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fix(timeline): four correctness bugs in the message body #281

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Merged
tyreseluo merged 3 commits into from
Jul 31, 2026
Merged

fix(timeline): four correctness bugs in the message body #281

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caab4e7
fix(link-preview): truncate the description by characters, not bytes
tyreseluo Jul 31, 2026
9e94340
fix(timeline): stop folding mid-stream, and clear the bot card betwee…
tyreseluo Jul 31, 2026
58cab28
fix: typo in a test comment (paniced -> panicked)
tyreseluo Jul 31, 2026
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53 changes: 51 additions & 2 deletions src/home/link_preview.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -419,8 +419,16 @@ impl LinkPreviewRef {
if let Some(description) = &link_preview_data.description {
let mut description = description.clone();
description = description.replace("\n\n", " ");
let truncated_description = if description.len() > MAX_DESCRIPTION_LENGTH {
format!("{}...", &description[..(MAX_DESCRIPTION_LENGTH - 3)])
// Truncate by characters, not bytes. `MAX_DESCRIPTION_LENGTH` counted
// bytes and the slice cut at a fixed byte offset, which panics
// whenever that offset lands inside a multi-byte character — routine
// for any description mixing CJK with ASCII.
let truncated_description = if description.chars().count() > MAX_DESCRIPTION_LENGTH {
let head: String = description
.chars()
.take(MAX_DESCRIPTION_LENGTH - 3)
.collect();
format!("{head}...")
} else {
description
};
Expand Down Expand Up @@ -804,3 +812,44 @@ fn insert_into_cache(
}
SignalToUI::set_ui_signal();
}

#[cfg(test)]
mod truncation_tests {
use super::MAX_DESCRIPTION_LENGTH;

/// Mirrors the truncation in `populate_view`. The previous byte-slice form
/// panicked whenever byte `MAX_DESCRIPTION_LENGTH - 3` landed inside a
/// multi-byte character.
fn truncate(description: String) -> String {
if description.chars().count() > MAX_DESCRIPTION_LENGTH {
let head: String = description.chars().take(MAX_DESCRIPTION_LENGTH - 3).collect();
format!("{head}...")
} else {
description
}
}

#[test]
fn mixed_script_description_does_not_panic() {
// The byte offset lands mid-character for this mix — the old code panicked.
let d = "Robrix 是一个 Matrix 客户端,支持多 agent 协作工作流。".repeat(6);
assert!(!d.is_char_boundary(MAX_DESCRIPTION_LENGTH - 3));
let out = truncate(d);
assert!(out.ends_with("..."));
assert_eq!(out.chars().count(), MAX_DESCRIPTION_LENGTH);
}

#[test]
fn cjk_and_emoji_truncate_by_characters() {
for d in ["中文描述内容测试".repeat(40), "📋 项目说明 mixed ".repeat(30)] {
let out = truncate(d);
assert_eq!(out.chars().count(), MAX_DESCRIPTION_LENGTH);
}
}

