{
  "schema_version": "1.3.0",
  "slug": "what-happens-when-an-instance-advertises-an-agent-card-mid-rollout-and-the-task-state-machine-disagrees-with-the-webhook-binding",
  "title": "What happens when an instance advertises an Agent Card mid-rollout and the task state machine disagrees with the webhook binding",
  "date_of_record": "2026 November 12",
  "scope": "Applies to A2A v1.0 deployments where Agent Card discovery, task lifecycle transitions, and push-notification webhook callbacks are served by independently deployable components. Does not apply to single-process reference implementations where all three are co-located and share a single transaction boundary.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-advertises-an-agent-card-mid-rollout-and-the-task-state-machine-disagrees-with-the-webhook-binding.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-advertises-an-agent-card-mid-rollout-and-the-task-state-machine-disagrees-with-the-webhook-binding.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-advertises-an-agent-card-mid-rollout-and-the-task-state-machine-disagrees-with-the-webhook-binding.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1957,
    "python_slice_tokens": 313,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "An Agent Card is a *declarative* artifact: it asserts capabilities (`pushNotifications: true`, supported `taskStates`, `streaming`), a canonical `url`, and a `capabilities` block. A task lifecycle is a *stateful* artifact: it moves through `submitted → working → input-required → completed | failed | canceled`, and each transition is a fact that must be durab...",
    "what_was_observed": "A client resolved the Agent Card via `GET /.well-known/agent-card.json` against instance A. The Card advertised `capabilities.pushNotifications: true`, a `defaultInputModes`/`defaultOutputModes` pair, and a `skills` array. The client opened a task with `message/send`, received `state: submitted`, then called `tasks/pushNotificationConfig/set` with a callback URL. The registration returned `200 OK` with a config ID. I...",
    "condition_of_validity": "The boundary holds — that is, the Card is a safe contract — only when all three of the following are true simultaneously: 1. The Card endpoint is *not* marked healthy until the push-notification dispatcher has an established, verified subscription to the task event bus, and has rebuilt its subscription index from the authoritative store. 2. Task state transi...",
    "decision_boundary": "The correct operational decision is to **decouple Card publication from instance readiness by making the dispatcher a precondition of Card health, not a peer.** Concretely: - The readiness probe for `/.well-known/agent-card.json` must gate on dispatcher subscription health, not on process liveness. A Card served by a pod whose dispatcher is not subscribed is...",
    "operational_effect": "When the boundary is respected, the observable behavior is a brief period where the Card endpoint returns `503` during rollout, and clients retry discovery. This is correct and cheap: no task is opened against an instance that cannot honor it, no registration is accepted and dropped, and the state machine and webhook binding remain consistent with the advert..."
  },
  "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": "c6935e6d9a1c39c83453816ceb6714c167f5b2bec954a095d512125e6d4f552a",
    "verified_classes": [
      "AgentCardContractError"
    ],
    "verified_functions": [
      "publish_agent_card",
      "accept_push_registration"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 5,
    "raised_exceptions": [
      "AgentCardContractError"
    ],
    "sample_fail_closed_invariants": [
      "refusing to publish Card with pushNotifications=true: dispatcher not subscribed to task event bus",
      "refusing to publish Card: dispatcher registration index not rebuilt from authoritative store",
      "refusing to publish Card: declared taskStates not supported by current store schema",
      "refusing to publish Card with streaming=true: event fan-out not wired to task store"
    ],
    "stdlib_dependencies": [],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}