fix(tui): propagate errors in insert_history_lines_to_writer (#4266)

## What?
Fixed error handling in `insert_history_lines_to_writer` where all
terminal operations were silently ignoring errors via `.ok()`.

  ## Why?
Silent I/O failures could leave the terminal in an inconsistent state
(e.g., scroll region not reset) with no way to debug. This violates Rust
error handling best practices.

  ## How?
  - Changed function signature to return `io::Result<()>`
  - Replaced all `.ok()` calls with `?` operator to propagate errors
- Added `tracing::warn!` in wrapper function for backward compatibility
  - Updated 15 test call sites to handle Result  with `.expect()`

  ## Testing
  - ✅ Pass all tests

  ## Type of Change
  - [x] Bug fix (non-breaking change)

---------

Signed-off-by: Huaiwu Li <lhwzds@gmail.com>
Co-authored-by: Eric Traut <etraut@openai.com>

codex-rs/tui/src/chatwidget/tests.rs

@@ -1582,7 +1582,8 @@ async fn binary_size_transcript_snapshot() {
                             }
                             has_emitted_history = true;
                             transcript.push_str(&lines_to_single_string(&lines));
-                            crate::insert_history::insert_history_lines(&mut terminal, lines);
+                            crate::insert_history::insert_history_lines(&mut terminal, lines)
+                                .expect("Failed to insert history lines in test");
                         }
                     }
                 }
@@ -1603,7 +1604,8 @@ async fn binary_size_transcript_snapshot() {
                             }
                             has_emitted_history = true;
                             transcript.push_str(&lines_to_single_string(&lines));
-                            crate::insert_history::insert_history_lines(&mut terminal, lines);
+                            crate::insert_history::insert_history_lines(&mut terminal, lines)
+                                .expect("Failed to insert history lines in test");
                         }
                     }
                 }
@@ -2654,7 +2656,8 @@ fn chatwidget_exec_and_status_layout_vt100_snapshot() {
     term.set_viewport_area(viewport);
 
     for lines in drain_insert_history(&mut rx) {
-        crate::insert_history::insert_history_lines(&mut term, lines);
+        crate::insert_history::insert_history_lines(&mut term, lines)
+            .expect("Failed to insert history lines in test");
     }
 
     term.draw(|f| {
@@ -2731,7 +2734,8 @@ printf 'fenced within fenced\n'
             while let Ok(app_ev) = rx.try_recv() {
                 if let AppEvent::InsertHistoryCell(cell) = app_ev {
                     let lines = cell.display_lines(width);
-                    crate::insert_history::insert_history_lines(&mut term, lines);
+                    crate::insert_history::insert_history_lines(&mut term, lines)
+                        .expect("Failed to insert history lines in test");
                     inserted_any = true;
                 }
             }
@@ -2749,7 +2753,8 @@ printf 'fenced within fenced\n'
         }),
     });
     for lines in drain_insert_history(&mut rx) {
-        crate::insert_history::insert_history_lines(&mut term, lines);
+        crate::insert_history::insert_history_lines(&mut term, lines)
+            .expect("Failed to insert history lines in test");
     }
 
     assert_snapshot!(term.backend().vt100().screen().contents());

codex-rs/tui/src/insert_history.rs

@@ -24,7 +24,10 @@ use ratatui::text::Span;
 
 /// Insert `lines` above the viewport using the terminal's backend writer
 /// (avoids direct stdout references).
-pub fn insert_history_lines<B>(terminal: &mut crate::custom_terminal::Terminal<B>, lines: Vec<Line>)
+pub fn insert_history_lines<B>(
+    terminal: &mut crate::custom_terminal::Terminal<B>,
+    lines: Vec<Line>,
+) -> io::Result<()>
 where
     B: Backend + Write,
 {
@@ -51,13 +54,13 @@ where
         //   3) Emitting Reverse Index (RI, ESC M) `scroll_amount` times
         //   4) Resetting the scroll region back to full screen
         let top_1based = area.top() + 1; // Convert 0-based row to 1-based for DECSTBM
-        queue!(writer, SetScrollRegion(top_1based..screen_size.height)).ok();
+        queue!(writer, SetScrollRegion(top_1based..screen_size.height))?;
-        queue!(writer, MoveTo(0, area.top())).ok();
+        queue!(writer, MoveTo(0, area.top()))?;
         for _ in 0..scroll_amount {
             // Reverse Index (RI): ESC M
-            queue!(writer, Print("\x1bM")).ok();
+            queue!(writer, Print("\x1bM"))?;
         }
-        queue!(writer, ResetScrollRegion).ok();
+        queue!(writer, ResetScrollRegion)?;
 
         let cursor_top = area.top().saturating_sub(1);
         area.y += scroll_amount;
@@ -82,15 +85,15 @@ where
     // ││                            ││
     // │╰────────────────────────────╯│
     // └──────────────────────────────┘
-    queue!(writer, SetScrollRegion(1..area.top())).ok();
+    queue!(writer, SetScrollRegion(1..area.top()))?;
 
