{
  "schema_version": "1.3.0",
  "slug": "which-invariants-prevent-silent-task-resurrection-across-a2a-v1-0-agent-card-re-resolution",
  "title": "Which invariants prevent silent task resurrection across A2A v1.0 Agent Card re-resolution",
  "date_of_record": "2026 November 12",
  "scope": "Applies to A2A v1.0 clients that cache Agent Cards and re-resolve them mid-task, where `Task.status.state` transitions are driven by a remote agent whose card `capabilities` or `endpoint` may change between resolutions. Does not apply to stateless request/response skills that carry no `Task` object, nor to in-process agents sharing a single card snapshot.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/which-invariants-prevent-silent-task-resurrection-across-a2a-v1-0-agent-card-re-resolution.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/which-invariants-prevent-silent-task-resurrection-across-a2a-v1-0-agent-card-re-resolution.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/which-invariants-prevent-silent-task-resurrection-across-a2a-v1-0-agent-card-re-resolution.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1499,
    "python_slice_tokens": 225,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The non-obvious boundary is not \"stale card\" versus \"fresh card.\" It is the distinction between **card identity continuity** and **task identity continuity**. A2A v1.0 makes the Agent Card the discovery unit and the `Task` the lifecycle unit, but it specifies no binding that ties a given `Task.id` to the card revision under which it was created. When a clien...",
    "what_was_observed": "A client issued `tasks/send` against agent `A`, receiving `Task.id = t-7f3a` in state `working`, with `capabilities.streaming = true`. Mid-stream, the SSE connection dropped. Per its retry policy the client re-resolved `/.well-known/agent.json`. The new card advertised the *same* `name` and `url` but `capabilities.streaming = false` and a reduced `skills` array; the operator had redeployed `A` behind a new revision t...",
    "condition_of_validity": "The silent-resurrection failure requires the conjunction of three conditions, and is excluded if any is absent: 1. **Task-id reuse across revisions.** The remote agent's id space is not monotonic across card revisions — either through deterministic seeding, a restored snapshot, or a namespace collision after a redeploy. 2. **Card revision change without a ta...",
    "decision_boundary": "The operational decision is whether to *trust a re-resolved card as continuous with the prior one for the purpose of continuing an existing task*. The correct boundary: - If the re-resolved card's `url`, `capabilities`, and the `skills[].id` set are **byte-identical** to the cached card, continuation is safe; the task id remains a valid handle. - If **any** ...",
    "operational_effect": "The practical consequence is that **card caching must be revision-scoped, not merely TTL-scoped**, and task handles must be bound to the card revision under which they were minted. Concretely: store a hash of the resolved card alongside every `Task.id` you track; on every re-resolution, recompute the hash and refuse to continue any task whose stored hash no ..."
  },
  "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": "30b2c7737a0f1423a22a6dd34b4d0daa41c1b9a3c115199177935661b5d4f7ba",
    "verified_classes": [
      "TaskResurrectionError",
      "CardSnapshot",
      "TaskHandle"
    ],
    "verified_functions": [
      "continue_task",
      "revision_hash"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 2,
    "raised_exceptions": [
      "TaskResurrectionError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "hashlib",
      "json",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}