Add RequestAttention DBus method for tabs needing input

Long-running interactive programs in a tab (notably AI agents) can now
ask the terminal to flag the tab when they need user input. This reuses
the existing tab-state + freedesktop-notification plumbing used for
process completion: a new TabState.ATTENTION shows a
dialog-question-symbolic icon and sets Adw.TabPage.needs_attention,
and the indicator clears when the user focuses the tab.

Triggered from the tab via:

    dbus-send --type=method_call --session \
      --dest=io.elementary.terminal /io/elementary/terminal \
      io.elementary.terminal.RequestAttention \
      string:"$PANTHEON_TERMINAL_ID" string:"reason"

Author: carniz

README.md

@@ -38,3 +38,17 @@ Terminal implements process completion notifications. They are enabled for BASH
     builtin . /usr/share/io.elementary.terminal/enable-zsh-completion-notifications || builtin true
 
 DISTRIBUTORS: depending on the policy of your distribution, either inform the user about this via the default mechanism for your distribution (for DIY distros like Arch), or add that line to `/etc/zshrc` automatically on installation (for preconfigured distros like Ubuntu).
+
+## Attention Requests
+
+Long-running interactive programs (for example AI agents) can ask the terminal to flag a tab when they need user input. The terminal marks the tab with an attention indicator and a `dialog-question-symbolic` icon, and posts a desktop notification if the window is not focused or the tab is not selected. The indicator clears automatically when the user focuses the tab.
+
+Each tab exports its identifier as `PANTHEON_TERMINAL_ID`. A program can request attention with a single DBus call:
+
+    dbus-send --type=method_call --session \
+        --dest=io.elementary.terminal /io/elementary/terminal \
+        io.elementary.terminal.RequestAttention \
+        string:"$PANTHEON_TERMINAL_ID" \
+        string:"Waiting for confirmation"
+
+The second string is shown as the notification body and may be empty.

src/Application.vala

@@ -154,6 +154,53 @@ public class Terminal.Application : Gtk.Application {
         var dbus = new DBus ();
         dbus_id = connection.register_object (object_path, dbus);
 
+        dbus.attention_requested.connect ((id, message) => {
+            TerminalWidget terminal = null;
+
+            foreach (var window in (List<MainWindow>) get_windows ()) {
+                if (terminal != null) {
+                    break;
+                }
+
+                terminal = window.get_terminal (id);
+            }
+
+            if (terminal == null) {
+                return;
+            }
+
+            unowned var window = (MainWindow) terminal.root;
+            if (terminal != window.current_terminal || !window.is_active) {
+                terminal.tab_state = ATTENTION;
+            }
+
+            if (window.is_active && terminal == window.current_terminal) {
+                return;
+            }
+
+            var notification_title = _("Terminal needs your attention");
+            var notification = new Notification (notification_title);
+            if (message.length > 0) {
+                notification.set_body (message);
+            }
+            notification.set_icon (TerminalWidget.TabState.ATTENTION.to_icon ());
+            notification.set_default_action_and_target_value ("app.process-finished", new Variant.string (id));
+            send_notification ("attention-requested-%s".printf (id), notification);
+
+            ulong tab_change_handler = 0;
+            ulong focus_in_handler = 0;
+
+            tab_change_handler = window.notify["current-terminal"].connect ((obj, pspec) => {
+                withdraw_attention_for_terminal ((MainWindow) obj, terminal, id, tab_change_handler, focus_in_handler);
+            });
+
+            focus_in_handler = window.notify["is-active"].connect ((obj, pspec) => {
+                if (((MainWindow) obj).is_active) {
+                    withdraw_attention_for_terminal ((MainWindow) obj, terminal, id, tab_change_handler, focus_in_handler);
+                }
+            });
+        });
+
         dbus.finished_process.connect ((id, process, exit_status) => {
             TerminalWidget terminal = null;
 
@@ -228,6 +275,20 @@ public class Terminal.Application : Gtk.Application {
         window.disconnect (focus_in_handler);
     }
 
+    private void withdraw_attention_for_terminal (MainWindow window, TerminalWidget terminal, string id, ulong tab_change_handler, ulong focus_in_handler) {
+        if (window.current_terminal != terminal) {
+            return;
+        }
+
+        if (terminal.tab_state == ATTENTION) {
+            terminal.tab_state = NONE;
+        }
+        withdraw_notification ("attention-requested-%s".printf (id));
+
+        window.disconnect (tab_change_handler);
+        window.disconnect (focus_in_handler);
+    }
+
     protected override void startup () {
         base.startup ();
         Granite.init ();

src/DBus.vala

@@ -23,11 +23,18 @@ namespace Terminal {
         [DBus (visible = false)]
         public signal void finished_process (string terminal_id, string process, int exit_status);
 
+        [DBus (visible = false)]
+        public signal void attention_requested (string terminal_id, string message);
+
         public DBus () {
         }
 
         public void process_finished (string terminal_id, string process, int exit_status) throws GLib.Error {
             finished_process (terminal_id, process, exit_status);
         }
+
+        public void request_attention (string terminal_id, string message) throws GLib.Error {
+            attention_requested (terminal_id, message);
+        }
     }
 }

src/Widgets/TerminalView.vala

@@ -180,6 +180,7 @@ public class Terminal.TerminalView : Granite.Bin {
 
         terminal_widget.notify["tab-state"].connect (() => {
             tab.icon = terminal_widget.tab_state.to_icon ();
+            tab.needs_attention = terminal_widget.tab_state == ATTENTION;
         });
 
         // Set correct label now to avoid race when spawning shell

src/Widgets/TerminalWidget.vala

@@ -9,7 +9,8 @@ namespace Terminal {
             NONE,
             WORKING,
             COMPLETED,
-            ERROR;
+            ERROR,
+            ATTENTION;
 
             public GLib.Icon? to_icon () {
                 switch (this) {
@@ -18,6 +19,8 @@ namespace Terminal {
                         return new GLib.ThemedIcon ("process-completed-symbolic");
                     case ERROR:
                         return new GLib.ThemedIcon ("process-error-symbolic");
+                    case ATTENTION:
+                        return new GLib.ThemedIcon ("dialog-question-symbolic");
                     default:
                         return null;
                 }