fix: session restoration now properly attaches to existing screens

- Pass existing screenSession to Session constructor for restored sessions
- Skip terminal buffer clearing when attaching to restored (existing) screens
- Frontend auto-calls /interactive endpoint when selecting a restored session
- Fixes issue where restored sessions appeared broken after server restart

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

src/session.ts

@@ -129,6 +129,7 @@ export class Session extends EventEmitter {
     name?: string;
     screenManager?: ScreenManager;
     useScreen?: boolean;
+    screenSession?: ScreenSession;  // For restored sessions - pass the existing screen
   }) {
     super();
     this.id = config.id || uuidv4();
@@ -139,6 +140,7 @@ export class Session extends EventEmitter {
     this._lastActivityAt = this.createdAt;
     this._screenManager = config.screenManager || null;
     this._useScreen = config.useScreen ?? (this._screenManager !== null && ScreenManager.isScreenAvailable());
+    this._screenSession = config.screenSession || null;  // Use existing screen if provided
 
     // Initialize task tracker and forward events
     this._taskTracker = new TaskTracker();
@@ -379,14 +381,21 @@ export class Session extends EventEmitter {
 
     console.log('[Session] Starting interactive Claude session' + (this._useScreen ? ' (with screen)' : ''));
 
-    // If screen wrapping is enabled, create a screen session first
+    // If screen wrapping is enabled, create or attach to a screen session
     if (this._useScreen && this._screenManager) {
       try {
-        this._screenSession = await this._screenManager.createScreen(this.id, this.workingDir, 'claude', this._name);
-        console.log('[Session] Created screen session:', this._screenSession.screenName);
+        // Check if we already have a screen session (restored session)
+        const isRestoredSession = this._screenSession !== null;
+        if (isRestoredSession) {
+          console.log('[Session] Attaching to existing screen session:', this._screenSession.screenName);
+        } else {
+          // Create a new screen session
+          this._screenSession = await this._screenManager.createScreen(this.id, this.workingDir, 'claude', this._name);
+          console.log('[Session] Created screen session:', this._screenSession.screenName);
 
-        // Wait a moment for screen to fully start
-        await new Promise(resolve => setTimeout(resolve, 300));
+          // Wait a moment for screen to fully start
+          await new Promise(resolve => setTimeout(resolve, 300));
+        }
 
         // Attach to the screen session via PTY
         this.ptyProcess = pty.spawn('screen', [
@@ -399,12 +408,14 @@ export class Session extends EventEmitter {
           env: { ...process.env, TERM: 'xterm-256color' },
         });
 
-        // Screen creates blank space when initializing. After attaching, wait for
-        // the initial burst then clear the buffer and tell clients to clear their terminal.
-        setTimeout(() => {
-          this._terminalBuffer = '';
-          this.emit('clearTerminal');
-        }, 100);
+        // For NEW screens: clear buffer after initial burst (screen initialization noise)
+        // For RESTORED screens: don't clear - we want to see the existing output
+        if (!isRestoredSession) {
+          setTimeout(() => {
+            this._terminalBuffer = '';
+            this.emit('clearTerminal');
+          }, 100);
+        }
       } catch (err) {
         console.error('[Session] Failed to create screen session, falling back to direct PTY:', err);
         this._useScreen = false;
@@ -510,14 +521,21 @@ export class Session extends EventEmitter {
     const shell = process.env.SHELL || '/bin/bash';
     console.log('[Session] Starting shell session with:', shell + (this._useScreen ? ' (with screen)' : ''));
 
-    // If screen wrapping is enabled, create a screen session first
+    // If screen wrapping is enabled, create or attach to a screen session
     if (this._useScreen && this._screenManager) {
       try {
-        this._screenSession = await this._screenManager.createScreen(this.id, this.workingDir, 'shell', this._name);
-        console.log('[Session] Created screen session:', this._screenSession.screenName);
+        // Check if we already have a screen session (restored session)
+        const isRestoredSession = this._screenSession !== null;
+        if (isRestoredSession) {
+          console.log('[Session] Attaching to existing screen session:', this._screenSession.screenName);
+        } else {
+          // Create a new screen session
+          this._screenSession = await this._screenManager.createScreen(this.id, this.workingDir, 'shell', this._name);
+          console.log('[Session] Created screen session:', this._screenSession.screenName);
 
-        // Wait a moment for screen to fully start
-        await new Promise(resolve => setTimeout(resolve, 300));
+          // Wait a moment for screen to fully start
+          await new Promise(resolve => setTimeout(resolve, 300));
+        }
 
         // Attach to the screen session via PTY
         this.ptyProcess = pty.spawn('screen', [
@@ -530,14 +548,16 @@ export class Session extends EventEmitter {
           env: { ...process.env, TERM: 'xterm-256color' },
         });
 
-        // Screen creates blank space when initializing. After attaching, wait for
-        // the initial burst then clear by sending 'clear' command to the shell.
-        setTimeout(() => {
-          if (this.ptyProcess) {
-            this._terminalBuffer = '';
-            this.ptyProcess.write('clear\n');
-          }
-        }, 100);
+        // For NEW screens: clear by sending 'clear' command to the shell
+        // For RESTORED screens: don't clear - we want to see the existing output
+        if (!isRestoredSession) {
+          setTimeout(() => {
+            if (this.ptyProcess) {
+              this._terminalBuffer = '';
+              this.ptyProcess.write('clear\n');
+            }
+          }, 100);
+        }
       } catch (err) {
         console.error('[Session] Failed to create screen session, falling back to direct PTY:', err);
         this._useScreen = false;

src/web/public/app.js

@@ -633,6 +633,19 @@ class ClaudemanApp {
     this.activeSessionId = sessionId;
     this.renderSessionTabs();
 
+    // Check if this is a restored session that needs to be attached
+    const session = this.sessions.get(sessionId);
+    if (session && session.pid === null && session.status === 'idle') {
+      // This is a restored session - attach to the existing screen
+      try {
+        await fetch(`/api/sessions/${sessionId}/interactive`, { method: 'POST' });
+        // Update local session state
+        session.status = 'busy';
+      } catch (err) {
+        console.error('Failed to attach to restored session:', err);
+      }
+    }
+
     // Load terminal buffer for this session
     try {
       const res = await fetch(`/api/sessions/${sessionId}/terminal`);

src/web/server.ts

@@ -1393,14 +1393,15 @@ export class WebServer extends EventEmitter {
         const screens = this.screenManager.getScreens();
         for (const screen of screens) {
           if (!this.sessions.has(screen.sessionId)) {
-            // Create a session object for this screen
+            // Create a session object for this screen with the existing screenSession
             const session = new Session({
               id: screen.sessionId,  // Preserve the original session ID
               workingDir: screen.workingDir,
               mode: screen.mode,
               name: screen.name || screen.screenName,
               screenManager: this.screenManager,
-              useScreen: true
+              useScreen: true,
+              screenSession: screen  // Pass the existing screen so startInteractive() can attach to it
             });
 
             this.sessions.set(session.id, session);