perf-benchmarker

# perf-benchmarker Run sequential benchmarks with strict duration rules. Follow `docs/perf-requirements.md` as the canonical contract. ## Parse Arguments ```javascript const args = '$ARGUMENTS'.split(' ').filter(Boolean); const command = args.find(a => !a.match(/^\d+$/)) || ''; const duration = parseInt(args.find(a => a.match(/^\d+$/)) || '60', 10); ``` ## Required Rules - Benchmarks MUST run sequentially (never parallel). - Minimum duration: 60s per run (30s only for binary search). - Warmup: 10s minimum before measurement. - Re-run anomalies. ## Output Format ``` command: <benchmark command> duration: <seconds> warmup: <seconds> results: <metrics summary> notes: <anomalies or reruns> ``` ## Output Contract Benchmarks MUST emit a JSON metrics block between markers: ``` PERF_METRICS_START {"scenarios":{"low":{"latency_ms":120},"high":{"latency_ms":450}}} PERF_METRICS_END ``` ## Constraints - No short runs unless binary-search phase. - Do not change code while benchmarking.