fix: dedupe inbound messages across providers

src/slack/monitor.ts

@@ -50,6 +50,7 @@ import {
   updateLastRoute,
 } from "../config/sessions.js";
 import { danger, logVerbose, shouldLogVerbose } from "../globals.js";
+import { createDedupeCache } from "../infra/dedupe.js";
 import { enqueueSystemEvent } from "../infra/system-events.js";
 import { getChildLogger } from "../logging.js";
 import { type FetchLike, fetchRemoteMedia } from "../media/fetch.js";
@@ -516,24 +517,11 @@ export async function monitorSlackProvider(opts: MonitorSlackOpts = {}) {
     }
   >();
   const userCache = new Map<string, { name?: string }>();
-  const seenMessages = new Map<string, number>();
+  const seenMessages = createDedupeCache({ ttlMs: 60_000, maxSize: 500 });
 
   const markMessageSeen = (channelId: string | undefined, ts?: string) => {
     if (!channelId || !ts) return false;
-    const key = `${channelId}:${ts}`;
-    if (seenMessages.has(key)) return true;
-    seenMessages.set(key, Date.now());
-    if (seenMessages.size > 500) {
-      const cutoff = Date.now() - 60_000;
-      for (const [entry, seenAt] of seenMessages) {
-        if (seenAt < cutoff || seenMessages.size > 450) {
-          seenMessages.delete(entry);
-        } else {
-          break;
-        }
-      }
-    }
-    return false;
+    return seenMessages.check(`${channelId}:${ts}`);
   };
 
   const app = new App({