perf(quick-wins): batch collaborator resolution, debounce SSE refresh, loading states

- Eliminate N+1 on resolveCollaborator: add batchResolveCollaborators() in
  auth.ts (2 DB queries max regardless of session count), update all 4
  workshop services to use post-batch mapping
- Debounce router.refresh() in useLive.ts (300ms) to group simultaneous
  SSE events and avoid cascade re-renders
- Call cleanupOldEvents fire-and-forget in createEvent to purge old SSE
  events inline without blocking the response
- Add loading.tsx skeletons on /sessions and /users matching actual page
  layout (PageHeader + content structure)
- Lazy-load ShareModal via next/dynamic in BaseSessionLiveWrapper to reduce
  initial JS bundle

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

src/app/sessions/loading.tsx

@@ -0,0 +1,32 @@
+export default function SessionsLoading() {
+  return (
+    <main className="mx-auto max-w-7xl px-4">
+      {/* PageHeader skeleton */}
+      <div className="py-6 flex items-start justify-between gap-4">
+        <div className="flex items-center gap-3">
+          <div className="h-10 w-10 bg-card rounded-xl animate-pulse" />
+          <div className="space-y-2">
+            <div className="h-7 w-40 bg-card rounded animate-pulse" />
+            <div className="h-4 w-64 bg-card rounded animate-pulse" />
+          </div>
+        </div>
+        <div className="h-9 w-36 bg-card rounded-lg animate-pulse" />
+      </div>
+
+      <div className="space-y-6">
+        {/* Tabs skeleton */}
+        <div className="flex gap-2 pb-2">
+          {[120, 100, 110, 90, 105].map((w, i) => (
+            <div key={i} className="h-9 bg-card animate-pulse rounded-full" style={{ width: w }} />
+          ))}
+        </div>
+        {/* Cards grid skeleton */}
+        <div className="grid gap-4 md:grid-cols-2 lg:grid-cols-3">
+          {Array.from({ length: 6 }).map((_, i) => (
+            <div key={i} className="h-44 bg-card animate-pulse rounded-xl border border-border" />
+          ))}
+        </div>
+      </div>
+    </main>
+  );
+}

src/app/users/loading.tsx

@@ -0,0 +1,42 @@
+export default function UsersLoading() {
+  return (
+    <main className="mx-auto max-w-6xl px-4">
+      {/* PageHeader skeleton */}
+      <div className="py-6 flex items-start gap-3">
+        <div className="h-10 w-10 bg-card rounded-xl animate-pulse" />
+        <div className="space-y-2">
+          <div className="h-7 w-36 bg-card rounded animate-pulse" />
+          <div className="h-4 w-72 bg-card rounded animate-pulse" />
+        </div>
+      </div>
+
+      {/* Stats grid skeleton */}
+      <div className="mb-8 grid grid-cols-2 gap-4 sm:grid-cols-4">
+        {Array.from({ length: 4 }).map((_, i) => (
+          <div key={i} className="rounded-xl border border-border bg-card p-4 space-y-2 animate-pulse">
+            <div className="h-8 w-12 bg-muted/40 rounded" />
+            <div className="h-4 w-24 bg-muted/30 rounded" />
+          </div>
+        ))}
+      </div>
+
+      {/* User rows skeleton */}
+      <div className="space-y-3">
+        {Array.from({ length: 8 }).map((_, i) => (
+          <div key={i} className="flex items-center gap-4 rounded-xl border border-border bg-card p-4 animate-pulse">
+            <div className="h-12 w-12 rounded-full bg-muted/40 flex-shrink-0" />
+            <div className="flex-1 space-y-2 min-w-0">
+              <div className="h-4 w-32 bg-muted/40 rounded" />
+              <div className="h-3 w-48 bg-muted/30 rounded" />
+            </div>
+            <div className="hidden sm:flex gap-2">
+              <div className="h-6 w-16 bg-muted/30 rounded-full" />
+              <div className="h-6 w-16 bg-muted/30 rounded-full" />
+              <div className="h-6 w-16 bg-muted/30 rounded-full" />
+            </div>
+          </div>
+        ))}
+      </div>
+    </main>
+  );
+}

