diff --git a/crates/tui/src/config.rs b/crates/tui/src/config.rs
index 04bc18e8c..05cb1b4e2 100644
--- a/crates/tui/src/config.rs
+++ b/crates/tui/src/config.rs
@@ -516,6 +516,19 @@ fn default_threshold_secs() -> u64 {
     30
 }
 
+/// Completion sound options.
+#[derive(Debug, Clone, Copy, Deserialize, Default, PartialEq, Eq)]
+#[serde(rename_all = "kebab-case")]
+pub enum CompletionSound {
+    /// No sound on turn completion.
+    Off,
+    /// System notification beep (default). On Windows uses `MessageBeep`.
+    #[default]
+    Beep,
+    /// Terminal BEL character (`\x07`).
+    Bell,
+}
+
 /// Desktop-notification configuration (OSC 9 / BEL on turn completion).
 #[derive(Debug, Clone, Deserialize, Default)]
 pub struct NotificationsConfig {
@@ -535,6 +548,11 @@ pub struct NotificationsConfig {
     /// Default: `false`.
     #[serde(default)]
     pub include_summary: bool,
+
+    /// Completion sound: `"off"` | `"beep"` | `"bell"`. Default: `"beep"`.
+    /// Plays a sound when every turn finishes (alongside the ✅ marker).
+    #[serde(default)]
+    pub completion_sound: CompletionSound,
 }
 
 fn default_snapshots_enabled() -> bool {
diff --git a/crates/tui/src/core/engine/turn_loop.rs b/crates/tui/src/core/engine/turn_loop.rs
index 1cfe8f097..3934aad51 100644
--- a/crates/tui/src/core/engine/turn_loop.rs
+++ b/crates/tui/src/core/engine/turn_loop.rs
@@ -20,6 +20,11 @@ impl Engine {
         mode: AppMode,
         force_update_plan_first: bool,
     ) -> (TurnOutcomeStatus, Option<String>) {
+        // Signal to the terminal / taskbar that a turn is in progress
+        // (OSC 9 ; 4 indeterminate progress + title spinner).
+        crate::tui::notifications::set_taskbar_progress_busy();
+        crate::tui::notifications::start_title_animation("DeepSeek TUI");
+
         let client = self
             .deepseek_client
             .clone()
diff --git a/crates/tui/src/tui/notifications.rs b/crates/tui/src/tui/notifications.rs
index fcfe4ba3e..d4276645e 100644
--- a/crates/tui/src/tui/notifications.rs
+++ b/crates/tui/src/tui/notifications.rs
@@ -17,6 +17,8 @@ use windows::Win32::System::Diagnostics::Debug::MessageBeep;
 use windows::Win32::UI::WindowsAndMessaging::MESSAGEBOX_STYLE;
 
 use std::io::{self, Write};
+use std::sync::atomic::AtomicU8;
+use std::sync::atomic::{AtomicBool, Ordering};
 use std::time::Duration;
 
 /// Notification delivery method.
@@ -207,6 +209,170 @@ pub fn notify_done(
     notify_done_to(method, in_tmux, msg, threshold, elapsed, &mut io::stdout());
 }
 
