Documents: untouched cells keep their bytes; open cells take padding presses

A trailing backslash doubles only before a closing pipe. A write at a
block's start keeps the block, so Tab leaves a first cell without outer
pipes. Padding of the open cell moves its caret to the end, and a right
press there points at the end.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/documents/document/apart.rs

@@ -132,9 +132,10 @@ impl MarkdownDocument {
         // A cell reads as it writes back.
         let typed = match open.cell {
             Some(_) => {
-                let shift = |at: usize| cells::kept_at(typed, at);
+                let closed = cells::closed(text, open.range.end);
+                let shift = |at: usize| cells::kept_at(typed, at, closed);
                 picked = shift(picked.start)..shift(picked.end);
-                cells::kept(typed)
+                cells::kept(typed, closed)
             }
             None => typed.to_string(),
         };
@@ -156,7 +157,8 @@ impl MarkdownDocument {
         if let Some(open) = &self.open {
             let typed = open.input.read(cx).text();
             // Offsets read the escaped cell; its field holds it raw.
-            let raw = open.cell.is_some() && cells::kept(typed) != typed;
+            let closed = cells::closed(self.editor.read(cx).text(), open.range.end);
+            let raw = open.cell.is_some() && cells::kept(typed, closed) != typed;
             let end = offset + typed.len();
             let grown = (edits.iter().map(|(_, with)| with.len()).sum::<usize>() + end)
                 .checked_sub(edits.iter().map(|(range, _)| range.len()).sum::<usize>());

src/documents/document/cells.rs

@@ -157,27 +157,32 @@ fn guarded(typed: &str) -> String {
     out
 }
 
-/// `typed` as a cell keeps it, its closing pipe intact.
-pub(super) fn kept(typed: &str) -> String {
+/// Whether a pipe follows the cell source ending at `end`.
+pub(super) fn closed(text: &str, end: usize) -> bool {
+    text[end..].starts_with('|')
+}
+
+/// `typed` as a cell keeps it, a `closed` pipe intact.
+pub(super) fn kept(typed: &str, closed: bool) -> String {
     let mut out = guarded(typed);
     let slashes = out.len() - out.trim_end_matches('\\').len();
-    if slashes % 2 == 1 {
+    if closed && slashes % 2 == 1 {
         out.push('\\');
     }
     out
 }
 
-/// Byte `at` of `typed` within `kept(typed)`.
-pub(super) fn kept_at(typed: &str, at: usize) -> usize {
+/// Byte `at` of `typed` within `kept(typed, closed)`.
+pub(super) fn kept_at(typed: &str, at: usize, closed: bool) -> usize {
     match at == typed.len() {
-        true => kept(typed).len(),
+        true => kept(typed, closed).len(),
         false => guarded(&typed[..at]).len(),
     }
 }
 
 #[cfg(test)]
 mod tests {
-    use super::{Aim, CellAt, Move, beside, find, guarded, kept, kept_at};
+    use super::{Aim, CellAt, Move, beside, closed, find, guarded, kept, kept_at};
 
     const TABLE: &str = "intro\n\n| a | **b** |\n| --- | --- |\n| c |  |\n| d | e |\n";
 
@@ -239,15 +244,16 @@ mod tests {
 
     #[test]
     fn a_closing_backslash_keeps_the_next_pipe() {
-        assert_eq!(kept("a\\"), "a\\\\");
-        assert_eq!(kept("a\\\\"), "a\\\\");
-        assert_eq!(kept_at("a\\", 2), 3);
-        assert_eq!(kept_at("a\\b", 2), 2);
+        assert_eq!(kept("a\\", true), "a\\\\");
+        assert_eq!(kept("a\\\\", true), "a\\\\");
+        assert_eq!(kept_at("a\\", 2, true), 3);
+        assert_eq!(kept_at("a\\b", 2, true), 2);
         let text = "|a|b|\n|---|---|\n|c|d|\n";
         let cell = find(text, 0..text.len() - 1, Aim::First).expect("a cell");
+        let shut = closed(text, cell.range.end);
         let written = [
             &text[..cell.range.start],
-            &kept("a\\"),
+            &kept("a\\", shut),
             &text[cell.range.end..],
         ]
         .concat();
@@ -255,8 +261,17 @@ mod tests {
         assert_eq!(&written[b.range], "b");
     }
 
