Refactor TUI scrolling logic: replace manual scroll calculations with AutoScroll abstraction, enhance line wrapping, and improve viewport handling.

crates/owlen-tui/src/ui.rs

@@ -357,6 +357,7 @@ fn render_messages(frame: &mut Frame<'_>, area: Rect, app: &mut ChatApp) {
     // Reserve space for borders and the message indent so text fits within the block
     formatter.set_wrap_width(usize::from(content_width));
 
+    // Build the lines for messages
     let mut lines: Vec<Line> = Vec::new();
     for (message_index, message) in conversation.messages.iter().enumerate() {
         let role = &message.role;
@@ -434,16 +435,34 @@ fn render_messages(frame: &mut Frame<'_>, area: Rect, app: &mut ChatApp) {
         lines.push(Line::from("No messages yet. Press 'i' to start typing."));
     }
 
-    let mut paragraph = Paragraph::new(lines)
+    // Wrap lines to get accurate content height
+    let wrapped: Vec<Line> = {
+        use textwrap::wrap;
+        let mut out = Vec::new();
+        for l in &lines {
+            let s = l.to_string();
+            for w in wrap(&s, content_width as usize) {
+                out.push(Line::from(w.into_owned()));
+            }
+        }
+        out
+    };
+
+    // Update AutoScroll state with accurate content length
+    let auto_scroll = app.auto_scroll_mut();
+    auto_scroll.content_len = wrapped.len();
+    auto_scroll.on_viewport(viewport_height);
+
+    let scroll_position = app.scroll().min(u16::MAX as usize) as u16;
+
+    let paragraph = Paragraph::new(wrapped)
         .block(
             Block::default()
                 .borders(Borders::ALL)
                 .border_style(Style::default().fg(Color::Rgb(95, 20, 135))),
         )
-        .wrap(Wrap { trim: false });
-
-    let scroll = app.scroll().min(u16::MAX as usize) as u16;
-    paragraph = paragraph.scroll((scroll, 0));
+        .wrap(Wrap { trim: false })
+        .scroll((scroll_position, 0));
 
     frame.render_widget(paragraph, area);
 }