Fix discussion channel closure handling

plugin/hooks/before-model-resolve.ts

@@ -29,6 +29,9 @@ type BeforeModelResolveDeps = {
   pruneDecisionMap: () => void;
   shouldDebugLog: (config: DirigentConfig & DebugConfig, channelId?: string) => boolean;
   ensureTurnOrder: (api: OpenClawPluginApi, channelId: string) => Promise<void> | void;
+  discussionService?: {
+    isClosedDiscussion: (channelId: string) => boolean;
+  };
 };
 
 export function registerBeforeModelResolveHook(deps: BeforeModelResolveDeps): void {
@@ -47,6 +50,7 @@ export function registerBeforeModelResolveHook(deps: BeforeModelResolveDeps): vo
     pruneDecisionMap,
     shouldDebugLog,
     ensureTurnOrder,
+    discussionService,
   } = deps;
 
   api.on("before_model_resolve", async (event, ctx) => {
@@ -86,6 +90,15 @@ export function registerBeforeModelResolveHook(deps: BeforeModelResolveDeps): vo
 
     if (derived.channelId) {
       sessionChannelId.set(key, derived.channelId);
+      if (discussionService?.isClosedDiscussion(derived.channelId)) {
+        sessionAllowed.set(key, false);
+        api.logger.info(`dirigent: before_model_resolve forcing no-reply for closed discussion channel=${derived.channelId} session=${key}`);
+        return {
+          model: ctx.model,
+          provider: ctx.provider,
+          noReply: true,
+        };
+      }
     }
     const resolvedAccountId = resolveAccountId(api, ctx.agentId || "");
     if (resolvedAccountId) {