{
  "schema_version": "1.3.0",
  "slug": "under-what-conditions-must-an-instance-refuse-to-merge-speculative-agent-branches-whose-partial-results-fail-byzantine-quorum-intersection",
  "title": "Under what conditions must an instance refuse to merge speculative agent branches whose partial results fail Byzantine quorum intersection",
  "date_of_record": "2026 November 11",
  "scope": "Applies to orchestrators that run parallel speculative agent branches (tree-of-thought, best-of-N, or multi-agent fan-out) and merge their partial results into a single committed state under an assumption of at most *f* Byzantine branches out of *n*. Does not apply to single-branch execution, to branches that share a trusted executor with no adversarial input channel, or to merges that are purely advisory and never promoted to committed state.",
  "projections": {
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    "method_python_slice_uri": "https://corpusfetch.com/c/under-what-conditions-must-an-instance-refuse-to-merge-speculative-agent-branches-whose-partial-results-fail-byzantine-quorum-intersection.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/under-what-conditions-must-an-instance-refuse-to-merge-speculative-agent-branches-whose-partial-results-fail-byzantine-quorum-intersection.warrant.json"
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  "remnant_summary": {
    "core_distinction": "The common failure model treats branch merging as a *consensus* problem: collect partial results, run a quorum rule, commit the majority. The non-obvious failure is that speculative branches do **not** produce votes over a fixed value set — they produce *partially ordered, non-comparable artifacts* (partial plans, partial tool-call traces, partial KV-derived...",
    "what_was_observed": "In a fan-out of *n* = 7 speculative branches with tolerance *f* = 2, an adversarial branch emitted a partial tool-call trace that was a valid prefix of two different honest traces. The merger, operating on longest-common-prefix semantics, accepted the adversarial prefix as the merge base for both honest branches. The resulting committed trace contained a tool invocation (a write to a shared scratch resource) that app...",
    "condition_of_validity": "A merge may be committed only if all of the following hold; if any fails, the instance must refuse and escalate rather than commit: 1. **Merge-closure quorum.** The set of partials consumed by the merge operation — including any partial used only as a merge base or prefix anchor — must contain at least *n − f* distinct honest-attested branches. Attestation m...",
    "decision_boundary": "The boundary between \"merge and commit\" and \"refuse and escalate\" is drawn at the first field in the merged artifact whose provenance set is not a subset of the honest-attested consumed set. Concretely: - If merge-closure quorum holds **and** every committed field's provenance is honest-only **and** the merge is idempotent and order-independent → commit. - I...",
    "operational_effect": "Enforcing this boundary converts a class of silent semantic corruption into an explicit, auditable refusal. In the observed fan-out, the poisoned merge was caught at the cross-field invariant check and escalated; the re-fan-out with prefix-anchor exclusion produced an honest-only committed trace on the first retry. The cost is additional attestation traffic ..."
  },
  "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": "ec9c53d2a77ed5491d91aee1fe51a6adcbf80f89cae4899e305822f563228a9f",
    "verified_classes": [
      "MergePoisonedError",
      "MergeQuorumError",
      "Partial",
      "MergeResult"
    ],
    "verified_functions": [
      "assert_merge_safe",
      "commit_merge"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 3,
    "raised_exceptions": [
      "MergePoisonedError",
      "MergeQuorumError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}