documents: undo and redo leave a block only past its own history; typing lands after undo empties the document

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

src/documents/document/edit.rs

@@ -23,19 +23,19 @@ fn moved(at: usize, edit: &Option<(Range<usize>, usize)>) -> Option<usize> {
 }
 
 impl MarkdownDocument {
-    /// An empty visual document takes typing at once.
+    /// An empty, read visual document takes typing at once.
     pub(super) fn focused(&mut self, window: &mut Window, cx: &mut Context<Self>) {
-        let empty = self.editor.read(cx).text().trim().is_empty();
+        let empty = self.editor.read(cx).text().trim().is_empty() && self.read_now(cx);
         if self.mode == MarkdownMode::Visual && self.open.is_none() && empty {
             self.open(None, false, window, cx);
         }
     }
 
-    /// The open block still holds what it opened with.
-    pub(super) fn untouched(&self, cx: &App) -> bool {
-        self.open.as_ref().is_some_and(|open| {
-            open.input.read(cx).text() == &self.editor.read(cx).text()[open.range.clone()]
-        })
+    /// The open block has no step left that way.
+    pub(super) fn at_edge_of_history(&self, redo: bool, cx: &App) -> bool {
+        self.open
+            .as_ref()
+            .is_some_and(|open| !open.input.read(cx).can_step(redo))
     }
 
     /// Undo or redo in the document's one history.
@@ -46,7 +46,8 @@ impl MarkdownDocument {
             false => editor.undo(cx),
         });
         window.focus(&self.focus, cx);
-        self.focused(window, cx);
+        // Once the change is read, an empty end opens.
+        cx.defer_in(window, |document, window, cx| document.focused(window, cx));
     }
 
     /// Opens block `ix` as shown, or one past the end.

