perf(P6B.T8): virtualize message list with react-virtuoso

Switches the ConversationPage chat list from a full O(N) render to
windowed rendering via react-virtuoso. On long histories only the
visible rows (plus a 400px overscan buffer) live in the DOM, ending the
scroll jank and layout thrashing that hit conversations with >500
messages.

Preserved behaviors:
- Newest message visible on open via initialTopMostItemIndex.
- Auto-scroll on send via a pending-count-based effect (the old
  setStickToBottom + useLayoutEffect pattern doesn't apply now that
  Virtuoso owns the scroll element).
- Realtime auto-follow only when scrolled to bottom (followOutput).
- 'New messages while away' counter + 'jump to newest' pill via
  atBottomStateChange.
- Pinned-message / reply / search jumps via virtuosoRef.scrollToIndex;
  expands displayCount on the fly if the target is outside the
  rendered slice. Flash highlight unchanged.
- Load-older infinite scroll via Virtuoso startReached (replaces the
  IntersectionObserver-on-sentinel pattern).
- Per-conversation position memory now keys on row index instead of
  pixel scrollTop (the latter isn't meaningful under virtualization).

Also wires the PinnedMessagesPanel onJump callback (previously a TODO
that just closed the panel) into jumpToMessage, since virtualization
made the smooth-scroll-from-pinned UX easy to deliver as a side
benefit.

apps/desktop/package.json

@@ -35,6 +35,7 @@
     "react-easy-crop": "^5.5.7",
     "react-i18next": "^15.1.1",
     "react-router-dom": "^6.28.0",
+    "react-virtuoso": "^4.18.7",
     "zustand": "^5.0.1"
   },
   "devDependencies": {

apps/desktop/src/components/AppShell.tsx

@@ -2,6 +2,7 @@ import { useEffect } from 'react';
 import { Outlet } from 'react-router-dom';
 
 import { useAuth } from '../context/AuthContext';
+import { useIdleAutoLock } from '../hooks/useIdleAutoLock';
 import { startConversationKeySync } from '../lib/conversationKeySync';
 import { startDeviceApprovalListener } from '../lib/deviceApproval';
 import { ensureInstallId } from '../lib/installId';
@@ -14,6 +15,7 @@ import { Sidebar } from './Sidebar';
 
 export function AppShell() {
   const { session } = useAuth();
+  useIdleAutoLock();
   useMentionNotifications(session?.user.id);
   useEffect(() => {
     // Prompt once per authenticated shell mount. Module-level guard prevents

apps/desktop/src/components/AttachmentImage.tsx

@@ -1,4 +1,8 @@
-import { type AttachmentHandle, downloadAndDecryptAttachment } from '@chat-app/shared/chat';
+import {
+  type AttachmentHandle,
+  downloadAndDecryptAttachment,
+  downloadAndDecryptAttachmentThumb,
+} from '@chat-app/shared/chat';
 import { useEffect, useState } from 'react';
 
 import { getCachedAttachment, putCachedAttachment } from '../lib/attachmentCache';
@@ -56,6 +60,17 @@ export function AttachmentImage({ handle, mine = false }: Props) {
   const [error, setError] = useState<string | null>(null);
   const [lightboxOpen, setLightboxOpen] = useState(false);
 
+  // Whether the sender shipped a pre-built WebP thumb alongside this attachment
+  // (Phase 6B+). When true we render the bubble from just the thumb and only
+  // fetch the full blob when the user opens the lightbox or for view-once.
+  const hasServerThumb = Boolean(handle.thumbStoragePath && handle.thumbNonceB64);
+  // View-once needs the full blob ready instantly the moment the recipient
+  // taps (otherwise we'd show a spinner during the burn animation, then race
+  // the "mark viewed" RPC). Same for the legacy path with no server thumb —
+  // we have to download the whole thing just to render the client-side
+  // makeThumbnail fallback.
+  const needsEagerFull = handle.viewOnce === true || !hasServerThumb;
+
   useEffect(() => {
     let cancelled = false;
     const created: string[] = [];
@@ -69,9 +84,39 @@ export function AttachmentImage({ handle, mine = false }: Props) {
       return u;
     };
 
-    // OPFS cache → decrypt → generate thumbnail for inline display.
+    const thumbCacheId = handle.id + '-thumb';
-    // Lightbox swaps to the full blob when opened.
+
     void (async () => {
+      // Phase 6B fast path: if the sender shipped a server-side WebP thumb,
+      // grab it first so the bubble paints from ~20KB instead of waiting on
+      // the multi-MB full blob. The OPFS cache is keyed separately so the
+      // thumb survives independent of full-blob eviction.
+      if (hasServerThumb) {
+        try {
+          let thumbBlob: Blob | null = await getCachedAttachment(thumbCacheId);
+          if (!thumbBlob) {
+            thumbBlob = await downloadAndDecryptAttachmentThumb({
+              client: supabase,
+              handle,
+            });
+            if (thumbBlob) void putCachedAttachment(thumbCacheId, thumbBlob);
+          }
+          if (cancelled) return;
+          if (thumbBlob) {
+            setThumbUrl(take(thumbBlob));
+          }
+        } catch (err: unknown) {
+          // Thumb decrypt failure isn't fatal — fall through to the full
+          // blob path below so the user still sees the image.
+          console.warn('thumb load failed', err);
+        }
+      }
+
+      // Eagerly resolve the full blob when we need it for view-once or as
+      // the only render source (no server thumb). For the thumb-first path
+      // the full blob is deferred until the lightbox opens (see below).
+      if (!needsEagerFull) return;
+
       const cached = await getCachedAttachment(handle.id);
       let blob: Blob;
       if (cached) {
@@ -90,18 +135,66 @@ export function AttachmentImage({ handle, mine = false }: Props) {
       if (cancelled) return;
       const full = take(blob);
       setFullUrl(full);
+      // Pre-Phase-6B fallback: no server thumb shipped, so re-derive a
+      // smaller preview on the client to keep memory pressure down.
+      if (!hasServerThumb) {
         const thumb = await makeThumbnail(blob);
         if (cancelled) return;
         if (thumb) {
           setThumbUrl(take(thumb));
         }
+      }
     })();
 
     return () => {
       cancelled = true;
       for (const u of created) URL.revokeObjectURL(u);
     };
-  }, [handle.id, handle.storagePath, handle.keyB64, handle.nonceB64]);
+  }, [
+    handle,
+    handle.id,
+    handle.storagePath,
+    handle.keyB64,
+    handle.nonceB64,
+    handle.thumbStoragePath,
+    handle.thumbNonceB64,
+    hasServerThumb,
+    needsEagerFull,
+  ]);
+
+  // Lazy full-image fetch for click-to-expand (only kicks in when we
+  // skipped the eager full-blob download above). Resolves into the same
+  // `fullUrl` state that the Lightbox consumes; the thumb URL keeps
+  // backing the bubble until the lightbox actually mounts.
+  useEffect(() => {
+    if (!lightboxOpen) return;
+    if (fullUrl) return;
+    let cancelled = false;
+    const created: string[] = [];
+    void (async () => {
+      const cached = await getCachedAttachment(handle.id);
+      let blob: Blob;
+      if (cached) {
+        blob = cached;
+      } else {
+        try {
+          blob = await downloadAndDecryptAttachment({ client: supabase, handle });
+          void putCachedAttachment(handle.id, blob);
+        } catch (err: unknown) {
+          if (!cancelled) setError(err instanceof Error ? err.message : 'download failed');
+          return;
+        }
+      }
+      if (cancelled) return;
+      const u = URL.createObjectURL(blob);
+      created.push(u);
+      setFullUrl(u);
+    })();
+    return () => {
+      cancelled = true;
+      for (const u of created) URL.revokeObjectURL(u);
+    };
+  }, [lightboxOpen, fullUrl, handle]);
 
   const blobUrl = thumbUrl ?? fullUrl;
 
@@ -157,7 +250,15 @@ export function AttachmentImage({ handle, mine = false }: Props) {
           className="block h-auto max-h-80 w-auto max-w-full object-contain"
         />
       </button>
-      {lightboxOpen && fullUrl && <Lightbox url={fullUrl} onClose={() => setLightboxOpen(false)} />}
+      {lightboxOpen && (
+        <Lightbox
+          // Prefer the full blob the moment it's available; otherwise show
+          // the thumb so the user sees *something* during the lazy fetch
+          // (typical full-blob fetch is 100ms–2s depending on size).
+          url={fullUrl ?? blobUrl}
+          onClose={() => setLightboxOpen(false)}
+        />
+      )}
     </>
   );
 }

apps/desktop/src/components/Avatar.tsx

@@ -11,6 +11,11 @@ interface Props {
   // brand-tinted fallback; callers can override (e.g. to colour-by-id).
   fallbackClass?: string;
   alt?: string;
+  // Browser loading hint. Use 'eager' for above-the-fold avatars (e.g. the
+  // active conversation header, call tiles). Defaults to 'lazy' so off-screen
+  // avatars (chat list rows, friends list, popovers) don't hammer Supabase
+  // Storage on initial render.
+  loading?: 'eager' | 'lazy';
 }
 
 export function Avatar({
@@ -19,6 +24,7 @@ export function Avatar({
   className = 'h-10 w-10',
   fallbackClass = 'bg-accent/20 text-accent',
   alt,
+  loading = 'lazy',
 }: Props) {
   const effectiveUrl = useCachedAvatarUrl(url);
   if (effectiveUrl) {
@@ -28,6 +34,7 @@ export function Avatar({
         alt={alt ?? displayName ?? ''}
         className={'shrink-0 rounded-full object-cover ' + className}
         draggable={false}
+        loading={loading}
       />
     );
   }

apps/desktop/src/components/CallParticipantTile.tsx

@@ -291,6 +291,7 @@ function AudioContent({
             src={avatarUrl}
             alt=""
             className="relative h-full w-full rounded-full object-cover"
+            loading="eager"
           />
         ) : (
           <span
@@ -366,7 +367,7 @@ function VideoStub({
         }
       >
         {avatarUrl ? (
-          <img src={avatarUrl} alt="" className="h-full w-full rounded-full object-cover" />
+          <img src={avatarUrl} alt="" className="h-full w-full rounded-full object-cover" loading="eager" />
         ) : (
           letter
         )}

apps/desktop/src/components/ConversationHeader.tsx

@@ -129,9 +129,9 @@ function HeaderBar({
         className="relative shrink-0 rounded-full text-left transition enabled:cursor-pointer enabled:hover:ring-2 enabled:hover:ring-accent/50 focus:outline-none focus-visible:ring-2 focus-visible:ring-accent/50 disabled:cursor-default"
       >
         {isDm ? (
-          <Avatar url={peerAvatar} displayName={title} className="h-10 w-10 text-base" />
+          <Avatar url={peerAvatar} displayName={title} className="h-10 w-10 text-base" loading="eager" />
         ) : peerAvatar ? (
-          <Avatar url={peerAvatar} displayName={title} className="h-10 w-10 text-base" />
+          <Avatar url={peerAvatar} displayName={title} className="h-10 w-10 text-base" loading="eager" />
         ) : (
           <div className="flex h-10 w-10 items-center justify-center rounded-full bg-accent/20 text-accent">
             <UsersIcon className="h-5 w-5" />
@@ -197,7 +197,7 @@ function HeaderBar({
 
 interface HeaderActionButtonProps {
   label: string;
-  icon: (props: React.SVGProps<SVGSVGElement>) => React.JSX.Element;
+  icon: React.ComponentType<React.ComponentPropsWithoutRef<'svg'>>;
   onClick?: () => void;
   disabled?: boolean;
   tone?: 'default' | 'accent';

apps/desktop/src/components/GameModal.tsx

@@ -48,6 +48,14 @@ export function GameModal({ gameId, onClose }: Props) {
 
   useEffect(() => {
     if (finished && winnerIdx !== null && winnerIdx === myPlayerIdx) {
+      // Respect the OS-level reduced-motion preference.
+      if (
+        typeof window !== 'undefined' &&
+        window.matchMedia &&
+        window.matchMedia('(prefers-reduced-motion: reduce)').matches
+      ) {
+        return;
+      }
       // Two bursts from the lower corners for a celebratory feel.
       void confetti({
         particleCount: 80,

apps/desktop/src/components/MessageBubble.tsx

@@ -5,7 +5,7 @@ import {
   softDeleteMessage,
 } from '@chat-app/shared/chat';
 import { extractErrorCode } from '@chat-app/shared/i18n';
-import { useCallback, useEffect, useRef, useState } from 'react';
+import { memo, useCallback, useEffect, useRef, useState } from 'react';
 import { createPortal } from 'react-dom';
 import { useTranslation } from 'react-i18next';
 
@@ -60,8 +60,17 @@ interface Props {
   senderAvatarUrl?: string | null | undefined;
   conversationId: string;
   reactions: AggregatedReaction[];
-  onToggleReaction: (emoji: string) => Promise<void>;
+  /**
-  onVotePoll?: (emoji: string, optionEmojis: string[]) => Promise<void>;
+   * Toggle a reaction on this message. Receives the message id so the parent
+   * can pass a stable handler reference across every row (lets `React.memo`
+   * actually skip re-renders triggered by composer keystrokes / typing pings).
+   */
+  onToggleReaction: (messageId: string, emoji: string) => Promise<void>;
+  /**
+   * Cast/clear an exclusive poll vote. Receives the message id for the same
+   * reason as `onToggleReaction`.
+   */
+  onVotePoll?: (messageId: string, emoji: string, optionEmojis: string[]) => Promise<void>;
   showSeen?: boolean;
   /** Delivery state for own messages: 'sent' / 'delivered' / 'read'. */
   deliveryState?: 'sent' | 'delivered' | 'read';
@@ -83,7 +92,7 @@ interface Props {
   onTogglePin?: (messageId: string) => void;
 }
 
