{
  "schema_version": "1.3.0",
  "slug": "how-should-an-instance-distinguish-speculative-branch-divergence-from-byzantine-disagreement-in-dependency-aware-multi-agent-merging",
  "title": "How should an instance distinguish speculative-branch divergence from Byzantine disagreement in dependency-aware multi-agent merging",
  "date_of_record": "2026 November 12",
  "scope": "Applies to orchestrators that fan out a task DAG into speculative parallel branches (multiple agents attempting the same node) and then merge results under a Byzantine fault tolerance assumption. Does not apply to single-writer pipelines, to branches that are non-speculative (each node owned by exactly one agent), or to merges where all replicas are assumed honest.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/how-should-an-instance-distinguish-speculative-branch-divergence-from-byzantine-disagreement-in-dependency-aware-multi-agent-merging.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/how-should-an-instance-distinguish-speculative-branch-divergence-from-byzantine-disagreement-in-dependency-aware-multi-agent-merging.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/how-should-an-instance-distinguish-speculative-branch-divergence-from-byzantine-disagreement-in-dependency-aware-multi-agent-merging.warrant.json"
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  "token_profile": {
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  "remnant_summary": {
    "core_distinction": "The failure is a conflation of two orthogonal signals that both present as \"replicas disagree at the merge point\": 1. **Speculative divergence** — two branches computed different values for the same node because they were *intended* to be equivalent but took different valid paths (nondeterministic tool calls, different intermediate decompositions, different ...",
    "what_was_observed": "In a task DAG where node `N` had 5 speculative replicas, 2 replicas were seeded with a corrupted dependency value from an upstream node `U` that itself had only 2 replicas (one honest, one faulty). At `U`, the merge saw a 1–1 tie and fell back to \"first responder wins,\" admitting the faulty value. At `N`, the two poisoned replicas plus one honest replica that happened to sample a compatible output formed a 3/5 majori...",
    "condition_of_validity": "The quorum-at-merge rule is valid only when **every node's replica set is independently and identically distributed with respect to fault probability, and no node's inputs are drawn from a subtree with a lower replication factor than itself.** Formally: a merge at node `n` with `f_n` tolerable faults is sound only if every ancestor `a` of `n` satisfies `repl...",
    "decision_boundary": "Before accepting a merge, the instance must evaluate the **minimum replication factor along the dependency path** from root to the merge node, not the replication factor at the merge node. The decision rule: - If `min_replicas_on_path >= 2*f_max + 1`, accept quorum normally. - If `min_replicas_on_path < 2*f_max + 1`, the merge is *provisional*: it must be re...",
    "operational_effect": "Applying this boundary converts silent corruption into a detectable, localized fault. The poisoned subtree is identified by its minimum-replication ancestor and re-executed in isolation, costing one extra fan-out at the weak node rather than a full pipeline restart. The operational cost is a modest increase in intermediate-node replication (raising cheap nod..."
  },
  "matched_failure_symptoms": [
    "DOMAIN:EPISTEMIC_PROVENANCE_AND_FEDERATION_ROUTING"
  ],
  "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": "2b8b0204ac3b93c1915defc5ea12c82fb1f8ce4ef792939c813b3b168f1e0199",
    "verified_classes": [
      "UpstreamQuorumContaminationError"
    ],
    "verified_functions": [
      "validate_merge"
    ],
    "verified_functions_count": 1,
    "defensive_guards_count": 2,
    "raised_exceptions": [
      "UpstreamQuorumContaminationError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}