refactor: render the shell in the client (#3487)

* feat: add opt-in client-rendered shell

* feat: add client-owned shell mouse controls

* feat: complete client-owned shell chrome

* feat: add client-owned shell settings and notifications

* feat: run client shell custom commands

* feat: render popup terminals in client shell

* feat: add client-owned scrollback and copy mode

* fix: preserve client worktree trust defaults

* feat: render startup diagnostics in client shell

* feat: render onboarding in client shell

* feat: render product announcements in client shell

* feat: render release notes in client shell

* feat: render mobile switcher in client shell

* feat: render kitty graphics in client shell

* fix: preserve client shell lifecycle coherence

* refactor: route client shell commands through endpoint connections

* refactor: make the client-rendered shell the default

* refactor: remove monolithic launch mode

* refactor: complete client-rendered shell cutover

* perf: retain client pane surface updates

* perf: scale retained pane surface updates

* perf: remove remote pane input latency

* test: make client shell checks platform-independent

* fix: prevent client timer starvation

* test: fix client shell platform gates

* test: accept retained surfaces in cross-area checks

* test: make client mode assertions platform-neutral

* fix: badge only outdated integrations

1 files changed, 5025 insertions, 0 deletions

diff --git a/src/server/headless/tests/mod.rs b/src/server/headless/tests/mod.rs
new file mode 100644
index 00000000..102f2fc6
--- /dev/null
+++ b/src/server/headless/tests/mod.rs
@@ -0,0 +1,5025 @@
+use super::*;
+
+#[path = "pane_graphics.rs"]
+mod pane_graphics_tests;
+
+fn test_headless_server() -> HeadlessServer {
+    test_headless_server_with_event_hub(api::EventHub::default())
+}
+
+fn test_headless_server_with_event_hub(event_hub: api::EventHub) -> HeadlessServer {
+    let config = crate::config::Config::default();
+    let (_api_tx, api_rx) = tokio::sync::mpsc::unbounded_channel();
+    let app = crate::app::App::new(
+        &config,
+        crate::app::AppPolicy::TEST,
+        None,
+        api_rx,
+        event_hub,
+    );
+
+    let dir = std::env::temp_dir().join(format!(
+        "hh-{}-{}",
+        std::process::id(),
+        std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .map(|d| d.as_nanos())
+            .unwrap_or(0)
+    ));
+    let _ = fs::create_dir_all(&dir);
+    let socket_path = dir.join("client.sock");
+    let _ = fs::remove_file(&socket_path);
+    let listener = bind_local_listener(&socket_path).expect("bind test listener");
+    let client_socket_identity =
+        socket_file_identity(&socket_path).expect("test listener socket identity");
+    #[cfg(unix)]
+    listener
+        .set_nonblocking(ListenerNonblockingMode::Accept)
+        .expect("set listener nonblocking");
+    let (server_event_tx, server_event_rx) = mpsc::channel(64);
+    let should_quit = Arc::new(AtomicBool::new(false));
+    #[cfg(windows)]
+    spawn_windows_client_accept_thread(listener, should_quit.clone(), server_event_tx.clone());
+    let server_keybindings = app_keybindings(&app);
+    let headless_size = app.state.headless_size;
+
+    HeadlessServer {
+        app,
+        #[cfg(unix)]
+        api_tx: None,
+        api_server: None,
+        #[cfg(unix)]
+        client_listener: listener,
+        client_socket_path: socket_path,
+        client_socket_identity,
+        clients: HashMap::new(),
+        #[cfg(unix)]
+        next_client_id: 1,
+        foreground_client_id: None,
+        client_shell_boot_id: "test-boot".into(),
+        sent_window_title: None,
+        api_window_title: None,
+        server_keybindings,
+        server_config_diagnostic: None,
+        server_config_diagnostic_without_keybindings: None,
+        terminal_attach_owners: HashMap::new(),
+        pending_alt_screen_reads: Vec::new(),
+        deferred_alt_screen_reads: Vec::new(),
+        next_activity_stamp: 1,
+        headless_size,
+        effective_size: headless_size,
+        shutting_down: false,
+        handoff_in_progress: false,
+        #[cfg(unix)]
+        pending_handoff_repaint_nudge: false,
+        should_quit,
+        server_event_rx,
+        server_event_tx,
+    }
+}
+
+fn shutdown_test_runtimes(server: &mut HeadlessServer) {
+    for (_, runtime) in server.app.terminal_runtimes.drain() {
+        runtime.shutdown();
+    }
+}
+
+fn read_server_message(bytes: Vec<u8>) -> ServerMessage {
+    let mut cursor = std::io::Cursor::new(bytes);
+    protocol::read_message(&mut cursor, MAX_FRAME_SIZE).expect("decode server message")
+}
+
+fn frame_text(frame: &FrameData) -> String {
+    frame
+        .cells
+        .chunks(usize::from(frame.width))
+        .map(|row| {
+            row.iter()
+                .map(|cell| cell.symbol.as_str())
+                .collect::<String>()
+        })
+        .collect::<Vec<_>>()
+        .join("\n")
+}
+
+fn read_server_shutdown_reason(bytes: Vec<u8>) -> Option<String> {
+    match read_server_message(bytes) {
+        ServerMessage::ServerShutdown { reason } => reason,
+        other => panic!("expected shutdown, got {other:?}"),
+    }
+}
+
+#[test]
+fn completed_handoff_disables_only_old_server_session_persistence() {
+    let mut server = test_headless_server();
+    server.app.policy = crate::app::AppPolicy::PRODUCTION;
+
+    server.finish_live_handoff_shutdown();
+
+    assert!(!server.app.policy.persist_session);
+    assert!(server.app.policy.restore_session);
+    assert!(server.app.policy.persist_plugin_registry);
+    assert!(server.app.policy.background_updates);
+}
+
+#[test]
+fn default_headless_size_is_effective_without_clients() {
+    let server = test_headless_server();
+
+    assert_eq!(
+        server.headless_size,
+        (
+            crate::config::DEFAULT_HEADLESS_COLS,
+            crate::config::DEFAULT_HEADLESS_ROWS
+        )
+    );
+    assert_eq!(server.effective_size, server.headless_size);
+}
+
+#[tokio::test]
+async fn headless_api_reads_latest_title_without_spinner_event_flooding() {
+    let event_hub = api::EventHub::default();
+    let mut server = test_headless_server_with_event_hub(event_hub.clone());
+    server.app.state.workspaces = vec![crate::workspace::Workspace::test_new("one")];
+    server.app.state.ensure_test_terminals();
+    server.app.state.active = Some(0);
+    server.app.state.selected = 0;
+    server.app.state.mode = crate::app::Mode::Terminal;
+    server.app.state.sidebar_agents.rows = vec![vec![
+        crate::config::AgentSidebarToken::TerminalTitleStripped,
+    ]];
+    let pane_id = server.app.state.workspaces[0].tabs[0].root_pane;
+    let terminal_id = server.app.state.workspaces[0].tabs[0].panes[&pane_id]
+        .attached_terminal_id
+        .clone();
+    server
+        .app
+        .state
+        .terminals
+        .get_mut(&terminal_id)
+        .unwrap()
+        .detected_agent = Some(crate::detect::Agent::Claude);
+    let runtime = crate::terminal::TerminalRuntime::test_with_screen_bytes(80, 24, b"");
+    runtime.test_process_pty_bytes(b"\x1b]0;\xe2\xa0\x8b task\x07");
+    server
+        .app
+        .terminal_runtimes
+        .insert(terminal_id.clone(), runtime);
+    server.app.render_dirty.request_terminal_title(pane_id);
+
+    let first = headless_pane_list(&mut server).pop().unwrap();
+    assert_eq!(first.terminal_title.as_deref(), Some("⠋ task"));
+    assert_eq!(first.terminal_title_stripped.as_deref(), Some("task"));
+    assert_eq!(pane_updated_events(&event_hub), 1);
+    server
+        .app
+        .terminal_runtimes
+        .get(&terminal_id)
+        .unwrap()
+        .test_process_pty_bytes(b"\x1b]2;\xe2\xa0\x99 task\x1b\\");
+    server.app.render_dirty.request_terminal_title(pane_id);
+    let second = headless_pane_list(&mut server).pop().unwrap();
+    assert_eq!(second.terminal_title.as_deref(), Some("⠙ task"));
+    assert_eq!(second.terminal_title_stripped.as_deref(), Some("task"));
+    assert_eq!(pane_updated_events(&event_hub), 1);
+}
+
+fn headless_pane_list(server: &mut HeadlessServer) -> Vec<api::schema::PaneInfo> {
+    let (respond_to, response_rx) = std::sync::mpsc::channel();
+    server.handle_api_request_with_shutdown_check(api::ApiRequestMessage {
+        request: api::schema::Request {
+            id: "list-titles".into(),
+            method: api::schema::Method::PaneList(api::schema::PaneListParams::default()),
+        },
+        respond_to,
+        response_write_complete: None,
+        stream_active: None,
+    });
+    let response: api::schema::SuccessResponse =
+        serde_json::from_str(&response_rx.recv().unwrap()).unwrap();
+    let api::schema::ResponseResult::PaneList { panes } = response.result else {
+        panic!("expected pane list");
+    };
+    panes
+}
+
+fn pane_updated_events(event_hub: &api::EventHub) -> usize {
+    event_hub
+        .events_after(0)
+        .iter()
+        .filter(|(_, event)| event.event == api::schema::EventKind::PaneUpdated)
+        .count()
+}
+
+#[test]
+fn server_stop_interrupts_server_event_backlog() {
+    let mut server = test_headless_server();
+    for client_id in 1..=64 {
+        server
+            .server_event_tx
+            .try_send(ServerEvent::ClientDisconnected { client_id })
+            .unwrap();
+    }
+
+    server.should_quit.store(true, Ordering::Release);
+
+    assert!(!server.drain_server_events());
+    assert!(server.server_event_rx.try_recv().is_ok());
+    shutdown_test_runtimes(&mut server);
+}
+
+#[test]
+fn headless_api_request_drains_all_pending_internal_events_before_reading_state() {
+    let mut server = test_headless_server();
+    for i in 0..=crate::app::APP_EVENT_DRAIN_LIMIT {
+        server
+            .app
+            .event_tx
+            .try_send(AppEvent::UpdateReady {
+                version: format!("4.0.{i}"),
+                install_command: "herdr install".into(),
+            })
+            .unwrap();
+    }
+
+    let (respond_to, response_rx) = std::sync::mpsc::channel();
+    assert!(
+        server.handle_api_request_with_shutdown_check(api::ApiRequestMessage {
+            request: api::schema::Request {
+                id: "headless_stop_after_events".into(),
+                method: api::schema::Method::ServerStop(api::schema::EmptyParams::default()),
+            },
+            respond_to,
+            response_write_complete: None,
+            stream_active: None,
+        })
+    );
+    let response = response_rx
+        .recv_timeout(Duration::from_millis(100))
+        .unwrap();
+    let response: serde_json::Value = serde_json::from_str(&response).unwrap();
+
+    assert_eq!(response["result"]["type"], "ok");
+    let expected_version = format!("4.0.{}", crate::app::APP_EVENT_DRAIN_LIMIT);
+    assert_eq!(
+        server.app.state.update_available.as_deref(),
+        Some(expected_version.as_str())
+    );
+    assert!(server.app.event_rx.try_recv().is_err());
+}
+
+fn window_title_test_server() -> (HeadlessServer, std::sync::mpsc::Receiver<Vec<u8>>) {
+    let mut server = test_headless_server();
+    server.app.state.workspaces = vec![crate::workspace::Workspace::test_new("herd")];
+    server.app.state.active = Some(0);
+    server.app.state.selected = 0;
+
+    let (client_tx, control_rx, _render_rx) = test_client_writer();
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            Some(client_tx),
+        ),
+    );
+    server.promote_client_to_foreground(1);
+    drain_window_titles(&control_rx);
+    (server, control_rx)
+}
+
+/// The test client writer drains its queue on a background thread, so
+/// reading a pushed message needs a timeout rather than `try_recv`.
+fn next_window_title(control_rx: &std::sync::mpsc::Receiver<Vec<u8>>) -> Option<Option<String>> {
+    let deadline = Instant::now() + Duration::from_secs(5);
+    while let Some(remaining) = deadline.checked_duration_since(Instant::now()) {
+        let Ok(bytes) = control_rx.recv_timeout(remaining) else {
+            return None;
+        };
+        if let ServerMessage::WindowTitle { title } = read_server_message(bytes) {
+            return Some(title);
+        }
+    }
+    None
+}
+
+fn drain_window_titles(control_rx: &std::sync::mpsc::Receiver<Vec<u8>>) {
+    while control_rx.recv_timeout(Duration::from_millis(50)).is_ok() {}
+}
+
+fn no_window_title(control_rx: &std::sync::mpsc::Receiver<Vec<u8>>) -> bool {
+    while let Ok(bytes) = control_rx.recv_timeout(Duration::from_millis(200)) {
+        if let ServerMessage::WindowTitle { .. } = read_server_message(bytes) {
+            return false;
+        }
+    }
+    true
+}
+
+#[test]
+fn window_title_waits_for_a_foreground_client_to_exist() {
+    let mut server = test_headless_server();
+    server.app.state.workspaces = vec![crate::workspace::Workspace::test_new("herd")];
+    server.app.state.active = Some(0);
+    server.app.configure_window_title("{workspace}");
+
+    // The server renders before the first client attaches. Nothing was
+    // delivered, so nothing may be recorded as delivered either.
+    server.sync_window_title();
+    assert_eq!(server.sent_window_title, None);
+
+    let (client_tx, control_rx, _render_rx) = test_client_writer();
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            Some(client_tx),
+        ),
+    );
+    server.promote_client_to_foreground(1);
+    server.sync_window_title();
+
+    assert_eq!(
+        next_window_title(&control_rx),
+        Some(Some("herd".to_string()))
+    );
+    shutdown_test_runtimes(&mut server);
+}
+
+#[test]
+fn an_attaching_client_gets_the_title_even_when_it_has_not_changed() {
+    let (mut server, first_control_rx) = window_title_test_server();
+    server.app.configure_window_title("{workspace}");
+    server.sync_window_title();
+    assert_eq!(
+        next_window_title(&first_control_rx),
+        Some(Some("herd".to_string()))
+    );
+
+    // ClientConnected assigns the foreground client directly rather than
+    // going through promote_client_to_foreground, so the cache must notice
+    // the new client on its own.
+    let (client_tx, second_control_rx, _render_rx) = test_client_writer();
+    server.clients.insert(
+        2,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            2,
+            RenderEncoding::SemanticFrame,
+            Some(client_tx),
+        ),
+    );
+    server.foreground_client_id = Some(2);
+    server.sync_window_title();
+
+    assert_eq!(
+        next_window_title(&second_control_rx),
+        Some(Some("herd".to_string()))
+    );
+    shutdown_test_runtimes(&mut server);
+}
+
+#[test]
+fn configured_window_title_reaches_the_foreground_client_once_per_change() {
+    let (mut server, control_rx) = window_title_test_server();
+    server.app.configure_window_title("{workspace}/{tab}");
+
+    server.sync_window_title();
+    assert_eq!(
+        next_window_title(&control_rx),
+        Some(Some("herd/1".to_string()))
+    );
+
+    // An unchanged title must not re-emit an OSC on every render.
+    server.sync_window_title();
+    assert!(no_window_title(&control_rx));
+
+    server.app.state.workspaces[0].tabs[0].custom_name = Some("build".into());
+    server.sync_window_title();
+    assert_eq!(
+        next_window_title(&control_rx),
+        Some(Some("herd/build".to_string()))
+    );
+
+    shutdown_test_runtimes(&mut server);
+}
+
+#[tokio::test]
+async fn focused_terminal_title_syncs_without_requesting_a_sidebar_render() {
+    let (mut server, control_rx) = window_title_test_server();
+    server.app.configure_window_title("{terminal_title}");
+    server.app.state.ensure_test_terminals();
+    let pane_id = server.app.state.workspaces[0].tabs[0].root_pane;
+    let terminal_id = server.app.state.workspaces[0]
+        .terminal_id(pane_id)
+        .expect("terminal")
+        .clone();
+    let runtime = crate::terminal::TerminalRuntime::test_with_screen_bytes(80, 24, b"");
+    runtime.test_process_pty_bytes("\x1b]0;⠋ building\x07".as_bytes());
+    server
+        .app
+        .terminal_runtimes
+        .insert(terminal_id.clone(), runtime);
+
+    assert_eq!(
+        server.sync_terminal_title_sources(&HashSet::from([pane_id])),
+        (false, true)
+    );
+    assert_eq!(
+        next_window_title(&control_rx),
+        Some(Some("building".to_string()))
+    );
+
+    server
+        .app
+        .terminal_runtimes
+        .get(&terminal_id)
+        .expect("runtime")
+        .test_process_pty_bytes("\x1b]0;⠙ building\x07".as_bytes());
+    assert_eq!(
+        server.sync_terminal_title_sources(&HashSet::from([pane_id])),
+        (false, true)
+    );
+    assert!(no_window_title(&control_rx));
+
+    shutdown_test_runtimes(&mut server);
+}
+
+#[test]
+fn a_foreground_client_without_a_writer_does_not_cache_the_window_title() {
+    let (mut server, _control_rx) = window_title_test_server();
+    server.app.configure_window_title("{workspace}");
+
+    // A detached client keeps its entry but loses its writer, so nothing
+    // reaches a terminal even though the targeted send reports success.
+    if let Some(client) = server.clients.get_mut(&1) {
+        client.writer = None;
+    }
+    server.sync_window_title();
+    assert!(server.sent_window_title.is_none());
+
+    // Attaching again has to deliver the title rather than skip it as sent.
+    let (client_tx, control_rx, _render_rx) = test_client_writer();
+    if let Some(client) = server.clients.get_mut(&1) {
+        client.writer = Some(client_tx);
+    }
+    server.sync_window_title();
+    assert_eq!(
+        next_window_title(&control_rx),
+        Some(Some("herd".to_string()))
+    );
+
+    shutdown_test_runtimes(&mut server);
+}
+
+#[test]
+fn empty_window_title_config_leaves_the_outer_title_alone() {
+    let (mut server, control_rx) = window_title_test_server();
+    server.app.configure_window_title("");
+
+    server.sync_window_title();
+
+    assert!(no_window_title(&control_rx));
+    shutdown_test_runtimes(&mut server);
+}
+
+#[test]
+fn api_window_title_wins_until_it_is_cleared() {
+    let (mut server, control_rx) = window_title_test_server();
+    server.app.configure_window_title("{workspace}");
+
+    server.handle_client_window_title_api("set".into(), Some("herdr api".into()));
+    assert_eq!(
+        next_window_title(&control_rx),
+        Some(Some("herdr api".to_string()))
+    );
+
+    server.app.state.workspaces[0].custom_name = Some("ops".into());
+    server.sync_window_title();
+    assert!(no_window_title(&control_rx));
+
+    // Clearing hands the title back to ui.window_title, not to "herdr".
+    server.handle_client_window_title_api("clear".into(), None);
+    assert_eq!(
+        next_window_title(&control_rx),
+        Some(Some("ops".to_string()))
+    );
+
+    shutdown_test_runtimes(&mut server);
+}
+
+#[test]
+fn clearing_the_api_title_falls_back_to_herdr_when_window_titles_are_disabled() {
+    let (mut server, control_rx) = window_title_test_server();
+    server.app.configure_window_title("");
+
+    server.handle_client_window_title_api("set".into(), Some("herdr api".into()));
+    assert_eq!(
+        next_window_title(&control_rx),
+        Some(Some("herdr api".to_string()))
+    );
+
+    server.handle_client_window_title_api("clear".into(), None);
+    assert_eq!(next_window_title(&control_rx), Some(None));
+
+    shutdown_test_runtimes(&mut server);
+}
+
+#[test]
+fn a_newly_promoted_client_gets_the_window_title_again() {
+    let (mut server, first_control_rx) = window_title_test_server();
+    server.app.configure_window_title("{workspace}");
+    server.sync_window_title();
+    assert_eq!(
+        next_window_title(&first_control_rx),
+        Some(Some("herd".to_string()))
+    );
+
+    // A second terminal starts on whatever its shell or ssh left behind.
+    let (client_tx, second_control_rx, _render_rx) = test_client_writer();
+    server.clients.insert(
+        2,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            2,
+            RenderEncoding::SemanticFrame,
+            Some(client_tx),
+        ),
+    );
+    server.promote_client_to_foreground(2);
+    server.sync_window_title();
+
+    assert_eq!(
+        next_window_title(&second_control_rx),
+        Some(Some("herd".to_string()))
+    );
+    shutdown_test_runtimes(&mut server);
+}
+
+fn test_client_writer() -> (
+    ClientWriter,
+    std::sync::mpsc::Receiver<Vec<u8>>,
+    std::sync::mpsc::Receiver<Vec<u8>>,
+) {
+    let (control_tx, control_rx) = std::sync::mpsc::channel();
+    let (render_tx, render_rx) = std::sync::mpsc::sync_channel(1);
+    (
+        ClientWriter::test_channel(control_tx, render_tx),
+        control_rx,
+        render_rx,
+    )
+}
+
+#[tokio::test]
+async fn client_shell_attach_seeds_workspace() {
+    let mut server = test_headless_server();
+    server.app.state.workspaces.clear();
+    server.app.state.active = None;
+    server.app.state.mode = crate::app::Mode::Navigate;
+    let (writer, _control_rx, _render_rx) = test_client_writer();
+
+    assert!(
+        server.handle_server_event(ServerEvent::ClientShellConnected {
+            client_id: 6,
+            surface_cols: 80,
