Discussion only open while a study is active; v2.11.1

- Community posts, replies, likes and lesson comments are refused (403) for finished and planned studies
- Reading a closed study's community/comments returns an empty list with closed:true
- Discussion hub lists only active studies; community page shows a closed notice
- Lesson page hides Lesson Discussion, 'Discuss this lesson' and 'Go to Community' for inactive studies; Community buttons hidden on study/dashboard pages
- Tests for isStudyDiscussionOpen

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

server/routes/study-data.js

@@ -12,6 +12,8 @@ import {
   getCommunityDisplayName,
   getAccessibleStudySlugs,
   markStudyCompletedIfDone,
+  isStudyDiscussionOpen,
+  DISCUSSION_CLOSED_MESSAGE,
 } from '../study-helpers.js'
 import { state } from '../state.js'
 import {
@@ -368,6 +370,11 @@ export function register(app) {
       return
     }
 
+    if (!isStudyDiscussionOpen(studySlug)) {
+      res.json({ studySlug, posts: [], closed: true, message: DISCUSSION_CLOSED_MESSAGE })
+      return
+    }
+
     const posts = state.studyCommunityPosts
       .filter(post => post.studySlug === studySlug)
       .sort((a, b) => new Date(b.createdAt).getTime() - new Date(a.createdAt).getTime())
@@ -413,6 +420,11 @@ export function register(app) {
       return
     }
 
+    if (!isStudyDiscussionOpen(studySlug)) {
+      res.status(403).json({ message: DISCUSSION_CLOSED_MESSAGE, closed: true })
+      return
+    }
+
     const now = new Date().toISOString()
     const authorName = getCommunityDisplayName(user)
     const post = {
@@ -455,6 +467,11 @@ export function register(app) {
       return
     }
 
+    if (!isStudyDiscussionOpen(post.studySlug)) {
+      res.status(403).json({ message: DISCUSSION_CLOSED_MESSAGE, closed: true })
+      return
+    }
+
     const reply = {
       id: randomUUID(),
       authorUserId: user.id,
@@ -480,6 +497,9 @@ export function register(app) {
     if (!hasStudyAccess(user, post.studySlug)) {
       res.status(403).json({ message: 'Please enroll in this study to like posts.' }); return
     }
+    if (!isStudyDiscussionOpen(post.studySlug)) {
+      res.status(403).json({ message: DISCUSSION_CLOSED_MESSAGE, closed: true }); return
+    }
     if (!Array.isArray(post.likedBy)) post.likedBy = []
     const idx = post.likedBy.indexOf(user.id)
     if (idx === -1) {