+/// Set the terminal taskbar progress state via OSC 9 ; 4.
+///
+/// Windows Terminal supports this to show progress on the taskbar icon:
+/// - `state = 0` — no progress (clear)
+/// - `state = 1` — indeterminate (cycling green)
+/// - `state = 2` — normal (0-100, requires progress param)
+/// - `state = 3` — error (red)
+/// - `state = 4` — paused (yellow)
+///
+/// Other terminals (iTerm2, WezTerm) ignore the sequence silently.
+/// Best-effort — write failures are ignored.
+pub fn set_taskbar_progress(state: u8, progress: Option<u8>) {
+    let seq = if let Some(pct) = progress {
+        format!("\x1b]9;4;{state};{pct}\x07")
+    } else {
+        format!("\x1b]9;4;{state}\x07")
+    };
+    let mut stdout = io::stdout();
+    let _ = stdout.write_all(seq.as_bytes());
+    let _ = stdout.flush();
+}
+
+/// Set taskbar progress to indeterminate (cycling) — call at turn start.
+pub fn set_taskbar_progress_busy() {
+    set_taskbar_progress(1, None);
+}
+
+/// Clear taskbar progress — call at turn end.
+pub fn clear_taskbar_progress() {
+    set_taskbar_progress(0, None);
+}
+
+/// Animation frame characters for the terminal title.
+/// Uses the DeepSeek whale emoji (🐳 spouting, 🐋 resting) to match the
+/// existing header status indicator in the TUI.
+const TITLE_FRAMES: &[&str] = &["🐳", "🐋", "🐳", "🐋"];
+const TITLE_ANIMATION_INTERVAL: Duration = Duration::from_millis(800);
+
+/// Shared flag controlling the title animation loop. Set to `true` by
+/// `start_title_animation()`, cleared by `stop_title_animation()`.
+static TITLE_ANIMATION_RUNNING: AtomicBool = AtomicBool::new(false);
+
+/// Write OSC 0 (set window title) sequence.
+fn set_terminal_title(title: &str) {
+    let seq = format!("\x1b]0;{title}\x07");
+    let mut stdout = io::stdout();
+    let _ = stdout.write_all(seq.as_bytes());
+    let _ = stdout.flush();
+}
+
+/// Tracks whether the ✅ completion marker was set, so
+/// `reset_title_on_interaction()` can skip redundant writes.
+static COMPLETION_MARKER_SHOWN: AtomicBool = AtomicBool::new(false);
+
+/// Start an animated terminal title spinner.
+///
+/// Cycles the terminal title between 🐳→🐋 every 800ms while processing,
+/// matching the whale status indicator in the TUI header, so alt-tabbed
+/// users can see activity.
+///
+/// The animation runs in a background tokio task that checks
+/// `TITLE_ANIMATION_RUNNING`. Each call restarts the animation with the
+/// given `original` base title — safe to call on every turn start.
+pub fn start_title_animation(original: &str) {
+    // Signal any existing animation loop to exit, then start fresh.
+    TITLE_ANIMATION_RUNNING.store(true, Ordering::SeqCst);
+    let base = original.to_string();
+    tokio::spawn(async move {
+        let mut frame = 0usize;
+        while TITLE_ANIMATION_RUNNING.load(Ordering::SeqCst) {
+            // Yield once per frame so a racing stop_title_animation()
+            // can observe the cleared flag and apply the completion
+            // marker before the next frame write. Without this yield
+            // the background task could overwrite the ✅ marker with
+            // the next whale frame.
+            tokio::task::yield_now().await;
+            if !TITLE_ANIMATION_RUNNING.load(Ordering::SeqCst) {
+                break;
+            }
+            let spinner = TITLE_FRAMES[frame % TITLE_FRAMES.len()];
+            set_terminal_title(&format!("{spinner} {base}"));
+            frame += 1;
+            tokio::time::sleep(TITLE_ANIMATION_INTERVAL).await;
+        }
+        // Don't restore title here — stop_title_animation() handles
+        // what to show on completion (e.g. ✅ marker).
+    });
+}
+
+/// Stop the title animation and show a completion marker.
+///
+/// Sets the title to `✅ <base>` so alt-tabbed users see at a glance
+/// that processing finished. The marker is overwritten on the next turn
+/// by [`start_title_animation`].
+pub fn stop_title_animation() {
+    TITLE_ANIMATION_RUNNING.store(false, Ordering::SeqCst);
+    COMPLETION_MARKER_SHOWN.store(false, Ordering::SeqCst);
+    // Show ✅ marker only for beep mode. Bell mode already has its own
+    // terminal-level visual indicator (flash/icon).
+    let mode = COMPLETION_SOUND_MODE.load(Ordering::SeqCst);
+    if mode == 1 {
+        set_terminal_title("✅ DeepSeek TUI");
+    }
+    play_completion_sound();
+}
+
+/// Clear the ✅ completion marker from the title when the user interacts.
+///
+/// Call this on every user input event (key press, mouse click) so the
+/// marker doesn't persist once the user is back at the terminal.
+pub fn reset_title_on_interaction() {
+    if COMPLETION_MARKER_SHOWN.swap(false, Ordering::SeqCst) {
+        set_terminal_title("DeepSeek TUI");
+    }
+}
+
+/// Completion sound mode (0 = off, 1 = beep, 2 = bell).
+static COMPLETION_SOUND_MODE: AtomicU8 = AtomicU8::new(1);
+
+/// Set the completion sound mode from config.
+/// Call once at startup or on `/settings` change.
+pub fn set_completion_sound_mode(mode: crate::config::CompletionSound) {
+    let val = match mode {
+        crate::config::CompletionSound::Off => 0u8,
+        crate::config::CompletionSound::Beep => 1u8,
+        crate::config::CompletionSound::Bell => 2u8,
+    };
+    COMPLETION_SOUND_MODE.store(val, Ordering::SeqCst);
+}
+
+/// Play the configured completion sound (if not `Off`).
+pub fn play_completion_sound() {
+    match COMPLETION_SOUND_MODE.load(Ordering::SeqCst) {
+        0 => {} // Off
+        1 => {
+            beep_sound();
+        }
+        2 => {
+            bell_sound();
+        }
+        _ => {}
+    }
+}
+
+/// Play a short completion sound via the system beep.
+///
+/// On Windows uses `MessageBeep(MB_OK)` which plays the default system
+/// notification sound. On other platforms writes `BEL` (`\x07`) to stdout.
+#[cfg(target_os = "windows")]
+fn beep_sound() {
+    windows_bell();
+}
+
+/// Non-Windows: write BEL to stdout for the terminal bell.
+#[cfg(not(target_os = "windows"))]
+fn beep_sound() {
+    let _ = io::stdout().write_all(b"\x07");
+}
+
+/// Pure terminal BEL character.
+fn bell_sound() {
+    let _ = io::stdout().write_all(b"\x07");
+}
+
 /// Return a human-readable duration string, capped at two units so
 /// it stays compact in headers and notifications.
 ///
@@ -289,6 +455,8 @@ use crate::tui::app::App;
 /// `Off`).
 pub fn settings(config: &crate::config::Config) -> Option<(Method, Duration, bool)> {
     let notif = config.notifications_config();
+    // Initialize completion sound mode from config.
+    set_completion_sound_mode(notif.completion_sound);
     let method = match notif.method {
         crate::config::NotificationMethod::Auto => Method::Auto,
         crate::config::NotificationMethod::Osc9 => Method::Osc9,
diff --git a/crates/tui/src/tui/ui.rs b/crates/tui/src/tui/ui.rs
index 3cf028a40..247566b01 100644
--- a/crates/tui/src/tui/ui.rs
+++ b/crates/tui/src/tui/ui.rs
@@ -1422,6 +1422,8 @@ async fn run_event_loop(
                                 threshold,
                                 turn_elapsed,
                             );
+                            crate::tui::notifications::clear_taskbar_progress();
+                            crate::tui::notifications::stop_title_animation();
                         }
 
