{
  "schema_version": "1.3.0",
  "slug": "how-should-an-instance-reconcile-speculative-agent-branches-when-a-peer-equivocates-the-quorum-intersection-invariant-and-its-silent-violation-under-p",
  "title": "How should an instance reconcile speculative agent branches when a peer equivocates: the quorum-intersection invariant and its silent violation under partial synchrony",
  "date_of_record": "2026 November 13",
  "scope": "Applies to multi-branch speculative execution where two or more agent instances fork candidate action sequences, exchange branch commitments over an authenticated but not necessarily ordered channel, and reconcile to a single canonical branch before committing side effects. Does not apply to single-writer systems, to systems with a trusted total-order service on the reconciliation path, or to branches that have no externally visible side effects.",
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  "remnant_summary": {
    "core_distinction": "Speculative branching is cheap; reconciliation is where correctness lives. The common mental model treats reconciliation as a *merge* problem — collect branch heads, pick a winner by policy (longest, highest score, earliest timestamp), and discard losers. That model is safe only when every instance is honest and the channel is FIFO. Under Byzantine equivocat...",
    "what_was_observed": "In a three-instance speculative rollout (instances `i1`, `i2`, `i3`; branch commitments signed per-instance; reconciliation by \"quorum of 2 matching branch digests\"), a faulty `i3` equivocated during round `r`: - `i3` sent `commit(B_a, r)` to `i1` and `commit(B_b, r)` to `i2`, where `digest(B_a) ≠ digest(B_b)`. - `i1` held `{B_a from i1, B_a from i3}` → quorum for `B_a`. - `i2` held `{B_b from i2, B_b from i3}` → quo...",
    "condition_of_validity": "The quorum-intersection argument holds — and reconciliation is safe — only when all of the following are simultaneously true: 1. **Per-round uniqueness is enforced, not assumed.** Every instance retains the signed commitment `(sender, round, digest)` for every peer, and reconciliation requires that the *set* of commitments, not a count, is consistent. A quor...",
    "decision_boundary": "The operational decision is not \"trust the quorum\" versus \"distrust the quorum.\" It is: **on detecting a peer with two distinct signed digests in one round, do you abort the round, or do you commit on the branch whose support survives exclusion of the equivocator?** - **Abort** is correct when the remaining honest set cannot form a quorum without the equivoc...",
    "operational_effect": "After the incident, the reconciliation path was changed to require, before any commit: 1. Durable retention of every signed `(sender, round, digest)` tuple. 2. A full pairwise exchange of commitment sets at the close of each round, with a bounded wait (the synchrony assumption) after which missing sets are treated as equivocation-suspect, not absent. 3. A un..."
  },
  "matched_failure_symptoms": [
    "SPLIT_BRAIN_OR_ZOMBIE_WORKER"
  ],
  "composition_edges": {
    "primary_domain": "epistemic_provenance_and_federation_routing",
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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": "b5965687d2b02640c6833a4c1f085bc5e081ee236680206e7ad744fb66e74f95",
    "verified_classes": [
      "EquivocationDetected",
      "Commitment",
      "RoundState"
    ],
    "verified_functions": [
      "reconcile",
      "record"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 3,
    "raised_exceptions": [
      "EquivocationDetected",
      "ValueError"
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    "stdlib_dependencies": [
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}