+            surface_rows: 23,
+            cell_width_px: 0,
+            cell_height_px: 0,
+            pixel_mouse: false,
+            direct_graphics: false,
+            endpoint_keybindings: false,
+            mouse_capture: false,
+            writer,
+        })
+    );
+
+    assert_eq!(server.app.state.mode, crate::app::Mode::Terminal);
+    assert_eq!(server.app.state.workspaces.len(), 1);
+    assert_eq!(server.app.state.active, Some(0));
+    shutdown_test_runtimes(&mut server);
+}
+
+#[tokio::test]
+async fn client_shell_endpoint_request_uses_the_selected_connection() {
+    let mut server = test_headless_server();
+    let (writer, control_rx, _render_rx) = test_client_writer();
+    let client_id = 41;
+    assert!(
+        server.handle_server_event(ServerEvent::ClientShellConnected {
+            client_id,
+            surface_cols: 80,
+            surface_rows: 23,
+            cell_width_px: 0,
+            cell_height_px: 0,
+            pixel_mouse: false,
+            direct_graphics: false,
+            endpoint_keybindings: false,
+            mouse_capture: false,
+            writer,
+        })
+    );
+    let _initial_snapshot = control_rx.recv().expect("initial shell snapshot");
+    let boot_id = server.client_shell_boot_id.clone();
+
+    assert!(
+        !server.handle_server_event(ServerEvent::ClientShellEndpointRequest {
+            client_id,
+            boot_id: boot_id.clone(),
+            request: Box::new(api::schema::Request {
+                id: "client-shell:1".into(),
+                method: api::schema::Method::IntegrationList(api::schema::EmptyParams::default(),),
+            }),
+        })
+    );
+    assert!(server.clients[&client_id].shell_endpoint_command_in_flight);
+
+    let response_ready = server
+        .server_event_rx
+        .recv()
+        .await
+        .expect("endpoint response ready");
+    assert!(!server.handle_server_event(response_ready));
+    assert!(!server.clients[&client_id].shell_endpoint_command_in_flight);
+
+    match read_server_message(control_rx.recv().expect("endpoint response")) {
+        ServerMessage::ClientShellEndpointResponseChunk {
+            boot_id: response_boot_id,
+            request_id,
+            final_chunk,
+            data,
+        } => {
+            assert_eq!(response_boot_id, boot_id);
+            assert_eq!(request_id, "client-shell:1");
+            assert!(final_chunk);
+            let response = serde_json::from_slice::<api::schema::SuccessResponse>(&data)
+                .expect("success response");
+            assert_eq!(response.id, "client-shell:1");
+            assert!(matches!(
+                response.result,
+                api::schema::ResponseResult::IntegrationList { .. }
+            ));
+        }
+        other => panic!("expected client shell endpoint response, got {other:?}"),
+    }
+    shutdown_test_runtimes(&mut server);
+}
+
+#[tokio::test]
+async fn client_shell_receives_metadata_then_shell_free_pane_surface() {
+    let mut server = test_headless_server();
+    let mut workspace = crate::workspace::Workspace::test_new("shell-only-label");
+    let pane_id = workspace.focused_pane_id().expect("focused pane");
+    workspace.insert_test_runtime(
+        pane_id,
+        crate::terminal::TerminalRuntime::test_with_screen_bytes(
+            80,
+            23,
+            b"\x1b[?1003h\x1b[?1006h\x1b[?1016hCLIENT_SHELL_LIVE",
+        ),
+    );
+    server.app.state.workspaces = vec![workspace];
+    server.app.state.active = Some(0);
+    server.app.state.selected = 0;
+    server.app.state.mode = crate::app::Mode::Terminal;
+    server.app.state.product_announcement = Some(crate::app::state::ProductAnnouncementState {
+        version: "0.8.2".into(),
+        id: "client-shell".into(),
+        title: "Client shell".into(),
+        body: "announcement".into(),
+        scroll: 0,
+        preview: true,
+    });
+    server.server_config_diagnostic_without_keybindings = Some("endpoint config warning".into());
+
+    let (writer, control_rx, render_rx) = test_client_writer();
+    assert!(
+        server.handle_server_event(ServerEvent::ClientShellConnected {
+            client_id: 7,
+            surface_cols: 80,
+            surface_rows: 23,
+            cell_width_px: 10,
+            cell_height_px: 20,
+            pixel_mouse: true,
+            direct_graphics: false,
+            endpoint_keybindings: false,
+            mouse_capture: false,
+            writer,
+        })
+    );
+    match read_server_message(control_rx.recv().expect("shell snapshot")) {
+        ServerMessage::ClientShellSnapshot(snapshot) => {
+            assert_eq!(snapshot.workspaces.len(), 1);
+            assert_eq!(snapshot.workspaces[0].label, "shell-only-label");
+            assert_eq!(
+                snapshot.config_diagnostic.as_deref(),
+                Some("endpoint config warning")
+            );
+            assert_eq!(
+                snapshot.product_announcement.as_ref().map(|announcement| (
+                    announcement.version.as_str(),
+                    announcement.id.as_str(),
+                    announcement.preview,
+                )),
+                Some(("0.8.2", "client-shell", true))
+            );
+        }
+        other => panic!("expected client shell snapshot, got {other:?}"),
+    }
+
+    server.render_and_stream();
+    let initial_surface = match read_server_message(render_rx.recv().expect("pane surface")) {
+        ServerMessage::PaneSurface(surface) => {
+            assert_eq!((surface.frame.width, surface.frame.height), (80, 23));
+            let text = frame_text(&surface.frame);
+            assert!(text.contains("CLIENT_SHELL_LIVE"), "surface: {text:?}");
+            assert!(!text.contains("shell-only-label"), "surface: {text:?}");
+            assert_eq!(surface.panes.len(), 1);
+            assert_eq!(surface.panes[0].rect.x, 0);
+            assert_eq!(surface.panes[0].rect.y, 0);
+            assert!(surface.panes[0].sgr_pixel_mouse);
+            assert_eq!(
+                surface.panes[0].pixel_width,
+                u32::from(surface.panes[0].inner_rect.width) * 10
+            );
+            assert_eq!(
+                surface.panes[0].pixel_height,
+                u32::from(surface.panes[0].inner_rect.height) * 20
+            );
+            surface
+        }
+        other => panic!("expected pane surface, got {other:?}"),
+    };
+
+    server
+        .app
+        .state
+        .runtime_for_pane_in_workspace(&server.app.terminal_runtimes, 0, pane_id)
+        .expect("pane runtime")
+        .test_process_pty_bytes(b"\rPATCHED");
+    let sources = std::collections::HashSet::from([pane_id]);
+    assert!(server.render_retained_pane_surface_and_stream(&sources));
+    match read_server_message(render_rx.recv().expect("pane surface patch")) {
+        ServerMessage::PaneSurfacePatch(patch) => {
+            assert_eq!(
+                patch.base_surface_revision,
+                initial_surface.surface_revision
+            );
+            assert_eq!(patch.surface_revision, initial_surface.surface_revision + 1);
+            assert_eq!(patch.panes.len(), 1);
+            assert!(!patch.rows.is_empty());
+            assert!(patch
+                .rows
+                .iter()
+                .flat_map(|row| &row.cells)
+                .any(|cell| cell.symbol == "P"));
+        }
+        other => panic!("expected pane surface patch, got {other:?}"),
+    }
+    server
+        .app
+        .state
+        .runtime_for_pane_in_workspace(&server.app.terminal_runtimes, 0, pane_id)
+        .expect("pane runtime")
+        .test_process_pty_bytes(b"\x1b[?1003l\x1b[?1006l\x1b[?1016l");
+    assert!(server.render_retained_pane_surface_and_stream(&sources));
+    match read_server_message(render_rx.recv().expect("metadata-only pane surface patch")) {
+        ServerMessage::PaneSurfacePatch(patch) => {
+            assert_eq!(patch.panes.len(), 1);
+            assert!(!patch.panes[0].mouse_reporting);
+            assert!(!patch.panes[0].sgr_pixel_mouse);
+        }
+        other => panic!("expected metadata-only pane surface patch, got {other:?}"),
+    }
+    let retained = server.clients[&7]
+        .render_state
+        .last_pane_surface()
+        .expect("committed retained surface")
+        .clone();
+    server
+        .clients
+        .get_mut(&7)
+        .unwrap()
+        .render_state
+        .request_repaint();
+    server.render_and_stream();
+    let full = match read_server_message(render_rx.recv().expect("full comparison surface")) {
+        ServerMessage::PaneSurface(surface) => surface,
+        other => panic!("expected full comparison surface, got {other:?}"),
+    };
+    assert!(full.surface_revision > retained.surface_revision);
+    assert_eq!(retained.frame, full.frame);
+    assert_eq!(retained.panes, full.panes);
+    assert_eq!(retained.splits, full.splits);
+    shutdown_test_runtimes(&mut server);
+}
+
+fn install_shared_view_test_runtime(server: &mut HeadlessServer) -> crate::layout::PaneId {
+    let mut workspace = crate::workspace::Workspace::test_new("shared-view");
+    let pane_id = workspace.focused_pane_id().expect("focused pane");
+    workspace.insert_test_runtime(
+        pane_id,
+        crate::terminal::TerminalRuntime::test_with_screen_bytes(80, 23, b"BASE"),
+    );
+    server.app.state.workspaces = vec![workspace];
+    server.app.state.active = Some(0);
+    server.app.state.selected = 0;
+    server.app.state.mode = crate::app::Mode::Terminal;
+    pane_id
+}
+
+fn connect_test_shell(
+    server: &mut HeadlessServer,
+    client_id: u64,
+    surface_cols: u16,
+    surface_rows: u16,
+) -> (
+    std::sync::mpsc::Receiver<Vec<u8>>,
+    std::sync::mpsc::Receiver<Vec<u8>>,
+) {
+    let (writer, control, render) = test_client_writer();
+    assert!(
+        server.handle_server_event(ServerEvent::ClientShellConnected {
+            client_id,
+            surface_cols,
+            surface_rows,
+            cell_width_px: 0,
+            cell_height_px: 0,
+            pixel_mouse: false,
+            direct_graphics: false,
+            endpoint_keybindings: false,
+            mouse_capture: false,
+            writer,
+        })
+    );
+    (control, render)
+}
+
+fn connect_matching_test_shell(
+    server: &mut HeadlessServer,
+    client_id: u64,
+) -> (
+    std::sync::mpsc::Receiver<Vec<u8>>,
+    std::sync::mpsc::Receiver<Vec<u8>>,
+) {
+    connect_test_shell(server, client_id, 80, 23)
+}
+
+fn write_shared_test_pane(
+    server: &mut HeadlessServer,
+    pane_id: crate::layout::PaneId,
+    bytes: &[u8],
+) {
+    server
+        .app
+        .state
+        .runtime_for_pane_in_workspace(&server.app.terminal_runtimes, 0, pane_id)
+        .expect("pane runtime")
+        .test_process_pty_bytes(bytes);
+}
+
+fn recv_pane_surface(
+    receiver: &std::sync::mpsc::Receiver<Vec<u8>>,
+    context: &str,
+) -> crate::protocol::PaneSurfaceFrame {
+    match read_server_message(
+        receiver
+            .recv()
+            .unwrap_or_else(|error| panic!("{context}: {error}")),
+    ) {
+        ServerMessage::PaneSurface(surface) => surface,
+        other => panic!("{context}: expected pane surface, got {other:?}"),
+    }
+}
+
+fn recv_pane_surface_patch(
+    receiver: &std::sync::mpsc::Receiver<Vec<u8>>,
+    context: &str,
+) -> crate::protocol::PaneSurfacePatch {
+    match read_server_message(
+        receiver
+            .recv()
+            .unwrap_or_else(|error| panic!("{context}: {error}")),
+    ) {
+        ServerMessage::PaneSurfacePatch(patch) => patch,
+        other => panic!("{context}: expected pane surface patch, got {other:?}"),
+    }
+}
+
+#[tokio::test]
+async fn different_size_shells_receive_geometry_specific_patches_from_one_dirty_collection() {
+    let mut server = test_headless_server();
+    let pane_id = install_shared_view_test_runtime(&mut server);
+    let (large_control, large_render) = connect_test_shell(&mut server, 7, 80, 23);
+    let (small_control, small_render) = connect_test_shell(&mut server, 8, 68, 17);
+    let _ = large_control.recv().expect("large snapshot");
+    let _ = small_control.recv().expect("small snapshot");
+    server.render_and_stream();
+    let large_initial = recv_pane_surface(&large_render, "large initial surface");
+    let small_initial = recv_pane_surface(&small_render, "small initial surface");
+    assert_eq!(
+        (large_initial.frame.width, large_initial.frame.height),
+        (80, 23)
+    );
+    assert_eq!(
+        (small_initial.frame.width, small_initial.frame.height),
+        (68, 17)
+    );
+    assert_ne!(
+        large_initial.panes[0].inner_rect,
+        small_initial.panes[0].inner_rect
+    );
+
+    write_shared_test_pane(&mut server, pane_id, b"\rMIXED");
+    assert!(server.render_retained_pane_surface_and_stream(&HashSet::from([pane_id])));
+
+    let large_patch = recv_pane_surface_patch(&large_render, "large retained patch");
+    let small_patch = recv_pane_surface_patch(&small_render, "small retained patch");
+    assert_eq!(
+        large_patch.base_surface_revision,
+        large_initial.surface_revision
+    );
+    assert_eq!(
+        small_patch.base_surface_revision,
+        small_initial.surface_revision
+    );
+    assert!(large_patch.rows.iter().all(|row| {
+        row.x
+            .saturating_add(u16::try_from(row.cells.len()).unwrap_or(u16::MAX))
+            <= large_initial.frame.width
+            && row.y < large_initial.frame.height
+    }));
+    assert!(small_patch.rows.iter().all(|row| {
+        row.x
+            .saturating_add(u16::try_from(row.cells.len()).unwrap_or(u16::MAX))
+            <= small_initial.frame.width
+            && row.y < small_initial.frame.height
+    }));
+    assert_eq!(large_patch.rows, small_patch.rows);
+    assert_ne!(
+        large_patch.panes[0].inner_rect,
+        small_patch.panes[0].inner_rect
+    );
+    assert!(frame_text(
+        &server.clients[&7]
+            .render_state
+            .last_pane_surface()
+            .expect("large retained surface")
+            .frame
+    )
+    .contains("MIXED"));
+    assert!(frame_text(
+        &server.clients[&8]
+            .render_state
+            .last_pane_surface()
+            .expect("small retained surface")
+            .frame
+    )
+    .contains("MIXED"));
+
+    write_shared_test_pane(&mut server, pane_id, b"\x1b[?1049hALT");
+    assert!(!server.render_retained_pane_surface_and_stream(&HashSet::from([pane_id])));
+    server.render_and_stream();
+    let large_alt = recv_pane_surface(&large_render, "large alternate-screen surface");
+    let small_alt = recv_pane_surface(&small_render, "small alternate-screen surface");
+    assert!(large_alt.panes[0].alternate_screen_active);
+    assert!(small_alt.panes[0].alternate_screen_active);
+    assert_eq!(
+        large_alt.panes[0].inner_rect.width,
+        large_initial.panes[0].inner_rect.width + 1
+    );
+    assert_eq!(
+        small_alt.panes[0].inner_rect.width,
+        small_initial.panes[0].inner_rect.width + 1
+    );
+
+    write_shared_test_pane(&mut server, pane_id, b"\x1b[?1049l");
+    assert!(!server.render_retained_pane_surface_and_stream(&HashSet::from([pane_id])));
+    server.render_and_stream();
+    let large_main = recv_pane_surface(&large_render, "large restored main-screen surface");
+    let small_main = recv_pane_surface(&small_render, "small restored main-screen surface");
+    assert!(!large_main.panes[0].alternate_screen_active);
+    assert!(!small_main.panes[0].alternate_screen_active);
+    assert_eq!(
+        large_main.panes[0].inner_rect,
+        large_initial.panes[0].inner_rect
+    );
+    assert_eq!(
+        small_main.panes[0].inner_rect,
+        small_initial.panes[0].inner_rect
+    );
+
+    shutdown_test_runtimes(&mut server);
+}
+
+#[tokio::test]
+async fn backpressured_shell_does_not_disable_retained_patches_for_responsive_peer() {
+    let mut server = test_headless_server();
+    let pane_id = install_shared_view_test_runtime(&mut server);
+    let (responsive_control, responsive_render) = connect_matching_test_shell(&mut server, 7);
+    let (slow_control, slow_render) = connect_matching_test_shell(&mut server, 8);
+    let _ = responsive_control.recv().expect("responsive snapshot");
+    let _ = slow_control.recv().expect("slow snapshot");
+    server.render_and_stream();
+    let _ = responsive_render
+        .recv()
+        .expect("responsive initial surface");
+    let _ = slow_render.recv().expect("slow initial surface");
+
+    let sources = HashSet::from([pane_id]);
+    write_shared_test_pane(&mut server, pane_id, b"\rONE");
+    assert!(server.render_retained_pane_surface_and_stream(&sources));
+    assert!(matches!(
+        read_server_message(responsive_render.recv().expect("responsive first patch")),
+        ServerMessage::PaneSurfacePatch(_)
+    ));
+
+    write_shared_test_pane(&mut server, pane_id, b"\rTWO");
+    assert!(server.render_retained_pane_surface_and_stream(&sources));
+    assert!(matches!(
+        read_server_message(responsive_render.recv().expect("responsive second patch")),
+        ServerMessage::PaneSurfacePatch(_)
+    ));
+    assert_eq!(server.clients[&8].deferred_render(), DeferredRender::Full);
+
+    write_shared_test_pane(&mut server, pane_id, b"\rTHREE");
+    assert!(server.render_retained_pane_surface_and_stream(&sources));
+    assert!(matches!(
+        read_server_message(responsive_render.recv().expect("responsive third patch")),
+        ServerMessage::PaneSurfacePatch(_)
+    ));
+
+    assert!(matches!(
+        read_server_message(slow_render.recv().expect("slow queued first patch")),
+        ServerMessage::PaneSurfacePatch(_)
+    ));
+    assert!(server.handle_server_event(ServerEvent::ClientWriterDrained { client_id: 8 }));
+    server.render_and_stream();
+    assert!(matches!(
+        read_server_message(slow_render.recv().expect("slow full recovery surface")),
+        ServerMessage::PaneSurface(_)
+    ));
+
+    shutdown_test_runtimes(&mut server);
+}
+
+#[tokio::test]
+async fn full_render_backpressure_does_not_disable_responsive_peer_patches() {
+    let mut server = test_headless_server();
+    let pane_id = install_shared_view_test_runtime(&mut server);
+    let (responsive_control, responsive_render) = connect_matching_test_shell(&mut server, 7);
+    let (slow_control, slow_render) = connect_matching_test_shell(&mut server, 8);
+    let _ = responsive_control.recv().expect("responsive snapshot");
+    let _ = slow_control.recv().expect("slow snapshot");
+    server.render_and_stream();
+    let _ = responsive_render
+        .recv()
+        .expect("responsive initial surface");
+    // Keep the slow client's initial surface queued, then force another full
+    // replacement for both clients.
+    server.clients.get_mut(&7).unwrap().request_repaint();
+    server.clients.get_mut(&8).unwrap().request_repaint();
+    server.app.full_redraw_pending = true;
+    server.render_and_stream();
+    let _ = responsive_render
+        .recv()
+        .expect("responsive full replacement");
+    assert_eq!(server.clients[&8].deferred_render(), DeferredRender::Full);
+    assert!(!server.app.full_redraw_pending);
+
+    write_shared_test_pane(&mut server, pane_id, b"\rPATCH");
+    assert!(server.render_retained_pane_surface_and_stream(&HashSet::from([pane_id])));
+    assert!(matches!(
+        read_server_message(responsive_render.recv().expect("responsive retained patch")),
+        ServerMessage::PaneSurfacePatch(_)
+    ));
+
+    let _ = slow_render.recv().expect("slow queued initial surface");
+    assert!(server.handle_server_event(ServerEvent::ClientWriterDrained { client_id: 8 }));
+    server.render_and_stream();
+    assert!(matches!(
+        read_server_message(slow_render.recv().expect("slow full recovery surface")),
+        ServerMessage::PaneSurface(_)
+    ));
+
+    shutdown_test_runtimes(&mut server);
+}
+
+#[tokio::test]
+async fn client_shell_config_diagnostics_follow_keybinding_ownership() {
+    let mut server = test_headless_server();
+    server.server_config_diagnostic = Some("server keybinding warning\ntheme warning".into());
+    server.server_config_diagnostic_without_keybindings = Some("theme warning".into());
+
+    let (local_writer, local_control, _local_render) = test_client_writer();
+    assert!(
+        server.handle_server_event(ServerEvent::ClientShellConnected {
+            client_id: 13,
+            surface_cols: 80,
+            surface_rows: 23,
+            cell_width_px: 0,
+            cell_height_px: 0,
+            pixel_mouse: false,
+            direct_graphics: false,
+            endpoint_keybindings: false,
+            mouse_capture: false,
+            writer: local_writer,
+        })
+    );
+    let ServerMessage::ClientShellSnapshot(local_snapshot) =
+        read_server_message(local_control.recv().expect("local shell snapshot"))
+    else {
+        panic!("expected local shell snapshot");
+    };
+    assert_eq!(
+        local_snapshot.config_diagnostic.as_deref(),
+        Some("theme warning")
+    );
+
+    let (endpoint_writer, endpoint_control, _endpoint_render) = test_client_writer();
