feat(buffer): add configurable eol_format for EOL virtual text

Problem: EOL virtual text order (category → recurrence → due) and the
double-space separator are hardcoded in `apply_extmarks()`. Users cannot
reorder, omit, or restyle metadata fields.

Solution: Add `eol_format` config field (default `'%c  %r  %d'`) with
`%c`, `%r`, `%d` specifiers. `parse_eol_format()` tokenizes the format
string; `build_eol_virt()` resolves specifiers against `LineMeta` and
collapses literals around absent fields.

doc/pending.txt

@@ -648,6 +648,32 @@ Fields: ~
                          virtual text in the buffer. Examples: `'%Y-%m-%d'`
                          for ISO dates, `'%d %b'` for day-first.
 
+    {eol_format}         (string, default: '%c  %r  %d')
+                         Format string controlling the order, content, and
+                         separators of end-of-line virtual text on task lines.
+                         Three specifiers are available:
+
+                           `%c`  category icon + name (`PendingHeader`)
+                           `%r`  recurrence icon + pattern (`PendingRecur`)
+                           `%d`  due icon + date (`PendingDue` / `PendingOverdue`)
+
+                         Literal text between specifiers is rendered with the
+                         `Normal` highlight group and acts as a separator.
+                         When a specifier's data is absent (e.g. `%d` on a
+                         task with no due date), the specifier and any
+                         surrounding literal text up to the next specifier
+                         are omitted — missing fields never leave gaps.
+
+                         `%c` only renders in priority view (where
+                         `show_category` is true). In category view it is
+                         always omitted regardless of the format string.
+
+                         Examples: >lua
+                             vim.g.pending = { eol_format = '%d  %r' }
+                             vim.g.pending = { eol_format = '%d | %r' }
+                             vim.g.pending = { eol_format = '%c  %d  %r' }
+<
+
     {input_date_formats} (string[], default: {})         *pending-input-formats*
                          List of strftime-like format strings tried in order
                          when parsing a `due:` token that does not match the

lua/pending/buffer.lua

@@ -12,7 +12,8 @@ local _store = nil
 local task_bufnr = nil
 ---@type integer?
 local task_winid = nil
-local task_ns = vim.api.nvim_create_namespace('pending')
+local ns_eol = vim.api.nvim_create_namespace('pending_eol')
+local ns_inline = vim.api.nvim_create_namespace('pending_inline')
 ---@type 'category'|'priority'|nil
 local current_view = nil
 ---@type pending.LineMeta[]
@@ -25,6 +26,12 @@ local _initial_fold_loaded = false
 local _filter_predicates = {}
 ---@type table<integer, true>
 local _hidden_ids = {}
+---@type table<integer, true>
+local _dirty_rows = {}
+---@type boolean
+local _on_bytes_active = false
+---@type boolean
+local _rendering = false
 
 ---@return pending.LineMeta[]
 function M.meta()
@@ -89,7 +96,127 @@ end
 ---@param b? integer
 ---@return nil
 function M.clear_marks(b)
-  vim.api.nvim_buf_clear_namespace(b or task_bufnr, task_ns, 0, -1)
+  local bufnr = b or task_bufnr
+  vim.api.nvim_buf_clear_namespace(bufnr, ns_eol, 0, -1)
+  vim.api.nvim_buf_clear_namespace(bufnr, ns_inline, 0, -1)
+end
+
+---@param b integer
+---@param row integer
+---@return nil
+function M.clear_inline_row(b, row)
+  vim.api.nvim_buf_clear_namespace(b, ns_inline, row - 1, row)
+end
+
+---@return table<integer, true>
+function M.dirty_rows()
+  return _dirty_rows
+end
+
+---@return nil
+function M.clear_dirty_rows()
+  _dirty_rows = {}
+end
+
+---@param bufnr integer
+---@param row integer
+---@param m pending.LineMeta
+---@param icons table
+local function apply_inline_row(bufnr, row, m, icons)
+  if m.type == 'filter' then
+    local line = vim.api.nvim_buf_get_lines(bufnr, row, row + 1, false)[1] or ''
+    vim.api.nvim_buf_set_extmark(bufnr, ns_inline, row, 0, {
+      end_col = #line,
+      hl_group = 'PendingFilter',
+    })
+  elseif m.type == 'task' then
+    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+/')) or 0
+      vim.api.nvim_buf_set_extmark(bufnr, ns_inline, row, col_start, {
+        end_col = #line,
+        hl_group = 'PendingDone',
+      })
+    end
+    local line = vim.api.nvim_buf_get_lines(bufnr, row, row + 1, false)[1] or ''
+    local bracket_col = (line:find('%[') or 1) - 1
+    local icon, icon_hl
+    if m.status == 'done' then
+      icon, icon_hl = icons.done, 'PendingDone'
+    elseif m.priority and m.priority > 0 then
+      icon, icon_hl = icons.priority, 'PendingPriority'
+    else
+      icon, icon_hl = icons.pending, 'Normal'
+    end
+    vim.api.nvim_buf_set_extmark(bufnr, ns_inline, row, bracket_col, {
+      virt_text = { { '[' .. icon .. ']', icon_hl } },
+      virt_text_pos = 'overlay',
+      priority = 100,
+    })
+  elseif m.type == 'header' then
+    local line = vim.api.nvim_buf_get_lines(bufnr, row, row + 1, false)[1] or ''
+    vim.api.nvim_buf_set_extmark(bufnr, ns_inline, row, 0, {
+      end_col = #line,
+      hl_group = 'PendingHeader',
+    })
+    vim.api.nvim_buf_set_extmark(bufnr, ns_inline, row, 0, {
+      virt_text = { { icons.category .. ' ', 'PendingHeader' } },
+      virt_text_pos = 'overlay',
+      priority = 100,
+    })
+  end
+end
+
+---@param bufnr integer
+---@return nil
+function M.reapply_dirty_inline(bufnr)
+  if not next(_dirty_rows) then
+    return
+  end
+  local icons = config.get().icons
+  for row in pairs(_dirty_rows) do
+    local m = _meta[row]
+    if m then
+      vim.api.nvim_buf_clear_namespace(bufnr, ns_inline, row - 1, row)
+      apply_inline_row(bufnr, row - 1, m, icons)
+    end
+  end
+  _dirty_rows = {}
+end
+
+---@param bufnr integer
+---@return nil
+function M.attach_bytes(bufnr)
+  if _on_bytes_active then
+    return
+  end
+  _on_bytes_active = true
+  vim.api.nvim_buf_attach(bufnr, false, {
+    on_bytes = function(_, buf, _, start_row, _, _, old_end_row, _, _, new_end_row, _, _)
+      if buf ~= task_bufnr then
+        _on_bytes_active = false
+        return true
+      end
+      if _rendering then
+        return
+      end
+      local delta = new_end_row - old_end_row
+      if delta > 0 then
+        for _ = 1, delta do
+          table.insert(_meta, start_row + 2, { type = 'task' })
+        end
+      elseif delta < 0 then
+        for _ = 1, -delta do
+          if _meta[start_row + 2] then
+            table.remove(_meta, start_row + 2)
+          end
+        end
+      end
+      for r = start_row + 1, start_row + 1 + math.max(0, new_end_row) do
+        _dirty_rows[r] = true
+      end
+    end,
+  })
 end
 
