feat(tui): add arrow key navigation and screen attach

- Add arrow key navigation in StartScreen (up/down to move)
- Highlight selected session with blue background
- Press Enter to view session in TUI mode
- Press 'a' to attach directly to GNU screen session
- Attach exits TUI and inherits stdio for full terminal control

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/tui/App.tsx

@@ -8,6 +8,7 @@
 
 import React, { useState, useEffect, useCallback } from 'react';
 import { Box, Text, useApp, useInput, useStdout } from 'ink';
+import { execSync, spawnSync } from 'child_process';
 import { StartScreen } from './components/StartScreen.js';
 import { TabBar } from './components/TabBar.js';
 import { TerminalView } from './components/TerminalView.js';
@@ -176,6 +177,28 @@ export function App(): React.ReactElement {
     }
   }, [createSession]);
 
+  /**
+   * Attach directly to a screen session
+   * This exits the TUI and attaches to GNU screen
+   */
+  const handleAttachSession = useCallback((session: ScreenSession) => {
+    // Clear screen and restore terminal
+    process.stdout.write('\x1b[2J\x1b[H');
+    console.log(`Attaching to screen: ${session.screenName}`);
+    console.log('Press Ctrl+A D to detach and return to terminal\n');
+
+    // Use spawnSync to attach to screen (inherits stdio)
+    const result = spawnSync('screen', ['-r', session.screenName], {
+      stdio: 'inherit',
+    });
+
+    // After detaching, exit the TUI
+    if (result.status === 0) {
+      console.log('\nDetached from screen. Run "claudeman tui" to return.');
+    }
+    exit();
+  }, [exit]);
+
   // Render help overlay if shown
   if (showHelp) {
     return <HelpOverlay onClose={() => setShowHelp(false)} />;
@@ -187,6 +210,7 @@ export function App(): React.ReactElement {
       <StartScreen
         sessions={sessions}
         onSelectSession={handleSelectSession}
+        onAttachSession={handleAttachSession}
         onCreateSession={handleCreateSession}
         onRefresh={refreshSessions}
         onExit={exit}

src/tui/components/StartScreen.tsx

@@ -4,16 +4,18 @@
  * Initial screen shown when TUI launches. Displays:
  * - List of existing screen sessions from ~/.claudeman/screens.json
  * - Session status (alive/dead), runtime, mode
- * - Options to select, create, or refresh sessions
+ * - Arrow key navigation with highlighted selection
+ * - Options to select, create, attach, or refresh sessions
  */
 
-import React from 'react';
-import { Box, Text } from 'ink';
+import React, { useState } from 'react';
+import { Box, Text, useInput } from 'ink';
 import type { ScreenSession } from '../../types.js';
 
 interface StartScreenProps {
   sessions: ScreenSession[];
   onSelectSession: (session: ScreenSession) => void;
+  onAttachSession: (session: ScreenSession) => void;
   onCreateSession: () => void;
   onRefresh: () => void;
   onExit: () => void;
@@ -41,16 +43,43 @@ function formatDuration(ms: number): string {
 }
 
 /**
- * Start screen component showing session list
+ * Start screen component showing session list with arrow key navigation
  */
 export function StartScreen({
   sessions,
   onSelectSession,
+  onAttachSession,
   onCreateSession,
   onRefresh,
   onExit,
 }: StartScreenProps): React.ReactElement {
   const now = Date.now();
+  const [selectedIndex, setSelectedIndex] = useState(0);
+
+  // Handle keyboard input for navigation
+  useInput((input, key) => {
+    // Arrow key navigation
+    if (key.upArrow && sessions.length > 0) {
+      setSelectedIndex((prev) => (prev > 0 ? prev - 1 : sessions.length - 1));
+      return;
+    }
+    if (key.downArrow && sessions.length > 0) {
+      setSelectedIndex((prev) => (prev < sessions.length - 1 ? prev + 1 : 0));
+      return;
+    }
+
+    // Enter to view session in TUI
+    if (key.return && sessions.length > 0) {
+      onSelectSession(sessions[selectedIndex]);
+      return;
+    }
+
+    // 'a' to attach directly to screen
+    if (input === 'a' && sessions.length > 0 && sessions[selectedIndex].attached) {
+      onAttachSession(sessions[selectedIndex]);
+      return;
+    }
+  });
 
   return (
     <Box flexDirection="column" padding={1}>
@@ -82,7 +111,7 @@ export function StartScreen({
           {/* Table header */}
           <Box marginBottom={1}>
             <Text bold>
-              <Text color="gray">{' #  '}</Text>
+              <Text color="gray">{'    '}</Text>
               <Text>{'NAME'.padEnd(22)}</Text>
               <Text>{'RUNTIME'.padEnd(12)}</Text>
               <Text>{'STATUS'.padEnd(10)}</Text>
@@ -97,19 +126,31 @@ export function StartScreen({
             const statusIcon = session.attached ? '\u25CF' : '\u25CB';
             const statusText = session.attached ? 'alive' : 'dead';
             const name = (session.name || 'unnamed').slice(0, 20);
+            const isSelected = index === selectedIndex;
 
             return (
               <Box key={session.sessionId}>
-                <Text>
-                  <Text color="cyan">[{index + 1}]</Text>
-                  <Text> </Text>
-                  <Text>{name.padEnd(22)}</Text>
-                  <Text dimColor>{runtime.padEnd(12)}</Text>
-                  <Text color={statusColor}>
-                    {statusIcon} {statusText.padEnd(8)}
+                {isSelected ? (
+                  <Text backgroundColor="blue" color="white">
+                    <Text color="cyan" bold>{' \u25B6 '}</Text>
+                    <Text bold>{name.padEnd(22)}</Text>
+                    <Text>{runtime.padEnd(12)}</Text>
+                    <Text color={statusColor}>
+                      {statusIcon} {statusText.padEnd(8)}
+                    </Text>
+                    <Text>{session.mode.padEnd(10)}</Text>
                   </Text>
-                  <Text>{session.mode.padEnd(10)}</Text>
-                </Text>
+                ) : (
+                  <Text>
+                    <Text color="gray">{'   '}</Text>
+                    <Text>{name.padEnd(22)}</Text>
+                    <Text dimColor>{runtime.padEnd(12)}</Text>
+                    <Text color={statusColor}>
+                      {statusIcon} {statusText.padEnd(8)}
+                    </Text>
+                    <Text>{session.mode.padEnd(10)}</Text>
+                  </Text>
+                )}
               </Box>
             );
           })}
@@ -121,15 +162,17 @@ export function StartScreen({
         <Box borderStyle="single" borderColor="gray" paddingX={1}>
           <Text>
             <Text color="green">[n]</Text>
-            <Text> New session  </Text>
-            <Text color="green">[1-9]</Text>
-            <Text> Select  </Text>
+            <Text> New  </Text>
+            <Text color="green">[{'\u2191\u2193'}]</Text>
+            <Text> Navigate  </Text>
+            <Text color="green">[Enter]</Text>
+            <Text> View  </Text>
+            <Text color="green">[a]</Text>
+            <Text> Attach  </Text>
             <Text color="green">[r]</Text>
             <Text> Refresh  </Text>
             <Text color="yellow">[q]</Text>
-            <Text> Quit  </Text>
-            <Text color="blue">[?]</Text>
-            <Text> Help</Text>
+            <Text> Quit</Text>
           </Text>
         </Box>
       </Box>