+    #[test]
+    fn a_backslash_before_padding_stays_single() {
+        let text = "| a\\ | b |\n| --- | --- |\n";
+        let cell = find(text, 0..text.len() - 1, Aim::First).expect("a cell");
+        assert_eq!(&text[cell.range.clone()], "a\\");
+        assert!(!closed(text, cell.range.end));
+        assert_eq!(kept("a\\", false), "a\\");
+    }
+
     #[test]
     fn typed_pipes_shift_later_bytes() {
-        assert_eq!(kept_at("||x", 2), 4);
+        assert_eq!(kept_at("||x", 2, false), 4);
     }
 }

src/documents/document/edit.rs

@@ -31,7 +31,7 @@ pub(super) enum Landing {
 pub(super) fn moved(at: usize, edit: &Option<(Range<usize>, usize)>) -> Option<usize> {
     match edit {
         None => Some(at),
-        Some((replaced, _)) if at < replaced.start => Some(at),
+        Some((replaced, _)) if at <= replaced.start => Some(at),
         Some((replaced, written)) if at >= replaced.end => Some(at - replaced.len() + written),
         Some(_) => None,
     }
@@ -231,14 +231,15 @@ impl MarkdownDocument {
         let typed = open.input.read(cx).text().to_string();
         let caret = open.input.read(cx).cursor();
         let text = self.editor.read(cx).text();
+        let closed = cells::closed(text, open.range.end);
         let (lead, written) = match open.append {
             true if typed.is_empty() => return None,
             true => (joint(text).len(), format!("{}{typed}", joint(text))),
-            false if open.cell.is_some() => (0, cells::kept(&typed)),
+            false if open.cell.is_some() => (0, cells::kept(&typed, closed)),
             false => (0, typed.clone()),
         };
         let caret = match open.cell {
-            Some(_) => cells::kept_at(&typed, caret),
+            Some(_) => cells::kept_at(&typed, caret, closed),
             None => caret,
         };
         let at = open.range.start + lead + caret;
@@ -303,6 +304,7 @@ mod tests {
         let edit = Some((2..6, 9));
         assert_eq!(super::moved(10, &edit), Some(15));
         assert_eq!(super::moved(1, &edit), Some(1), "before stays");
+        assert_eq!(super::moved(2, &edit), Some(2), "its start stays");
         assert_eq!(super::moved(3, &edit), None, "inside is gone");
         assert_eq!(super::moved(7, &None), Some(7));
     }

src/documents/document/mod.rs

@@ -246,7 +246,7 @@ impl MarkdownDocument {
         let written = match open.append {
             true if typed.is_empty() => String::new(),
             true => format!("{}{typed}", joint(text)),
-            false if open.cell.is_some() => cells::kept(typed),
+            false if open.cell.is_some() => cells::kept(typed, cells::closed(text, open.range.end)),
             false => typed.to_string(),
         };
         [&text[..open.range.start], &written, &text[open.range.end..]].concat()

src/documents/document/point.rs

@@ -1,6 +1,6 @@
-use std::rc::Rc;
+use std::{ops::Range, rc::Rc};
 
-use gpui::{AppContext as _, Context, MouseButton, Pixels, Point, Window};
+use gpui::{AppContext as _, Context, Focusable as _, MouseButton, Pixels, Point, Window};
 use markdown::mdast;
 
 use super::{
@@ -12,7 +12,7 @@ use super::{
 };
 use crate::documents::{
     markdown::{file_tree, span, walk},
-    render::{OnPoint, Place, Pointed},
+    render::{CellAt, OnPoint, Place, Pointed},
     tree::{Node, Reader, alert, is_toc, lines_at},
 };
 
