iter 16 — end-to-end verdict determinism

SURVIVES 2026-07-10 · the assembled machine verified as a pure function of its inputs · clean 1/3

Claim under attack (assumed true only to destroy it)

Every hardening layer landed by this campaign is deterministic BY DESIGN — sha-derived seeds, Knuth-hash tie-breaks, content-addressed identity keys, fixed replicate streams, linspace downsampling — but the assembled whole was never verified, and three past findings (iter 3 order-dependence, iter 6 MC knife-edges, iter 11 partition selection) were precisely reproducibility-class defects. A non-deterministic verdict pipeline would invalidate the audit trail itself.

Attack construction

Frozen feed: a replay cache wraps probe.fetch_cell — one real fetch per cell, deep copies replayed to both runs (the claim is about COMPUTE; the live table accretes rows).
Leg 1: aggregate_worst_cell run TWICE (2 kernels × 2 cells × 40k bars) — the two verdict JSON files byte-compared. F1: any byte diff.
Leg 2: evaluate_pooled run TWICE on identical in-memory matrices (do_xi=True, seed=0) — record-compared. F2: any field diff.

Result

Check	Result
Leg 1 — worst-cell path (the promotion gate), double run	byte-identical verdict JSON
Leg 2 — pooled path (binding ρ + advisory ξ), double run	record-identical outputs

Evidence

File	What
a16_determinism_attack.py	The attack — falsifiers pre-declared in-file; replay-cache construction documented.
a16_results.json · a16_run1.json / a16_run2.json	Falsifier evaluation + the two byte-identical verdict files (diffable by anyone).
a16_stderr.log	Run log under the 2 CPU / 2 GB scope.
regression_tests/test_a16_determinism.sh	Permanent regression test — re-runs the double-run, asserts SURVIVES.

Consequence

The verdict machinery — with all fifteen iterations of hardening assembled — is proven a pure function of its inputs at byte granularity. Combined with the identity-key order-invariance (iter 3/8) and the frozen bands, every verdict in the terminal head-to-head will be exactly reproducible from its input snapshot. Clean rounds: 1 of 3.

iter 16 · verdict determinism · verdict SURVIVES · one atomic commit: iter 16: verdict determinism — SURVIVES · append-only.