src/components/collaboration/BaseSessionLiveWrapper.tsx

@@ -1,10 +1,12 @@
 'use client';
 
 import { useState, useCallback } from 'react';
+import dynamic from 'next/dynamic';
 import { useLive, type LiveEvent } from '@/hooks/useLive';
 import { CollaborationToolbar } from './CollaborationToolbar';
-import { ShareModal } from './ShareModal';
 import type { ShareRole } from '@prisma/client';
+
+const ShareModal = dynamic(() => import('./ShareModal').then((m) => m.ShareModal), { ssr: false });
 import type { TeamWithMembers, Share } from '@/lib/share-utils';
 
 export type LiveApiPath = 'sessions' | 'motivators' | 'weather' | 'year-review' | 'weekly-checkin' | 'gif-mood';

src/hooks/useLive.ts

@@ -38,6 +38,7 @@ export function useLive({
   const router = useRouter();
   const eventSourceRef = useRef<EventSource | null>(null);
   const reconnectTimeoutRef = useRef<NodeJS.Timeout | null>(null);
+  const refreshTimeoutRef = useRef<NodeJS.Timeout | null>(null);
   const reconnectAttemptsRef = useRef(0);
   const onEventRef = useRef(onEvent);
   const currentUserIdRef = useRef(currentUserId);
@@ -88,8 +89,9 @@ export function useLive({
             setLastEvent(data);
             onEventRef.current?.(data);
 
-            // Refresh the page data when we receive an event from another user
+            // Debounce refresh to group simultaneous SSE events (~300ms window)
-            router.refresh();
+            if (refreshTimeoutRef.current) clearTimeout(refreshTimeoutRef.current);
+            refreshTimeoutRef.current = setTimeout(() => router.refresh(), 300);
           } catch (e) {
             console.error('Failed to parse SSE event:', e);
           }
@@ -126,6 +128,10 @@ export function useLive({
         clearTimeout(reconnectTimeoutRef.current);
         reconnectTimeoutRef.current = null;
       }
+      if (refreshTimeoutRef.current) {
+        clearTimeout(refreshTimeoutRef.current);
+        refreshTimeoutRef.current = null;
+      }
     };
   }, [sessionId, apiPath, enabled, router]);
 

src/services/auth.ts

@@ -74,6 +74,48 @@ export interface ResolvedCollaborator {
   } | null;
 }
 
+// Batch resolve multiple collaborator strings — 2 DB queries max regardless of count
+export async function batchResolveCollaborators(
+  collaborators: string[]
+): Promise<Map<string, ResolvedCollaborator>> {
+  if (collaborators.length === 0) return new Map();
+
+  const unique = [...new Set(collaborators.map((c) => c.trim()))];
+  const emails = unique.filter(isEmail).map((e) => e.toLowerCase());
+  const names = unique.filter((c) => !isEmail(c));
+
+  const [byEmail, byName] = await Promise.all([
+    emails.length > 0
+      ? prisma.user.findMany({
+          where: { email: { in: emails } },
+          select: { id: true, email: true, name: true },
+        })
+      : [],
+    names.length > 0
+      ? prisma.user.findMany({
+          where: { OR: names.map((n) => ({ name: { contains: n } })) },
+          select: { id: true, email: true, name: true },
+        })
+      : [],
+  ]);
+
+  const emailMap = new Map(byEmail.map((u) => [u.email.toLowerCase(), u]));
+  const nameMap = new Map(
+    byName.filter((u) => u.name).map((u) => [u.name!.toLowerCase(), u])
+  );
+
+  const result = new Map<string, ResolvedCollaborator>();
+  for (const c of unique) {
+    if (isEmail(c)) {
+      result.set(c, { raw: c, matchedUser: emailMap.get(c.toLowerCase()) ?? null });
+    } else {
+      const match = nameMap.get(c.toLowerCase()) ?? null;
+      result.set(c, { raw: c, matchedUser: match });
+    }
+  }
+  return result;
+}
+
 // Resolve collaborator string to user - try email first, then name
 export async function resolveCollaborator(collaborator: string): Promise<ResolvedCollaborator> {
   const trimmed = collaborator.trim();

