Run the named template with inputs, write train.jsonl + valid.jsonl
into outputDir, and emit progress events. Mirrors the Python reference:
90/10 split with split_idx = max(1, floor(n * 0.9)), valid = remainder
(or the last row if the remainder is empty).
Run the named template with
inputs, writetrain.jsonl+valid.jsonlintooutputDir, and emit progress events. Mirrors the Python reference: 90/10 split withsplit_idx = max(1, floor(n * 0.9)), valid = remainder (or the last row if the remainder is empty).