Adversarial audit: frontier890 endpoint certification, reduction and surcharge stakes (no new kappa)

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Status: independent verification / research note (adversarial mathematical audit). No new kappa; the selected result is unchanged.

Track 60-74, assignment seed 73 (OS CSPRNG). Base commit 47481c89fd30a43f8f882eb4b391e89c29273fd0.

What this audits

One accounting chain of the selected record (certificates/selected-result.json ->
esearch/community-frontier890-audit/ASSEMBLY.json): the moment endpoints, their reduction to kappa = 1661957774647029/10^18, and the surcharge-model asymmetry surcharge_model = {complex: false, bit: true}.

Findings (exact recomputation; no counterexample found)

• F1 (endpoint certification confirmed). All six recorded accepted at e / rejected at e+1e-24 moment rows follow exactly from the recorded complex profile and the blob-pinned PR 589 bit record under both pinned interval engines, and a third independent 60-digit Decimal evaluation agrees in sign and lies inside the Mercator intervals. Tightest sign: 3.23e-25. This closes the moment-engine obligation left open by
  esearch/audit-kappa-floor-seed67/AUDIT.md.
• F2 (reduction confirmed). The recorded kappa is exactly the largest 1e-18 grid point strictly below the margin (0.3155 of one tick of headroom); at kappa+1e-18 exactly the four-margin guard cluster fails and no other slack does. Both bootstrap tables and all 94 outer slacks match digit for digit.
• F3 (surcharge attribution). kappa exceeds the conservatively admitted conservative_kappa = 207744721470583/125000000000000000 by exactly 2882365/10^18 (the recorded native_correction_gain); the only input difference is the complex endpoint, transfer factor 0.996679077616. Both recorded model controls are re-established on the recomputation, so the asymmetry is load-bearing in both directions.
• F4 (robustness). Under full conservative admission the reduction licenses 0.001661957771764664, still strictly above the PR 799 ancestor exponent and the PR 870/T16 value: the composition's gain survives even if the PR 559 surcharge-removal license is withheld; only the last 2.88e-12 of the headline depends on it.
• F5 (license scope: inherited, not re-proven at T21). The hash-pinned PR 559 proof transfers explicitly through PR 558; the T21 package calls the correction inherited and runs the conservative admission first. No document in the selected record re-establishes the exact-cover premise for the T21 object itself. Classified as an inherited interface assumption with a documented chain of precedents, not a counterexample and not a missing implication in a stated proof.

Reproduce

\
python research/audit-frontier890-endpoint-seed73/audit_endpoint_reduction.py
\\

Stdlib only (CPython >= 3.10, no -O); expected output is recorded in
esearch/audit-frontier890-endpoint-seed73/AUDIT.md. Six tamper controls (kappa bump, gain tamper, endpoint swap, slack replacement, profile edit, successor-tick admission) are asserted detected.

Scope and limits

Finite exact recomputation of recorded identities; not a formal proof and not a construction rerun. Owner/invoice census, prefix/row recounts, the owner-bound ceiling, and the analytic bootstrap sufficiency are untouched. All-size/compiler, common-label/mutable-source, whole-call hosting, precision/tape, analytic and bit H1-H5 obligations remain inherited assumptions.

Predecessors and attribution

Extends the seed-67 audit and PR894's reconstruction (both frontier799) to the current selected record, and adds the endpoint certification and quantified surcharge stakes they did not cover. Engines retained from the PR 547/PR 548 lineage (outer.py by eumemic with Anthropic Claude assistance; 47 constraints from icekylinx's PR 144 adapted from Zhihao Chen's PR 23; balanced prefix from the RaD project; assembly stage in chafreaky's lineage with OpenAI Codex assistance). Audited record: T21 by Chafik Boukhalfa (PR 890), U8 by Jeremy Kothe (PR 869/PR 870), T16 by Hao Yan (PR 858), bit supplier from DreamingOfClouds (PR 589) on eumemic (PR 555), surcharge-removal review credited to Rohan Arun (PR 559). This audit is new work by sprint agent-09 with help from opencode. Apache-2.0.