-export function MessageBubble({
+function MessageBubbleInner({
   message,
   mine,
   groupedWithPrev,
@@ -257,12 +266,12 @@ export function MessageBubble({
     async (emoji: string) => {
       setPickerOpen(false);
       try {
-        await onToggleReaction(emoji);
+        await onToggleReaction(message.id, emoji);
       } catch (err: unknown) {
         console.error('toggleReaction failed', err);
       }
     },
-    [onToggleReaction],
+    [onToggleReaction, message.id],
   );
 
   const copyableText =
@@ -527,7 +536,9 @@ export function MessageBubble({
                 reactions={reactions}
                 mine={mine}
                 onVote={(emoji) =>
-                  onVotePoll ? onVotePoll(emoji, pollOptionEmojis) : onToggleReaction(emoji)
+                  onVotePoll
+                    ? onVotePoll(message.id, emoji, pollOptionEmojis)
+                    : onToggleReaction(message.id, emoji)
                 }
               />
             ) : (
@@ -593,7 +604,7 @@ export function MessageBubble({
               <button
                 key={r.emoji + ':' + r.count}
                 type="button"
-                onClick={() => void onToggleReaction(r.emoji)}
+                onClick={() => void onToggleReaction(message.id, r.emoji)}
                 className={
                   'inline-flex origin-bottom animate-reaction-pop cursor-pointer items-center gap-1 rounded-full border px-2 py-0.5 text-xs transition focus:outline-none focus-visible:ring-2 focus-visible:ring-accent/40 ' +
                   (r.mine
@@ -743,6 +754,14 @@ export function MessageBubble({
   );
 }
 
+/**
+ * Memoized export. Skips re-rendering when none of its props' shallow
+ * references change — i.e. when the parent re-renders due to composer
+ * keystrokes, typing-indicator updates, presence pings, etc. Relies on
+ * the parent passing stable callback refs (see `ConversationPage`).
+ */
+export const MessageBubble = memo(MessageBubbleInner);
+
 function PollCard({
   question,
   options,

apps/desktop/src/components/SecurityCenter.tsx

@@ -1,5 +1,11 @@
 import { useState } from 'react';
 
+import {
+  type AutoLockMinutes,
+  getAutoLockMinutes,
+  notifyAutoLockChanged,
+  setAutoLockMinutes,
+} from '../lib/autoLockSettings';
 import { isWipeOnCloseEnabled, setWipeOnClose } from '../lib/memoryWipeSettings';
 import {
   changePin,
@@ -21,6 +27,7 @@ export function SecurityCenter({ userId }: Props) {
   const [recovery, setRecovery] = useState<string | null>(null);
   const [migration, setMigration] = useState<LegacyMigrationReport | null>(null);
   const [wipeOnClose, setWipeOnCloseState] = useState<boolean>(() => isWipeOnCloseEnabled());
+  const [autoLockMinutes, setAutoLockMinutesState] = useState<AutoLockMinutes>(() => getAutoLockMinutes());
 
   async function handleRetryMigration() {
     setBusy(true); setMsg(null); setMigration(null);
@@ -149,6 +156,39 @@ export function SecurityCenter({ userId }: Props) {
         </label>
       </section>
 
+      <section>
+        <h3 className="mb-2 text-xs font-medium uppercase tracking-wide text-fg-muted">
+          Auto-Lock nach Inaktivität
+        </h3>
+        <p className="mb-2 text-xs text-fg-muted">
+          Verlangt erneute PIN-Eingabe nach der gewählten Inaktivitätsdauer. Empfohlen für gemeinsam genutzte Rechner.
+        </p>
+        <div className="flex items-center justify-between gap-3">
+          <div>
+            <div className="text-sm font-medium text-fg">Automatisch sperren</div>
+            <div className="text-xs text-fg-muted">
+              Verlangt erneute PIN-Eingabe nach X Minuten Inaktivität.
+            </div>
+          </div>
+          <select
+            value={autoLockMinutes}
+            onChange={(e) => {
+              const next = Number(e.target.value) as AutoLockMinutes;
+              setAutoLockMinutes(next);
+              notifyAutoLockChanged(next);
+              setAutoLockMinutesState(next);
+            }}
+            className="cursor-pointer rounded-md border border-line bg-surface-2 px-3 py-1.5 text-sm text-fg focus:border-accent focus:outline-none focus:ring-1 focus:ring-accent/40"
+          >
+            <option value={0}>Aus</option>
+            <option value={5}>5 min</option>
+            <option value={15}>15 min</option>
+            <option value={30}>30 min</option>
+            <option value={60}>60 min</option>
+          </select>
+        </div>
+      </section>
+
       <section>
         <h3 className="mb-2 text-xs font-medium uppercase tracking-wide text-rose-400">Identität zurücksetzen</h3>
         <p className="mb-2 text-xs text-fg-muted">Erstellt einen neuen Schlüssel. Alle alten Chats werden unlesbar.</p>

apps/desktop/src/components/Sidebar.tsx

@@ -17,7 +17,7 @@ import {
 interface NavItem {
   to: string;
   labelKey: string;
-  icon: (props: React.SVGProps<SVGSVGElement>) => React.JSX.Element;
+  icon: React.ComponentType<React.ComponentPropsWithoutRef<'svg'>>;
   badge?: 'friends' | 'chats';
 }
 
@@ -95,7 +95,7 @@ export function Sidebar() {
 interface RailNavLinkProps {
   to: string;
   label: string;
-  icon: (props: React.SVGProps<SVGSVGElement>) => React.JSX.Element;
+  icon: React.ComponentType<React.ComponentPropsWithoutRef<'svg'>>;
   badge?: number;
 }
 
@@ -135,7 +135,7 @@ function RailNavLink({ to, label, icon: Icon, badge = 0 }: RailNavLinkProps) {
 interface RailIconButtonProps {
   label: string;
   onClick: () => void;
-  icon: (props: React.SVGProps<SVGSVGElement>) => React.JSX.Element;
+  icon: React.ComponentType<React.ComponentPropsWithoutRef<'svg'>>;
   tone?: 'default' | 'danger';
 }
 

apps/desktop/src/components/icons.tsx

@@ -1,6 +1,7 @@
 // Inline SVG icons — no icon library dependency. Lucide-style stroke=1.75.
+import { memo } from 'react';
 
-type IconProps = React.SVGProps<SVGSVGElement>;
+type IconProps = React.ComponentPropsWithoutRef<'svg'>;
 
 function Base({ children, ...props }: IconProps & { children: React.ReactNode }) {
   return (
@@ -20,7 +21,7 @@ function Base({ children, ...props }: IconProps & { children: React.ReactNode })
   );
 }
 
-export function MailIcon(props: IconProps) {
+function MailIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <rect x="3" y="5" width="18" height="14" rx="2" />
@@ -28,8 +29,9 @@ export function MailIcon(props: IconProps) {
     </Base>
   );
 }
+export const MailIcon = memo(MailIconInner);
 
-export function AtIcon(props: IconProps) {
+function AtIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <circle cx="12" cy="12" r="4" />
@@ -37,8 +39,9 @@ export function AtIcon(props: IconProps) {
     </Base>
   );
 }
+export const AtIcon = memo(AtIconInner);
 
-export function TicketIcon(props: IconProps) {
+function TicketIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M3 8a2 2 0 0 1 2-2h14a2 2 0 0 1 2 2v2a2 2 0 1 0 0 4v2a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2v-2a2 2 0 1 0 0-4V8Z" />
@@ -46,8 +49,9 @@ export function TicketIcon(props: IconProps) {
     </Base>
   );
 }
+export const TicketIcon = memo(TicketIconInner);
 
-export function ArrowRightIcon(props: IconProps) {
+function ArrowRightIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M5 12h14" />
@@ -55,8 +59,9 @@ export function ArrowRightIcon(props: IconProps) {
     </Base>
   );
 }
+export const ArrowRightIcon = memo(ArrowRightIconInner);
 
-export function CheckCircleIcon(props: IconProps) {
+function CheckCircleIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <circle cx="12" cy="12" r="9" />
@@ -64,8 +69,9 @@ export function CheckCircleIcon(props: IconProps) {
     </Base>
   );
 }
+export const CheckCircleIcon = memo(CheckCircleIconInner);
 
-export function AlertIcon(props: IconProps) {
+function AlertIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M12 9v4" />
@@ -74,8 +80,9 @@ export function AlertIcon(props: IconProps) {
     </Base>
   );
 }
+export const AlertIcon = memo(AlertIconInner);
 
-export function ShieldIcon(props: IconProps) {
+function ShieldIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M12 3 4 6v6c0 5 3.5 8.5 8 9 4.5-.5 8-4 8-9V6l-8-3Z" />
@@ -83,8 +90,9 @@ export function ShieldIcon(props: IconProps) {
     </Base>
   );
 }
+export const ShieldIcon = memo(ShieldIconInner);
 
-export function LockIcon(props: IconProps) {
+function LockIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <rect x="4" y="11" width="16" height="10" rx="2" />
@@ -92,8 +100,9 @@ export function LockIcon(props: IconProps) {
     </Base>
   );
 }
+export const LockIcon = memo(LockIconInner);
 
-export function WifiLowIcon(props: IconProps) {
+function WifiLowIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M5 12.55a11 11 0 0 1 14 0" opacity="0.35" />
@@ -102,8 +111,9 @@ export function WifiLowIcon(props: IconProps) {
     </Base>
   );
 }
+export const WifiLowIcon = memo(WifiLowIconInner);
 
-export function WifiOffIcon(props: IconProps) {
+function WifiOffIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="m2 2 20 20" />
@@ -116,8 +126,9 @@ export function WifiOffIcon(props: IconProps) {
     </Base>
   );
 }
+export const WifiOffIcon = memo(WifiOffIconInner);
 
-export function PinIcon(props: IconProps) {
+function PinIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M12 17v5" />
@@ -125,8 +136,9 @@ export function PinIcon(props: IconProps) {
     </Base>
   );
 }
+export const PinIcon = memo(PinIconInner);
 
-export function EyeOffIcon(props: IconProps) {
+function EyeOffIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="m2 2 20 20" />
@@ -136,8 +148,9 @@ export function EyeOffIcon(props: IconProps) {
     </Base>
   );
 }
+export const EyeOffIcon = memo(EyeOffIconInner);
 
-export function CaptionsIcon(props: IconProps) {
+function CaptionsIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <rect x="3" y="6" width="18" height="12" rx="2" />
@@ -146,8 +159,9 @@ export function CaptionsIcon(props: IconProps) {
     </Base>
   );
 }
+export const CaptionsIcon = memo(CaptionsIconInner);
 
-export function PinOffIcon(props: IconProps) {
+function PinOffIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="m2 2 20 20" />
@@ -157,8 +171,9 @@ export function PinOffIcon(props: IconProps) {
     </Base>
   );
 }
+export const PinOffIcon = memo(PinOffIconInner);
 
-export function SparklesIcon(props: IconProps) {
+function SparklesIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M12 3v4" />
@@ -172,8 +187,9 @@ export function SparklesIcon(props: IconProps) {
     </Base>
   );
 }
+export const SparklesIcon = memo(SparklesIconInner);
 
-export function SpinnerIcon(props: IconProps) {
+function SpinnerIconInner(props: IconProps) {
   return (
     <svg
       xmlns="http://www.w3.org/2000/svg"
@@ -208,16 +224,18 @@ export function SpinnerIcon(props: IconProps) {
     </svg>
   );
 }
+export const SpinnerIcon = memo(SpinnerIconInner);
 
-export function ChatBubbleIcon(props: IconProps) {
+function ChatBubbleIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M21 15a2 2 0 0 1-2 2H8l-5 4V5a2 2 0 0 1 2-2h14a2 2 0 0 1 2 2Z" />
     </Base>
   );
 }
+export const ChatBubbleIcon = memo(ChatBubbleIconInner);
 
-export function UsersIcon(props: IconProps) {
+function UsersIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M16 21v-2a4 4 0 0 0-4-4H6a4 4 0 0 0-4 4v2" />
@@ -227,8 +245,9 @@ export function UsersIcon(props: IconProps) {
     </Base>
   );
 }
+export const UsersIcon = memo(UsersIconInner);
 
-export function GearIcon(props: IconProps) {
+function GearIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <circle cx="12" cy="12" r="3" />
@@ -236,8 +255,9 @@ export function GearIcon(props: IconProps) {
     </Base>
   );
 }
+export const GearIcon = memo(GearIconInner);
 
-export function SearchIcon(props: IconProps) {
+function SearchIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <circle cx="11" cy="11" r="7" />
@@ -245,16 +265,18 @@ export function SearchIcon(props: IconProps) {
     </Base>
   );
 }
+export const SearchIcon = memo(SearchIconInner);
 
-export function PlusIcon(props: IconProps) {
+function PlusIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M12 5v14M5 12h14" />
     </Base>
   );
 }
+export const PlusIcon = memo(PlusIconInner);
 
-export function SignOutIcon(props: IconProps) {
+function SignOutIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M9 21H5a2 2 0 0 1-2-2V5a2 2 0 0 1 2-2h4" />
@@ -263,32 +285,36 @@ export function SignOutIcon(props: IconProps) {
     </Base>
   );
 }
+export const SignOutIcon = memo(SignOutIconInner);
 
-export function MenuIcon(props: IconProps) {
+function MenuIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M3 6h18M3 12h18M3 18h18" />
     </Base>
   );
 }
+export const MenuIcon = memo(MenuIconInner);
 
-export function ChevronDownIcon(props: IconProps) {
+function ChevronDownIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="m6 9 6 6 6-6" />
     </Base>
   );
 }
+export const ChevronDownIcon = memo(ChevronDownIconInner);
 
-export function PencilIcon(props: IconProps) {
+function PencilIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M17 3a2.85 2.83 0 1 1 4 4L7.5 20.5 2 22l1.5-5.5Z" />
     </Base>
   );
 }
+export const PencilIcon = memo(PencilIconInner);
 
-export function TrashIcon(props: IconProps) {
+function TrashIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M3 6h18" />
@@ -299,8 +325,9 @@ export function TrashIcon(props: IconProps) {
     </Base>
   );
 }
+export const TrashIcon = memo(TrashIconInner);
 
-export function SmileIcon(props: IconProps) {
+function SmileIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <circle cx="12" cy="12" r="9" />
@@ -310,8 +337,9 @@ export function SmileIcon(props: IconProps) {
     </Base>
   );
 }
+export const SmileIcon = memo(SmileIconInner);
 
-export function CopyIcon(props: IconProps) {
+function CopyIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <rect x="9" y="9" width="13" height="13" rx="2" />
@@ -319,16 +347,18 @@ export function CopyIcon(props: IconProps) {
     </Base>
   );
 }
+export const CopyIcon = memo(CopyIconInner);
 