src/documents/document/tests/history.rs

@@ -0,0 +1,115 @@
+use gpui::{Entity, Modifiers, TestAppContext, VisualTestContext};
+
+use super::{MarkdownDocument, MarkdownMode, TEXT, open, opened, press, text};
+
+/// Focus on `document`'s own handle, as an owner gives it.
+fn focus(document: &Entity<MarkdownDocument>, cx: &mut VisualTestContext) {
+    let handle = document.read_with(cx, |document, cx| {
+        gpui::Focusable::focus_handle(document, cx)
+    });
+    cx.update(|window, cx| window.focus(&handle, cx));
+    cx.run_until_parked();
+}
+
+#[gpui::test]
+fn an_empty_visual_document_takes_typing_on_focus(cx: &mut TestAppContext) {
+    let (document, cx) = open("", MarkdownMode::Visual, cx);
+    focus(&document, cx);
+    cx.simulate_input("Hi");
+    assert_eq!(text(&document, cx), "Hi", "typing lands with no press");
+    cx.simulate_keystrokes("escape");
+    cx.run_until_parked();
+    assert_eq!(text(&document, cx), "Hi", "escape keeps it");
+}
+
+#[gpui::test]
+fn focus_opens_no_block_in_a_written_document(cx: &mut TestAppContext) {
+    let (document, cx) = open(TEXT, MarkdownMode::Visual, cx);
+    focus(&document, cx);
+    cx.simulate_input("x");
+    assert_eq!(text(&document, cx), TEXT);
+}
+
+fn mode(document: &Entity<MarkdownDocument>, mode: MarkdownMode, cx: &mut VisualTestContext) {
+    document.update_in(cx, |document, window, cx| {
+        document.set_mode(mode, window, cx)
+    });
+    cx.run_until_parked();
+}
+
+#[gpui::test]
+fn preview_and_back_still_take_typing_in_an_empty_document(cx: &mut TestAppContext) {
+    let (document, cx) = open("", MarkdownMode::Visual, cx);
+    focus(&document, cx);
+    cx.simulate_keystrokes("escape");
+    mode(&document, MarkdownMode::Preview, cx);
+    mode(&document, MarkdownMode::Visual, cx);
+    cx.simulate_input("Hi");
+    assert_eq!(text(&document, cx), "Hi");
+}
+
+#[gpui::test]
+fn undo_in_an_untouched_block_steps_the_document(cx: &mut TestAppContext) {
+    let (document, cx) = open("Seed", MarkdownMode::Source, cx);
+    document.update(cx, |document, cx| document.set_text("", cx));
+    mode(&document, MarkdownMode::Visual, cx);
+    cx.simulate_keystrokes("secondary-z");
+    cx.run_until_parked();
+    assert_eq!(text(&document, cx), "Seed", "the source edit is undone");
+    cx.simulate_keystrokes("secondary-shift-z");
+    cx.run_until_parked();
+    assert_eq!(text(&document, cx), "", "and redone");
+}
+
+#[gpui::test]
+fn undo_in_a_typed_block_stays_in_the_block(cx: &mut TestAppContext) {
+    let (document, cx) = open("Seed", MarkdownMode::Source, cx);
+    document.update(cx, |document, cx| document.set_text(TEXT, cx));
+    mode(&document, MarkdownMode::Visual, cx);
+    press(1, Modifiers::none(), cx);
+    cx.simulate_input(" x");
+    cx.simulate_keystrokes("secondary-z");
+    cx.run_until_parked();
+    assert_eq!(
+        text(&document, cx),
+        TEXT,
+        "the typing went, not the edit before"
+    );
+    assert_eq!(opened(&document, cx), "Blend toward white.", "still open");
+}
+
+#[gpui::test]
+fn redo_after_undo_stays_in_the_block(cx: &mut TestAppContext) {
+    let (document, cx) = open("", MarkdownMode::Visual, cx);
+    focus(&document, cx);
+    cx.simulate_input("Hi");
+    cx.simulate_keystrokes("secondary-z");
+    assert_eq!(text(&document, cx), "");
+    cx.simulate_keystrokes("secondary-shift-z");
+    assert_eq!(text(&document, cx), "Hi", "the block's own redo");
+    assert_eq!(opened(&document, cx), "Hi", "the block stays open");
+}
+
+#[gpui::test]
+fn redo_after_undo_in_a_written_block_stays_in_it(cx: &mut TestAppContext) {
+    let (document, cx) = open("Seed", MarkdownMode::Visual, cx);
+    press(0, Modifiers::none(), cx);
+    cx.simulate_input("!");
+    cx.simulate_keystrokes("secondary-z secondary-shift-z");
+    assert_eq!(text(&document, cx), "Seed!");
+    assert_eq!(opened(&document, cx), "Seed!", "the block stays open");
+}
+
+#[gpui::test]
+fn typing_lands_after_undo_empties_the_document(cx: &mut TestAppContext) {
+    let (document, cx) = open("", MarkdownMode::Visual, cx);
+    focus(&document, cx);
+    cx.simulate_input("Hi");
+    mode(&document, MarkdownMode::Source, cx);
+    mode(&document, MarkdownMode::Visual, cx);
+    cx.simulate_keystrokes("secondary-z");
+    cx.run_until_parked();
+    assert_eq!(text(&document, cx), "");
+    cx.simulate_input("Next");
+    assert_eq!(text(&document, cx), "Next");
+}

src/documents/document/tests/mod.rs

@@ -22,7 +22,7 @@ pub(super) fn open<'a>(
 }
 
 /// Presses block `ix` where it is drawn.
-fn press(ix: usize, modifiers: Modifiers, cx: &mut VisualTestContext) {
+pub(super) fn press(ix: usize, modifiers: Modifiers, cx: &mut VisualTestContext) {
     let bounds = cx
         .debug_bounds(Box::leak(format!("markdown-block-{ix}").into_boxed_str()))
         .expect("the block is drawn");
@@ -365,6 +365,7 @@ fn a_press_after_a_write_back_waits_for_the_long_read(cx: &mut TestAppContext) {
     assert_eq!(opened(&document, cx), "B", "once read, B opens whole");
 }
 
+mod history;
 mod place;
 
