diff --git a/README.md b/README.md
index 9fe5a65..d9c885e 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,8 @@
 
 RuDS is a native Rust blogging desktop application and the successor to bDS2. It manages local projects from authoring through preview, static-site generation, integrity checks, and publishing while preserving the existing bDS filesystem and SQLite formats.
 
+The desktop is a single-window application: closing its window persists UI state and exits RuDS.
+
 The project is under active development. Core blogging workflows are broadly available; remaining core work and optional extensions are tracked separately.
 
 ## Available Features
diff --git a/crates/bds-ui/src/app.rs b/crates/bds-ui/src/app.rs
index f90fba3..3ef79b1 100644
--- a/crates/bds-ui/src/app.rs
+++ b/crates/bds-ui/src/app.rs
@@ -186,6 +186,7 @@ pub enum Message {
         task_id: TaskId,
         result: Result<engine::blogmark::BlogmarkImportResult, String>,
     },
+    WindowCloseRequested,
     MainWindowLoaded(Option<window::Id>),
     EmbeddedPreviewReady(Result<(), String>),
     EmbeddedStylePreviewReady(Result<(), String>),
@@ -1363,6 +1364,11 @@ impl BdsApp {
 
     pub fn update(&mut self, message: Message) -> Task<Message> {
         match message {
+            Message::WindowCloseRequested => {
+                self.persist_project_ui_state();
+                flush_embeddings_and_exit(std::process::exit)
+            }
+
             // ── Menu event dispatch ──
             Message::MenuEvent(id) => {
                 if let Some(action) = self.menu_registry.lookup(&id) {
@@ -3583,6 +3589,7 @@ impl BdsApp {
             }
             _ => None,
         });
+        let window_close_sub = window::close_requests().map(|_| Message::WindowCloseRequested);
 
         // Global mouse tracking for sidebar resize dragging.
         // The 4px drag handle mouse_area only fires on_press; move/release
@@ -3637,6 +3644,7 @@ impl BdsApp {
             domain_event_tick,
             toast_tick,
             file_drop_sub,
+            window_close_sub,
             drag_sub,
             menu_interaction_sub,
             menu_expand_tick,
@@ -10067,6 +10075,14 @@ impl Drop for BdsApp {
     }
 }
 
+fn flush_embeddings_and_exit<F, R>(exit: F) -> R
+where
+    F: FnOnce(i32) -> R,
+{
+    let _ = engine::embedding::EmbeddingService::flush_all();
+    exit(0)
+}
+
 fn content_sample(content: &str, max_len: usize) -> String {
     content.chars().take(max_len).collect()
 }
@@ -10125,12 +10141,12 @@ fn remote_error_closes_connection(code: &str) -> bool {
 mod tests {
     use super::{
         BdsApp, Message, POST_AUTO_SAVE_DELAY_MS, PersistedMediaState, PersistedPostState,
-        PostStatus, SettingsMsg, active_post_tab_id, dropped_image_target, localize_chat_error,
-        month_abbreviation, persist_media_editor_state_impl,
-        persist_post_editor_preview_state_impl, persist_post_editor_state_impl,
-        remote_error_closes_connection, save_editor_settings_state_impl,
-        save_script_editor_state_impl, save_template_editor_state_impl,
-        should_start_embedded_preview_creation,
+        PostStatus, SettingsMsg, active_post_tab_id, dropped_image_target,
+        flush_embeddings_and_exit, localize_chat_error, month_abbreviation,
+        persist_media_editor_state_impl, persist_post_editor_preview_state_impl,
+        persist_post_editor_state_impl, remote_error_closes_connection,
+        save_editor_settings_state_impl, save_script_editor_state_impl,
+        save_template_editor_state_impl, should_start_embedded_preview_creation,
     };
     use crate::i18n::t;
     use crate::platform::menu::MenuAction;
@@ -10160,6 +10176,7 @@ mod tests {
     use bds_core::model::{
         ChatRole, DomainEntity, DomainEvent, NotificationAction, Project, ScriptKind, TemplateKind,
     };
+
     use chrono::{Datelike, TimeZone};
     use std::io::{Read, Write};
     use std::net::TcpListener;
@@ -10167,6 +10184,13 @@ mod tests {
     use std::thread;
     use tempfile::TempDir;
 
+    #[test]
+    fn desktop_shutdown_uses_an_immediate_process_exit() {
+        let exit_code = flush_embeddings_and_exit(|code| code);
+
+        assert_eq!(exit_code, 0);
+    }
+
     fn make_project() -> Project {
         Project {
             id: "p1".to_string(),
diff --git a/crates/bds-ui/src/main.rs b/crates/bds-ui/src/main.rs
index dc656c1..ef33127 100644
--- a/crates/bds-ui/src/main.rs
+++ b/crates/bds-ui/src/main.rs
@@ -30,15 +30,20 @@ fn main() -> anyhow::Result<()> {
     iced::application("bDS", BdsApp::update, BdsApp::view)
         .subscription(BdsApp::subscription)
         .theme(|_| inputs::app_theme())
-        .window(iced::window::Settings {
-            size: iced::Size::new(1200.0, 800.0),
-            icon: Some(icon),
-            ..Default::default()
-        })
+        .window(desktop_window_settings(Some(icon)))
         .run_with(BdsApp::new)?;
     Ok(())
 }
 
+fn desktop_window_settings(icon: Option<iced::window::Icon>) -> iced::window::Settings {
+    iced::window::Settings {
+        size: iced::Size::new(1200.0, 800.0),
+        icon,
+        exit_on_close_request: false,
+        ..Default::default()
+    }
+}
+
 fn current_platform() -> Platform {
     #[cfg(target_os = "macos")]
     return Platform::MacOs;
@@ -49,3 +54,13 @@ fn current_platform() -> Platform {
     #[allow(unreachable_code)]
     Platform::Windows
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn single_window_close_is_owned_by_the_application() {
+        assert!(!desktop_window_settings(None).exit_on_close_request);
+    }
+}
diff --git a/specs/layout.allium b/specs/layout.allium
index affcf6b..6a2a448 100644
--- a/specs/layout.allium
+++ b/specs/layout.allium
@@ -19,6 +19,7 @@ surface LayoutControlSurface {
         TogglePanelRequested()
         ToggleAssistantSidebarRequested()
         ActivityClicked(activity_id)
+        CloseWindowRequested()
 }
 
 surface LayoutRuntimeSurface {
@@ -55,6 +56,13 @@ value AppShell {
     status_bar: StatusBar
 }
 
+rule CloseSingleWindow {
+    when: CloseWindowRequested()
+    ensures: ExitApplication()
+    -- bDS2 and RuDS are single-window applications. Closing that window
+    -- persists application-owned state and terminates the process.
+}
+
 surface AppShellSurface {
     context shell: AppShell