diff --git a/frontend/src/app/pages/Dashboard/canvas/DashboardCanvas.tsx b/frontend/src/app/pages/Dashboard/canvas/DashboardCanvas.tsx
index b5303ee3..228d1bb9 100644
--- a/frontend/src/app/pages/Dashboard/canvas/DashboardCanvas.tsx
+++ b/frontend/src/app/pages/Dashboard/canvas/DashboardCanvas.tsx
@@ -203,60 +203,8 @@ const DashboardCanvas: React.FC<DashboardCanvasProps> = ({
     return () => window.removeEventListener('mousemove', onMove);
   }, [fullscreenCardId]);
 
-  // Arc/Zen fullscreen: the dock hides with the rest of the chrome but slides back on a left-edge
-  // graze, and clicking a tile SWAPS which card owns the full screen instead of moving the camera.
-  // Hover semantics are a 1:1 port of Zen's compact mode (ZenCompactMode.mjs + compact-mode.yaml):
-  // sidebar-keep-hover 150ms grace after leaving, 1000ms retention when the cursor exits the window
-  // across the dock's screen edge, and an 800ms flash when the active (fullscreen) card switches.
-  const FS_KEEP_HOVER_MS = 150;
-  const FS_WINDOW_LEAVE_MS = 1000;
-  const FS_FLASH_MS = 800;
-  const [fsDockRevealed, setFsDockRevealed] = React.useState(false);
-  const fsDockRef = React.useRef<HTMLDivElement | null>(null);
-  const fsRevealedRef = React.useRef(false);
-  fsRevealedRef.current = fsDockRevealed;
-  useEffect(() => {
-    if (!fullscreenCardId) { setFsDockRevealed(false); return undefined; }
-    let hideTimer: number | null = null;
-    const cancelHide = (): void => { if (hideTimer != null) { window.clearTimeout(hideTimer); hideTimer = null; } };
-    const scheduleHide = (ms: number): void => { cancelHide(); hideTimer = window.setTimeout(() => setFsDockRevealed(false), ms); };
-    const overDock = (x: number, y: number): boolean => {
-      const el = fsDockRef.current;
-      if (!el) return false;
-      const r = el.getBoundingClientRect();
-      return x >= r.left - 8 && x <= r.right + 8 && y >= r.top - 8 && y <= r.bottom + 8;
-    };
-    const onMove = (e: MouseEvent): void => {
-      if (e.clientX <= 16 || overDock(e.clientX, e.clientY)) {
-        cancelHide();
-        if (!fsRevealedRef.current) setFsDockRevealed(true);
-      } else if (fsRevealedRef.current && hideTimer == null) {
-        scheduleHide(FS_KEEP_HOVER_MS);
-      }
-    };
-    // Cursor flung out of the window across the dock's edge: keep the dock up (Zen's screen-edge
-    // retention), then let the next in-window move decide.
-    const onOut = (e: MouseEvent): void => {
-      if (!e.relatedTarget && e.clientX <= 24 && fsRevealedRef.current) scheduleHide(FS_WINDOW_LEAVE_MS);
-    };
-    window.addEventListener('mousemove', onMove);
-    window.addEventListener('mouseout', onOut);
-    return () => { window.removeEventListener('mousemove', onMove); window.removeEventListener('mouseout', onOut); cancelHide(); };
-  }, [fullscreenCardId]);
-  // Zen flashes the sidebar on tab switch in compact mode; swapping the fullscreen card is our tab switch.
-  const prevFsCardRef = React.useRef<string | null>(null);
-  useEffect(() => {
-    const prev = prevFsCardRef.current;
-    prevFsCardRef.current = fullscreenCardId;
-    if (!fullscreenCardId || !prev || prev === fullscreenCardId) return undefined;
-    setFsDockRevealed(true);
-    const t = window.setTimeout(() => {
-      const el = fsDockRef.current;
-      if (el && el.matches(':hover')) return;
-      setFsDockRevealed(false);
-    }, FS_FLASH_MS);
-    return () => window.clearTimeout(t);
-  }, [fullscreenCardId]);
+  // Arc fullscreen layout: the dock rail STAYS PUT (Arc's persistent sidebar) while the card
+  // expands into the whole dashboard beside it; clicking a tile SWAPS which card owns the screen.
   const swapFullscreen = React.useCallback((cardId: string) => {
     if (!fullscreenCardId || cardId === fullscreenCardId) return;
     dispatch(clearTiledCard(fullscreenCardId));
@@ -325,16 +273,11 @@ const DashboardCanvas: React.FC<DashboardCanvasProps> = ({
         />
       )}
 
