feat(buffer): open as bottom-drawer split like fugitive (#23)

* feat(buffer): open as bottom-drawer split like fugitive

Problem: :Pending replaced the current buffer, making it impossible to
view tasks alongside the file being edited. No way to close the drawer
without :q or switching buffers manually.

Solution: open the task buffer in a botright horizontal split instead of
replacing the current buffer. Track the drawer window ID so re-opening
focuses it rather than creating a second split. Set winfixheight so the
drawer keeps its height when other windows open or close. Add q/<Esc>
mappings to close the drawer, and a WinClosed autocmd to clear the
tracked window ID when the user closes it manually. Add drawer_height
config option (default 15).

* fix(buffer): default to natural split height like fugitive

Problem: hardcoded drawer_height=15 was too small and diverged from
fugitive's model. Fugitive issues a plain botright split and lets Vim's
own split rules (equalalways, winheight) divide the available space.

Solution: remove the default height so the split sizes naturally. Only
call nvim_win_set_height when the user sets drawer_height to a positive
value, preserving the opt-in customization path.

lua/pending/buffer.lua

@@ -7,6 +7,8 @@ local M = {}
 
 ---@type integer?
 local task_bufnr = nil
+---@type integer?
+local task_winid = nil
 local task_ns = vim.api.nvim_create_namespace('pending')
 ---@type 'category'|'priority'|nil
 local current_view = nil
@@ -25,11 +27,27 @@ function M.bufnr()
   return task_bufnr
 end
 
+---@return integer?
+function M.winid()
+  return task_winid
+end
+
 ---@return string?
 function M.current_view_name()
   return current_view
 end
 
+function M.clear_winid()
+  task_winid = nil
+end
+
+function M.close()
+  if task_winid and vim.api.nvim_win_is_valid(task_winid) then
+    vim.api.nvim_win_close(task_winid, false)
+  end
+  task_winid = nil
+end
+
 ---@param bufnr integer
 local function set_buf_options(bufnr)
   vim.bo[bufnr].buftype = 'acwrite'
@@ -50,6 +68,7 @@ local function set_win_options(winid)
   vim.wo[winid].foldcolumn = '0'
   vim.wo[winid].spell = false
   vim.wo[winid].cursorline = true
+  vim.wo[winid].winfixheight = true
 end
 
 ---@param bufnr integer
@@ -251,24 +270,25 @@ function M.open()
   setup_highlights()
   store.load()
 
-  if task_bufnr and vim.api.nvim_buf_is_valid(task_bufnr) then
-    local wins = vim.fn.win_findbuf(task_bufnr)
-    if #wins > 0 then
-      vim.api.nvim_set_current_win(wins[1])
-      M.render(task_bufnr)
-      return task_bufnr
-    end
-    vim.api.nvim_set_current_buf(task_bufnr)
-    set_win_options(vim.api.nvim_get_current_win())
+  if task_winid and vim.api.nvim_win_is_valid(task_winid) then
+    vim.api.nvim_set_current_win(task_winid)
     M.render(task_bufnr)
-    return task_bufnr
+    return task_bufnr --[[@as integer]]
   end
 
-  task_bufnr = vim.api.nvim_create_buf(true, false)
+  if not (task_bufnr and vim.api.nvim_buf_is_valid(task_bufnr)) then
+    task_bufnr = vim.api.nvim_create_buf(true, false)
+    set_buf_options(task_bufnr)
+  end
 
-  set_buf_options(task_bufnr)
-  vim.api.nvim_set_current_buf(task_bufnr)
-  set_win_options(vim.api.nvim_get_current_win())
+  vim.cmd('botright new')
+  task_winid = vim.api.nvim_get_current_win()
+  vim.api.nvim_win_set_buf(task_winid, task_bufnr)
+  local h = config.get().drawer_height
+  if h and h > 0 then
+    vim.api.nvim_win_set_height(task_winid, h)
+  end
+  set_win_options(task_winid)
 
   M.render(task_bufnr)
 

lua/pending/config.lua

@@ -9,6 +9,7 @@
 ---@field date_format string
 ---@field date_syntax string
 ---@field category_order? string[]
+---@field drawer_height? integer
 ---@field gcal? pending.GcalConfig
 
 ---@class pending.config

lua/pending/init.lua

@@ -38,11 +38,25 @@ function M._setup_autocmds(bufnr)
       end
     end,
   })
+  vim.api.nvim_create_autocmd('WinClosed', {
+    group = group,
+    callback = function(ev)
+      if tonumber(ev.match) == buffer.winid() then
+        buffer.clear_winid()
+      end
+    end,
+  })
 end
 
 ---@param bufnr integer
 function M._setup_buf_mappings(bufnr)
   local opts = { buffer = bufnr, silent = true }
+  vim.keymap.set('n', 'q', function()
+    buffer.close()
+  end, opts)
+  vim.keymap.set('n', '<Esc>', function()
+    buffer.close()
+  end, opts)
   vim.keymap.set('n', '<CR>', function()
     M.toggle_complete()
   end, opts)