Streaming markdown (#1920)

We wait until we have an entire newline, then format it with markdown and stream in to the UI. This reduces time to first token but is the right thing to do with our current rendering model IMO. Also lets us add word wrapping!

codex-rs/tui/src/history_cell.rs

@@ -1,5 +1,6 @@
 use crate::exec_command::relativize_to_home;
 use crate::exec_command::strip_bash_lc_and_escape;
+use crate::insert_history::word_wrap_lines;
 use crate::slash_command::SlashCommand;
 use crate::text_block::TextBlock;
 use crate::text_formatting::format_and_truncate_tool_result;
@@ -30,7 +31,6 @@ use ratatui::text::Line as RtLine;
 use ratatui::text::Span as RtSpan;
 use ratatui::widgets::Paragraph;
 use ratatui::widgets::WidgetRef;
-use ratatui::widgets::Wrap;
 use std::collections::HashMap;
 use std::io::Cursor;
 use std::path::PathBuf;
@@ -187,11 +187,8 @@ impl HistoryCell {
     }
 
     pub(crate) fn desired_height(&self, width: u16) -> u16 {
-        Paragraph::new(Text::from(self.plain_lines()))
-            .wrap(Wrap { trim: false })
-            .line_count(width)
-            .try_into()
-            .unwrap_or(0)
+        let wrapped = word_wrap_lines(&self.plain_lines(), width);
+        wrapped.len() as u16
     }
 
     pub(crate) fn new_session_info(
@@ -821,9 +818,8 @@ impl HistoryCell {
 
 impl WidgetRef for &HistoryCell {
     fn render_ref(&self, area: Rect, buf: &mut Buffer) {
-        Paragraph::new(Text::from(self.plain_lines()))
-            .wrap(Wrap { trim: false })
-            .render(area, buf);
+        let wrapped = word_wrap_lines(&self.plain_lines(), area.width);
+        Paragraph::new(Text::from(wrapped)).render(area, buf);
     }
 }