-      {(!fullscreenCardId || fsDockRevealed) && (
+      {(
         <Box
-          ref={fsDockRef}
           sx={fullscreenCardId ? {
-            // Explicit width: the dock inside is position:absolute so the wrapper would collapse to
-            // its padding, and the hover-keep hit test would miss the dock entirely.
             position: 'absolute', left: 0, top: 0, bottom: 0, width: 64, zIndex: 999995,
             display: 'flex', alignItems: 'center', pl: '4px',
-            animation: 'osw-fsdock-in 160ms ease-out',
-            '@keyframes osw-fsdock-in': { from: { transform: 'translateX(-52px)', opacity: 0 }, to: { transform: 'translateX(0)', opacity: 1 } },
           } : undefined}
         >
           <DesktopDock
diff --git a/frontend/src/app/pages/Dashboard/cards/AgentCard.tsx b/frontend/src/app/pages/Dashboard/cards/AgentCard.tsx
index 1e12171a..44f5da5e 100644
--- a/frontend/src/app/pages/Dashboard/cards/AgentCard.tsx
+++ b/frontend/src/app/pages/Dashboard/cards/AgentCard.tsx
@@ -472,8 +472,10 @@ const AgentCard: React.FC<Props> = ({
   const justDraggedRef = useRef(false);
   const lastPointerRef = useRef<{ clientX: number; clientY: number }>({ clientX: 0, clientY: 0 });
 
+  const tileZone = useAppSelector((s) => s.dashboardLayout.tiledCards[session.id]);
   const handleDragPointerDown = useCallback((e: React.PointerEvent) => {
     if (e.button !== 0) return;
+    if (tileZone) return;
     e.preventDefault();
     e.stopPropagation();
     const cs = getCanvasState();
@@ -483,7 +485,7 @@ const AgentCard: React.FC<Props> = ({
     setIsDragging(true);
     (e.currentTarget as HTMLElement).setPointerCapture(e.pointerId);
     onDragStart?.(session.id, 'agent');
-  }, [cardX, cardY, onDragStart, session.id, getCanvasState]);
+  }, [cardX, cardY, onDragStart, session.id, getCanvasState, tileZone]);
 
   const recomputeDragPos = useCallback(() => {
     const ds = dragState.current;
@@ -656,7 +658,6 @@ const AgentCard: React.FC<Props> = ({
     }
   };
 
-  const tileZone = useAppSelector((s) => s.dashboardLayout.tiledCards[session.id]);
   const isFullscreen = tileZone === 'fullscreen';
   // Fullscreen pins the card to the viewport, so while tiled the geometry must track canvas pan/zoom.
   // Chat cards read the camera via a getter (not props) to avoid re-rendering on every pan tick, so
diff --git a/frontend/src/app/pages/Dashboard/cards/BrowserCard.tsx b/frontend/src/app/pages/Dashboard/cards/BrowserCard.tsx
index 1e7554eb..74312337 100644
--- a/frontend/src/app/pages/Dashboard/cards/BrowserCard.tsx
+++ b/frontend/src/app/pages/Dashboard/cards/BrowserCard.tsx
@@ -712,6 +712,7 @@ const BrowserCard: React.FC<Props> = ({
 
   const handleDragPointerDown = useCallback((e: React.PointerEvent) => {
     if (e.button !== 0) return;
+    if (tileZone) return;
     e.preventDefault();
     e.stopPropagation();
     const cs = getCanvasState();
@@ -721,7 +722,7 @@ const BrowserCard: React.FC<Props> = ({
     setIsDragging(true);
     (e.currentTarget as HTMLElement).setPointerCapture(e.pointerId);
     onDragStart?.(browserId, 'browser');
-  }, [cardX, cardY, onDragStart, browserId, getCanvasState]);
+  }, [cardX, cardY, onDragStart, browserId, getCanvasState, tileZone]);
 
   const recomputeDragPos = useCallback(() => {
     const ds = dragState.current;
diff --git a/frontend/src/app/pages/Dashboard/cards/DashboardViewCard.tsx b/frontend/src/app/pages/Dashboard/cards/DashboardViewCard.tsx
index b13941dd..627e961d 100644
--- a/frontend/src/app/pages/Dashboard/cards/DashboardViewCard.tsx
+++ b/frontend/src/app/pages/Dashboard/cards/DashboardViewCard.tsx
@@ -242,6 +242,7 @@ const DashboardViewCard: React.FC<Props> = ({
 
   const handleDragPointerDown = useCallback((e: React.PointerEvent) => {
     if (e.button !== 0) return;
+    if (tileZone) return;
     e.preventDefault();
     e.stopPropagation();
     const cs = getCanvasState();
@@ -251,7 +252,7 @@ const DashboardViewCard: React.FC<Props> = ({
     setIsDragging(true);
     (e.currentTarget as HTMLElement).setPointerCapture(e.pointerId);
     onDragStart?.(cardKey, 'view');
-  }, [cardX, cardY, onDragStart, cardKey, getCanvasState]);
+  }, [cardX, cardY, onDragStart, cardKey, getCanvasState, tileZone]);
 
   const recomputeDragPos = useCallback(() => {
     const ds = dragState.current;
diff --git a/frontend/src/app/pages/Dashboard/cards/NoteCard.tsx b/frontend/src/app/pages/Dashboard/cards/NoteCard.tsx
index 8a8f599c..809baa99 100644
--- a/frontend/src/app/pages/Dashboard/cards/NoteCard.tsx
+++ b/frontend/src/app/pages/Dashboard/cards/NoteCard.tsx
@@ -108,6 +108,7 @@ const NoteCard: React.FC<Props> = ({
 
