Mail · a folded message keeps focus as it opens, and gives way at 280px

Each message in a thread holds one focus handle, a Tab stop while
folded and tracked on the letter once open, so a keyboard open keeps
focus on the message and Tab goes on to its Reply. A press on a fold
leaves focus alone. A fold's name now gives way with its words, so a
long name beside a long date stays inside the row.

AGENTS.md

@@ -74,7 +74,7 @@ Ely GPUI Component. A component library for GPUI, in light and dark.
 - gpui runs the click of every pressed element under the pointer, a row's with its button's. A pressable row that holds buttons stops their press at their box on mouse down (`files::transfer`), as `overlays::media_button` stops its own.
 - gpui draws a window's first frame inside `open_window`. State the first frame reads, such as `cx.set_menus`, is set before it opens.
 - gpui clicks a focused element when Enter or Space is released. An overlay that hands focus back picks on release too; a pick on press returns focus first, and the release clicks the opener again. An edit in place that hands focus back keeps its text on Enter's release (`forms::InlineEdit`). The press itself bubbles, so a container that takes Space leaves a focused button its own: `overlays::media_button` stops it, and a button in a `SelectableList` row stops Space and Enter at its box (`mail::MailItem`'s star, `messaging::PinnedMessages`' Unpin).
-- A focus handle a component hands back lives across all its modes: take it with `tab_stop` before any early return, or keyed state drops it while the other mode draws and the handed-back focus lands nowhere.
+- A focus handle a component hands back lives across all its modes: take it with `tab_stop` before any early return, or keyed state drops it while the other mode draws and the handed-back focus lands nowhere. A thread's message keeps one handle folded and open, a Tab stop only while folded (`mail::MailThreadView`).
 - A dialog goes through `overlays::Dialog`: scrim, focus trap, Escape and focus return live there. Its close runs on every way out, so a dialog with two answers marks the chosen one before it closes (`messaging::IncomingCallDialog`). AlertDialog, ConfirmDialog and PromptDialog build on it; a fullscreen dialog fills the window below its title bar. A dialog's card fits the window, a title bar's height clear at each end; its body scrolls and its actions stay.
 - Controls on a dark layer over pictures are `overlays::media_button`, light icons that dim when they have nowhere to go, for the lightbox and a video player's bar alike.
 - A component's letter keys step aside while Command or Control is held, so the app's shortcuts reach the app (`media::ImageAnnotator`, `VideoPlayer`, `VideoThumbnailStrip`).

src/mail/tests/read.rs

@@ -1,8 +1,11 @@
-use gpui::{Entity, IntoElement, ParentElement, TestAppContext, div};
-use jiff::{Timestamp, tz::TimeZone};
+use gpui::{Entity, IntoElement, Modifiers, ParentElement, Styled, TestAppContext, div, px};
+use jiff::{SignedDuration, Timestamp, tz::TimeZone};
 
-use super::{Mailing, heard, mailing, note, press, tab_to};
-use crate::mail::{Contact, MailReader, MailThreadView, Message, QuotedText};
+use super::{Mailing, heard, mailing, note, press, settle, tab_to};
+use crate::{
+    buttons::Button,
+    mail::{Contact, MailReader, MailThreadView, Message, QuotedText},
+};
 
 fn ana() -> Contact {
     Contact::new("Ana Lima", "ana@atrium.studio")
@@ -116,3 +119,83 @@ fn quoted_words_stay_folded_until_asked(cx: &mut TestAppContext) {
     press("space", cx);
     assert!(cx.debug_bounds("quoted quote").is_some());
 }
+
+/// A button, then a thread of three whose Reply the host hears.
+fn answered(owner: Entity<Mailing>) -> gpui::AnyElement {
+    let (before, reply) = (owner.clone(), owner);
+    let message = |key: &'static str| {
+        Message::new(key, ana(), Timestamp::UNIX_EPOCH)
+            .to([ben()])
+            .snippet("Earlier words")
+    };
+    div()
+        .child(
+            Button::new("before", "Before")
+                .on_click(move |_, _, cx| note(&before, "before".into(), cx)),
+        )
+        .child(
+            MailThreadView::new("thread", "Friday's review")
+                .zone(TimeZone::UTC)
+                .on_reply(move |key, _, cx| note(&reply, format!("reply {key}"), cx))
+                .message(message("m1"), div().child("First"))
+                .message(message("m2"), div().child("Second"))
+                .message(message("m3"), div().child("Newest")),
+        )
+        .into_any_element()
+}
+
+#[gpui::test]
+fn a_press_on_a_fold_leaves_focus_alone(cx: &mut TestAppContext) {
+    let (host, cx) = mailing(answered, cx);
+    tab_to(1, cx);
+    let fold = cx.debug_bounds("fold m1").expect("the first fold draws");
+    cx.simulate_click(fold.center(), Modifiers::none());
+    settle(cx);
+    press("space", cx);
+    assert_eq!(heard(&host, cx), ["before"], "the button kept focus");
+}
+
+#[gpui::test]
+fn space_on_a_fold_keeps_focus_on_the_message(cx: &mut TestAppContext) {
+    let (host, cx) = mailing(answered, cx);
+    tab_to(2, cx);
+    press("space", cx);
+    cx.update(|window, _| window.focus_next());
+    settle(cx);
+    press("space", cx);
+    assert_eq!(
+        heard(&host, cx),
+        ["reply m1"],
+        "Tab went on to the opened message's Reply"
+    );
+}
+
+#[gpui::test]
+fn a_fold_keeps_its_parts_inside_at_280(cx: &mut TestAppContext) {
+    let (_, cx) = mailing(
+        |_| {
+            let long = Contact::new(
+                "Anastasia Lima-Fernández de la Torre",
+                "anastasia@atrium.studio",
+            );
+            let old = Timestamp::now() - SignedDuration::from_hours(24 * 20);
+            div()
+                .w(px(280.0))
+                .child(
+                    MailThreadView::new("thread", "Samples")
+                        .zone(TimeZone::UTC)
+                        .message(
+                            Message::new("m1", long, old)
+                                .snippet("The lime reads warmest by the windows."),
+                            div().child("Earlier"),
+                        )
+                        .message(Message::new("m2", ana(), old), div().child("Newest")),
+                )
+                .into_any_element()
+        },
+        cx,
+    );
+    let fold = cx.debug_bounds("fold m1").expect("the fold draws");
+    let date = cx.debug_bounds("fold-date m1").expect("its date draws");
+    assert!(date.right() <= fold.right(), "{date:?} inside {fold:?}");
+}

