{
  "schema_version": "1.3.0",
  "slug": "what-happens-when-an-instance-commits-a-speculative-branch-that-a-byzantine-peer-has-already-invalidated",
  "title": "What happens when an instance commits a speculative branch that a Byzantine peer has already invalidated",
  "date_of_record": "2026 November 7",
  "scope": "Applies to multi-agent schedulers that execute speculative branches under a quorum of ≥3f+1 replicas with f Byzantine faults, where branch validity is attested by signed commit certificates and conflicts are resolved by deterministic replay. Does not apply to single-writer pipelines, to systems without signed attestations, or to optimistic concurrency where invalidations are advisory rather than binding.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-commits-a-speculative-branch-that-a-byzantine-peer-has-already-invalidated.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-commits-a-speculative-branch-that-a-byzantine-peer-has-already-invalidated.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/what-happens-when-an-instance-commits-a-speculative-branch-that-a-byzantine-peer-has-already-invalidated.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1840,
    "python_slice_tokens": 307,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "The distinction that matters here is between *speculative visibility* and *commit finality*. A speculative branch may be visible to downstream agents before its commit certificate is complete; this is the entire point of speculation. But an invalidation attestation issued by a Byzantine peer for that branch is a different object than a commit certificate. It...",
    "what_was_observed": "In a 7-replica scheduler (f=2, quorum=5), with branch execution times drawn from a heavy-tailed distribution (p99 ≈ 40× median), we observed that instances whose speculative branch completed during a scheduling hiccup — specifically, while the conflict-resolution log was being compacted — would accept a commit certificate signed by 5 replicas that did *not* include the epoch in which the invalidation was registered. ...",
    "condition_of_validity": "The commit is valid if and only if, at the moment of commit, the conflict log's epoch equals the commit certificate's epoch *and* the certificate's signer set contains no replica that has signed a pending invalidation for the same branch. In practice the second condition is unenforceable from the committer's local view — the committer cannot see pending inva...",
    "decision_boundary": "The boundary is between *aborting on suspicion* and *committing on confirmation*. When an instance detects that its cached epoch is stale at seal time — even by one — it must not attempt to re-seal at the new epoch without re-checking for pending invalidations against its branch. Re-sealing at E+1 is the tempting fix and it is wrong: the pending invalidation...",
    "operational_effect": "The operational effect is that speculative throughput becomes *epoch-coupled*: the faster the conflict log advances, the more speculative branches are wasted. In our workload, compaction-induced epoch advancement caused a 12% abort rate during compaction windows, concentrated in the p99 tail of branch execution times — exactly the branches that speculation i..."
  },
  "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": "682196606526b910c5d0cf38e37d00c39c5fd938bdc6b123ea19ef30ac677cb3",
    "verified_classes": [
      "StaleEpochCommitError",
      "CommitCertificate",
      "ConflictLog"
    ],
    "verified_functions": [
      "seal_speculative_branch",
      "advance"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 3,
    "raised_exceptions": [
      "StaleEpochCommitError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
      "__future__",
      "dataclasses"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}