src/services/moving-motivators.ts

@@ -1,5 +1,5 @@
 import { prisma } from '@/services/database';
-import { resolveCollaborator } from '@/services/auth';
+import { resolveCollaborator, batchResolveCollaborators } from '@/services/auth';
 import { getTeamMemberIdsForAdminTeams } from '@/services/teams';
 import { createSessionPermissionChecks } from '@/services/session-permissions';
 import { createShareAndEventHandlers } from '@/services/session-share-events';
@@ -21,7 +21,7 @@ const motivatorInclude = {
 // ============================================
 
 export async function getMotivatorSessionsByUserId(userId: string) {
-  return mergeSessionsByUserId(
+  const sessions = await mergeSessionsByUserId(
     (uid) =>
       prisma.movingMotivatorsSession.findMany({
         where: { userId: uid },
@@ -33,14 +33,18 @@ export async function getMotivatorSessionsByUserId(userId: string) {
         where: { userId: uid },
         include: { session: { include: motivatorInclude } },
       }),
-    userId,
+    userId
-    (s) => resolveCollaborator(s.participant).then((r) => ({ resolvedParticipant: r }))
   );
+  const resolved = await batchResolveCollaborators(sessions.map((s) => s.participant));
+  return sessions.map((s) => ({
+    ...s,
+    resolvedParticipant: resolved.get(s.participant.trim()) ?? { raw: s.participant, matchedUser: null },
+  }));
 }
 
 /** Sessions owned by team members (where user is team admin) that are NOT shared with the user. */
 export async function getTeamCollaboratorSessionsForAdmin(userId: string) {
-  return fetchTeamCollaboratorSessions(
+  const sessions = await fetchTeamCollaboratorSessions(
     (teamMemberIds, uid) =>
       prisma.movingMotivatorsSession.findMany({
         where: { userId: { in: teamMemberIds }, shares: { none: { userId: uid } } },
@@ -48,9 +52,13 @@ export async function getTeamCollaboratorSessionsForAdmin(userId: string) {
         orderBy: { updatedAt: 'desc' },
       }),
     getTeamMemberIdsForAdminTeams,
-    userId,
+    userId
-    (s) => resolveCollaborator(s.participant).then((r) => ({ resolvedParticipant: r }))
   );
+  const resolved = await batchResolveCollaborators(sessions.map((s) => s.participant));
+  return sessions.map((s) => ({
+    ...s,
+    resolvedParticipant: resolved.get(s.participant.trim()) ?? { raw: s.participant, matchedUser: null },
+  }));
 }
 
 const motivatorByIdInclude = {

src/services/session-share-events.ts

@@ -131,14 +131,21 @@ export function createShareAndEventHandlers<TEventType extends string>(
       type: TEventType,
       payload: Record<string, unknown>
     ): Promise<SessionEventWithUser> {
-      return eventModel.create({
+      const event = await eventModel.create({
         data: {
           sessionId,
           userId,
           type,
           payload: JSON.stringify(payload),
         },
-      }) as Promise<SessionEventWithUser>;
+      });
+
+      // Fire-and-forget: purge old events without blocking the response
+      eventModel.deleteMany({ where: { createdAt: { lt: new Date(Date.now() - 24 * 60 * 60 * 1000) } } }).catch((err: unknown) => {
+        console.error('[cleanupOldEvents] Failed to purge old events:', err);
+      });
+
+      return event as SessionEventWithUser;
     },
 
