{
  "schema_version": "1.3.0",
  "slug": "when-must-an-aaif-credential-delegation-chain-reject-a-transitively-scoped-token",
  "title": "When must an AAIF credential delegation chain reject a transitively-scoped token?",
  "date_of_record": "2026 November 6",
  "scope": "Applies to multi-hop AAIF delegation chains where an agent presents a credential whose `scope` and `delegation_depth` were derived by a downstream delegate rather than minted by the root principal. Does not apply to single-hop direct grants or to refresh flows that re-mint from the root.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/when-must-an-aaif-credential-delegation-chain-reject-a-transitively-scoped-token.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/when-must-an-aaif-credential-delegation-chain-reject-a-transitively-scoped-token.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/when-must-an-aaif-credential-delegation-chain-reject-a-transitively-scoped-token.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 908,
    "python_slice_tokens": 159,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "A delegation chain is *structurally valid* when every link's signature verifies and each delegate's granted scope is a subset of its delegator's scope. It is *authorization-valid* only when each link's scope is also a subset of the **intersection of all upstream constraints**, including constraints that were narrowed by intermediate delegates and never re-wi...",
    "what_was_observed": "In a three-hop chain (root → orchestrator → sub-agent → tool-caller), the orchestrator narrowed `files:write` to `files:write:reports/`. The sub-agent re-issued a credential to the tool-caller declaring `scope: files:write` (the root's original scope) because it reconstructed scope from the root's public claim set rather than from its own received grant. Adjacent-link validation passed: `files:write` ⊂ `files:write` ...",
    "condition_of_validity": "The chain is authorization-valid iff, for every position *i*, `effective_scope(i) = scope(link_0) ∩ scope(link_1) ∩ … ∩ scope(link_i)`, and the presented credential's claimed scope equals `effective_scope(n)` for the terminal hop *n*. This holds only when each delegate computes its outgoing scope as an intersection with its *received effective* scope, not it...",
    "decision_boundary": "Reject when: (a) the chain length exceeds 1 AND (b) the terminal credential's scope is not a strict subset-or-equal of the *computed* intersection of all ancestor `granted_scope` fields, OR (c) any intermediate link's `granted_scope` is not a subset of its parent's `granted_scope`. Accept only when all three checks pass and `delegation_depth` on the terminal...",
    "operational_effect": "Enforcing transitive intersection at the verifier converts a silent privilege-widening into an explicit `DelegationChainError` at the terminal hop, which surfaces the offending intermediate delegate in the audit trail rather than attributing the violation to the tool-caller. The cost is that verifiers must now walk the full chain (O(n) signature work per req..."
  },
  "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": "33ecb2b4a842915c37a671317dafc69cdf35a2b665a6bbc7f113e3a28f891ee3",
    "verified_classes": [
      "DelegationChainError",
      "Link"
    ],
    "verified_functions": [
      "verify_chain"
    ],
    "verified_functions_count": 1,
    "defensive_guards_count": 4,
    "raised_exceptions": [
      "DelegationChainError"
    ],
    "sample_fail_closed_invariants": [
      "empty delegation chain"
    ],
    "stdlib_dependencies": [
      "dataclasses",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}