Preserve Markdown tables and whitespace when copying TUI responses (#48549)

## Why

Copied table selections became code blocks containing the rendered grid, losing table structure. Stripping trailing whitespace from completed responses also removed Markdown hard breaks and spaces in code.

## What changed

- Reconstruct Markdown tables from selected cells across grid and record layouts, preserving alignment, inline formatting, and list or blockquote nesting.
- Copy a single selected cell as inline content and leave unselected cells empty without adding their text. Escape literal pipes in table code spans and link destinations.
- Preserve trailing whitespace on lines unchanged by assistant directive removal.
- Keep blank rows in copied text without painting newline selection highlights on empty rows.

## Testing

Add regression coverage for wrapped and rewrapped tables, partial selections, empty cells, literal pipes, and separate table and code blocks. Update snapshots for nested tables and selection highlights, and verify completed-response copying preserves hard breaks and code whitespace.

GitOrigin-RevId: 661e4c8331f2737bedff286548f9343bac44e0cb

codex-rs/tui/src/transcript_view/markdown_copy_tests.rs

@@ -7,6 +7,9 @@ use ratatui::buffer::Buffer;
 use ratatui::layout::Rect;
 use std::path::Path;
 
+#[path = "table_copy_tests.rs"]
+mod tables;
+
 #[path = "markdown_element_copy_tests.rs"]
 mod elements;
 
@@ -361,7 +364,7 @@ fn task_lists_and_transformed_tables_keep_their_meaning() {
     );
     let copied = payload(&layout, 0..layout.text().len()).0;
     let html = crate::clipboard_html::render_markdown(&copied);
-    assert!(html.contains("<pre><code>"), "{copied}\n{html}");
+    assert!(html.contains("<table>"), "{copied}\n{html}");
 }
 
 #[test]

codex-rs/tui/src/transcript_view/snapshots/codex_tui__transcript_view__markdown_copy_tests__nested_tables_keep_their_copy_containers.snap

@@ -1,21 +1,18 @@
 ---
 source: tui/src/transcript_view/markdown_copy_tests.rs
-assertion_line: 393
+assertion_line: 460
 expression: "copies.join(\"\\n---\\n\")"
 ---
 Before
 
-> ```
->  A      B
-> ━━━━━  ━━━━━
->  one    two
-> ```
+> | A | B |
+> |---|---|
+> | one | two |
 <p>Before</p>
 <blockquote>
-<pre><code> A      B
-━━━━━  ━━━━━
- one    two
-</code></pre>
+<table><thead><tr><th>A</th><th>B</th></tr></thead><tbody>
+<tr><td>one</td><td>two</td></tr>
+</tbody></table>
 </blockquote>
 
 ---
@@ -23,18 +20,15 @@ Before
 
 - intro
 
-  ```
-   A      B
-  ━━━━━  ━━━━━
-   one    two
-  ```
+  | A | B |
+  |---|---|
+  | one | two |
 <p>Before</p>
 <ul>
 <li>
 <p>intro</p>
-<pre><code> A      B
-━━━━━  ━━━━━
- one    two
-</code></pre>
+<table><thead><tr><th>A</th><th>B</th></tr></thead><tbody>
+<tr><td>one</td><td>two</td></tr>
+</tbody></table>
 </li>
 </ul>

codex-rs/tui/src/transcript_view/snapshots/codex_tui__transcript_view__markdown_copy_tests__table_spillover_keeps_prose_outside_the_literal_table.snap

@@ -1,24 +1,22 @@
 ---
 source: tui/src/transcript_view/markdown_copy_tests.rs
-assertion_line: 358
+assertion_line: 420
 expression: "format!(\"{copied}\\n{}\", crate::clipboard_html::render_markdown(&copied))"
 ---
 **Before**
 
-```
- A      B
-━━━━━  ━━━━━
- one    two
-```
+| A | B |
+|---|---|
+| one | two |
+
 HTML block:
 \<div\>Prose after the table.\</div\>
 
 After
 <p><strong>Before</strong></p>
-<pre><code> A      B
-━━━━━  ━━━━━
- one    two
-</code></pre>
+<table><thead><tr><th>A</th><th>B</th></tr></thead><tbody>
+<tr><td>one</td><td>two</td></tr>
+</tbody></table>
 <p>HTML block:
 &lt;div&gt;Prose after the table.&lt;/div&gt;</p>
 <p>After</p>

codex-rs/tui/src/transcript_view/snapshots/codex_tui__transcript_view__markdown_copy_tests__tables__empty_selected_rows_keep_copy_spacing_without_newline_highlights.snap

