Research / Study · October 2026 · 8 min read

What the right harnessdoes for small models

On a loading-dock shift, small open models scored zero choosing every move. Planning while a harness carried out the moves, they reached 63–82.

Shift replay · cost of delaysEnv · loading-dock / dc-v1Bank scenario 3 of 12Tick 24 / 24 · lower is better
Real episode · Oct 16, 2026
Same model, alone · $21,13073.89B open model · in harness · $5,140Scripted expert · $5,020 · 74.6
7 of 24 ticksadded cost · in harness
Summary

We ran frontier, small open and scripted policies on a fixed bank of 12 loading-dock scenarios. Frontier models choosing every move scored 93.7–99.4. Small open models choosing every move mostly scored zero, making invalid moves or running out the clock. Given a plan-and-execute harness, the same small models reached 63–82 at about a third of a cent per shift.

Setup

Each scenario is a 24-tick shift with trucks, doors and crews. Delays cost money; the score maps total cost onto 0 (first-come-first-served, no plan) to 100 (the hindsight optimum). In every-tick mode the model picks each action. In harness mode it writes a plan when something changes and the harness executes it.

Score, 0 = no plan · 100 = hindsight optimum
Model picks every move Model plans · harness acts Scripted controller · 75.6
9B open model8B open model31B open modelFrontier models, every tick
0 →63.20 →74.022.1 →81.893.7–99.4
12 fixed scenarios · dc-v1
0255075100

Results are specific to this environment. Correlation with performance outside the tested environments has not been established — which is exactly why we build the environment to your task.

What it means

The gap between “can't do the job” and “close to the expert” was the environment's interface, not the model's size. That is the kind of finding a judge-graded benchmark can't produce: the score moved because the end state moved, and every run behind it replays.

Every-tick small-model results are n = 3 per model. The best harness runs are still below the scripted expert (75.6). The hindsight optimum is a reference point, not a ceiling. Results are specific to this environment.

Data: dock-dc-v1 episodes · available under a data agreementRequest the episodes →

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Same 12 scenarios, same scorer. You get the report, and every run behind it replays.

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