diff --git a/.jules/bolt.md b/.jules/bolt.md
index d54cf10fc..e9018ad96 100644
--- a/.jules/bolt.md
+++ b/.jules/bolt.md
@@ -61,3 +61,8 @@
 ## 2026-07-13 - Array.from mapping optimization
 **Learning:** Using `Array.from({ length: N }).map(...)` creates an intermediate array of `undefined` values which requires memory allocation and garbage collection, adding O(N) unnecessary overhead in frequently re-rendered UI components.
 **Action:** Use `Array.from({ length: N }, (_, index) => ...)` to map elements directly during array creation, avoiding intermediate allocations.
+
+## 2026-07-20 - Avoid Array.every() for large byte array validation
+
+**Learning:** Validating large payloads over the IPC bridge with `.every()` creates significant O(N) intermediate callback allocations and Garbage Collection overhead on the critical path.
+**Action:** Replace `.every()` with a standard `for...of` loop with an early `break` for O(1) memory and substantially faster checks for malformed payload chunks.
diff --git a/apps/desktop/src/features/score/scoreStorage.test.ts b/apps/desktop/src/features/score/scoreStorage.test.ts
index 0feec199e..123c654eb 100644
--- a/apps/desktop/src/features/score/scoreStorage.test.ts
+++ b/apps/desktop/src/features/score/scoreStorage.test.ts
@@ -32,4 +32,18 @@ describe("scoreStorage bridge resolution", () => {
       BRIDGE_UNAVAILABLE_MESSAGE
     );
   });
+
+  it("fails when the response array contains non-number elements", async () => {
+    const tauriWindow = window as TauriWindow;
+    tauriWindow.__TAURI_INVOKE__ = async (command: string) => {
+      if (command === "read_score_pdf") {
+        return [1, 2, "not a number", 4];
+      }
+      return null;
+    };
+
+    await expect(readScorePdf("project-1", "score-1")).rejects.toThrow(
+      "Invalid score bridge response"
+    );
+  });
 });
diff --git a/apps/desktop/src/features/score/scoreStorage.ts b/apps/desktop/src/features/score/scoreStorage.ts
index 492f12591..c5feba9a8 100644
--- a/apps/desktop/src/features/score/scoreStorage.ts
+++ b/apps/desktop/src/features/score/scoreStorage.ts
@@ -91,8 +91,17 @@ export async function readScorePdf(projectId: string, scoreId: string): Promise<
   if (response instanceof ArrayBuffer) {
     return new Uint8Array(response);
   }
-  if (Array.isArray(response) && response.every((byte) => typeof byte === "number")) {
-    return Uint8Array.from(response as number[]);
+  if (Array.isArray(response)) {
+    let isValid = true;
+    for (const byte of response) {
+      if (typeof byte !== "number") {
+        isValid = false;
+        break;
+      }
+    }
+    if (isValid) {
+      return Uint8Array.from(response as number[]);
+    }
   }
 
   throw new Error(INVALID_RESPONSE_MESSAGE);