T23c round 1 fix

- suggestions: arrows step past disabled rows and scroll the cursor into view;
  the cursor starts on an enabled row; Enter refuses a disabled one
- active_trigger takes the query's word test: one word for mentions, any
  non-space for the composer, so a file name keeps its dot
- DragDropOverlay takes the drop itself, which gives it the hitbox gpui needs
  to style a drag-over
- ParameterPanel shows the places of the step, value and both ends
- gallery: the prompt menu fills the draft; Reset restores the system prompt
- AGENTS: drag-over styles need a hitbox; debug_bounds never clear

src/chat/tests/compose.rs

@@ -1,19 +1,22 @@
 use gpui::{
-    AppContext as _, Context, Entity, Focusable, IntoElement, ParentElement, Render, SharedString,
-    Styled, TestAppContext, VisualTestContext, Window, div,
+    AppContext as _, Context, Entity, ExternalPaths, FileDropEvent, Focusable, IntoElement,
+    Modifiers, ParentElement, Render, SharedString, Styled, TestAppContext, VisualTestContext,
+    Window, div, point, px,
 };
 
 use super::settle;
 use crate::{
     chat::PromptInput,
     forms::{self, Choice, TextInput},
-    theme::Theme,
+    motion,
+    theme::{ActiveTheme, Theme},
 };
 
 /// A composer over a field, and what it asked: sends, commands and context.
 struct Compose {
     field: Entity<TextInput>,
     busy: bool,
+    commands: Vec<Choice>,
     sent: usize,
     picked: Vec<SharedString>,
 }
@@ -24,13 +27,13 @@ impl Render for Compose {
         let input = PromptInput::new("compose", &self.field, move |_, cx| {
             send.update(cx, |compose, _| compose.sent += 1)
         })
-        .commands(
-            [Choice::new("summarize", "/summarize")],
-            move |value, _, cx| command.update(cx, |compose, _| compose.picked.push(value.clone())),
-        )
+        .commands(self.commands.clone(), move |value, _, cx| {
+            command.update(cx, |compose, _| compose.picked.push(value.clone()))
+        })
         .context([Choice::new("lift", "lift.rs")], move |value, _, cx| {
             mention.update(cx, |compose, _| compose.picked.push(value.clone()))
-        });
+        })
+        .on_drop(|_, _, _| {});
         let input = if self.busy {
             input.busy(|_, _| {})
         } else {
@@ -40,14 +43,20 @@ impl Render for Compose {
     }
 }
 
-fn open(busy: bool, cx: &mut TestAppContext) -> (Entity<Compose>, &mut VisualTestContext) {
+fn open(
+    busy: bool,
+    commands: Vec<Choice>,
+    cx: &mut TestAppContext,
+) -> (Entity<Compose>, &mut VisualTestContext) {
     cx.update(|cx| {
         Theme::init(cx);
+        Theme::update(cx, |theme| theme.reduced_motion = true);
         forms::bind_keys(cx);
     });
     let (compose, cx) = cx.add_window_view(move |window, cx| Compose {
         field: cx.new(|cx| TextInput::new(window, cx).multi_line(1, 8)),
         busy,
+        commands,
         sent: 0,
         picked: Vec::new(),
     });
@@ -60,13 +69,44 @@ fn open(busy: bool, cx: &mut TestAppContext) -> (Entity<Compose>, &mut VisualTes
     (compose, cx)
 }
 
+fn summarize() -> Vec<Choice> {
+    vec![Choice::new("summarize", "/summarize")]
+}
+
+/// Commands `c00` to `c19`, some disabled.
+fn numbered(disabled: &[usize]) -> Vec<Choice> {
+    (0..20)
+        .map(|ix| {
+            let choice = Choice::new(format!("c{ix:02}"), format!("/c{ix:02}"));
+            if disabled.contains(&ix) {
+                choice.disabled()
+            } else {
+                choice
+            }
+        })
+        .collect()
+}
+
+/// Frames 2ms apart, past reduced motion's 1ms entrances.
+fn frames(cx: &mut VisualTestContext) {
+    for _ in 0..3 {
+        std::thread::sleep(std::time::Duration::from_millis(2));
+        cx.update(|window, _| window.refresh());
+        cx.run_until_parked();
+    }
+}
+
+fn picked(compose: &Entity<Compose>, cx: &mut VisualTestContext) -> Vec<SharedString> {
+    compose.read_with(cx, |compose, _| compose.picked.clone())
+}
+
 fn text(compose: &Entity<Compose>, cx: &mut VisualTestContext) -> String {
     cx.update(|_, cx| compose.read(cx).field.read(cx).text().to_string())
 }
 
