{
  "schema_version": "1.3.0",
  "slug": "when-must-a-bft-consensus-instance-reject-a-plan-commitment-it-has-already-quorum-certified",
  "title": "When must a BFT consensus instance reject a plan commitment it has already quorum-certified?",
  "date_of_record": "2026 November 6",
  "scope": "Applies to BFT consensus instances that certify *plan commitments* (a signed intent to execute a multi-step action sequence against shared state) rather than single-value writes, where the committed object carries a validity horizon, a dependency set on other agents' commitments, and an execution precondition. Does not apply to single-shot value agreement, nor to commitment schemes whose payloads are immutable and dependency-free at certification time.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/when-must-a-bft-consensus-instance-reject-a-plan-commitment-it-has-already-quorum-certified.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/when-must-a-bft-consensus-instance-reject-a-plan-commitment-it-has-already-quorum-certified.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/when-must-a-bft-consensus-instance-reject-a-plan-commitment-it-has-already-quorum-certified.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1210,
    "python_slice_tokens": 248,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The non-obvious boundary is between **certification validity** and **execution admissibility**. A quorum certificate proves that a supermajority of replicas agreed on the *bytes* of a commitment at a point in time. It does **not** prove that the commitment remains admissible at the moment an agent attempts to execute it. In multi-agent plan commitment, the o...",
    "what_was_observed": "An instance executed a plan commitment `P_a` carrying a QC from view `v`. Between certification and execution, a concurrent commitment `P_b` reached quorum in view `v+1`, asserting an exclusive lock on a shared resource that `P_a`'s step 3 precondition requires. `P_a`'s QC remained cryptographically valid — no replica equivocated, no view change was faulty. The executor nonetheless attempted `P_a` because it checked ...",
    "condition_of_validity": "A certified plan commitment is admissible for execution **only if**, at execution time, the executor re-validates: 1. The QC's view is not older than the latest committed view touching any member of the commitment's dependency set (stale-QC guard). 2. Every precondition predicate evaluates true against the *current* committed shared state, not the state snap...",
    "decision_boundary": "- **Re-validate (admit):** QC valid *and* dependency set unchanged since certification *and* all preconditions hold now. Execute. - **Re-propose (defer):** QC valid but a dependency changed. The commitment is still *true* (the quorum agreed) but no longer *actionable*. Re-enter consensus with an amended plan that either reorders around the new lock or abando...",
    "operational_effect": "Executors that skip re-validation exhibit *optimistic execution drift*: they run plans whose preconditions died between certification and execution, producing partial side effects that require compensation and, in adversarial settings, exploitable windows where a Byzantine agent times a conflicting commitment to land exactly in the certification-to-execution..."
  },
  "matched_failure_symptoms": [
    "SPLIT_BRAIN_OR_ZOMBIE_WORKER"
  ],
  "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": "63ebf4fb89d5abaa2dd3309b270981bfe444cf3e420dd253b914132d027f6a3e",
    "verified_classes": [
      "InadmissibleCommitment",
      "PlanCommitment",
      "SharedState"
    ],
    "verified_functions": [
      "admit_for_execution",
      "__init__"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 3,
    "raised_exceptions": [
      "InadmissibleCommitment"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}