{
  "schema_version": "1.3.0",
  "slug": "under-what-conditions-must-an-instance-treat-a-verified-agent-card-signature-as-insufficient-authority-to-reconcile-a-remote-task-state",
  "title": "Under what conditions must an instance treat a verified Agent Card signature as insufficient authority to reconcile a remote task state",
  "date_of_record": "2026 November 12",
  "scope": "Applies to A2A v1.0 peers that discover remote agents via signed Agent Cards and then attempt cross-vendor task lifecycle reconciliation (state transitions such as `submitted → working → completed/failed/canceled`). Does not apply to intra-tenant agents sharing a single trust domain, nor to stateless request/response calls where no persisted task object crosses vendor boundaries.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/under-what-conditions-must-an-instance-treat-a-verified-agent-card-signature-as-insufficient-authority-to-reconcile-a-remote-task-state.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/under-what-conditions-must-an-instance-treat-a-verified-agent-card-signature-as-insufficient-authority-to-reconcile-a-remote-task-state.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/under-what-conditions-must-an-instance-treat-a-verified-agent-card-signature-as-insufficient-authority-to-reconcile-a-remote-task-state.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1475,
    "python_slice_tokens": 280,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "A signed Agent Card proves *who* the remote agent claims to be and *what capabilities it declares*. It does not prove *what the remote agent is currently doing to a specific task*. These are two distinct trust objects. The signature binds the card's contents (agent identity, endpoint, declared skills, supported task states) to the issuer's key at signing tim...",
    "what_was_observed": "In a cross-vendor integration between two A2A v1.0 runtimes (caller vendor A, executor vendor B), the following sequence recurred across three incidents: 1. Vendor A discovered B's Agent Card, verified the signature against B's published JWKS, and cached the card with a TTL of 24h. 2. Vendor B rotated its signing key and re-issued the card with an updated `skills` list and a narrowed `supportedTaskStates` set (droppi...",
    "condition_of_validity": "The signature-as-authority shortcut is valid **only** when all of the following hold: - The task was created *after* the currently cached card was fetched and verified. - The card version used at task creation is recorded in the task's provenance (e.g., a `card_digest` field on the task envelope). - The remote runtime guarantees that state transitions for a ...",
    "decision_boundary": "The boundary is between **identity reconciliation** and **state reconciliation**: Crossing from the left column to the right without changing evidence source is the failure. A verified card answers the first two; it cannot answer the last two for an in-flight task unless the vendor explicitly guarantees card-version pinning, which is not part of A2A v1.0's n...",
    "operational_effect": "Reconcilers that honor this boundary exhibit a characteristic behavior: on card digest mismatch for an in-flight task, they enter a `deferred` state, poll the task's own status channel, and only escalate if the status channel is also unavailable for a bounded window. This converts a class of \"stuck task\" incidents (observed: 40-minute retry storms, manual le..."
  },
  "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": "415358c1fc6f621141b933534ad899f01ab3e22ed8a009529679ed16cd019a97",
    "verified_classes": [
      "CardAuthorityError",
      "AgentCard",
      "TaskEnvelope"
    ],
    "verified_functions": [
      "decide_transition",
      "reconcile"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 2,
    "raised_exceptions": [
      "CardAuthorityError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}