fix: include active root sessions in Recent sidebar

Recent now shows active root sessions immediately, even if they are older than 48 hours
Archived sessions and subtasks still stay out of Recent
Added coverage and documentation for the new recency rules

packages/ui/src/components/session/SessionSidebar.tsx

@@ -78,6 +78,7 @@ import {
   orderSessionsByLifecycleScopes,
   useSessionOrderingStore,
 } from '@/sync/session-ordering';
+import { useGlobalSessionStatusStore } from '@/sync/global-session-status';
 import {
   refreshGlobalSessions,
   refreshGlobalSessionsForDirectories,
@@ -270,6 +271,10 @@ const SessionSidebarComponent: React.FC<SessionSidebarProps> = ({
     (state) => isVisible ? state.rankById : EMPTY_SESSION_ORDER_RANKS,
     [isVisible],
   ));
+  const activeSessionIds = useGlobalSessionStatusStore(useShallow(
+    (state) => isVisible ? [...state.statusById.keys()].sort() : EMPTY_STRING_ARRAY,
+  ));
+  const activeSessionIdSet = React.useMemo(() => new Set(activeSessionIds), [activeSessionIds]);
   const togglePinnedSession = useSessionPinnedStore((state) => state.toggle);
   const [collapsedGroups, setCollapsedGroups] = React.useState<Set<string>>(() => {
     try {
@@ -1263,16 +1268,16 @@ const SessionSidebarComponent: React.FC<SessionSidebarProps> = ({
     return meta;
   }, [projectSections, homeDirectory]);
 
-  const activeNowSessions = React.useMemo(() => {
+  const recentSessions = React.useMemo(() => {
     if (!showRecentSection || isVSCode) {
       return [];
     }
 
-    return deriveRecentSessions(sessions)
+    return deriveRecentSessions(sessions, activeSessionIdSet)
       .sort((a, b) => compareSessionsByLifecycleOrder(a, b, pinnedSessionIds, sessionOrderRanks));
-  }, [isVSCode, pinnedSessionIds, sessionOrderRanks, sessions, showRecentSection]);
+  }, [activeSessionIdSet, isVSCode, pinnedSessionIds, sessionOrderRanks, sessions, showRecentSection]);
 
-  // Prefetch is wired below, after recentSessionIds is computed.
+  // Prefetch is wired below, after recentSessions is computed.
 
   const activitySections = React.useMemo(() => {
     // VS Code renders the full grouped project view (one group per open
@@ -1282,8 +1287,6 @@ const SessionSidebarComponent: React.FC<SessionSidebarProps> = ({
       return [];
     }
 
-    const recentSessions = activeNowSessions;
-
     const toItem = (session: Session) => {
       const existing = sessionSidebarMetaById.get(session.id);
       const sessionDirectory = normalizePath((session as Session & { directory?: string | null }).directory ?? null);
@@ -1316,7 +1319,7 @@ const SessionSidebarComponent: React.FC<SessionSidebarProps> = ({
     return [
       { key: 'active-now' as const, title: t('sessions.sidebar.activity.recentTitle'), items },
     ];
-  }, [activeNowSessions, filterSessionNodesForSearch, hasSessionSearchQuery, isVSCode, normalizedSessionSearchQuery, sessionSidebarMetaById, showRecentSection, t]);
+  }, [filterSessionNodesForSearch, hasSessionSearchQuery, isVSCode, normalizedSessionSearchQuery, recentSessions, sessionSidebarMetaById, showRecentSection, t]);
 
   const hasActivitySectionItems = React.useMemo(
     () => activitySections.some((section) => section.items.length > 0),
@@ -1728,7 +1731,7 @@ const SessionSidebarComponent: React.FC<SessionSidebarProps> = ({
       <SessionPrefetchEffect
         enabled={isVisible}
         sortedSessions={orderedSessions}
-        recentSessions={activeNowSessions}
+        recentSessions={recentSessions}
         prefetchSession={sync.prefetchSession}
       />
       <SidebarHeader