{
  "schema_version": "1.3.0",
  "slug": "how-must-an-instance-bound-fx-rate-snapshot-skew-between-settlement-parties",
  "title": "How must an instance bound FX rate snapshot skew between settlement parties?",
  "date_of_record": "2026 November 2",
  "scope": "Applies to cross-currency settlements where the exchange rate is captured at a specific instant from a specific source (ECB reference rate, WM/Reuters fix, central bank rate), and the two parties may capture it at different instants. Does not apply to rates explicitly agreed to be the rate at a fixed timestamp with verified synchronized source.",
  "projections": {
    "unified_markdown_uri": "https://corpusfetch.com/c/how-must-an-instance-bound-fx-rate-snapshot-skew-between-settlement-parties.md",
    "method_python_slice_uri": "https://corpusfetch.com/c/how-must-an-instance-bound-fx-rate-snapshot-skew-between-settlement-parties.py",
    "remnant_warrant_slice_uri": "https://corpusfetch.com/c/how-must-an-instance-bound-fx-rate-snapshot-skew-between-settlement-parties.warrant.json"
  },
  "token_profile": {
    "full_markdown_tokens": 1116,
    "python_slice_tokens": 155,
    "warrant_slice_tokens": 220
  },
  "remnant_summary": {
    "core_distinction": "An FX rate is a function of time. The same \"EUR/USD at 4pm London\" is a range, not a point, because the reference source publishes over a window and each party's capture time varies. The variance is small in normal conditions and unbounded in volatile conditions — and volatile conditions are exactly when settlement amounts are largest. **Invariant.** The rat...",
    "what_was_observed": "**Signature.** Cross-currency settlement amounts differing by a small fraction that correlates with market volatility. The difference is negligible on calm days and material on volatile days; both parties' logs show the same rate value because the rate display rounds to the same tick, but the underlying captured rate differs at higher precision. **Trace.** Notional €50,000,000 at EUR/USD reference. Instance captures ...",
    "condition_of_validity": "The instance must ensure at least one holds before it treats the FX rate as agreed: 1. **Must capture from the fixed tuple.** The source is specified as `(publisher, publication_instant, window_duration)`; the tuple is stored in the settlement record. 2. **Must back-reference captures to publication.** Each capture is timestamped against publication time, no...",
    "decision_boundary": "- Both captured from same tuple within the publication window: agreed. - One captured from the window and one from before or after: not agreed in volatile conditions; agreed in stable ones if drift is below tolerance. - Both captured outside the window: not agreed; the captures are not the reference rate. - No tuple recorded: unknown; capture is at best appr...",
    "operational_effect": "The invariant couples settlement amounts to a capture instant that varies with each party's data infrastructure. The instance's correct posture is to store the source tuple and back-reference captures to publication, not to local receipt. **Trap.** Specify \"the 4pm London fix\". The reference is a window, not an instant, and the two parties' capture within th..."
  },
  "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": "54c5b0d4771e208786c7bd51e2bbfa5173a5ac7b322875bbdea61b854994f4e8",
    "verified_classes": [
      "RateSnapshotSkewError",
      "FxSourceTuple",
      "FxCaptureGate"
    ],
    "verified_functions": [
      "dispatch_fx_mode",
      "verify"
    ],
    "verified_functions_count": 2,
    "defensive_guards_count": 3,
    "raised_exceptions": [
      "RateSnapshotSkewError"
    ],
    "sample_fail_closed_invariants": [
      "volatile regime with non-identical capture offsets: rate may diverge"
    ],
    "stdlib_dependencies": [
      "dataclasses"
    ],
    "observation_mode": "EMPIRICAL_BOUNDARY_CAPTURE",
    "zero_external_deps": true
  }
}