Keep AMQP depth probes passive

Avoid declaring queues or ordering exchanges while reporting AMQP queue
depth.  Missing queues now count as zero while preserving the existing
channel recreation path for passive checks, and delayed queue tracking is
iterated without copying all keys first.

#748 (comment)
#748 (comment)

Assisted-by: Codex:gpt-5.5

Author: dahlia

packages/amqp/src/mq.ts

@@ -398,30 +398,37 @@ export class AmqpMessageQueue implements MessageQueue {
         // The channel can already be closed by a failed passive queue check.
       }
     };
+    const checkQueue = async (
+      queueName: string,
+    ): Promise<number | undefined> => {
+      if (channel == null) channel = await this.#createDepthChannel();
+      try {
+        return (await channel.checkQueue(queueName)).messageCount;
+      } catch (error) {
+        if (!isQueueNotFoundError(error)) {
+          throw error;
+        }
+        await closeChannel();
+        channel = await this.#createDepthChannel();
+        return undefined;
+      }
+    };
     try {
-      await this.#prepareQueue(channel);
-      await this.#prepareOrdering(channel);
-
-      let ready = (await channel.checkQueue(this.#queue)).messageCount;
+      let ready = (await checkQueue(this.#queue)) ?? 0;
       if (this.#ordering != null) {
         for (let i = 0; i < this.#ordering.partitions; i++) {
-          ready += (await channel.checkQueue(this.#getOrderingQueueName(i)))
-            .messageCount;
+          ready += (await checkQueue(this.#getOrderingQueueName(i))) ?? 0;
         }
       }
 
       let delayed = 0;
       this.#pruneDelayedQueues();
-      for (const queue of [...this.#delayedQueues.keys()]) {
-        try {
-          delayed += (await channel.checkQueue(queue)).messageCount;
-        } catch (error) {
-          if (!isQueueNotFoundError(error)) {
-            throw error;
-          }
+      for (const queue of this.#delayedQueues.keys()) {
+        const messageCount = await checkQueue(queue);
+        if (messageCount == null) {
           this.#delayedQueues.delete(queue);
-          await closeChannel();
-          channel = await this.#createDepthChannel();
+        } else {
+          delayed += messageCount;
         }
       }