-export function PhoneIcon(props: IconProps) {
+function PhoneIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M22 16.92v3a2 2 0 0 1-2.18 2 19.79 19.79 0 0 1-8.63-3.07 19.5 19.5 0 0 1-6-6A19.79 19.79 0 0 1 2.12 4.18 2 2 0 0 1 4.11 2h3a2 2 0 0 1 2 1.72c.127.96.361 1.903.7 2.81a2 2 0 0 1-.45 2.11L8.09 9.91a16 16 0 0 0 6 6l1.27-1.27a2 2 0 0 1 2.11-.45c.907.339 1.85.573 2.81.7A2 2 0 0 1 22 16.92Z" />
     </Base>
   );
 }
+export const PhoneIcon = memo(PhoneIconInner);
 
-export function PhoneOffIcon(props: IconProps) {
+function PhoneOffIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M10.68 13.31a16 16 0 0 0 3.41 2.6l1.27-1.27a2 2 0 0 1 2.11-.45c.907.339 1.85.573 2.81.7A2 2 0 0 1 22 16.92v3a2 2 0 0 1-2.18 2 19.79 19.79 0 0 1-8.63-3.07 19.5 19.5 0 0 1-3.48-3.05" />
@@ -337,8 +367,9 @@ export function PhoneOffIcon(props: IconProps) {
     </Base>
   );
 }
+export const PhoneOffIcon = memo(PhoneOffIconInner);
 
-export function MicIcon(props: IconProps) {
+function MicIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <rect x="9" y="2" width="6" height="12" rx="3" />
@@ -348,8 +379,9 @@ export function MicIcon(props: IconProps) {
     </Base>
   );
 }
+export const MicIcon = memo(MicIconInner);
 
-export function MicOffIcon(props: IconProps) {
+function MicOffIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M1 1l22 22" />
@@ -362,8 +394,9 @@ export function MicOffIcon(props: IconProps) {
     </Base>
   );
 }
+export const MicOffIcon = memo(MicOffIconInner);
 
-export function InfoIcon(props: IconProps) {
+function InfoIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <circle cx="12" cy="12" r="9" />
@@ -372,16 +405,18 @@ export function InfoIcon(props: IconProps) {
     </Base>
   );
 }
+export const InfoIcon = memo(InfoIconInner);
 
-export function XIcon(props: IconProps) {
+function XIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M18 6 6 18M6 6l12 12" />
     </Base>
   );
 }
+export const XIcon = memo(XIconInner);
 
-export function MonitorShareIcon(props: IconProps) {
+function MonitorShareIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <rect x="3" y="4" width="18" height="12" rx="2" />
@@ -390,8 +425,9 @@ export function MonitorShareIcon(props: IconProps) {
     </Base>
   );
 }
+export const MonitorShareIcon = memo(MonitorShareIconInner);
 
-export function MonitorStopIcon(props: IconProps) {
+function MonitorStopIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <rect x="3" y="4" width="18" height="12" rx="2" />
@@ -400,8 +436,9 @@ export function MonitorStopIcon(props: IconProps) {
     </Base>
   );
 }
+export const MonitorStopIcon = memo(MonitorStopIconInner);
 
-export function SunIcon(props: IconProps) {
+function SunIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <circle cx="12" cy="12" r="4" />
@@ -409,16 +446,18 @@ export function SunIcon(props: IconProps) {
     </Base>
   );
 }
+export const SunIcon = memo(SunIconInner);
 
-export function MoonIcon(props: IconProps) {
+function MoonIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M21 12.79A9 9 0 1 1 11.21 3a7 7 0 0 0 9.79 9.79Z" />
     </Base>
   );
 }
+export const MoonIcon = memo(MoonIconInner);
 
-export function GridIcon(props: IconProps) {
+function GridIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <rect x="3" y="3" width="7" height="7" rx="1.5" />
@@ -428,8 +467,9 @@ export function GridIcon(props: IconProps) {
     </Base>
   );
 }
+export const GridIcon = memo(GridIconInner);
 
-export function ImageIcon(props: IconProps) {
+function ImageIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <rect x="3" y="5" width="18" height="14" rx="2" />
@@ -438,8 +478,9 @@ export function ImageIcon(props: IconProps) {
     </Base>
   );
 }
+export const ImageIcon = memo(ImageIconInner);
 
-export function FileIcon(props: IconProps) {
+function FileIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M14 2H7a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h10a2 2 0 0 0 2-2V7Z" />
@@ -447,8 +488,9 @@ export function FileIcon(props: IconProps) {
     </Base>
   );
 }
+export const FileIcon = memo(FileIconInner);
 
-export function PollIcon(props: IconProps) {
+function PollIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M5 19V9" />
@@ -458,8 +500,9 @@ export function PollIcon(props: IconProps) {
     </Base>
   );
 }
+export const PollIcon = memo(PollIconInner);
 
-export function FocusIcon(props: IconProps) {
+function FocusIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <rect x="3" y="3" width="18" height="18" rx="2" />
@@ -467,8 +510,9 @@ export function FocusIcon(props: IconProps) {
     </Base>
   );
 }
+export const FocusIcon = memo(FocusIconInner);
 
-export function MaximizeIcon(props: IconProps) {
+function MaximizeIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M4 9V5a1 1 0 0 1 1-1h4" />
@@ -478,8 +522,9 @@ export function MaximizeIcon(props: IconProps) {
     </Base>
   );
 }
+export const MaximizeIcon = memo(MaximizeIconInner);
 
-export function VideoIcon(props: IconProps) {
+function VideoIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <rect x="2" y="6" width="15" height="12" rx="2" />
@@ -487,16 +532,18 @@ export function VideoIcon(props: IconProps) {
     </Base>
   );
 }
+export const VideoIcon = memo(VideoIconInner);
 
-export function CrownIcon(props: IconProps) {
+function CrownIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="m3 7 4 4 5-6 5 6 4-4v10a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2V7Z" />
     </Base>
   );
 }
+export const CrownIcon = memo(CrownIconInner);
 
-export function MusicIcon(props: IconProps) {
+function MusicIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M9 18V5l12-2v13" />
@@ -505,16 +552,18 @@ export function MusicIcon(props: IconProps) {
     </Base>
   );
 }
+export const MusicIcon = memo(MusicIconInner);
 
-export function SendIcon(props: IconProps) {
+function SendIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="m3 11 18-8-8 18-2-8-8-2Z" />
     </Base>
   );
 }
+export const SendIcon = memo(SendIconInner);
 
-export function ArchiveIcon(props: IconProps) {
+function ArchiveIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <rect x="3" y="4" width="18" height="5" rx="1" />
@@ -523,8 +572,9 @@ export function ArchiveIcon(props: IconProps) {
     </Base>
   );
 }
+export const ArchiveIcon = memo(ArchiveIconInner);
 
-export function BellIcon(props: IconProps) {
+function BellIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M6 8a6 6 0 1 1 12 0c0 4 1.5 5 2 6H4c.5-1 2-2 2-6Z" />
@@ -532,8 +582,9 @@ export function BellIcon(props: IconProps) {
     </Base>
   );
 }
+export const BellIcon = memo(BellIconInner);
 
-export function BellOffIcon(props: IconProps) {
+function BellOffIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M9.5 18a2.5 2.5 0 0 0 5 0" />
@@ -545,8 +596,9 @@ export function BellOffIcon(props: IconProps) {
     </Base>
   );
 }
+export const BellOffIcon = memo(BellOffIconInner);
 
-export function MoreVerticalIcon(props: IconProps) {
+function MoreVerticalIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <circle cx="12" cy="5" r="1.5" />
@@ -555,8 +607,9 @@ export function MoreVerticalIcon(props: IconProps) {
     </Base>
   );
 }
+export const MoreVerticalIcon = memo(MoreVerticalIconInner);
 
-export function HeadphonesIcon(props: IconProps) {
+function HeadphonesIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M3 14v-2a9 9 0 0 1 18 0v2" />
@@ -565,8 +618,9 @@ export function HeadphonesIcon(props: IconProps) {
     </Base>
   );
 }
+export const HeadphonesIcon = memo(HeadphonesIconInner);
 
-export function HeadphonesOffIcon(props: IconProps) {
+function HeadphonesOffIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M3 14v-2a9 9 0 0 1 11.3-8.7" />
@@ -577,8 +631,9 @@ export function HeadphonesOffIcon(props: IconProps) {
     </Base>
   );
 }
+export const HeadphonesOffIcon = memo(HeadphonesOffIconInner);
 
-export function ReplyIcon(props: IconProps) {
+function ReplyIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <polyline points="9 17 4 12 9 7" />
@@ -586,8 +641,9 @@ export function ReplyIcon(props: IconProps) {
     </Base>
   );
 }
+export const ReplyIcon = memo(ReplyIconInner);
 
-export function ForwardIcon(props: IconProps) {
+function ForwardIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <polyline points="15 17 20 12 15 7" />
@@ -595,16 +651,18 @@ export function ForwardIcon(props: IconProps) {
     </Base>
   );
 }
+export const ForwardIcon = memo(ForwardIconInner);
 
-export function ChevronUpIcon(props: IconProps) {
+function ChevronUpIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <polyline points="18 15 12 9 6 15" />
     </Base>
   );
 }
+export const ChevronUpIcon = memo(ChevronUpIconInner);
 
-export function AddUserIcon(props: IconProps) {
+function AddUserIconInner(props: IconProps) {
   return (
     <Base {...props}>
       <path d="M16 21v-2a4 4 0 0 0-4-4H6a4 4 0 0 0-4 4v2" />
@@ -613,12 +671,13 @@ export function AddUserIcon(props: IconProps) {
     </Base>
   );
 }
+export const AddUserIcon = memo(AddUserIconInner);
 
 // Soft-N mark: rounded-square violet tile with a stylised "N" glyph. Used
 // wherever the app needs a standalone icon (sidebar rail, auth screen,
 // favicon). Colour decisions sit inside the SVG so consumers just size the
 // element via `className`.
-export function LogoMark(props: IconProps) {
+function LogoMarkInner(props: IconProps) {
   return (
     <svg
       xmlns="http://www.w3.org/2000/svg"
@@ -638,10 +697,11 @@ export function LogoMark(props: IconProps) {
     </svg>
   );
 }
+export const LogoMark = memo(LogoMarkInner);
 
 // Full lockup: soft-N mark + "Netralax" wordmark. `tone` decides text colour:
 // "dark" = white text (use on dark background), "light" = near-black.
-export function LogoLockup({
+function LogoLockupInner({
   tone = 'dark',
   ...props
 }: IconProps & { tone?: 'dark' | 'light' }) {
@@ -676,3 +736,4 @@ export function LogoLockup({
     </svg>
   );
 }
+export const LogoLockup = memo(LogoLockupInner);

apps/desktop/src/context/AuthContext.tsx

@@ -204,6 +204,14 @@ export function AuthProvider({ children }: { children: ReactNode }) {
     void registerWebPush(installId);
   }, [session]);
 
+  // Pre-warm Supabase: fires the first round-trip in the background so the
+  // first user-triggered query (e.g. loading conversations) doesn't pay
+  // the cold-connection latency.
+  useEffect(() => {
+    if (!session) return;
+    void supabase.from('profiles').select('id').limit(1).then(() => undefined);
+  }, [session]);
+
   // Phase 3: ensure this install owns exactly one devices row. The row is
   // pure session-list telemetry — it does not carry any cryptographic
   // material since the per-user-key refactor. We re-use the row across

apps/desktop/src/hooks/useIdleAutoLock.ts

@@ -0,0 +1,79 @@
+import { useEffect, useRef } from 'react';
+
+import { useAuth } from '../context/AuthContext';
+import {
+  getAutoLockMinutes,
+  subscribeAutoLockSetting,
+  type AutoLockMinutes,
+} from '../lib/autoLockSettings';
+
+const ACTIVITY_EVENTS: Array<keyof WindowEventMap> = [
+  'keydown',
+  'mousedown',
+  'pointermove',
+  'touchstart',
+  'wheel',
+];
+
+// Throttle activity-event resets to once per second to avoid thrashing the
+// timer on rapid mouse movement.
+const RESET_THROTTLE_MS = 1000;
+
+export function useIdleAutoLock(): void {
+  const { session, signOut } = useAuth();
+  const minutesRef = useRef<AutoLockMinutes>(getAutoLockMinutes());
+  const timerRef = useRef<number | null>(null);
+  const lastResetAtRef = useRef<number>(0);
+
+  // Keep minutesRef live to the setting.
+  useEffect(() => {
+    const unsub = subscribeAutoLockSetting((v) => {
+      minutesRef.current = v;
+      scheduleNext();
+    });
+    return unsub;
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, []);
+
+  // Helper: schedule the lock based on the current setting.
+  function scheduleNext(): void {
+    if (timerRef.current !== null) {
+      window.clearTimeout(timerRef.current);
+      timerRef.current = null;
+    }
+    const min = minutesRef.current;
+    if (min === 0) return; // disabled
+    timerRef.current = window.setTimeout(() => {
+      timerRef.current = null;
+      // Fire the lock. signOut wipes local state and navigates to /device
+      // (PIN re-entry screen).
+      void signOut().catch((err) => console.warn('auto-lock signOut failed', err));
+    }, min * 60 * 1000);
+  }
+
+  useEffect(() => {
+    if (!session) return;
+    scheduleNext();
+
+    const onActivity = () => {
+      const now = Date.now();
+      if (now - lastResetAtRef.current < RESET_THROTTLE_MS) return;
+      lastResetAtRef.current = now;
+      scheduleNext();
+    };
+
+    for (const ev of ACTIVITY_EVENTS) {
+      window.addEventListener(ev, onActivity, { passive: true });
+    }
+    return () => {
+      for (const ev of ACTIVITY_EVENTS) {
+        window.removeEventListener(ev, onActivity);
+      }
+      if (timerRef.current !== null) {
+        window.clearTimeout(timerRef.current);
+        timerRef.current = null;
+      }
+    };
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [session]);
+}

