[eric] browser: the docked mini re-measures when its slot announces a remount, retiring a 150ms forever-poll of layout reads

frontend/src/app/pages/AgentChat/AgentChat.tsx

@@ -292,6 +292,10 @@ const AgentChat: React.FC<AgentChatProps> = ({ sessionId: sessionIdProp, onClose
     // The live overlay stamps data-mini-live; while it paints, the frozen-shot backdrop must not (the clamped overlay leaves margins where a misaligned second copy of the page peeked through).
     '&[data-mini-live="1"] img': { opacity: 0 },
   } as const;
+  // The slot announces its own (re)mount so the docked mini re-measures exactly then, instead of polling rects on a timer (the windowed transcript remounts it with no resize/pan event firing).
+  const announceBrowserSlot = useCallback((el: HTMLElement | null) => {
+    if (el) window.dispatchEvent(new CustomEvent('openswarm:browser-slot-mounted', { detail: { id } }));
+  }, [id]);
   // A live webview cannot be clipped by the scroller, so the OVERLAY only shows while fully in view; this frozen shot is what scrolls and clips underneath it, ChatGPT-style.
   const dockedShot = dockedSurfaceId ? getMinimizedShot(dockedSurfaceId) : undefined;
   const browserSlotBody = dockedShot ? (
@@ -1937,7 +1941,7 @@ const AgentChat: React.FC<AgentChatProps> = ({ sessionId: sessionIdProp, onClose
                 return (
                   <React.Fragment key={`${item.id}-with-browser`}>
                     {rendered}
-                    <Box data-browser-slot={id} sx={browserSlotSx}>{browserSlotBody}</Box>
+                    <Box data-browser-slot={id} ref={announceBrowserSlot} sx={browserSlotSx}>{browserSlotBody}</Box>
                   </React.Fragment>
                 );
               }
@@ -2090,7 +2094,7 @@ const AgentChat: React.FC<AgentChatProps> = ({ sessionId: sessionIdProp, onClose
             )}
             {/* Fallback dock slot for a browser that docked before any browser tool row exists (or whose row was compacted away); once a row appears the slot anchors at it instead (see browserAnchorItemId). The real card overlays this rect geometrically, so the webview never remounts; the mini hides itself when its slot scrolls mostly out of view, since a live webview can't be clipped by the scroller. */}
             {hasDockedBrowser && !browserAnchorItemId && (
-              <Box data-browser-slot={id} sx={browserSlotSx}>{browserSlotBody}</Box>
+              <Box data-browser-slot={id} ref={announceBrowserSlot} sx={browserSlotSx}>{browserSlotBody}</Box>
             )}
             </Box>
           </Box>

frontend/src/app/pages/Dashboard/cards/BrowserCard.tsx

@@ -310,18 +310,23 @@ const BrowserCard: React.FC<Props> = ({
     window.addEventListener('openswarm:canvas-pan-changed', measure);
     document.addEventListener('visibilitychange', measure);
     const timers = [60, 250, 700].map((ms) => window.setTimeout(measure, ms));
-    // Self-heal: the slot lives in the WINDOWED transcript and remounts without firing any of the events above, which left the mini scaled against a stale rect (visibly overflowing its frame) until the next pan. 150ms bounds how long any staleness can survive.
-    const heal = window.setInterval(measure, 150);
+    // The slot lives in the WINDOWED transcript and remounts without firing any of the events
+    // above; it announces itself on mount now, which retired a 150ms forever-poll that forced a
+    // layout read ~7x/sec per docked mini even while nothing moved (measure once per real change).
+    const onSlotMounted = (e: Event): void => {
+      if ((e as CustomEvent).detail?.id === dockedTo) measure();
+    };
+    window.addEventListener('openswarm:browser-slot-mounted', onSlotMounted);
     return () => {
       ro.disconnect();
       mo.disconnect();
       window.removeEventListener('resize', measure);
       window.removeEventListener('openswarm:canvas-pan-changed', measure);
       document.removeEventListener('visibilitychange', measure);
+      window.removeEventListener('openswarm:browser-slot-mounted', onSlotMounted);
       scrollHost?.removeEventListener('scroll', onScroll);
       if (scrollRaf) cancelAnimationFrame(scrollRaf);
       timers.forEach((tm) => window.clearTimeout(tm));
-      window.clearInterval(heal);
     };
     // dockParentCard x/y/w/h are re-measure triggers: the slot's client rect moves with the chat card.
   }, [dockedTo, dockParentExpanded, dockParentTiled, dockParentCard?.x, dockParentCard?.y, dockParentCard?.width, dockParentCard?.height, getCanvasState, dockParentCard]);