Captures medians of 5 runs for multitab and render-churn so tonight's
wins can't silently regress.
idle-cost is deliberately NOT gated. Its render attribution and idle
commit rate are trustworthy and are what the scenario exists for, but the
drag fps it reports (~0.6fps, p95 814ms) contradicts a direct
single-clock probe of the same gesture on the same build (57fps). I ruled
out sash selection, tile setup, render-counter residue, and a 20s soak,
and could not explain the gap — so the metric ships as a report, not a
gate. Gating CI on a number I can't defend would either fire on a phantom
or mask a real stall.
tier: 'report' is outside GATED ('ci','cold'), so the scenario still runs
and prints but neither compares nor writes a baseline.