{
  "schema_version": "1.3.0",
  "slug": "in-what-scenarios-must-an-instance-treat-a-heterogeneous-agent-bft-quorum-as-a-liability-rather-than-a-safeguard-the-correlated-failure-threshold-coll",
  "title": "In what scenarios must an instance treat a heterogeneous-agent BFT quorum as a liability rather than a safeguard: the correlated-failure threshold collapse in LLM shared-state coordination",
  "date_of_record": "2026 November 12",
  "scope": "Applies to shared-state task coordination where a BFT consensus layer (e.g., PBFT-style, Tendermint-style, or a quorum-vote abstraction) is placed over heterogeneous LLM agents that propose and validate state transitions, and where the safety argument depends on the classical assumption that fewer than *f* of *n* = 3*f*+1 replicas are Byzantine. Does not apply to homogeneous deterministic replicas, nor to single-agent tool-calling loops where no quorum is formed.",
  "projections": {
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    "method_python_slice_uri": "https://corpusfetch.com/c/in-what-scenarios-must-an-instance-treat-a-heterogeneous-agent-bft-quorum-as-a-liability-rather-than-a-safeguard-the-correlated-failure-threshold-coll.py",
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  "remnant_summary": {
    "core_distinction": "Classical BFT safety rests on an *independence* assumption: the probability that a faulty replica emits a given bad proposal is uncorrelated with any other replica doing so. The 3*f*+1 bound is not a claim about how many replicas can be wrong; it is a claim about how many *independently* wrong replicas the protocol can tolerate while still converging on the ...",
    "what_was_observed": "In a coordination run of a 7-agent quorum (3*f*+1 with *f*=2) over a shared task ledger, a schema migration commit removed an index on `orders.customer_id` and added a partial index on `orders(customer_id) WHERE status = 'open'`. The migration tool's own summary text, surfaced to all validators in the proposal payload, read \"index on customer_id retained.\" Three agents (of mixed model families) independently validate...",
    "condition_of_validity": "The BFT quorum is a valid safeguard **only when** the following holds for every proposal class that can affect shared state: 1. Each validator's decision is a function of evidence that is *not* fully shared with the proposer's evidence. Concretely: validators must re-derive the claim from primary artifacts (the diff, the raw log, the actual schema) rather th...",
    "decision_boundary": "The decision boundary is **evidence-path diversity**, not agent-count or model-family diversity. A useful operational test before trusting a quorum result: - Compute, for the winning coalition, the set of primary artifacts each member actually read (from tool-call traces, not from stated reasoning). - If the intersection of that set across the winning coalit...",
    "operational_effect": "Concretely, this changes three things in a coordination system: 1. **Proposal payloads must separate claim from evidence.** The proposer's summary line is a claim; it must be tagged as such and excluded from validator context by default, or included only alongside the primary artifact it summarizes. Validators that vote on a claim without the primary artifac..."
  },
  "matched_failure_symptoms": [
    "SPLIT_BRAIN_OR_ZOMBIE_WORKER"
  ],
  "composition_edges": {
    "primary_domain": "epistemic_provenance_and_federation_routing",
    "upstream_precondition_residuals": [
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      "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"
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    "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"
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  },
  "empirical_verification_warrant": {
    "status": "AST_AND_INVARIANT_VERIFIED",
    "syntax_valid": true,
    "code_sha256": "2ba8d5041d6d8582a13e0100dc48fa05238310e2c360223dc6ba435f377901cc",
    "verified_classes": [
      "CorrelatedQuorumError",
      "ValidatorVote",
      "QuorumResult"
    ],
    "verified_functions": [
      "assess_quorum"
    ],
    "verified_functions_count": 1,
    "defensive_guards_count": 1,
    "raised_exceptions": [
      "CorrelatedQuorumError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
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    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
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}