Scroll to the focused preference from its unscrolled position

src/app.rs

@@ -133,6 +133,10 @@ pub(crate) enum Message {
     WindowOpened(window::Id),
     WindowClosed(window::Id),
     DismissPanel,
+    /// Tab and shift-tab: iced leaves the key to the application, so the fields
+    /// of a form are only linked once we move the focus ourselves.
+    FocusNext,
+    FocusPrevious,
     PreferenceModelChanged(ModelChoice),
     PreferenceDsparkChanged(bool),
     PreferenceTimeoutChanged(String),
@@ -447,6 +451,10 @@ impl App {
                     self.error = None;
                 }
             }
+            Message::FocusNext => return iced::widget::focus_next().chain(reveal_focused()),
+            Message::FocusPrevious => {
+                return iced::widget::focus_previous().chain(reveal_focused());
+            }
             Message::ShowChat => self.detail_tab = DetailTab::Chat,
             Message::ShowStats => {
                 self.detail_tab = DetailTab::Stats;
@@ -1005,6 +1013,18 @@ impl App {
     pub(crate) fn subscription(&self) -> Subscription<Message> {
         let mut subscriptions = vec![
             keyboard::on_key_press(shortcut),
+            // A focused text field takes escape for itself to drop its own
+            // focus, so a dialog would never see it through `on_key_press`.
+            iced::event::listen_with(|event, _, _| {
+                matches!(
+                    event,
+                    iced::Event::Keyboard(keyboard::Event::KeyPressed {
+                        key: keyboard::Key::Named(keyboard::key::Named::Escape),
+                        ..
+                    })
+                )
+                .then_some(Message::DismissPanel)
+            }),
             window::close_requests().map(Message::WindowClosed),
             window::close_events().map(Message::WindowClosed),
         ];
@@ -1199,7 +1219,11 @@ fn shortcut(key: keyboard::Key, modifiers: keyboard::Modifiers) -> Option<Messag
         keyboard::Key::Character("m") if modifiers.command() && modifiers.shift() => {
             Some(Message::OpenModelManager)
         }
-        keyboard::Key::Named(keyboard::key::Named::Escape) => Some(Message::DismissPanel),
+        keyboard::Key::Named(keyboard::key::Named::Tab) => Some(if modifiers.shift() {
+            Message::FocusPrevious
+        } else {
+            Message::FocusNext
+        }),
         _ => None,
     }
 }
@@ -1230,6 +1254,116 @@ pub(super) fn composer_id() -> text_input::Id {
     text_input::Id::new("chat-composer")
 }
 
+pub(super) fn preferences_scroll_id() -> scrollable::Id {
+    scrollable::Id::new("preferences-fields")
+}
+
+/// Scrolls the preferences form so the field that just took focus is inside
+/// the viewport. Iced moves focus without touching the scroll offset, so a tab
+/// past the fold would otherwise send the typing to a field nobody can see.
+///
+/// The focus callback carries no bounds, so the position is taken from the
+/// innermost container around the focused widget — the row that holds the
+/// label and its input.
+fn reveal_focused() -> Task<Message> {
+    use iced::advanced::widget::{Id, Operation, operation};
+    use iced::{Rectangle, Vector};
+
+    struct Locate {
+        rows: Vec<Rectangle>,
+        focused: Option<Rectangle>,
+    }
+
+    impl<T> Operation<T> for Locate {
+        fn container(
+            &mut self,
+            _id: Option<&Id>,
+            bounds: Rectangle,
+            operate_on_children: &mut dyn FnMut(&mut dyn Operation<T>),
+        ) {
+            self.rows.push(bounds);
+            operate_on_children(self);
+            self.rows.pop();
+        }
+
+        fn focusable(&mut self, state: &mut dyn operation::Focusable, _id: Option<&Id>) {
+            if state.is_focused() {
+                self.focused = self.rows.last().copied();
+            }
+        }
+
+        fn finish(&self) -> operation::Outcome<T> {
+            self.focused.map_or(operation::Outcome::None, |field| {
+                operation::Outcome::Chain(Box::new(Reveal { field }))
+            })
+        }
+    }
+
+    struct Reveal {
+        field: Rectangle,
+    }
+
+    impl<T> Operation<T> for Reveal {
+        fn container(
+            &mut self,
+            _id: Option<&Id>,
+            _bounds: Rectangle,
+            operate_on_children: &mut dyn FnMut(&mut dyn Operation<T>),
+        ) {
+            operate_on_children(self);
+        }
+
+        fn scrollable(
+            &mut self,
+            state: &mut dyn operation::Scrollable,
+            id: Option<&Id>,
+            bounds: Rectangle,
+            content_bounds: Rectangle,
+            translation: Vector,
+        ) {
+            if id != Some(&Id::from(preferences_scroll_id())) {
+                return;
+            }
+            let Some(offset) = reveal_offset(self.field, bounds, translation.y) else {
+                return;
+            };
+            state.scroll_by(
+                scrollable::AbsoluteOffset { x: 0.0, y: offset },
+                bounds,
+                content_bounds,
+            );
+        }
+    }
+
+    iced::advanced::widget::operate(Locate {
+        rows: Vec::new(),
+        focused: None,
+    })
+}
+
+/// How far the scroll area has to move for `field` to sit fully inside
+/// `viewport`, or `None` when it already does. A field taller than the viewport
+/// lines up with its top edge.
+///
+/// Layout places the content in its own unscrolled coordinates, so `field` only
+/// says where it sits once `scrolled` — the offset the area is already at — is
+/// taken off it.
+fn reveal_offset(field: iced::Rectangle, viewport: iced::Rectangle, scrolled: f32) -> Option<f32> {
+    // Keep a row's worth of margin, so a revealed field never sits flush
+    // against the edge of the viewport.
+    const MARGIN: f32 = 12.0;
+    let top = field.y - scrolled;
+    let above = top - MARGIN - viewport.y;
+    let below = top + field.height + MARGIN - (viewport.y + viewport.height);
+    if above < 0.0 {
+        Some(above)
+    } else if below > 0.0 {
+        Some(below)
+    } else {
+        None
+    }
+}
+
 fn focus_composer() -> Task<Message> {
     text_input::focus(composer_id())
 }
@@ -1318,11 +1452,45 @@ mod tests {
             keyboard::Modifiers::COMMAND | keyboard::Modifiers::SHIFT,
         );
         assert!(matches!(message, Some(Message::OpenModelManager)));
+        let tab = keyboard::Key::Named(keyboard::key::Named::Tab);
+        assert!(matches!(
+            shortcut(tab.clone(), keyboard::Modifiers::empty()),
+            Some(Message::FocusNext)
+        ));
+        assert!(matches!(
+            shortcut(tab, keyboard::Modifiers::SHIFT),
+            Some(Message::FocusPrevious)
+        ));
         assert!(ModelChoice::DeepSeekV4Flash.supports_dspark());
         assert!(!ModelChoice::DeepSeekV4Pro.supports_dspark());
         assert!(!ModelChoice::Glm52.supports_dspark());
     }
 