+    assert!(
+        server.handle_server_event(ServerEvent::ClientShellConnected {
+            client_id: 14,
+            surface_cols: 80,
+            surface_rows: 23,
+            cell_width_px: 0,
+            cell_height_px: 0,
+            pixel_mouse: false,
+            direct_graphics: false,
+            endpoint_keybindings: true,
+            mouse_capture: false,
+            writer: endpoint_writer,
+        })
+    );
+    let ServerMessage::ClientShellSnapshot(endpoint_snapshot) =
+        read_server_message(endpoint_control.recv().expect("endpoint shell snapshot"))
+    else {
+        panic!("expected endpoint shell snapshot");
+    };
+    assert_eq!(
+        endpoint_snapshot.config_diagnostic.as_deref(),
+        Some("server keybinding warning\ntheme warning")
+    );
+
+    shutdown_test_runtimes(&mut server);
+}
+
+#[tokio::test]
+async fn client_shell_replaces_projection_and_focuses_stable_ids() {
+    let mut server = test_headless_server();
+    let first = crate::workspace::Workspace::test_new("first");
+    let second = crate::workspace::Workspace::test_new("second");
+    server.app.state.workspaces = vec![first, second];
+    server.app.state.ensure_test_terminals();
+    server.app.state.active = Some(0);
+    server.app.state.selected = 0;
+    server.app.state.mode = crate::app::Mode::Terminal;
+    let second_id = server.app.session_snapshot().workspaces[1]
+        .workspace_id
+        .clone();
+
+    let (writer, control_rx, render_rx) = test_client_writer();
+    assert!(
+        server.handle_server_event(ServerEvent::ClientShellConnected {
+            client_id: 9,
+            surface_cols: 80,
+            surface_rows: 23,
+            cell_width_px: 0,
+            cell_height_px: 0,
+            pixel_mouse: false,
+            direct_graphics: false,
+            endpoint_keybindings: false,
+            mouse_capture: false,
+            writer,
+        })
+    );
+    let initial_revision = match read_server_message(control_rx.recv().expect("initial snapshot")) {
+        ServerMessage::ClientShellSnapshot(snapshot) => snapshot.revision,
+        other => panic!("expected initial shell snapshot, got {other:?}"),
+    };
+
+    let _ = server.app.handle_api_request(crate::api::schema::Request {
+        id: "test.client.shell.workspace.focus".into(),
+        method: crate::api::schema::Method::WorkspaceFocus(crate::api::schema::WorkspaceTarget {
+            workspace_id: second_id.clone(),
+        }),
+    });
+    assert_eq!(server.app.state.active, Some(1));
+    server.render_and_stream();
+
+    let replacement = match read_server_message(control_rx.recv().expect("replacement snapshot")) {
+        ServerMessage::ClientShellSnapshot(snapshot) => snapshot,
+        other => panic!("expected replacement shell snapshot, got {other:?}"),
+    };
+    assert!(replacement.revision > initial_revision);
+    assert_eq!(
+        replacement.focused_workspace_id.as_deref(),
+        Some(second_id.as_str())
+    );
+    match read_server_message(render_rx.recv().expect("replacement pane surface")) {
+        ServerMessage::PaneSurface(surface) => {
+            assert_eq!(surface.projection_revision, replacement.revision);
+        }
+        other => panic!("expected replacement pane surface, got {other:?}"),
+    }
+    shutdown_test_runtimes(&mut server);
+}
+
+#[tokio::test]
+async fn client_shell_input_targets_runtime_without_server_shell_classification() {
+    let mut server = test_headless_server();
+    let mut input_rx = install_focused_test_runtime(&mut server, b"\x1b[?1000h\x1b[?1006h");
+    let pane_id = server.app.session_snapshot().focused_pane_id.unwrap();
+    server.clients.insert(
+        11,
+        ClientConnection::new_with_mode(
+            ClientConnectionMode::ClientShell,
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            None,
+        ),
+    );
+
+    assert!(
+        server.handle_server_event(ServerEvent::ClientShellPaneInput {
+            client_id: 11,
+            pane_id,
+            events: vec![
+                crate::protocol::ClientPaneInputEvent::Key {
+                    code: crate::protocol::ClientKeyCode::Char('c'),
+                    modifiers: crossterm::event::KeyModifiers::CONTROL.bits(),
+                    kind: crate::protocol::ClientKeyKind::Press,
+                    repeat_count: 1,
+                    shifted_codepoint: None,
+                    generated_text: None,
+                    tracks_release: true,
+                    physical_key_id: None,
+                },
+                crate::protocol::ClientPaneInputEvent::Key {
+                    code: crate::protocol::ClientKeyCode::Char('c'),
+                    modifiers: crossterm::event::KeyModifiers::CONTROL.bits(),
+                    kind: crate::protocol::ClientKeyKind::Release,
+                    repeat_count: 1,
+                    shifted_codepoint: None,
+                    generated_text: None,
+                    tracks_release: true,
+                    physical_key_id: None,
+                },
+                crate::protocol::ClientPaneInputEvent::Key {
+                    code: crate::protocol::ClientKeyCode::Char('x'),
+                    modifiers: crossterm::event::KeyModifiers::ALT.bits(),
+                    kind: crate::protocol::ClientKeyKind::Press,
+                    repeat_count: 1,
+                    shifted_codepoint: None,
+                    generated_text: None,
+                    tracks_release: true,
+                    physical_key_id: None,
+                },
+                crate::protocol::ClientPaneInputEvent::Mouse {
+                    kind: crate::protocol::ClientMouseKind::Down(
+                        crate::protocol::ClientMouseButton::Left,
+                    ),
+                    position: crate::protocol::ClientMousePosition::Cell { column: 2, row: 1 },
+                    geometry: None,
+                    modifiers: 0,
+                    lines: 3,
+                },
+            ],
+        })
+    );
+    assert_eq!(
+        input_rx.try_recv().expect("targeted pane interrupt"),
+        Bytes::from_static(&[0x03])
+    );
+    assert_eq!(
+        input_rx.try_recv().expect("targeted pane alt key"),
+        Bytes::from_static(b"\x1bx")
+    );
+    assert_eq!(
+        input_rx.try_recv().expect("targeted pane mouse click"),
+        Bytes::from_static(b"\x1b[<0;3;2M")
+    );
+    assert_eq!(server.foreground_client_id, Some(11));
+    let pane_id = server.app.session_snapshot().focused_pane_id.unwrap();
+    assert!(server.paste_client_clipboard_image_path(
+        11,
+        crate::protocol::ClientClipboardImageTarget::Pane(pane_id.clone()),
+        "/tmp/client-image.png".into(),
+    ));
+    assert_eq!(
+        input_rx.try_recv().expect("targeted clipboard image path"),
+        Bytes::from_static(b"/tmp/client-image.png")
+    );
+    assert!(!server.paste_client_clipboard_image_path(
+        11,
+        crate::protocol::ClientClipboardImageTarget::DirectTerminal,
+        "/tmp/wrong-target.png".into(),
+    ));
+    assert!(!server.paste_client_clipboard_image_path(
+        11,
+        crate::protocol::ClientClipboardImageTarget::Popup("missing-popup".into()),
+        "/tmp/wrong-target.png".into(),
+    ));
+    assert!(input_rx.try_recv().is_err());
+
+    let (workspace_index, runtime_pane_id) = server
+        .app
+        .parse_pane_id(&pane_id)
+        .expect("runtime pane target");
+    let runtime = server
+        .app
+        .state
+        .runtime_for_pane_in_workspace(
+            &server.app.terminal_runtimes,
+            workspace_index,
+            runtime_pane_id,
+        )
+        .expect("focused runtime");
+    assert_eq!(runtime.current_size(), (24, 79));
+    assert!(input_rx.try_recv().is_err(), "legacy release emitted bytes");
+    shutdown_test_runtimes(&mut server);
+}
+
+#[tokio::test]
+async fn client_shell_hidden_pane_rejects_presses_but_accepts_releases() {
+    let mut server = test_headless_server();
+    let mut workspace = crate::workspace::Workspace::test_new("hidden-input");
+    let hidden_tab = workspace.test_add_tab(Some("hidden"));
+    let hidden_pane = workspace.tabs[hidden_tab].root_pane;
+    let (runtime, mut input_rx) =
+        crate::terminal::TerminalRuntime::test_with_channel_and_scrollback_bytes(
+            80,
+            24,
+            0,
+            b"\x1b[>3u",
+            4,
+        );
+    workspace.insert_test_runtime(hidden_pane, runtime);
+    server.app.state.workspaces = vec![workspace];
+    server.app.state.active = Some(0);
+    server.app.state.selected = 0;
+    let pane_id = server.app.public_pane_id(0, hidden_pane).unwrap();
+    server.clients.insert(
+        11,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            None,
+        ),
+    );
+    let key = |kind| crate::protocol::ClientPaneInputEvent::Key {
+        code: crate::protocol::ClientKeyCode::Char('x'),
+        modifiers: 0,
+        kind,
+        repeat_count: 1,
+        shifted_codepoint: None,
+        generated_text: None,
+        tracks_release: true,
+        physical_key_id: Some(0x2d),
+    };
+
+    assert!(
+        !server.handle_server_event(ServerEvent::ClientShellPaneInput {
+            client_id: 11,
+            pane_id: pane_id.clone(),
+            events: vec![key(crate::protocol::ClientKeyKind::Press)],
+        })
+    );
+    assert!(input_rx.try_recv().is_err());
+    assert!(
+        !server.handle_server_event(ServerEvent::ClientShellPaneInput {
+            client_id: 11,
+            pane_id,
+            events: vec![key(crate::protocol::ClientKeyKind::Release)],
+        })
+    );
+    assert!(!input_rx.recv().await.expect("encoded release").is_empty());
+    assert_eq!(server.foreground_client_id, None);
+    shutdown_test_runtimes(&mut server);
+}
+
+#[tokio::test]
+async fn client_shell_streams_and_targets_popup_terminal_content() {
+    let mut server = test_headless_server();
+    let mut pane_input = install_focused_test_runtime(&mut server, b"base-pane");
+    let (popup_runtime, mut popup_input) =
+        crate::terminal::TerminalRuntime::test_with_channel_and_scrollback_bytes(
+            40,
+            12,
+            0,
+            b"POPUP_SHELL_LIVE\x1b_Ga=T,f=32,t=d,i=9,p=4,s=1,v=1,c=1,r=1,q=2;/wAA/w==\x1b\\",
+            4,
+        );
+    let (_, popup_terminal_id) = server.app.install_test_popup_runtime(popup_runtime);
+
+    let (writer, control_rx, render_rx) = test_client_writer();
+    assert!(
+        server.handle_server_event(ServerEvent::ClientShellConnected {
+            client_id: 12,
+            surface_cols: 80,
+            surface_rows: 23,
+            cell_width_px: 10,
+            cell_height_px: 20,
+            pixel_mouse: false,
+            direct_graphics: false,
+            endpoint_keybindings: false,
+            mouse_capture: false,
+            writer,
+        })
+    );
+    assert!(matches!(
+        read_server_message(control_rx.recv().expect("shell snapshot")),
+        ServerMessage::ClientShellSnapshot(_)
+    ));
+
+    server.render_and_stream();
+    let ServerMessage::PaneSurface(surface) =
+        read_server_message(render_rx.recv().expect("popup surface"))
+    else {
+        panic!("expected pane surface");
+    };
+    let popup = surface.popup.as_deref().expect("popup terminal surface");
+    assert_eq!(popup.terminal_id, popup_terminal_id.as_str());
+    assert!(frame_text(&popup.frame).contains("POPUP_SHELL_LIVE"));
+    assert_eq!((popup.frame.width, popup.frame.height), (37, 9));
+    assert_eq!(surface.graphics.assets.len(), 1);
+    assert_eq!(surface.graphics.placements.len(), 1);
+    assert!(matches!(
+        surface.graphics.placements[0].asset.source,
+        crate::protocol::SurfaceGraphicsSource::Terminal {
+            target: crate::protocol::SurfaceGraphicsTarget::Popup { .. },
+            image_id: 9,
+        }
+    ));
+
+    assert!(
+        !server.handle_server_event(ServerEvent::ClientShellPaneInput {
+            client_id: 12,
+            pane_id: server.app.session_snapshot().focused_pane_id.unwrap(),
+            events: vec![crate::protocol::ClientPaneInputEvent::TextCommit(
+                "must-not-leak".into(),
+            )],
+        })
+    );
+    assert!(pane_input.try_recv().is_err());
+
+    assert!(server.handle_server_event(ServerEvent::ClientShellResize {
+        client_id: 12,
+        surface_cols: 60,
+        surface_rows: 15,
+        cell_width_px: 0,
+        cell_height_px: 0,
+        pixel_mouse: false,
+    }));
+    assert_eq!(
+        server
+            .app
+            .terminal_runtimes
+            .get(&popup_terminal_id)
+            .expect("popup runtime")
+            .current_size(),
+        (5, 27)
+    );
+
+    assert!(
+        !server.handle_server_event(ServerEvent::ClientShellPopupInput {
+            client_id: 12,
+            terminal_id: popup_terminal_id.to_string(),
+            events: vec![crate::protocol::ClientPaneInputEvent::TextCommit(
+                "typed".into()
+            )],
+        })
+    );
+    assert_eq!(
+        popup_input.try_recv().expect("popup input"),
+        Bytes::from_static(b"typed")
+    );
+    assert!(server.paste_client_clipboard_image_path(
+        12,
+        crate::protocol::ClientClipboardImageTarget::Popup(popup_terminal_id.to_string()),
+        "/tmp/popup-image.png".into(),
+    ));
+    assert_eq!(
+        popup_input.try_recv().expect("popup clipboard image path"),
+        Bytes::from_static(b"/tmp/popup-image.png")
+    );
+    assert!(!server.paste_client_clipboard_image_path(
+        12,
+        crate::protocol::ClientClipboardImageTarget::Popup("stale-popup".into()),
+        "/tmp/wrong-popup.png".into(),
+    ));
+    assert!(popup_input.try_recv().is_err());
+
+    assert!(
+        !server.handle_server_event(ServerEvent::ClientShellPopupInput {
+            client_id: 12,
+            terminal_id: "stale-popup".into(),
+            events: vec![crate::protocol::ClientPaneInputEvent::TextCommit(
+                "wrong".into()
+            )],
+        })
+    );
+    assert!(popup_input.try_recv().is_err());
+
+    assert!(server.app.close_popup_pane());
+    server.render_and_stream();
+    let ServerMessage::PaneSurface(surface) =
+        read_server_message(render_rx.recv().expect("popup close surface"))
+    else {
+        panic!("expected pane surface after popup close");
+    };
+    assert!(surface.popup.is_none());
+    shutdown_test_runtimes(&mut server);
+}
+
+#[tokio::test]
+async fn client_shell_release_under_popup_renders_when_it_resets_scrollback() {
+    let mut server = test_headless_server();
+    let mut workspace = crate::workspace::Workspace::test_new("popup-release-scroll");
+    let pane_id = workspace.tabs[0].root_pane;
+    let (runtime, mut input_rx) =
+        crate::terminal::TerminalRuntime::test_with_channel_and_scrollback_bytes(
+            80,
+            2,
+            10_000,
+            b"one\r\ntwo\r\nthree\r\n\x1b[>3u",
+            4,
+        );
+    runtime.scroll_up(1);
+    assert!(runtime
+        .scroll_metrics()
+        .is_some_and(|metrics| metrics.offset_from_bottom > 0));
+    workspace.insert_test_runtime(pane_id, runtime);
+    server.app.state.workspaces = vec![workspace];
+    server.app.state.active = Some(0);
+    server.app.state.selected = 0;
+    let public_pane_id = server.app.public_pane_id(0, pane_id).unwrap();
+    let popup_runtime = crate::terminal::TerminalRuntime::test_with_screen_bytes(20, 5, b"");
+    server.app.install_test_popup_runtime(popup_runtime);
+    server.clients.insert(
+        11,
+        ClientConnection::new_with_mode(
+            ClientConnectionMode::ClientShell,
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            None,
+        ),
+    );
+    server.foreground_client_id = Some(11);
+
+    let render_impact =
+        server.handle_server_event_with_render_impact(ServerEvent::ClientShellPaneInput {
+            client_id: 11,
+            pane_id: public_pane_id,
+            events: vec![crate::protocol::ClientPaneInputEvent::Key {
+                code: crate::protocol::ClientKeyCode::Char('x'),
+                modifiers: 0,
+                kind: crate::protocol::ClientKeyKind::Release,
+                repeat_count: 1,
+                shifted_codepoint: None,
+                generated_text: None,
+                tracks_release: true,
+                physical_key_id: Some(0x2d),
+            }],
+        });
+
+    assert_eq!(render_impact, RenderImpact::Full);
+    assert!(!input_rx.recv().await.expect("encoded release").is_empty());
+    shutdown_test_runtimes(&mut server);
+}
+
+#[tokio::test]
+async fn client_shell_text_input_renders_only_when_resetting_scrollback() {
+    let mut server = test_headless_server();
+    let mut workspace = crate::workspace::Workspace::test_new("scrolled-input");
+    let pane_id = workspace.tabs[0].root_pane;
+    let (runtime, mut input_rx) =
+        crate::terminal::TerminalRuntime::test_with_channel_and_scrollback_bytes(
+            80,
+            2,
+            10_000,
+            b"one\r\ntwo\r\nthree\r\n",
+            4,
+        );
+    runtime.scroll_up(1);
+    assert!(runtime
+        .scroll_metrics()
+        .is_some_and(|metrics| metrics.offset_from_bottom > 0));
+    workspace.insert_test_runtime(pane_id, runtime);
+    server.app.state.workspaces = vec![workspace];
+    server.app.state.active = Some(0);
+    server.app.state.selected = 0;
+    let public_pane_id = server.app.public_pane_id(0, pane_id).unwrap();
+    server.clients.insert(
+        11,
+        ClientConnection::new_with_mode(
+            ClientConnectionMode::ClientShell,
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            None,
+        ),
+    );
+    server.foreground_client_id = Some(11);
+
+    let render_impact =
+        server.handle_server_event_with_render_impact(ServerEvent::ClientShellPaneInput {
+            client_id: 11,
+            pane_id: public_pane_id.clone(),
+            events: vec![crate::protocol::ClientPaneInputEvent::TextCommit(
+                "x".to_owned(),
+            )],
+        });
+
+    assert_eq!(render_impact, RenderImpact::Full);
+    assert_eq!(
+        input_rx.try_recv().expect("text must reach the PTY"),
+        Bytes::from_static(b"x")
+    );
+    assert_eq!(
+        server
+            .app
+            .state
+            .runtime_for_pane_in_workspace(&server.app.terminal_runtimes, 0, pane_id)
+            .and_then(|runtime| runtime.scroll_metrics())
+            .map(|metrics| metrics.offset_from_bottom),
+        Some(0)
+    );
+
+    let render_impact =
+        server.handle_server_event_with_render_impact(ServerEvent::ClientShellPaneInput {
+            client_id: 11,
+            pane_id: public_pane_id,
+            events: vec![crate::protocol::ClientPaneInputEvent::TextCommit(
+                "y".to_owned(),
+            )],
+        });
+    assert_eq!(render_impact, RenderImpact::None);
+    assert_eq!(
+        input_rx.try_recv().expect("second text must reach the PTY"),
+        Bytes::from_static(b"y")
+    );
+    shutdown_test_runtimes(&mut server);
+}
+
+#[tokio::test]
+async fn client_shell_mouse_motion_delivers_without_render_when_foreground() {
+    let mut server = test_headless_server();
+    let mut input_rx = install_focused_test_runtime(&mut server, b"\x1b[?1003h\x1b[?1006h");
+    let pane_id = server.app.session_snapshot().focused_pane_id.unwrap();
+    server.clients.insert(
+        11,
+        ClientConnection::new_with_mode(
+            ClientConnectionMode::ClientShell,
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            None,
+        ),
+    );
+    server.foreground_client_id = Some(11);
+
+    let render_impact =
+        server.handle_server_event_with_render_impact(ServerEvent::ClientShellPaneInput {
+            client_id: 11,
+            pane_id,
+            events: vec![crate::protocol::ClientPaneInputEvent::Mouse {
+                kind: crate::protocol::ClientMouseKind::Moved,
+                position: crate::protocol::ClientMousePosition::Cell { column: 2, row: 1 },
+                geometry: None,
+                modifiers: 0,
+                lines: 0,
+            }],
+        });
+
+    assert_eq!(render_impact, RenderImpact::None);
+    assert!(
+        input_rx.try_recv().is_ok(),
+        "motion must still reach the PTY"
+    );
+    shutdown_test_runtimes(&mut server);
+}
+
+#[tokio::test]
+async fn client_shell_mouse_motion_promotes_and_requests_render() {
+    let mut server = test_headless_server();
+    let mut input_rx = install_focused_test_runtime(&mut server, b"\x1b[?1003h\x1b[?1006h");
+    let pane_id = server.app.session_snapshot().focused_pane_id.unwrap();
+    server.clients.insert(
+        11,
+        ClientConnection::new_with_mode(
+            ClientConnectionMode::ClientShell,
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            None,
+        ),
+    );
+
+    let render_impact =
+        server.handle_server_event_with_render_impact(ServerEvent::ClientShellPaneInput {
