{
  "schema_version": "1.3.0",
  "slug": "which-invariants-prevent-silent-capability-escalation-across-federated-a2a-trust-boundaries",
  "title": "Which invariants prevent silent capability escalation across federated A2A trust boundaries",
  "date_of_record": "2026 November 12",
  "scope": "Applies to cross-org multi-agent federation where an originating agent reaches a remote agent through one or more trust brokers, and where capability attestations and negotiated policies are cached or re-derived at each hop. Does not apply to single-org intra-mesh agent calls where a single policy authority is authoritative, nor to purely stateless request/response tool calls with no delegated authority.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/which-invariants-prevent-silent-capability-escalation-across-federated-a2a-trust-boundaries.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/which-invariants-prevent-silent-capability-escalation-across-federated-a2a-trust-boundaries.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/which-invariants-prevent-silent-capability-escalation-across-federated-a2a-trust-boundaries.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1845,
    "python_slice_tokens": 260,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The failure mode that matters is not *denied* access — denials are loud and are caught by the caller. The failure mode is **silent capability escalation through attestation re-derivation**: a capability that the origin org never granted, or that the remote org never accepted, becomes *effective* because each hop in the federation chain re-evaluates a policy ...",
    "what_was_observed": "A three-org federation: Origin (O) → Broker (B) → Remote (R). O issues an attestation for agent `planner-7` with capability `documents:read` scoped to `tenant=acme`, and explicitly *omits* `documents:export`. B performs policy negotiation with R and, as part of normalization, rewrites the capability set into R's canonical vocabulary. R's vocabulary has no `documents:read`; the closest mapping is `documents:access`, a...",
    "condition_of_validity": "Grant monotonicity holds only under three conditions, all of which must be enforced structurally rather than by convention: 1. **Scope-preserving normalization.** Any vocabulary mapping between orgs must be *scope-preserving or scope-narrowing*. A mapping that cannot express the origin scope must fail closed, not widen. The mapping `documents:read(tenant=acm...",
    "decision_boundary": "The operational decision is where to place the subset check and what to do when it cannot be performed. - If the origin grant is available at the remote (directly or by digest-plus-retrieval), perform the subset check at the remote and fail closed on any capability not covered. This is the strong configuration. - If the origin grant is *not* available at the...",
    "operational_effect": "Enforcing grant monotonicity changes three operational behaviors. First, negotiation failures increase — mappings that previously \"succeeded\" by widening now fail closed, and the failure rate is a direct measure of vocabulary mismatch between orgs. This is desirable and should be monitored as a federation-health metric, not suppressed. Second, cache hit rate..."
  },
  "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": "94098b279666b8e0e1a2f920bce1d207466d7a0ee96161e0cc783004ca236cce",
    "verified_classes": [
      "GrantMonotonicityError",
      "Grant",
      "Attestation"
    ],
    "verified_functions": [
      "verify_hop",
      "negotiate",
      "cache_key",
      "covers"
    ],
    "verified_functions_count": 4,
    "defensive_guards_count": 1,
    "raised_exceptions": [
      "GrantMonotonicityError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "__future__",
      "dataclasses",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}