Fix terminal size detection + proper resize handling

- Connect resize handler to process channel
- Re-fetch terminal size before each render
- Improved screen clearing to remove artifacts
- Added debug logging for terminal size changes

src/shellmate/ssh/server.py

@@ -53,22 +53,32 @@ class TerminalSession:
         self.process = process
         self.width = 80
         self.height = 24
-        self._update_size()
         self._resize_event = asyncio.Event()
+        self._update_size()
+        
+        # Connect resize handler to process
+        process.channel.set_terminal_size_handler(self.handle_resize)
     
     def _update_size(self):
         """Update terminal size from process."""
-        size = self.process.get_terminal_size()
-        if size:
-            self.width = max(size[0], 40)
-            self.height = max(size[1], 10)
+        try:
+            size = self.process.get_terminal_size()
+            if size and len(size) >= 2:
+                w, h = size[0], size[1]
+                if w > 0:
+                    self.width = max(w, 40)
+                if h > 0:
+                    self.height = max(h, 10)
+                logger.debug(f"Terminal size updated: {self.width}x{self.height}")
+        except Exception as e:
+            logger.warning(f"Could not get terminal size: {e}")
     
     def handle_resize(self, width, height, pixwidth, pixheight):
         """Handle terminal resize event."""
+        logger.debug(f"Resize event: {width}x{height}")
         self.width = max(width, 40)
         self.height = max(height, 10)
         self._resize_event.set()
-        self._resize_event.clear()
     
     def write(self, data: str):
         """Write string data to terminal."""
@@ -77,8 +87,9 @@ class TerminalSession:
         self.process.stdout.write(data)
     
     def clear(self):
-        """Clear screen and move cursor home."""
-        self.write("\033[2J\033[H")
+        """Clear screen completely and move cursor home."""
+        # Reset scrolling region, clear entire screen, move to home
+        self.write("\033[r\033[2J\033[3J\033[H")
     
     def hide_cursor(self):
         self.write("\033[?25l")
@@ -142,6 +153,9 @@ async def run_simple_menu(process, session: TerminalSession, username: str, mode
     
     def render_menu():
         """Render the main menu centered on screen."""
+        # Re-fetch terminal size before rendering
+        session._update_size()
+        
         writer = ProcessWriter(session)
         console = Console(file=writer, width=session.width, height=session.height, force_terminal=True, color_system="truecolor")