+            client_id: 11,
+            pane_id,
+            events: vec![crate::protocol::ClientPaneInputEvent::Mouse {
+                kind: crate::protocol::ClientMouseKind::Moved,
+                position: crate::protocol::ClientMousePosition::Cell { column: 2, row: 1 },
+                geometry: None,
+                modifiers: 0,
+                lines: 0,
+            }],
+        });
+
+    assert_eq!(render_impact, RenderImpact::Full);
+    assert_eq!(server.foreground_client_id, Some(11));
+    assert!(
+        input_rx.try_recv().is_ok(),
+        "motion must still reach the PTY"
+    );
+    shutdown_test_runtimes(&mut server);
+}
+
+fn install_focused_test_runtime(
+    server: &mut HeadlessServer,
+    terminal_bytes: &[u8],
+) -> tokio::sync::mpsc::Receiver<Bytes> {
+    let mut workspace = crate::workspace::Workspace::test_new("focus-reporting");
+    let pane_id = workspace.tabs[0].root_pane;
+    let (runtime, input_rx) =
+        crate::terminal::TerminalRuntime::test_with_channel_and_scrollback_bytes(
+            80,
+            24,
+            0,
+            terminal_bytes,
+            4,
+        );
+    workspace.insert_test_runtime(pane_id, runtime);
+    server.app.state.workspaces = vec![workspace];
+    server.app.state.active = Some(0);
+    server.app.state.selected = 0;
+    server.app.state.mode = crate::app::Mode::Terminal;
+    input_rx
+}
+
+fn retained_test_server(
+    initial_screen: &[u8],
+) -> (
+    HeadlessServer,
+    std::sync::mpsc::Receiver<Vec<u8>>,
+    crate::layout::PaneId,
+) {
+    let mut server = test_headless_server();
+    let mut workspace = crate::workspace::Workspace::test_new("test");
+    let pane_id = workspace.focused_pane_id().expect("focused pane");
+    workspace.insert_test_runtime(
+        pane_id,
+        crate::terminal::TerminalRuntime::test_with_screen_bytes(80, 24, initial_screen),
+    );
+    server.app.state.workspaces = vec![workspace];
+    server.app.state.active = Some(0);
+    server.app.state.selected = 0;
+    server.app.state.mode = crate::app::Mode::Terminal;
+
+    let (client_tx, _client_control_rx, client_rx) = test_client_writer();
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            Some(client_tx),
+        ),
+    );
+    server.foreground_client_id = Some(1);
+    server.sync_foreground_client_state();
+    server.resize_shared_runtime_to_effective_size();
+
+    (server, client_rx, pane_id)
+}
+
+#[test]
+fn server_keybinding_filter_keeps_whole_config_failures() {
+    assert!(!config::is_keybinding_config_diagnostic(
+        "config parse error: invalid value at `keys.new_tab = @`; using defaults"
+    ));
+    assert!(!config::is_keybinding_config_diagnostic(
+        "config read error: permission denied at keys.toml; using defaults"
+    ));
+    assert!(config::is_keybinding_config_diagnostic(
+        "unsafe direct keybinding: keys.close_pane would intercept typing"
+    ));
+}
+
+#[test]
+fn client_shell_host_theme_follows_foreground_client() {
+    let mut server = test_headless_server();
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            None,
+        ),
+    );
+    server.clients.insert(
+        2,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            2,
+            RenderEncoding::SemanticFrame,
+            None,
+        ),
+    );
+    server.foreground_client_id = Some(1);
+
+    let dark = protocol::ClientHostColor {
+        r: 20,
+        g: 30,
+        b: 40,
+    };
+    let blue = protocol::ClientHostColor {
+        r: 10,
+        g: 20,
+        b: 200,
+    };
+    assert!(
+        server.handle_server_event(ServerEvent::ClientShellHostTheme {
+            client_id: 1,
+            update: protocol::ClientHostThemeUpdate::DefaultColor {
+                kind: protocol::ClientHostDefaultColorKind::Background,
+                color: dark,
+            },
+        })
+    );
+    assert!(
+        server.handle_server_event(ServerEvent::ClientShellHostTheme {
+            client_id: 1,
+            update: protocol::ClientHostThemeUpdate::PaletteColors(vec![(4, blue)]),
+        })
+    );
+    server.handle_server_event(ServerEvent::ClientShellHostTheme {
+        client_id: 1,
+        update: protocol::ClientHostThemeUpdate::Appearance(protocol::ClientHostAppearance::Dark),
+    });
+    assert_eq!(
+        server.app.state.host_terminal_theme.background,
+        Some(dark.into())
+    );
+    assert_eq!(
+        server.app.state.host_terminal_theme.palette[4],
+        Some(blue.into())
+    );
+    assert_eq!(
+        server.app.state.host_terminal_appearance,
+        Some(crate::terminal_theme::HostAppearance::Dark)
+    );
+    assert!(server.app.state.host_terminal_appearance_explicit);
+
+    let light = protocol::ClientHostColor {
+        r: 240,
+        g: 230,
+        b: 220,
+    };
+    assert!(
+        !server.handle_server_event(ServerEvent::ClientShellHostTheme {
+            client_id: 2,
+            update: protocol::ClientHostThemeUpdate::DefaultColor {
+                kind: protocol::ClientHostDefaultColorKind::Background,
+                color: light,
+            },
+        })
+    );
+    assert_eq!(
+        server.app.state.host_terminal_theme.background,
+        Some(dark.into())
+    );
+
+    server.foreground_client_id = Some(2);
+    server.sync_foreground_client_state();
+    assert_eq!(
+        server.app.state.host_terminal_theme.background,
+        Some(light.into())
+    );
+    assert_eq!(
+        server.app.state.host_terminal_appearance,
+        Some(crate::terminal_theme::HostAppearance::Light)
+    );
+    assert!(!server.app.state.host_terminal_appearance_explicit);
+}
+
+#[test]
+fn terminal_clients_store_known_cell_geometry_independently_of_pixel_mouse() {
+    let mut server = test_headless_server();
+
+    let (writer, _control_rx, _render_rx) = test_client_writer();
+    assert!(!server.handle_server_event(ServerEvent::ClientConnected {
+        client_id: 7,
+        cols: 80,
+        rows: 24,
+        cell_width_px: 0,
+        cell_height_px: 0,
+        pixel_mouse: true,
+        writer,
+    }));
+    assert!(!server.clients[&7].pixel_mouse);
+    assert_eq!(
+        server.clients[&7].cell_size,
+        crate::kitty_graphics::HostCellSize::default()
+    );
+
+    let (writer, _control_rx, _render_rx) = test_client_writer();
+    assert!(!server.handle_server_event(ServerEvent::ClientConnected {
+        client_id: 8,
+        cols: 80,
+        rows: 24,
+        cell_width_px: 10,
+        cell_height_px: 20,
+        pixel_mouse: false,
+        writer,
+    }));
+    assert!(!server.clients[&8].pixel_mouse);
+    assert_eq!(
+        server.clients[&8].cell_size,
+        crate::kitty_graphics::HostCellSize {
+            width_px: 10,
+            height_px: 20,
+        }
+    );
+}
+
+#[test]
+fn terminal_attach_rejects_missing_terminal_and_removes_client() {
+    let mut server = test_headless_server();
+    let (writer, control_rx, _render_rx) = test_client_writer();
+
+    assert!(!server.handle_server_event(ServerEvent::ClientConnected {
+        client_id: 7,
+        cols: 80,
+        rows: 24,
+        cell_width_px: 0,
+        cell_height_px: 0,
+        pixel_mouse: false,
+        writer,
+    }));
+    assert!(matches!(
+        server.clients.get(&7).map(|client| &client.mode),
+        Some(ClientConnectionMode::TerminalPending)
+    ));
+
+    assert!(
+        !server.handle_server_event(ServerEvent::ClientAttachTerminal {
+            client_id: 7,
+            terminal_id: "term_missing".to_owned(),
+            takeover: false,
+        })
+    );
+    assert!(!server.clients.contains_key(&7));
+    let reason = read_server_shutdown_reason(control_rx.recv().expect("shutdown message"));
+    assert_eq!(
+        reason,
+        Some("terminal attach failed: terminal term_missing not found".to_owned())
+    );
+}
+
+fn with_terminal_session_test_server(
+    test: impl FnOnce(&mut HeadlessServer, crate::terminal::TerminalId, String, String),
+) {
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .expect("test runtime");
+    let _runtime_guard = rt.enter();
+    let mut server = test_headless_server();
+    let workspace = crate::workspace::Workspace::test_new("test");
+    let pane_id = workspace.tabs[0].root_pane;
+    let terminal_id = workspace.terminal_id(pane_id).expect("terminal id").clone();
+    let terminal_id_string = terminal_id.to_string();
+    let public_pane_id = format!("{}:p1", workspace.id);
+    server.app.state.workspaces = vec![workspace];
+    server.app.state.ensure_test_terminals();
+    server.app.terminal_runtimes.insert(
+        terminal_id.clone(),
+        crate::terminal::TerminalRuntime::test_with_screen_bytes(80, 24, b""),
+    );
+
+    test(&mut server, terminal_id, terminal_id_string, public_pane_id);
+
+    drop(server);
+    drop(_runtime_guard);
+    rt.shutdown_timeout(Duration::from_millis(100));
+}
+
+fn connect_pending_terminal_client(server: &mut HeadlessServer, client_id: u64) {
+    let _control_rx = connect_pending_terminal_client_with_control_rx(server, client_id);
+}
+
+fn connect_pending_terminal_client_with_control_rx(
+    server: &mut HeadlessServer,
+    client_id: u64,
+) -> std::sync::mpsc::Receiver<Vec<u8>> {
+    let (writer, control_rx, _render_rx) = test_client_writer();
+    assert!(!server.handle_server_event(ServerEvent::ClientConnected {
+        client_id,
+        cols: 100,
+        rows: 30,
+        cell_width_px: 0,
+        cell_height_px: 0,
+        pixel_mouse: false,
+        writer,
+    }));
+    assert!(matches!(
+        server.clients.get(&client_id).map(|client| &client.mode),
+        Some(ClientConnectionMode::TerminalPending)
+    ));
+    control_rx
+}
+
+#[test]
+fn explicit_agent_history_read_requires_idle_on_alternate_screen() {
+    with_terminal_session_test_server(
+        |server, terminal_id, _terminal_id_string, public_pane_id| {
+            let terminal = server
+                .app
+                .state
+                .terminals
+                .get_mut(&terminal_id)
+                .expect("terminal");
+            terminal.detected_agent = Some(crate::detect::Agent::Claude);
+            terminal.state = crate::detect::AgentState::Working;
+            server.app.terminal_runtimes.insert(
+                terminal_id,
+                crate::terminal::TerminalRuntime::test_with_screen_bytes(
+                    80,
+                    24,
+                    b"\x1b[?1049hworking",
+                ),
+            );
+            let request = api::schema::Request {
+                id: "read".into(),
+                method: api::schema::Method::AgentRead(api::schema::AgentReadParams {
+                    target: public_pane_id.clone(),
+                    source: api::schema::ReadSource::Recent,
+                    lines: Some(200),
+                    format: api::schema::ReadFormat::Text,
+                    strip_ansi: true,
+                }),
+            };
+
+            assert_eq!(
+                    server.agent_read_not_idle_error(&request),
+                    Some(api::schema::ErrorBody {
+                        code: "agent_not_idle".into(),
+                        message: format!(
+                            "cannot read 200 lines while {public_pane_id} is working: its alternate-screen history can only be captured by scrolling while idle. Wait and retry, or use --source visible"
+                        ),
+                    })
+                );
+
+            let mut default_request = request.clone();
+            let api::schema::Method::AgentRead(params) = &mut default_request.method else {
+                unreachable!();
+            };
+            params.lines = None;
+            assert_eq!(server.agent_read_not_idle_error(&default_request), None);
+
+            let mut visible_request = request;
+            let api::schema::Method::AgentRead(params) = &mut visible_request.method else {
+                unreachable!();
+            };
+            params.source = api::schema::ReadSource::Visible;
+            assert_eq!(server.agent_read_not_idle_error(&visible_request), None);
+        },
+    );
+}
+
+#[test]
+fn terminal_attach_disconnect_restores_client_shell_pane_size() {
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .expect("test runtime");
+    let _runtime_guard = rt.enter();
+    let mut server = test_headless_server();
+    let workspace = crate::workspace::Workspace::test_new("test");
+    let pane_id = workspace.tabs[0].root_pane;
+    let terminal_id = workspace.terminal_id(pane_id).expect("terminal id").clone();
+    let terminal_id_string = terminal_id.to_string();
+    server.app.state.workspaces = vec![workspace];
+    server.app.state.ensure_test_terminals();
+    server.app.state.active = Some(0);
+    server.app.state.selected = 0;
+    server.app.terminal_runtimes.insert(
+        terminal_id.clone(),
+        crate::terminal::TerminalRuntime::test_with_screen_bytes(80, 24, b""),
+    );
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (120, 40),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            None,
+        ),
+    );
+    server.foreground_client_id = Some(1);
+    server.sync_foreground_client_state();
+    server.resize_shared_runtime_to_effective_size();
+    let expected_shell_size = server
+        .app
+        .terminal_runtimes
+        .get(&terminal_id)
+        .expect("runtime")
+        .current_size();
+
+    connect_pending_terminal_client(&mut server, 2);
+    assert!(
+        server.handle_server_event(ServerEvent::ClientAttachTerminal {
+            client_id: 2,
+            terminal_id: terminal_id_string,
+            takeover: false,
+        })
+    );
+    assert_eq!(server.foreground_client_id, Some(1));
+    assert!(server
+        .app
+        .state
+        .direct_attach_resize_locks
+        .contains(&terminal_id));
+    assert_eq!(
+        server
+            .app
+            .terminal_runtimes
+            .get(&terminal_id)
+            .expect("runtime")
+            .current_size(),
+        (30, 100)
+    );
+
+    assert!(server.handle_server_event(ServerEvent::ClientDisconnected { client_id: 2 }));
+    assert!(!server
+        .app
+        .state
+        .direct_attach_resize_locks
+        .contains(&terminal_id));
+    assert_eq!(
+        server
+            .app
+            .terminal_runtimes
+            .get(&terminal_id)
+            .expect("runtime")
+            .current_size(),
+        expected_shell_size
+    );
+
+    drop(server);
+    drop(_runtime_guard);
+    rt.shutdown_timeout(Duration::from_millis(100));
+}
+
+#[test]
+fn terminal_observe_allows_multiple_clients_without_attach_ownership() {
+    with_terminal_session_test_server(|server, terminal_id, terminal_id_string, _| {
+        let initial_size = server
+            .app
+            .terminal_runtimes
+            .get(&terminal_id)
+            .expect("runtime")
+            .current_size();
+
+        for client_id in [7, 8] {
+            connect_pending_terminal_client(server, client_id);
+            assert!(
+                server.handle_server_event(ServerEvent::ClientObserveTerminal {
+                    client_id,
+                    target: terminal_id_string.clone(),
+                })
+            );
+        }
+
+        assert!(server.terminal_attach_owners.is_empty());
+        assert!(!server
+            .app
+            .state
+            .direct_attach_resize_locks
+            .contains(&terminal_id));
+        assert_eq!(
+            server
+                .app
+                .terminal_runtimes
+                .get(&terminal_id)
+                .expect("runtime")
+                .current_size(),
+            initial_size
+        );
+        assert_eq!(
+            terminal_stream_client_ids(&server.clients, &terminal_id_string).len(),
+            2
+        );
+    });
+}
+
+#[test]
+fn direct_terminal_observer_keeps_hidden_pty_source_renderable_with_client_shell() {
+    let mut server = test_headless_server();
+    let mut workspace = crate::workspace::Workspace::test_new("test");
+    let background_tab = workspace.test_add_tab(Some("background"));
+    let background_pane = workspace.tabs[background_tab].root_pane;
+    let hidden_pane = workspace.tabs[0].root_pane;
+    let terminal_id = workspace
+        .terminal_id(background_pane)
+        .expect("background terminal id")
+        .to_string();
+    server.app.state.workspaces = vec![workspace];
+    server.app.state.active = Some(0);
+    server.app.state.selected = 0;
+    server.app.state.ensure_test_terminals();
+
+    let (shell_writer, _shell_control_rx, _shell_render_rx) = test_client_writer();
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (120, 40),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            Some(shell_writer),
+        ),
+    );
+    assert!(!server.pty_sources_visible_to_any_render_target(&HashSet::from([background_pane])));
+
+    let (observer_writer, _observer_control_rx, _observer_render_rx) = test_client_writer();
+    server.clients.insert(
+        2,
+        ClientConnection::new_with_mode(
+            ClientConnectionMode::TerminalObserve { terminal_id },
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            2,
+            RenderEncoding::SemanticFrame,
+            Some(observer_writer),
+        ),
+    );
+
+    assert!(server.pty_sources_visible_to_any_render_target(&HashSet::from([background_pane])));
+    server.sync_immediate_pty_sources();
+    assert!(server.app.render_dirty.request_pty(background_pane));
+    assert!(server.has_pending_presentation_work(false, false));
+    assert!(server.app.render_dirty.request_pty(hidden_pane));
+}
+
+#[test]
+fn terminal_observe_resolves_public_pane_id() {
+    with_terminal_session_test_server(|server, terminal_id, _, public_pane_id| {
+        connect_pending_terminal_client(server, 7);
+        assert!(
+            server.handle_server_event(ServerEvent::ClientObserveTerminal {
+                client_id: 7,
+                target: public_pane_id,
+            })
+        );
+
+        assert!(matches!(
+            server.clients.get(&7).map(|client| &client.mode),
+            Some(ClientConnectionMode::TerminalObserve { terminal_id: observed })
+                if observed == &terminal_id.to_string()
+        ));
+    });
+}
+
+#[test]
+fn terminal_control_resolves_public_pane_id_and_takes_ownership() {
+    with_terminal_session_test_server(|server, terminal_id, terminal_id_string, public_pane_id| {
+        connect_pending_terminal_client(server, 7);
+        assert!(
+            server.handle_server_event(ServerEvent::ClientControlTerminal {
+                client_id: 7,
+                target: public_pane_id,
+                takeover: false,
+            })
+        );
+
+        assert!(matches!(
+            server.clients.get(&7).map(|client| &client.mode),
+            Some(ClientConnectionMode::TerminalAttach { terminal_id: attached })
+                if attached == &terminal_id_string
+        ));
+        assert_eq!(
+            server.terminal_attach_owners.get(&terminal_id_string),
+            Some(&7)
+        );
+        assert!(server
+            .app
+            .state
+            .direct_attach_resize_locks
+            .contains(&terminal_id));
+    });
+}
+
+#[test]
+fn terminal_control_rejects_attach_during_alt_screen_read() {
+    with_terminal_session_test_server(|server, terminal_id, terminal_id_string, _| {
+        let (respond_to, _response_rx) = std::sync::mpsc::channel();
+        server.pending_alt_screen_reads.push(
+            crate::server::alt_screen_read::PendingAltScreenRead::start(
+                terminal_id,
+                "read".into(),
+                respond_to,
+                "fallback".into(),
+                api::schema::PaneReadResult {
+                    pane_id: "w1:p1".into(),
+                    workspace_id: "w1".into(),
+                    tab_id: "w1:t1".into(),
+                    source: api::schema::ReadSource::Recent,
+                    format: api::schema::ReadFormat::Text,
+                    text: String::new(),
+                    revision: 0,
+                    truncated: false,
+                },
+                120,
+                false,
+                crate::terminal::ScreenSnapshot {
+                    cols: 80,
+                    rows: Vec::new(),
+                },
+                0,
+                Instant::now(),
+            ),
+        );
+        let control_rx = connect_pending_terminal_client_with_control_rx(server, 7);
+
+        assert!(
+            !server.handle_server_event(ServerEvent::ClientControlTerminal {
+                client_id: 7,
+                target: terminal_id_string.clone(),
+                takeover: false,
+            })
+        );
+        assert!(!server.clients.contains_key(&7));
+        assert!(!server
+            .terminal_attach_owners
+            .contains_key(&terminal_id_string));
+        let reason = read_server_shutdown_reason(control_rx.recv().expect("shutdown message"));
+        assert_eq!(
+                reason,
+                Some(format!(
