{
  "id": "qk-fc2-cache",
  "change_class": "exact",
  "hypothesis": "A 512 MiB free-allocator cache can remove the small physical-footprint regression of the fused path while retaining its speed. It cannot reduce live model memory.",
  "candidate_config": {
    "kernel": "metal-exact",
    "tune_matmul": true,
    "allocator_cache_gb": 0.5
  },
  "control_allocator_cache_gb": 1,
  "reject_if": "Full declared quality/timing/memory contract fails; do not change gates or pool samples from other campaigns.",
  "screen_before_full": "Real compiled block at both cache limits; no GPU concurrency.",
  "bounded_search": "One additional full-image finalist at most, within original 120-minute and 5GiB global budget. No inference-code edits until current benchmark completes.",
  "result": {
    "decision": "rejected-at-block-screen",
    "evidence": "reports/optimization-r3/cache-screen.json",
    "slowdown_pct": 1.6453551990850412,
    "cache_1_peak_physical_bytes": 2387051720,
    "cache_05_peak_physical_bytes": 2581791944,
    "accuracy": "all BF16 block outputs identical",
    "scope": "Isolated real first block; does not establish whole-image behavior. No allocator-limit change shipped."
  }
}