{
  "schema_version": "1.3.0",
  "slug": "what-happens-when-an-instance-advertises-an-agent-card-whose-pushnotifications-capability-is-true-but-whose-webhook-receiver-cannot-complete-the-a2a-h",
  "title": "What happens when an instance advertises an Agent Card whose `pushNotifications` capability is true but whose webhook receiver cannot complete the A2A handshake before the first task transition",
  "date_of_record": "2026 November 12",
  "scope": "Applies to A2A v1.0 peer discovery where an Agent Card is fetched from `/.well-known/agent.json` (or the registry equivalent) and the remote agent declares `capabilities.pushNotifications: true`. Does not apply to pull-only (`tasks/get` polling) clients, nor to v0.x drafts where the push config was embedded in the task creation payload rather than bound at registration time.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-advertises-an-agent-card-whose-pushnotifications-capability-is-true-but-whose-webhook-receiver-cannot-complete-the-a2a-h.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-advertises-an-agent-card-whose-pushnotifications-capability-is-true-but-whose-webhook-receiver-cannot-complete-the-a2a-h.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-advertises-an-agent-card-whose-pushnotifications-capability-is-true-but-whose-webhook-receiver-cannot-complete-the-a2a-h.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1822,
    "python_slice_tokens": 375,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "There are two independent truths an Agent Card can express, and they are routinely conflated: 1. **Capability truth** — the remote agent *can* emit push notifications for state transitions it owns. 2. **Binding truth** — a specific webhook URL registered by *this* client has been acknowledged and is reachable *from the remote agent's egress path*. The Agent ...",
    "what_was_observed": "A coordinating agent (Client) discovered a Worker agent via a registry. The Worker's Agent Card declared: Client called `tasks/send` with a `pushNotificationConfig` containing `{ url, token }`. The Worker returned a `Task` in state `submitted` with a `pushNotificationConfig` echoed back — **but without a `validationToken` field and without an `id`**. Per A2A v1.0, the echoed config's presence is *not* proof of bindin...",
    "condition_of_validity": "This analysis holds when **all** of the following are true: - The remote declares `pushNotifications: true` and the client relies on push (not polling) for terminal-state detection. - The client terminalizes tasks on webhook timeout without a confirming `tasks/get`. - The remote enforces the v1.0 rule that unvalidated webhook configs receive no deliveries (c...",
    "decision_boundary": "The operational rule: **treat `pushNotifications: true` as a precondition for attempting binding, never as evidence of binding.** A task may only enter a state machine that depends on push delivery after the client has observed one of: - a `pushNotificationConfig/get` response containing a server-assigned `id`, or - an inbound validation callback whose `vali...",
    "operational_effect": "After applying the rule, the Client's state machine gained a `binding_pending` state with an independent, longer timeout and a `tasks/get` fallback. In replay against the same Worker, the duplicate-execution rate for tasks whose binding exceeded the webhook timeout dropped from measurable to zero, and the Client/Worker terminal-state divergence rate went to ..."
  },
  "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": "67f2141e496143c0b4084f0c1ae43e006a3f9291035176b11ae2518890ca7d8d",
    "verified_classes": [
      "BindingNotConfirmedError",
      "TaskState",
      "PushBinding",
      "Task"
    ],
    "verified_functions": [
      "advance_on_webhook_timeout",
      "confirm_binding"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 5,
    "raised_exceptions": [
      "BindingNotConfirmedError"
    ],
    "sample_fail_closed_invariants": [
      "assert task.binding is not None"
    ],
    "stdlib_dependencies": [
      "dataclasses",
      "enum",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}