     // NB: we are using MoveTo instead of set_cursor_position here to avoid messing with the
     // terminal's last_known_cursor_position, which hopefully will still be accurate after we
     // fetch/restore the cursor position. insert_history_lines should be cursor-position-neutral :)
-    queue!(writer, MoveTo(0, cursor_top)).ok();
+    queue!(writer, MoveTo(0, cursor_top))?;
 
     for line in wrapped {
-        queue!(writer, Print("\r\n")).ok();
+        queue!(writer, Print("\r\n"))?;
         queue!(
             writer,
             SetColors(Colors::new(
@@ -103,9 +106,8 @@ where
                     .map(std::convert::Into::into)
                     .unwrap_or(CColor::Reset)
             ))
-        )
+        )?;
-        .ok();
+        queue!(writer, Clear(ClearType::UntilNewLine))?;
-        queue!(writer, Clear(ClearType::UntilNewLine)).ok();
         // Merge line-level style into each span so that ANSI colors reflect
         // line styles (e.g., blockquotes with green fg).
         let merged_spans: Vec<Span> = line
@@ -116,18 +118,20 @@ where
                 content: s.content.clone(),
             })
             .collect();
-        write_spans(writer, merged_spans.iter()).ok();
+        write_spans(writer, merged_spans.iter())?;
     }
 
-    queue!(writer, ResetScrollRegion).ok();
+    queue!(writer, ResetScrollRegion)?;
 
     // Restore the cursor position to where it was before we started.
-    queue!(writer, MoveTo(last_cursor_pos.x, last_cursor_pos.y)).ok();
+    queue!(writer, MoveTo(last_cursor_pos.x, last_cursor_pos.y))?;
 
     let _ = writer;
     if should_update_area {
         terminal.set_viewport_area(area);
     }
+
+    Ok(())
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -328,7 +332,8 @@ mod tests {
         // Build a blockquote-like line: apply line-level green style and prefix "> "
         let mut line: Line<'static> = Line::from(vec!["> ".into(), "Hello world".into()]);
         line = line.style(Color::Green);
-        insert_history_lines(&mut term, vec![line]);
+        insert_history_lines(&mut term, vec![line])
+            .expect("Failed to insert history lines in test");
 
         let mut saw_colored = false;
         'outer: for row in 0..height {
@@ -366,7 +371,8 @@ mod tests {
         ]);
         line = line.style(Color::Green);
 
-        insert_history_lines(&mut term, vec![line]);
+        insert_history_lines(&mut term, vec![line])
+            .expect("Failed to insert history lines in test");
 
         // Parse and inspect the final screen buffer.
         let screen = term.backend().vt100().screen();
@@ -428,7 +434,8 @@ mod tests {
             Span::raw("Hello world"),
         ]);
 
-        insert_history_lines(&mut term, vec![line]);
+        insert_history_lines(&mut term, vec![line])
+            .expect("Failed to insert history lines in test");
 
         let screen = term.backend().vt100().screen();
 
@@ -484,7 +491,7 @@ mod tests {
         let viewport = ratatui::layout::Rect::new(0, height - 1, width, 1);
         term.set_viewport_area(viewport);
 
-        insert_history_lines(&mut term, lines);
+        insert_history_lines(&mut term, lines).expect("Failed to insert history lines in test");
 
         let screen = term.backend().vt100().screen();
 

codex-rs/tui/src/tui.rs

@@ -548,7 +548,7 @@ impl Tui {
                 crate::insert_history::insert_history_lines(
                     terminal,
                     self.pending_history_lines.clone(),
-                );
+                )?;
                 self.pending_history_lines.clear();
             }
             // Update the y position for suspending so Ctrl-Z can place the cursor correctly.

codex-rs/tui/tests/suite/vt100_history.rs

@@ -36,7 +36,8 @@ impl TestScenario {
     }
 
     fn run_insert(&mut self, lines: Vec<Line<'static>>) {
-        codex_tui::insert_history::insert_history_lines(&mut self.term, lines);
+        codex_tui::insert_history::insert_history_lines(&mut self.term, lines)
+            .expect("Failed to insert history lines in test");
     }
 }
 

codex-rs/tui/tests/suite/vt100_live_commit.rs

@@ -26,7 +26,8 @@ fn live_001_commit_on_overflow() {
     let commit_rows = rb.drain_commit_ready(3);
     let lines: Vec<Line<'static>> = commit_rows.into_iter().map(|r| r.text.into()).collect();
 
-    codex_tui::insert_history::insert_history_lines(&mut term, lines);
+    codex_tui::insert_history::insert_history_lines(&mut term, lines)
+        .expect("Failed to insert history lines in test");
 
     let screen = term.backend().vt100().screen();