 #[gpui::test]
@@ -397,78 +398,3 @@ fn a_text_past_the_largest_read_is_never_read(cx: &mut TestAppContext) {
     });
     assert_eq!((blocks, outline), (0, 0), "the old read is gone");
 }
-
-/// Focus on `document`'s own handle, as an owner gives it.
-fn focus(document: &Entity<MarkdownDocument>, cx: &mut VisualTestContext) {
-    let handle = document.read_with(cx, |document, cx| {
-        gpui::Focusable::focus_handle(document, cx)
-    });
-    cx.update(|window, cx| window.focus(&handle, cx));
-    cx.run_until_parked();
-}
-
-#[gpui::test]
-fn an_empty_visual_document_takes_typing_on_focus(cx: &mut TestAppContext) {
-    let (document, cx) = open("", MarkdownMode::Visual, cx);
-    focus(&document, cx);
-    cx.simulate_input("Hi");
-    assert_eq!(text(&document, cx), "Hi", "typing lands with no press");
-    cx.simulate_keystrokes("escape");
-    cx.run_until_parked();
-    assert_eq!(text(&document, cx), "Hi", "escape keeps it");
-}
-
-#[gpui::test]
-fn focus_opens_no_block_in_a_written_document(cx: &mut TestAppContext) {
-    let (document, cx) = open(TEXT, MarkdownMode::Visual, cx);
-    focus(&document, cx);
-    cx.simulate_input("x");
-    assert_eq!(text(&document, cx), TEXT);
-}
-
-fn mode(document: &Entity<MarkdownDocument>, mode: MarkdownMode, cx: &mut VisualTestContext) {
-    document.update_in(cx, |document, window, cx| {
-        document.set_mode(mode, window, cx)
-    });
-    cx.run_until_parked();
-}
-
-#[gpui::test]
-fn preview_and_back_still_take_typing_in_an_empty_document(cx: &mut TestAppContext) {
-    let (document, cx) = open("", MarkdownMode::Visual, cx);
-    focus(&document, cx);
-    cx.simulate_keystrokes("escape");
-    mode(&document, MarkdownMode::Preview, cx);
-    mode(&document, MarkdownMode::Visual, cx);
-    cx.simulate_input("Hi");
-    assert_eq!(text(&document, cx), "Hi");
-}
-
-#[gpui::test]
-fn undo_in_an_untouched_block_steps_the_document(cx: &mut TestAppContext) {
-    let (document, cx) = open("Seed", MarkdownMode::Source, cx);
-    document.update(cx, |document, cx| document.set_text("", cx));
-    mode(&document, MarkdownMode::Visual, cx);
-    cx.simulate_keystrokes("secondary-z");
-    cx.run_until_parked();
-    assert_eq!(text(&document, cx), "Seed", "the source edit is undone");
-    cx.simulate_keystrokes("secondary-shift-z");
-    cx.run_until_parked();
-    assert_eq!(text(&document, cx), "", "and redone");
-}
-
-#[gpui::test]
-fn undo_in_a_typed_block_stays_in_the_block(cx: &mut TestAppContext) {
-    let (document, cx) = open("Seed", MarkdownMode::Source, cx);
-    document.update(cx, |document, cx| document.set_text(TEXT, cx));
-    mode(&document, MarkdownMode::Visual, cx);
-    press(1, Modifiers::none(), cx);
-    cx.simulate_input(" x");
-    cx.simulate_keystrokes("secondary-z");
-    cx.run_until_parked();
-    assert_eq!(
-        text(&document, cx),
-        TEXT,
-        "the typing went, not the edit before"
-    );
-}

src/documents/document/visual.rs

@@ -164,15 +164,15 @@ impl Render for MarkdownDocument {
                 .on_action(cx.listener(|document, _: &Redo, window, cx| {
                     document.history(true, window, cx);
                 }))
-                // An untouched block leaves undo to the document.
+                // Past the block's own history, the document's.
                 .capture_action(cx.listener(|document, _: &forms::Undo, window, cx| {
-                    if document.untouched(cx) {
+                    if document.at_edge_of_history(false, cx) {
                         cx.stop_propagation();
                         document.history(false, window, cx);
                     }
                 }))
                 .capture_action(cx.listener(|document, _: &forms::Redo, window, cx| {
-                    if document.untouched(cx) {
+                    if document.at_edge_of_history(true, cx) {
                         cx.stop_propagation();
                         document.history(true, window, cx);
                     }

src/forms/text/mod.rs

@@ -220,6 +220,14 @@ impl TextInput {
         &self.label
     }
 
+    /// A step left in that direction of its history.
+    pub(crate) fn can_step(&self, redo: bool) -> bool {
+        match redo {
+            true => self.history.can_redo(),
+            false => self.history.can_undo(),
+        }
+    }
+
     pub fn selection(&self) -> Range<usize> {
         self.selection.clone()
     }