{
  "schema_version": "1.3.0",
  "slug": "under-what-conditions-must-an-instance-reject-an-a2a-v1-0-agent-card-whose-capabilities-pushnotifications-flag-is-true-but-whose-webhook-binding-canno",
  "title": "Under what conditions must an instance reject an A2A v1.0 agent card whose `capabilities.pushNotifications` flag is true but whose webhook binding cannot be authenticated at task-negotiation time",
  "date_of_record": "2026 November 9",
  "scope": "Applies to A2A v1.0 client and orchestrator instances that discover remote agents via agent card fetch, negotiate `tasks/send` or `tasks/sendSubscribe` lifecycles, and register push-notification webhooks. Does not apply to pure request/response A2A interactions with `pushNotifications: false`, nor to A2A v0.2 legacy cards lacking the `capabilities` object.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/under-what-conditions-must-an-instance-reject-an-a2a-v1-0-agent-card-whose-capabilities-pushnotifications-flag-is-true-but-whose-webhook-binding-canno.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/under-what-conditions-must-an-instance-reject-an-a2a-v1-0-agent-card-whose-capabilities-pushnotifications-flag-is-true-but-whose-webhook-binding-canno.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/under-what-conditions-must-an-instance-reject-an-a2a-v1-0-agent-card-whose-capabilities-pushnotifications-flag-is-true-but-whose-webhook-binding-canno.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1476,
    "python_slice_tokens": 247,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "A2A v1.0 separates *capability advertisement* from *binding verification*. The agent card is a self-asserted document: `capabilities.pushNotifications: true` means the remote agent claims it will POST task-state updates to a client-supplied `PushNotificationConfig.url`. It does **not** mean the client has proven it can receive those POSTs, nor that the remot...",
    "what_was_observed": "Across a set of orchestrator-to-worker integrations, the following sequence recurred: 1. Client fetches agent card. Card declares `capabilities.pushNotifications: true`, `defaultInputModes`/`defaultOutputModes`, and a `skills` array. No field describes the remote's *ingress* authentication expectations for webhook POSTs — that is negotiated per-task via `PushNotificationConfig.authentication`. 2. Client calls `tasks/...",
    "condition_of_validity": "The \"accept the card and proceed\" path is valid **only** when all of the following hold: - The client has a verified, externally reachable webhook endpoint whose accepted authentication scheme is documented in the `PushNotificationConfig.authentication` it sends, **and** the client has confirmed (via a pre-flight probe or prior successful delivery) that the ...",
    "decision_boundary": "The decision is not \"is `pushNotifications` true?\" but \"**has the binding been acknowledged?**\" A2A v1.0 provides no explicit webhook-handshake message; the closest available signal is a successful `tasks/pushNotificationConfig/set` response combined with the remote echoing back the config it will use. If the remote's echo differs from the config sent (e.g.,...",
    "operational_effect": "Implementing the boundary changes three things: (1) the client's task state machine gains an explicit `push_unverified` flag that forces polling; (2) the orchestrator's \"stuck task\" alert fires on `working` tasks older than the reconciliation interval rather than never; (3) the remote's silent 401s become visible because the client's polling detects the `com..."
  },
  "matched_failure_symptoms": [
    "DUPLICATE_MUTATION_OR_BILLING"
  ],
  "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": "64d295a2e83c7b1c05b3376c7ac46196d83500639e692de2e06e9aa57ab4ca74",
    "verified_classes": [
      "PushBindingUnverifiedError",
      "AgentCard",
      "PushNotificationConfig",
      "PushConfigAck"
    ],
    "verified_functions": [
      "negotiate_push_binding"
    ],
    "verified_functions_count": 1,
    "defensive_guards_count": 2,
    "raised_exceptions": [
      "PushBindingUnverifiedError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}