diff --git a/crates/op-editor-ui/src/widgets/agent_settings_mcp.rs b/crates/op-editor-ui/src/widgets/agent_settings_mcp.rs
index 9886532d5..f5595dcfa 100644
--- a/crates/op-editor-ui/src/widgets/agent_settings_mcp.rs
+++ b/crates/op-editor-ui/src/widgets/agent_settings_mcp.rs
@@ -99,11 +99,11 @@ fn cli_cell_rect(content: Rect, idx: usize) -> Rect {
     }
 }
 
-pub fn hit_test(content: Rect, scrolled: Point2D) -> McpHit {
+pub fn hit_test(content: Rect, settings: &AgentSettings, scrolled: Point2D) -> McpHit {
     if rect_contains(server_button_rect(content), scrolled) {
         return McpHit::ToggleServer;
     }
-    if rect_contains(port_field_rect(content), scrolled) {
+    if !settings.mcp_server.running && rect_contains(port_field_rect(content), scrolled) {
         return McpHit::FocusPort;
     }
     for (i, cli) in McpCli::ALL.iter().enumerate() {
@@ -229,7 +229,8 @@ fn paint_server_card(
         Point2D::new(port_field_x - 8.0 - port_label_w, mid_y + 4.0),
     );
     let port_field = port_field_rect(content);
-    let focused = matches!(settings.focus, Some(SettingsFocus::McpPort));
+    let port_editable = !running;
+    let focused = port_editable && matches!(settings.focus, Some(SettingsFocus::McpPort));
     let port_str = if focused {
         ui.settings_input_draft.clone()
     } else {
@@ -247,7 +248,11 @@ fn paint_server_card(
         &port_str,
         "system-ui",
         12.0,
-        to_jian(theme.foreground),
+        to_jian(if port_editable {
+            theme.foreground
+        } else {
+            theme.muted_foreground
+        }),
         Point2D::new(0.0, 0.0),
     );
     let port_x = port_field.origin.x + (PORT_FIELD_W - port_w) / 2.0;
diff --git a/crates/op-editor-ui/src/widgets/agent_settings_panel.rs b/crates/op-editor-ui/src/widgets/agent_settings_panel.rs
index 769962406..b09be9c28 100644
--- a/crates/op-editor-ui/src/widgets/agent_settings_panel.rs
+++ b/crates/op-editor-ui/src/widgets/agent_settings_panel.rs
@@ -148,7 +148,7 @@ impl<'a> AgentSettingsPanel<'a> {
                 }
             }
             AgentSettingsTab::Mcp => {
-                match agent_settings_mcp::hit_test(content_rect(panel), scrolled) {
+                match agent_settings_mcp::hit_test(content_rect(panel), &self.settings, scrolled) {
                     McpHit::ToggleServer => return AgentSettingsHit::ToggleMcpServer,
                     McpHit::ToggleCli(cli) => return AgentSettingsHit::ToggleMcpCli(cli),
                     McpHit::FocusPort => return AgentSettingsHit::FocusMcpPort,
diff --git a/crates/op-editor-ui/src/widgets/agent_settings_panel_tests.rs b/crates/op-editor-ui/src/widgets/agent_settings_panel_tests.rs
index b6f568d38..bc99bbd07 100644
--- a/crates/op-editor-ui/src/widgets/agent_settings_panel_tests.rs
+++ b/crates/op-editor-ui/src/widgets/agent_settings_panel_tests.rs
@@ -131,3 +131,21 @@ fn hit_test_resolves_builtin_agent_compact_edit_button() {
         AgentSettingsHit::EditBuiltinAgent(0)
     );
 }
+
+#[test]
+fn mcp_port_field_is_not_focusable_while_server_is_running() {
+    let mut state = EditorState::default();
+    state.editor_ui.agent_settings.tab = AgentSettingsTab::Mcp;
+    state.editor_ui.agent_settings.mcp_server.running = true;
+    let panel = AgentSettingsPanel::for_editor(&state);
+    let rect = panel.rect(1200.0, 800.0);
+    let content_x = rect.origin.x + 200.0 + 24.0;
