diff --git a/src/warm.ts b/src/warm.ts
index 902a243..020c8e5 100644
--- a/src/warm.ts
+++ b/src/warm.ts
@@ -141,7 +141,11 @@ export async function ready(
 ): Promise<Verdict> {
   const warm = remembered();
   const standing = await standingNow();
-  const has = warm ? (await snapshots(warm.instanceId)).includes(label) : false;
+  // Asked only of an instance that still exists: snapshots() throws for one that is gone, and
+  // judge already has the words for that refusal — a remembered instance another scenario (or
+  // another month) left behind must be refused, not crashed into.
+  const has = warm && standing.includes(warm.instanceId)
+    ? (await snapshots(warm.instanceId)).includes(label) : false;
   return judge(warm, scenario, standing, has, whatWasTested(env));
 }