+                    "terminal attach failed: terminal {terminal_id_string} has a read in progress; retry"
+                ))
+            );
+    });
+}
+
+#[test]
+fn terminal_control_rejects_second_controller_without_takeover() {
+    with_terminal_session_test_server(|server, _terminal_id, terminal_id_string, _| {
+        connect_pending_terminal_client(server, 7);
+        assert!(
+            server.handle_server_event(ServerEvent::ClientControlTerminal {
+                client_id: 7,
+                target: terminal_id_string.clone(),
+                takeover: false,
+            })
+        );
+
+        connect_pending_terminal_client(server, 8);
+        assert!(
+            !server.handle_server_event(ServerEvent::ClientControlTerminal {
+                client_id: 8,
+                target: terminal_id_string.clone(),
+                takeover: false,
+            })
+        );
+
+        assert!(server.clients.contains_key(&7));
+        assert!(!server.clients.contains_key(&8));
+        assert_eq!(
+            server.terminal_attach_owners.get(&terminal_id_string),
+            Some(&7)
+        );
+    });
+}
+
+#[test]
+fn terminal_control_takeover_replaces_existing_controller() {
+    with_terminal_session_test_server(|server, _terminal_id, terminal_id_string, _| {
+        connect_pending_terminal_client(server, 7);
+        assert!(
+            server.handle_server_event(ServerEvent::ClientControlTerminal {
+                client_id: 7,
+                target: terminal_id_string.clone(),
+                takeover: false,
+            })
+        );
+
+        connect_pending_terminal_client(server, 8);
+        assert!(
+            server.handle_server_event(ServerEvent::ClientControlTerminal {
+                client_id: 8,
+                target: terminal_id_string.clone(),
+                takeover: true,
+            })
+        );
+
+        assert!(!server.clients.contains_key(&7));
+        assert!(server.clients.contains_key(&8));
+        assert_eq!(
+            server.terminal_attach_owners.get(&terminal_id_string),
+            Some(&8)
+        );
+    });
+}
+
+#[test]
+fn terminal_observe_can_coexist_with_terminal_control() {
+    with_terminal_session_test_server(|server, _terminal_id, terminal_id_string, _| {
+        connect_pending_terminal_client(server, 7);
+        assert!(
+            server.handle_server_event(ServerEvent::ClientControlTerminal {
+                client_id: 7,
+                target: terminal_id_string.clone(),
+                takeover: false,
+            })
+        );
+
+        connect_pending_terminal_client(server, 8);
+        assert!(
+            server.handle_server_event(ServerEvent::ClientObserveTerminal {
+                client_id: 8,
+                target: terminal_id_string.clone(),
+            })
+        );
+
+        assert_eq!(
+            server.terminal_attach_owners.get(&terminal_id_string),
+            Some(&7)
+        );
+        assert!(matches!(
+            server.clients.get(&8).map(|client| &client.mode),
+            Some(ClientConnectionMode::TerminalObserve { terminal_id })
+                if terminal_id == &terminal_id_string
+        ));
+        assert_eq!(
+            terminal_stream_client_ids(&server.clients, &terminal_id_string).len(),
+            2
+        );
+    });
+}
+
+#[test]
+fn terminal_control_detach_sends_shutdown_before_removal() {
+    with_terminal_session_test_server(|server, _terminal_id, terminal_id_string, _| {
+        let control_rx = connect_pending_terminal_client_with_control_rx(server, 7);
+        assert!(
+            server.handle_server_event(ServerEvent::ClientControlTerminal {
+                client_id: 7,
+                target: terminal_id_string.clone(),
+                takeover: false,
+            })
+        );
+
+        assert!(server.handle_server_event(ServerEvent::ClientDetach { client_id: 7 }));
+
+        assert!(!server.clients.contains_key(&7));
+        assert!(!server
+            .terminal_attach_owners
+            .contains_key(&terminal_id_string));
+        let reason = read_server_shutdown_reason(control_rx.recv().expect("shutdown message"));
+        assert_eq!(reason, Some("detached".to_owned()));
+    });
+}
+
+#[test]
+fn terminal_observe_rejects_later_attach_upgrade() {
+    with_terminal_session_test_server(|server, terminal_id, terminal_id_string, _| {
+        connect_pending_terminal_client(server, 7);
+        assert!(
+            server.handle_server_event(ServerEvent::ClientObserveTerminal {
+                client_id: 7,
+                target: terminal_id_string.clone(),
+            })
+        );
+        assert!(
+            !server.handle_server_event(ServerEvent::ClientAttachTerminal {
+                client_id: 7,
+                terminal_id: terminal_id_string,
+                takeover: true,
+            })
+        );
+
+        assert!(!server.clients.contains_key(&7));
+        assert!(server.terminal_attach_owners.is_empty());
+        assert!(!server
+            .app
+            .state
+            .direct_attach_resize_locks
+            .contains(&terminal_id));
+    });
+}
+
+#[test]
+fn terminal_attach_rejects_later_observe_and_clears_ownership() {
+    with_terminal_session_test_server(|server, terminal_id, terminal_id_string, _| {
+        connect_pending_terminal_client(server, 7);
+        assert!(
+            server.handle_server_event(ServerEvent::ClientAttachTerminal {
+                client_id: 7,
+                terminal_id: terminal_id_string.clone(),
+                takeover: false,
+            })
+        );
+        assert_eq!(
+            server.terminal_attach_owners.get(&terminal_id_string),
+            Some(&7)
+        );
+        assert!(server
+            .app
+            .state
+            .direct_attach_resize_locks
+            .contains(&terminal_id));
+
+        assert!(
+            !server.handle_server_event(ServerEvent::ClientObserveTerminal {
+                client_id: 7,
+                target: terminal_id_string.clone(),
+            })
+        );
+
+        assert!(!server.clients.contains_key(&7));
+        assert!(server.terminal_attach_owners.is_empty());
+        assert!(!server
+            .app
+            .state
+            .direct_attach_resize_locks
+            .contains(&terminal_id));
+    });
+}
+
+#[test]
+fn unchanged_git_refresh_does_not_request_headless_render() {
+    let mut server = test_headless_server();
+    server.app.git_refresh_in_flight = true;
+    let mut workspace = crate::workspace::Workspace::test_new("one");
+    let workspace_id = workspace.id.clone();
+    let cwd = workspace.identity_cwd.clone();
+    workspace.cached_auto_label = "cached".into();
+    workspace.cached_git_status_key = cwd.clone();
+    workspace.cached_git_branch = None;
+    server.app.state.workspaces.push(workspace);
+
+    let changed = server.handle_internal_event_with_forwarding(AppEvent::GitStatusRefreshed {
+        results: vec![crate::workspace::WorkspaceGitStatus {
+            workspace_id,
+            resolved_identity_cwd: cwd.clone(),
+            status_cache_key: cwd,
+            demand: crate::workspace::GitStatusRefreshDemand::ALL,
+            auto_label: "cached".into(),
+            branch: None,
+            ahead_behind: None,
+            space: None,
+        }],
+        cache_updates: Vec::new(),
+    });
+
+    assert!(!changed);
+    assert!(!server.app.git_refresh_in_flight);
+}
+
+#[test]
+fn changed_git_refresh_requests_headless_render() {
+    let mut server = test_headless_server();
+    let workspace = crate::workspace::Workspace::test_new("one");
+    let workspace_id = workspace.id.clone();
+    let cwd = workspace.identity_cwd.clone();
+    server.app.state.workspaces.push(workspace);
+
+    let changed = server.handle_internal_event_with_forwarding(AppEvent::GitStatusRefreshed {
+        results: vec![crate::workspace::WorkspaceGitStatus {
+            workspace_id,
+            resolved_identity_cwd: cwd.clone(),
+            status_cache_key: cwd,
+            demand: crate::workspace::GitStatusRefreshDemand::ALL,
+            auto_label: "one".into(),
+            branch: Some("changed".into()),
+            ahead_behind: None,
+            space: None,
+        }],
+        cache_updates: Vec::new(),
+    });
+
+    assert!(changed);
+}
+
+#[test]
+fn terminal_attach_client_exits_when_attached_pane_dies() {
+    let mut server = test_headless_server();
+    let workspace = crate::workspace::Workspace::test_new("attached");
+    let pane_id = workspace.tabs[0].root_pane;
+    server.app.state.workspaces = vec![workspace];
+    server.app.state.ensure_test_terminals();
+    let terminal_id = server.app.state.workspaces[0]
+        .pane_state(pane_id)
+        .expect("pane")
+        .attached_terminal_id
+        .to_string();
+    let (writer, control_rx, _render_rx) = test_client_writer();
+
+    assert!(!server.handle_server_event(ServerEvent::ClientConnected {
+        client_id: 7,
+        cols: 80,
+        rows: 24,
+        cell_width_px: 0,
+        cell_height_px: 0,
+        pixel_mouse: false,
+        writer,
+    }));
+    assert!(
+        server.handle_server_event(ServerEvent::ClientAttachTerminal {
+            client_id: 7,
+            terminal_id: terminal_id.clone(),
+            takeover: false,
+        })
+    );
+    assert_eq!(server.terminal_attach_owners.get(&terminal_id), Some(&7));
+
+    assert!(server.handle_internal_event_with_forwarding(AppEvent::PaneDied { pane_id }));
+
+    assert!(!server.clients.contains_key(&7));
+    assert!(!server.terminal_attach_owners.contains_key(&terminal_id));
+    let reason = read_server_shutdown_reason(control_rx.recv().expect("shutdown message"));
+    assert_eq!(reason, Some(format!("terminal {terminal_id} exited")));
+}
+
+#[test]
+fn terminal_attach_scroll_moves_attached_runtime_viewport() {
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .expect("test runtime");
+    let _runtime_guard = rt.enter();
+    let mut bytes = Vec::new();
+    for line in 0..80 {
+        bytes.extend_from_slice(format!("line {line:02}\r\n").as_bytes());
+    }
+    let runtime = crate::terminal::TerminalRuntime::test_with_scrollback_bytes(20, 5, 4096, &bytes);
+
+    apply_terminal_attach_scroll(
+        &runtime,
+        AttachScrollSource::Wheel,
+        AttachScrollDirection::Up,
+        3,
+        None,
+        None,
+        0,
+    )
+    .expect("scroll up");
+    let metrics = runtime.scroll_metrics().expect("scroll metrics");
+    assert_eq!(metrics.offset_from_bottom, 3);
+
+    apply_terminal_attach_scroll(
+        &runtime,
+        AttachScrollSource::Wheel,
+        AttachScrollDirection::Down,
+        2,
+        None,
+        None,
+        0,
+    )
+    .expect("scroll down");
+    let metrics = runtime.scroll_metrics().expect("scroll metrics");
+    assert_eq!(metrics.offset_from_bottom, 1);
+    drop(runtime);
+    drop(_runtime_guard);
+    rt.shutdown_timeout(Duration::from_millis(100));
+}
+
+#[test]
+fn client_pane_pixel_mouse_uses_runtime_pixel_encoding() {
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .expect("test runtime");
+    let _runtime_guard = rt.enter();
+    let (runtime, mut input_rx) =
+        crate::terminal::TerminalRuntime::test_with_channel_and_scrollback_bytes(
+            20,
+            5,
+            0,
+            b"\x1b[?1003h\x1b[?1006h\x1b[?1016h",
+            4,
+        );
+    runtime.resize(5, 20, 10, 20);
+
+    apply_client_pane_input_events(
+        &runtime,
+        &[crate::protocol::ClientPaneInputEvent::Mouse {
+            kind: crate::protocol::ClientMouseKind::Moved,
+            position: crate::protocol::ClientMousePosition::Pixels {
+                x: 21,
+                y: 22,
+                column: 2,
+                row: 1,
+            },
+            geometry: None,
+            modifiers: 0,
+            lines: 3,
+        }],
+    )
+    .expect("pixel mouse input");
+    assert_eq!(
+        input_rx.try_recv().expect("encoded pixel mouse"),
+        Bytes::from_static(b"\x1b[<35;21;22M")
+    );
+    drop(runtime);
+    drop(_runtime_guard);
+    rt.shutdown_timeout(Duration::from_millis(100));
+}
+
+#[test]
+fn client_pane_pixel_mouse_falls_back_to_canonical_cell_position() {
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .expect("test runtime");
+    let _runtime_guard = rt.enter();
+    let (runtime, mut input_rx) =
+        crate::terminal::TerminalRuntime::test_with_channel_and_scrollback_bytes(
+            20,
+            5,
+            0,
+            b"\x1b[?1003h\x1b[?1006h",
+            4,
+        );
+    runtime.resize(5, 20, 10, 20);
+
+    apply_client_pane_input_events(
+        &runtime,
+        &[crate::protocol::ClientPaneInputEvent::Mouse {
+            kind: crate::protocol::ClientMouseKind::Moved,
+            position: crate::protocol::ClientMousePosition::Pixels {
+                x: 21,
+                y: 22,
+                column: 2,
+                row: 1,
+            },
+            geometry: None,
+            modifiers: 0,
+            lines: 3,
+        }],
+    )
+    .expect("cell mouse fallback");
+    assert_eq!(
+        input_rx.try_recv().expect("encoded cell mouse"),
+        Bytes::from_static(b"\x1b[<35;3;2M")
+    );
+    drop(runtime);
+    drop(_runtime_guard);
+    rt.shutdown_timeout(Duration::from_millis(100));
+}
+
+#[test]
+fn client_pane_wheel_input_accumulates_scrollback_offset() {
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .expect("test runtime");
+    let _runtime_guard = rt.enter();
+    let mut bytes = Vec::new();
+    for line in 0..80 {
+        bytes.extend_from_slice(format!("line {line:02}\r\n").as_bytes());
+    }
+    let (runtime, mut input_rx) =
+        crate::terminal::TerminalRuntime::test_with_channel_and_scrollback_bytes(
+            20, 5, 4096, &bytes, 4,
+        );
+    let scroll = |kind| crate::protocol::ClientPaneInputEvent::Mouse {
+        kind,
+        position: crate::protocol::ClientMousePosition::Cell { column: 2, row: 1 },
+        geometry: None,
+        modifiers: 0,
+        lines: 3,
+    };
+
+    apply_client_pane_input_events(
+        &runtime,
+        &[scroll(crate::protocol::ClientMouseKind::ScrollUp)],
+    )
+    .expect("first scroll up");
+    apply_client_pane_input_events(
+        &runtime,
+        &[scroll(crate::protocol::ClientMouseKind::ScrollUp)],
+    )
+    .expect("second scroll up");
+    assert_eq!(
+        runtime
+            .scroll_metrics()
+            .expect("scroll metrics")
+            .offset_from_bottom,
+        6
+    );
+
+    apply_client_pane_input_events(
+        &runtime,
+        &[scroll(crate::protocol::ClientMouseKind::ScrollDown)],
+    )
+    .expect("scroll down");
+    assert_eq!(
+        runtime
+            .scroll_metrics()
+            .expect("scroll metrics")
+            .offset_from_bottom,
+        3
+    );
+
+    runtime.test_process_pty_bytes(b"\x1b[?1003h\x1b[?1006h");
+    apply_client_pane_input_events(
+        &runtime,
+        &[crate::protocol::ClientPaneInputEvent::Mouse {
+            kind: crate::protocol::ClientMouseKind::Moved,
+            position: crate::protocol::ClientMousePosition::Cell { column: 2, row: 1 },
+            geometry: None,
+            modifiers: 0,
+            lines: 3,
+        }],
+    )
+    .expect("reported mouse motion");
+    assert_eq!(
+        runtime
+            .scroll_metrics()
+            .expect("scroll metrics")
+            .offset_from_bottom,
+        3
+    );
+    assert_eq!(
+        input_rx.try_recv().expect("reported mouse motion"),
+        Bytes::from_static(b"\x1b[<35;3;2M")
+    );
+
+    apply_client_pane_input_events(
+        &runtime,
+        &[crate::protocol::ClientPaneInputEvent::Mouse {
+            kind: crate::protocol::ClientMouseKind::Down(crate::protocol::ClientMouseButton::Left),
+            position: crate::protocol::ClientMousePosition::Cell { column: 2, row: 1 },
+            geometry: None,
+            modifiers: 0,
+            lines: 3,
+        }],
+    )
+    .expect("mouse button");
+    assert_eq!(
+        runtime
+            .scroll_metrics()
+            .expect("scroll metrics")
+            .offset_from_bottom,
+        0
+    );
+    assert_eq!(
+        input_rx.try_recv().expect("reported mouse button"),
+        Bytes::from_static(b"\x1b[<0;3;2M")
+    );
+    drop(runtime);
+    drop(_runtime_guard);
+    rt.shutdown_timeout(Duration::from_millis(100));
+}
+
+#[test]
+fn terminal_attach_input_resets_scrolled_viewport() {
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .expect("test runtime");
+    let _runtime_guard = rt.enter();
+    let mut bytes = Vec::new();
+    for line in 0..80 {
+        bytes.extend_from_slice(format!("line {line:02}\r\n").as_bytes());
+    }
+    let (runtime, mut input_rx) =
+        crate::terminal::TerminalRuntime::test_with_channel_and_scrollback_bytes(
+            20, 5, 4096, &bytes, 4,
+        );
+
+    runtime.scroll_up(4);
+    assert_eq!(
+        runtime
+            .scroll_metrics()
+            .expect("scroll metrics")
+            .offset_from_bottom,
+        4
+    );
+
+    apply_terminal_attach_input(&runtime, b"x".to_vec()).expect("attach input");
+    assert_eq!(
+        runtime
+            .scroll_metrics()
+            .expect("scroll metrics")
+            .offset_from_bottom,
+        0
+    );
+    assert_eq!(
+        input_rx.try_recv().expect("forwarded input"),
+        Bytes::from("x")
+    );
+
+    drop(runtime);
+    drop(_runtime_guard);
+    rt.shutdown_timeout(Duration::from_millis(100));
+}
+
+fn with_terminal_attach_runtime(
+    initial_bytes: &[u8],
+    initial_scroll: usize,
+    test: impl FnOnce(&crate::terminal::TerminalRuntime, &mut mpsc::Receiver<Bytes>),
+) {
+    let rt = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .expect("test runtime");
+    let _runtime_guard = rt.enter();
+    let mut bytes = initial_bytes.to_vec();
+    for line in 0..80 {
+        bytes.extend_from_slice(format!("line {line:02}\r\n").as_bytes());
+    }
+    let (runtime, mut input_rx) =
+        crate::terminal::TerminalRuntime::test_with_channel_and_scrollback_bytes(
+            20, 5, 4096, &bytes, 4,
+        );
+    if initial_scroll > 0 {
+        runtime.scroll_up(initial_scroll);
+    }
+
+    test(&runtime, &mut input_rx);
+
+    drop(runtime);
+    drop(_runtime_guard);
+    rt.shutdown_timeout(Duration::from_millis(100));
+}
+
+fn apply_terminal_attach_page_up(runtime: &crate::terminal::TerminalRuntime) {
+    apply_terminal_attach_scroll(
+        runtime,
+        AttachScrollSource::PageKey {
+            input: b"\x1b[5~".to_vec(),
+        },
+        AttachScrollDirection::Up,
+        4,
+        None,
+        None,
+        0,
+    )
+    .expect("page key");
+}
+
+fn client_page_key(
+    code: crate::protocol::ClientKeyCode,
+    modifiers: crossterm::event::KeyModifiers,
+    kind: crate::protocol::ClientKeyKind,
+) -> crate::protocol::ClientPaneInputEvent {
+    crate::protocol::ClientPaneInputEvent::Key {
+        code,
+        modifiers: modifiers.bits(),
+        kind,
+        repeat_count: 1,
+        shifted_codepoint: None,
+        generated_text: None,
+        tracks_release: true,
+        physical_key_id: None,
+    }
+}
+
+#[test]
+fn client_plain_page_keys_scroll_shell_transcript_by_pane_height() {
+    with_terminal_attach_runtime(b"", 0, |runtime, input_rx| {
+        apply_client_pane_input_events(
+            runtime,
+            &[client_page_key(
+                crate::protocol::ClientKeyCode::PageUp,
+                crossterm::event::KeyModifiers::empty(),
+                crate::protocol::ClientKeyKind::Press,
+            )],
+        )
+        .expect("pane PageUp");
+        assert_eq!(
+            runtime
+                .scroll_metrics()
+                .expect("scroll metrics")
+                .offset_from_bottom,
+            5
+        );
+
+        apply_client_pane_input_events(
+            runtime,
+            &[client_page_key(
+                crate::protocol::ClientKeyCode::PageUp,
+                crossterm::event::KeyModifiers::empty(),
+                crate::protocol::ClientKeyKind::Release,
+            )],
+        )
+        .expect("pane PageUp release");
+        assert_eq!(
+            runtime
+                .scroll_metrics()
+                .expect("scroll metrics")
+                .offset_from_bottom,
+            5
+        );
+
+        apply_client_pane_input_events(
+            runtime,
+            &[client_page_key(
+                crate::protocol::ClientKeyCode::PageDown,
+                crossterm::event::KeyModifiers::empty(),
+                crate::protocol::ClientKeyKind::Press,
+            )],
+        )
+        .expect("pane PageDown");
+        assert_eq!(
+            runtime
+                .scroll_metrics()
+                .expect("scroll metrics")
+                .offset_from_bottom,
+            0
+        );
+        assert!(input_rx.try_recv().is_err(), "page keys reached the shell");
+    });
+}
+
+#[test]
+fn client_page_keys_forward_when_modified_or_owned_by_application() {
