refactor(shell): address review feedback on background-shell wording

- Replace hardcoded `italic` tab styling with a semantic `tab-unviewed`
  Tailwind utility (styles.css) so the intent — an unviewed tab — is named.
- Reword the auto-close prompt buttons: "Keep open" -> "Do not close",
  "Close when done" -> "Close if successful" (and matching comments).
- Tighten the create_shell MCP `background` and `close_delay` arg
  descriptions in mcp-bridge.js.

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

Author: big-guy

resources/mcp-bridge.js

@@ -372,12 +372,12 @@ const TOOLS = [
         background: {
           type: 'boolean',
           description:
-            'When true, the tab is created without switching the UI to it, and its title renders italic until selected. Use for commands you want to run without interrupting the user. Defaults to false.'
+            'When true, the tab is created in the background. Use for commands you want to run without interrupting the user. Defaults to false.'
         },
         close_delay: {
           type: 'number',
           description:
-            'Seconds (integer >= 0) to wait after the command finishes successfully before auto-closing the tab. 0 closes immediately on success. Failed commands never auto-close, and a tab the user is actively viewing will not close. Defaults to 30.'
+            'Seconds (integer >= 0) to wait after the command finishes successfully before closing the tab. 0 closes immediately on success. Defaults to 30.'
         }
       }
     }

src/renderer/components/TerminalPanel.tsx

@@ -314,7 +314,7 @@ function SortableTab({ tab, isActive, status, shellActivity, showClose, onSelect
           aria-label="Rename tab"
         />
       ) : (
-        <span className={tab.background ? 'italic' : undefined}>{displayLabel}</span>
+        <span className={tab.background ? 'tab-unviewed' : undefined}>{displayLabel}</span>
       )}
       <TabProgressBar terminalId={tab.id} />
       {showClose && (

src/renderer/components/XTerminal.tsx

@@ -254,7 +254,7 @@ interface XTerminalProps {
   /** Shell tabs only: auto-close delay in seconds, or undefined when not
    * armed. When set, an overlay banner offers to keep the tab open. */
   shellCloseDelay?: number
-  /** Disarm the shell tab's auto-close (the "Keep open" action). */
+  /** Disarm the shell tab's auto-close (the "Do not close" action). */
   onKeepOpen?: () => void
   onRestartAgent?: () => void
   /** When provided AND this is a Claude agent tab, an overlay chip in
@@ -270,8 +270,9 @@ export function XTerminal({ terminalId, cwd, type, agentKind, visible, sessionNa
   const backend = useBackend()
   const chatPromotionDismissed = useSettings().chatPromotionDismissed
   const [exited, setExited] = useState(false)
-  // Local-only: hides the auto-close prompt after "Close when done" without
-  // disarming the behavior. "Keep open" instead clears closeDelay in state.
+  // Local-only: hides the auto-close prompt after "Close if successful"
+  // without disarming the behavior. "Do not close" instead clears closeDelay
+  // in state.
   const [closePromptDismissed, setClosePromptDismissed] = useState(false)
   const containerRef = useRef<HTMLDivElement>(null)
   const terminalRef = useRef<Terminal | null>(null)
@@ -914,14 +915,14 @@ export function XTerminal({ terminalId, cwd, type, agentKind, visible, sessionNa
               onClick={() => { onKeepOpen(); setClosePromptDismissed(true) }}
               className="flex items-center gap-1.5 px-2 py-1 rounded-md text-xs bg-panel/90 border border-border text-fg-bright hover:bg-border transition-colors"
             >
-              <span>Keep open</span>
+              <span>Do not close</span>
             </button>
           </Tooltip>
           <button
             onClick={() => setClosePromptDismissed(true)}
             className="px-2 py-1 rounded-md text-xs bg-panel/90 border border-border text-dim hover:text-fg-bright transition-colors"
           >
-            Close when done
+            Close if successful
           </button>
         </div>
       )}

src/renderer/styles.css

@@ -284,6 +284,12 @@
   height: 2rem;
 }
 
+/* Tab whose contents haven't been viewed yet (e.g. a background shell
+   spawned via the MCP create_shell with background:true, until selected). */
+@utility tab-unviewed {
+  font-style: italic;
+}
+
 @layer base {
   * {
     margin: 0;