lotus(#6): render decoration in MediaView; fix store lifecycle

Review found in-call tiles use MediaView->Avatar, not TileAvatar, so the
decoration never rendered in-call (CRITICAL). Move the overlay into
MediaView, gated on the avatar's own visibility (!(video && videoEnabled))
so it never floats over live video; revert the TileAvatar changes.
Also ref-count the io.lotus.decorations registration (one shared handler,
no double-reply) and stop clearing the map on teardown so a transient
remount doesn't drop decorations (HIGH/MED).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/lotus/lotusDecorations.ts

@@ -47,34 +47,51 @@ function safeImageUrl(raw: unknown): string | null {
   }
 }
 
+// Ref-counted single registration: the decoration roster is app-wide (keyed by
+// userId), so multiple tile/InCallView mounts must share ONE handler — otherwise
+// each would reply to the same widget request (double-reply) and a transient
+// remount would tear it down.
+let registrations = 0;
+let unregister: (() => void) | null = null;
+
 /**
- * Register the `io.lotus.decorations` handler. No effect unless the host sends
- * the action. Returns a teardown function.
+ * Register the `io.lotus.decorations` handler (ref-counted). No effect unless
+ * the host sends the action. Returns a teardown function.
  */
 export function startLotusDecorations(): () => void {
   const w = widget;
   if (!w) return () => undefined;
 
-  const handler = (ev: CustomEvent<IWidgetApiRequest>): void => {
-    void w.api.transport.reply(ev.detail, {});
-    const data = ev.detail.data as
-      | { decorations?: Record<string, unknown> }
-      | undefined;
-    const next: Record<string, string> = {};
-    if (data?.decorations && typeof data.decorations === "object") {
-      for (const [userId, url] of Object.entries(data.decorations)) {
-        const safe = safeImageUrl(url);
-        if (safe) next[userId] = safe;
+  if (registrations === 0) {
+    const handler = (ev: CustomEvent<IWidgetApiRequest>): void => {
+      void w.api.transport.reply(ev.detail, {});
+      const data = ev.detail.data as
+        | { decorations?: Record<string, unknown> }
+        | undefined;
+      const next: Record<string, string> = {};
+      if (data?.decorations && typeof data.decorations === "object") {
+        for (const [userId, url] of Object.entries(data.decorations)) {
+          const safe = safeImageUrl(url);
+          if (safe) next[userId] = safe;
+        }
       }
-    }
-    decorations = next;
-    emit();
-  };
+      decorations = next;
+      emit();
+    };
+    w.lazyActions.on(LotusWidgetActions.Decorations, handler);
+    unregister = () =>
+      w.lazyActions.off(LotusWidgetActions.Decorations, handler);
+  }
+  registrations += 1;
 
-  w.lazyActions.on(LotusWidgetActions.Decorations, handler);
   return () => {
-    w.lazyActions.off(LotusWidgetActions.Decorations, handler);
-    decorations = {};
-    emit();
+    registrations -= 1;
+    if (registrations <= 0) {
+      registrations = 0;
+      unregister?.();
+      unregister = null;
+      // Intentionally keep the last decorations map: a transient remount must
+      // not drop decorations until the host next pushes an update.
+    }
   };
 }

src/tile/MediaView.module.css

@@ -61,6 +61,24 @@ Please see LICENSE in the repository root for full details.
   mix-blend-mode: multiply;
 }
 
+/* [lotus #6] Profile decoration overlaid on the tile avatar. Shares the
+avatar's centred box and size so frame-style decorations sit around it. */
+.lotusDecoration {
+  position: absolute;
+  top: 50%;
+  left: 50%;
+  transform: translate(-50%, -50%);
+  pointer-events: none;
+  object-fit: contain;
+}
+
+@container mediaView (width > 0) {
+  .lotusDecoration {
+    inline-size: 50cqmin;
+    block-size: 50cqmin;
+  }
+}
+
 /* CSS makes us put a condition here, even though all we want to do is
 unconditionally select the container so we can use cqmin units */
 @container mediaView (width > 0) {

src/tile/MediaView.tsx

@@ -22,6 +22,7 @@ import { ErrorSolidIcon } from "@vector-im/compound-design-tokens/assets/web/ico
 
 import styles from "./MediaView.module.css";
 import { Avatar } from "../Avatar";
+import { useLotusDecoration } from "../lotus/lotusDecorations";
 import { RaisedHandIndicator } from "../reactions/RaisedHandIndicator";
 import {
   showConnectionStats as showConnectionStatsSetting,
@@ -91,6 +92,7 @@ export const MediaView: FC<Props> = ({
   ...props
 }) => {
   const { t } = useTranslation();
+  const decoration = useLotusDecoration(userId);
   const [handRaiseTimerVisible] = useSetting(showHandRaisedTimer);
   const [showConnectionStats] = useSetting(showConnectionStatsSetting);
 
@@ -137,6 +139,17 @@ export const MediaView: FC<Props> = ({
           })}
           style={{ display: video && videoEnabled ? "none" : "initial" }}
         />
+        {decoration && !(video && videoEnabled) && (
+          // [lotus #6] Profile decoration overlay, shown only when the avatar
+          // is visible (i.e. not when live video is showing). Pushed by the
+          // host via io.lotus.decorations; undefined unless opted in.
+          <img
+            className={styles.lotusDecoration}
+            src={decoration}
+            alt=""
+            aria-hidden
+          />
+        )}
         {video?.publication !== undefined && (
           <VideoTrack
             trackRef={video}

src/tile/TileAvatar.module.css

@@ -18,20 +18,3 @@ Please see LICENSE in the repository root for full details.
   /* TODO: make this --cpd-color-fg-primary when available. */
   color: var(--cpd-color-text-primary);
 }
-
-/* [lotus #6] Wrap so the decoration can overlay the avatar precisely. */
-.container {
-  position: relative;
-  display: inline-flex;
-}
-
-/* [lotus #6] APNG/PNG profile decoration drawn over the in-call tile avatar.
-The decoration art shares the avatar's box (transparent padding, ring at the
-edges), matching how the host renders it elsewhere. */
-.lotusDecoration {
-  position: absolute;
-  inset: 0;
-  margin: auto;
-  pointer-events: none;
-  object-fit: contain;
-}

src/tile/TileAvatar.tsx

@@ -10,7 +10,6 @@ import { InlineSpinner } from "@vector-im/compound-web";
 
 import styles from "./TileAvatar.module.css";
 import { Avatar, type Props as AvatarProps } from "../Avatar";
-import { useLotusDecoration } from "../lotus/lotusDecorations";
 
 interface Props extends AvatarProps {
   size: number;
@@ -18,26 +17,14 @@ interface Props extends AvatarProps {
 }
 
 export const TileAvatar: FC<Props> = ({ size, loading, ...props }) => {
-  // [lotus #6] Profile decoration overlay for this participant, pushed by the
-  // host via io.lotus.decorations. undefined unless the host opted in.
-  const decoration = useLotusDecoration(props.id);
   return (
-    <div className={styles.container}>
+    <div>
       {loading && (
         <div className={styles.loading}>
           <InlineSpinner size={size / 3} />
         </div>
       )}
       <Avatar size={size} {...props} />
-      {decoration && (
-        <img
-          className={styles.lotusDecoration}
-          src={decoration}
-          alt=""
-          aria-hidden
-          style={{ width: size, height: size }}
-        />
-      )}
     </div>
   );
 };