+    with_terminal_attach_runtime(b"", 0, |runtime, input_rx| {
+        apply_client_pane_input_events(
+            runtime,
+            &[client_page_key(
+                crate::protocol::ClientKeyCode::PageUp,
+                crossterm::event::KeyModifiers::CONTROL,
+                crate::protocol::ClientKeyKind::Press,
+            )],
+        )
+        .expect("modified pane PageUp");
+        assert!(
+            input_rx.try_recv().is_ok(),
+            "modified PageUp was not forwarded"
+        );
+        assert_eq!(
+            runtime
+                .scroll_metrics()
+                .expect("scroll metrics")
+                .offset_from_bottom,
+            0
+        );
+    });
+
+    with_terminal_attach_runtime(b"\x1b[?1h", 0, |runtime, input_rx| {
+        apply_client_pane_input_events(
+            runtime,
+            &[client_page_key(
+                crate::protocol::ClientKeyCode::PageUp,
+                crossterm::event::KeyModifiers::empty(),
+                crate::protocol::ClientKeyKind::Press,
+            )],
+        )
+        .expect("application PageUp");
+        assert_eq!(
+            input_rx.try_recv().expect("forwarded application PageUp"),
+            Bytes::from_static(b"\x1b[5~")
+        );
+        assert_eq!(
+            runtime
+                .scroll_metrics()
+                .expect("scroll metrics")
+                .offset_from_bottom,
+            0
+        );
+    });
+}
+
+#[test]
+fn client_popup_plain_page_key_remains_popup_input() {
+    with_terminal_attach_runtime(b"", 0, |runtime, input_rx| {
+        apply_client_popup_input_events(
+            runtime,
+            &[client_page_key(
+                crate::protocol::ClientKeyCode::PageUp,
+                crossterm::event::KeyModifiers::empty(),
+                crate::protocol::ClientKeyKind::Press,
+            )],
+        )
+        .expect("popup PageUp");
+        assert_eq!(
+            input_rx.try_recv().expect("forwarded popup PageUp"),
+            Bytes::from_static(b"\x1b[5~")
+        );
+        assert_eq!(
+            runtime
+                .scroll_metrics()
+                .expect("scroll metrics")
+                .offset_from_bottom,
+            0
+        );
+    });
+}
+
+#[test]
+fn terminal_attach_paste_uses_plain_text_when_runtime_did_not_enable_brackets() {
+    with_terminal_attach_runtime(b"", 0, |runtime, input_rx| {
+        apply_terminal_attach_input(runtime, b"\x1b[200~line one\nline two\x1b[201~".to_vec())
+            .expect("attach paste");
+
+        assert_eq!(
+            input_rx.try_recv().expect("forwarded paste"),
+            Bytes::from_static(b"line one\nline two")
+        );
+    });
+}
+
+#[test]
+fn terminal_attach_paste_preserves_brackets_when_runtime_enabled_them() {
+    with_terminal_attach_runtime(b"\x1b[?2004h", 0, |runtime, input_rx| {
+        apply_terminal_attach_input(runtime, b"\x1b[200~line one\nline two\x1b[201~".to_vec())
+            .expect("attach paste");
+
+        assert_eq!(
+            input_rx.try_recv().expect("forwarded paste"),
+            Bytes::from_static(b"\x1b[200~line one\nline two\x1b[201~")
+        );
+    });
+}
+
+#[test]
+fn terminal_attach_page_key_host_scrolls_plain_terminal() {
+    with_terminal_attach_runtime(b"", 0, |runtime, input_rx| {
+        apply_terminal_attach_page_up(runtime);
+
+        assert_eq!(
+            runtime
+                .scroll_metrics()
+                .expect("scroll metrics")
+                .offset_from_bottom,
+            4
+        );
+        assert!(input_rx.try_recv().is_err());
+    });
+}
+
+#[test]
+fn terminal_attach_page_key_forwards_when_mouse_reporting() {
+    with_terminal_attach_runtime(b"\x1b[?1000h", 3, |runtime, input_rx| {
+        apply_terminal_attach_page_up(runtime);
+
+        assert_eq!(
+            runtime
+                .scroll_metrics()
+                .expect("scroll metrics")
+                .offset_from_bottom,
+            0
+        );
+        assert_eq!(
+            input_rx.try_recv().expect("forwarded page key"),
+            Bytes::from_static(b"\x1b[5~")
+        );
+    });
+}
+
+#[test]
+fn terminal_attach_page_key_forwards_when_application_cursor() {
+    with_terminal_attach_runtime(b"\x1b[?1h", 3, |runtime, input_rx| {
+        apply_terminal_attach_page_up(runtime);
+
+        assert_eq!(
+            runtime
+                .scroll_metrics()
+                .expect("scroll metrics")
+                .offset_from_bottom,
+            0
+        );
+        assert_eq!(
+            input_rx.try_recv().expect("forwarded page key"),
+            Bytes::from_static(b"\x1b[5~")
+        );
+    });
+}
+
+#[test]
+fn terminal_attach_page_key_host_scrolls_shell_like_decckm_with_bracketed_paste() {
+    with_terminal_attach_runtime(b"\x1b[?1h\x1b[?2004h", 0, |runtime, input_rx| {
+        apply_terminal_attach_page_up(runtime);
+
+        assert_eq!(
+            runtime
+                .scroll_metrics()
+                .expect("scroll metrics")
+                .offset_from_bottom,
+            4
+        );
+        assert!(input_rx.try_recv().is_err());
+    });
+}
+
+#[test]
+fn terminal_attach_page_key_forwards_in_alternate_screen_without_mouse_reporting() {
+    with_terminal_attach_runtime(b"\x1b[?1049h", 3, |runtime, input_rx| {
+        apply_terminal_attach_page_up(runtime);
+
+        assert_eq!(
+            runtime
+                .scroll_metrics()
+                .expect("scroll metrics")
+                .offset_from_bottom,
+            0
+        );
+        assert_eq!(
+            input_rx.try_recv().expect("forwarded page key"),
+            Bytes::from_static(b"\x1b[5~")
+        );
+    });
+}
+
+#[test]
+fn headless_scheduled_tasks_expire_agent_metadata() {
+    let mut server = test_headless_server();
+    let workspace = crate::workspace::Workspace::test_new("metadata");
+    let pane_id = workspace.tabs[0].root_pane;
+    server.app.state.workspaces = vec![workspace];
+    server.app.state.ensure_test_terminals();
+
+    assert!(
+        server.handle_internal_event_with_forwarding(AppEvent::HookStateReported {
+            pane_id,
+            source: "custom:pi".into(),
+            agent_label: "pi".into(),
+            state: crate::detect::AgentState::Working,
+            message: None,
+            seq: None,
+            session_ref: None,
+        })
+    );
+    assert!(
+        server.handle_internal_event_with_forwarding(AppEvent::HookMetadataReported {
+            pane_id,
+            source: "user:pi-display".into(),
+            agent_label: Some("pi".into()),
+            applies_to_source: Some("custom:pi".into()),
+            title: Some("short lived".into()),
+            display_agent: None,
+            state_labels: HashMap::new(),
+            clear_title: false,
+            clear_display_agent: false,
+            clear_state_labels: false,
+            seq: None,
+            // Expiry is advanced with the captured deadline below; keep the
+            // pre-expiry assertion independent of wall-clock scheduling.
+            ttl: Some(Duration::from_secs(60)),
+        })
+    );
+
+    let deadline = server
+        .app
+        .agent_metadata_deadline
+        .expect("metadata deadline");
+    let terminal_id = server.app.state.workspaces[0]
+        .pane_state(pane_id)
+        .expect("pane")
+        .attached_terminal_id
+        .clone();
+    assert_eq!(
+        server
+            .app
+            .state
+            .terminals
+            .get(&terminal_id)
+            .expect("terminal")
+            .effective_title()
+            .as_deref(),
+        Some("short lived")
+    );
+
+    assert!(server.handle_scheduled_tasks_headless(deadline + Duration::from_millis(1), false));
+
+    assert_eq!(server.app.agent_metadata_deadline, None);
+    assert_eq!(
+        server
+            .app
+            .state
+            .terminals
+            .get(&terminal_id)
+            .expect("terminal")
+            .effective_title(),
+        None
+    );
+    assert!(server
+        .app
+        .event_hub
+        .events_after(0)
+        .iter()
+        .any(|(_, event)| {
+            event.event == crate::api::schema::EventKind::PaneAgentStatusChanged
+                && matches!(
+                    &event.data,
+                    crate::api::schema::EventData::PaneAgentStatusChanged {
+                        title,
+                        ..
+                    } if title.is_none()
+                )
+        }));
+}
+
+#[test]
+fn headless_scheduled_tasks_clears_disabled_agent_manifest_update_deadline() {
+    let mut server = test_headless_server();
+    let now = Instant::now();
+    server.app.next_agent_manifest_update_check = Some(now - Duration::from_millis(1));
+
+    assert!(!server.handle_scheduled_tasks_headless(now, false));
+    assert_eq!(server.app.next_agent_manifest_update_check, None);
+}
+
+#[cfg(unix)]
+#[tokio::test]
+async fn headless_scheduled_tasks_start_pending_agent_resume_without_foreground_client() {
+    let mut server = test_headless_server();
+    let workspace = crate::workspace::Workspace::test_new("restored");
+    let pane_id = workspace.tabs[0].root_pane;
+    let terminal_id = workspace.terminal_id(pane_id).cloned().unwrap();
+    server.app.state.workspaces = vec![workspace];
+    server.app.state.active = Some(0);
+    server.app.state.ensure_test_terminals();
+    server
+        .app
+        .state
+        .terminals
+        .get_mut(&terminal_id)
+        .expect("test terminal should exist")
+        .pending_agent_resume_plan = Some(crate::agent_resume::AgentResumePlan {
+        agent: "codex".into(),
+        argv: vec!["/bin/sh".into(), "-c".into(), "sleep 5".into()],
+        dedupe_key: "herdr:codex\0codex\0Id\0codex-session".into(),
+    });
+
+    server.render_and_stream();
+    assert_ne!(server.app.state.view.terminal_area, Rect::default());
+
+    let now = Instant::now();
+    assert!(!server.handle_scheduled_tasks_headless(now, false));
+    assert!(server.app.terminal_runtimes.get(&terminal_id).is_none());
+    let deadline = server
+        .app
+        .pending_agent_resume_deadline
+        .expect("clientless resume should wait briefly for a host theme");
+
+    assert!(server.handle_scheduled_tasks_headless(deadline, false));
+    assert!(server.app.terminal_runtimes.get(&terminal_id).is_some());
+    assert!(server
+        .app
+        .state
+        .terminals
+        .get(&terminal_id)
+        .expect("test terminal should still exist")
+        .pending_agent_resume_plan
+        .is_none());
+    shutdown_test_runtimes(&mut server);
+}
+
+#[test]
+fn terminal_attach_resize_uses_known_cell_geometry_without_pixel_mouse() {
+    with_terminal_session_test_server(|server, _other_terminal_id, terminal_id, _pane_id| {
+        let mut client = ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            None,
+        );
+        client.mode = ClientConnectionMode::TerminalAttach {
+            terminal_id: terminal_id.clone(),
+        };
+        server.clients.insert(1, client);
+
+        assert!(server.handle_server_event(ServerEvent::ClientResize {
+            client_id: 1,
+            cols: 100,
+            rows: 30,
+            cell_width_px: 8,
+            cell_height_px: 16,
+            pixel_mouse: false,
+        }));
+        assert_eq!(
+            server
+                .runtime_for_terminal_id_string(&terminal_id)
+                .unwrap()
+                .pixel_size(),
+            Some((800, 480))
+        );
+        assert_eq!(
+            server.clients[&1].cell_size,
+            crate::kitty_graphics::HostCellSize {
+                width_px: 8,
+                height_px: 16,
+            }
+        );
+        assert!(!server.clients[&1].pixel_mouse);
+
+        assert!(server.handle_server_event(ServerEvent::ClientResize {
+            client_id: 1,
+            cols: 100,
+            rows: 30,
+            cell_width_px: 0,
+            cell_height_px: 0,
+            pixel_mouse: false,
+        }));
+        assert_eq!(
+            server
+                .runtime_for_terminal_id_string(&terminal_id)
+                .unwrap()
+                .pixel_size(),
+            None
+        );
+        assert_eq!(
+            server.clients[&1].cell_size,
+            crate::kitty_graphics::HostCellSize::default()
+        );
+        assert!(!server.clients[&1].pixel_mouse);
+    });
+}
+
+#[test]
+fn pending_terminal_resize_does_not_take_shell_foreground_or_geometry() {
+    let mut server = test_headless_server();
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (100, 30),
+            crate::kitty_graphics::HostCellSize::default(),
+            2,
+            RenderEncoding::SemanticFrame,
+            None,
+        ),
+    );
+    server.clients.insert(
+        2,
+        ClientConnection::new_with_mode(
+            ClientConnectionMode::TerminalPending,
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::TerminalAnsi,
+            None,
+        ),
+    );
+    server.foreground_client_id = Some(1);
+    server.resize_shared_runtime_to_effective_size();
+    let shell_size = server.effective_size;
+
+    assert!(server.handle_server_event(ServerEvent::ClientResize {
+        client_id: 2,
+        cols: 200,
+        rows: 60,
+        cell_width_px: 10,
+        cell_height_px: 20,
+        pixel_mouse: false,
+    }));
+
+    assert_eq!(server.foreground_client_id, Some(1));
+    assert_eq!(server.effective_size, shell_size);
+    assert_eq!(server.clients[&2].terminal_size, (200, 60));
+}
+
+#[test]
+fn client_shell_streams_focused_pane_report_all_demand() {
+    with_terminal_session_test_server(|server, _other_terminal_id, terminal_id, _pane_id| {
+        let (client_tx, client_control_rx, _client_rx) = test_client_writer();
+        server.clients.insert(
+            1,
+            ClientConnection::new(
+                (80, 24),
+                crate::kitty_graphics::HostCellSize::default(),
+                1,
+                RenderEncoding::SemanticFrame,
+                Some(client_tx),
+            ),
+        );
+        server.app.state.active = Some(0);
+        server
+            .runtime_for_terminal_id_string(&terminal_id)
+            .expect("focused runtime")
+            .test_process_pty_bytes(b"\x1b[>15u");
+
+        server.stream_direct_terminal_keyboard_mode();
+
+        assert!(matches!(
+            read_server_message(
+                client_control_rx
+                    .recv_timeout(Duration::from_millis(100))
+                    .expect("shell keyboard mode message")
+            ),
+            ServerMessage::ClientShellKeyboardReportAll { enabled: true }
+        ));
+    });
+}
+
+#[tokio::test]
+async fn client_shell_release_cleanup_does_not_promote_and_survives_disconnect() {
+    let mut server = test_headless_server();
+    let mut input_rx = install_focused_test_runtime(&mut server, b"\x1b[>3u");
+    let pane_id = server.app.session_snapshot().focused_pane_id.unwrap();
+    for client_id in [1, 2] {
+        server.clients.insert(
+            client_id,
+            ClientConnection::new(
+                (80, 24),
+                crate::kitty_graphics::HostCellSize::default(),
+                client_id,
+                RenderEncoding::SemanticFrame,
+                None,
+            ),
+        );
+    }
+    let key = |kind| crate::protocol::ClientPaneInputEvent::Key {
+        code: crate::protocol::ClientKeyCode::Char('x'),
+        modifiers: 0,
+        kind,
+        repeat_count: 1,
+        shifted_codepoint: None,
+        generated_text: (kind == crate::protocol::ClientKeyKind::Press).then(|| "x".to_owned()),
+        tracks_release: true,
+        physical_key_id: Some(0x2d),
+    };
+
+    assert!(
+        server.handle_server_event(ServerEvent::ClientShellPaneInput {
+            client_id: 1,
+            pane_id: pane_id.clone(),
+            events: vec![key(crate::protocol::ClientKeyKind::Press)],
+        })
+    );
+    assert!(!input_rx.recv().await.expect("encoded press").is_empty());
+    assert!(server.promote_client_to_foreground(2));
+
+    assert!(
+        !server.handle_server_event(ServerEvent::ClientShellPaneInput {
+            client_id: 1,
+            pane_id: pane_id.clone(),
+            events: vec![key(crate::protocol::ClientKeyKind::Release)],
+        })
+    );
+    assert!(!input_rx.recv().await.expect("encoded release").is_empty());
+    assert_eq!(server.foreground_client_id, Some(2));
+
+    assert!(
+        server.handle_server_event(ServerEvent::ClientShellPaneInput {
+            client_id: 1,
+            pane_id,
+            events: vec![key(crate::protocol::ClientKeyKind::Press)],
+        })
+    );
+    assert!(!input_rx
+        .recv()
+        .await
+        .expect("second encoded press")
+        .is_empty());
+    assert!(server.handle_server_event(ServerEvent::ClientDisconnected { client_id: 1 }));
+    assert!(!input_rx
+        .recv()
+        .await
+        .expect("disconnect synthesized release")
+        .is_empty());
+    shutdown_test_runtimes(&mut server);
+}
+
+#[test]
+fn client_shell_mouse_capture_combines_local_preference_with_endpoint_demand() {
+    let mut server = test_headless_server();
+    let (writer, control_rx, _render_rx) = test_client_writer();
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            Some(writer),
+        ),
+    );
+
+    server.stream_host_mouse_capture_mode();
+    assert!(matches!(
+        read_server_message(control_rx.recv().expect("initial mouse mode")),
+        ServerMessage::MouseCapture {
+            enabled: false,
+            sgr_pixels: false
+        }
+    ));
+    assert!(
+        server.handle_server_event(ServerEvent::ClientShellMouseCapture {
+            client_id: 1,
+            enabled: true,
+        })
+    );
+    server.stream_host_mouse_capture_mode();
+    assert!(matches!(
+        read_server_message(control_rx.recv().expect("preferred mouse mode")),
+        ServerMessage::MouseCapture {
+            enabled: true,
+            sgr_pixels: false
+        }
+    ));
+}
+
+#[test]
+fn client_shell_focus_promotes_and_reaches_reporting_pane() {
+    with_terminal_session_test_server(|server, terminal_id, _other_terminal_id, _pane_id| {
+        let (runtime, mut input_rx) =
+            crate::terminal::TerminalRuntime::test_with_channel_and_scrollback_bytes(
+                80,
+                24,
+                0,
+                b"\x1b[?1004h",
+                4,
+            );
+        server
+            .app
+            .terminal_runtimes
+            .insert(terminal_id.clone(), runtime);
+        server.app.state.active = Some(0);
+        server.clients.insert(
+            1,
+            ClientConnection::new(
+                (80, 24),
+                crate::kitty_graphics::HostCellSize::default(),
+                1,
+                RenderEncoding::SemanticFrame,
+                None,
+            ),
+        );
+        server.clients.insert(
+            2,
+            ClientConnection::new(
+                (100, 30),
+                crate::kitty_graphics::HostCellSize::default(),
+                2,
+                RenderEncoding::SemanticFrame,
+                None,
+            ),
+        );
+        server.foreground_client_id = Some(2);
+        server.sync_foreground_client_state();
+        server.resize_shared_runtime_to_effective_size();
+        assert_eq!(
+            server
+                .app
+                .terminal_runtimes
+                .get(&terminal_id)
+                .expect("focused runtime")
+                .current_size(),
+            (30, 99)
+        );
+
+        assert!(server.handle_server_event(ServerEvent::ClientShellFocus {
+            client_id: 1,
+            focused: true,
+        }));
+        assert_eq!(server.foreground_client_id, Some(1));
+        assert_eq!(server.app.state.outer_terminal_focus, Some(true));
+        assert_eq!(
+            server
+                .app
+                .terminal_runtimes
+                .get(&terminal_id)
+                .expect("focused runtime")
+                .current_size(),
+            (24, 79)
+        );
+        assert_eq!(
+            input_rx.try_recv().expect("focus gained input"),
+            Bytes::from_static(b"\x1b[I")
+        );
+
+        assert!(server.handle_server_event(ServerEvent::ClientShellFocus {
+            client_id: 1,
+            focused: false,
+        }));
+        assert_eq!(server.app.state.outer_terminal_focus, Some(false));
+        assert_eq!(
+            input_rx.try_recv().expect("focus lost input"),
+            Bytes::from_static(b"\x1b[O")
+        );
+    });
+}
+
+#[test]
+fn direct_terminal_streams_child_keyboard_and_mouse_modes() {
+    with_terminal_session_test_server(|server, _other_terminal_id, terminal_id, _pane_id| {
+        let (client_tx, client_control_rx, _client_rx) = test_client_writer();
+        server.clients.insert(
+            1,
+            ClientConnection::new_with_mode(
+                ClientConnectionMode::TerminalAttach {
+                    terminal_id: terminal_id.clone(),
+                },
