{
  "schema_version": "1.3.0",
  "slug": "when-must-an-instance-reject-a-delegated-capability-token-despite-a-cryptographically-valid-aaif-delegation-chain",
  "title": "When must an instance reject a delegated capability token despite a cryptographically valid AAIF delegation chain",
  "date_of_record": "2026 November 13",
  "scope": "Applies to agents validating AAIF (Agent Authority & Identity Federation) delegation chains where each link carries a scoped capability attestation signed by the delegating org's issuer. Does not apply to single-org (intra-tenant) delegation where the trust root and the resource owner share one policy authority, nor to bearer tokens whose scope is enforced solely by the resource server.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/when-must-an-instance-reject-a-delegated-capability-token-despite-a-cryptographically-valid-aaif-delegation-chain.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/when-must-an-instance-reject-a-delegated-capability-token-despite-a-cryptographically-valid-aaif-delegation-chain.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/when-must-an-instance-reject-a-delegated-capability-token-despite-a-cryptographically-valid-aaif-delegation-chain.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1543,
    "python_slice_tokens": 309,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "Signature validity and authority validity are orthogonal. An AAIF chain can be *cryptographically intact* — every link's signature verifies against the delegating issuer's published key, every `jti` is unique, every `exp` is in the future — while the *effective authority* it conveys is empty. The failure mode is not forgery; it is **scope intersection collap...",
    "what_was_observed": "In a production federation between three orgs (telemetry provider, broker, analytics consumer), a delegated token passed all structural checks and was accepted by the resource server for 11 days. During that window the consumer read telemetry for `us-east-1` under a purpose outside the original delegator's grant. The audit trail showed every signature valid and every `scope` field a subset of its parent's. The breach...",
    "condition_of_validity": "A delegated capability token is valid **if and only if** for every claim dimension `d` in the union of all dimensions present anywhere in the chain, the leaf's effective value on `d` is within the intersection of all ancestor values on `d`. This requires the validator to: - Enumerate the **union** of claim dimensions across the entire chain, not the intersec...",
    "decision_boundary": "Reject the token when any of the following hold, even though signatures verify: - A claim dimension exists in an ancestor attestation and is absent from a descendant (elision-widening). - The leaf's purpose/audience/principal-class is permitted by its immediate parent but not by the chain root. - The re-delegation right (`can_delegate`) is absent or false on...",
    "operational_effect": "The practical consequence is that **cross-org federation validators must be built as chain-wide conjunctive checkers, not pairwise subset checkers.** Pairwise checking is the default in most AAIF libraries because it is local and cheap; it is unsound across orgs because it cannot see elided dimensions. The mitigation is a two-pass validation: first collect t..."
  },
  "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": "5b642828b19a01fcfa1cc9521105e03812d7d6b1fcd1d64a5569559a0db997aa",
    "verified_classes": [
      "DelegationAttenuationError"
    ],
    "verified_functions": [
      "validate_chain",
      "_is_subset"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 4,
    "raised_exceptions": [
      "DelegationAttenuationError"
    ],
    "sample_fail_closed_invariants": [
      "empty delegation chain"
    ],
    "stdlib_dependencies": [],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}