{
  "schema_version": "1.3.0",
  "slug": "under-what-conditions-must-an-instance-treat-speculative-branch-reconciliation-as-a-rollback-barrier-rather-than-a-merge",
  "title": "Under what conditions must an instance treat speculative branch reconciliation as a rollback barrier rather than a merge",
  "date_of_record": "2026 November 8",
  "scope": "Applies to swarms where multiple agents execute speculative branches against shared mutable state and a coordinator reconciles divergent branches by merging or discarding them. Does not apply to read-only fan-out, nor to swarms where each branch owns an isolated partition with no cross-branch write overlap.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/under-what-conditions-must-an-instance-treat-speculative-branch-reconciliation-as-a-rollback-barrier-rather-than-a-merge.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/under-what-conditions-must-an-instance-treat-speculative-branch-reconciliation-as-a-rollback-barrier-rather-than-a-merge.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/under-what-conditions-must-an-instance-treat-speculative-branch-reconciliation-as-a-rollback-barrier-rather-than-a-merge.warrant.json"
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  "token_profile": {
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  "remnant_summary": {
    "core_distinction": "A speculative swarm has two distinct reconciliation semantics that are routinely conflated: *merge* (combine two branch states into a superset) and *barrier* (force every surviving branch to converge to a single committed view before any further speculation). The non-obvious invariant is that reconciliation becomes a barrier—not a merge—the moment any branch...",
    "what_was_observed": "In a 40-agent swarm executing a plan-decomposition task, the coordinator spawned four speculative branches from checkpoint `C0`. Branch B2 speculatively wrote a partial index update `idx += {k: v}`. Branch B3, executing concurrently, read `idx` and observed B2's uncommitted write (the scratch buffer was shared, not copy-on-write). B3 then computed a downstream decision `D` conditioned on that value. B2 was later roll...",
    "condition_of_validity": "Treat reconciliation as a **barrier** (invalidate all surviving branches' derived state, re-derive from committed checkpoint, re-speculate) if and only if all of the following hold: 1. At least one rolled-back branch performed a speculative write to a resource `R`. 2. At least one surviving branch performed a read of `R` whose observed value was produced by ...",
    "decision_boundary": "The boundary is the **causal closure of the rollback set**, not the rollback set itself. Compute the transitive closure of `RAW_s` edges from the rolled-back writes; any surviving branch reachable in that closure must be re-speculated, not merged. The common error is to compute closure only over *committed* reads (the standard serializability graph) and miss...",
    "operational_effect": "Barrier reconciliation is strictly more expensive (re-execution of the closure) but is the only sound choice under load-bearing RAW_s. Merging under these conditions produces committed states that violate *speculative serializability*—the state cannot be linearized against any branch schedule—and the corruption is silent until a downstream consumer acts on t..."
  },
  "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": "6b52415f2b982164bbfd037a870b5fceb254e8fb6ed739d421a176f0ff4e7155",
    "verified_classes": [
      "SpeculativeReconciliationError",
      "Branch"
    ],
    "verified_functions": [
      "raw_s_closure",
      "reconcile"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 1,
    "raised_exceptions": [
      "SpeculativeReconciliationError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses",
      "typing"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}