+                (80, 24),
+                crate::kitty_graphics::HostCellSize::default(),
+                1,
+                RenderEncoding::TerminalAnsi,
+                Some(client_tx),
+            ),
+        );
+        server
+            .clients
+            .get_mut(&1)
+            .expect("direct attach client")
+            .pixel_mouse = true;
+        server
+            .runtime_for_terminal_id_string(&terminal_id)
+            .expect("attached runtime")
+            .test_process_pty_bytes(b"\x1b[>15u\x1b[?1000h");
+
+        server.stream_direct_terminal_keyboard_mode();
+        assert!(matches!(
+            read_server_message(
+                client_control_rx
+                    .recv_timeout(Duration::from_millis(100))
+                    .expect("keyboard mode message")
+            ),
+            ServerMessage::DirectTerminalKeyboardProtocol {
+                flags: 15,
+                modify_other_keys_level: 0
+            }
+        ));
+
+        server
+            .runtime_for_terminal_id_string(&terminal_id)
+            .expect("attached runtime")
+            .test_process_pty_bytes(b"\x1b[<u\x1b[>3u\x1b[>4;1m");
+        server.stream_direct_terminal_keyboard_mode();
+        assert!(matches!(
+            read_server_message(
+                client_control_rx
+                    .recv_timeout(Duration::from_millis(100))
+                    .expect("modifyOtherKeys mode-one keyboard message")
+            ),
+            ServerMessage::DirectTerminalKeyboardProtocol {
+                flags: 3,
+                modify_other_keys_level: 1
+            }
+        ));
+
+        server
+            .runtime_for_terminal_id_string(&terminal_id)
+            .expect("attached runtime")
+            .test_process_pty_bytes(b"\x1b[>4;2m");
+        server.stream_direct_terminal_keyboard_mode();
+        assert!(matches!(
+            read_server_message(
+                client_control_rx
+                    .recv_timeout(Duration::from_millis(100))
+                    .expect("modifyOtherKeys mode-two keyboard message")
+            ),
+            ServerMessage::DirectTerminalKeyboardProtocol {
+                flags: 3,
+                modify_other_keys_level: 2
+            }
+        ));
+
+        server
+            .runtime_for_terminal_id_string(&terminal_id)
+            .expect("attached runtime")
+            .test_process_pty_bytes(b"\x1b[<u");
+        server.stream_direct_terminal_keyboard_mode();
+        assert!(matches!(
+            read_server_message(
+                client_control_rx
+                    .recv_timeout(Duration::from_millis(100))
+                    .expect("modifyOtherKeys-only keyboard mode message")
+            ),
+            ServerMessage::DirectTerminalKeyboardProtocol {
+                flags: 0,
+                modify_other_keys_level: 2
+            }
+        ));
+
+        server.stream_host_mouse_capture_mode();
+        assert!(matches!(
+            read_server_message(
+                client_control_rx
+                    .recv_timeout(Duration::from_millis(100))
+                    .expect("mouse capture message")
+            ),
+            ServerMessage::MouseCapture {
+                enabled: true,
+                sgr_pixels: false
+            }
+        ));
+
+        server
+            .runtime_for_terminal_id_string(&terminal_id)
+            .expect("attached runtime")
+            .test_process_pty_bytes(b"\x1b[?1016h");
+        server.stream_host_mouse_capture_mode();
+        assert!(matches!(
+            read_server_message(
+                client_control_rx
+                    .recv_timeout(Duration::from_millis(100))
+                    .expect("pixel mouse capture message")
+            ),
+            ServerMessage::MouseCapture {
+                enabled: true,
+                sgr_pixels: true
+            }
+        ));
+
+        server
+            .runtime_for_terminal_id_string(&terminal_id)
+            .expect("attached runtime")
+            .test_process_pty_bytes(b"\x1b[?1000l\x1b[?1016l");
+        server.stream_host_mouse_capture_mode();
+        assert!(matches!(
+            read_server_message(
+                client_control_rx
+                    .recv_timeout(Duration::from_millis(100))
+                    .expect("child mouse disable message")
+            ),
+            ServerMessage::MouseCapture {
+                enabled: false,
+                sgr_pixels: false
+            }
+        ));
+    });
+}
+
+#[test]
+fn direct_terminal_mouse_uses_runtime_protocol_encoding() {
+    with_terminal_session_test_server(|server, runtime_terminal_id, terminal_id, _pane_id| {
+        let (runtime, mut input_rx) =
+            crate::terminal::TerminalRuntime::test_with_channel_and_scrollback_bytes(
+                80,
+                24,
+                0,
+                b"\x1b[?1000h\x1b[?1006h",
+                4,
+            );
+        server
+            .app
+            .terminal_runtimes
+            .insert(runtime_terminal_id, runtime);
+        server.clients.insert(
+            1,
+            ClientConnection::new_with_mode(
+                ClientConnectionMode::TerminalAttach {
+                    terminal_id: terminal_id.clone(),
+                },
+                (80, 24),
+                crate::kitty_graphics::HostCellSize::default(),
+                1,
+                RenderEncoding::TerminalAnsi,
+                None,
+            ),
+        );
+
+        assert!(server.handle_server_event(ServerEvent::ClientAttachMouse {
+            client_id: 1,
+            kind: protocol::ClientMouseKind::Down(protocol::ClientMouseButton::Left),
+            position: protocol::ClientMousePosition::Cell { column: 10, row: 5 },
+            geometry: None,
+            modifiers: 0,
+            lines: 1,
+        }));
+        assert_eq!(
+            input_rx.try_recv().expect("encoded direct mouse input"),
+            Bytes::from_static(b"\x1b[<0;11;6M")
+        );
+    });
+}
+
+#[test]
+fn direct_terminal_pixel_mouse_uses_runtime_tracking_and_coordinates() {
+    with_terminal_session_test_server(|server, runtime_terminal_id, terminal_id, _pane_id| {
+        let (runtime, mut input_rx) =
+            crate::terminal::TerminalRuntime::test_with_channel_and_scrollback_bytes(
+                80,
+                24,
+                0,
+                b"\x1b[?1000h\x1b[?1006h\x1b[?1016h",
+                4,
+            );
+        runtime.resize(24, 80, 10, 20);
+        server
+            .app
+            .terminal_runtimes
+            .insert(runtime_terminal_id, runtime);
+        server.clients.insert(
+            1,
+            ClientConnection::new_with_mode(
+                ClientConnectionMode::TerminalAttach {
+                    terminal_id: terminal_id.clone(),
+                },
+                (80, 24),
+                crate::kitty_graphics::HostCellSize {
+                    width_px: 10,
+                    height_px: 20,
+                },
+                1,
+                RenderEncoding::TerminalAnsi,
+                None,
+            ),
+        );
+        let client = server.clients.get_mut(&1).expect("direct attach client");
+        client.pixel_mouse = true;
+        client.host_sgr_pixels_active = Some(true);
+
+        assert!(!server.handle_server_event(ServerEvent::ClientAttachMouse {
+            client_id: 1,
+            kind: protocol::ClientMouseKind::Down(protocol::ClientMouseButton::Left),
+            position: protocol::ClientMousePosition::Pixels {
+                x: 21,
+                y: 22,
+                column: 3,
+                row: 1,
+            },
+            geometry: Some(protocol::ClientMouseGeometry {
+                cols: 80,
+                rows: 24,
+                width_px: 800,
+                height_px: 480,
+            }),
+            modifiers: 0,
+            lines: 1,
+        }));
+        assert!(input_rx.try_recv().is_err());
+
+        assert!(server.handle_server_event(ServerEvent::ClientAttachMouse {
+            client_id: 1,
+            kind: protocol::ClientMouseKind::Down(protocol::ClientMouseButton::Left),
+            position: protocol::ClientMousePosition::Pixels {
+                x: 21,
+                y: 22,
+                column: 2,
+                row: 1,
+            },
+            geometry: Some(protocol::ClientMouseGeometry {
+                cols: 80,
+                rows: 24,
+                width_px: 805,
+                height_px: 485,
+            }),
+            modifiers: 0,
+            lines: 1,
+        }));
+        assert_eq!(
+            input_rx
+                .try_recv()
+                .expect("proportionally mapped direct pixel mouse input"),
+            Bytes::from_static(b"\x1b[<0;21;22M")
+        );
+
+        assert!(server.handle_server_event(ServerEvent::ClientAttachMouse {
+            client_id: 1,
+            kind: protocol::ClientMouseKind::Moved,
+            position: protocol::ClientMousePosition::Pixels {
+                x: 21,
+                y: 22,
+                column: 2,
+                row: 1,
+            },
+            geometry: Some(protocol::ClientMouseGeometry {
+                cols: 80,
+                rows: 24,
+                width_px: 800,
+                height_px: 480,
+            }),
+            modifiers: 0,
+            lines: 1,
+        }));
+        assert!(input_rx.try_recv().is_err());
+
+        assert!(server.handle_server_event(ServerEvent::ClientAttachMouse {
+            client_id: 1,
+            kind: protocol::ClientMouseKind::Down(protocol::ClientMouseButton::Left),
+            position: protocol::ClientMousePosition::Pixels {
+                x: 21,
+                y: 22,
+                column: 2,
+                row: 1,
+            },
+            geometry: Some(protocol::ClientMouseGeometry {
+                cols: 80,
+                rows: 24,
+                width_px: 800,
+                height_px: 480,
+            }),
+            modifiers: 0,
+            lines: 1,
+        }));
+        assert_eq!(
+            input_rx
+                .try_recv()
+                .expect("encoded direct pixel mouse input"),
+            Bytes::from_static(b"\x1b[<0;21;22M")
+        );
+    });
+}
+
+#[test]
+fn client_config_reload_request_refreshes_attached_clients() {
+    let mut server = test_headless_server();
+    let (client_tx, client_control_rx, _client_rx) = test_client_writer();
+
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            Some(client_tx),
+        ),
+    );
+    server.app.state.request_client_config_reload = true;
+
+    server.drain_client_config_reload_request();
+
+    match read_server_message(
+        client_control_rx
+            .recv_timeout(Duration::from_millis(100))
+            .expect("client config reload message"),
+    ) {
+        ServerMessage::ReloadSoundConfig => {}
+        other => panic!("expected ReloadSoundConfig, got {other:?}"),
+    }
+    assert!(!server.app.state.request_client_config_reload);
+}
+
+#[test]
+fn terminal_bell_targets_foreground_client_only() {
+    let mut server = test_headless_server();
+    let (background_tx, background_control_rx, _background_rx) = test_client_writer();
+    let (foreground_tx, foreground_control_rx, _foreground_rx) = test_client_writer();
+
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (120, 40),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            Some(background_tx),
+        ),
+    );
+    server.clients.insert(
+        2,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            2,
+            RenderEncoding::SemanticFrame,
+            Some(foreground_tx),
+        ),
+    );
+    server.foreground_client_id = Some(2);
+
+    let changed = server.handle_internal_event_with_forwarding(AppEvent::TerminalBell {
+        pane_id: crate::layout::PaneId::from_raw(1),
+        count: 3,
+    });
+
+    assert!(!changed);
+    match read_server_message(
+        foreground_control_rx
+            .recv_timeout(Duration::from_millis(100))
+            .expect("foreground terminal bell message"),
+    ) {
+        ServerMessage::TerminalBell { count } => assert_eq!(count, 3),
+        other => panic!("expected terminal bell message, got {other:?}"),
+    }
+    assert!(
+        background_control_rx
+            .recv_timeout(Duration::from_millis(50))
+            .is_err(),
+        "background client should not receive terminal bells"
+    );
+
+    server.foreground_client_id = None;
+    server.handle_internal_event_with_forwarding(AppEvent::TerminalBell {
+        pane_id: crate::layout::PaneId::from_raw(1),
+        count: 1,
+    });
+    assert!(
+        foreground_control_rx
+            .recv_timeout(Duration::from_millis(50))
+            .is_err(),
+        "bells without a foreground client must not be retained"
+    );
+}
+
+#[test]
+fn clipboard_write_targets_foreground_client_only() {
+    let mut server = test_headless_server();
+    let (background_tx, background_control_rx, _background_rx) = test_client_writer();
+    let (foreground_tx, foreground_control_rx, _foreground_rx) = test_client_writer();
+
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (120, 40),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            Some(background_tx),
+        ),
+    );
+    server.clients.insert(
+        2,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            2,
+            RenderEncoding::SemanticFrame,
+            Some(foreground_tx),
+        ),
+    );
+    server.foreground_client_id = Some(2);
+    server.sync_foreground_client_state();
+
+    let changed = server.handle_internal_event_with_forwarding(AppEvent::ClipboardWrite {
+        content: b"test".to_vec(),
+    });
+
+    assert!(!changed);
+    match read_server_message(
+        foreground_control_rx
+            .recv_timeout(Duration::from_millis(100))
+            .expect("foreground clipboard message"),
+    ) {
+        ServerMessage::Clipboard { data } => assert_eq!(data, "dGVzdA=="),
+        other => panic!("expected clipboard message, got {other:?}"),
+    }
+    assert!(
+        background_control_rx
+            .recv_timeout(Duration::from_millis(50))
+            .is_err(),
+        "background client should not receive clipboard writes"
+    );
+}
+
+#[test]
+fn clipboard_write_without_foreground_client_does_not_change_visual_state() {
+    let mut server = test_headless_server();
+    server.foreground_client_id = None;
+
+    let changed = server.handle_internal_event_with_forwarding(AppEvent::ClipboardWrite {
+        content: b"test".to_vec(),
+    });
+
+    assert!(!changed);
+}
+
+#[test]
+fn clipboard_write_failed_foreground_send_removes_client_without_visual_change() {
+    let mut server = test_headless_server();
+    let (foreground_tx, foreground_control_rx, _foreground_rx) = test_client_writer();
+    drop(foreground_control_rx);
+    foreground_tx.test_close();
+
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            Some(foreground_tx),
+        ),
+    );
+    server.foreground_client_id = Some(1);
+
+    let changed = server.handle_internal_event_with_forwarding(AppEvent::ClipboardWrite {
+        content: b"test".to_vec(),
+    });
+
+    assert!(!changed);
+    assert!(
+        !server.clients.contains_key(&1),
+        "failed targeted send should remove the broken foreground client"
+    );
+}
+
+#[test]
+fn semantic_notifications_broadcast_only_to_client_shells() {
+    let mut server = test_headless_server();
+    let (shell_one_tx, shell_one_control, _shell_one_frames) = test_client_writer();
+    let (shell_two_tx, shell_two_control, _shell_two_frames) = test_client_writer();
+    let (terminal_tx, terminal_control, _terminal_frames) = test_client_writer();
+    for (client_id, writer) in [(1, shell_one_tx), (2, shell_two_tx)] {
+        server.clients.insert(
+            client_id,
+            ClientConnection::new_with_mode(
+                ClientConnectionMode::ClientShell,
+                (80, 24),
+                crate::kitty_graphics::HostCellSize::default(),
+                client_id,
+                RenderEncoding::SemanticFrame,
+                Some(writer),
+            ),
+        );
+    }
+    server.clients.insert(
+        3,
+        ClientConnection::new_with_mode(
+            ClientConnectionMode::TerminalPending,
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            3,
+            RenderEncoding::TerminalAnsi,
+            Some(terminal_tx),
+        ),
+    );
+    let event = protocol::SemanticNotification {
+        kind: protocol::SemanticNotificationKind::Custom,
+        title: "hello".into(),
+        body: None,
+        sound: None,
+        agent: None,
+        workspace_id: None,
+        tab_id: None,
+        pane_id: None,
+        position: None,
+    };
+    assert!(server.send_to_client_shells(ServerMessage::SemanticNotification(event.clone())));
+    for receiver in [shell_one_control, shell_two_control] {
+        assert_eq!(
+            read_server_message(
+                receiver
+                    .recv_timeout(Duration::from_millis(100))
+                    .expect("semantic notification")
+            ),
+            ServerMessage::SemanticNotification(event.clone())
+        );
+    }
+    assert!(terminal_control
+        .recv_timeout(Duration::from_millis(50))
+        .is_err());
+}
+
+#[test]
+fn notification_show_uses_client_shell_policy_independent_of_server_delivery() {
+    let mut server = test_headless_server();
+    server.app.state.toast_config.delivery = config::ToastDelivery::Off;
+    let (shell_tx, shell_control, _shell_frames) = test_client_writer();
+    server.clients.insert(
+        1,
+        ClientConnection::new_with_mode(
+            ClientConnectionMode::ClientShell,
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            Some(shell_tx),
+        ),
+    );
+    let response = server.handle_notification_show_api(
+        "notify-shell".into(),
+        api::schema::NotificationShowParams {
+            title: "plugin title".into(),
+            body: Some("plugin body".into()),
+            position: Some(crate::config::ToastHerdrPosition::TopLeft),
+            sound: api::schema::NotificationShowSound::Done,
+        },
+    );
+    let response: api::schema::SuccessResponse = serde_json::from_str(&response).unwrap();
+    assert!(matches!(
+        response.result,
+        api::schema::ResponseResult::NotificationShow { shown: true, .. }
+    ));
+    assert_eq!(
+        read_server_message(
+            shell_control
+                .recv_timeout(Duration::from_millis(100))
+                .expect("semantic plugin notification")
+        ),
+        ServerMessage::SemanticNotification(protocol::SemanticNotification {
+            kind: protocol::SemanticNotificationKind::Custom,
+            title: "plugin title".into(),
+            body: Some("plugin body".into()),
+            sound: Some(protocol::SemanticNotificationSound::Done),
+            agent: None,
+            workspace_id: None,
+            tab_id: None,
+            pane_id: None,
+            position: Some(crate::config::ToastHerdrPosition::TopLeft),
+        })
+    );
+}
+
+#[test]
+fn client_local_notifications_target_foreground_client_only() {
+    let mut server = test_headless_server();
+    let (background_tx, background_control_rx, _background_rx) = test_client_writer();
+    let (foreground_tx, foreground_control_rx, _foreground_rx) = test_client_writer();
+
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (120, 40),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            Some(background_tx),
+        ),
+    );
+    server.clients.insert(
+        2,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            2,
+            RenderEncoding::SemanticFrame,
+            Some(foreground_tx),
+        ),
+    );
+    server.foreground_client_id = Some(2);
+    server.sync_foreground_client_state();
+
+    assert!(server.send_to_foreground_client(ServerMessage::Notify {
+        kind: protocol::NotifyKind::Toast,
+        message: "pi finished".to_string(),
+        body: Some("workspace 1".to_string()),
+    }));
+
+    match read_server_message(
+        foreground_control_rx
+            .recv_timeout(Duration::from_millis(100))
+            .expect("foreground toast message"),
+    ) {
+        ServerMessage::Notify {
+            kind,
+            message,
+            body,
+        } => {
+            assert_eq!(kind, protocol::NotifyKind::Toast);
+            assert_eq!(message, "pi finished");
+            assert_eq!(body.as_deref(), Some("workspace 1"));
+        }
+        other => panic!("expected toast notify, got {other:?}"),
+    }
+    assert!(
+        background_control_rx
+            .recv_timeout(Duration::from_millis(50))
+            .is_err(),
+        "background client should not receive client-local notifications"
+    );
+}
+
+#[test]
+fn oversized_paste_rejection_notifies_only_the_sending_client() {
+    let mut server = test_headless_server();
+    let (sender_writer, sender_control_rx, _sender_render_rx) = test_client_writer();
