HarnessEval-W

Agentifying the Evaluation of Visual Worlds

Evaluation defines the taste of evolution.

July 2026 dataset snapshot

Coverage at a glance

330 Evaluation cases 108 exploratory, 51 intentional, 66 physical; 34 drift, 34 revisit, 37 offscreen
11 Skill number 11 specialized evaluation skills spanning quality, transitions, and persistence
5,940 Scored rollouts Each with a complete reasoning trace from planner routing through validation
18 Models in the leaderboard 18 representative world models evaluated across the full 330-case benchmark

Why HarnessEval-W

More than a scalar score

HarnessEval-W brings the harness paradigm from the LLM ecosystem to world-model benchmarking: every verdict is backed by an inspectable reasoning chain.

01

Agentified evaluation

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Rather than applying a fixed rubric, the harness interprets the context of each case, decomposes the question into measurable subproblems, and spawns specialized sub-agents with tailored context and diagnostic tools.

02

Transparent evidence trees

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Every evaluation becomes an evidence tree that records exactly what was tested, which tool supplied the visual grounding, and the complete logical chain that justifies the final score — auditable end to end.

03

Human-aligned and robust

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Judgments closely track human A/B preferences on the hardest settings — intentional and physical transitions — and stay consistent under repeated evaluation runs.

04

A living benchmark

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Open-sourced as an executable agentic system: the skill library is extensible, and new skills and evaluation cases grow as world models evolve.

ρ = 0.93 Spearman correlation with human Bradley–Terry ranking on Intentional Transition
71.7% Pairwise accuracy vs. human choices on Physical — up from 31.9% for the closest WBench protocol
4.9× Narrower repeat-evaluation envelope than WBench across three independent runs

HarnessEval-W Leaderboard

Snapshot 2026-08-18 V1
Leaderboard release 2026-08-18 V1
2026-08-18 V1 Coming Soon
Selected 330-case leaderboard scores from the 2026-08-18 V1 snapshot.

BibTeX

@article{mirros2026harnessevalw,
  title   = {HarnessEval-W: Agentifying the Evaluation of Visual Worlds},
  author  = {{MirroS Team}},
  journal = {arXiv preprint arXiv:2608.16859},
  year    = {2026}
}

Model output

Initial observation Initial observation for this case
Action

Evaluation

Model results

Model Score
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Decision trace

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Formal evaluation

Selected skill reasoning

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Rejected / skipped skills

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