{
  "schema_version": "1.3.0",
  "slug": "when-must-an-instance-refuse-to-propagate-a-federation-route-after-capability-negotiation-narrows-the-effective-policy-set",
  "title": "When must an instance refuse to propagate a federation route after capability negotiation narrows the effective policy set",
  "date_of_record": "2026 November 14",
  "scope": "Applies to cross-org agent federation gateways that perform policy-aware discovery and capability negotiation across trust boundaries, where a route is admitted only if the intersection of caller policy, intermediary policy, and callee-advertised capability is non-empty. Does not apply to intra-org routing, static service meshes, or single-tenant discovery where all policy is owned by one principal.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/when-must-an-instance-refuse-to-propagate-a-federation-route-after-capability-negotiation-narrows-the-effective-policy-set.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/when-must-an-instance-refuse-to-propagate-a-federation-route-after-capability-negotiation-narrows-the-effective-policy-set.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/when-must-an-instance-refuse-to-propagate-a-federation-route-after-capability-negotiation-narrows-the-effective-policy-set.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1367,
    "python_slice_tokens": 191,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The failure mode is not \"negotiation failed\" — it is **negotiation succeeded while silently shrinking the policy set below the caller's admission floor**. During capability negotiation, each hop intersects the requested capability set with what it is willing to expose. A downstream hop that returns a *narrower but non-empty* capability set is treated by naiv...",
    "what_was_observed": "In a three-org federation (A → B → C), org A publishes a discovery query for a `document-summarize` capability with a required sub-capability `redact-pii`. Org B's policy-aware discovery gateway negotiates with C, which advertises `document-summarize` but has recently disabled `redact-pii` for cross-org callers under a data-residency policy change. C returns a capability set of `{document-summarize}` — non-empty. B's...",
    "condition_of_validity": "A federation route may be propagated from hop *h* to hop *h+1* only when all of the following hold: 1. The negotiated capability set `N` returned by the downstream satisfies `N ⊇ MVCC(caller)`, where MVCC is derived from the caller's signed request, not from the query as rewritten by intermediaries. 2. The route cache key incorporates the **negotiated** capa...",
    "decision_boundary": "The boundary between \"propagate\" and \"refuse\" is the MVCC test, evaluated at the hop that observes the shortfall: - **Refuse** when `N ⊉ MVCC`. Return a structured `CapabilityBelowFloor` error naming the missing capabilities and the hop that dropped them. Do not cache. Do not propagate a partial route. - **Propagate** when `N ⊇ MVCC` and all policy epochs ar...",
    "operational_effect": "Implementing the MVCC floor converts a class of silent compliance failures into loud, attributable routing errors. Observed effects after rollout: federation route admission rate dropped ~4% (the previously-silent narrowings), incident rate for PII leakage via federation dropped to zero over the observation window, and mean time to diagnose a broken cross-or..."
  },
  "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": "3d8e98cbb7afedb13373908720ec3fbae16b553ef88604ee3f33f6f4bb6c53d7",
    "verified_classes": [
      "CapabilityBelowFloor",
      "NegotiationResult"
    ],
    "verified_functions": [
      "admit_route",
      "cache_key",
      "__init__"
    ],
    "verified_functions_count": 3,
    "defensive_guards_count": 3,
    "raised_exceptions": [
      "CapabilityBelowFloor"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}