Publish harness and TUI open-source

initial sync from the monorepo

crates/codegen/xai-ratatui-inline/src/scrollback.rs

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+use std::io::{self, Write};
+
+use crossterm::{cursor::MoveTo, style::Print};
+use ratatui::layout::Rect;
+
+use crate::{common::TerminalLike, segment::split_into_line_segments};
+
+// ANSI escape sequence constants.
+// CSI J with the default parameter (0): erase from cursor to end of display.
+// Byte-identical to what the previous termwiz constant
+// (`CSI::Edit(Edit::EraseInDisplay(EraseInDisplay::EraseToEndOfDisplay))`)
+// rendered, and to crossterm's `Clear(ClearType::FromCursorDown)`.
+const ANSI_CLEAR_FROM_CURSOR_DOWN: &str = "\x1b[J";
+
+pub fn emit_to_scrollback<T: TerminalLike>(terminal: &mut T, content: &str) -> io::Result<()> {
+    macro_rules! queue {
+        ($($command:expr),* $(,)?) => {{
+            $(crossterm::queue!(terminal.writer_mut(), $command)?;)*
+            Ok::<(), io::Error>(())
+        }};
+    }
+
+    let size = terminal.size()?;
+    let viewport_area = terminal.viewport_area();
+    let terminal_width = size.width as usize;
+    debug_assert!(viewport_area.bottom() <= size.height);
+
+    // Use zero-copy line segmentation
+    let segments = split_into_line_segments(content, terminal_width);
+
+    // Calculate where viewport will end up after content
+    let new_viewport_y =
+        (viewport_area.y + segments.len() as u16).min(size.height - viewport_area.height);
+
+    // Position from viewport top and clear from this position down
+    queue!(
+        MoveTo(0, viewport_area.y),
+        Print(ANSI_CLEAR_FROM_CURSOR_DOWN),
+    )?;
+
+    // Now print the content
+    queue!(MoveTo(0, viewport_area.y))?;
+    for segment in &segments {
+        queue!(Print(segment))?; // this already includes crlfs if there's any
+    }
+
+    // Create exact viewport space
+    for _ in 0..viewport_area.height {
+        queue!(Print("\r\n"))?;
+    }
+
+    // Clear the new viewport area for rendering
+    queue!(
+        MoveTo(0, new_viewport_y),
+        Print(ANSI_CLEAR_FROM_CURSOR_DOWN),
+    )?;
+
+    // We'll flush by default; the caller is expected to have this in sync block anyway
+    terminal.writer_mut().flush()?;
+
+    // Reset the back buffer so next render knows viewport is empty
+    terminal.reset_back_buffer();
+
+    // Reposition viewport if needed
+    if new_viewport_y != viewport_area.y {
+        terminal.set_viewport_area(Rect {
+            y: new_viewport_y,
+            ..viewport_area
+        });
+    }
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+
+    use crate::tests::MockTerminal;
+
+    use super::*;
+
+    // Helper to parse ANSI sequences from the captured buffer
+    fn parse_ansi_sequences(buffer: &[u8]) -> Vec<String> {
+        let text = String::from_utf8_lossy(buffer);
+        let mut sequences = Vec::new();
+        let mut current = String::new();
+        let mut in_escape = false;
+
+        for ch in text.chars() {
+            if ch == '\x1b' {
+                if !current.is_empty() {
+                    sequences.push(current.clone());
+                    current.clear();
+                }
+                in_escape = true;
+                current.push(ch);
+            } else if in_escape {
+                current.push(ch);
+                // Simple heuristic: most ANSI sequences end with a letter
+                if ch.is_alphabetic() {
+                    sequences.push(current.clone());
+                    current.clear();
+                    in_escape = false;
+                }
+            } else {
+                current.push(ch);
+            }
+        }
+
+        if !current.is_empty() {
+            sequences.push(current);
+        }
+
+        sequences
+    }
+
+    #[test]
