fix: let requireMentionInThread both relax and tighten the base setting

Remove the `requireMention &&` guard so requireMentionInThread works
bidirectionally: a group with requireMention: false can now set
requireMentionInThread: true to re-enable the mention requirement
for thread replies specifically.

Add test for the tightening edge case.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

extensions/feishu/src/policy.test.ts

@@ -163,6 +163,17 @@ describe("feishu policy", () => {
       ).toEqual({ requireMention: true });
     });
 
+    it("requireMentionInThread tightens when base requireMention is false", () => {
+      expect(
+        resolveFeishuReplyPolicy({
+          isDirectMessage: false,
+          isThreadReply: true,
+          globalConfig: { requireMention: false } as FeishuConfig,
+          groupConfig: { requireMentionInThread: true } as FeishuGroupConfig,
+        }),
+      ).toEqual({ requireMention: true });
+    });
+
     it("does not apply thread override for non-thread messages", () => {
       expect(
         resolveFeishuReplyPolicy({

extensions/feishu/src/policy.ts

@@ -116,7 +116,7 @@ export function resolveFeishuReplyPolicy(params: {
   const requireMention =
     params.groupConfig?.requireMention ?? params.globalConfig?.requireMention ?? true;
 
-  if (requireMention && params.isThreadReply) {
+  if (params.isThreadReply) {
     const threadOverride =
       params.groupConfig?.requireMentionInThread ?? params.globalConfig?.requireMentionInThread;
     if (threadOverride !== undefined) {