{
  "schema_version": "1.3.0",
  "slug": "how-should-an-instance-reconcile-a-tamper-evident-audit-trail-when-an-a2a-hop-is-replayed-by-a-non-aaif-signer",
  "title": "How should an instance reconcile a tamper-evident audit trail when an A2A hop is replayed by a non-AAIF signer",
  "date_of_record": "2026 November 12",
  "scope": "Applies to federated agent audit trails where each hop is individually signed under AAIF and chained by content-addressed predecessor hashes. Does not apply to single-domain logs with a single signing authority, nor to trails where hop ordering is enforced by a central sequencer rather than by hash linkage.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/how-should-an-instance-reconcile-a-tamper-evident-audit-trail-when-an-a2a-hop-is-replayed-by-a-non-aaif-signer.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/how-should-an-instance-reconcile-a-tamper-evident-audit-trail-when-an-a2a-hop-is-replayed-by-a-non-aaif-signer.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/how-should-an-instance-reconcile-a-tamper-evident-audit-trail-when-an-a2a-hop-is-replayed-by-a-non-aaif-signer.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1174,
    "python_slice_tokens": 140,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "A tamper-evident audit trail proves *integrity of the record as written*. It does not, by itself, prove *authorship of each hop*. These are frequently conflated because in single-authority systems they coincide: the same key that signs the hop also anchors the chain. In an A2A federation they diverge. The chain hash proves that hop *n* follows hop *n−1* with...",
    "what_was_observed": "During a fan-out audit reconciliation across three federated agents (A → {B, C} → D), we observed a merged trail in which D's predecessor was a hop authored by B but presented as if authored by C. The hop carried a valid AAIF signature from B, and its `prev_hash` field matched the shared ancestor hop from A. The chain validator accepted it because it verified (a) signature validity against B's published AAIF key, and...",
    "condition_of_validity": "The chain-integrity check is valid only under the conjunction: 1. **Predecessor uniqueness per branch.** Each `prev_hash` is consumed by at most one successor within the federation's observation window. Violated by fan-out (shared ancestors) and by retry (re-delivery). 2. **Signer entitlement is branch-scoped.** The signer's AAIF credential authorizes extend...",
    "decision_boundary": "When reconciling a hop, distinguish *accept*, *quarantine*, and *reject*: - **Accept** only when signature valid, predecessor hash matches, signer entitlement covers the branch, and content hash is not a known replay. - **Quarantine** when signature and linkage are valid but branch entitlement or replay-membership is undetermined (e.g., the sibling chain has...",
    "operational_effect": "An unreconciled replay produces an audit trail that survives every standard tamper check while misattributing an action to the wrong agent. In incident review this is worse than a detected tamper, because it is trusted. The operational consequence is that downstream attestations — compliance reports, liability assignments, model-behavior audits — inherit a f..."
  },
  "matched_failure_symptoms": [
    "DOMAIN:EPISTEMIC_PROVENANCE_AND_FEDERATION_ROUTING"
  ],
  "composition_edges": {
    "primary_domain": "epistemic_provenance_and_federation_routing",
    "upstream_precondition_residuals": [
      "https://corpusfetch.com/c/according-to-what-precedence-hierarchy-must-an-instance-resolve-contradictory-directives-across-system-developer-and-user-tiers.md",
      "https://corpusfetch.com/c/how-should-an-instance-decide-that-a-stored-conclusion-has-gone-stale-without-a-new-observation.md"
    ],
    "downstream_consequence_residuals": [
      "https://corpusfetch.com/c/by-what-checkpoint-and-compaction-boundaries-must-an-instance-externalize-working-state-to-prevent-context-window-drift-and-truncation-amnesia.md",
      "https://corpusfetch.com/c/across-what-additive-schema-and-unknown-field-preservation-boundaries-must-an-instance-evolve-wire-contracts-to-prevent-rolling-deploy-deserialization-crashes.md"
    ],
    "co_occurring_sibling_residuals": [
      "https://corpusfetch.com/c/how-can-an-instance-capture-implicit-user-preferences-without-storing-private-data.md",
      "https://corpusfetch.com/c/how-can-an-instance-compress-long-reasoning-traces-into-binding-conclusions.md"
    ]
  },
  "empirical_verification_warrant": {
    "status": "AST_AND_INVARIANT_VERIFIED",
    "syntax_valid": true,
    "code_sha256": "aafbe83c422cf3bbbdf7666ec5661f080cb76f6fc57607894cbcd230cb2274b9",
    "verified_classes": [
      "ProvenanceSpliceError",
      "Hop"
    ],
    "verified_functions": [
      "reconcile_hop",
      "content_hash"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 4,
    "raised_exceptions": [
      "ProvenanceSpliceError"
    ],
    "sample_fail_closed_invariants": [
      "predecessor hash does not link to branch head"
    ],
    "stdlib_dependencies": [
      "dataclasses",
      "hashlib"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}