fix: reject throttler queue overflow

core/src/utils/throttler.ts

@@ -22,12 +22,10 @@ export class Throttler {
     }
 
     async throttle(cost: number = 1): Promise<void> {
-        return new Promise<void>((resolve) => {
+        return new Promise<void>((resolve, reject) => {
             if (this.queue.length >= this.maxQueueDepth) {
-                const dropped = this.queue.shift();
-                if (dropped) {
-                    dropped.resolve();
-                }
+                reject(new Error(`Throttler queue full (max depth ${this.maxQueueDepth})`));
+                return;
             }
             this.queue.push({ resolve, cost });
             if (!this.running) {

core/test/utils/throttler.test.ts

@@ -0,0 +1,24 @@
+import { Throttler } from '../../src/utils/throttler';
+
+describe('Throttler', () => {
+    it('rejects new requests instead of silently resolving the oldest queued waiter', async () => {
+        const throttler = new Throttler({
+            refillRate: 1,
+            capacity: 1,
+            delay: 1,
+            maxQueueDepth: 1,
+        });
+
+        let oldestResolved = false;
+        (throttler as any).queue.push({
+            resolve: () => {
+                oldestResolved = true;
+            },
+            cost: 1,
+        });
+
+        await expect(throttler.throttle(1)).rejects.toThrow(/queue full/i);
+        expect(oldestResolved).toBe(false);
+        expect((throttler as any).queue).toHaveLength(1);
+    });
+});