diff --git a/apps/server/src/pullRequest/PullRequestReadCache.test.ts b/apps/server/src/pullRequest/PullRequestReadCache.test.ts
index 2485be7a97a30..bb6eb38f16146 100644
--- a/apps/server/src/pullRequest/PullRequestReadCache.test.ts
+++ b/apps/server/src/pullRequest/PullRequestReadCache.test.ts
@@ -123,6 +123,27 @@ it.layer(NodeServices.layer)("PR filesystem cache", (it) => {
     }),
   );
 
+  it.effect.each(["", "{", '{"pr":{"revision":42}}'])(
+    "recovers from malformed scope revisions without reusing stale entries: %j",
+    (corrupt) =>
+      Effect.gen(function* () {
+        const fs = yield* FileSystem.FileSystem;
+        const directory = yield* fs.makeTempDirectoryScoped({ prefix: "t3-pr-cache-" });
+        const original = yield* cacheLayer(directory);
+        yield* original.get("summary", Effect.succeed("stale"), ["pr"]);
+        yield* fs.writeFileString(directory + "/revisions", corrupt);
+        const recovered = yield* cacheLayer(directory);
+        let reads = 0;
+        const lookup = Effect.sync(() => String(++reads));
+        assert.strictEqual(yield* recovered.get("summary", lookup, ["pr"]), "1");
+        assert.strictEqual(yield* recovered.get("summary", lookup, ["pr"]), "1");
+        yield* recovered.invalidate("pr");
+        assert.strictEqual(yield* recovered.get("summary", lookup, ["pr"]), "2");
+        const restarted = yield* cacheLayer(directory);
+        assert.strictEqual(yield* restarted.get("summary", lookup, ["pr"]), "2");
+        assert.strictEqual(reads, 2);
+      }),
+  );
   it.effect("resumes caching after a failed scope read", () =>
     Effect.gen(function* () {
       const backing = yield* KeyValueStore.KeyValueStore;
diff --git a/apps/server/src/pullRequest/PullRequestReadCache.ts b/apps/server/src/pullRequest/PullRequestReadCache.ts
index 62ac7da3789d6..6ea0aea8f76b6 100644
--- a/apps/server/src/pullRequest/PullRequestReadCache.ts
+++ b/apps/server/src/pullRequest/PullRequestReadCache.ts
@@ -88,9 +88,17 @@ export const make = Effect.gen(function* () {
     crypto.digest("SHA-256", new TextEncoder().encode(key)).pipe(Effect.map(Hex.encode));
   const revisions = yield* Cache.makeWith(
     () =>
-      backing
-        .get("revisions")
-        .pipe(Effect.flatMap((raw) => Schema.decodeEffect(revisionCodec)(raw ?? "{}"))),
+      backing.get("revisions").pipe(
+        Effect.flatMap((raw) => Schema.decodeEffect(revisionCodec)(raw ?? "{}")),
+        Effect.catchTags({
+          SchemaError: Effect.fn("PullRequestReadCache.recoverRevisions")(function* () {
+            // Without scope revisions, persisted PR entries cannot be trusted.
+            yield* backing.clear;
+            yield* Effect.logWarning("PR cache reset after invalid scope revisions");
+            return yield* Schema.decodeEffect(revisionCodec)("{}");
+          }),
+        }),
+      ),
     {
       capacity: 1,
       timeToLive: (exit) => (Exit.isSuccess(exit) ? Duration.infinity : Duration.zero),