@@ -102,15 +102,44 @@ impl MarkdownDocument {
             };
             let ix = Some(ix);
             document
-                .update(cx, |document, cx| match button {
-                    MouseButton::Left => document.open(ix, landing, window, cx),
-                    MouseButton::Right => document.point(ix, at, pointed, window, cx),
-                    _ => {}
+                .update(cx, |document, cx| {
+                    // The open cell's padding keeps its typing.
+                    let open = match pointed.place {
+                        Place::Cell(cell) => document.open_cell(&block) == Some(cell),
+                        _ => false,
+                    };
+                    match (button, open) {
+                        (MouseButton::Left, true) => document.cell_end(window, cx),
+                        (MouseButton::Right, true) => document.point_open(None, cx),
+                        (MouseButton::Left, false) => document.open(ix, landing, window, cx),
+                        (MouseButton::Right, false) => document.point(ix, at, pointed, window, cx),
+                        _ => {}
+                    }
                 })
                 .expect("a block's drawing lives in its document");
         })
     }
 
+    /// The cell open in `block`, if any.
+    fn open_cell(&self, block: &Range<usize>) -> Option<CellAt> {
+        let open = self.open.as_ref()?;
+        let inside = block.start <= open.range.start && open.range.end <= block.end;
+        open.cell.filter(|_| inside)
+    }
+
+    /// Caret to the open cell's end.
+    fn cell_end(&mut self, window: &mut Window, cx: &mut Context<Self>) {
+        let Some(open) = &self.open else {
+            return;
+        };
+        let input = open.input.clone();
+        input.update(cx, |input, cx| {
+            let end = input.text().len();
+            input.select(end..end, cx);
+        });
+        window.focus(&input.focus_handle(cx), cx);
+    }
+
     /// A block's kind, text and what it draws.
     fn drawn(&self, block: &Block) -> (TargetBlock, String, Option<Vec<Node>>) {
         let text = self.parsed.text[block.range.clone()].to_string();
@@ -178,16 +207,22 @@ impl MarkdownDocument {
         cx.notify();
     }
 
-    /// A right press at `position`; the open block stays open.
-    pub(super) fn point_open(&mut self, position: Point<Pixels>, cx: &mut Context<Self>) {
+    /// A right press at `position`, else at the field's end.
+    pub(super) fn point_open(&mut self, position: Option<Point<Pixels>>, cx: &mut Context<Self>) {
         let Some(open) = &self.open else {
             return log::warn!("markdown document: a press on a block closed since");
         };
         let input = open.input.read(cx);
-        let pressed = input.offset_for_point(position);
+        let pressed = match position {
+            Some(position) => input.offset_for_point(position),
+            None => input.text().len(),
+        };
         // A cell's typed pipes shift its bytes.
         let pressed = match open.cell {
-            Some(_) => cells::kept_at(input.text(), pressed),
+            Some(_) => {
+                let closed = cells::closed(self.editor.read(cx).text(), open.range.end);
+                cells::kept_at(input.text(), pressed, closed)
+            }
             None => pressed,
         };
         let taken = self.snapshot(cx);