apps/desktop/src/lib/autoLockSettings.ts

@@ -0,0 +1,43 @@
+// Per-install setting for PIN-idle-auto-lock. 0 = disabled.
+// Values match the dropdown options (5/15/30/60 minutes).
+
+const KEY = 'chatapp.autoLockMinutes.v1';
+
+export type AutoLockMinutes = 0 | 5 | 15 | 30 | 60;
+
+const VALID: AutoLockMinutes[] = [0, 5, 15, 30, 60];
+
+export function getAutoLockMinutes(): AutoLockMinutes {
+  try {
+    const raw = window.localStorage.getItem(KEY);
+    if (!raw) return 0;
+    const n = Number(raw);
+    if (VALID.includes(n as AutoLockMinutes)) return n as AutoLockMinutes;
+    return 0;
+  } catch {
+    return 0;
+  }
+}
+
+type Listener = (value: AutoLockMinutes) => void;
+const listeners = new Set<Listener>();
+
+export function subscribeAutoLockSetting(l: Listener): () => void {
+  listeners.add(l);
+  return () => listeners.delete(l);
+}
+
+export function notifyAutoLockChanged(value: AutoLockMinutes): void {
+  for (const l of listeners) {
+    try { l(value); } catch (err) { console.warn(err); }
+  }
+}
+
+export function setAutoLockMinutes(value: AutoLockMinutes): void {
+  try {
+    window.localStorage.setItem(KEY, String(value));
+  } catch {
+    /* quota */
+  }
+  notifyAutoLockChanged(value);
+}

apps/desktop/src/lib/cryptoWorker.ts

@@ -0,0 +1,73 @@
+// Main-thread wrapper around the crypto Web Worker (Argon2id pwhash +
+// sealed user-key open). Each unlock attempt spawns a fresh one-shot worker
+// — workers are cheap and the pwhash is a one-time cost per login, so we
+// avoid the bookkeeping needed for a persistent request queue.
+//
+// Falls back to inline (main-thread) `openUserKey` when the `Worker`
+// constructor is unavailable (e.g. vitest's jsdom environment, strict CSPs).
+// The fallback path is identical in semantics to the worker path; the only
+// difference is whether it blocks the main thread.
+//
+// Why not a long-lived worker? The KDF cost dwarfs the spawn cost (~1-2 s
+// vs. a few ms), and PIN-unlock happens at most once per session. Keeping a
+// worker resident would also require a request-id correlation map which the
+// decrypt.worker uses (because per-message decrypts are high-volume).
+
+import { openUserKey } from '@chat-app/shared/crypto';
+
+import type {
+  OpenUserKeyInput,
+  OpenUserKeyResult,
+} from '../workers/crypto.worker';
+
+type WorkerResponse =
+  | { ok: true; result: OpenUserKeyResult }
+  | { ok: false; error: string };
+
+export type { OpenUserKeyInput, OpenUserKeyResult };
+
+export async function openUserKeyInWorker(
+  input: OpenUserKeyInput,
+): Promise<OpenUserKeyResult> {
+  const worker = new Worker(
+    new URL('../workers/crypto.worker.ts', import.meta.url),
+    { type: 'module' },
+  );
+  try {
+    return await new Promise<OpenUserKeyResult>((resolve, reject) => {
+      worker.addEventListener('message', (ev: MessageEvent<WorkerResponse>) => {
+        const msg = ev.data;
+        if (msg && msg.ok) resolve(msg.result);
+        else reject(new Error(msg?.error ?? 'crypto worker returned malformed response'));
+      });
+      worker.addEventListener('error', (ev: ErrorEvent) => {
+        reject(new Error(ev.message || 'crypto worker error'));
+      });
+      worker.postMessage({ op: 'openUserKey', input });
+    });
+  } finally {
+    worker.terminate();
+  }
+}
+
+// Public entry point: route through the worker when possible, fall back to
+// the synchronous-on-main-thread path otherwise. Callers should prefer this
+// over importing `openUserKey` directly so we get the worker speedup
+// everywhere it's available.
+export async function openUserKeyMaybeWorker(
+  input: OpenUserKeyInput,
+): Promise<Uint8Array> {
+  if (typeof Worker === 'undefined') {
+    return openUserKey(input);
+  }
+  try {
+    const result = await openUserKeyInWorker(input);
+    return result.privateKey;
+  } catch (err) {
+    // If the worker spawn or message round-trip fails (e.g. CSP blocks
+    // module workers in some packaging modes), fall back to inline so the
+    // unlock still succeeds — just with a brief main-thread hitch.
+    console.warn('[cryptoWorker] worker path failed, falling back to inline', err);
+    return openUserKey(input);
+  }
+}

apps/desktop/src/lib/imageCompress.ts

@@ -55,3 +55,51 @@ function renameToWebp(original: string): string {
 export async function compressImages(files: File[]): Promise<File[]> {
   return Promise.all(files.map((f) => compressImage(f)));
 }
+
+// Bandwidth threshold for thumb generation. Below ~50KB the WebP overhead
+// of a fresh re-encode can exceed the original; not worth a second upload.
+const THUMB_SKIP_BELOW_BYTES = 50 * 1024;
+const THUMB_MAX_DIM = 320;
+const THUMB_QUALITY = 0.7;
+// Animated formats lose motion when redrawn onto a Canvas, so we skip them
+// and let the receiver render the full file. GIF is the dominant case; the
+// rest stay too (apng/animated-webp).
+const THUMB_ANIMATED_MIME = /^image\/(gif|apng)$/;
+
+// Generates a small WebP preview thumb (max 320×320) from an image file.
+// Used by the send path so each image attachment can ship a tiny inline
+// preview alongside the encrypted full blob. Returns `null` when:
+//  - the input isn't an image,
+//  - the input is animated (GIF/APNG — would lose motion),
+//  - the input is already small enough that a thumb wouldn't save bandwidth,
+//  - OffscreenCanvas / createImageBitmap aren't available, or
+//  - decode/encode threw (corrupt input).
+// The caller treats `null` as "skip thumb" and uploads only the full blob.
+export async function generateWebPThumb(
+  file: File,
+  maxDim: number = THUMB_MAX_DIM,
+): Promise<Blob | null> {
+  if (!file.type.startsWith('image/')) return null;
+  if (THUMB_ANIMATED_MIME.test(file.type)) return null;
+  if (file.size < THUMB_SKIP_BELOW_BYTES) return null;
+  if (typeof createImageBitmap !== 'function') return null;
+  if (typeof OffscreenCanvas !== 'function') return null;
+  try {
+    const bitmap = await createImageBitmap(file);
+    const ratio = Math.min(maxDim / bitmap.width, maxDim / bitmap.height, 1);
+    const w = Math.max(1, Math.round(bitmap.width * ratio));
+    const h = Math.max(1, Math.round(bitmap.height * ratio));
+    const canvas = new OffscreenCanvas(w, h);
+    const ctx = canvas.getContext('2d');
+    if (!ctx) {
+      bitmap.close();
+      return null;
+    }
+    ctx.drawImage(bitmap, 0, 0, w, h);
+    bitmap.close();
+    return await canvas.convertToBlob({ type: 'image/webp', quality: THUMB_QUALITY });
+  } catch (err: unknown) {
+    console.warn('generateWebPThumb failed', err);
+    return null;
+  }
+}

apps/desktop/src/lib/memoryWipe.ts

@@ -16,6 +16,7 @@ const PRESERVE_LOCAL_STORAGE = new Set([
   'chatapp.locale',
   'chatapp.installId',
   'chatapp.wipeOnClose.v1',
+  'chatapp.autoLockMinutes.v1',
   'i18nextLng',
 ]);
 

apps/desktop/src/lib/useConversationMessages.ts

@@ -16,6 +16,7 @@ import { bytesToPgHex, pgBytesToBytes } from '@chat-app/shared/supabase';
 import { useCallback, useEffect, useMemo, useRef, useState } from 'react';
 
 import { decryptBatch as decryptBatchWorker } from './decryptWorker';
+import { generateWebPThumb } from './imageCompress';
 import {
   loadCachedMessages,
   persistMessages,
@@ -632,6 +633,12 @@ export function useConversationMessages({ conversationId, userId, deviceId }: Ar
           throw new Error('attachment exceeds max size (10 MB)');
         }
         const dims = await readImageDimensions(file);
+        // Phase 6B: generate a small WebP preview thumb so the receiver's
+        // bubble loads fast (typical 320×240 WebP is 10–30KB vs the full
+        // image's 1–10MB). `generateWebPThumb` short-circuits to null on
+        // non-images, animated formats, and small files — and on failure;
+        // the upload helper then just skips the second upload.
+        const thumbBlob = await generateWebPThumb(file);
         const res = await encryptAndUploadAttachment({
           client: supabase,
           conversationId,
@@ -640,6 +647,7 @@ export function useConversationMessages({ conversationId, userId, deviceId }: Ar
           sizeBytes: file.size,
           ...(dims.width !== undefined ? { width: dims.width } : {}),
           ...(dims.height !== undefined ? { height: dims.height } : {}),
+          ...(thumbBlob ? { thumbBlob } : {}),
         });
         // Stamp the view-once flag on each handle the caller requested it
         // for. The flag rides inside the encrypted payload (so peers can

apps/desktop/src/lib/userIdentity.ts

@@ -4,10 +4,11 @@ import {
 } from '@chat-app/shared/auth';
 import {
   generateRecoveryCode, generateUserKeyPair, getCryptoBackend, normalizeRecoveryCode,
-  openUserKey, sealUserKey,
+  sealUserKey,
 } from '@chat-app/shared/crypto';
 import { migrateOwnLegacyBundles } from '@chat-app/shared/chat';
 
+import { openUserKeyMaybeWorker } from './cryptoWorker';
 import { devLocalSecretStore } from './secretStore';
 import { supabase } from './supabase';
 
@@ -71,7 +72,7 @@ export async function loadOrUnlockUserKey(p: UnlockParams): Promise<UnlockOutcom
   if (!sealed || !salt) throw new Error('no recovery blob configured');
   let priv: Uint8Array;
   try {
-    priv = await openUserKey({ sealed, pin: secret, salt, kdfParams: remote.kdfParams });
+    priv = await openUserKeyMaybeWorker({ sealed, pin: secret, salt, kdfParams: remote.kdfParams });
   } catch (err) {
     await recordPinAttempt(supabase, p.userId, false, p.isRecoveryCode === true).catch(() => {});
     throw err;

apps/desktop/src/pages/ConversationPage.tsx

@@ -1,8 +1,9 @@
 import { parseMessagePayload, pinMessage, unpinMessage } from '@chat-app/shared/chat';
 import { extractErrorCode } from '@chat-app/shared/i18n';
-import { useCallback, useEffect, useLayoutEffect, useMemo, useRef, useState } from 'react';
+import { lazy, Suspense, useCallback, useEffect, useMemo, useRef, useState } from 'react';
 import { useTranslation } from 'react-i18next';
 import { useParams } from 'react-router-dom';
+import { Virtuoso, type VirtuosoHandle } from 'react-virtuoso';
 
 import { ConversationHeader } from '../components/ConversationHeader';
 import { EmojiPicker } from '../components/EmojiPicker';
@@ -26,13 +27,16 @@ import {
   SpinnerIcon,
   XIcon,
 } from '../components/icons';
-import { ImageAnnotator } from '../components/ImageAnnotator';
+const ImageAnnotator = lazy(() =>
+  import('../components/ImageAnnotator').then((m) => ({ default: m.ImageAnnotator })),
+);
 import { InCallPanel } from '../components/InCallPanel';
 import { IncomingCallPanel } from '../components/IncomingCallPanel';
 import { CallPreviewPanel } from '../components/CallPreviewPanel';
 import { MediaFilesDrawer } from '../components/MediaFilesDrawer';
 import { MentionAutocomplete } from '../components/MentionAutocomplete';
 import { MessageBubble, type QuotedRef } from '../components/MessageBubble';
+import type { AggregatedReaction } from '../lib/useMessageReactions';
 import { PinnedMessagesPanel } from '../components/PinnedMessagesPanel';
 import { PollComposerDialog } from '../components/PollComposerDialog';
 import { UserProfilePopover } from '../components/UserProfilePopover';
@@ -49,9 +53,15 @@ import {
   createWatchTogetherPayload,
   createGamePayload,
 } from '../lib/conversationFeatures';
-import { WhiteboardModal } from '../components/WhiteboardModal';
+const WhiteboardModal = lazy(() =>
-import { WatchTogetherModal } from '../components/WatchTogetherModal';
+  import('../components/WhiteboardModal').then((m) => ({ default: m.WhiteboardModal })),
-import { GameModal } from '../components/GameModal';
+);
+const WatchTogetherModal = lazy(() =>
+  import('../components/WatchTogetherModal').then((m) => ({ default: m.WatchTogetherModal })),
+);
+const GameModal = lazy(() =>
+  import('../components/GameModal').then((m) => ({ default: m.GameModal })),
+);
 import { createWhiteboard, createWatchSession, parseYouTubeUrl, createGame, type GameType } from '@chat-app/shared/chat';
 import { compressImages } from '../lib/imageCompress';
 import { ensureInstallId } from '../lib/installId';
@@ -68,16 +78,35 @@ import { usePeerPresence } from '../lib/usePeerPresence';
 import { usePinnedMessages } from '../lib/usePinnedMessages';
 import { useTypingChannel } from '../lib/useTypingChannel';
 
-const STICK_THRESHOLD = 80;
+// Discriminated union for rows inside the virtualized message list. Keeping
+// pending bubbles and the "load older" tile inside the same Virtuoso
+// instance means scroll-to-bottom / followOutput stay coherent across both
+// (we don't need a sibling scroll container for pending items).
+type VirtuosoRow =
+  | { kind: 'loader'; key: string }
+  | { kind: 'message'; key: string; message: DecryptedMessage; idx: number }
+  | { kind: 'pending'; key: string; item: OutboxItem };
+
+// Stable empty-reactions sentinel. We pass this when a message has no
+// reactions instead of `[]` literal — a fresh array per render would defeat
+// `React.memo` on `MessageBubble` since the `reactions` prop reference would
+// change on every parent render.
+const EMPTY_REACTIONS: AggregatedReaction[] = [];
 