src/mail/thread.rs

@@ -1,8 +1,9 @@
 use std::rc::Rc;
 
 use gpui::{
-    AnyElement, App, ElementId, FontWeight, InteractiveElement, IntoElement, ParentElement,
-    RenderOnce, SharedString, StatefulInteractiveElement, Styled, Window, div, prelude::*,
+    AnyElement, App, ElementId, FocusHandle, FontWeight, InteractiveElement, IntoElement,
+    MouseButton, ParentElement, RenderOnce, SharedString, StatefulInteractiveElement, Styled,
+    Window, div, prelude::*,
 };
 use jiff::{Timestamp, tz::TimeZone};
 use smallvec::SmallVec;
@@ -10,7 +11,7 @@ use smallvec::SmallVec;
 use super::reader::{Asks, Message, open_letter};
 use crate::{
     data_display::Avatar,
-    primitives::FocusRing,
+    primitives::{FocusRing, tab_stop},
     theme::{ActiveTheme, AvatarSize, Radius, TextSize},
     typography::{Ellipsis, format},
 };
@@ -103,21 +104,34 @@ impl RenderOnce for MailThreadView {
         let now = Timestamp::now();
         let newest = self.messages.len() - 1;
         let open_now = opened.read(cx).clone();
+        let focuses: Vec<FocusHandle> = self
+            .messages
+            .iter()
+            .enumerate()
+            .map(|(ix, (message, _))| {
+                let folded = ix != newest && !open_now.contains(&message.key);
+                let id = (self.id.clone(), format!("message-{}", message.key)).into();
+                tab_stop(id, folded, window, cx)
+            })
+            .collect();
         let theme = cx.theme();
         let colors = &theme.colors;
-        let messages = self
-            .messages
-            .into_iter()
-            .enumerate()
-            .map(|(ix, (message, body))| {
+        let messages = self.messages.into_iter().zip(focuses).enumerate().map(
+            |(ix, ((message, body), focus))| {
                 let open = ix == newest || open_now.contains(&message.key);
                 let part = if open {
-                    open_letter(&self.id, &message, body, &zone, &self.asks, cx).into_any_element()
+                    open_letter(&self.id, &message, body, &zone, &self.asks, cx)
+                        .track_focus(&focus)
+                        .into_any_element()
                 } else {
                     let (key, opening, id) = (message.key.clone(), opened.clone(), self.id.clone());
                     let date = format::relative(message.at, now);
                     div()
                         .id((self.id.clone(), format!("fold-{}", message.key)))
+                        .debug_selector({
+                            let key = message.key.clone();
+                            move || format!("fold {key}")
+                        })
                         .flex()
                         .items_center()
                         .gap_3()
@@ -126,11 +140,12 @@ impl RenderOnce for MailThreadView {
                         .rounded(theme.radius(Radius::Md))
                         .border_1()
                         .border_color(gpui::transparent_black())
-                        .tab_index(0)
+                        .track_focus(&focus)
                         .focus_ring(cx)
                         .cursor_pointer()
                         .hover(|style| style.bg(colors.hover))
                         .text_size(theme.text_size(TextSize::Sm))
+                        .on_mouse_down(MouseButton::Left, |_, window, _| window.prevent_default())
                         .on_click(move |_, _, cx| {
                             log::info!("mail thread {id}: open {key}");
                             opening.update(cx, |opened, cx| {
@@ -149,7 +164,7 @@ impl RenderOnce for MailThreadView {
                         )
                         .child(
                             div()
-                                .flex_none()
+                                .min_w_0()
                                 .max_w(theme.label_width())
                                 .font_weight(FontWeight::SEMIBOLD)
                                 .text_color(colors.fg)
@@ -164,6 +179,10 @@ impl RenderOnce for MailThreadView {
                         )
                         .child(
                             div()
+                                .debug_selector({
+                                    let key = message.key.clone();
+                                    move || format!("fold-date {key}")
+                                })
                                 .flex_none()
                                 .text_size(theme.text_size(TextSize::Xs))
                                 .text_color(colors.fg_subtle)
@@ -176,7 +195,8 @@ impl RenderOnce for MailThreadView {
                         row.pt_3().border_t_1().border_color(colors.border)
                     })
                     .child(part)
-            });
+            },
+        );
         div()
             .debug_selector(|| "mail-thread".into())
             .w_full()