The venv built, SimpleTuner 4.9.3 installed, and the trainer RAN — the first time
anything past the setup has executed. It then failed on how it was invoked:

  ValueError: JSON configuration file not found. Paths tried: config/config.json

SimpleTuner takes no --config. Its loader picks a configuration BACKEND and asks
that backend where to look; the JSON one reads CONFIG_PATH (a file, or a directory
holding config.json) and otherwise defaults to ./config/config.json relative to
the working directory. The --config we passed was simply ignored, so it fell
through to the default and found nothing.

Now the backend is named (SIMPLETUNER_CONFIG_BACKEND=json) and the path handed
over in CONFIG_PATH, read from the installed package's own json_file.py rather
than guessed. The same config is also written to <workdir>/config/config.json, so
a loader change that ignored CONFIG_PATH would still find it.

Worth recording what this run proved, since all of it was unexercised an hour ago:
the vendored source resolves, the training venv rebuilds itself with a 3.12+
interpreter, SimpleTuner installs from PyPI into it, and the job reaches
SimpleTuner's own argument parsing. The dataset built from the township clips has
not been read yet — that is the next thing in the way.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0182DhR1eFNPQyGmDrpHbedY