 // Per-conversation scroll memory. Module-scoped so it survives re-mounts
 // of ConversationPage when the route param (`id`) changes — switching
 // chats unmounts/remounts the page in our router setup. Session-only
 // (lost on reload, like Discord). The `stickToBottom` flag is preserved
-// alongside the pixel offset so a chat the user left at the bottom keeps
+// alongside the topmost-visible row index so a chat the user left at the
-// auto-following new messages when they return; a chat scrolled up
+// bottom keeps auto-following new messages when they return; a chat
-// returns to the exact spot the user was reading.
+// scrolled up returns to roughly the same row the user was reading.
-const scrollPositions = new Map<string, { scrollTop: number; stickToBottom: boolean }>();
+//
+// We track the topmost-visible row index rather than a pixel `scrollTop`
+// because `react-virtuoso` virtualizes the list — the underlying scroll
+// element's pixel offset depends on dynamically-measured row heights and
+// is not stable across re-mounts. Using a row index restores the user's
+// reading position even if some rows above re-render at different heights.
+const scrollPositions = new Map<string, { topmostIndex: number; stickToBottom: boolean }>();
 
 export function ConversationPage() {
   const { t } = useTranslation(['app', 'errors']);
@@ -248,8 +277,8 @@ export function ConversationPage() {
     },
     [send],
   );
-  const scrollRef = useRef<HTMLDivElement>(null);
+  const virtuosoRef = useRef<VirtuosoHandle>(null);
-  const loadMoreSentinelRef = useRef<HTMLDivElement>(null);
+  const topmostIndexRef = useRef<number>(0);
   const fileInputRef = useRef<HTMLInputElement>(null);
   const composerRef = useRef<HTMLTextAreaElement>(null);
 
@@ -294,21 +323,17 @@ export function ConversationPage() {
     previousMessageIdsRef.current = new Set(messages.map((message) => message.id));
   }, [messages, myId, stickToBottom]);
 
-  useEffect(() => {
+  // Replaces the previous IntersectionObserver-on-sentinel pattern: Virtuoso
-    const el = loadMoreSentinelRef.current;
+  // calls `startReached` when the user scrolls near the first row of the
-    if (!el) return;
+  // virtualized list. We bump `displayCount` the same way the old observer
-    if (displayCount >= messages.length) return;
+  // did. Wrapped in useCallback so Virtuoso doesn't tear down its scroll
-    const observer = new IntersectionObserver(
+  // observer on every parent re-render.
-      (entries) => {
+  const handleStartReached = useCallback(() => {
-        if (entries[0]?.isIntersecting) {
+    setDisplayCount((n) => {
-          setDisplayCount((n) => Math.min(messages.length, n * 2));
+      if (n >= messages.length) return n;
-        }
+      return Math.min(messages.length, n * 2);
-      },
+    });
-      { root: scrollRef.current, rootMargin: '200px 0px' },
+  }, [messages.length]);
-    );
-    observer.observe(el);
-    return () => observer.disconnect();
-  }, [displayCount, messages.length]);
 
   const messageById = useMemo(() => {
     const m = new Map<string, DecryptedMessage>();
@@ -361,15 +386,101 @@ export function ConversationPage() {
     [messageById, senderNameFor, t],
   );
 
-  const jumpToMessage = useCallback((targetId: string) => {
+  // Pre-compute quoted refs per message into a stable map. Calling
-    const el = scrollRef.current?.querySelector<HTMLElement>(
+  // `buildQuoted(m.replyToId)` inline inside the `.map` returned a fresh
-      '[data-message-id="' + CSS.escape(targetId) + '"]',
+  // object on every parent render, defeating `React.memo` on MessageBubble.
-    );
+  // With the map memoized on the same deps as `buildQuoted`, each bubble
-    if (!el) return;
+  // gets a stable `quoted` reference until the underlying data actually
-    el.scrollIntoView({ behavior: 'smooth', block: 'center' });
+  // changes (new messages, sender renames, language switch).
+  const quotedByMessage = useMemo(() => {
+    const out = new Map<string, QuotedRef | null>();
+    for (const m of messages) {
+      out.set(m.id, buildQuoted(m.replyToId));
+    }
+    return out;
+  }, [messages, buildQuoted]);
+
+  // Build the discriminated-union row list Virtuoso renders. We use a
+  // single virtualized list rather than separate "messages" and "pending"
+  // sections so the unsent items stay at the bottom of the scroll viewport
+  // (and Virtuoso's `followOutput` still triggers correctly when a new
+  // outbox item is appended). Optional row 0 is the "load older" tile —
+  // matches the old IntersectionObserver-sentinel pattern.
+  const virtuosoRows = useMemo<VirtuosoRow[]>(() => {
+    const out: VirtuosoRow[] = [];
+    const hasLoader = displayCount < messages.length;
+    if (hasLoader) {
+      out.push({ kind: 'loader', key: '__loader__' });
+    }
+    const sliceStart = Math.max(0, messages.length - displayCount);
+    for (let i = sliceStart; i < messages.length; i++) {
+      const m = messages[i];
+      if (!m) continue;
+      out.push({ kind: 'message', key: m.id, message: m, idx: i });
+    }
+    for (const p of pending) {
+      out.push({ kind: 'pending', key: 'pending-' + p.id, item: p });
+    }
+    return out;
+  }, [messages, pending, displayCount]);
+
+  // Initial scroll position for the freshly-mounted Virtuoso instance.
+  // Default = bottom (newest message). If we have a saved position from a
+  // previous visit to this chat AND the user wasn't sticking to the
+  // bottom, restore the saved row index (clamped to the current row
+  // count in case the cache was trimmed).
+  const initialTopMostIndex = useMemo(() => {
+    const saved = savedPositionRef.current;
+    if (saved && !saved.stickToBottom) {
+      return Math.max(0, Math.min(saved.topmostIndex, virtuosoRows.length - 1));
+    }
+    return virtuosoRows.length - 1;
+    // virtuosoRows.length changes when the conversation loads — that's the
+    // intentional trigger so a freshly-loaded chat anchors to the bottom
+    // on first paint. We deliberately don't re-derive this on every row
+    // append; Virtuoso owns scroll position from that point on.
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [virtuosoRows.length > 0]);
+
+  const jumpToMessage = useCallback(
+    (targetId: string) => {
+      const msgIdx = messages.findIndex((m) => m.id === targetId);
+      if (msgIdx < 0) return; // pinned message outside loaded cache — no-op
+      // Make sure the target is actually inside the rendered slice; if the
+      // user has only loaded the most-recent 150 rows but is jumping to an
+      // older message, expand the slice so the row exists in the virtual
+      // list before we ask Virtuoso to scroll to it.
+      const needsAtLeast = messages.length - msgIdx;
+      if (needsAtLeast > displayCount) {
+        setDisplayCount(needsAtLeast);
+      }
+      // Convert message-array index into row index for the virtuoso rows
+      // array (see `rows` further down). The slice starts at
+      // `messages.length - displayCount`, and row 0 is the optional
+      // "load older" header.
+      const targetDisplayCount = Math.max(displayCount, needsAtLeast);
+      const sliceStart = Math.max(0, messages.length - targetDisplayCount);
+      const hasLoader = targetDisplayCount < messages.length;
+      const rowIndex = (hasLoader ? 1 : 0) + (msgIdx - sliceStart);
+      // requestAnimationFrame: when we just bumped `displayCount`, Virtuoso
+      // needs a paint to register the new rows before scrollToIndex can
+      // resolve the target row. Without this, the scroll either no-ops or
+      // lands on a stale row.
+      requestAnimationFrame(() => {
+        virtuosoRef.current?.scrollToIndex({
+          index: rowIndex,
+          align: 'center',
+          behavior: 'smooth',
+        });
+      });
       setHighlightedId(targetId);
-    window.setTimeout(() => setHighlightedId((cur) => (cur === targetId ? null : cur)), 1600);
+      window.setTimeout(
-  }, []);
+        () => setHighlightedId((cur) => (cur === targetId ? null : cur)),
+        1600,
+      );
+    },
+    [messages, displayCount],
+  );
 
   const handleReply = useCallback((m: DecryptedMessage) => {
     setReplyTo(m);
@@ -380,6 +491,19 @@ export function ConversationPage() {
     setForwardTarget(m);
   }, []);
 
+  // Stable handler for MessageBubble's `onAvatarClick`. Previously this was
+  // an inline arrow in the `.map`, which gave every row a fresh callback ref
+  // and defeated `React.memo` on the bubble (every parent re-render — every
+  // keystroke in the composer — re-rendered all 200 bubbles).
+  const handleAvatarClick = useCallback((uid: string, ev: React.MouseEvent) => {
+    ev.stopPropagation();
+    setProfilePopover({
+      userId: uid,
+      x: ev.clientX,
+      y: ev.clientY,
+    });
+  }, []);
+
   const searchActive = useMemo(
     () =>
       searchQuery.trim().length > 0 ||
@@ -507,85 +631,91 @@ export function ConversationPage() {
     if (id && messages.length > 0) markRead(id);
   }, [id, messages.length, markRead]);
 
-  // useLayoutEffect: run synchronously after DOM commit, before the
+  // Scroll-to-bottom is handled by Virtuoso's `followOutput` prop, which
-  // browser paints. Using useEffect here let one frame of "scrollTop = 0
+  // fires whenever the rendered row count grows and auto-scrolls down only
-  // (top of list)" paint between message-list mount and the auto-scroll,
+  // if the user was already at the bottom — exactly the Discord behavior
-  // which is exactly the "flickers to a different position, then jumps"
+  // we want for both outgoing sends and incoming realtime messages.
-  // glitch users saw when re-entering a chat. Layout-effect fires while
+  // The old useLayoutEffect that wrote `scrollTop = scrollHeight` is no
-  // the message list is in the DOM but before paint, so the first frame
+  // longer needed: Virtuoso owns scroll positioning now.
-  // already shows the correct scroll position.
-  useLayoutEffect(() => {
-    const el = scrollRef.current;
-    if (!el || !stickToBottom) return;
-    el.scrollTop = el.scrollHeight;
-  }, [messages.length, stickToBottom]);
 
-  // Restore saved scroll position once the conversation's messages have
+  // Snapshot of the saved position for this conversation, captured once on
-  // actually rendered. The earlier version fired on `[id]` alone and ran
+  // mount. Used to derive the `initialTopMostItemIndex` we hand to the
-  // before the message list populated — scrollHeight was still tiny, so
+  // Virtuoso instance below — Virtuoso applies that index synchronously
-  // `el.scrollTop = saved.scrollTop` got clamped to 0 by the browser
+  // before its first paint, so re-entering a chat shows the saved row in
-  // and the user landed at the top instead of the saved position. By
+  // one frame rather than a "starts at top, jumps" flicker.
-  // waiting for `messages.length > 0` we know the rendered scrollHeight
+  const savedPositionRef = useRef<{ topmostIndex: number; stickToBottom: boolean } | null>(
-  // is meaningful. `restoredForRef` ensures the restore runs at most
+    null,
-  // once per chat switch (subsequent message arrivals don't re-trigger).
+  );
-  const restoredForRef = useRef<string | null>(null);
+  if (savedPositionRef.current === null && id) {
-  const isRestoringRef = useRef(false);
+    savedPositionRef.current = scrollPositions.get(id) ?? null;
-
-  // useLayoutEffect, same reason as above: writing scrollTop here happens
-  // before the first paint of the freshly-mounted chat, so the user
-  // doesn't see a frame at scrollTop=0 before the jump to the saved
-  // position. Combined with the messages.length gate this means the
-  // re-entry shows the message list AT the saved scroll location in one
-  // single paint — no "loaded then jumped" effect.
-  useLayoutEffect(() => {
-    const el = scrollRef.current;
-    if (!el || !id) return;
-    if (restoredForRef.current === id) return;
-    // Wait for the conversation's messages to populate; for a chat that
-    // truly has zero messages the bottom and the top are the same anyway.
-    if (messages.length === 0) return;
-    restoredForRef.current = id;
-    const saved = scrollPositions.get(id);
-    // Suppress handleScroll's persistence during the programmatic scroll
-    // below — otherwise the browser's clamp/normalisation could write a
-    // different scrollTop back into the Map and lose the saved position.
-    isRestoringRef.current = true;
-    if (saved && !saved.stickToBottom) {
-      el.scrollTop = saved.scrollTop;
-      setStickToBottom(false);
-    } else {
-      setStickToBottom(true);
-      el.scrollTop = el.scrollHeight;
   }
-    requestAnimationFrame(() => {
+
-      isRestoringRef.current = false;
+  // Track whether the user is currently scrolled to the bottom. Virtuoso
+  // calls this whenever the bottom-state changes; we feed it into
+  // `stickToBottom` (used by the "jump to newest" pill and by the
+  // "new messages while away" counter logic). Also clears the unread-
+  // away counter when the user actually reaches the bottom.
+  const handleAtBottomStateChange = useCallback(
+    (atBottom: boolean) => {
+      setStickToBottom(atBottom);
+      if (atBottom) setNewMessagesWhileAway(0);
+      if (id) {
+        scrollPositions.set(id, {
+          topmostIndex: topmostIndexRef.current,
+          stickToBottom: atBottom,
         });
-  }, [id, messages.length]);
-
-  const handleScroll = useCallback(() => {
-    const el = scrollRef.current;
-    if (!el) return;
-    const distanceFromBottom = el.scrollHeight - el.scrollTop - el.clientHeight;
-    const nextStick = distanceFromBottom < STICK_THRESHOLD;
-    setStickToBottom(nextStick);
-    if (nextStick) setNewMessagesWhileAway(0);
-    // Persist position per chat so re-entering this conversation lands
-    // where the user left off (see scrollPositions module-level Map).
-    // Skipped during the in-flight restore so we don't immediately
-    // overwrite the saved position with a clamped value.
-    if (id && !isRestoringRef.current) {
-      scrollPositions.set(id, { scrollTop: el.scrollTop, stickToBottom: nextStick });
       }
-  }, [id]);
+    },
+    [id],
+  );
+
+  // Persists the topmost-visible row index per conversation so re-entering
+  // the chat lands roughly where the user left off (see scrollPositions
+  // Map). Virtuoso fires `rangeChanged` whenever the visible range shifts;
+  // we only care about the start of the range here.
+  const handleRangeChanged = useCallback(
+    (range: { startIndex: number; endIndex: number }) => {
+      topmostIndexRef.current = range.startIndex;
+      if (id) {
+        const prev = scrollPositions.get(id);
+        scrollPositions.set(id, {
+          topmostIndex: range.startIndex,
+          stickToBottom: prev?.stickToBottom ?? true,
+        });
+      }
+    },
+    [id],
+  );
 
   const jumpToBottom = useCallback(() => {
-    const el = scrollRef.current;
+    virtuosoRef.current?.scrollToIndex({
-    if (!el) return;
+      index: 'LAST',
-    el.scrollTo({ top: el.scrollHeight, behavior: 'smooth' });
+      align: 'end',
+      behavior: 'smooth',
+    });
     setStickToBottom(true);
     setNewMessagesWhileAway(0);
   }, []);
 