src/documents/document/tests/cells.rs

@@ -171,3 +171,73 @@ fn a_right_press_on_a_cell_points_at_it(cx: &mut TestAppContext) {
     let at = heard.borrow().last().expect("heard").at;
     assert_eq!(at, WORDS.rfind(" d").expect("the cell") + 2);
 }
+
+#[gpui::test]
+fn an_untouched_backslash_cell_keeps_its_bytes(cx: &mut TestAppContext) {
+    let table = "| a\\ | b |\n| --- | --- |\n| c | d |\n";
+    let (document, cx) = open(table, MarkdownMode::Visual, cx);
+    press_cell(0, 0, cx);
+    assert_eq!(opened(&document, cx), "a\\");
+    document.update_in(cx, |document, window, cx| {
+        document.set_mode(MarkdownMode::Source, window, cx)
+    });
+    assert_eq!(text(&document, cx), table);
+}
+
+const BARE: &str = "alpha | beta\n--- | ---\nc | d\n";
+
+#[gpui::test]
+fn tab_leaves_an_edited_first_cell_without_outer_pipes(cx: &mut TestAppContext) {
+    let (document, cx) = open(BARE, MarkdownMode::Visual, cx);
+    press_cell(0, 0, cx);
+    cx.simulate_input("X");
+    cx.simulate_keystrokes("tab");
+    assert_eq!(opened(&document, cx), "beta");
+    assert_eq!(text(&document, cx), "alphaX | beta\n--- | ---\nc | d\n");
+}
+
+#[gpui::test]
+fn a_neighbour_press_leaves_an_edited_first_cell(cx: &mut TestAppContext) {
+    let (document, cx) = open(BARE, MarkdownMode::Visual, cx);
+    press_cell(0, 0, cx);
+    cx.simulate_input("X");
+    press_cell(0, 1, cx);
+    assert_eq!(opened(&document, cx), "beta");
+}
+
+#[gpui::test]
+fn the_open_cells_padding_lands_at_its_end_in_one_step(cx: &mut TestAppContext) {
+    let (document, cx) = open(WORDS, MarkdownMode::Visual, cx);
+    press_cell(0, 0, cx);
+    cx.simulate_input("X");
+    let x = x_of(&document, 1, cx);
+    press_field(x, MouseButton::Left, cx);
+    assert_eq!(caret(&document, cx), 1);
+    press_cell(0, 0, cx);
+    assert_eq!(caret(&document, cx), 6, "the padding lands at the end");
+    cx.simulate_input("Y");
+    cx.simulate_keystrokes("escape");
+    assert_eq!(
+        text(&document, cx),
+        "| alphaXY | beta |\n| --- | --- |\n| c | d |\n"
+    );
+    let editor = document.read_with(cx, |document, _| document.editor().clone());
+    editor.update(cx, |editor, cx| editor.undo(cx));
+    assert_eq!(text(&document, cx), WORDS);
+}
+
+#[gpui::test]
+fn a_right_press_on_the_open_cells_padding_points_at_its_end(cx: &mut TestAppContext) {
+    let (document, cx) = open(WORDS, MarkdownMode::Visual, cx);
+    let heard = heard(&document, cx);
+    press_cell(0, 0, cx);
+    cx.simulate_input("||");
+    press_cell_with(0, 0, MouseButton::Right, cx);
+    let target = heard.borrow().last().cloned().expect("heard");
+    assert!(target.in_table);
+    assert_eq!(
+        target.at,
+        WORDS.find("alpha").expect("the cell") + "alpha\\|\\|".len()
+    );
+    assert_eq!(opened(&document, cx), "alpha||", "the cell stays open");
+}

src/documents/document/tests/secondary.rs

@@ -176,8 +176,8 @@ fn only_the_latest_press_in_an_open_block_is_heard(cx: &mut TestAppContext) {
         })
     });
     document.update(cx, |document, cx| {
-        document.point_open(spots[0], cx);
-        document.point_open(spots[1], cx);
+        document.point_open(Some(spots[0]), cx);
+        document.point_open(Some(spots[1]), cx);
     });
     cx.run_until_parked();
     let links: Vec<_> = (heard.borrow().iter())

src/documents/document/visual.rs

@@ -175,7 +175,7 @@ impl MarkdownDocument {
         cx.listener(|document, event: &MouseDownEvent, window, cx| {
             window.prevent_default();
             cx.stop_propagation();
-            document.point_open(event.position, cx);
+            document.point_open(Some(event.position), cx);
         })
     }
 

src/documents/render/table.rs

@@ -59,24 +59,21 @@ impl Draw<'_> {
                     cell.font_weight(FontWeight::MEDIUM)
                         .text_color(colors.fg_muted)
                 });
-            match open {
-                // Presses in the open cell stay with its field.
-                Some(field) => drawn
-                    .child(div().w_full().child(field))
+            let inside = match open {
+                // Presses on the open field stay with it.
+                Some(field) => div()
+                    .w_full()
+                    .child(field)
                     .on_mouse_down(MouseButton::Left, |_, _, cx| cx.stop_propagation())
                     .on_mouse_down(MouseButton::Right, |_, _, cx| cx.stop_propagation()),
-                None => self.pressed_cell(
-                    drawn.child(
-                        div()
-                            .max_w_full()
-                            .flex()
-                            .flex_col()
-                            .gap_1()
-                            .children(self.nodes(blocks, cx)),
-                    ),
-                    at,
-                ),
-            }
+                None => div()
+                    .max_w_full()
+                    .flex()
+                    .flex_col()
+                    .gap_1()
+                    .children(self.nodes(blocks, cx)),
+            };
+            self.pressed_cell(drawn.child(inside), at)
         };
         div()
             .flex()