T24b round 1 fix

- AgentProgress splits its bar only for two steps or more; a task of one
  step draws a plain bar
- test a_task_of_one_step_draws_before_and_after renders 0 of 1 and 1 of 1

TASKS.md

@@ -275,3 +275,4 @@ Per-component lines live in `tasks/`. Tags there:
 | T24a | 1 | FAIL | tall arguments pushed the approval dialog's title and buttons off screen; a long tool name in a narrow column pushed the time and chevron out of the card; the dark capture closed the card the light one opened |
 | T24a | 2 | FAIL | a dialog body's children shrank to the capped column instead of scrolling: a 2000px body drew at 860px and a scroll moved nothing |
 | T24a | 3 | PASS | |
+| T24b | 1 | FAIL | a task of one step crashed at render: its bar asked for one segment, and a segmented bar needs two |

src/agent/progress.rs

@@ -246,7 +246,7 @@ impl RenderOnce for AgentStatus {
     }
 }
 
-/// How far an agent has come: the step at work, how many are done of how many, the time so far, and a bar split by step.
+/// How far an agent has come: the step at work, how many are done of how many, the time so far, and a bar split by step when there are two or more.
 #[derive(IntoElement)]
 pub struct AgentProgress {
     id: ElementId,
@@ -309,9 +309,13 @@ impl RenderOnce for AgentProgress {
                         tabular(div().flex_none().text_color(colors.fg_subtle)).child(took(spent))
                     })),
             )
-            .child(
-                ProgressBar::new((self.id, "bar"), self.done as f32 / self.total as f32)
-                    .segments(self.total),
-            )
+            .child({
+                let bar = ProgressBar::new((self.id, "bar"), self.done as f32 / self.total as f32);
+                if self.total >= 2 {
+                    bar.segments(self.total)
+                } else {
+                    bar
+                }
+            })
     }
 }

src/agent/tests.rs

@@ -129,3 +129,28 @@ fn the_prompt_walks_deny_always_then_once(cx: &mut TestAppContext) {
 fn progress_past_its_total_fails_loud() {
     let _ = AgentProgress::new("progress", "Writing", 6, 5);
 }
+
+/// A progress bar for a task of one step, `done` or not.
+struct Single {
+    done: usize,
+}
+
+impl Render for Single {
+    fn render(&mut self, _: &mut Window, _: &mut Context<Self>) -> impl IntoElement {
+        div()
+            .w_full()
+            .child(AgentProgress::new("single", "The one step", self.done, 1))
+    }
+}
+
+#[gpui::test]
+fn a_task_of_one_step_draws_before_and_after(cx: &mut TestAppContext) {
+    cx.update(Theme::init);
+    let (view, cx) = cx.add_window_view(|_, _| Single { done: 0 });
+    settle(cx);
+    view.update(cx, |single, cx| {
+        single.done = 1;
+        cx.notify();
+    });
+    settle(cx);
+}