() missing 1 required positional argument: 'name'

Progress, in that everything before it worked: the Train button built the dataset,
the request carried dataset_config, the server accepted it and dispatched to the
LongCat path. It then died on the first line of _train_externally that does real
work — proof that function had never once executed.

Two bugs in one line. _lora_dir(name) already resolves the per-LoRA directory AND
routes a non-main DDP rank to scratch; the call treated it as the parent and
joined the name on again, so even with the argument supplied it would have written
<loras>/<name>/<name> and bypassed the DDP handling.

The test calls the real _train_externally with only the worker stubbed — no GPU,
no checkpoint, no venv — and checks it reaches the worker, that output_dir equals
_lora_dir(name) with the name not doubled, that the job carries steps/rank/seed/
num_frames/dataset_config, that both refusal paths still refuse, and that the
worker's **kwargs progress callback matches the receiver's signature (a mismatch
there would only show up mid-training).

Verified to FAIL on the real defect: restoring the old line turns 4 of the 6 red
with exactly the TypeError above.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0182DhR1eFNPQyGmDrpHbedY