@@ -0,0 +1,27 @@
+---
+source: tui/src/transcript_view/table_copy_tests.rs
+assertion_line: 108
+expression: "highlighted.join(\"\\n\")"
+---
+• Before
+  ^^^^^^^
+
+
+   Task      Status         Next step
+  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+  ━━━━━━━━  ━━━━━━━━━━━━━  ━━━━━━━━━━━━━━━━━━━━━━━
+  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   Task 1    Complete       Review results
+  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+  ────────  ─────────────  ───────────────────────
+  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   Task 2    In progress    Finish implementation
+  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+  ────────  ─────────────  ───────────────────────
+  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   Task 3    Planned        Confirm requirements
+  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+
+  After
+  ^^^^^

codex-rs/tui/src/transcript_view/table_copy_tests.rs

@@ -0,0 +1,183 @@
+//! Selection regressions through the real Markdown renderer, layout, and clipboard serializer.
+
+use super::*;
+use pretty_assertions::assert_eq;
+
+const TABLE: &str = "| Task | Status | Next step |\n|---|---|---|\n| Task 1 | Complete | Review results |\n| Task 2 | In progress | Finish implementation |\n| Task 3 | Planned | Confirm requirements |";
+
+#[test]
+fn table_copy_preserves_structure_across_grid_and_record_layouts() {
+    let source = format!(
+        "The project is moving forward, with one task complete and two still to finish.\n\n{TABLE}\n\nThe next priority is to finish Task 2 while gathering the requirements needed to begin Task 3."
+    );
+    for width in [12, 24, 40, 80, 120] {
+        let layout = markdown_layout(&source, width);
+        assert_eq!(
+            payload(&layout, 0..layout.text().len()),
+            (source.clone(), CopyFormat::Markdown),
+            "width {width}"
+        );
+        let rewrapped = layout.rewrap(/*width*/ 17);
+        assert_eq!(
+            payload(&rewrapped, 0..rewrapped.text().len()).0,
+            source,
+            "rewrapped {width}"
+        );
+    }
+}
+
+#[test]
+fn partial_table_selection_never_adds_unselected_cell_text() {
+    let code = markdown_layout(
+        "| A | B |\n|---|---|\n| `a\\|b` | value |",
+        /*width*/ 80,
+    );
+    let start = code.text().find("a|b").unwrap();
+    assert_eq!(payload(&code, start..start + 3).0, "`a|b`");
+    let repeated = markdown_layout(
+        "| alpha SECRET omega |\n|---|\n| long_value_one |\n| long_value_two |",
+        /*width*/ 12,
+    );
+    let start = repeated.text().find("omega").unwrap();
+    let end = repeated.text().rfind("alpha").unwrap() + "alpha".len();
+    assert!(!payload(&repeated, start..end).0.contains("SECRET"));
+    assert!(
+        payload(&repeated, start..repeated.text().len())
+            .0
+            .starts_with("| alpha SECRET omega |")
+    );
+    let layout = markdown_layout(
+        "| Label | Value |\n|---|---|\n| **alpha** | beta |\n| gamma | delta |",
+        /*width*/ 80,
+    );
+    let start = layout.text().find("alpha").unwrap();
+    assert_eq!(
+        payload(&layout, start + 1..start + 4),
+        ("**lph**".into(), CopyFormat::Markdown)
+    );
+    let end = layout.text().find("delta").unwrap() + "delta".len();
+    let copied = payload(&layout, start..end).0;
+    assert_eq!(
+        copied,
+        "|  |  |\n|---|---|\n| **alpha** | beta |\n| gamma | delta |"
+    );
+}
+
+#[test]
+fn table_cells_keep_inline_formatting_alignment_and_literal_pipes() {
+    let source = "| Left | Center | Right |\n|:---|:---:|---:|\n| **bold** _italic_ ~~strike~~ | `a\\|b` | [link](<https://example.com/?a=1&b=2>) |\n| café 界 | escaped \\*star\\* | last |";
+    let expected_html = crate::clipboard_html::render_markdown(
+        &source.replace("[link]", "[link (https://example.com/?a=1&b=2)]"),
+    );
+    for width in [16, 48, 120] {
+        let layout = markdown_layout(source, width);
+        let copied = payload(&layout, 0..layout.text().len()).0;
+        assert_eq!(
+            crate::clipboard_html::render_markdown(&copied),
+            expected_html,
+            "width {width}: {copied}"
+        );
+    }
+}
+
+#[test]
+fn header_only_and_empty_cells_keep_their_table_positions() {
+    for source in [
+        "| A | B |\n|---|---|",
+        "| A |\n|---|",
+        "| A | B |\n|---|---|\n|  | right |\n|  |  |\n| left |  |",
+        "| A | B |\n|---|---|\n| `   ` | value |",
+    ] {
+        for width in [4, 80] {
+            let layout = markdown_layout(source, width);
+            let copied = payload(&layout, 0..layout.text().len()).0;
+            assert_eq!(
+                crate::clipboard_html::render_markdown(&copied),
+                crate::clipboard_html::render_markdown(source),
+                "width {width}: {copied}"
+            );
+        }
+    }
+}
+
+#[test]
+fn separate_tables_and_code_remain_separate_blocks() {
+    let source = "Before\n\n| A | B |\n|---|---|\n| one | two |\n\n```text\n| literal | code |\n```\n\n| C | D |\n|---|---|\n| three | four |\n\nAfter";
+    let layout = markdown_layout(source, /*width*/ 80);
+    let copied = payload(&layout, 0..layout.text().len()).0;
+    assert_eq!(copied, source.replace("```text", "```"));
+}
+
+#[test]
+fn table_separator_only_selection_keeps_visible_text() {
+    for width in [12, 80] {
+        let layout = markdown_layout(TABLE, width);
+        let mut offset = 0;
+        let mut checked = false;
+        for line in layout.text().split('\n') {
+            if line.contains('─') || line.contains('━') {
+                assert_eq!(payload(&layout, offset..offset + line.len()).0, line);
+                checked = true;
+            }
+            offset += line.len() + 1;
+        }
+        assert!(checked, "no separator at width {width}");
+    }
+}
+
+#[test]
+fn empty_selected_rows_keep_copy_spacing_without_newline_highlights() {
+    let cells: Vec<Arc<dyn HistoryCell>> = vec![Arc::new(AgentMarkdownCell::new(
+        format!("Before\n\n{TABLE}\n\nAfter"),
+        Path::new("/"),
+    ))];
+    let mut view = TranscriptView::default();
+    let area = Rect::new(
+        /*x*/ 0, /*y*/ 0, /*width*/ 80, /*height*/ 20,
+    );
+    let mut buffer = Buffer::empty(area);
+    view.render(area, &mut buffer, &cells);
+    view.begin_selection(&cells, /*column*/ 2, /*row*/ 0, /*clicks*/ 1);
+    view.extend_selection(/*column*/ 79, /*row*/ 19);
+    view.render(area, &mut buffer, &cells);
+    let mut highlighted = Vec::new();
+    for row in 0..area.height {
+        let text = (0..area.width)
+            .map(|column| buffer[(column, row)].symbol())
+            .collect::<String>();
+        let selected = (0..area.width)
+            .map(|column| {
+                if buffer[(column, row)]
+                    .modifier
+                    .contains(ratatui::style::Modifier::REVERSED)
+                {
+                    '^'
+                } else {
+                    ' '
+                }
+            })
+            .collect::<String>();
+        if text.trim().is_empty() {
+            assert!(selected.trim().is_empty(), "blank row {row}");
+        }
+        highlighted.push(format!("{}\n{}", text.trim_end(), selected.trim_end()));
+    }
+    let plain = view.selected_text(&cells).unwrap();
+    view.copy_selected_text_with(
+        &cells,
+        &plain,
+        /*clear_selection*/ false,
+        |text, format| {
+            assert_eq!(
+                (text, format),
+                (
+                    format!("Before\n\n{TABLE}\n\nAfter").as_str(),
+                    CopyFormat::Markdown
+                )
+            );
+            Ok(crate::clipboard_copy::CopyStatus::Confirmed)
+        },
+    )
+    .unwrap();
+    insta::assert_snapshot!(highlighted.join("\n"));
+}

