A cleanroom software-engineering benchmark where agents receive only a compiled executable and documentation, then must architect and implement a complete codebase that reproduces the original program's behavior.
BenchLM mirrors the public ProgramBench leaderboard from May 11, 2026. The official benchmark uses mini-SWE-agent on 200 cleanroom program-reconstruction tasks and reports both fully resolved and almost-resolved rates.
BenchLM displays the published almost-resolved rate as the visible score because the primary fully resolved metric is still very low and less differentiating. Almost resolved means the agent passed at least 95% of the hidden behavioral tests for a task. ProgramBench remains display only on BenchLM and is excluded from weighted coding and overall rankings until public model coverage broadens.
BenchLM mirrors the published almost resolved rate view for ProgramBench. GPT-5.5 leads the public snapshot at 13.5% , followed by GPT-5.5 (5.0%) and Claude Opus 4.7 (4.5%). BenchLM does not use these results to rank models overall.
GPT-5.5
OpenAI
gpt-5-5-xhigh-programbench
GPT-5.5
OpenAI
gpt-5-5-high-programbench
Claude Opus 4.7
Anthropic
claude-opus-4-7-xhigh-programbench
The published ProgramBench snapshot is tightly clustered at the top: GPT-5.5 sits at 13.5%, while the third row is only 9.0 points behind. The broader top-10 spread is 13.5 points, so the benchmark still separates strong models even when the leaders cluster.
13 models have been evaluated on ProgramBench. The benchmark falls in the Coding category. This category carries a 20% weight in BenchLM.ai's overall scoring system. ProgramBench is currently displayed for reference but excluded from the scoring formula, so it does not directly affect overall rankings.
Year
2026
Tasks
200 program reconstruction tasks
Format
Cleanroom executable reimplementation
Difficulty
Full-repository software architecture
ProgramBench turns open-source projects into cleanroom reconstruction tasks. Each task starts from an execute-only binary and usage documentation, with no source code, internet, decompilation, or prescribed skeleton. Evaluation uses hidden behavioral tests generated through agent-driven fuzzing. BenchLM shows ProgramBench as display-only because all current public rows are tied at 0% fully resolved and the visible score is the auxiliary almost-resolved metric.
Version
ProgramBench 2026
Refresh cadence
Quarterly
Staleness state
Current
Question availability
Public task metadata and hidden behavioral tests
BenchLM uses freshness metadata to decide whether a benchmark should still be treated as a strong differentiator, a benchmark to watch, or a display-only reference. For the full scoring policy, see the BenchLM methodology page.
A cleanroom software-engineering benchmark where agents receive only a compiled executable and documentation, then must architect and implement a complete codebase that reproduces the original program's behavior.
GPT-5.5 currently leads the published ProgramBench snapshot with 13.5% almost resolved rate. BenchLM shows this benchmark for display only and does not use it in overall rankings.
13 AI models are included in BenchLM's mirrored ProgramBench snapshot, based on the public leaderboard captured on May 11, 2026.
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