From d243d5897a76052582694c3581607ab898298bd9 Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Tue, 24 Feb 2026 23:14:53 -0500
Subject: [PATCH] refactor(buffer): update syntax, extmarks, and render for
 checkbox format

Problem: syntax patterns matched the old indent/[N] format; right_align
virtual text produced a broken layout in narrow windows; the done
strikethrough skipped past the '  ' indent leaving '- [x] ' unstyled;
render() added undo history entries so 'u' could undo a re-render.

Solution: update taskHeader/taskLine patterns for '## '/'- [.]'; rename
taskPriority -> taskCheckbox matching '[!]'; switch virt_text_pos to
'eol'; drop the +2 col_start offset so strikethrough covers '- [x] ';
guard nvim_buf_set_lines with undolevels=-1 so renders are not undoable.
Also fix open_line to insert '- [ ] ' and position cursor at col 6.
---
 lua/pending/buffer.lua | 19 +++++++++++--------
 syntax/pending.vim     |  8 ++++----
 2 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/lua/pending/buffer.lua b/lua/pending/buffer.lua
index 2036357..b60d633 100644
--- a/lua/pending/buffer.lua
+++ b/lua/pending/buffer.lua
@@ -56,9 +56,9 @@ local function setup_syntax(bufnr)
     vim.cmd([[
       syntax clear
       syntax match taskId /^\/\d\+\// conceal
-      syntax match taskHeader /^\S.*$/ contains=taskId
-      syntax match taskPriority /\[\d\+\] / contained containedin=taskLine
-      syntax match taskLine /^\/\d\+\/  .*$/ contains=taskId,taskPriority
+      syntax match taskHeader /^## .*$/ contains=taskId
+      syntax match taskCheckbox /\[!\]/ contained containedin=taskLine
+      syntax match taskLine /^\/\d\+\/- \[.\] .*$/ contains=taskId,taskCheckbox
     ]])
   end)
 end
@@ -72,8 +72,8 @@ function M.open_line(above)
   local row = vim.api.nvim_win_get_cursor(0)[1]
   local insert_row = above and (row - 1) or row
   vim.bo[bufnr].modifiable = true
-  vim.api.nvim_buf_set_lines(bufnr, insert_row, insert_row, false, { '  ' })
-  vim.api.nvim_win_set_cursor(0, { insert_row + 1, 2 })
+  vim.api.nvim_buf_set_lines(bufnr, insert_row, insert_row, false, { '- [ ] ' })
+  vim.api.nvim_win_set_cursor(0, { insert_row + 1, 6 })
   vim.cmd('startinsert!')
 end
 
@@ -113,18 +113,18 @@ local function apply_extmarks(bufnr, line_meta)
         if virt_text then
           vim.api.nvim_buf_set_extmark(bufnr, task_ns, row, 0, {
             virt_text = virt_text,
-            virt_text_pos = 'right_align',
+            virt_text_pos = 'eol',
           })
         end
       elseif m.due then
         vim.api.nvim_buf_set_extmark(bufnr, task_ns, row, 0, {
           virt_text = { { m.due, due_hl } },
-          virt_text_pos = 'right_align',
+          virt_text_pos = 'eol',
         })
       end
       if m.status == 'done' then
         local line = vim.api.nvim_buf_get_lines(bufnr, row, row + 1, false)[1] or ''
-        local col_start = line:find('/%d+/') and select(2, line:find('/%d+/')) + 2 or 0
+        local col_start = line:find('/%d+/') and select(2, line:find('/%d+/')) or 0
         vim.api.nvim_buf_set_extmark(bufnr, task_ns, row, col_start, {
           end_col = #line,
           hl_group = 'PendingDone',
@@ -168,8 +168,11 @@ function M.render(bufnr)
   _meta = line_meta
 
   vim.bo[bufnr].modifiable = true
+  local saved = vim.bo[bufnr].undolevels
+  vim.bo[bufnr].undolevels = -1
   vim.api.nvim_buf_set_lines(bufnr, 0, -1, false, lines)
   vim.bo[bufnr].modified = false
+  vim.bo[bufnr].undolevels = saved
 
   setup_syntax(bufnr)
   apply_extmarks(bufnr, line_meta)
diff --git a/syntax/pending.vim b/syntax/pending.vim
index b5f3da1..a8a0258 100644
--- a/syntax/pending.vim
+++ b/syntax/pending.vim
@@ -3,12 +3,12 @@ if exists('b:current_syntax')
 endif
 
 syntax match taskId /^\/\d\+\// conceal
-syntax match taskHeader /^\S.*$/ contains=taskId
-syntax match taskPriority /!\ze / contained
-syntax match taskLine /^\/\d\+\/  .*$/ contains=taskId,taskPriority
+syntax match taskHeader /^## .*$/ contains=taskId
+syntax match taskCheckbox /\[!\]/ contained containedin=taskLine
+syntax match taskLine /^\/\d\+\/- \[.\] .*$/ contains=taskId,taskCheckbox
 
 highlight default link taskHeader PendingHeader
-highlight default link taskPriority PendingPriority
+highlight default link taskCheckbox PendingPriority
 highlight default link taskLine Normal
 
 let b:current_syntax = 'task'