+    #[test]
+    fn tab_scrolls_a_field_back_into_the_preferences_viewport() {
+        let viewport = iced::Rectangle {
+            x: 0.0,
+            y: 100.0,
+            width: 700.0,
+            height: 400.0,
+        };
+        let field = |y| iced::Rectangle {
+            x: 0.0,
+            y,
+            width: 700.0,
+            height: 30.0,
+        };
+        assert_eq!(reveal_offset(field(200.0), viewport, 0.0), None);
+        // Above the fold: scroll back by the gap plus the margin.
+        assert_eq!(reveal_offset(field(80.0), viewport, 0.0), Some(-32.0));
+        // Below it: the bottom edge plus the margin comes into view.
+        assert_eq!(reveal_offset(field(490.0), viewport, 0.0), Some(32.0));
+        // A field the scroll already brought into view stays put, and one
+        // further down moves by the gap alone, not by the whole scroll.
+        assert_eq!(reveal_offset(field(690.0), viewport, 500.0), None);
+        assert_eq!(reveal_offset(field(990.0), viewport, 500.0), Some(32.0));
+    }
+
     #[test]
     fn ds4_gib_and_streaming_cache_inputs_are_typed() {
         assert_eq!(

src/app/view.rs

@@ -7,7 +7,7 @@ use model_manager::{download_status_bar, format_bytes, format_duration};
 
 use super::{
     ActiveDownload, App, DetailTab, MAX_SIDEBAR_WIDTH, MIN_SIDEBAR_WIDTH, Message, MetricsPoint,
-    ModelDownload, ModelOperation, chat_scroll_id, composer_id, models_path,
+    ModelDownload, ModelOperation, chat_scroll_id, composer_id, models_path, preferences_scroll_id,
 };
 use crate::database::{ProjectWithSessions, Session, SessionState};
 use crate::model::{
@@ -62,6 +62,15 @@ impl App {
         }
     }
 
+    /// Whether a dialog covers the window. Focus moves through the whole widget
+    /// tree, so the layers below have to stay out of the dialog's field order.
+    pub(super) fn modal_open(&self) -> bool {
+        self.preferences_open
+            || self.pending_project_path.is_some()
+            || self.session_rename.is_some()
+            || self.menu_session().is_some()
+    }
+
     fn main_view(&self) -> Element<'_, Message> {
         let mut body = row![].width(Length::Fill).height(Length::Fill);
         if !self.config.interface.sidebar_collapsed {

src/app/view/chat.rs

@@ -131,12 +131,32 @@ impl App {
                     );
                 }
             }
-            let composer = text_input("Ask DS4Server anything…", &self.composer)
-                .id(composer_id())
-                .on_input(Message::ComposerChanged)
-                .on_submit(Message::SubmitPrompt)
+            // Tab walks every focusable widget of every window, so a composer
+            // left behind an open dialog would take a turn in that dialog's
+            // field order. Behind a modal it becomes a plain look-alike that
+            // cannot be focused; the modal dims it either way.
+            let composer: Element<'_, Message> = if self.modal_open() {
+                container(
+                    text(if self.composer.is_empty() {
+                        "Ask DS4Server anything…"
+                    } else {
+                        &self.composer
+                    })
+                    .size(14)
+                    .color(muted_text()),
+                )
                 .padding(12)
-                .size(14);
+                .width(Length::Fill)
+                .into()
+            } else {
+                text_input("Ask DS4Server anything…", &self.composer)
+                    .id(composer_id())
+                    .on_input(Message::ComposerChanged)
+                    .on_submit(Message::SubmitPrompt)
+                    .padding(12)
+                    .size(14)
+                    .into()
+            };
             let action = if self.generating {
                 action_button(text("Stop").size(12)).on_press(Message::StopGeneration)
             } else if self.composer.trim().is_empty() {

src/app/view/preferences.rs

@@ -563,6 +563,7 @@ impl App {
             column![
                 header,
                 scrollable(container(fields).padding(iced::Padding::ZERO.right(18)))
+                    .id(preferences_scroll_id())
                     .height(Length::Fill),
                 footer
             ]