                         // Auto-save completed turn and clear crash checkpoint.
@@ -2194,6 +2196,8 @@ async fn run_event_loop(
             if app.use_mouse_capture
                 && let Event::Mouse(mouse) = evt
             {
+                // Mouse interaction clears the ✅ completion marker.
+                crate::tui::notifications::reset_title_on_interaction();
                 if should_drop_loading_mouse_motion(app, mouse) {
                     continue;
                 }
@@ -2214,6 +2218,9 @@ async fn run_event_loop(
                 continue;
             }
 
+            // User interaction — clear the ✅ completion marker from the title.
+            crate::tui::notifications::reset_title_on_interaction();
+
             let Event::Key(key) = evt else {
                 continue;
             };
diff --git a/crates/tui/src/tui/ui/tests.rs b/crates/tui/src/tui/ui/tests.rs
index 5ec4f7883..25d81424a 100644
--- a/crates/tui/src/tui/ui/tests.rs
+++ b/crates/tui/src/tui/ui/tests.rs
@@ -5841,6 +5841,7 @@ fn notification_settings_tui_always_keeps_configured_method_no_threshold() {
         notifications: Some(crate::config::NotificationsConfig {
             method: crate::config::NotificationMethod::Bel,
             threshold_secs: 120,
+            completion_sound: crate::config::CompletionSound::Beep,
             include_summary: true,
         }),
         ..Config::default()
@@ -5872,6 +5873,7 @@ fn notification_settings_no_tui_override_uses_notifications_block() {
         notifications: Some(crate::config::NotificationsConfig {
             method: crate::config::NotificationMethod::Osc9,
             threshold_secs: 45,
+            completion_sound: crate::config::CompletionSound::Beep,
             include_summary: false,
         }),
         ..Config::default()