v1.8.2: session management hardening

- Fix infinite reconnect loop in terminal (_send_to_shell guard)
- Safe language switch: disconnect + reconnect instead of object transplant
- Improved SFTP reconnect flow with proper validation
- Add log.debug to all silent exception handlers in ssh_client

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

gui/tabs/files_tab.py

@@ -450,16 +450,25 @@ class FilesTab(ctk.CTkFrame):
             return items
 
         def _do():
-            try:
-                if not self._sftp.connected:
+            # Ensure connection is alive, reconnect if needed
+            if not self._sftp.connected:
+                try:
                     self._sftp.reconnect()
+                except Exception as e:
+                    self.after(0, lambda: self._on_sftp_error(str(e)))
+                    return
+                if not self._sftp.connected:
+                    self.after(0, lambda: self._on_sftp_error("Reconnect failed"))
+                    return
+
+            try:
                 items = _list_remote()
                 self.after(0, lambda: self._populate_remote(items))
             except PermissionError as e:
                 hint = f"\n{t('try_sudo_hint')}" if not self._sftp.sudo_mode else ""
                 self.after(0, lambda: self._on_sftp_error(str(e) + hint))
             except Exception:
-                # Connection likely dead — try reconnect once
+                # Operation failed — one reconnect attempt
                 try:
                     self._sftp.reconnect()
                     items = _list_remote()

gui/tabs/terminal_tab.py

@@ -142,9 +142,8 @@ class TerminalTab(ctk.CTkFrame):
         session = self._session  # local ref for thread safety
         if session and session.connected:
             session.send(data)
-        elif self._current_alias and not self._intentional_disconnect:
-            # Session dead — trigger reconnect
-            self._reconnect_count = 0
+        elif self._current_alias and not self._intentional_disconnect and self._reconnect_count == 0:
+            # Session dead, no reconnect in progress — trigger one attempt
             self._on_disconnected()
 
     def _on_resize(self, cols: int, rows: int):