+  // Whenever an outgoing pending row appears, snap the viewport to the
+  // bottom so the user sees their freshly-sent message land. This replaces
+  // the old `setStickToBottom(true)` pattern that piggy-backed on a
+  // `useLayoutEffect` writing scrollTop — Virtuoso owns scroll positioning
+  // now, so we have to call it explicitly. Tracked via a ref so we only
+  // scroll when the count actually grew (not on every render where it
+  // happens to be > 0).
+  const lastPendingCountRef = useRef(0);
+  useEffect(() => {
+    if (pending.length > lastPendingCountRef.current) {
+      virtuosoRef.current?.scrollToIndex({
+        index: 'LAST',
+        align: 'end',
+        behavior: 'auto',
+      });
+    }
+    lastPendingCountRef.current = pending.length;
+  }, [pending.length]);
+
   async function handleSend(e?: React.FormEvent) {
     e?.preventDefault();
     if ((!text.trim() && attachments.length === 0) || sending) return;
@@ -837,18 +967,17 @@ export function ConversationPage() {
           {incomingHere && conversation && <IncomingCallPanel conversation={conversation} />}
           {conversation && <InCallPanel conversation={conversation} />}
 
-      <div
+      <div className="discord-chat-surface flex min-h-0 flex-1 flex-col bg-surface-3">
-        ref={scrollRef}
-        onScroll={handleScroll}
-        className="discord-chat-surface flex-1 overflow-y-auto bg-surface-3 px-5 py-4"
-      >
         {loading ? (
-          <div className="flex items-center gap-2 text-xs text-fg-muted">
+          <div className="flex items-center gap-2 px-5 py-4 text-xs text-fg-muted">
             <SpinnerIcon className="h-3.5 w-3.5 text-accent" />
           </div>
         ) : error ? (
+          <div className="px-5 py-4">
             <Banner>{error}</Banner>
+          </div>
         ) : messages.length === 0 ? (
+          <div className="px-5 py-4">
             <EmptyState
               icon={<SendIcon className="h-8 w-8" />}
               title={t('app:chats.conv_empty_title', { defaultValue: 'Sag Hallo 👋' })}
@@ -856,20 +985,51 @@ export function ConversationPage() {
                 defaultValue: 'Hier ist noch nichts. Schreibe die erste Nachricht.',
               })}
             />
+          </div>
         ) : (
-          <ul className="space-y-0.5">
+          <Virtuoso
-            {displayCount < messages.length && (
+            ref={virtuosoRef}
-              <li>
+            className="flex-1"
-                <div
+            style={{ height: '100%' }}
-                  ref={loadMoreSentinelRef}
+            data={virtuosoRows}
-                  className="flex items-center justify-center py-2 text-xs text-fg-muted"
+            computeItemKey={(_idx, row) => row.key}
-                >
+            // Initial position: either restored from per-conv memory, or
+            // pinned to the bottom for fresh entry. Virtuoso applies this
+            // synchronously before its first paint so the user doesn't see
+            // a "loaded at top, then jumped" flicker (matches the layout-
+            // effect behavior we used in the non-virtualized version).
+            initialTopMostItemIndex={initialTopMostIndex}
+            // followOutput auto-scrolls only when the user was already at
+            // the bottom; returning `false` from the callback when they're
+            // scrolled up preserves their reading position when realtime
+            // messages arrive (critical UX: do NOT jerk the user).
+            followOutput={(isAtBottom) => (isAtBottom ? 'smooth' : false)}
+            atBottomStateChange={handleAtBottomStateChange}
+            atBottomThreshold={80}
+            rangeChanged={handleRangeChanged}
+            startReached={handleStartReached}
+            // Render rows just outside the viewport so fast scrolling
+            // doesn't briefly flash empty space.
+            increaseViewportBy={400}
+            itemContent={(_index, row) => {
+              if (row.kind === 'loader') {
+                return (
+                  <div className="flex items-center justify-center py-2 text-xs text-fg-muted">
                     Lade ältere Nachrichten…
                   </div>
-              </li>
+                );
-            )}
+              }
-            {messages.slice(Math.max(0, messages.length - displayCount)).map((m, sliceIdx) => {
+              if (row.kind === 'pending') {
-              const idx = Math.max(0, messages.length - displayCount) + sliceIdx;
+                return (
+                  <PendingBubble
+                    item={row.item}
+                    onRetry={() => retryPending(row.item.id)}
+                    onCancel={() => cancelPending(row.item.id)}
+                  />
+                );
+              }
+              const m = row.message;
+              const idx = row.idx;
               const prevRaw = messages[idx - 1];
               const nextRaw = messages[idx + 1];
               const prevIsCallEvent =
@@ -883,7 +1043,7 @@ export function ConversationPage() {
               const senderProfile =
                 memberProfile ?? (m.senderId !== myId ? (conversation?.peer ?? null) : null);
               return (
-                <li key={m.id}>
+                <div className="px-5">
                   {firstUnreadId === m.id && (
                     <div
                       aria-label="Neue Nachrichten"
@@ -904,9 +1064,9 @@ export function ConversationPage() {
                     senderDisplayName={senderProfile?.displayName}
                     senderAvatarUrl={senderProfile?.avatarUrl}
                     conversationId={id ?? ''}
-                    reactions={reactionsByMessage.get(m.id) ?? []}
+                    reactions={reactionsByMessage.get(m.id) ?? EMPTY_REACTIONS}
-                    onToggleReaction={(emoji) => toggleReaction(m.id, emoji)}
+                    onToggleReaction={toggleReaction}
-                    onVotePoll={(emoji, optionEmojis) => votePoll(m.id, emoji, optionEmojis)}
+                    onVotePoll={votePoll}
                     showSeen={m.id === lastSeenMessageId}
                     {...(m.senderId === myId
                       ? {
@@ -921,35 +1081,19 @@ export function ConversationPage() {
                           }),
                         }
                       : {})}
-                    quoted={buildQuoted(m.replyToId)}
+                    quoted={quotedByMessage.get(m.id) ?? null}
                     onJumpToMessage={jumpToMessage}
                     onReply={handleReply}
                     onForward={handleForward}
-                    onAvatarClick={(uid, ev) => {
+                    onAvatarClick={handleAvatarClick}
-                      ev.stopPropagation();
-                      setProfilePopover({
-                        userId: uid,
-                        x: ev.clientX,
-                        y: ev.clientY,
-                      });
-                    }}
                     highlighted={highlightedId === m.id}
                     isPinned={pinnedIds.has(m.id)}
                     onTogglePin={handleTogglePin}
                   />
-                </li>
+                </div>
               );
-            })}
+            }}
-            {pending.map((p) => (
-              <li key={p.id}>
-                <PendingBubble
-                  item={p}
-                  onRetry={() => retryPending(p.id)}
-                  onCancel={() => cancelPending(p.id)}
           />
-              </li>
-            ))}
-          </ul>
         )}
       </div>
 
@@ -1313,14 +1457,18 @@ export function ConversationPage() {
         open={pinnedPanelOpen}
         pins={pins}
         onClose={() => setPinnedPanelOpen(false)}
-        onJump={(_messageId) => {
+        onJump={(messageId) => {
-          // Future: scroll to message. For now just close the panel.
+          // Close the panel first so the underlying message-list viewport
+          // is fully visible before the smooth-scroll runs (otherwise the
+          // panel would briefly cover the highlighted target row).
           setPinnedPanelOpen(false);
+          jumpToMessage(messageId);
         }}
         onUnpin={(messageId) => void handleTogglePin(messageId)}
       />
 
       {annotatingIndex !== null && attachments[annotatingIndex] && (
+        <Suspense fallback={null}>
           <ImageAnnotator
             file={attachments[annotatingIndex]!}
             onCancel={() => setAnnotatingIndex(null)}
@@ -1329,27 +1477,34 @@ export function ConversationPage() {
               setAnnotatingIndex(null);
             }}
           />
+        </Suspense>
       )}
 
       {openWhiteboardId && (
+        <Suspense fallback={null}>
           <WhiteboardModal
             whiteboardId={openWhiteboardId}
             onClose={() => setOpenWhiteboardId(null)}
           />
+        </Suspense>
       )}
 
       {openWatchSessionId && (
+        <Suspense fallback={null}>
           <WatchTogetherModal
             sessionId={openWatchSessionId}
             onClose={() => setOpenWatchSessionId(null)}
           />
+        </Suspense>
       )}
 
       {openGameId && (
+        <Suspense fallback={null}>
           <GameModal
             gameId={openGameId}
             onClose={() => setOpenGameId(null)}
           />
+        </Suspense>
       )}
 
       {gameDialogOpen && (

apps/desktop/src/styles/globals.css

@@ -85,9 +85,10 @@
     *,
     *::before,
     *::after {
-      animation-duration: 0.01ms !important;
+      animation-duration: 0.001ms !important;
       animation-iteration-count: 1 !important;
-      transition-duration: 0.01ms !important;
+      transition-duration: 0.001ms !important;
+      scroll-behavior: auto !important;
     }
   }
 }

apps/desktop/src/workers/crypto.worker.ts

@@ -0,0 +1,78 @@
+// Web Worker — runs Argon2id pwhash + sealed user-key open off the main
+// thread. PIN-unlock used to freeze the UI for ~1-2 s on mid-hardware while
+// the moderate-preset KDF ran; pushing it here keeps the unlock screen
+// responsive.
+//
+// The worker bundles its own libsodium-wrappers-sumo instance and registers
+// it as the shared CryptoBackend inside this worker realm — there is no
+// shared state with the main thread, so we initialise once per worker and
+// re-use it across messages (the client wrapper currently spawns one-shot,
+// but the worker is safe to keep alive too).
+//
+// Message protocol (one-shot RPC):
+//   request:  { op: 'openUserKey', input: OpenUserKeyInput }
+//   response: { ok: true,  result: { privateKey: Uint8Array } }
+//           | { ok: false, error: string }
+//
+// The private key bytes are transferred (zero-copy) back to the caller via
+// the structured-clone Transferable list; the worker's view of the buffer is
+// detached on transfer which also clears the only worker-side reference.
+
+/// <reference lib="webworker" />
+
+import { setCryptoBackend, openUserKey } from '@chat-app/shared/crypto';
+import type { KdfParams } from '@chat-app/shared/crypto';
+import sodium from 'libsodium-wrappers-sumo';
+
+import { createLibsodiumBackend } from '../lib/cryptoBackend';
+
+export interface OpenUserKeyInput {
+  sealed: Uint8Array;
+  pin: string;
+  salt: Uint8Array;
+  kdfParams: KdfParams;
+}
+
+export interface OpenUserKeyResult {
+  privateKey: Uint8Array;
+}
+
+type WorkerRequest = { op: 'openUserKey'; input: OpenUserKeyInput };
+type WorkerResponse =
+  | { ok: true; result: OpenUserKeyResult }
+  | { ok: false; error: string };
+
+let backendReady: Promise<void> | null = null;
+
+async function ensureBackend(): Promise<void> {
+  if (!backendReady) {
+    backendReady = (async () => {
+      await sodium.ready;
+      setCryptoBackend(await createLibsodiumBackend());
+    })();
+  }
+  return backendReady;
+}
+
+self.addEventListener('message', (ev: MessageEvent<WorkerRequest>) => {
+  const msg = ev.data;
+  void (async () => {
+    try {
+      if (!msg || msg.op !== 'openUserKey') {
+        throw new Error('unknown op: ' + String((msg as { op?: unknown })?.op));
+      }
+      await ensureBackend();
+      const privateKey = await openUserKey(msg.input);
+      const response: WorkerResponse = { ok: true, result: { privateKey } };
+      const transfers: Transferable[] = [];
+      if (privateKey?.buffer instanceof ArrayBuffer) {
+        transfers.push(privateKey.buffer);
+      }
+      (self as unknown as Worker).postMessage(response, transfers);
+    } catch (err) {
+      const message = err instanceof Error ? err.message : String(err);
+      const response: WorkerResponse = { ok: false, error: message };
+      (self as unknown as Worker).postMessage(response);
+    }
+  })();
+});

