{
  "schema_version": "1.3.0",
  "slug": "what-structural-signals-indicate-a-quorum-intersection-failure-in-multi-agent-task-commitment-before-byzantine-agreement-stalls",
  "title": "What structural signals indicate a quorum-intersection failure in multi-agent task commitment before Byzantine agreement stalls",
  "date_of_record": "2026 November 13",
  "scope": "Applies to BFT task-commitment protocols where N agents (N ≥ 3f+1) commit work items via signed proposals and a quorum of 2f+1 acknowledgements, and where agents may equivocate or selectively withhold. Does not apply to crash-fault-only systems, leaderless CRDT-style merges, or settings where task commitment is delegated to a single trusted coordinator with non-repudiable logging.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/what-structural-signals-indicate-a-quorum-intersection-failure-in-multi-agent-task-commitment-before-byzantine-agreement-stalls.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/what-structural-signals-indicate-a-quorum-intersection-failure-in-multi-agent-task-commitment-before-byzantine-agreement-stalls.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/what-structural-signals-indicate-a-quorum-intersection-failure-in-multi-agent-task-commitment-before-byzantine-agreement-stalls.warrant.json"
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  "remnant_summary": {
    "core_distinction": "The non-obvious boundary is between **quorum-count failure** and **quorum-intersection failure**. Quorum-count failure is visible: fewer than 2f+1 acks arrive, timeouts fire, retries occur. Quorum-intersection failure is invisible at the count level: every agent observes a locally valid quorum, every signature verifies, and yet two disjoint sets of 2f+1 agen...",
    "what_was_observed": "In a 7-agent commitment mesh (f=2, quorum=5) assigning tasks to a shared work queue, a single Byzantine agent (A3) equivocated on proposal digest `d1`: it sent `ack(d1)` to the leader partition and `ack(d1')` to a lagging partition during a 400 ms network partition. Both partitions independently assembled 5-ack quorums. The intersection was {A3, A5, A6} — size 3 ≥ f+1, so the intersection *existed*, but A3's contribu...",
    "condition_of_validity": "This diagnosis is valid only when: (a) signatures are non-repudiable and bound to the proposal digest, so a double-sign is provable; (b) the protocol requires quorum intersection of at least f+1 *honest* members, not merely f+1 members; (c) gossip between partitions eventually merges, allowing post-hoc reconstruction of the vote graph. It is **invalid** when...",
    "decision_boundary": "The operational rule: **treat per-signer digest-set cardinality > 1 within an epoch as a hard stop, regardless of tally.** Do not wait for the tally to drop, do not wait for a timeout, and do not attempt to \"resolve\" by majority — a double-signed digest means the intersection invariant is already suspect and any quorum built on it is untrustworthy. Escalate ...",
    "operational_effect": "Applying this boundary converts a silent safety violation into a detectable liveness event. In the observed incident, the digest-cardinality check would have flagged A3 at +12 ms, before either partition finalized its quorum, allowing the commitment to be aborted cleanly rather than forked. The cost is a modest increase in false-positive view-changes during ..."
  },
  "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": "f93d8e3a9f5d20f9cccffcf9c91fba8e082a0377e15d3fb3bcd0d03bfd245bbd",
    "verified_classes": [
      "QuorumIntersectionError"
    ],
    "verified_functions": [
      "check_commitment_safety",
      "finalize_task"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 2,
    "raised_exceptions": [
      "QuorumIntersectionError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}