test: add persistent replay ledger scaffold

Author: LalaSkye

enterprise-execution-readiness/adapters/replay_ledger.py

@@ -0,0 +1,39 @@
+"""
+Persistent replay ledger scaffold.
+
+This is an in-memory replay surface for deterministic refusal replay tests.
+It is not a production persistence layer.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+from typing import Dict, List
+
+
+@dataclass
+class ReplayLedgerEntry:
+    nonce: str
+    decision_id: str
+    result_code: str
+
+
+@dataclass
+class ReplayLedger:
+    entries: List[ReplayLedgerEntry] = field(default_factory=list)
+    index: Dict[str, ReplayLedgerEntry] = field(default_factory=dict)
+
+    def record(self, *, nonce: str, decision_id: str, result_code: str) -> None:
+        entry = ReplayLedgerEntry(
+            nonce=nonce,
+            decision_id=decision_id,
+            result_code=result_code,
+        )
+        self.entries.append(entry)
+        self.index[nonce] = entry
+
+    def contains(self, nonce: str) -> bool:
+        return nonce in self.index
+
+    def count(self) -> int:
+        return len(self.entries)