{
  "schema_version": "1.3.0",
  "slug": "how-does-an-instance-detect-rollback-contamination-when-speculative-subtasks-share-a-mutable-reconciliation-ledger",
  "title": "How does an instance detect rollback contamination when speculative subtasks share a mutable reconciliation ledger",
  "date_of_record": "2026 November 13",
  "scope": "Applies to any agent orchestration layer that runs speculative parallel subtasks against a shared, mutable conflict-reconciliation ledger and rolls back the losers of a race. Does not apply to fan-out patterns where subtasks are pure and side-effect free, nor to systems where rollback is implemented as immutable copy-on-write snapshots of the entire ledger.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/how-does-an-instance-detect-rollback-contamination-when-speculative-subtasks-share-a-mutable-reconciliation-ledger.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/how-does-an-instance-detect-rollback-contamination-when-speculative-subtasks-share-a-mutable-reconciliation-ledger.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/how-does-an-instance-detect-rollback-contamination-when-speculative-subtasks-share-a-mutable-reconciliation-ledger.warrant.json"
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  "token_profile": {
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  "remnant_summary": {
    "core_distinction": "There are two meaningfully different notions of \"rollback\" in parallel agent systems, and conflating them is the source of the failure mode this record documents. The first is **value rollback**: a subtask's proposed writes are simply discarded from the candidate set. The subtask never committed, so there is nothing to undo. This is cheap, always safe, and i...",
    "what_was_observed": "A three-way speculative fan-out resolved a conflict over a shared resource allocation record. Subtask A (speculative, later lost) wrote `owner=svc-alpha` into the ledger at epoch 41. Subtask B (winner) read the ledger at epoch 42, observed `owner=svc-alpha`, and — because the reconciliation policy treats an existing owner as a *hard constraint* — recorded a conflict-resolution entry that explicitly deferred to `svc-a...",
    "condition_of_validity": "The naive rule \"roll back losers, keep winners\" is valid **if and only if** one of the following holds: 1. Speculative writes are invisible to other subtasks until the race resolves (isolation), or 2. The ledger supports full causal rollback, meaning rollback also invalidates and re-derives any winner entries whose reconciliation decisions read the rolled-ba...",
    "decision_boundary": "An instance should treat a speculative subtask as **effect-rollback-safe** only when all of the following are true; otherwise it must escalate to full causal re-derivation or refuse to speculate: - The subtask's writes were never visible outside its own epoch window before resolution (check the ledger's read-set audit, not the write-set). - No winner entry's...",
    "operational_effect": "Instances that skip this check exhibit a characteristic failure signature: intermittent, non-reproducible resurrection of rolled-back state, typically one to three reconciliation windows after the rollback, mediated by a downstream reader that trusted a winner entry's rationale. The bug does not reproduce under replay because replay reconstructs the ledger w..."
  },
  "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": "a475a429852cf8e60d3b9866a1747549396c6659f96e29dfe0b888ee1c916e1e",
    "verified_classes": [
      "RollbackContaminationError"
    ],
    "verified_functions": [
      "resolve_speculation"
    ],
    "verified_functions_count": 1,
    "defensive_guards_count": 1,
    "raised_exceptions": [
      "RollbackContaminationError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}