   const handleDragPointerDown = useCallback((e: React.PointerEvent) => {
     if (e.button !== 0) return;
+    if (tileZone) return;
     e.preventDefault();
     e.stopPropagation();
     const cs = getCanvasState();
@@ -121,7 +122,7 @@ const NoteCard: React.FC<Props> = ({
     setIsDragging(true);
     (e.currentTarget as HTMLElement).setPointerCapture(e.pointerId);
     onDragStart?.(noteId, 'note');
-  }, [cardX, cardY, noteId, onDragStart, getCanvasState]);
+  }, [cardX, cardY, noteId, onDragStart, getCanvasState, tileZone]);
 
   const recomputeDragPos = useCallback(() => {
     const ds = dragState.current;
diff --git a/frontend/src/app/pages/Dashboard/cards/tileZones.ts b/frontend/src/app/pages/Dashboard/cards/tileZones.ts
index 7434e32b..3d34b755 100644
--- a/frontend/src/app/pages/Dashboard/cards/tileZones.ts
+++ b/frontend/src/app/pages/Dashboard/cards/tileZones.ts
@@ -23,6 +23,8 @@ export const TILE_ZONES: Record<string, { x: number; y: number; w: number; h: nu
 
 // macOS Sequoia leaves a small gap between tiled windows; we match it.
 const GAP = 8;
+// Width the persistent dock rail owns while a card is fullscreen (the Arc sidebar analog).
+export const FULLSCREEN_DOCK_RAIL = 64;
 
 export interface TiledStyle {
   left: number;
@@ -46,20 +48,19 @@ function workspaceSize(): { w: number; h: number } {
 }
 
 export function computeTiledStyle(zone: string, panX: number, panY: number, zoom: number): TiledStyle | null {
-  // 'fullscreen' = macOS full screen: the app chrome hides (AppShell/DashboardCanvas react to
-  // selectFullscreenCardId) and the card covers the WHOLE window. Target is WINDOW space here, so
-  // the viewport origin does NOT cancel; once the chrome collapses that origin goes to ~0 anyway.
+  // 'fullscreen' = the Arc layout: the app chrome hides except the dock rail, which stays put on
+  // the left, and the card expands into the ENTIRE dashboard beside it, floating on the same gap
+  // the tile zones use. Target is WINDOW space here, so the viewport origin does NOT cancel.
   if (zone === 'fullscreen') {
-    const PEEK = 0;
     const el = document.querySelector('[data-canvas-viewport]');
     const r = el ? el.getBoundingClientRect() : null;
     const ox = r ? r.left : 0;
     const oy = r ? r.top : 0;
     return {
-      left: (PEEK - ox - panX) / zoom,
-      top: (PEEK - oy - panY) / zoom,
-      width: window.innerWidth - PEEK * 2,
-      height: window.innerHeight - PEEK * 2,
+      left: (FULLSCREEN_DOCK_RAIL + GAP - ox - panX) / zoom,
+      top: (GAP - oy - panY) / zoom,
+      width: window.innerWidth - FULLSCREEN_DOCK_RAIL - GAP * 2,
+      height: window.innerHeight - GAP * 2,
       transform: `scale(${1 / zoom})`,
       transformOrigin: 'top left',
     };
diff --git a/frontend/src/app/pages/Dashboard/hooks/interaction/useDashboardInteractions.ts b/frontend/src/app/pages/Dashboard/hooks/interaction/useDashboardInteractions.ts
index 1215fca2..c1770936 100644
--- a/frontend/src/app/pages/Dashboard/hooks/interaction/useDashboardInteractions.ts
+++ b/frontend/src/app/pages/Dashboard/hooks/interaction/useDashboardInteractions.ts
@@ -73,6 +73,10 @@ export function useDashboardInteractions({
     // The Workflows window is an app you click around inside, not a card you re-center every tap. Single-click only raises + selects it; double-click still zoom-to-fits (handleCardDoubleClick). Without this, clicking any button inside it yanked the canvas into a re-zoom.
     if (type === 'workflows-hub' || type === 'workflows-monitor') return;
 
+    // A tiled (fullscreen/snapped) card is pinned Arc-style: clicking inside it must not collapse
+    // it or glide the camera; it leaves the mode via its own controls (yellow, Esc, dock swap).
+    if (store.getState().dashboardLayout.tiledCards[id]) return;
+
     const alreadyExpanded = type === 'agent' && expandedSessionIds.includes(id);
 
     if (alreadyExpanded) {
@@ -206,6 +210,7 @@ export function useDashboardInteractions({
     }
     dispatch(bringToFront({ id, type }));
     setFocusedCardId(id);
+    if (store.getState().dashboardLayout.tiledCards[id]) return;
     setTimeout(() => {
       const rect = getCardRect(id, type);
       if (rect) canvas.actions.fitToCards([rect], 1.15, true);