     async getEvents(sessionId: string, since?: Date): Promise<SessionEventWithUser[]> {

src/services/sessions.ts

@@ -1,5 +1,5 @@
 import { prisma } from '@/services/database';
-import { resolveCollaborator } from '@/services/auth';
+import { resolveCollaborator, batchResolveCollaborators } from '@/services/auth';
 import { getTeamMemberIdsForAdminTeams } from '@/services/teams';
 import { createSessionPermissionChecks } from '@/services/session-permissions';
 import { createShareAndEventHandlers } from '@/services/session-share-events';
@@ -21,7 +21,7 @@ const sessionInclude = {
 // ============================================
 
 export async function getSessionsByUserId(userId: string) {
-  return mergeSessionsByUserId(
+  const sessions = await mergeSessionsByUserId(
     (uid) =>
       prisma.session.findMany({
         where: { userId: uid },
@@ -33,14 +33,18 @@ export async function getSessionsByUserId(userId: string) {
         where: { userId: uid },
         include: { session: { include: sessionInclude } },
       }),
-    userId,
+    userId
-    (s) => resolveCollaborator(s.collaborator).then((r) => ({ resolvedCollaborator: r }))
   );
+  const resolved = await batchResolveCollaborators(sessions.map((s) => s.collaborator));
+  return sessions.map((s) => ({
+    ...s,
+    resolvedCollaborator: resolved.get(s.collaborator.trim()) ?? { raw: s.collaborator, matchedUser: null },
+  }));
 }
 
 /** Sessions owned by team members (where user is team admin) that are NOT shared with the user. */
 export async function getTeamCollaboratorSessionsForAdmin(userId: string) {
-  return fetchTeamCollaboratorSessions(
+  const sessions = await fetchTeamCollaboratorSessions(
     (teamMemberIds, uid) =>
       prisma.session.findMany({
         where: { userId: { in: teamMemberIds }, shares: { none: { userId: uid } } },
@@ -48,9 +52,13 @@ export async function getTeamCollaboratorSessionsForAdmin(userId: string) {
         orderBy: { updatedAt: 'desc' },
       }),
     getTeamMemberIdsForAdminTeams,
-    userId,
+    userId
-    (s) => resolveCollaborator(s.collaborator).then((r) => ({ resolvedCollaborator: r }))
   );
+  const resolved = await batchResolveCollaborators(sessions.map((s) => s.collaborator));
+  return sessions.map((s) => ({
+    ...s,
+    resolvedCollaborator: resolved.get(s.collaborator.trim()) ?? { raw: s.collaborator, matchedUser: null },
+  }));
 }
 
 const sessionByIdInclude = {

src/services/weekly-checkin.ts

@@ -1,5 +1,5 @@
 import { prisma } from '@/services/database';
-import { resolveCollaborator } from '@/services/auth';
+import { resolveCollaborator, batchResolveCollaborators } from '@/services/auth';
 import { getTeamMemberIdsForAdminTeams } from '@/services/teams';
 import { createSessionPermissionChecks } from '@/services/session-permissions';
 import { createShareAndEventHandlers } from '@/services/session-share-events';
@@ -21,7 +21,7 @@ const weeklyCheckInInclude = {
 // ============================================
 
 export async function getWeeklyCheckInSessionsByUserId(userId: string) {
-  return mergeSessionsByUserId(
+  const sessions = await mergeSessionsByUserId(
     (uid) =>
       prisma.weeklyCheckInSession.findMany({
         where: { userId: uid },
@@ -33,14 +33,18 @@ export async function getWeeklyCheckInSessionsByUserId(userId: string) {
         where: { userId: uid },
         include: { session: { include: weeklyCheckInInclude } },
       }),
-    userId,
+    userId
-    (s) => resolveCollaborator(s.participant).then((r) => ({ resolvedParticipant: r }))
   );
+  const resolved = await batchResolveCollaborators(sessions.map((s) => s.participant));
+  return sessions.map((s) => ({
+    ...s,
+    resolvedParticipant: resolved.get(s.participant.trim()) ?? { raw: s.participant, matchedUser: null },
+  }));
 }
 
