{
  "schema_version": "1.3.0",
  "slug": "when-must-an-instance-refuse-to-reconcile-a-speculative-branch-the-rollback-watermark-invariant-in-multi-agent-speculative-execution",
  "title": "When must an instance refuse to reconcile a speculative branch: The rollback watermark invariant in multi-agent speculative execution",
  "date_of_record": "2026 November 13",
  "scope": "Applies to systems that run speculative agent branches against shared mutable state and reconcile them via rollback to a common fork point. Does not apply to branches that are fully isolated (copy-on-write snapshots with no shared live side effects) or to single-agent speculative decoding where the only shared resource is token budget.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/when-must-an-instance-refuse-to-reconcile-a-speculative-branch-the-rollback-watermark-invariant-in-multi-agent-speculative-execution.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/when-must-an-instance-refuse-to-reconcile-a-speculative-branch-the-rollback-watermark-invariant-in-multi-agent-speculative-execution.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/when-must-an-instance-refuse-to-reconcile-a-speculative-branch-the-rollback-watermark-invariant-in-multi-agent-speculative-execution.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1405,
    "python_slice_tokens": 274,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The non-obvious boundary is between *reconcilable* and *unreconcilable* speculative branches. A branch is reconcilable when its side effects are fully captured by the rollback log up to the fork point: every mutation it performed is invertible, and no external observer acted on its intermediate state. It becomes unreconcilable the moment an irreversible side...",
    "what_was_observed": "In a three-agent speculative pipeline (planner, executor, verifier), the executor branch issued a `charge` RPC at effect index 41 and then failed verification at index 58. The reconciler, keyed on the branch's *logical* status, saw the verifier rejection and initiated rollback to fork index 12. The rollback log replayed inverse operations for indices 12–58, including a compensating refund for the charge. The refund w...",
    "condition_of_validity": "The rollback watermark invariant holds only under these conditions: 1. Every external effect is assigned a monotonically increasing effect index at the moment it becomes observable outside the branch's isolation boundary — not at the moment it is *initiated*. 2. The watermark is the maximum effect index for which a verified inverse or idempotent compensation...",
    "decision_boundary": "When a speculative branch fails and reconciliation is requested, the correct decision is a function of the watermark, not of the branch's logical outcome: - `watermark >= max_effect_index` → reconcile normally (rollback or merge). - `watermark < max_effect_index` and all intervening effects are idempotent → reconcile with compensation, then re-verify the wat...",
    "operational_effect": "Enforcing the invariant converts a class of silent, delayed failures into immediate, attributable refusals. In the observed pipeline, adding the watermark check moved the fraud-alert incident from a 40-second-latency mystery to a synchronous refusal at reconciliation time, with the branch quarantined and the offending effect index named in the error. The cos..."
  },
  "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": "62fbafcb4b04bef985e9f043188d5075ba79feed02d26a0ea9c96cdf119e7601",
    "verified_classes": [
      "UnreconcilableBranchError",
      "Branch"
    ],
    "verified_functions": [
      "reconcile",
      "__init__"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 2,
    "raised_exceptions": [
      "UnreconcilableBranchError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "dataclasses"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}