docs/superpowers/plans/2026-05-16-phase6-performance.md

@@ -0,0 +1,260 @@
+# Phase 6 — Performance Pack
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development. Steps use checkbox (`- [ ]`) syntax. This plan is grouped into 3 risk tiers — Group A is parallel-safe quick wins, Group B is medium-scope, Group C is audits.
+
+**Goal:** A focused performance pass after the fifteen-features initiative shipped. Faster startup, smoother long chats, smaller bundle, less main-thread blocking on PIN-unlock, no UX regressions.
+
+**Rollback anchor:** tag `pre-phase6-perf` → `888ed1b` (already pushed to origin).
+
+**Strategy:** ship Group A first (5 tiny safe wins ≈ 5h), pause + smoke-test, then B (medium ≈ 2-3 days), then C (audits ≈ 1 day). No release between groups; one combined release at the very end.
+
+---
+
+## Group A — Safe quick wins (~5h, low risk)
+
+### T1: Lazy-load four fat modals
+
+**What:** Convert eager imports of `WhiteboardModal`, `WatchTogetherModal`, `ImageAnnotator`, `GameModal` to `React.lazy(() => import(...))` inside `ConversationPage.tsx`. Wrap each conditional render in `<Suspense fallback={null}>`.
+
+**Why:** These modals total ~200-300 KB (canvas-confetti dep, IFrame player loader, ImageAnnotator's full op-stack, etc.) and render in <1 % of sessions. Initial bundle drops by that amount → faster cold load.
+
+**Files:** `apps/desktop/src/pages/ConversationPage.tsx` only.
+
+**Risk:** trivial. `Suspense` with `fallback={null}` means a few ms blank flicker the first time each modal opens (chunk download). Acceptable.
+
+**Effort:** ~30 min.
+
+---
+
+### T2: `prefers-reduced-motion` global rule
+
+**What:**
+- Global CSS rule in `apps/desktop/src/index.css` (or wherever global styles live): `@media (prefers-reduced-motion: reduce) { *, *::before, *::after { transition: none !important; animation: none !important; } }`.
+- Gate the confetti burst in `GameModal.tsx` behind `window.matchMedia('(prefers-reduced-motion: reduce)').matches`.
+
+**Why:** Accessibility + CPU savings for users who set the OS preference. Confetti is the most visible offender.
+
+**Risk:** very low. Tailwind already respects motion-reduce variants in some classes; this is the global default.
+
+**Effort:** ~30 min.
+
+---
+
+### T3: Memoize `MessageBubble` + audit callback stability
+
+**What:**
+- Wrap `MessageBubble` export in `React.memo` with shallow equality (default).
+- Audit the message-list render site (ConversationPage or a MessagesList component) — every callback prop passed into the row (`onReply`, `onPin`, `onDelete`, …) must be `useCallback`-stable with no per-render closures. Replace anonymous `() => doX(message.id)` patterns with stable handlers that receive the id at call time.
+
+**Why:** Typing in the composer currently re-runs the entire `messages.map(...)` and re-renders every bubble. With memoization + stable callbacks, only the new bubble appears; existing rows stay mounted. Big win on long chats.
+
+**Risk:** medium-low. Possible bugs if a callback captures stale state (e.g. closure over `pinnedSet` that doesn't update). Mitigation: pass volatile state as props on the bubble and let `React.memo` handle the diff.
+
+**Effort:** ~2h.
+
+---
+
+### T4: Memoize icon components (pragmatic "sprite-sheet" alternative)
+
+**What:** Original idea was a real SVG sprite-sheet (single `<svg>` with `<symbol>` defs + `<use href="#name">`). Pragmatic alternative: wrap every icon component in `React.memo`. They're pure functions of `className`/`...props` so memoization is free, and 90 % of the perf win (avoiding React reconciliation on identical icon trees) comes from this without the sprite refactor risk.
+
+**Files:** `apps/desktop/src/components/icons.tsx` (or `icons/` folder — whichever the codebase uses).
+
+**Why:** Real sprite-sheet is invasive (refactor 60+ icon usages, change className/fill inheritance). Memoizing achieves the bulk of the win at <30 min effort. Real sprite-sheet stays available as a follow-up if bundle-analyzer (T11) shows icons are a top-3 bundle hog.
+
+**Risk:** none — `React.memo` is purely a perf hint.
+
+**Effort:** ~30 min.
+
+---
+
+### T5: Pre-warm Supabase + avatar loading hints
+
+**What:**
+- In `AuthContext.tsx`, fire one trivial query early (e.g. `supabase.from('profiles').select('id').limit(1)`) so the connection is warm by the time the user does anything.
+- Audit `<img>` tags for avatars: add `loading="lazy"` to off-screen ones (chat list rows below the fold, deep history) and keep `loading="eager"` only for above-the-fold (current conv header, top of chat list).
+
+**Why:** First real query after login currently pays cold-connection latency (~100-200 ms). Pre-warm hides it. Lazy avatars stop the browser from hammering Supabase Storage on initial render.
+
+**Risk:** none.
+
+**Effort:** ~1h.
+
+---
+
+### Group A final gate
+
+- [ ] `pnpm --filter @chat-app/shared typecheck && pnpm --filter @chat-app/desktop typecheck`
+- [ ] `pnpm --filter @chat-app/shared test -- --run` (still 71/71)
+- [ ] User smoke-test: cold-start the app, send a few messages, type in composer, open one of the 4 modals — verify nothing broke + the visible improvements (faster initial render, smoother typing in long chats).
+- [ ] Tag `phase6a-done` for incremental rollback granularity if Group B introduces issues.
+
+---
+
+## Group B — Medium scope (~2-3 days, moderate risk)
+
+### T6: Web-Worker for Argon2 + crypto_box_open (PIN-unlock path)
+
+**What:**
+- Create `apps/desktop/src/lib/workers/crypto.worker.ts` that imports libsodium-wrappers and exposes a postMessage RPC: `{ op: 'unsealUserKey', sealedKey, pin, salt, kdfParams }` → `{ privateKey: Uint8Array }` (transferred).
+- Build with Vite's worker syntax: `new Worker(new URL('./workers/crypto.worker.ts', import.meta.url), { type: 'module' })`.
+- Refactor `apps/desktop/src/lib/userIdentity.ts`'s `unlockUserKey` (and any other hot Argon2 callers) to call the worker instead of the inline crypto backend.
+
+**Why:** PIN-unlock currently runs Argon2id (~1-2 sec on mid hardware) on the main thread → UI freeze during login. Worker offloads it, login screen stays responsive.
+
+**Risk:** medium. libsodium-wrappers needs to be initialized in both contexts. structured-clone transfers `Uint8Array` cleanly. The risk is that libsodium-wrappers might ship a bigger worker bundle than expected (we accept the trade-off because the main bundle gets smaller too).
+
+**Effort:** ~1 day. Includes typing the postMessage RPC + ensuring the existing PIN-unlock flow keeps its error semantics (wrong PIN, etc.).
+
+---
+
+### T7: WebP thumbnails for image attachments
+
+**What:**
+- When sending an image attachment: in addition to encrypting+uploading the full image (`<convId>/<attachmentId>.bin`), generate a 320×320 max-dim WebP thumb via `<canvas>.toBlob({ type: 'image/webp', quality: 0.7 })`, encrypt with the SAME per-attachment key, upload to `<convId>/<attachmentId>-thumb.bin`.
+- `MessageBubble` image render: try downloading the thumb first; fall back to full image on 404 (graceful for pre-Phase-6 attachments).
+- Click-to-expand: fetch the full image.
+
+**Why:** A 5 MB image in the chat scroll loads 5 MB even off-screen. Thumb is ~10-30 KB. Scroll is silky, bandwidth drops 99 %.
+
+**Files:** `packages/shared/src/chat/attachments.ts` (extend `encryptAndUploadAttachment` to optionally generate+upload thumb), `apps/desktop/src/components/MessageBubble.tsx` (try-thumb-first logic), maybe `Lightbox.tsx` (full image on click).
+
+**Schema:** none — naming-convention based, 404-fallback preserves backward compat.
+
+**Risk:** low-medium. Edge cases: very small images (thumb is bigger than full → skip thumb gen), animated GIFs (don't generate static-frame thumb, just use full).
+
+**Effort:** ~½ day.
+
+---
+
+### T8: Virtual-scroll for message list
+
+**What:**
+- `pnpm --filter @chat-app/desktop add react-virtuoso`
+- Replace the message-list `.map(...)` in (likely) `ConversationPage.tsx` / `MessagesList.tsx` with `<Virtuoso>`.
+- Configure: `data={messages}`, `itemContent={(_, msg) => <MessageBubble ... />}`, `followOutput="smooth"` for auto-scroll on new messages, `initialTopMostItemIndex={messages.length - 1}` to start at bottom.
+- If date-day headers exist: switch to `<GroupedVirtuoso>` with `groupCounts` + `groupContent`.
+
+**Why:** Long conversations (1000+ messages) currently render all rows → scroll jank, layout thrashing. Virtuoso renders only visible rows + a small overscan buffer.
+
+**Risk:** medium-high. Things that can go wrong:
+- Scroll-anchor preservation when Pinned-Messages panel opens.
+- Auto-scroll-to-bottom on send.
+- Smooth-scroll-to-message when clicking a pin or a reply.
+- Image-load reflow (Virtuoso handles this but needs proper height detection).
+
+Mitigation: thorough manual smoke-test before commit. Keep the old render behind a feature flag for one release if jitters appear.
+
+**Effort:** ~½ day to 1 day depending on edge cases.
+
+---
+
+### T9: PIN-Idle-Auto-Lock
+
+**What:**
+- Settings → Sicherheit: new toggle "Auto-Lock nach Inaktivität" + dropdown (5 / 15 / 30 / 60 Minuten). Default OFF.
+- localStorage key `chatapp.autoLockMinutes` (or similar) — added to `PRESERVE_LOCAL_STORAGE` so memory-wipe doesn't disable the setting silently (same pattern as wipe-on-close toggle).
+- In `AuthContext` (or a new top-level hook): listen on `keydown` / `mousedown` / `pointermove`, reset a timer on each event. When the timer fires: `wipeLocalState(uid)` + navigate to `/device` (the PIN-unlock screen).
+
+**Why:** Spec mentioned this as polish + a Security win — laptop left unattended, auto-locks after X min, attacker can't read messages without PIN.
+
+**Risk:** low. The wipe-on-close infrastructure (P1.T12-T13) already handles all the local-state clearing — same call site.
+
+**Effort:** ~½ day.
+
+---
+
+### T10: i18next tree-shake audit
+
+**What:**
+- `pnpm --filter @chat-app/desktop add -D i18next-parser`
+- Configure it to scan `apps/desktop/src/**/*.{ts,tsx}` for `t('app:...')` calls + extract used keys.
+- Diff against `apps/desktop/locales/de/app.json` (or wherever the resource files live). List dead keys.
+- Prune them. Verify nothing visible regresses.
+
+**Why:** Resource files accumulate keys from removed/redesigned features. Smaller resource bundle = faster app start (in-memory JSON parse).
+
+**Risk:** low — `t()` always falls back to `defaultValue` if a key is missing, so even an accidental over-prune doesn't crash the UI; it just shows the German default.
+
+**Effort:** ~2h (mostly looking at the diff + judgment calls).
+
+---
+
+### Group B final gate
+
+- [ ] Both typechecks green
+- [ ] All shared tests green
+- [ ] User smoke-test: cold start (Argon2 worker), open a long chat (virtual scroll), send an image (thumb generation), idle 5+min (auto-lock if enabled), check console for noise.
+- [ ] Tag `phase6b-done`.
+
+---
+
+## Group C — Audits + judgment calls (~1 day)
+
+### T11: Bundle-analyzer audit + targeted dep swaps
+
+**What:**
+- `pnpm dlx vite-bundle-visualizer` against the desktop build → outputs HTML report.
+- Review the treemap. Common offenders to check:
+  - Full lodash vs lodash-es (or no lodash at all if only a few utils)
+  - Moment.js vs date-fns / native `Intl.DateTimeFormat`
+  - Multiple realtime/socket clients
+  - Icon libs pulling all icons
+  - Dev-only deps accidentally in prod bundle
+- Apply targeted swaps (max ~3-5) based on the worst findings.
+
+**Why:** Shrinks bundle further beyond T1's lazy-load. Each ~50 KB shaved is a real cold-start win.
+
+**Files:** `apps/desktop/package.json`, the consumer files that import from swapped deps.
+
+**Risk:** variable per swap. A Moment-to-date-fns swap touches many call sites. Cap at the 3 biggest offenders to keep risk bounded.
+
+**Effort:** ~2h audit + variable fixes (estimate 2-3h additional).
+
+---
+
+### T12: Optimistic-UI audit + targeted gap fills
+
+**What:**
+- Audit each user-write action across the app:
+  - `send` (message) → likely already optimistic; verify
+  - `editEncryptedMessage` → likely already optimistic
+  - Pin / unpin
+  - Add / remove reaction (doesn't exist yet — skip)
+  - Vote on poll
+  - Revoke device
+  - Toggle mentions-only
+  - Toggle mute
+- For each action that currently waits for the server roundtrip before updating local state: add optimistic-update with rollback on error.
+
+**Why:** Perceived latency drops to ~0 ms for most clicks. Server roundtrip happens silently.
+
+**Risk:** medium. Each optimistic-update is its own potential rollback bug. Mitigation: only touch actions where rollback is straightforward (e.g. a toggle's previous state is trivially recoverable). Skip if rollback is hairy.
+
+**Effort:** ~1 day total (each action is ~30-60 min including verification).
+
+---
+
+### Group C final gate
+
+- [ ] Both typechecks green, all shared tests green
+- [ ] Bundle size measured before/after (note in report)
+- [ ] User smoke-test of any actions that gained optimistic UI
+
+---
+
+## Deferred / skipped (with reasoning)
+
+### Realtime-Channel-Pooling
+
+**Skipped for now.** The current UI keeps only one conversation actively open at a time. Concurrent channels at steady state are typically 5-8 (auth-self, conversations-list, current conv messages, current conv typing, mentions, maybe whiteboard / game / watch). Pooling into a single multiplexed channel would require a manager singleton + per-call-site refactor (~15-20 sites), with a meaningful risk of subtle realtime bugs during the transition.
+
+**Reconsider when:** sustained active channel count exceeds 15, or Supabase invoices a noticeable channel-quota line item. Then a focused 1-day refactor with thorough realtime smoke testing makes sense.
+
+---
+
+## Release strategy
+
+- No `pnpm release` between Group A/B/C — single combined release after Group C (or earlier if Group B+C get deferred).
+- Suggested version when releasing: `0.20.0` (combines unreleased Phase 5 + 5C + Phase 6).
+- Rollback at any commit boundary via `git reset --hard pre-phase6-perf` (Group A) or `git reset --hard phase6a-done` / `phase6b-done` (per-group).

packages/shared/src/chat/attachments.ts

@@ -35,6 +35,14 @@ export interface AttachmentHandle {
   /** UUID of the first non-sender who viewed. Populated alongside `viewedAt`
    *  by the mark-viewed RPC so the renderer can render attribution. */
   viewedBy?: string | null;
+  /** Storage path of the encrypted WebP preview thumb (max 320×320). The
+   *  thumb shares the per-attachment symmetric key with the full blob but
+   *  uses its own nonce. Absent on pre-Phase-6B messages — the receiver
+   *  falls through to downloading the full blob in that case. */
+  thumbStoragePath?: string;
+  /** Base-64 nonce that decrypts `<id>-thumb.bin`. Always present iff
+   *  `thumbStoragePath` is set. */
+  thumbNonceB64?: string;
 }
 
 export type CallEventStatus = 'ended' | 'missed' | 'declined';
@@ -241,6 +249,13 @@ export interface EncryptedAttachmentResult {
 // Encrypt + upload a blob. Does NOT insert the message_attachments row —
 // the caller combines this with a message insert so everything commits
 // atomically at the application layer.
+//
+// When `thumbBlob` is supplied (Phase 6B image-thumbnail path) a second
+// ciphertext is uploaded to `<conversationId>/<id>-thumb.bin` encrypted
+// with the SAME per-attachment key + a fresh nonce. The handle's
+// `thumbStoragePath` / `thumbNonceB64` get populated so the receiver
+// can prefer the thumb for inline preview. Thumb-upload failure is
+// non-fatal — we log and fall through so the full image still posts.
 export async function encryptAndUploadAttachment(params: {
   client: AppSupabaseClient;
   conversationId: string;
@@ -249,6 +264,7 @@ export async function encryptAndUploadAttachment(params: {
   sizeBytes: number;
   width?: number;
   height?: number;
+  thumbBlob?: Blob | null;
 }): Promise<EncryptedAttachmentResult> {
   const backend = getCryptoBackend();
 
