fix(desktop): cover fullscreen routes, spare embedded panels

Review round 2 found the two arrangements the collapsed-sidebar selector
alone gets wrong.

A fullscreen route (/upgrade) slides the sidebar to zero width without
collapsing it, so `data-sidebar-collapsed` is absent and the lane stayed
zero while the pane was in fact sitting under the traffic lights. The pane
owns the lane whenever the sidebar is not there to own it, so the selector
now matches a new `data-content-fullscreen` as well.

The mirror error: the variable is inherited, and the mothership panel is
the right half of the pane — never under the lights — yet it embeds whole
pages (KnowledgeBase and friends) whose header bars reserve the lane. Those
bars were gaining ~38px inside the panel. The panel now zeroes the variable
for its subtree.

I had checked for exactly this nesting and concluded it did not exist,
having looked only at the settings pages that import `Resource` types
without rendering `Resource.Header`. `resource-content.tsx` renders the
knowledge page itself, which does.

An assertion each, both verified to fail when the fix is reverted.

Author: Waleed Latif

apps/sim/app/_shell/desktop-title-bar-surfaces.test.ts

@@ -18,6 +18,9 @@ const pageHeaderBar = read('../../components/page-header-bar.ts')
 const resourceHeader = read(
   '../workspace/[workspaceId]/components/resource/components/resource-header/resource-header.tsx'
 )
+const mothershipView = read(
+  '../workspace/[workspaceId]/home/components/mothership-view/mothership-view.tsx'
+)
 
 describe('desktop title-bar surface audit', () => {
   it('applies the safe-area shell only when the auth route is login', () => {
@@ -76,9 +79,21 @@ describe('desktop title-bar surface audit', () => {
     // /organization/[id], /selfhost; the landing tables preview). An undefined var()
     // inside calc() is invalid at computed-value time and drops padding-top entirely.
     expect(globalStyles).toMatch(/:root\s*\{[^}]*--workspace-content-title-bar-inset:\s*0px/s)
-    expect(globalStyles).toContain(
-      '.workspace-content-shell[data-sidebar-collapsed] {\n  --workspace-content-title-bar-inset: var(--desktop-title-bar-height);'
-    )
+    // The pane owns the lane in both arrangements where the sidebar is not there to
+    // own it: collapsed to zero width, and slid away for a fullscreen route (which
+    // leaves the sidebar expanded in the store, so the collapsed selector alone misses
+    // it and /upgrade's back chip lands under the traffic lights).
+    expect(globalStyles).toContain('.workspace-content-shell[data-sidebar-collapsed],')
+    expect(globalStyles).toContain('.workspace-content-shell[data-content-fullscreen] {')
+    expect(workspaceChrome).toContain('data-content-fullscreen={isFullscreen || undefined}')
+  })
+
+  it('clears the lane for panels that embed pages away from the lights', () => {
+    // The mothership panel is the right half of the pane and embeds whole pages
+    // (KnowledgeBase et al) whose header bars reserve the lane. It inherits the
+    // variable, so without this reset those bars gain the inset while sitting nowhere
+    // near the traffic lights.
+    expect(mothershipView).toContain('[--workspace-content-title-bar-inset:0px]')
   })
 
   it('reserves that lane in every top-of-pane header bar', () => {

apps/sim/app/_styles/globals.css

@@ -123,7 +123,10 @@ html[data-sim-desktop-title-bar="inset"]
   letter-spacing: 0.02em;
 }
 
-.workspace-content-shell[data-sidebar-collapsed] {
+/* The pane owns the lane whenever the sidebar is not there to own it: collapsed to
+   zero width, or slid away for a fullscreen route. */
+.workspace-content-shell[data-sidebar-collapsed],
+.workspace-content-shell[data-content-fullscreen] {
   --workspace-content-title-bar-inset: var(--desktop-title-bar-height);
 }
 

apps/sim/app/workspace/[workspaceId]/components/workspace-chrome/workspace-chrome.tsx

@@ -295,6 +295,9 @@ export function WorkspaceChrome({
           isCollapsed && '[[data-sim-desktop-title-bar=inset]_&]:p-0'
         )}
         data-sidebar-collapsed={isCollapsed || undefined}
+        /* A fullscreen route slides the sidebar away without collapsing it, so the pane
+           inherits the traffic-light lane the same way a collapsed sidebar does. */
+        data-content-fullscreen={isFullscreen || undefined}
       >
         <div className='flex-1 overflow-hidden rounded-[8px] border border-[var(--border)] bg-[var(--bg)]'>
           {children}

apps/sim/app/workspace/[workspaceId]/home/components/mothership-view/mothership-view.tsx

@@ -137,6 +137,10 @@ export const MothershipView = memo(
         className={cn(
           'relative z-10 flex h-full flex-col overflow-hidden border-[var(--border)] bg-[var(--bg)] transition-[width,min-width,border-width] duration-200 ease-[cubic-bezier(0.25,0.1,0.25,1)]',
           isCollapsed ? 'w-0 min-w-0 border-l-0' : 'w-1/2 border-l',
+          /* This panel is the right half of the pane, never under the traffic lights,
+             yet it embeds whole pages whose header bars reserve that lane. Zeroing the
+             inherited variable here keeps their top bars flush inside the panel. */
+          '[--workspace-content-title-bar-inset:0px]',
           className
         )}
       >