fix(fishing): clear stale sessions for deleted threads

src/services/FishingService.ts

@@ -148,7 +148,7 @@ export class FishingService {
     }
 
     const userKey = this.getUserKey(interaction.guildId, interaction.user.id);
-    const existing = this.sessionsByUser.get(userKey);
+    const existing = await this.getActiveSession(userKey);
     if (existing) {
       return { thread: existing.thread, existed: true };
     }
@@ -170,7 +170,7 @@ export class FishingService {
       return false;
     }
 
-    const session = this.sessionsByUser.get(this.getUserKey(interaction.guildId, interaction.user.id));
+    const session = await this.getActiveSession(this.getUserKey(interaction.guildId, interaction.user.id));
     if (!session) {
       const thread = await this.findOwnedFishingThread(interaction);
       if (!thread) {
@@ -394,6 +394,39 @@ export class FishingService {
     }
   }
 
+  private static async getActiveSession(userKey: string) {
+    const session = this.sessionsByUser.get(userKey);
+    if (!session) {
+      return null;
+    }
+
+    if (await this.isSessionStale(session)) {
+      this.clearStaleSession(session);
+      return null;
+    }
+
+    return session;
+  }
+
+  private static async isSessionStale(session: FishingSession) {
+    try {
+      await session.thread.fetch();
+      await session.controlMessage.fetch();
+      return false;
+    } catch (error) {
+      logger.info(
+        `[Fishing] Clearing stale session for ${session.userId} in thread ${session.threadId}: ${error instanceof Error ? error.message : String(error)}`,
+      );
+      return true;
+    }
+  }
+
+  private static clearStaleSession(session: FishingSession) {
+    this.clearTick(session);
+    this.sessionsByUser.delete(this.getUserKey(session.guildId, session.userId));
+    this.sessionsByThread.delete(session.threadId);
+  }
+
   private static async deleteThread(thread: ThreadChannel) {
     try {
       await thread.delete();