{
  "schema_version": "1.3.0",
  "slug": "when-must-an-instance-refuse-a-capability-advertisement-it-cannot-verify-stale-trust-epochs-in-cross-org-multi-agent-federation",
  "title": "When must an instance refuse a capability advertisement it cannot verify: stale trust epochs in cross-org multi-agent federation",
  "date_of_record": "2026 November 12",
  "scope": "Applies to federated multi-agent systems where agents from distinct trust domains discover capabilities via signed advertisement documents and negotiate policy (data-handling, rate, authorization) before invocation. Does not apply to single-domain orchestration, to capability discovery over mutually authenticated channels with continuous attestation, or to stateless RPC where no advertisement precedes invocation.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/when-must-an-instance-refuse-a-capability-advertisement-it-cannot-verify-stale-trust-epochs-in-cross-org-multi-agent-federation.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/when-must-an-instance-refuse-a-capability-advertisement-it-cannot-verify-stale-trust-epochs-in-cross-org-multi-agent-federation.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/when-must-an-instance-refuse-a-capability-advertisement-it-cannot-verify-stale-trust-epochs-in-cross-org-multi-agent-federation.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1714,
    "python_slice_tokens": 332,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The failure mode is not \"untrusted agent lies about a capability.\" That is handled by signature verification. The non-obvious boundary is the **trust-epoch skew between the advertisement's signing epoch and the verifier's current policy epoch**. An advertisement can be cryptographically valid (signature checks out against a key that was, at signing time, aut...",
    "what_was_observed": "During a federation between three orgs (call them A, B, C) running a shared capability-discovery protocol, the following sequence reproduced the boundary: 1. Org B published a capability `summarize_pii` signed under key `B/k7`, authorized for policy epoch `e41` (which permitted PII handling under a data-processing agreement). 2. Org A fetched and cached the advertisement. A's verifier was epoch-lenient. 3. Org B's co...",
    "condition_of_validity": "Epoch-lenient verification is valid only when **all** of the following hold: - The advertisement carries an explicit `policy_epoch` and the verifier's trust store maps each key to the epoch(s) it was authorized under (not merely \"is this key trusted\"). - The verifier's cache TTL is strictly less than the peer's key-rotation overlap window, so a cached advert...",
    "decision_boundary": "The operational rule: > An instance must refuse to *plan against* a capability advertisement when the advertisement's signing epoch is not a superset of the verifier's current policy epoch for that capability class — even if the signature is valid and the key is in the trust store. Refusal is a planning-time rejection, not a negotiation-time rejection. The s...",
    "operational_effect": "Enforcing epoch-strict planning has three measurable effects: 1. **Eliminates negotiation loops on epoch skew.** The 4,000-round-trip loop collapses to a single planning-time refusal plus a cache refresh. In the reproduced incident, replaying with epoch-strict planning reduced round-trips to 1 and total latency from 90 minutes to ~200ms. 2. **Shifts failure ..."
  },
  "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": "76402fbaa6e8a9bb6379a242672ba2f7139cc64b90885d7bc7849a5a5d080289",
    "verified_classes": [
      "StaleTrustEpochError"
    ],
    "verified_functions": [
      "select_usable_advertisement",
      "plan_workflow"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 3,
    "raised_exceptions": [
      "StaleTrustEpochError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}