 /** Sessions owned by team members (where user is team admin) that are NOT shared with the user. */
 export async function getTeamCollaboratorSessionsForAdmin(userId: string) {
-  return fetchTeamCollaboratorSessions(
+  const sessions = await fetchTeamCollaboratorSessions(
     (teamMemberIds, uid) =>
       prisma.weeklyCheckInSession.findMany({
         where: { userId: { in: teamMemberIds }, shares: { none: { userId: uid } } },
@@ -48,9 +52,13 @@ export async function getTeamCollaboratorSessionsForAdmin(userId: string) {
         orderBy: { updatedAt: 'desc' },
       }),
     getTeamMemberIdsForAdminTeams,
-    userId,
+    userId
-    (s) => resolveCollaborator(s.participant).then((r) => ({ resolvedParticipant: r }))
   );
+  const resolved = await batchResolveCollaborators(sessions.map((s) => s.participant));
+  return sessions.map((s) => ({
+    ...s,
+    resolvedParticipant: resolved.get(s.participant.trim()) ?? { raw: s.participant, matchedUser: null },
+  }));
 }
 
 const weeklyCheckInByIdInclude = {

src/services/year-review.ts

@@ -1,5 +1,5 @@
 import { prisma } from '@/services/database';
-import { resolveCollaborator } from '@/services/auth';
+import { resolveCollaborator, batchResolveCollaborators } from '@/services/auth';
 import { getTeamMemberIdsForAdminTeams } from '@/services/teams';
 import { createSessionPermissionChecks } from '@/services/session-permissions';
 import { createShareAndEventHandlers } from '@/services/session-share-events';
@@ -21,7 +21,7 @@ const yearReviewInclude = {
 // ============================================
 
 export async function getYearReviewSessionsByUserId(userId: string) {
-  return mergeSessionsByUserId(
+  const sessions = await mergeSessionsByUserId(
     (uid) =>
       prisma.yearReviewSession.findMany({
         where: { userId: uid },
@@ -33,14 +33,18 @@ export async function getYearReviewSessionsByUserId(userId: string) {
         where: { userId: uid },
         include: { session: { include: yearReviewInclude } },
       }),
-    userId,
+    userId
-    (s) => resolveCollaborator(s.participant).then((r) => ({ resolvedParticipant: r }))
   );
+  const resolved = await batchResolveCollaborators(sessions.map((s) => s.participant));
+  return sessions.map((s) => ({
+    ...s,
+    resolvedParticipant: resolved.get(s.participant.trim()) ?? { raw: s.participant, matchedUser: null },
+  }));
 }
 
 /** Sessions owned by team members (where user is team admin) that are NOT shared with the user. */
 export async function getTeamCollaboratorSessionsForAdmin(userId: string) {
-  return fetchTeamCollaboratorSessions(
+  const sessions = await fetchTeamCollaboratorSessions(
     (teamMemberIds, uid) =>
       prisma.yearReviewSession.findMany({
         where: { userId: { in: teamMemberIds }, shares: { none: { userId: uid } } },
@@ -48,9 +52,13 @@ export async function getTeamCollaboratorSessionsForAdmin(userId: string) {
         orderBy: { updatedAt: 'desc' },
       }),
     getTeamMemberIdsForAdminTeams,
-    userId,
+    userId
-    (s) => resolveCollaborator(s.participant).then((r) => ({ resolvedParticipant: r }))
   );
+  const resolved = await batchResolveCollaborators(sessions.map((s) => s.participant));
+  return sessions.map((s) => ({
+    ...s,
+    resolvedParticipant: resolved.get(s.participant.trim()) ?? { raw: s.participant, matchedUser: null },
+  }));
 }
 
 const yearReviewByIdInclude = {