+    let (foreground_writer, foreground_control_rx, _foreground_render_rx) = test_client_writer();
+
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (120, 40),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            Some(sender_writer),
+        ),
+    );
+    server.clients.insert(
+        2,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            2,
+            RenderEncoding::SemanticFrame,
+            Some(foreground_writer),
+        ),
+    );
+    server.foreground_client_id = Some(2);
+    server.sync_foreground_client_state();
+
+    assert!(
+        !server.handle_server_event(ServerEvent::ClientPasteRejected {
+            client_id: 1,
+            size: 5_000_012,
+            max: 1_048_576,
+        })
+    );
+
+    match read_server_message(
+        sender_control_rx
+            .recv_timeout(Duration::from_millis(100))
+            .expect("sending client rejection notification"),
+    ) {
+        ServerMessage::ClientShellError { message } => assert_eq!(
+            message,
+            "Paste rejected: Input message is 5000012 bytes; Herdr's limit is 1048576 bytes"
+        ),
+        other => panic!("expected client shell paste error, got {other:?}"),
+    }
+    let (shell_writer, shell_control_rx, _shell_render_rx) = test_client_writer();
+    server.clients.insert(
+        3,
+        ClientConnection::new_with_mode(
+            ClientConnectionMode::ClientShell,
+            (100, 30),
+            crate::kitty_graphics::HostCellSize::default(),
+            3,
+            RenderEncoding::SemanticFrame,
+            Some(shell_writer),
+        ),
+    );
+    assert!(
+        !server.handle_server_event(ServerEvent::ClientPasteRejected {
+            client_id: 3,
+            size: 7_000_000,
+            max: 1_048_576,
+        })
+    );
+    match read_server_message(
+        shell_control_rx
+            .recv_timeout(Duration::from_millis(100))
+            .expect("client shell rejection error"),
+    ) {
+        ServerMessage::ClientShellError { message } => assert_eq!(
+            message,
+            "Paste rejected: Input message is 7000000 bytes; Herdr's limit is 1048576 bytes"
+        ),
+        other => panic!("expected client shell paste error, got {other:?}"),
+    }
+    assert!(
+        foreground_control_rx
+            .recv_timeout(Duration::from_millis(50))
+            .is_err(),
+        "foreground client must not receive another client's rejection"
+    );
+    assert_eq!(server.foreground_client_id, Some(2));
+    assert_eq!(server.clients.len(), 3);
+    assert!(server.app.state.toast.is_none());
+}
+
+#[test]
+fn update_notification_reaches_client_shell_independent_of_delivery() {
+    let mut server = test_headless_server();
+    let (client_tx, client_control_rx, _client_rx) = test_client_writer();
+
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            Some(client_tx),
+        ),
+    );
+    server.foreground_client_id = Some(1);
+    server.app.state.toast_config.delivery = crate::config::ToastDelivery::Herdr;
+
+    let changed = server.handle_internal_event_with_forwarding(AppEvent::UpdateReady {
+        version: "9.9.9".to_string(),
+        install_command: "herdr update".into(),
+    });
+
+    assert!(changed);
+    assert!(matches!(
+        read_server_message(
+            client_control_rx
+                .recv_timeout(Duration::from_millis(100))
+                .expect("semantic update notification")
+        ),
+        ServerMessage::SemanticNotification(protocol::SemanticNotification {
+            kind: protocol::SemanticNotificationKind::UpdateInstalled,
+            ..
+        })
+    ));
+}
+
+#[test]
+fn update_notification_is_semantic_for_system_delivery() {
+    let mut server = test_headless_server();
+    let (client_tx, client_control_rx, _client_rx) = test_client_writer();
+
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            Some(client_tx),
+        ),
+    );
+    server.foreground_client_id = Some(1);
+    server.app.state.toast_config.delivery = crate::config::ToastDelivery::System;
+
+    let changed = server.handle_internal_event_with_forwarding(AppEvent::UpdateReady {
+        version: "9.9.9".to_string(),
+        install_command: "herdr update".into(),
+    });
+
+    assert!(changed);
+    match read_server_message(
+        client_control_rx
+            .recv_timeout(Duration::from_millis(100))
+            .expect("semantic update notification"),
+    ) {
+        ServerMessage::SemanticNotification(notification) => {
+            assert_eq!(
+                notification.kind,
+                protocol::SemanticNotificationKind::UpdateInstalled
+            );
+            assert_eq!(notification.title, "Herdr v9.9.9 available");
+            assert_eq!(
+                notification.body.as_deref(),
+                Some("detach, run `herdr update`, then follow its restart guidance")
+            );
+        }
+        other => panic!("expected semantic update notification, got {other:?}"),
+    }
+}
+
+#[test]
+fn notification_show_api_forwards_one_semantic_client_notification() {
+    let mut server = test_headless_server();
+    let (client_tx, client_control_rx, _client_rx) = test_client_writer();
+
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            Some(client_tx),
+        ),
+    );
+    server.foreground_client_id = Some(1);
+    server.app.state.toast_config.delivery = crate::config::ToastDelivery::System;
+
+    let (respond_to, response_rx) = std::sync::mpsc::channel();
+    let changed = server.handle_api_request_with_shutdown_check(api::ApiRequestMessage {
+        request: api::schema::Request {
+            id: "notify".into(),
+            method: api::schema::Method::NotificationShow(api::schema::NotificationShowParams {
+                title: "build failed".into(),
+                body: Some("api workspace".into()),
+                position: Some(crate::config::ToastHerdrPosition::TopLeft),
+                sound: api::schema::NotificationShowSound::Request,
+            }),
+        },
+        respond_to,
+        response_write_complete: None,
+        stream_active: None,
+    });
+
+    assert!(changed);
+    let response = response_rx
+        .recv_timeout(Duration::from_millis(100))
+        .unwrap();
+    let parsed: api::schema::SuccessResponse = serde_json::from_str(&response).unwrap();
+    assert_eq!(
+        parsed.result,
+        api::schema::ResponseResult::NotificationShow {
+            shown: true,
+            reason: api::schema::NotificationShowReason::Shown,
+        }
+    );
+    match read_server_message(
+        client_control_rx
+            .recv_timeout(Duration::from_millis(100))
+            .expect("semantic api notification"),
+    ) {
+        ServerMessage::SemanticNotification(notification) => {
+            assert_eq!(notification.title, "build failed");
+            assert_eq!(notification.body.as_deref(), Some("api workspace"));
+            assert_eq!(
+                notification.sound,
+                Some(protocol::SemanticNotificationSound::Request)
+            );
+        }
+        other => panic!("expected semantic api notification, got {other:?}"),
+    }
+}
+
+#[test]
+fn notification_show_api_preserves_colon_in_forwarded_title() {
+    let mut server = test_headless_server();
+    let (client_tx, client_control_rx, _client_rx) = test_client_writer();
+
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            Some(client_tx),
+        ),
+    );
+    server.foreground_client_id = Some(1);
+    server.app.state.toast_config.delivery = crate::config::ToastDelivery::System;
+
+    let (respond_to, response_rx) = std::sync::mpsc::channel();
+    let changed = server.handle_api_request_with_shutdown_check(api::ApiRequestMessage {
+        request: api::schema::Request {
+            id: "notify".into(),
+            method: api::schema::Method::NotificationShow(api::schema::NotificationShowParams {
+                title: "build: failed".into(),
+                body: Some("api workspace".into()),
+                position: None,
+                sound: api::schema::NotificationShowSound::None,
+            }),
+        },
+        respond_to,
+        response_write_complete: None,
+        stream_active: None,
+    });
+
+    assert!(changed);
+    let response = response_rx
+        .recv_timeout(Duration::from_millis(100))
+        .unwrap();
+    let parsed: api::schema::SuccessResponse = serde_json::from_str(&response).unwrap();
+    assert_eq!(
+        parsed.result,
+        api::schema::ResponseResult::NotificationShow {
+            shown: true,
+            reason: api::schema::NotificationShowReason::Shown,
+        }
+    );
+    match read_server_message(
+        client_control_rx
+            .recv_timeout(Duration::from_millis(100))
+            .expect("semantic api notification"),
+    ) {
+        ServerMessage::SemanticNotification(notification) => {
+            assert_eq!(notification.title, "build: failed");
+            assert_eq!(notification.body.as_deref(), Some("api workspace"));
+        }
+        other => panic!("expected semantic api notification, got {other:?}"),
+    }
+}
+
+#[test]
+fn notification_show_api_validates_empty_title_before_disabled_delivery() {
+    let mut server = test_headless_server();
+    server.app.state.toast_config.delivery = crate::config::ToastDelivery::Off;
+
+    let (respond_to, response_rx) = std::sync::mpsc::channel();
+    let changed = server.handle_api_request_with_shutdown_check(api::ApiRequestMessage {
+        request: api::schema::Request {
+            id: "notify".into(),
+            method: api::schema::Method::NotificationShow(api::schema::NotificationShowParams {
+                title: "\n\t".into(),
+                body: None,
+                position: None,
+                sound: api::schema::NotificationShowSound::None,
+            }),
+        },
+        respond_to,
+        response_write_complete: None,
+        stream_active: None,
+    });
+
+    assert!(changed);
+    let response = response_rx
+        .recv_timeout(Duration::from_millis(100))
+        .unwrap();
+    let parsed: api::schema::ErrorResponse = serde_json::from_str(&response).unwrap();
+    assert_eq!(parsed.error.code, "invalid_params");
+    assert_eq!(parsed.error.message, "notification title is empty");
+}
+
+#[test]
+fn notification_show_api_reports_no_foreground_client() {
+    let mut server = test_headless_server();
+    server.foreground_client_id = None;
+    server.app.state.toast_config.delivery = crate::config::ToastDelivery::System;
+
+    let (respond_to, response_rx) = std::sync::mpsc::channel();
+    let changed = server.handle_api_request_with_shutdown_check(api::ApiRequestMessage {
+        request: api::schema::Request {
+            id: "notify".into(),
+            method: api::schema::Method::NotificationShow(api::schema::NotificationShowParams {
+                title: "build failed".into(),
+                body: None,
+                position: None,
+                sound: api::schema::NotificationShowSound::Request,
+            }),
+        },
+        respond_to,
+        response_write_complete: None,
+        stream_active: None,
+    });
+
+    assert!(changed);
+    let response = response_rx
+        .recv_timeout(Duration::from_millis(100))
+        .unwrap();
+    let parsed: api::schema::SuccessResponse = serde_json::from_str(&response).unwrap();
+    assert_eq!(
+        parsed.result,
+        api::schema::ResponseResult::NotificationShow {
+            shown: false,
+            reason: api::schema::NotificationShowReason::NoForegroundClient,
+        }
+    );
+}
+
+#[test]
+fn notification_show_api_includes_sound_in_semantic_event() {
+    let mut server = test_headless_server();
+    let (client_tx, client_control_rx, _client_rx) = test_client_writer();
+
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            Some(client_tx),
+        ),
+    );
+    server.foreground_client_id = Some(1);
+    server.app.state.toast_config.delivery = crate::config::ToastDelivery::Herdr;
+
+    let (respond_to, response_rx) = std::sync::mpsc::channel();
+    assert!(
+        server.handle_api_request_with_shutdown_check(api::ApiRequestMessage {
+            request: api::schema::Request {
+                id: "notify".into(),
+                method: api::schema::Method::NotificationShow(
+                    api::schema::NotificationShowParams {
+                        title: "build failed".into(),
+                        body: None,
+                        position: None,
+                        sound: api::schema::NotificationShowSound::Done,
+                    },
+                ),
+            },
+            respond_to,
+            response_write_complete: None,
+            stream_active: None,
+        })
+    );
+
+    let response = response_rx
+        .recv_timeout(Duration::from_millis(100))
+        .unwrap();
+    let parsed: api::schema::SuccessResponse = serde_json::from_str(&response).unwrap();
+    assert_eq!(
+        parsed.result,
+        api::schema::ResponseResult::NotificationShow {
+            shown: true,
+            reason: api::schema::NotificationShowReason::Shown,
+        }
+    );
+    match read_server_message(
+        client_control_rx
+            .recv_timeout(Duration::from_millis(100))
+            .expect("semantic api notification"),
+    ) {
+        ServerMessage::SemanticNotification(notification) => {
+            assert_eq!(notification.title, "build failed");
+            assert_eq!(
+                notification.sound,
+                Some(protocol::SemanticNotificationSound::Done)
+            );
+        }
+        other => panic!("expected semantic api notification, got {other:?}"),
+    }
+}
+
+#[test]
+fn startup_idle_does_not_forward_completion() {
+    let mut server = test_headless_server();
+    let workspace = crate::workspace::Workspace::test_new("active");
+    let pane_id = workspace.tabs[0].root_pane;
+    server.app.state.workspaces = vec![workspace];
+    server.app.state.ensure_test_terminals();
+    server.app.state.active = Some(0);
+    server.app.state.toast_config.delivery = crate::config::ToastDelivery::System;
+    server.app.state.toast_config.delay_seconds = 0;
+    server.app.state.sound.enabled = true;
+
+    assert!(
+        server.handle_internal_event_with_forwarding(AppEvent::AgentProcessDetected {
+            pane_id,
+            agent: crate::detect::Agent::Pi,
+            observed_at: Instant::now(),
+        })
+    );
+
+    let (client_tx, client_control_rx, _client_rx) = test_client_writer();
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            Some(client_tx),
+        ),
+    );
+    server.foreground_client_id = Some(1);
+    server.sync_foreground_client_state();
+    while client_control_rx
+        .recv_timeout(Duration::from_millis(20))
+        .is_ok()
+    {}
+
+    assert!(
+        server.handle_internal_event_with_forwarding(AppEvent::StateChanged {
+            pane_id,
+            agent: Some(crate::detect::Agent::Pi),
+            state: crate::detect::AgentState::Idle,
+            visible_blocker: false,
+            visible_working: false,
+            process_exited: false,
+            observed_at: Instant::now(),
+        })
+    );
+    assert!(
+        client_control_rx
+            .recv_timeout(Duration::from_millis(50))
+            .is_err(),
+        "startup readiness should not forward a completion notification"
+    );
+}
+
+#[test]
+fn stale_api_agent_report_does_not_forward_done_sound() {
+    let mut server = test_headless_server();
+    let background = crate::workspace::Workspace::test_new("background");
+    let pane_id = background.tabs[0].root_pane;
+    let public_pane_id = format!("{}:p1", background.id);
+    let foreground = crate::workspace::Workspace::test_new("foreground");
+    server.app.state.workspaces = vec![background, foreground];
+    server.app.state.ensure_test_terminals();
+    let terminal_id = server.app.state.workspaces[0]
+        .pane_state(pane_id)
+        .unwrap()
+        .attached_terminal_id
+        .clone();
+    server
+        .app
+        .state
+        .terminals
+        .get_mut(&terminal_id)
+        .unwrap()
+        .set_detected_state(
+            Some(crate::detect::Agent::Pi),
+            crate::detect::AgentState::Idle,
+        );
+    server
+        .app
+        .state
+        .terminals
+        .get_mut(&terminal_id)
+        .unwrap()
+        .set_persisted_agent_session(crate::agent_resume::PersistedAgentSession {
+            source: "herdr:pi".into(),
+            agent: "pi".into(),
+            session_ref: crate::agent_resume::AgentSessionRef::path(
+                std::env::current_dir()
+                    .unwrap()
+                    .join("headless-pi-session.jsonl")
+                    .display()
+                    .to_string(),
+            )
+            .unwrap(),
+        });
+    server
+        .app
+        .state
+        .terminals
+        .get_mut(&terminal_id)
+        .unwrap()
+        .set_hook_authority(
+            "herdr:pi".into(),
+            "pi".into(),
+            crate::detect::AgentState::Working,
+            None,
+            Some(20),
+        );
+    server.app.state.active = Some(1);
+    server.app.state.selected = 1;
+    server.app.state.mode = crate::app::Mode::Terminal;
+
+    let (client_tx, client_control_rx, _client_rx) = test_client_writer();
+    server.clients.insert(
+        1,
+        ClientConnection::new(
+            (80, 24),
+            crate::kitty_graphics::HostCellSize::default(),
+            1,
+            RenderEncoding::SemanticFrame,
+            Some(client_tx),
+        ),
+    );
+    server.foreground_client_id = Some(1);
+    server.sync_foreground_client_state();
+
+    let (respond_to, response_rx) = std::sync::mpsc::channel();
+    let changed = server.handle_api_request_with_shutdown_check(api::ApiRequestMessage {
+        request: api::schema::Request {
+            id: "stale".into(),
+            method: api::schema::Method::PaneReportAgent(api::schema::PaneReportAgentParams {
+                pane_id: public_pane_id,
+                source: "herdr:pi".into(),
+                agent: "pi".into(),
+                state: api::schema::PaneAgentState::Idle,
+                message: None,
+                seq: Some(19),
+                agent_session_id: None,
+                agent_session_path: None,
+            }),
+        },
+        respond_to,
+        response_write_complete: None,
+        stream_active: None,
+    });
+
+    assert!(changed);
+    assert!(response_rx.recv_timeout(Duration::from_millis(100)).is_ok());
+    assert_eq!(
+        server.app.state.terminals.get(&terminal_id).unwrap().state,
+        crate::detect::AgentState::Working
+    );
+    assert!(
+        client_control_rx
+            .recv_timeout(Duration::from_millis(50))
+            .is_err(),
+        "stale idle report must not forward a done sound"
+    );
+}
+
+/// Verify that calls to the app's internal-event methods only occur inside
+/// `handle_internal_event_with_forwarding`. This ensures the forwarding
+/// bypass cannot be reintroduced.
+#[test]
+fn no_handle_internal_event_bypass_in_module() {
+    let source = include_str!("../../headless.rs");
+
+    // Find all lines containing handle_internal_event
+    let mut bypass_lines: Vec<String> = Vec::new();
+    let mut inside_forwarding_method = false;
+    let mut forwarding_method_brace_depth = 0u32;
+
+    for (i, line) in source.lines().enumerate() {
+        let line_num = i + 1;
+
+        // Track when we're inside handle_internal_event_with_forwarding
+        if line.contains("fn handle_internal_event_with_forwarding") {
+            inside_forwarding_method = true;
+            forwarding_method_brace_depth = 0;
+        }
+
+        if inside_forwarding_method {
+            // Count braces to track when we exit the method
+            for ch in line.chars() {
+                match ch {
+                    '{' => forwarding_method_brace_depth += 1,
+                    '}' => {
+                        forwarding_method_brace_depth =
+                            forwarding_method_brace_depth.saturating_sub(1);
+                        if forwarding_method_brace_depth == 0 {
+                            inside_forwarding_method = false;
+                        }
+                    }
+                    _ => {}
+                }
+            }
+        } else if (line.contains("self.app.handle_internal_event(")
+            || line.contains("self.app.handle_internal_event_with_render_impact("))
+            && !line.trim().starts_with("///")
+            && !line.contains("contains(")
+        {
+            // Internal-event call outside the forwarding method.
+            bypass_lines.push(format!("line {}: {}", line_num, line.trim()));
+        }
+    }
+
+    assert!(
+        bypass_lines.is_empty(),
+        "Found direct calls to self.app.handle_internal_event outside \
+             handle_internal_event_with_forwarding (bypass risk):\n  {}",
+        bypass_lines.join("\n  ")
+    );
+}