diff --git a/deploy/replay-verify.mjs b/deploy/replay-verify.mjs
new file mode 100644
index 0000000..c507b05
--- /dev/null
+++ b/deploy/replay-verify.mjs
@@ -0,0 +1,21 @@
+// Strict full-ledger replay: ANY refused command is a hard failure.
+import { readFileSync } from "fs";
+import { createGame, applyCommand } from "../packages/engine/src/game.ts";
+const lines = readFileSync(process.argv[2], "utf8").trim().split("\n").map((l) => JSON.parse(l));
+const meta = lines.find((l) => l.kind === "meta");
+const start = lines.find((l) => l.kind === "start");
+if (!start) {
+  console.log(`OK ${process.argv[2].split("/").pop()}: lobby only, nothing to replay`);
+  process.exit(0);
+}
+const joins = lines.filter((l) => l.kind === "join");
+const playerIds = [...new Set([meta.hostId, ...joins.map((j) => j.name)])];
+let { state } = createGame({ playerIds, seed: meta.seed, sets: start.expansion ? ["basic", "expansion1"] : ["basic"], colors: start.colors, deckRev: start.deckRev });
+let n = 0;
+for (const l of lines) {
+  if (l.kind !== "command") continue;
+  const r = applyCommand(state, l.playerId, l.command);
+  if (!r.ok) { console.log(`FAIL ${process.argv[2].split("/").pop()} seq ${l.seq}: ${r.error}`); process.exit(1); }
+  state = r.state; n++;
+}
+console.log(`OK ${process.argv[2].split("/").pop()}: ${n} commands replay clean`);
diff --git a/deploy/verify-ledgers.sh b/deploy/verify-ledgers.sh
new file mode 100755
index 0000000..821dc9a
--- /dev/null
+++ b/deploy/verify-ledgers.sh
@@ -0,0 +1,19 @@
+#!/bin/bash
+# Pre-deploy determinism check: fetch every production ledger and strictly
+# replay it against the LOCAL engine. Any refused command is a hard failure.
+# Run from the repo root before deploying any engine change.
+set -euo pipefail
+HOST="${1:-104.236.96.198}"
+TMP=$(mktemp -d)
+trap 'rm -rf "$TMP"' EXIT
+scp -q "root@$HOST:/var/lib/wizwar/rooms/*.jsonl" "$TMP/"
+fails=0
+for f in "$TMP"/*.jsonl; do
+  out=$(npx tsx deploy/replay-verify.mjs "$f" 2>&1 | tail -1)
+  case "$out" in
+    FAIL*) echo "$out"; fails=$((fails+1));;
+  esac
+done
+count=$(ls "$TMP" | wc -l | tr -d ' ')
+echo "--- $count ledgers checked, $fails failures"
+[ "$fails" -eq 0 ]