+    let content_y = rect.origin.y + 24.0;
+    let content_w = rect.size.x - 200.0 - 48.0;
+    let server_card_top = content_y + 36.0;
+    let button_x = content_x + content_w - 16.0 - 72.0;
+    let port_x = button_x - 8.0 - 64.0;
+    let point = crate::Point2D::new(port_x + 32.0, server_card_top + 26.0);
+
+    assert_eq!(panel.hit_test(rect, point), AgentSettingsHit::Inside);
+}
diff --git a/crates/op-host-native/src/widget_host/agent_settings_tests.rs b/crates/op-host-native/src/widget_host/agent_settings_tests.rs
index 3767d09f8..335fa1079 100644
--- a/crates/op-host-native/src/widget_host/agent_settings_tests.rs
+++ b/crates/op-host-native/src/widget_host/agent_settings_tests.rs
@@ -1,5 +1,5 @@
 use super::WidgetHostNative;
-use op_editor_core::agent_settings::{BuiltinAgentField, SettingsFocus};
+use op_editor_core::agent_settings::{AgentSettingsTab, BuiltinAgentField, SettingsFocus};
 use op_editor_ui::widgets::agent_settings_panel::AgentSettingsPanel;
 
 #[test]
@@ -109,3 +109,31 @@ fn builtin_agent_compact_edit_focuses_display_name_form() {
         "MiniMax"
     );
 }
+
+#[test]
+fn starting_mcp_server_commits_port_draft_and_clears_focus() {
+    let mut host = WidgetHostNative::new();
+    host.editor_state_mut().editor_ui.agent_settings.tab = AgentSettingsTab::Mcp;
+    host.editor_state_mut().editor_ui.agent_settings.focus = Some(SettingsFocus::McpPort);
+    host.editor_state_mut().editor_ui.settings_input_draft = "3101".into();
+
+    let panel = AgentSettingsPanel::for_editor(host.editor_state());
+    let rect = panel.rect(1200.0, 800.0);
+    let content_x = rect.origin.x + 200.0 + 24.0;
+    let content_y = rect.origin.y + 24.0;
+    let content_w = rect.size.x - 200.0 - 48.0;
+    let server_card_top = content_y + 36.0;
+    let button_x = content_x + content_w - 16.0 - 72.0;
+    assert!(host.dispatch_agent_settings_press(
+        button_x + 36.0,
+        server_card_top + 26.0,
+        1200.0,
+        800.0
+    ));
+
+    let state = host.editor_state();
+    assert!(state.editor_ui.agent_settings.mcp_server.running);
+    assert_eq!(state.editor_ui.agent_settings.mcp_server.port, 3101);
+    assert!(state.editor_ui.agent_settings.focus.is_none());
+    assert!(state.editor_ui.settings_input_draft.is_empty());
+}
diff --git a/crates/op-host-native/src/widget_host/press_helpers.rs b/crates/op-host-native/src/widget_host/press_helpers.rs
index 34eb2ea07..312d49e97 100644
--- a/crates/op-host-native/src/widget_host/press_helpers.rs
+++ b/crates/op-host-native/src/widget_host/press_helpers.rs
@@ -77,6 +77,7 @@ impl WidgetHostNative {
                 self.editor_state.rebuild_chat_models();
             }
             AgentSettingsHit::ToggleMcpServer => {
+                self.commit_settings_focus_if_any();
                 let v = &mut self
                     .editor_state
                     .editor_ui
diff --git a/crates/op-host-web/src/widget_host/press.rs b/crates/op-host-web/src/widget_host/press.rs
index 0512bb4fe..b27f4fd50 100644
--- a/crates/op-host-web/src/widget_host/press.rs
+++ b/crates/op-host-web/src/widget_host/press.rs
@@ -760,6 +760,7 @@ impl WidgetHost {
                 self.editor_state.rebuild_chat_models();
             }
             AgentSettingsHit::ToggleMcpServer => {
+                self.commit_settings_focus();
                 self.editor_state
                     .editor_ui
                     .agent_settings