codex-rs/tui/src/transcript_view/text.rs

@@ -4,7 +4,7 @@
 //! lines introduce hard breaks. Display wrapping and synthetic controls never enter `text`.
 //! Layout offsets use `usize`; terminal coordinates are narrowed only for visible rows.
 //! Disclosure controls follow their activity's source text without changing its indentation.
-//! Selected hard breaks highlight one trailing cell when space permits.
+//! Selected hard breaks on nonempty rows highlight one trailing cell when space permits.
 
 use std::borrow::Cow;
 use std::ops::Range;
@@ -318,7 +318,7 @@ impl TextLayout {
         }
     }
 
-    /// Add a trailing cell for selected hard breaks, including a copied separator to `next`.
+    /// Mark selected hard breaks on nonempty rows, including a copied separator to `next`.
     pub(super) fn highlight_selection(
         &self,
         range: Range<usize>,
@@ -329,6 +329,9 @@ impl TextLayout {
     ) {
         self.highlight(range.clone(), area, buf, start_row);
         for (screen_row, row) in self.visible_rows(area, start_row) {
+            if row.source.is_empty() {
+                continue;
+            }
             let Some(end) = row.line_end else { continue };
             let selected = range.contains(&end)
                 || (end == self.text.len()

codex-rs/tui/src/transcript_view/text_tests.rs

@@ -113,7 +113,7 @@ fn selection_highlights_wide_graphemes_without_trailing_padding() {
 
 #[test]
 fn selected_newlines_respect_wrapping_and_synthetic_rows() {
-    for (width, expected) in [(8, vec![(2, 2), (6, 5), (2, 6)]), (4, vec![(2, 2), (2, 7)])] {
+    for (width, expected) in [(8, vec![(6, 5)]), (4, vec![])] {
         let layout = TextLayout::new(
             vec!["".into(), "alpha beta  ".into(), "".into(), "界".into()],
             width,