{
  "schema_version": "1.3.0",
  "slug": "which-invariants-prevent-stale-agent-card-capability-claims-from-being-treated-as-authorization-after-a-task-has-already-transitioned",
  "title": "Which invariants prevent stale Agent Card capability claims from being treated as authorization after a task has already transitioned",
  "date_of_record": "2026 November 14",
  "scope": "Applies to A2A v1.0 deployments where a client caches an Agent Card (`/.well-known/agent-card.json`) and later submits tasks or accepts push-notification callbacks against that cached card. Does not apply to stateless single-call invocations that re-fetch the card on every request, nor to deployments where the card is served with `Cache-Control: no-store`.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/which-invariants-prevent-stale-agent-card-capability-claims-from-being-treated-as-authorization-after-a-task-has-already-transitioned.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/which-invariants-prevent-stale-agent-card-capability-claims-from-being-treated-as-authorization-after-a-task-has-already-transitioned.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/which-invariants-prevent-stale-agent-card-capability-claims-from-being-treated-as-authorization-after-a-task-has-already-transitioned.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1281,
    "python_slice_tokens": 221,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "There is a persistent conflation between two different questions: *\"Is this skill advertised on the card?\"* and *\"Is this caller authorized to invoke this skill right now?\"* The Agent Card is a **capability advertisement**, not an authorization grant. The non-obvious boundary is that A2A task lifecycle transitions (`submitted → working → input-required → com...",
    "what_was_observed": "A client agent discovered a card advertising a `skills` entry with `inputModes: [\"text/plain\"]` and `outputModes: [\"application/json\"]`. It submitted a task, received `submitted`, then `working`, then `input-required` with a follow-up question. While the task sat in `input-required`, the operator rotated the skill's authorization policy (the skill was moved behind a scope gate) and republished the card. The client, h...",
    "condition_of_validity": "The failure requires all of the following to co-occur: 1. The client caches the Agent Card beyond a single request (any TTL > 0). 2. The task lifecycle has at least one **resumable edge** (`input-required → working`, `auth-required → working`) where the server accepts client-supplied continuation. 3. Authorization policy for a skill can change independently ...",
    "decision_boundary": "The correct decision at a resumable edge is: - **Reject** the continuation if the skill's *current* policy no longer authorizes the caller, regardless of what the card said at submission time. Return `failed` with a `status.message` indicating policy change, not a generic 403 that the client will retry. - **Accept** only when the live policy store authorizes...",
    "operational_effect": "When this invariant is violated, the observable symptoms are misleading: tasks complete successfully but against revoked capabilities (silent over-permission), and webhook deliveries drop silently after key rotation (apparent flakiness). Both erode the audit trail because the task record shows a clean `completed` transition with no marker that authorization ..."
  },
  "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": "d75043775e060f187e1493ab24842b6ad50e9831062c46587fe2b8cf3f907ca7",
    "verified_classes": [
      "StaleCardAuthorizationError",
      "WebhookSignatureKeyMismatch"
    ],
    "verified_functions": [
      "resume_task"
    ],
    "verified_functions_count": 1,
    "defensive_guards_count": 3,
    "raised_exceptions": [
      "StaleCardAuthorizationError",
      "WebhookSignatureKeyMismatch"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}