feat: add <C-a> / <C-x> keymaps for priority increment/decrement

Problem: Priority could only be cycled with `g!` (0→1→2→3→0), with no
way to directly increment or decrement.

Solution: Add `adjust_priority()` with clamping at 0 and `max_priority`,
exposed as `increment_priority()` / `decrement_priority()` on `<C-a>` /
`<C-x>`. Includes `<Plug>` mappings and vimdoc.

doc/pending.txt

@@ -299,6 +299,8 @@ Default buffer-local keys: ~
     `gz`          Undo the last `:w` save (`undo`)
     `o`           Insert a new task line below (`open_line`)
     `O`           Insert a new task line above (`open_line_above`)
+    `<C-a>`       Increment priority (clamped at `max_priority`) (`priority_up`)
+    `<C-x>`       Decrement priority (clamped at 0) (`priority_down`)
     `J`           Move task down within its category (`move_down`)
     `K`           Move task up within its category (`move_up`)
     `zc`          Fold the current category section (requires `folding`)
@@ -413,6 +415,16 @@ old keys to `false`: >lua
     Toggle blocked status for the task under the cursor.
     If the task is already `blocked`, reverts to `pending`.
 
+                                                *<Plug>(pending-priority-up)*
+<Plug>(pending-priority-up)
+    Increment the priority level for the task under the cursor, clamped
+    at `max_priority`. Default key: `<C-a>`.
+
+                                              *<Plug>(pending-priority-down)*
+<Plug>(pending-priority-down)
+    Decrement the priority level for the task under the cursor, clamped
+    at 0. Default key: `<C-x>`.
+
                                                    *<Plug>(pending-open-line)*
 <Plug>(pending-open-line)
     Insert a correctly-formatted blank task line below the cursor.

lua/pending/config.lua

@@ -137,6 +137,8 @@ local defaults = {
     move_up = 'K',
     wip = 'gw',
     blocked = 'gb',
+    priority_up = '<C-a>',
+    priority_down = '<C-x>',
   },
   sync = {},
   icons = {

lua/pending/init.lua

@@ -363,6 +363,12 @@ function M._setup_buf_mappings(bufnr)
     blocked = function()
       M.toggle_status('blocked')
     end,
+    priority_up = function()
+      M.increment_priority()
+    end,
+    priority_down = function()
+      M.decrement_priority()
+    end,
     undo = function()
       M.undo_write()
     end,
@@ -646,6 +652,56 @@ function M.toggle_priority()
   end
 end
 
+---@param delta integer
+---@return nil
+local function adjust_priority(delta)
+  local bufnr = buffer.bufnr()
+  if not bufnr then
+    return
+  end
+  if not require_saved() then
+    return
+  end
+  local row = vim.api.nvim_win_get_cursor(0)[1]
+  local meta = buffer.meta()
+  if not meta[row] or meta[row].type ~= 'task' then
+    return
+  end
+  local id = meta[row].id
+  if not id then
+    return
+  end
+  local s = get_store()
+  local task = s:get(id)
+  if not task then
+    return
+  end
+  local max = require('pending.config').get().max_priority or 3
+  local new_priority = math.max(0, math.min(max, task.priority + delta))
+  if new_priority == task.priority then
+    return
+  end
+  s:update(id, { priority = new_priority })
+  _save_and_notify()
+  buffer.render(bufnr)
+  for lnum, m in ipairs(buffer.meta()) do
+    if m.id == id then
+      vim.api.nvim_win_set_cursor(0, { lnum, 0 })
+      break
+    end
+  end
+end
+
+---@return nil
+function M.increment_priority()
+  adjust_priority(1)
+end
+
+---@return nil
+function M.decrement_priority()
+  adjust_priority(-1)
+end
+
 ---@return nil
 function M.prompt_date()
   local bufnr = buffer.bufnr()

plugin/pending.lua

@@ -328,6 +328,14 @@ vim.keymap.set('n', '<Plug>(pending-blocked)', function()
   require('pending').toggle_status('blocked')
 end)
 
+vim.keymap.set('n', '<Plug>(pending-priority-up)', function()
+  require('pending').increment_priority()
+end)
+
+vim.keymap.set('n', '<Plug>(pending-priority-down)', function()
+  require('pending').decrement_priority()
+end)
+
 vim.keymap.set('n', '<Plug>(pending-filter)', function()
   vim.ui.input({ prompt = 'Filter: ' }, function(input)
     if input then