Discussion stays open for finished studies; only planned studies are closed; v2.11.2

A finished study is just no longer the main study, so students who take it later still need discussion.

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

server/study-helpers.js

@@ -225,17 +225,18 @@ export async function backfillCompletedStudies() {
   return updated
 }
 
-// Discussion (community posts, replies, likes and lesson comments) is only open while a
-// study is active. Finished and planned studies are closed.
+// Discussion (community posts, replies, likes and lesson comments) is open for any study that
+// has started: the current study and finished ones, so students who take a study later can
+// still talk with each other. Only planned studies (not started yet) are closed.
 export function isStudyDiscussionOpen(studySlug) {
   const normalized = normalizeStudySlug(studySlug)
   const studies = state.cachedSiteContent?.studies
   if (!normalized || !Array.isArray(studies)) return false
   const study = studies.find(item => normalizeStudySlug(item?.slug) === normalized)
-  return Boolean(study) && getEffectiveStudyStatus(study) === 'active'
+  return Boolean(study) && getEffectiveStudyStatus(study) !== 'planned'
 }
 
-export const DISCUSSION_CLOSED_MESSAGE = 'Discussion is only open while a study is active.'
+export const DISCUSSION_CLOSED_MESSAGE = 'Discussion opens once this study has started.'
 
 export function findStudyUserById(userId) {
   if (typeof userId !== 'string' || !userId.trim()) return undefined