# 2026-03-09 MLX Run 2

Purpose:

- test whether a larger adaptation surface and longer context beat `mlx-run1`

Config deltas vs `mlx-run1`:

- layers: `16` instead of `12`
- max seq length: `2048` instead of `1536`
- learning rate: `8e-6` instead of `1e-5`
- iters: `1200` instead of `1000`

Training result:

- best validation loss: `0.304` at iter `900`
- final validation loss: `0.639`

Benchmark result:

- `nDCG@10 = 0.8776`
- ask `Recall@5 = 0.875`
- schema success `0.1667`
- p95 `3133ms`

Outcome:

- reject for promotion

Why:

- better validation loss did **not** translate into better exported-model retrieval quality
- structure regressed sharply versus `mlx-run1`
- this run is a concrete example of why promotion must follow benchmark results, not training loss
