fix: keep line after deleting empty bullet (#27)

# Motivation

Pressing Return on an empty bullet with `delete_last_bullet_if_empty`
enabled removed the whole line, moving the cursor up. The spec now
requires the bullet marker to be cleared while keeping the cursor on
that line.

# Summary of Changes

- Route whitespace-only bullet text through the shared empty-bullet
handling.
- Remove the special-case insert-mode deletion path that used `ddi`.
- Update `LC-003` coverage and spec text to assert that the blank line
remains.

# Testing

- `mise run test:spec LC-003`
- `mise run test:spec LC-004`
- `mise run test:spec LC-005`
- `mise run openspec:check`
- `mise run test`
- `mise run fmt:check`

# Dependencies/Special Considerations

none

Author: dkarter

lua/bullets/actions.lua

@@ -377,7 +377,7 @@ local function checkbox_continuation_prefix(bullet, prefix)
 end
 
 local function is_empty_bullet_text(text)
-  if text == '' then
+  if text:match '^%s*$' then
     return true
   end
 
@@ -908,17 +908,6 @@ function M.insert_new_bullet()
     return ''
   end
 
-  if bullet.text:match '^%s*$' and config.options.delete_last_bullet_if_empty == 1 then
-    if mode ~= 'n' then
-      vim.api.nvim_feedkeys(keys '<Esc>ddi', 'n', false)
-      return ''
-    end
-
-    vim.api.nvim_buf_set_lines(0, lnum - 1, lnum, false, {})
-    vim.cmd.startinsert()
-    return ''
-  end
-
   if is_empty_bullet_text(bullet.text) and delete_empty_bullet(lnum, bullet, mode) then
     return ''
   end

openspec/specs/list-continuation/spec.md

@@ -39,6 +39,7 @@ The plugin SHALL handle an empty continued list item according to `delete_last_b
 - AND the current line is an empty list item
 - WHEN bullet insertion is triggered
 - THEN the empty list item is removed
+- AND the cursor remains on the same line
 
 #### Scenario: Promote empty item {#LC-004}
 

test/bullets_spec.lua

@@ -220,17 +220,16 @@ describe('Bullets.vim', function()
         helpers.new_buffer {
           '# Hello there',
           '- this is the first bullet',
+          '- ',
         }
-        -- First CR creates "- " empty bullet, second CR on empty bullet deletes it
-        helpers.feedkeys 'A<CR><CR>'
+        -- CR on empty bullet deletes it
+        helpers.feedkeys 'A<CR>'
         local lines = helpers.get_lines()
-        -- Strip trailing empty lines before comparison.
-        while #lines > 0 and lines[#lines] == '' do
-          table.remove(lines)
-        end
+
         assert.are.same({
           '# Hello there',
           '- this is the first bullet',
+          '', -- cursor should be here, we do not want to remove the line
         }, lines)
       end)