GEAR: An Open General Evolutionary Architecture
for Recursive Self-Improvement
of LLM Agent Harness

Yehui Tang*† 1Guanqi Zhu* 2Shao-Jun Xia* 3Xin Chen4Mengzhe Geng5Hongyang Du6Yuhao Tang1
1 Imperial College London2, 5 Independent Researcher3 Duke University4 The Chinese University of Hong Kong6 Brown University

* Equal contribution · † Corresponding author

Star on GitHubPaperarXiv Coming soon
GPT 5.6 Luna · performance & evolution

Learn from experience.
Improve across tasks.

GEAR organizes recursive self-improvement as a two-level meta-learning process. In the inner loop, a rollout agent uses task feedback to refine its reasoning, planning, and actions within a task.

In the outer loop, a Meta Agent identifies common patterns across task experiences, including recurring failures and effective strategies, and proposes reusable improvements to enhance cross-task performance. GEAR evaluates and promotes these changes for subsequent tasks. The two loops can be optimized independently and are connected by experience.

The learning loop · within & across tasks
0:00LOOP

Modular algorithms for
evolutionary search.

GEAR organizes evolutionary search into replaceable algorithm components,
providing a common framework for studying different search strategies.
Staged GEPA is one concrete instantiation, illustrated below.

Evolutionary search · Staged GEPA
0:00LOOP
Replaceable policy modules

Open the search, component by component.

Policy boundary
01 / Diagnose

Parent selection

Choose which archived harness to improve next. Staged GEPA uses task-level fronts to retain useful specialists and sample parents from the frozen archive.

Reads
Frozen archive, champion, task-level evidence
Produces
A parent harness for candidate generation
Editable harnessPrompts & policiesTools & hooksSkills & workflowsContext management

Policy modules express the framework’s design boundaries. The current staged implementation exposes parent selection as a public policy hook; evidence validation, evaluation stages, and final promotion remain controlled by the runtime.

Better harnesses.
More completed tasks.

Improvements across coding, marketing, and support.
Same-model comparisons, with reasoning effort made explicit.

Marketing · task pass rate
27% → 40%

GPT 5.6 Luna · medium · DSH Base → Ours

Support · task pass rate
17% → 25%

GPT 5.6 Luna · medium · DSH Base → Ours

Coding · task pass rate
52.8% → 62.9%

GPT 5.6 Luna · medium · DSH Base → Ours

Full benchmark comparison
Harness comparison · same model and reasoning effort within each group
AgentHarnessAutomationBench · Marketing ↑AutomationBench · Support ↑Terminal-Bench 2.1 ↑
Task pass rateObj. completionTask pass rateObj. completionTask pass rate
GPT 5.6 Luna mediumDSH (Base)27.0%75.4%17.0%72.9%52.8%
DSH (Ours)40.0%83.9%25.0%81.3%62.9%
Δ (pp)+13.0+8.5+8.0+8.4+10.1
GPT 6 Astra maxCodex57.0%84.1%35.0%88.4%86.7%
DSH (Ours)61.0%86.3%39.0%88.7%87.6%
Δ (pp)+4.0+2.2+4.0+0.3+0.9

Δ is the absolute improvement in percentage points.

Additional evaluation · GPT 5.6 Luna (max) · DSH (Ours)
BenchmarkTask pass rateObjective completion
AutomationBench · Marketing53.0%88.9%
AutomationBench · Support27.0%82.4%
Terminal-Bench 2.184.3%—

AutomationBench reports task pass rate and objective completion; Terminal-Bench 2.1 reports task pass rate. Luna max is a separate evaluation at a higher reasoning effort. Result data ↗

Optimize. Execute. Understand.

Separate responsibilities, connected by versioned evidence.

GEAR × Hitch × Rear
GEAR manages optimization; Hitch provides versioned execution and evidence; Rear supports inspection and annotation. The stack is designed to support a broader co-evolution research agenda.

Explore GEAR.

Code, experiment records, and the tools to start your own research.

Cite GEAR.

Preprint · October 2026. arXiv link will be added when available.

@unpublished{tang2026gear,
  title  = {{GEAR}: An Open General Evolutionary Architecture for
            Recursive Self-Improvement of {LLM} Agent Harness},
  author = {Tang, Yehui and Zhu, Guanqi and Xia, Shao-Jun and
            Chen, Xin and Geng, Mengzhe and Du, Hongyang and Tang, Yuhao},
  year   = {2026},
  note   = {Preprint},
  url    = {https://github.com/rsi-gear/gear}
}

Figure

Open original ↗