Fix critical bugs from second round of testing

1. Fixed infinite loop when closing last tab:
   - Return False instead of True when page already removed (prevents double-processing)
   - Remove from tracking BEFORE calling close_page_finish to prevent re-trigger
   - Properly schedule new tab creation only once

2. Fixed modified flag not clearing after save:
   - Update widget.original_request in _mark_tab_as_saved
   - Update widget.modified = False
   - Manually call _on_tab_modified_changed to clear indicator
   - Update tab page title when saving

3. Fixed header bar height and left spacing:
   - Added CSS to reduce headerbar min-height to 38px
   - Set headerbar padding-left to 0px to eliminate left gap
   - Made tabs more compact (min-height: 26px, reduced padding)
   - Reduced tabbar padding and margins

All critical issues from testing resolved!

src/window.py

@@ -133,9 +133,28 @@ class RosterWindow(Adw.ApplicationWindow):
         """Setup custom CSS for UI styling."""
         css_provider = Gtk.CssProvider()
         css_provider.load_from_data(b"""
-            /* Constrain tab bar to normal header height */
-            .tabbar-box {
+            /* Reduce header bar padding and height */
+            headerbar {
+                min-height: 38px;
+                padding-left: 0px;
+                padding-right: 6px;
+            }
+
+            /* Compact tab bar */
+            tabbar {
                 min-height: 0;
+                padding: 0;
+                margin: 0;
+            }
+
+            tabbar > scrolledwindow {
+                min-height: 0;
+            }
+
+            tabbar tab {
+                min-height: 26px;
+                padding: 2px 8px;
+                margin: 0 1px;
             }
 
             /* Stack switchers styling (Headers/Body tabs) */
@@ -181,8 +200,9 @@ class RosterWindow(Adw.ApplicationWindow):
         tab = self.page_to_tab.get(page)
         widget = self.page_to_widget.get(page)
 
+        # If already removed, allow close (prevents double-processing)
         if not tab or not widget:
-            return True  # Allow close
+            return False  # Allow close
 
         # Check if tab has unsaved changes
         if widget.modified:
@@ -198,10 +218,16 @@ class RosterWindow(Adw.ApplicationWindow):
 
             def on_response(dlg, response):
                 if response == "close":
-                    # Remove from our tracking
+                    # Remove from our tracking FIRST to prevent re-triggering
                     self.tab_manager.close_tab(tab.id)
                     del self.page_to_tab[page]
                     del self.page_to_widget[page]
+
+                    # Check if we need to create a new tab
+                    if self.tab_view.get_n_pages() == 1:  # This page is still counted
+                        # Schedule creating new tab BEFORE closing this one
+                        GLib.idle_add(self._create_new_tab)
+
                     # Close the page
                     tab_view.close_page_finish(page, True)
                 else:
@@ -217,7 +243,7 @@ class RosterWindow(Adw.ApplicationWindow):
             del self.page_to_tab[page]
             del self.page_to_widget[page]
 
-            # If no tabs left, create a new one
+            # If this will be the last tab, create a new one BEFORE returning
             if self.tab_view.get_n_pages() == 1:  # This page is still counted
                 GLib.idle_add(self._create_new_tab)
 
@@ -692,22 +718,38 @@ class RosterWindow(Adw.ApplicationWindow):
 
     def _mark_tab_as_saved(self, saved_request_id, name, request):
         """Mark the current tab as saved (clear modified flag)."""
-        if self.current_tab_id:
-            current_tab = self.tab_manager.get_tab_by_id(self.current_tab_id)
-            if current_tab:
+        page = self.tab_view.get_selected_page()
+        if not page:
+            return
+
+        tab = self.page_to_tab.get(page)
+        widget = self.page_to_widget.get(page)
+
+        if tab and widget:
             # Update tab metadata
-                current_tab.saved_request_id = saved_request_id
-                current_tab.name = name
-                current_tab.modified = False
+            tab.saved_request_id = saved_request_id
+            tab.name = name
+            tab.modified = False
 
             # Update original_request to match saved state
-                current_tab.original_request = HttpRequest(
+            original = HttpRequest(
                 method=request.method,
                 url=request.url,
                 headers=request.headers.copy(),
                 body=request.body,
                 syntax=request.syntax
             )
+            tab.original_request = original
+
+            # Update widget state
+            widget.original_request = original
+            widget.modified = False
+
+            # Update tab page title
+            page.set_title(name)
+
+            # This will trigger the modified-changed signal and clear the indicator
+            self._on_tab_modified_changed(page, False)
 
     def _show_overwrite_dialog(self, project, name, existing_request_id, request):
         """Show dialog asking if user wants to overwrite existing request."""