change the way we calculate the newCursorIdx when we delete using the 'dk' motion while on the last line. We go to the buffer's last line and find the first column. This more directly expresses what we want and now passes the failing unit test for 'dk'.

fcore/normal-mode/make-normal-delete.sml

@@ -486,14 +486,6 @@ struct
       (* deleting from last line *)
       let
         (* go to first column of previous line *)
-        val buffer = LineGap.goToIdx (lineIdx, buffer)
-        val newCursorIdx = Cursor.viH (buffer, lineIdx, 1)
-        val buffer = LineGap.goToIdx (newCursorIdx, buffer)
-        val newCursorIdx = Cursor.vi0 (buffer, newCursorIdx)
-
-        (* clip endOfLine so we leave a newline at end of file *)
-        val endOfLine = Int.max (0, #textLength buffer - 1)
-
         val buffer = LineGap.goToIdx (endOfLine, buffer)
         val initialMsg = Fn.initMsgs (lineIdx, length, buffer)
         val buffer = LineGap.delete (lineIdx, length, buffer)
@@ -501,6 +493,19 @@ struct
         val buffer =
           if #textLength buffer = 0 then LineGap.append ("\n", buffer)
           else buffer
+
+        (* since we deleted from the last line,
+         * we want to place the cursor at the first column
+         * of the now-last line in the buffer. *)
+        val newCursorIdx = Int.max (#textLength buffer - 1, 0)
+        val buffer = LineGap.goToIdx (newCursorIdx, buffer)
+        val newCursorIdx =
+          if Cursor.isOnNewlineAfterChr (buffer, newCursorIdx) then
+            newCursorIdx - 1
+          else
+            newCursorIdx
+        val buffer = LineGap.goToIdx (newCursorIdx, buffer)
+        val newCursorIdx = Cursor.vi0 (buffer, newCursorIdx)
       in
         finishAfterDeletingBuffer (app, newCursorIdx, buffer, time, initialMsg)
       end

temp.txt

@@ -1,3 +1,5 @@
 hello
 world
 
+world
+hello