The fit corpus was limited to three hardcoded choices (wikitext, Semantic-Harmless, mixed), and any other id was rejected. Now any HuggingFace dataset id works, and any number of them can be ticked to fit on an equal-parts mix, shuffled.
n_prompts now counts training SEQUENCES (what the fit iterates over) instead of source rows: each dataset is packed up to its quota, so the number entered is exactly what runs, regardless of the dataset. The fixed dropdown becomes a checkable dataset library persisted in localStorage.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>