+    fn test_simple_content() {
+        let mut terminal = MockTerminal::new(80, 25, 3);
+        let content = "Hello, World!";
+
+        emit_to_scrollback(&mut terminal, content).unwrap();
+
+        // Should have cleared once
+        assert_eq!(terminal.clear_count, 1);
+
+        // Check that content was written
+        let buffer = &terminal.writer.buffer;
+        assert!(!buffer.is_empty());
+
+        // Should have flushed
+        assert_eq!(terminal.writer.flush_count, 1);
+    }
+
+    #[test]
+    fn test_tall_content() {
+        let mut terminal = MockTerminal::new(80, 25, 3);
+        // Create content that will span more lines than viewport height
+        let content = "Line 1\nLine 2\nLine 3\nLine 4\nLine 5";
+
+        emit_to_scrollback(&mut terminal, content).unwrap();
+
+        // Should have cleared once
+        assert_eq!(terminal.clear_count, 1);
+
+        // Check that content was written
+        let buffer = &terminal.writer.buffer;
+        assert!(!buffer.is_empty());
+
+        // Should contain the content
+        let text = String::from_utf8_lossy(buffer);
+        assert!(text.contains("Line 1"));
+        assert!(text.contains("Line 5"));
+
+        // Should have flushed
+        assert_eq!(terminal.writer.flush_count, 1);
+    }
+
+    #[test]
+    fn test_content_with_viewport_at_bottom() {
+        let mut terminal = MockTerminal::new(80, 25, 3);
+        let content = "Hello, Multiplexer!";
+
+        emit_to_scrollback(&mut terminal, content).unwrap();
+
+        // Should have cleared once
+        assert_eq!(terminal.clear_count, 1);
+
+        // Check that content was written
+        let buffer = &terminal.writer.buffer;
+        assert!(!buffer.is_empty());
+
+        // Should have flushed
+        assert_eq!(terminal.writer.flush_count, 1);
+
+        // Viewport should remain at bottom
+        assert_eq!(terminal.viewport_area.y, 22); // 25 - 3
+    }
+
+    #[test]
+    fn test_viewport_not_at_bottom() {
+        let mut terminal = MockTerminal::new(80, 25, 3);
+        // Move viewport away from bottom
+        terminal.viewport_area.y = 10;
+
+        let content = "Test content";
+
+        emit_to_scrollback(&mut terminal, content).unwrap();
+
+        // Should have cleared
+        assert_eq!(terminal.clear_count, 1);
+
+        // Viewport should have moved down
+        assert_eq!(terminal.viewport_updates.len(), 1);
+        assert!(terminal.viewport_updates[0].y > 10);
+    }
+
+    #[test]
+    fn test_long_lines_wrapping() {
+        let mut terminal = MockTerminal::new(20, 10, 2);
+        // Content longer than terminal width
+        let content = "This is a very long line that should wrap at terminal boundaries";
+
+        emit_to_scrollback(&mut terminal, content).unwrap();
+
+        // Should have cleared once
+        assert_eq!(terminal.clear_count, 1);
+
+        // Should have written content
+        let buffer = &terminal.writer.buffer;
+        assert!(!buffer.is_empty());
+
+        // Should have flushed
+        assert_eq!(terminal.writer.flush_count, 1);
+    }
+
+    #[test]
+    fn test_ansi_color_preservation() {
+        let mut terminal = MockTerminal::new(80, 25, 3);
+        let content = "\x1b[31mRed Text\x1b[0m";
+
+        emit_to_scrollback(&mut terminal, content).unwrap();
+
+        // Check that ANSI codes are preserved in output
+        let buffer = &terminal.writer.buffer;
+        let text = String::from_utf8_lossy(buffer);
+        assert!(text.contains("Red Text"), "Text should be in output");
+
+        // The ANSI codes might be in the segment's content
+        let sequences = parse_ansi_sequences(buffer);
+        let has_color = sequences.iter().any(|s| s.contains("Red Text"));
+        assert!(has_color, "Colored text should be present");
+    }
+}