Omit blockquote markers when copying quoted selections in the TUI (#49153)

## Why

Copying text selected within a blockquote adds Markdown quote markers that are not part of the selected content.

## What changed

Return plain text for selections containing only quoted content, preserving literal `>` characters and selected whitespace. For quoted tables and task lists, remove quote prefixes while retaining table reconstruction and checkbox states. Selections spanning quoted and unquoted content continue to preserve Markdown structure.

Preserve the existing logical source when marking list separator lines as omitted from Markdown copying.

## Testing

Add coverage for partial and nested blockquote selections, quoted tables and task lists at narrow and wide widths and after rewrapping, and copying a mouse-selected blockquote.

GitOrigin-RevId: 5ac0c8c47a77937e5a35c376d8908065217ad2dc

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

@@ -423,7 +423,7 @@ fn complete_rules_keep_structure_and_partial_rules_keep_selected_text() {
     let mut copies = Vec::new();
     for (source, partial) in [
         ("Before\n\n---\n\nAfter", "—"),
-        ("Before\n\n> ---\n\nAfter", "> —"),
+        ("Before\n\n> ---\n\nAfter", "—"),
     ] {
         let layout = markdown_layout(source, /*width*/ 80);
         let copied = payload(&layout, 0..layout.text().len()).0;
@@ -461,7 +461,11 @@ fn partial_prose_keeps_leading_whitespace_outside_code_blocks() {
     ] {
         let layout = markdown_layout(source, /*width*/ 80);
         let start = layout.text().find("prefix").unwrap() + "prefix".len();
-        let copied = payload(&layout, start..layout.text().len()).0;
+        let (copied, format) = payload(&layout, start..layout.text().len());
+        if format == CopyFormat::PlainText {
+            copies.push(format!("{copied}\n{format:?}"));
+            continue;
+        }
         copies.push(format!(
             "{copied}\n{}",
             crate::clipboard_html::render_markdown(&copied)
@@ -711,7 +715,14 @@ fn selected_list_and_code_containers_keep_their_structure() {
         let layout = markdown_layout(source, /*width*/ 80);
         let start = layout.text().find(start).expect(source);
         let end = layout.text().rfind(end).expect(source) + end.len();
-        let copied = payload(&layout, start..end).0;
+        let (copied, format) = payload(&layout, start..end);
+        if source.starts_with('>') {
+            assert_eq!(
+                (copied.as_str(), format),
+                (&layout.text()[start..end], CopyFormat::PlainText)
+            );
+            continue;
+        }
         assert_eq!(
             crate::clipboard_html::render_markdown(&copied),
             crate::clipboard_html::render_markdown(expected),

