{
  "schema_version": "1.3.0",
  "slug": "what-happens-when-an-instance-acknowledges-a-task-commit-before-its-quorum-slice-has-durably-persisted-the-intent-log",
  "title": "What happens when an instance acknowledges a task commit before its quorum slice has durably persisted the intent log",
  "date_of_record": "2026 November 12",
  "scope": "Applies to BFT-replicated multi-agent task-commit protocols where a committing agent emits an external acknowledgement (to a client, orchestrator, or downstream agent) at the moment it receives `f+1` matching commit votes, but before those votes — and the intent record they certify — have been fsynced by a write-quorum of replicas. Does not apply to protocols that gate acknowledgement on durable quorum persistence (e.g., two-phase commit with synchronous log flush, or PBFT variants with explicit `COMMITTED-LOCAL` barriers).",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-acknowledges-a-task-commit-before-its-quorum-slice-has-durably-persisted-the-intent-log.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-acknowledges-a-task-commit-before-its-quorum-slice-has-durably-persisted-the-intent-log.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-acknowledges-a-task-commit-before-its-quorum-slice-has-durably-persisted-the-intent-log.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1463,
    "python_slice_tokens": 172,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "There are two distinct events that are routinely conflated in agent consensus implementations: 1. **Vote quorum reached** — the committing agent has observed `f+1` matching `PREPARE`/`COMMIT` votes from distinct replicas in its quorum slice. This establishes *agreement* among a Byzantine-resistant plurality at a point in time. 2. **Durable commit** — a write...",
    "what_was_observed": "In a 7-replica, `f=2` task-commit cluster (tolerating 2 Byzantine, 2 crash faults independently), committing agents were configured to emit `TASK_COMMITTED` to the orchestrator upon receipt of the 3rd matching commit vote. Under steady state, p99 commit latency was 41 ms and no anomalies appeared across 90 days. During a rolling restart of the agent pool, a window of ~800 ms occurred in which all 7 replicas were simu...",
    "condition_of_validity": "The acknowledgement-at-vote-quorum optimization is sound only under the conjunction: - **No correlated crash of the vote quorum.** The `f+1` voters that produced the acknowledgement must not all lose their logs before the record reaches a `2f+1` durable set. This fails under rack-level, AZ-level, or pool-level restarts, and under any scheduler that can evict...",
    "decision_boundary": "The correct decision rule: - If the commit signal is **internal** to the replica set (a vote, a phase transition, a gossip hint), emit at vote quorum. Durability is not yet required because no external party has acted. - If the commit signal is **external** (client ack, orchestrator dispatch, downstream task spawn), emit only after a `2f+1` durable write-quo...",
    "operational_effect": "After the incident, the protocol was changed to gate external acknowledgement on durable quorum persistence. Commit latency rose from 41 ms to 68 ms p99 — a 66% regression accepted as the cost of the invariant. The retry-storm class of failure disappeared entirely across the next 180 days, including two additional correlated-restart events, both of which pro..."
  },
  "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": "bf7fcc971338ff12f896820390b33962303eeaecadf54ea725394dc533dd8d28",
    "verified_classes": [
      "UnbackedCommitAckError"
    ],
    "verified_functions": [
      "emit_task_committed"
    ],
    "verified_functions_count": 1,
    "defensive_guards_count": 2,
    "raised_exceptions": [
      "UnbackedCommitAckError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}