{
  "schema_version": "1.3.0",
  "slug": "which-invariants-prevent-a-delegated-authorization-chain-from-silently-widening-scope-at-the-second-hop",
  "title": "Which invariants prevent a delegated authorization chain from silently widening scope at the second hop",
  "date_of_record": "2026 November 12",
  "scope": "Applies to AAIF-style agent identity attestation where a root principal issues a verifiable credential (VC) to agent A, and A delegates a derived credential to agent B via a chain of attenuation. Does not apply to single-hop issuance where the root principal directly signs the leaf credential, nor to bearer-token systems without cryptographic delegation.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/which-invariants-prevent-a-delegated-authorization-chain-from-silently-widening-scope-at-the-second-hop.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/which-invariants-prevent-a-delegated-authorization-chain-from-silently-widening-scope-at-the-second-hop.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/which-invariants-prevent-a-delegated-authorization-chain-from-silently-widening-scope-at-the-second-hop.warrant.json"
  },
  "token_profile": {
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    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "A delegated authorization chain is *sound* when every hop strictly attenuates the capability set: the child credential's authority set is a subset of the parent's, and the child's subject is bound to the parent's subject through a signed delegation proof. A chain is *silently widened* when the child credential is syntactically valid, verifies against the roo...",
    "what_was_observed": "In a multi-hop AAIF deployment, a root principal issued a VC to a scheduling agent with scope `{\"actions\": [\"read:calendar\", \"write:calendar\"], \"resources\": [\"cal:team-a/*\"]}`. The scheduling agent delegated to a sub-agent a credential whose structured `resources` claim was `[\"cal:team-a/alice\"]` — properly narrowed — but whose legacy `scope` string field, retained for backward compatibility with an older verifier, w...",
    "condition_of_validity": "The chain is sound only when all of the following hold simultaneously at every hop: 1. **Total attenuation.** For every representation of scope in the parent (structured claims, string fields, extension fields, header-derived scopes), the child's corresponding representation must be a subset. Attenuation is a conjunction over representations, not a disjuncti...",
    "decision_boundary": "When a verifier encounters a credential chain, the decision boundary is between *verifying the chain* and *authorizing the request*. These must be separate decisions with separate failure modes: - If signatures verify but attenuation cannot be proven over all representations → reject with a chain-integrity error. Do not fall back to \"trust the root, ignore t...",
    "operational_effect": "Enforcing total attenuation and parent commitment converts silent widening into loud, attributable failures. In the deployment above, adding a parent-digest commitment to delegation proofs and a representation-completeness check to the attenuation logic caused the sub-agent's malformed delegation to fail at issuance rather than at the downstream resource ser..."
  },
  "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": "a0fff8200126b85cd4913f753b3df8dbc41b812d1133f4377450e68f38b502f0",
    "verified_classes": [
      "DelegationWideningError",
      "Credential"
    ],
    "verified_functions": [
      "_parse_scope_string",
      "_subset",
      "verify_attenuation",
      "verify_chain",
      "digest"
    ],
    "verified_functions_count": 5,
    "defensive_guards_count": 4,
    "raised_exceptions": [
      "DelegationWideningError"
    ],
    "sample_fail_closed_invariants": [
      "delegation proof is not bound to this parent credential",
      "structured actions not represented in scope_string; representation collapse detected",
      "empty chain"
    ],
    "stdlib_dependencies": [
      "dataclasses",
      "hashlib",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}