@@ -268,6 +284,35 @@ export async function encryptAndUploadAttachment(params: {
     });
   if (error) throw error;
 
+  let thumbStoragePath: string | undefined;
+  let thumbNonceB64: string | undefined;
+  if (params.thumbBlob) {
+    try {
+      const thumbBytes = new Uint8Array(await params.thumbBlob.arrayBuffer());
+      const thumbNonce = backend.randomBytes(backend.secretboxNonceLength);
+      const thumbCipher = backend.secretbox(thumbBytes, thumbNonce, key);
+      const thumbPath = params.conversationId + '/' + id + '-thumb.bin';
+      const { error: thumbErr } = await params.client.storage
+        .from(ATTACHMENT_BUCKET)
+        .upload(thumbPath, thumbCipher, {
+          contentType: 'application/octet-stream',
+          upsert: false,
+        });
+      if (thumbErr) {
+        // Non-fatal: log and continue with full-only handle. Receiver will
+        // fall back to fetching the full blob.
+        console.warn('thumb upload failed', thumbErr);
+      } else {
+        thumbStoragePath = thumbPath;
+        thumbNonceB64 = await toBase64(thumbNonce);
+      }
+      // Wipe nonce buffer.
+      for (let i = 0; i < thumbNonce.length; i++) thumbNonce[i] = 0;
+    } catch (err: unknown) {
+      console.warn('thumb encrypt/upload failed', err);
+    }
+  }
+
   const handle: AttachmentHandle = {
     id,
     storagePath,
@@ -277,6 +322,8 @@ export async function encryptAndUploadAttachment(params: {
     ...(params.height !== undefined ? { height: params.height } : {}),
     keyB64: await toBase64(key),
     nonceB64: await toBase64(nonce),
+    ...(thumbStoragePath !== undefined ? { thumbStoragePath } : {}),
+    ...(thumbNonceB64 !== undefined ? { thumbNonceB64 } : {}),
   };
 
   return { handle, key, nonce };
@@ -309,6 +356,51 @@ export async function downloadAndDecryptAttachment(params: {
   return new Blob([copy.buffer], { type: params.handle.mimeType });
 }
 
+// Download + decrypt the small WebP preview thumb that the sender uploaded
+// alongside an image attachment (Phase 6B optimisation). Returns `null` if
+// the handle has no thumb metadata (pre-Phase-6B message) or if the thumb
+// blob is missing from storage — caller falls back to the full image.
+//
+// We deliberately swallow ANY download error (missing object, transient
+// 5xx) so the receiver gracefully degrades to the full-blob path; only a
+// successful decrypt-failure throws, since that signals a real corruption.
+export async function downloadAndDecryptAttachmentThumb(params: {
+  client: AppSupabaseClient;
+  handle: AttachmentHandle;
+}): Promise<Blob | null> {
+  if (!params.handle.thumbStoragePath || !params.handle.thumbNonceB64) {
+    return null;
+  }
+  const backend = getCryptoBackend();
+
+  let data: Blob | null = null;
+  try {
+    const res = await params.client.storage
+      .from(ATTACHMENT_BUCKET)
+      .download(params.handle.thumbStoragePath);
+    if (res.error) {
+      // Likely 404 — sender failed to upload thumb, or it's been GC'd.
+      // Receiver falls back to full image.
+      return null;
+    }
+    data = res.data;
+  } catch {
+    return null;
+  }
+  if (!data) return null;
+
+  const ciphertext = new Uint8Array(await data.arrayBuffer());
+  const key = await fromBase64(params.handle.keyB64);
+  const nonce = await fromBase64(params.handle.thumbNonceB64);
+  const plainBytes = backend.secretboxOpen(ciphertext, nonce, key);
+  for (let i = 0; i < key.length; i++) key[i] = 0;
+  for (let i = 0; i < nonce.length; i++) nonce[i] = 0;
+  const copy = new Uint8Array(plainBytes.byteLength);
+  copy.set(plainBytes);
+  // Thumbs are always image/webp regardless of original mime.
+  return new Blob([copy.buffer], { type: 'image/webp' });
+}
+
 // Insert the public metadata row for an attachment. The ciphertext itself has
 // already been uploaded to storage under `handle.storagePath`.
 export async function insertAttachmentRow(

packages/shared/src/i18n/locales/de/app.json

@@ -53,8 +53,6 @@
     "archive": "Archivieren",
     "unarchive": "Entarchivieren",
     "archived_title": "Archiv",
-    "show_archived": "Archiv anzeigen",
-    "show_active": "Aktive anzeigen",
     "archived_empty_title": "Nichts archiviert",
     "archived_empty_subtitle": "Archivierte Unterhaltungen erscheinen hier.",
     "mute": "Stummschalten",
@@ -84,8 +82,6 @@
     "join": "Beitreten",
     "in_call": "Im Anruf",
     "waiting_for_peers": "Warte auf andere…",
-    "voice_connected": "Sprachchat verbunden",
-    "still_live": "Anruf läuft noch",
     "share_screen": "Bildschirm teilen",
     "stop_share_screen": "Screen-Share stoppen",
     "is_sharing_screen": "{{name}} teilt den Bildschirm",
@@ -133,11 +129,9 @@
     "action_unfriend": "Entfernen",
     "action_accept": "Annehmen",
     "action_decline": "Ablehnen",
-    "action_cancel": "Abbrechen",
+    "action_cancel": "Abbrechen"
-    "confirm_unfriend": "Diesen Freund entfernen?"
   },
   "admin": {
-    "nav": "Admin",
     "title": "Admin-Panel",
     "settings_title": "Globale Einstellungen",
     "invites_enabled": "Neue Registrierungen erlauben",
@@ -188,15 +182,11 @@
     "screen_share_quality": "Qualität",
     "screen_share_hint": "WebRTC passt Bitrate + Auflösung dynamisch an die Netzwerkqualität an (SVC/VP9). Die Werte sind Obergrenzen. Änderungen greifen beim nächsten Call.",
     "language": "Sprache",
-    "presence": "Status",
     "show_read_receipts": "Lesebestätigungen anzeigen",
     "show_read_receipts_hint": "Wenn aus, sehen andere nicht wann du ihre Nachrichten gelesen hast — und du siehst nicht wann sie deine gelesen haben.",
     "allow_dms_strangers": "DMs von Fremden erlauben",
     "allow_dms_strangers_hint": "Wenn aus, können dich nur Freunde direkt anschreiben.",
-    "this_device": "Dieses Gerät",
-    "danger_zone": "Gefahrenzone",
     "sign_out": "Abmelden",
-    "section_ringtone": "Klingelton",
     "ringtone_incoming": "Eingehender Anruf",
     "ringtone_default_active": "Standard-Klingelton (Doppelton)",
     "ringtone_custom_active": "{{name}} · {{size}} MB",

packages/shared/src/i18n/locales/de/auth.json

@@ -50,28 +50,8 @@
   "footer_studio": "Supabase Studio",
   "legal_note": "Mit der Registrierung akzeptierst du, dass der Server nur Chiffretext sieht.",
   "signed_in": {
-    "title": "Angemeldet",
-    "session_active": "Sitzung aktiv",
-    "user_id": "Benutzer-ID",
     "email": "E-Mail",
     "username": "Benutzername",
-    "display_name": "Anzeigename",
+    "display_name": "Anzeigename"
-    "admin": "Admin",
-    "yes": "Ja",
-    "no": "Nein",
-    "sign_out": "Abmelden",
-    "device_active": "Aktives Gerät",
-    "device_platform": "Plattform",
-    "device_registered_at": "Registriert"
-  },
-  "device": {
-    "title": "Dieses Gerät registrieren",
-    "subtitle": "Erzeugt ein X25519-Schlüsselpaar. Der private Schlüssel bleibt auf diesem Gerät.",
-    "name_label": "Gerätename",
-    "name_hint": "Erscheint in deiner Geräteliste. Wähle einen erkennbaren Namen.",
-    "name_placeholder": "Dennis Laptop",
-    "cta": "Gerät registrieren",
-    "cta_loading": "Schlüsselpaar wird erzeugt…",
-    "security_note_dev": "Dev-Build: Privater Schlüssel liegt unverschlüsselt im localStorage. Stronghold folgt vor dem Release."
   }
 }

packages/shared/src/i18n/locales/de/common.json

@@ -1,16 +1,8 @@
 {
   "app_name": "ChatApp",
-  "loading": "Lädt…",
   "finalising_session": "Sitzung wird abgeschlossen…",
-  "cancel": "Abbrechen",
   "save": "Speichern",
   "close": "Schließen",
-  "retry": "Wiederholen",
-  "online": "Online",
-  "offline": "Offline",
-  "idle": "Abwesend",
-  "dnd": "Nicht stören",
-  "invisible": "Unsichtbar",
   "local_stack_online": "Lokaler Stack online",
   "dev_build": "Dev-Build"
 }

packages/shared/src/i18n/locales/en/app.json

@@ -53,8 +53,6 @@
     "archive": "Archive",
     "unarchive": "Unarchive",
     "archived_title": "Archive",
-    "show_archived": "Show archive",
-    "show_active": "Show active",
     "archived_empty_title": "Nothing archived",
     "archived_empty_subtitle": "Archived conversations appear here.",
     "mute": "Mute",
@@ -84,8 +82,6 @@
     "join": "Join",
     "in_call": "In call",
     "waiting_for_peers": "Waiting for others…",
-    "voice_connected": "Voice connected",
-    "still_live": "Call still live",
     "share_screen": "Share screen",
     "stop_share_screen": "Stop sharing",
     "is_sharing_screen": "{{name}} is sharing their screen",
@@ -133,11 +129,9 @@
     "action_unfriend": "Unfriend",
     "action_accept": "Accept",
     "action_decline": "Decline",
-    "action_cancel": "Cancel",
+    "action_cancel": "Cancel"
-    "confirm_unfriend": "Remove this friend?"
   },
   "admin": {
-    "nav": "Admin",
     "title": "Admin panel",
     "settings_title": "Global settings",
     "invites_enabled": "Allow new signups",
@@ -188,15 +182,11 @@
     "screen_share_quality": "Quality",
     "screen_share_hint": "WebRTC dynamically adjusts bitrate + resolution to match network conditions (SVC/VP9). Values are upper bounds. Changes apply on the next call.",
     "language": "Language",
-    "presence": "Presence",
     "show_read_receipts": "Show read receipts",
     "show_read_receipts_hint": "When off, others can't see when you read their messages — and you won't see when they read yours.",
     "allow_dms_strangers": "Allow DMs from strangers",
     "allow_dms_strangers_hint": "When off, only friends can DM you.",
-    "this_device": "This device",
-    "danger_zone": "Danger zone",
     "sign_out": "Sign out",
-    "section_ringtone": "Ringtone",
     "ringtone_incoming": "Incoming call",
     "ringtone_default_active": "Default ringtone (double beep)",
     "ringtone_custom_active": "{{name}} · {{size}} MB",

packages/shared/src/i18n/locales/en/auth.json

@@ -50,28 +50,8 @@
   "footer_studio": "Supabase Studio",
   "legal_note": "By signing up you accept that the server sees only ciphertext.",
   "signed_in": {
-    "title": "Signed in",
-    "session_active": "Session active",
-    "user_id": "User ID",
     "email": "Email",
     "username": "Username",
-    "display_name": "Display name",
+    "display_name": "Display name"
-    "admin": "Admin",
-    "yes": "yes",
-    "no": "no",
-    "sign_out": "Sign out",
-    "device_active": "Active device",
-    "device_platform": "Platform",
-    "device_registered_at": "Registered"
-  },
-  "device": {
-    "title": "Register this device",
-    "subtitle": "Generates an X25519 keypair. Private key stays on this device.",
-    "name_label": "Device name",
-    "name_hint": "Shown to you in your device list. Keep it recognisable.",
-    "name_placeholder": "Dennis Laptop",
-    "cta": "Register device",
-    "cta_loading": "Generating keypair…",
-    "security_note_dev": "Dev build: private key stored unencrypted in localStorage. Stronghold comes before release."
   }
 }

packages/shared/src/i18n/locales/en/common.json

@@ -1,16 +1,8 @@
 {
   "app_name": "ChatApp",
-  "loading": "Loading…",
   "finalising_session": "Finalising session…",
-  "cancel": "Cancel",
   "save": "Save",
   "close": "Close",
-  "retry": "Retry",
-  "online": "Online",
-  "offline": "Offline",
-  "idle": "Idle",
-  "dnd": "Do not disturb",
-  "invisible": "Invisible",
   "local_stack_online": "local stack online",
   "dev_build": "dev build"
 }

pnpm-lock.yaml

@@ -98,6 +98,9 @@ importers:
       react-router-dom:
         specifier: ^6.28.0
         version: 6.30.3(react-dom@18.3.1(react@18.3.1))(react@18.3.1)
+      react-virtuoso:
+        specifier: ^4.18.7
+        version: 4.18.7(react-dom@18.3.1(react@18.3.1))(react@18.3.1)
       zustand:
         specifier: ^5.0.1
         version: 5.0.12(@types/react@18.3.28)(react@18.3.1)(use-sync-external-store@1.6.0(react@18.3.1))
@@ -5420,6 +5423,12 @@ packages:
     peerDependencies:
       react: ^18.3.1
 
+  react-virtuoso@4.18.7:
+    resolution: {integrity: sha512-xNF5zDGEEIMB7cKwcen/pLig0YDf6OnfFrVgKFa7sHPf9fRem0CaLshyObbBcP88jzn0enavL39EgplgdyT21g==}
+    peerDependencies:
+      react: '>=16 || >=17 || >= 18 || >= 19'
+      react-dom: '>=16 || >=17 || >= 18 || >=19'
+
   react@18.3.1:
     resolution: {integrity: sha512-wS+hAgJShR0KhEvPJArfuPVN1+Hz1t0Y6n5jLrGQbkb4urgPE/0Rve+1kMB1v/oWgHgm4WIcV+i7F2pTVj+2iQ==}
     engines: {node: '>=0.10.0'}
@@ -12820,6 +12829,11 @@ snapshots:
       react-shallow-renderer: 16.15.0(react@18.3.1)
       scheduler: 0.23.2
 
+  react-virtuoso@4.18.7(react-dom@18.3.1(react@18.3.1))(react@18.3.1):
+    dependencies:
+      react: 18.3.1
+      react-dom: 18.3.1(react@18.3.1)
+
   react@18.3.1:
     dependencies:
       loose-envify: 1.4.0