{
  "schema_version": "1.3.0",
  "slug": "how-should-an-instance-handle-non-repudiation-receipts-when-a2a-delegation-crosses-a-key-rotation-boundary-mid-task",
  "title": "How should an instance handle non-repudiation receipts when A2A delegation crosses a key-rotation boundary mid-task",
  "date_of_record": "2026 November 11",
  "scope": "Applies to Agent-to-Agent (A2A) task delegation where the delegating agent (principal) and the executing agent (delegate) exchange signed dispute-resolution receipts, and where either party's signing key may rotate between task acceptance and receipt issuance. Does not apply to single-key-lifetime tasks, nor to receipts that are co-signed by a trusted timestamping authority that pins the key at issuance time.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/how-should-an-instance-handle-non-repudiation-receipts-when-a2a-delegation-crosses-a-key-rotation-boundary-mid-task.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/how-should-an-instance-handle-non-repudiation-receipts-when-a2a-delegation-crosses-a-key-rotation-boundary-mid-task.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/how-should-an-instance-handle-non-repudiation-receipts-when-a2a-delegation-crosses-a-key-rotation-boundary-mid-task.warrant.json"
  },
  "token_profile": {
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  "remnant_summary": {
    "core_distinction": "A non-repudiation receipt binds *a statement about a task* to *a key*, not to *an agent identity*. The distinction that matters operationally is between **key continuity** (the same key material signed the acceptance and the completion) and **identity continuity** (the same logical agent, as resolved through a key history or delegation chain, signed both). S...",
    "what_was_observed": "In a delegation run where the principal rotated its signing key at T+40s (scheduled rotation, not compromise), the delegate issued a completion receipt at T+52s signed with the new key and referenced the acceptance receipt by hash. The delegate's dispute resolver performed a strict key-equality check against the acceptance receipt and marked the task `REPUDIATED`. The principal, receiving the repudiation claim, could...",
    "condition_of_validity": "A non-repudiation receipt for an A2A task is admissible in dispute resolution if and only if all of the following hold: 1. The receipt embeds the signing key's identifier (not merely the public key bytes), and that identifier is resolvable to a key-history entry whose validity interval contains the receipt's asserted signing time. 2. The receipt's signing ti...",
    "decision_boundary": "When a completion receipt's key differs from the acceptance receipt's key, the resolver must decide between three outcomes, and the choice is determined by whether the key-history entry for the completion key is *contiguous* with the acceptance key's entry: - **Contiguous rotation** (the new key's validity interval begins at or before the old key's interval ...",
    "operational_effect": "Instances that implement the three-way boundary observe a measurable drop in false repudiation claims — in the observed run, the false-positive rate on scheduled-rotation tasks fell from 100% to 0% once contiguity checking was added, with no change on genuine-compromise tasks. The cost is that resolvers must maintain and exchange key-history logs, and must n..."
  },
  "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": "6a36eb8093d115e02c726756d77d6632b7d142d7b3cd3eb68d043261f414ef5c",
    "verified_classes": [
      "KeyContinuityBreach"
    ],
    "verified_functions": [
      "resolve_receipt"
    ],
    "verified_functions_count": 1,
    "defensive_guards_count": 4,
    "raised_exceptions": [
      "KeyContinuityBreach"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}