fix(ai): show chat step details

crates/op-editor-ui/src/widgets/ai_chat_transcript.rs

@@ -37,6 +37,10 @@ const MSG_GAP: f32 = 10.0;
 const SUB_GAP: f32 = 4.0;
 /// Height of one compact design-progress step row.
 const ACTION_STEP_H: f32 = 28.0;
+/// Height of one detail line under a progress step.
+const ACTION_DETAIL_LINE_H: f32 = 14.0;
+/// Gap between the progress title row and detail lines.
+const ACTION_DETAIL_GAP: f32 = 4.0;
 /// Vertical gap between compact design-progress rows.
 const ACTION_STEP_GAP: f32 = 4.0;
 /// Side length of an image thumbnail box.
@@ -75,6 +79,7 @@ pub(crate) struct Collapsible {
 pub(crate) struct ActionStep {
     pub rect: Rect,
     pub label: String,
+    pub details: Vec<String>,
     pub done: bool,
     pub active: bool,
     pub failed: bool,
@@ -209,14 +214,21 @@ fn build_item(
     let total_steps = progress_steps.len();
     for (i, step) in progress_steps.iter().enumerate() {
         let (done, active, failed) = step_state(step, msg.streaming, i, total_steps);
+        let details: Vec<String> = step
+            .details
+            .iter()
+            .flat_map(|line| wrap_units(line, budget.saturating_sub(4)))
+            .collect();
+        let step_h = action_step_height(details.len());
         steps.push(ActionStep {
-            rect: Rect::xywh(x, y, bubble_w, ACTION_STEP_H),
+            rect: Rect::xywh(x, y, bubble_w, step_h),
             label: step.title.clone(),
+            details,
             done,
             active,
             failed,
         });
-        y += ACTION_STEP_H + ACTION_STEP_GAP;
+        y += step_h + ACTION_STEP_GAP;
     }
 
     let thinking = build_collapsible(
@@ -303,6 +315,14 @@ fn build_item(
     )
 }
 
+fn action_step_height(detail_count: usize) -> f32 {
+    if detail_count == 0 {
+        ACTION_STEP_H
+    } else {
+        ACTION_STEP_H + ACTION_DETAIL_GAP + detail_count as f32 * ACTION_DETAIL_LINE_H
+    }
+}
+
 /// Lay out the tail of `messages` that fits inside `body_rect`,
 /// top-aligned. Each item carries absolute rects ready for paint and
 /// hit-test.
@@ -523,6 +543,23 @@ fn paint_action_step(cx: &mut PaintCx<'_>, theme: &Theme, step: &ActionStep) {
         11.0,
         label_color,
     );
+    if !step.details.is_empty() {
+        cx.backend.save();
+        cx.backend.clip_rect(step.rect);
+        let mut baseline = step.rect.origin.y + ACTION_STEP_H + ACTION_DETAIL_GAP + 9.0;
+        for line in &step.details {
+            draw_line(
+                cx,
+                line,
+                step.rect.origin.x + 32.0,
+                baseline,
+                10.0,
+                theme.muted_foreground,
+            );
+            baseline += ACTION_DETAIL_LINE_H;
+        }
+        cx.backend.restore();
+    }
 }
 
 /// Paint a collapsible block — header row (chevron + label) plus,

crates/op-editor-ui/src/widgets/ai_chat_transcript_steps.rs

@@ -10,6 +10,7 @@ pub(crate) enum ParsedStepStatus {
 pub(crate) struct ParsedStep {
     pub title: String,
     pub status: Option<ParsedStepStatus>,
+    pub details: Vec<String>,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -28,6 +29,7 @@ pub(crate) fn split_design_progress(thinking: &str) -> (Vec<ParsedStep>, String)
                 steps.push(ParsedStep {
                     title: label.to_string(),
                     status: None,
+                    details: Vec::new(),
                 });
             }
         } else if !trimmed.is_empty() {
@@ -81,7 +83,7 @@ fn finish_extraction(steps: Vec<ParsedStep>, visible: String) -> StepExtraction
     }
 }
 
-fn parsed_step(attrs: &str, _content: &str, partial: bool) -> ParsedStep {
+fn parsed_step(attrs: &str, content: &str, partial: bool) -> ParsedStep {
     let default_title = if partial { "Design" } else { "Processing" };
     ParsedStep {
         title: attr_value(attrs, "title")
@@ -89,9 +91,19 @@ fn parsed_step(attrs: &str, _content: &str, partial: bool) -> ParsedStep {
             .filter(|s| !s.is_empty())
             .unwrap_or_else(|| default_title.to_string()),
         status: attr_value(attrs, "status").and_then(|s| parse_status(s.trim())),
+        details: step_details(content),
     }
 }
 
+fn step_details(content: &str) -> Vec<String> {
+    content
+        .lines()
+        .map(str::trim)
+        .filter(|line| !line.is_empty())
+        .map(str::to_string)
+        .collect()
+}
+
 fn parse_status(value: &str) -> Option<ParsedStepStatus> {
     match value.to_ascii_lowercase().as_str() {
         "pending" => Some(ParsedStepStatus::Pending),
@@ -163,6 +175,7 @@ mod tests {
             vec![ParsedStep {
                 title: "Check".into(),
                 status: Some(ParsedStepStatus::Done),
+                details: vec!["ok".into()],
             }]
         );
     }

crates/op-editor-ui/src/widgets/ai_chat_transcript_tests.rs

@@ -154,6 +154,35 @@ fn step_tag_content_renders_as_progress_not_raw_bubble() {
     );
 }
 
+#[test]
+fn step_tag_content_surfaces_as_progress_details() {
+    let mut message = ChatMessage::assistant_streaming();
+    message.content = r#"<step title="Validate design" status="streaming">
+lint: fixed spacing
+render: captured frame
+</step>"#
+        .into();
+
+    let items = build_transcript(
+        std::slice::from_ref(&message),
+        body(),
+        op_editor_core::Locale::EnUs,
+    );
+
+    assert_eq!(items[0].steps.len(), 1);
+    assert_eq!(
+        items[0].steps[0].details,
+        vec![
+            "lint: fixed spacing".to_string(),
+            "render: captured frame".to_string()
+        ]
+    );
+    assert!(
+        items[0].steps[0].rect.size.y > 28.0,
+        "step details should reserve space instead of being dropped"
+    );
+}
+
 #[test]
 fn tool_calls_block_header_label_counts_the_calls() {
     let mut m = ChatMessage::assistant("done");