T23c: AI chat, input

- PromptInput: attachments and context above the field, the owner's tools and
  send below; Enter sends, Shift-Enter breaks the line; / offers commands and
  @ offers context over forms::Suggestions; files dropped on it attach behind a
  drop veil
- AttachmentButton, AttachmentChip with thumbnails and uploads, ContextChips
- VoiceInputButton and VoiceWaveform with a red dot and the time
- ParameterPanel, SystemPromptEditor, TokenCounter, CostEstimator
- forms: a Newline action on Shift-Enter keeps one-line fields to one line;
  replace_trigger moves beside Suggestions; choose and dropped shared
- gallery: composer, pickers and tuning

src/chat/tests/compose.rs

@@ -0,0 +1,118 @@
+use gpui::{
+    AppContext as _, Context, Entity, Focusable, IntoElement, ParentElement, Render, SharedString,
+    Styled, TestAppContext, VisualTestContext, Window, div,
+};
+
+use super::settle;
+use crate::{
+    chat::PromptInput,
+    forms::{self, Choice, TextInput},
+    theme::Theme,
+};
+
+/// A composer over a field, and what it asked: sends, commands and context.
+struct Compose {
+    field: Entity<TextInput>,
+    busy: bool,
+    sent: usize,
+    picked: Vec<SharedString>,
+}
+
+impl Render for Compose {
+    fn render(&mut self, _: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
+        let (send, command, mention) = (cx.entity(), cx.entity(), cx.entity());
+        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())),
+        )
+        .context([Choice::new("lift", "lift.rs")], move |value, _, cx| {
+            mention.update(cx, |compose, _| compose.picked.push(value.clone()))
+        });
+        let input = if self.busy {
+            input.busy(|_, _| {})
+        } else {
+            input
+        };
+        div().size_full().child(input)
+    }
+}
+
+fn open(busy: bool, cx: &mut TestAppContext) -> (Entity<Compose>, &mut VisualTestContext) {
+    cx.update(|cx| {
+        Theme::init(cx);
+        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,
+        sent: 0,
+        picked: Vec::new(),
+    });
+    cx.update(|window, cx| {
+        window.activate_window();
+        let field = compose.read(cx).field.focus_handle(cx);
+        window.focus(&field);
+    });
+    settle(cx);
+    (compose, cx)
+}
+
+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);
+    cx.simulate_keystrokes("enter");
+    assert_eq!(
+        compose.read_with(cx, |compose, _| compose.sent),
+        0,
+        "nothing to send"
+    );
+    cx.simulate_input("lift");
+    cx.simulate_keystrokes("shift-enter");
+    settle(cx);
+    assert_eq!(text(&compose, cx), "lift\n");
+    cx.simulate_input("tone");
+    settle(cx);
+    cx.simulate_keystrokes("enter");
+    assert_eq!(compose.read_with(cx, |compose, _| compose.sent), 1);
+    assert_eq!(
+        text(&compose, cx),
+        "lift\ntone",
+        "Enter sends without a new line"
+    );
+}
+
+#[gpui::test]
+fn a_slash_picks_a_command_and_an_at_sign_picks_context(cx: &mut TestAppContext) {
+    let (compose, cx) = open(false, cx);
+    cx.simulate_input("/sum");
+    settle(cx);
+    cx.simulate_keystrokes("enter");
+    settle(cx);
+    assert_eq!(text(&compose, cx), "", "the command's words go");
+    cx.simulate_input("see @li");
+    settle(cx);
+    cx.simulate_keystrokes("enter");
+    settle(cx);
+    assert_eq!(text(&compose, cx), "see ");
+    compose.read_with(cx, |compose, _| {
+        assert_eq!(compose.picked, ["summarize", "lift"]);
+        assert_eq!(compose.sent, 0, "a pick is not a send");
+    });
+}
+
+#[gpui::test]
+fn a_busy_composer_holds_its_message(cx: &mut TestAppContext) {
+    let (compose, cx) = open(true, 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");
+}

src/chat/tests/mod.rs

@@ -8,6 +8,7 @@ use gpui::{
 };
 
 mod cite;
+mod compose;
 
 use super::{
     ImageMessage, MessageAvatar, MessageBubble, MessageEditor, MessageList, Role, ThinkingBlock,