tui: breathing spinner on true-color terms (#4853)

uses the same logic as shimmer_spans to render the `•` spinner. on
terminals without true-color support, fall back to the existing `•/◦`
blinking logic.



https://github.com/user-attachments/assets/19db76f2-8fa2-440d-9fde-7bed67f4c4dc

Author: nornagon-openai

codex-rs/tui/src/exec_cell/render.rs

@@ -8,6 +8,7 @@ use crate::history_cell::HistoryCell;
 use crate::render::highlight::highlight_bash_to_lines;
 use crate::render::line_utils::prefix_lines;
 use crate::render::line_utils::push_owned_lines;
+use crate::shimmer::shimmer_spans;
 use crate::wrapping::RtOptions;
 use crate::wrapping::word_wrap_line;
 use codex_ansi_escape::ansi_escape_line;
@@ -116,10 +117,16 @@ pub(crate) fn output_lines(
 }
 
 pub(crate) fn spinner(start_time: Option<Instant>) -> Span<'static> {
-    let blink_on = start_time
-        .map(|st| ((st.elapsed().as_millis() / 600) % 2) == 0)
-        .unwrap_or(false);
-    if blink_on { "•".into() } else { "◦".dim() }
+    let elapsed = start_time.map(|st| st.elapsed()).unwrap_or_default();
+    if supports_color::on_cached(supports_color::Stream::Stdout)
+        .map(|level| level.has_16m)
+        .unwrap_or(false)
+    {
+        shimmer_spans("•")[0].clone()
+    } else {
+        let blink_on = (elapsed.as_millis() / 600).is_multiple_of(2);
+        if blink_on { "•".into() } else { "◦".dim() }
+    }
 }
 
 impl HistoryCell for ExecCell {

codex-rs/tui/src/status_indicator_widget.rs

@@ -15,6 +15,7 @@ use ratatui::widgets::WidgetRef;
 
 use crate::app_event::AppEvent;
 use crate::app_event_sender::AppEventSender;
+use crate::exec_cell::spinner;
 use crate::key_hint;
 use crate::shimmer::shimmer_spans;
 use crate::tui::FrameRequester;
@@ -163,15 +164,11 @@ impl WidgetRef for StatusIndicatorWidget {
         let now = Instant::now();
         let elapsed_duration = self.elapsed_duration_at(now);
         let pretty_elapsed = fmt_elapsed_compact(elapsed_duration.as_secs());
-        let blink_on = (elapsed_duration.as_millis() / 600).is_multiple_of(2);
 
         // Plain rendering: no borders or padding so the live cell is visually indistinguishable from terminal scrollback.
         let mut spans = Vec::with_capacity(5);
-        if blink_on {
-            spans.push("• ".into());
-        } else {
-            spans.push("◦ ".dim());
-        }
+        spans.push(spinner(Some(self.last_resume_at)));
+        spans.push(" ".into());
         spans.extend(shimmer_spans(&self.header));
         spans.extend(vec![
             " ".into(),