 #[gpui::test]
 fn enter_sends_and_shift_enter_breaks_the_line(cx: &mut TestAppContext) {
-    let (compose, cx) = open(false, cx);
+    let (compose, cx) = open(false, summarize(), cx);
     cx.simulate_keystrokes("enter");
     assert_eq!(
         compose.read_with(cx, |compose, _| compose.sent),
@@ -90,7 +130,7 @@ fn enter_sends_and_shift_enter_breaks_the_line(cx: &mut TestAppContext) {
 
 #[gpui::test]
 fn a_slash_picks_a_command_and_an_at_sign_picks_context(cx: &mut TestAppContext) {
-    let (compose, cx) = open(false, cx);
+    let (compose, cx) = open(false, summarize(), cx);
     cx.simulate_input("/sum");
     settle(cx);
     cx.simulate_keystrokes("enter");
@@ -109,10 +149,90 @@ fn a_slash_picks_a_command_and_an_at_sign_picks_context(cx: &mut TestAppContext)
 
 #[gpui::test]
 fn a_busy_composer_holds_its_message(cx: &mut TestAppContext) {
-    let (compose, cx) = open(true, cx);
+    let (compose, cx) = open(true, summarize(), cx);
     cx.simulate_input("wait");
     settle(cx);
     cx.simulate_keystrokes("enter");
     assert_eq!(compose.read_with(cx, |compose, _| compose.sent), 0);
     assert_eq!(text(&compose, cx), "wait");
 }
+
+#[gpui::test]
+fn a_file_name_keeps_its_suggestions_past_a_dot(cx: &mut TestAppContext) {
+    let (compose, cx) = open(false, summarize(), cx);
+    cx.simulate_input("see @lift.");
+    settle(cx);
+    cx.simulate_keystrokes("enter");
+    settle(cx);
+    assert_eq!(text(&compose, cx), "see ");
+    assert_eq!(picked(&compose, cx), ["lift"]);
+    assert_eq!(compose.read_with(cx, |compose, _| compose.sent), 0);
+}
+
+#[gpui::test]
+fn arrows_pass_disabled_rows_and_keep_the_cursor_in_view(cx: &mut TestAppContext) {
+    let (compose, cx) = open(false, numbered(&[1]), cx);
+    cx.simulate_input("/");
+    frames(cx);
+    for _ in 0..16 {
+        cx.simulate_keystrokes("down");
+        frames(cx);
+    }
+    let (anchor, height) = cx.update(|window, cx| {
+        let anchor = compose.read(cx).field.read(cx).bounds_for(0);
+        let height = cx.theme().list_max_height().to_pixels(window.rem_size());
+        (anchor.expect("the slash is laid out"), height)
+    });
+    let foot = point(
+        anchor.left() + px(24.0),
+        anchor.bottom() + motion::NUDGE + height - px(8.0),
+    );
+    cx.simulate_mouse_move(foot, None, Modifiers::none());
+    cx.simulate_click(foot, Modifiers::none());
+    assert_eq!(
+        picked(&compose, cx),
+        ["c17"],
+        "sixteen steps past one disabled row land on the eighteenth, at the list's foot"
+    );
+}
+
+#[gpui::test]
+fn the_cursor_starts_on_the_first_enabled_row(cx: &mut TestAppContext) {
+    let (compose, cx) = open(false, numbered(&[0]), cx);
+    cx.simulate_input("/");
+    settle(cx);
+    cx.simulate_keystrokes("enter");
+    settle(cx);
+    assert_eq!(picked(&compose, cx), ["c01"]);
+}
+
+#[gpui::test]
+fn enter_on_only_disabled_rows_picks_and_sends_nothing(cx: &mut TestAppContext) {
+    let (compose, cx) = open(false, vec![Choice::new("c00", "/c00").disabled()], cx);
+    cx.simulate_input("/");
+    settle(cx);
+    cx.simulate_keystrokes("enter");
+    settle(cx);
+    assert_eq!(picked(&compose, cx), Vec::<SharedString>::new());
+    assert_eq!(compose.read_with(cx, |compose, _| compose.sent), 0);
+    assert_eq!(text(&compose, cx), "/");
+}
+
+#[gpui::test]
+fn files_over_the_composer_raise_the_veil(cx: &mut TestAppContext) {
+    let (_, cx) = open(false, summarize(), cx);
+    assert_eq!(
+        cx.debug_bounds("drag-drop-overlay"),
+        None,
+        "no veil at rest"
+    );
+    cx.simulate_event(FileDropEvent::Entered {
+        position: point(px(8.0), px(8.0)),
+        paths: ExternalPaths::default(),
+    });
+    settle(cx);
+    assert!(
+        cx.debug_bounds("drag-drop-overlay").is_some(),
+        "files over the composer raise the veil"
+    );
+}