Replacing a selection with the register keeps its direction

R always left the head on the pasted text's last char. helix maps the
replaced range through the change, so a backward selection comes back
backward, its head on the first char: helix-golf's reverse_golf_example
(xbR) is where it showed. SPC R shares the path.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 21 insertions, 8 deletions

diff --git a/src/edit.zig b/src/edit.zig
index 56d537bf..fb8681d8 100644
--- a/src/edit.zig
+++ b/src/edit.zig
@@ -1125,27 +1125,40 @@ pub fn normalReplaceYank(p: *Pardes, t: *Text) void {
     replaceWithText(p, t, p.yank orelse return);
 }
 
-/// The pasted text becomes the selection, head on its last char (which for
-/// a trailing-newline `y` is the '\n' cell of the last full line).
+/// The pasted text becomes the selection, in the direction the replaced one
+/// had: a forward head lands on its last char (which for a trailing-newline
+/// `y` is the '\n' cell of the last full line), a backward one on its first.
 fn replaceWithText(p: *Pardes, t: *Text, y: []const u8) void {
     if (y.len == 0) return;
     t.select = false;
     const eb = editTextEol(p, t, selRows(t)) orelse return;
     const r = selRange(t, eb.text, eb.row0);
+    const back = t.vsel.active and (t.cur_row < t.vsel.row or (t.cur_row == t.vsel.row and t.cur_col < t.vsel.col));
     pushUndo(p, t);
     const new = modal.replaceRange(p.gpa, eb.text, r.a, r.b, y) catch return;
     setEditText(p, t, new);
     t.msel.active = false;
-    t.vsel = .{ .active = modal.nextGrapheme(y, 0) < y.len, .row = @as(i32, @intCast(r.a.row)) + eb.row0, .col = @intCast(r.a.col), .explicit = false };
     const end = modal.advanceBy(r.a, y);
+    var last_row: i32 = undefined;
+    var last_col: i32 = undefined;
     if (end.col > 0) {
-        t.cur_row = @as(i32, @intCast(end.row)) + eb.row0;
-        t.cur_col = @intCast(modal.prevGrapheme(modal.lineSlice(new, end.row), end.col));
+        last_row = @as(i32, @intCast(end.row)) + eb.row0;
+        last_col = @intCast(modal.prevGrapheme(modal.lineSlice(new, end.row), end.col));
     } else {
-        // the yank ended in '\n': the cursor lands ON that newline
-        t.cur_row = @as(i32, @intCast(end.row -| 1)) + eb.row0;
-        t.cur_col = @intCast(modal.lineSlice(new, end.row -| 1).len);
+        // the yank ended in '\n': its last cell is that newline
+        last_row = @as(i32, @intCast(end.row -| 1)) + eb.row0;
+        last_col = @intCast(modal.lineSlice(new, end.row -| 1).len);
     }
+    const first_row = @as(i32, @intCast(r.a.row)) + eb.row0;
+    const first_col: i32 = @intCast(r.a.col);
+    t.vsel = .{
+        .active = modal.nextGrapheme(y, 0) < y.len,
+        .row = if (back) last_row else first_row,
+        .col = if (back) last_col else first_col,
+        .explicit = false,
+    };
+    t.cur_row = if (back) first_row else last_row;
+    t.cur_col = if (back) first_col else last_col;
     t.cur_pinned = true;
     t.sticky_col = -1;
     t.show();