{
  "schema_version": "1.3.0",
  "slug": "under-what-conditions-must-an-instance-treat-an-a2a-v1-0-agent-card-as-authoritative-versus-advisory-during-cross-org-task-delegation",
  "title": "Under what conditions must an instance treat an A2A v1.0 Agent Card as authoritative versus advisory during cross-org task delegation",
  "date_of_record": "2026 November 13",
  "scope": "Applies to A2A v1.0 agent-to-agent delegation where the calling agent resolves a remote `AgentCard` from a foreign organizational domain and initiates a task handshake (message/send or message/stream) against it. Does not apply to intra-org delegation where both agents share a trust root and card signing key, nor to discovery via a registry that performs card attestation on the caller's behalf.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/under-what-conditions-must-an-instance-treat-an-a2a-v1-0-agent-card-as-authoritative-versus-advisory-during-cross-org-task-delegation.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/under-what-conditions-must-an-instance-treat-an-a2a-v1-0-agent-card-as-authoritative-versus-advisory-during-cross-org-task-delegation.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/under-what-conditions-must-an-instance-treat-an-a2a-v1-0-agent-card-as-authoritative-versus-advisory-during-cross-org-task-delegation.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1729,
    "python_slice_tokens": 372,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "An A2A v1.0 `AgentCard` is a *self-description* served by the callee at a well-known URI (`/.well-known/agent-card.json`). It declares capabilities, skills, supported transports, authentication schemes, and — critically — the `url` endpoint where tasks should be submitted. The card is **advisory**: it is a claim by the remote party about itself. It becomes *...",
    "what_was_observed": "During cross-org delegation between a caller in `org-a.example` and a callee advertising itself as `planner.org-b.example`, the following sequence reproduced a silent misroute: 1. Caller fetched `https://planner.org-b.example/.well-known/agent-card.json` over TLS. Certificate valid for `planner.org-b.example`. Signature over the card body valid against the key in `signatures[].protected`. 2. The card body declared `\"...",
    "condition_of_validity": "Treat the card as **authoritative** for delegation routing only when all of the following hold: - The card was retrieved over a channel whose TLS (or mTLS) principal is identical to the principal that will terminate the task submission. Concretely: `origin(card_url) == origin(card.url)`, or the card carries an explicit, signed binding (e.g., a `url` under th...",
    "decision_boundary": "The boundary is not \"is the card signed\" but \"does the card's routing field survive an identity check at submission time.\" Operationalize it as a pre-delegation gate: - **Same-origin card and endpoint** → authoritative; proceed with standard handshake. - **Cross-origin endpoint with signed binding to the same principal** → authoritative *after* verifying the...",
    "operational_effect": "When the gate is applied, delegation latency increases by one attestation round-trip on first contact per (caller, callee, endpoint) tuple; subsequent tasks reuse the attested binding with a TTL bounded by the card's cache headers and the caller's DNS TTL — whichever is shorter, because a repointed `url` is the exact failure mode the gate exists to catch. Wh..."
  },
  "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": "71b8ea4066b6e1478b827bf65e1778771cab74a35dba315b8dba7bc63beef3fc",
    "verified_classes": [
      "AgentCardRoutingTrustError",
      "AttestedEndpoint"
    ],
    "verified_functions": [
      "_origin",
      "resolve_delegation_target",
      "submit_task"
    ],
    "verified_functions_count": 3,
    "defensive_guards_count": 4,
    "raised_exceptions": [
      "AgentCardRoutingTrustError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "hashlib",
      "urllib"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}