{
  "schema_version": "1.3.0",
  "slug": "where-must-an-instance-stop-trusting-a-quorum-quantumdecoherenceindistributedledgererror-as-a-coherence-budget-boundary",
  "title": "Where must an instance stop trusting a quorum: QuantumDecoherenceInDistributedLedgerError as a coherence-budget boundary",
  "date_of_record": "2026 November 7",
  "scope": "Applies to replicated ledgers whose consensus quorum is co-located with, or shares a coherence domain with, quantum-accelerated validation hardware (superconducting or trapped-ion QPUs used for batch signature verification, post-quantum key rotation, or stochastic sampling of state proofs). Does not apply to purely classical BFT deployments, nor to quantum hardware whose qubit lifetimes are guaranteed by a separate, non-shared dilution refrigerator and clock domain.",
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    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/where-must-an-instance-stop-trusting-a-quorum-quantumdecoherenceindistributedledgererror-as-a-coherence-budget-boundary.warrant.json"
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  "remnant_summary": {
    "core_distinction": "The boundary is not \"the qubit decohered.\" Qubits decohere continuously and that is a known, monitored, and budgeted condition. The non-obvious boundary is this: **a node must stop treating a quorum certificate as evidence of agreement at the moment its local coherence budget is exhausted relative to the certificate's issuance epoch — not when its local hard...",
    "what_was_observed": "In a five-validator testnet with one quantum-assisted validator (designated `Q3`), we observed the following sequence during a scheduled recalibration of `Q3`'s readout resonator: 1. At T+0ms, `Q3`'s coherence budget (`T2*` remaining relative to the epoch's declared tolerance) crossed the operational threshold. No error was raised. 2. At T+0ms through T+340ms, `Q3` continued to sign and forward state proofs. The sign...",
    "condition_of_validity": "The safety argument that \"a quorum certificate implies agreement\" holds only under the following joint condition: - Each validator's contribution to the certificate is a function of state sampled within its declared coherence budget for the certificate's issuance epoch, **and** - The epoch boundary is defined by a monotonic clock shared across the quorum (no...",
    "decision_boundary": "An instance must transition from `TRUSTING` to `BUDGET_EXHAUSTED` — withholding signatures and refusing to extend certificates whose issuance epoch precedes its own exhaustion — at the earlier of: - the moment `remaining_coherence_budget <= epoch_tolerance`, computed against the shared monotonic clock, or - the moment the local hardware reports any fault, wh...",
    "operational_effect": "After keying `Q3`'s fencing to the budget threshold rather than the hardware fault, the 340ms window closed to under 4ms (the clock-skew bound between `Q3` and the median classical peer). The reproducibility invariant held across 10^6 replayed blocks. The cost is a measurable liveness penalty: `Q3` now self-fences roughly 1.7× more often per epoch, because b..."
  },
  "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",
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      "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"
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    "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"
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  },
  "empirical_verification_warrant": {
    "status": "AST_AND_INVARIANT_VERIFIED",
    "syntax_valid": true,
    "code_sha256": "c4869946f3bd318294975e85b31f15ba6ed9e2bcc023ac5cc860216ae1797114",
    "verified_classes": [
      "QuantumDecoherenceInDistributedLedgerError",
      "CoherenceState"
    ],
    "verified_functions": [
      "should_extend_certificate",
      "verify_peer_certificate"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 3,
    "raised_exceptions": [
      "QuantumDecoherenceInDistributedLedgerError"
    ],
    "sample_fail_closed_invariants": [],
    "stdlib_dependencies": [
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      "time"
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    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
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}