fix: handle checkbox rendering in single line nested lists

## Details

Issue: #659

We render custom checkboxes by tracking the row in which they appear on
and if that matches the start of a list item a checkbox is shown.

However this does not properly handle the ability to nest list items all
in one line, i.e. `- - - [-] triply nested custom checkbox`.

Currently if this happens all of the marker nodes end up hidden, which
is not the correct behavior. The fix is to add a check that the checkbox
node starts immediately after the list item's marker node. Since the
marker node absorbs additional space we don't need to do anything
special to handle different amounts of whitespace. This should make the
behavior between custom and regular checkboxes consistent as regular
checkboxes must be at the start of a list according to the parser.

Author: MeanderingProgrammer

CHANGELOG.md

@@ -11,6 +11,7 @@
   [3f3eea9](https://github.com/MeanderingProgrammer/render-markdown.nvim/commit/3f3eea97b80839f629c951ca660ffd125bfa5b34)
 - allow rendering when window is in diff mode [#645](https://github.com/MeanderingProgrammer/render-markdown.nvim/issues/645)
   [629eb95](https://github.com/MeanderingProgrammer/render-markdown.nvim/commit/629eb9533ec989d9d5c6cab8f3ad5372422c24e0)
+- add snacks.nvim image as conflict if latex is enabled [dcb7751](https://github.com/MeanderingProgrammer/render-markdown.nvim/commit/dcb77511efb1665b5073d8396a0033b3e4d680f6)
 
 ### Bug Fixes
 

doc/render-markdown.txt

@@ -1,5 +1,5 @@
 *render-markdown.txt*                       Improve viewing Markdown in Neovim
-                                  For NVIM v0.12.2    Last change: 2026 May 24
+                                  For NVIM v0.12.2    Last change: 2026 May 25
 
 ==============================================================================
 Table of Contents                          *render-markdown-table-of-contents*

lua/render-markdown/handler/latex.lua

@@ -195,7 +195,7 @@ function Handler:render(row, nodes)
                 local _, line = node:line('below', 1)
                 col = line and str.spaces('start', line) or 0
             else
-                local _, line = node:line('above', 0)
+                local _, line = node:line('first', 0)
                 col = self.context:width({
                     text = line and line:sub(1, node.start_col) or '',
                     start_row = node.start_row,

lua/render-markdown/health.lua

@@ -13,7 +13,7 @@ local state = require('render-markdown.state')
 local M = {}
 
 ---@private
-M.version = '8.12.16'
+M.version = '8.12.17'
 
 function M.check()
     M.start('versions')

lua/render-markdown/render/markdown/checkbox.lua

@@ -30,6 +30,9 @@ function Render:setup()
     if not value then
         return false
     end
+    if value.node.start_col ~= marker.end_col then
+        return false
+    end
     self.data = {
         marker = marker,
         checkbox = value.node,

tests/checkbox_spec.lua

@@ -0,0 +1,36 @@
+---@module 'luassert'
+
+local util = require('tests.util')
+
+describe('checkbox', function()
+    it('handle nested list items', function()
+        util.setup.text({
+            '1.  -  [x]  Checked Checkbox',
+            '1.  -  [-]  Todo Checkbox',
+        })
+        local marks = util.marks()
+        marks:add({ 0, 0 }, { 0, 4 }, util.ordered(1))
+        marks:add({ 0, 0 }, { 4, 7 }, util.conceal())
+        marks:add(0, 7, util.checkbox('checked', 1))
+        marks:add({ 0, 0 }, { 10, 11 }, util.conceal())
+        marks:add({ 1, 1 }, { 0, 4 }, util.ordered(2))
+        marks:add({ 1, 1 }, { 4, 7 }, util.conceal())
+        marks:add(1, 7, util.checkbox('todo', 0))
+        marks:add(1, 11, util.padding(1, false))
+        util.assert_view(marks, {
+            '1.  󰱒   Checked Checkbox',
+            '2.  󰥔   Todo Checkbox',
+        })
+    end)
+
+    it('ignores invalid position', function()
+        util.setup.text({
+            '- Todo [-] Checkbox',
+        })
+        local marks = util.marks()
+        marks:add({ 0, 0 }, { 0, 2 }, util.bullet(1))
+        util.assert_view(marks, {
+            '● Todo - Checkbox',
+        })
+    end)
+end)

tests/demo/box_dash_quote_spec.lua

@@ -13,26 +13,14 @@ describe('demo/box_dash_quote.md', function()
         marks:add(row:get(0, 1), { 0, 0 }, util.heading.bg(1))
 
         marks:add(row:get(1, 0), { 0, 2 }, util.conceal())
-        marks:add(row:get(0), 2, {
-            virt_text = { { '󰄱 ', 'RmUnchecked' }, { ' ', 'Normal' } },
-            virt_text_pos = 'overlay',
-        })
+        marks:add(row:get(0), 2, util.checkbox('unchecked', 1))
         marks:add(row:get(0, 0), { 5, 6 }, util.conceal())
         marks:add(row:get(1, 0), { 0, 2 }, util.conceal())
-        marks:add(row:get(0), 2, {
-            virt_text = { { '󰱒 ', 'RmChecked' }, { ' ', 'Normal' } },
-            virt_text_pos = 'overlay',
-        })
+        marks:add(row:get(0), 2, util.checkbox('checked', 1))
         marks:add(row:get(0, 0), { 5, 6 }, util.conceal())
         marks:add(row:get(1, 0), { 0, 2 }, util.conceal())
-        marks:add(row:get(0), 2, {
-            virt_text = { { '󰥔 ', 'RmTodo' } },
-            virt_text_pos = 'overlay',
-        })
-        marks:add(row:get(0), 6, {
-            virt_text = { { ' ', 'Normal' } },
-            virt_text_pos = 'inline',
-        })
+        marks:add(row:get(0), 2, util.checkbox('todo', 0))
+        marks:add(row:get(0), 6, util.padding(1, false))
         marks:add(row:get(1, 0), { 0, 2 }, util.bullet(1))
 
         marks:add(row:get(2), 0, {

tests/util.lua

@@ -98,6 +98,28 @@ function M.highlight(kind)
     }
 end
 
+---@param kind 'checked'|'unchecked'|'todo'
+---@param space integer
+---@return vim.api.keyset.set_extmark
+function M.checkbox(kind, space)
+    local line = {} ---@type render.md.mark.Line
+    if kind == 'checked' then
+        line[#line + 1] = { '󰱒 ', 'RmChecked' }
+    elseif kind == 'unchecked' then
+        line[#line + 1] = { '󰄱 ', 'RmUnchecked' }
+    elseif kind == 'todo' then
+        line[#line + 1] = { '󰥔 ', 'RmTodo' }
+    end
+    if space > 0 then
+        line[#line + 1] = { (' '):rep(space), 'Normal' }
+    end
+    ---@type vim.api.keyset.set_extmark
+    return {
+        virt_text = line,
+        virt_text_pos = 'overlay',
+    }
+end
+
 ---@param level integer
 ---@param spaces? integer
 ---@return vim.api.keyset.set_extmark
@@ -155,13 +177,13 @@ function M.quote(highlight)
 end
 
 ---@param spaces integer
----@param priority? integer
+---@param priority? integer|false
 ---@param highlight? string
 ---@return vim.api.keyset.set_extmark
 function M.padding(spaces, priority, highlight)
     ---@type vim.api.keyset.set_extmark
     return {
-        priority = priority or 100,
+        priority = priority or (priority ~= false and 100 or nil),
         virt_text = { { (' '):rep(spaces), highlight or 'Normal' } },
         virt_text_pos = 'inline',
     }