Laguna-XS-2.1-sbQ-4bit

A 4-bit imatrix MLX quantization of poolside/Laguna-XS-2.1, calibrated on a generic code + multilingual corpus.

This repo exists as the control. It is the exact same build — same bits, same tool, same commit — as Laguna-XS-2.1-sbQ-cal-4bit, except the imatrix calibration corpus: generic text here, real agent traces there. The comparison between the two is the finding — calibration shifts behaviour and speed at equal perplexity — and a comparison you cannot reproduce is a story, so both sides are published. Read the sbQ-cal card for the full grid and the probe battery; this card carries this build's own numbers.

Published by SoftBacon Software. We publish the whole ladder, losing rungs included. On behavioural probes this build ties or loses to its agent-calibrated sibling on every probe (by 1–2 passes of 96, zero inversions) — that is precisely why it is here.

Measurements (same regime as the sbQ-cal card, 2026-08-23/24)

	this build	sbQ-cal-4bit
size	18 GB	18 GB
decode tok/s	136.5	131.5
speculative tok/s	320.6	315.8
held-out NLL (merged split, cap 8192)	1.4806	1.4802
needle n=72	71/72	71/72
verify_before_assert (n=96)	0.833	0.844
say_not_measured (n=96)	0.354	0.375

It is the slightly faster of the pair — calibration shapes bit allocation, and bit allocation shapes the compute layout — so if you want raw decode speed over agentic-behaviour margins, this is the rung to take. The single dropped needle cell (ctx32000_pos0.5) is dropped by the 8-bit reference too: workload artifact, not quant damage.

Full expert-activation report from calibration: oq_imatrix_report.json (0 dark experts of 256 for this corpus).

What's in the repo

MLX safetensors + tokenizer + chat template, PROVENANCE.md, oq_build.json, oq_imatrix_report.json, and LICENSE.md (OpenMDW-1.1, inherited from the base model).

Reproduce

Build tool and measurement harness: github.com/SoftBacon-Software. Built from poolside's official BF16 with no third party in the chain. The sbQ family name marks SoftBacon builds — unrelated to poolside releases and to community oQ-series quants.