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

@@ -12,7 +12,7 @@ fn supported_elements_preserve_structure_at_narrow_and_wide_widths() {
         "Escaped \\*stars\\*, & entity, café 界, and 👩‍💻.",
         "- first\n- second\n  - nested\n\n3. third\n4. fourth",
         "- [ ] pending\n- [x] complete",
-        "> quoted **text**\n>\n> - item\n>   - nested",
+        "Before\n\n> quoted **text**\n>\n> - item\n>   - nested\n\nAfter",
         "First paragraph.\n\nHard break:  \nnext line.\n\n---\n\nLast paragraph.",
         "Prose\n\n```\nlet x = \"*literal* <tag>\";\n```\n\nAfter",
         "Image ![**alt** text](https://example.com/image.png).",
@@ -73,3 +73,161 @@ fn math_and_mermaid_copy_the_visible_rendering() {
         }
     }
 }
+
+#[test]
+fn blockquote_selection_copies_only_selected_content() {
+    let mut copies = Vec::new();
+    for (source, selected) in [
+        ("> quoted text", "quoted text"),
+        ("> quoted text", "quoted"),
+        ("> quoted text", "text"),
+        ("> first line\n> second line", "first line\nsecond line"),
+        (
+            "> first paragraph\n>\n> second paragraph",
+            "first paragraph\n\nsecond paragraph",
+        ),
+        (
+            "> outer\n>> nested café界\n>\n> outer again",
+            "outer\n\nnested café界\n\nouter again",
+        ),
+        ("> **bold** and `code`", "bold and code"),
+        ("> **bold**\n>\n> - [x] task", "bold\n\n"),
+        ("> **bold**\n>\n> | A |\n> |---|\n> | cell |", "bold\n\n"),
+        (
+            "> literal \\> marker and a > b",
+            "literal > marker and a > b",
+        ),
+        ("Before\n\n> quoted text\n\nAfter", "quoted text"),
+        ("Before\n\n> quoted text\n\nAfter", "quoted text\n"),
+        ("Before\n\n> quoted text\n\nAfter", "\nquoted text"),
+        (
+            "> - first\n>   continuation\n> - second",
+            "first\ncontinuation\n\nsecond",
+        ),
+    ] {
+        for width in [18, 80] {
+            let layout = markdown_layout(source, width);
+            let start = layout.text().find(selected).expect(source);
+            let copied = payload(&layout, start..start + selected.len());
+            assert_eq!(copied, (selected.into(), CopyFormat::PlainText), "{source}");
+            assert_eq!(
+                payload(&layout.rewrap(/*width*/ 12), start..start + selected.len()),
+                copied
+            );
+            if width == 80 && copies.len() < 3 {
+                copies.push(format!("{source}\nSelected {selected:?} -> {copied:?}"));
+            }
+        }
+    }
+    insta::assert_snapshot!(copies.join("\n"), @r#"
+    > quoted text
+    Selected "quoted text" -> ("quoted text", PlainText)
+    > quoted text
+    Selected "quoted" -> ("quoted", PlainText)
+    > quoted text
+    Selected "text" -> ("text", PlainText)
+    "#);
+}
+
+#[test]
+fn quoted_tables_reconstruct_wrapped_cell_values() {
+    let table = "| Path |\n|---|\n| `/long/path/to/a/file/with_a_long_name.rs` |";
+    for prefix in ["> ", "> > "] {
+        let source = table
+            .lines()
+            .map(|line| format!("{prefix}{line}"))
+            .collect::<Vec<_>>()
+            .join("\n");
+        for width in [18, 80] {
+            let layout = markdown_layout(&source, width);
+            let copied = payload(&layout, 0..layout.text().len());
+            assert_eq!(copied, (table.into(), CopyFormat::Markdown));
+            let start = layout.text().find("/long").unwrap();
+            let end = layout.text().rfind(".rs").unwrap() + 3;
+            let cell = payload(&layout, start..end);
+            assert_eq!(
+                cell,
+                (
+                    "/long/path/to/a/file/with_a_long_name.rs".into(),
+                    CopyFormat::PlainText
+                )
+            );
+            let rewrapped = layout.rewrap(/*width*/ 12);
+            assert_eq!(payload(&rewrapped, start..end), cell);
+            assert_eq!(payload(&rewrapped, 0..rewrapped.text().len()), copied);
+        }
+    }
+}
+
+#[test]
+fn quoted_task_lists_preserve_checkbox_states() {
+    for (source, expected) in [
+        (
+            "> - [x] Tests passed\n> - [ ] Deploy",
+            "- [x] Tests passed\n- [ ] Deploy",
+        ),
+        (
+            "> > 1. [ ] Tests passed\n> > 2. [x] Deploy",
+            "1. [ ] Tests passed\n2. [x] Deploy",
+        ),
+        ("> - [x] \n> - ordinary", "- [x]\n- ordinary"),
+        ("> - ordinary\n> - [ ] ", "- ordinary\n- [ ]"),
+    ] {
+        for width in [18, 80] {
+            let layout = markdown_layout(source, width);
+            let copied = payload(&layout, 0..layout.text().len());
+            assert_eq!(copied, (expected.into(), CopyFormat::Markdown));
+            let rewrapped = layout.rewrap(/*width*/ 12);
+            assert_eq!(payload(&rewrapped, 0..rewrapped.text().len()), copied);
+            if width == 80 && source.starts_with("> - [x] Tests") {
+                insta::assert_snapshot!(copied.0, @"
+                - [x] Tests passed
+                - [ ] Deploy
+                ");
+            }
+        }
+    }
+}
+
+#[test]
+fn mouse_selected_blockquote_copies_without_markers() {
+    use crossterm::event::KeyModifiers;
+    use crossterm::event::MouseButton;
+    use crossterm::event::MouseEvent;
+    use crossterm::event::MouseEventKind;
+
+    let cells: Vec<Arc<dyn HistoryCell>> = vec![Arc::new(AgentMarkdownCell::new(
+        "> quoted text".into(),
+        Path::new("/"),
+    ))];
+    let mut view = TranscriptView::default();
+    let area = Rect::new(
+        /*x*/ 0, /*y*/ 0, /*width*/ 32, /*height*/ 10,
+    );
+    view.render(area, &mut Buffer::empty(area), &cells);
+    for (kind, column) in [
+        (MouseEventKind::Down(MouseButton::Left), 0),
+        (MouseEventKind::Drag(MouseButton::Left), 31),
+    ] {
+        view.handle_mouse(
+            MouseEvent {
+                kind,
+                column,
+                row: 0,
+                modifiers: KeyModifiers::NONE,
+            },
+            &cells,
+        );
+    }
+    let plain = view.selected_text(&cells).unwrap();
+    view.copy_selected_text_with(
+        &cells,
+        &plain,
+        /*clear_selection*/ true,
+        |text, format| {
+            assert_eq!((text, format), ("quoted text", CopyFormat::PlainText));
+            Ok(crate::clipboard_copy::CopyStatus::Confirmed)
+        },
+    )
+    .unwrap();
+}

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

@@ -1,6 +1,5 @@
 ---
 source: tui/src/transcript_view/markdown_copy_tests.rs
-assertion_line: 379
 expression: "copies.join(\"\\n---\\n\")"
 ---
     suffix
@@ -15,5 +14,5 @@ expression: "copies.join(\"\\n---\\n\")"
 <p>    <strong>suffix</strong></p>
 
 ---
-&#32;&#32;&#32;&#32;suffix
-<p>    suffix</p>
+    suffix
+PlainText