#[test]
fn short_description_is_untouched() {
let d = "短描述".to_string();
assert_eq!(truncate(d.clone()), d);
}
}
60 changes: 57 additions & 3 deletions src/home/room_screen.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2856,7 +2856,14 @@ script_mod! {
padding: Inset{ left: 0.0, right: 6.0, top: 0.0, bottom: 0.0 }
draw_text +: {
text_style: mod.widgets.MESSAGE_TEXT_STYLE { font_size: 9.5 }
// The base widget only defines color/hover/down,
// so an unset focus colour turned the label white
// the moment a click focused it, until a later
// redraw happened to reset the state.
color: (mod.widgets.RBX_ACCENT)
color_hover: (mod.widgets.RBX_ACCENT_HOVER)
color_down: (mod.widgets.RBX_ACCENT_PRESSED)
color_focus: (mod.widgets.RBX_ACCENT)
}
text: ""
}
Expand All @@ -2872,7 +2879,14 @@ script_mod! {
spacing: 0
draw_text +: {
text_style: mod.widgets.MESSAGE_TEXT_STYLE { font_size: 9.5 }
// The base widget only defines color/hover/down,
// so an unset focus colour turned the label white
// the moment a click focused it, until a later
// redraw happened to reset the state.
color: (mod.widgets.RBX_ACCENT)
color_hover: (mod.widgets.RBX_ACCENT_HOVER)
color_down: (mod.widgets.RBX_ACCENT_PRESSED)
color_focus: (mod.widgets.RBX_ACCENT)
}
text: ""
}
Expand Down Expand Up @@ -3022,7 +3036,14 @@ script_mod! {
padding: Inset{ left: 0.0, right: 6.0, top: 0.0, bottom: 0.0 }
draw_text +: {
text_style: mod.widgets.MESSAGE_TEXT_STYLE { font_size: 9.5 }
// The base widget only defines color/hover/down,
// so an unset focus colour turned the label white
// the moment a click focused it, until a later
// redraw happened to reset the state.
color: (mod.widgets.RBX_ACCENT)
color_hover: (mod.widgets.RBX_ACCENT_HOVER)
color_down: (mod.widgets.RBX_ACCENT_PRESSED)
color_focus: (mod.widgets.RBX_ACCENT)
}
text: ""
}
Expand All @@ -3038,7 +3059,14 @@ script_mod! {
spacing: 0
draw_text +: {
text_style: mod.widgets.MESSAGE_TEXT_STYLE { font_size: 9.5 }
// The base widget only defines color/hover/down,
// so an unset focus colour turned the label white
// the moment a click focused it, until a later
// redraw happened to reset the state.
color: (mod.widgets.RBX_ACCENT)
color_hover: (mod.widgets.RBX_ACCENT_HOVER)
color_down: (mod.widgets.RBX_ACCENT_PRESSED)
color_focus: (mod.widgets.RBX_ACCENT)
}
text: ""
}
Expand Down Expand Up @@ -12564,6 +12592,7 @@ fn populate_message_view(
Some(link_preview_cache),
sender_is_bot(),
bot_body_expanded,
true, // streaming
);
band_metadata = stream_meta;
new_drawn_status.content_drawn = false; // force re-render
Expand Down Expand Up @@ -12604,6 +12633,7 @@ fn populate_message_view(
Some(link_preview_cache),
sender_is_bot(),
bot_body_expanded,
false,
);
new_drawn_status.content_drawn = bot_drawn;
band_metadata = bot_meta;
Expand Down Expand Up @@ -12660,6 +12690,7 @@ fn populate_message_view(
Some(link_preview_cache),
sender_is_bot(),
bot_body_expanded,
false,
);
new_drawn_status.content_drawn = bot_drawn;
band_metadata = bot_meta;
Expand All @@ -12673,6 +12704,7 @@ fn populate_message_view(
if existed && item_drawn_status.content_drawn {
(item, true)
} else {
reset_bot_message_card(cx, &item);
let html_or_plaintext_ref = item.html_or_plaintext(cx, ids!(content.message));
// Apply red color to all text styles for server notices.
let mut html_widget = html_or_plaintext_ref.html(cx, ids!(html_view.html));
Expand Down Expand Up @@ -13050,6 +13082,7 @@ fn populate_message_view(
if existed && item_drawn_status.content_drawn {
(item, true)
} else {
reset_bot_message_card(cx, &item);
item.label(cx, ids!(content.message)).set_text(
cx,
&format!("{} {:?} ", tr_key(app_language, "room_screen.unsupported.prefix"), other),
Expand Down Expand Up @@ -13422,6 +13455,19 @@ fn populate_bot_badge_identity(cx: &mut Cx, item: &WidgetRef, sender_localpart:
}
}

/// Puts a `Message` item back into its plain (non-bot-card) state.
///
/// `populate_bot_text_message_content` is the only code that flips these two
/// visibilities, and it only runs on the text/notice path. The PortalList hands
/// the *same* `Message` widget to the server-notice and unsupported/redacted
/// paths as well, so a slot that previously held a bot reply would keep drawing
/// that reply's card while the new content sat hidden underneath it. Every
/// branch that renders into `content.message` must call this first.
fn reset_bot_message_card(cx: &mut Cx, item: &WidgetRef) {
item.view(cx, ids!(content.bot_message_card)).set_visible(cx, false);
item.html_or_plaintext(cx, ids!(content.message)).set_visible(cx, true);
}

fn populate_bot_text_message_content(
cx: &mut Cx,
item: &WidgetRef,
Expand All @@ -13434,6 +13480,8 @@ fn populate_bot_text_message_content(
link_preview_cache: Option<&mut LinkPreviewCache>,
is_bot_sender: bool,
bot_body_expanded: bool,
// True while the body is still being streamed in; suppresses folding.
is_streaming: bool,
) -> (bool, Option<String>) {
let render_state = compute_bot_timeline_render_state(body, is_bot_sender);
let bot_card_view = item.view(cx, ids!(content.bot_message_card));
Expand Down Expand Up @@ -13501,13 +13549,19 @@ fn populate_bot_text_message_content(
// Fold state: a long body renders its preview until the user expands it.
// `folded_body` is `None` for short bodies, so the toggle stays hidden and
// the full text renders exactly as before.
let is_folded = render_state.folded_body.is_some() && !bot_body_expanded;
//
// A streaming reply is never folded. Its body grows on every frame, so the
// moment it crosses the threshold the text the user is watching appear would
// collapse to three lines and take the typewriter cursor with it — the reply
// reads as having stalled. Folding applies once the message has settled.
let foldable = render_state.folded_body.is_some() && !is_streaming;
let is_folded = foldable && !bot_body_expanded;
let fold_toggle = item.button(
cx,
ids!(content.bot_message_card.bot_body_card.bot_card_footer_row.bot_body_fold_toggle),
);
fold_toggle.set_visible(cx, render_state.folded_body.is_some());
if render_state.folded_body.is_some() {
fold_toggle.set_visible(cx, foldable);
if foldable {
fold_toggle.set_text(cx, if is_folded { "Show more" } else { "Show less" });
}

Expand Down
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