 ---@return nil
@@ -205,7 +332,6 @@ function M.open_line(above)
   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, { '- [ ] ' })
-  table.insert(_meta, insert_row + 1, { type = 'task' })
   vim.api.nvim_win_set_cursor(0, { insert_row + 1, 6 })
   vim.cmd('startinsert!')
 end
@@ -226,75 +352,110 @@ function M.get_fold()
   end
 end
 
+---@class pending.EolSegment
+---@field type 'specifier'|'literal'
+---@field key? 'c'|'r'|'d'
+---@field text? string
+
+---@param fmt string
+---@return pending.EolSegment[]
+local function parse_eol_format(fmt)
+  local segments = {}
+  local pos = 1
+  local len = #fmt
+  while pos <= len do
+    if fmt:sub(pos, pos) == '%' and pos + 1 <= len then
+      local key = fmt:sub(pos + 1, pos + 1)
+      if key == 'c' or key == 'r' or key == 'd' then
+        table.insert(segments, { type = 'specifier', key = key })
+        pos = pos + 2
+      else
+        table.insert(segments, { type = 'literal', text = '%' .. key })
+        pos = pos + 2
+      end
+    else
+      local next_pct = fmt:find('%%', pos + 1)
+      local chunk = next_pct and fmt:sub(pos, next_pct - 1) or fmt:sub(pos)
+      table.insert(segments, { type = 'literal', text = chunk })
+      pos = pos + #chunk
+    end
+  end
+  return segments
+end
+
+---@param segments pending.EolSegment[]
+---@param m pending.LineMeta
+---@param icons pending.Icons
+---@return string[][]
+local function build_eol_virt(segments, m, icons)
+  local due_hl = m.overdue and 'PendingOverdue' or 'PendingDue'
+  local resolved = {}
+  for i, seg in ipairs(segments) do
+    if seg.type == 'specifier' then
+      local text, hl
+      if seg.key == 'c' and m.show_category and m.category then
+        text = icons.category .. ' ' .. m.category
+        hl = 'PendingHeader'
+      elseif seg.key == 'r' and m.recur then
+        text = icons.recur .. ' ' .. m.recur
+        hl = 'PendingRecur'
+      elseif seg.key == 'd' and m.due then
+        text = icons.due .. ' ' .. m.due
+        hl = due_hl
+      end
+      resolved[i] = text and { text = text, hl = hl, present = true }
+        or { present = false }
+    else
+      resolved[i] = { text = seg.text, hl = 'Normal', literal = true }
+    end
+  end
+
+  local virt_parts = {}
+  for i, r in ipairs(resolved) do
+    if r.literal then
+      local prev_present, next_present = false, false
+      for j = i - 1, 1, -1 do
+        if not resolved[j].literal then
+          prev_present = resolved[j].present
+          break
+        end
+      end
+      for j = i + 1, #resolved do
+        if not resolved[j].literal then
+          next_present = resolved[j].present
+          break
+        end
+      end
+      if prev_present and next_present then
+        table.insert(virt_parts, { r.text, r.hl })
+      end
+    elseif r.present then
+      table.insert(virt_parts, { r.text, r.hl })
+    end
+  end
+  return virt_parts
+end
+
 ---@param bufnr integer
 ---@param line_meta pending.LineMeta[]
 local function apply_extmarks(bufnr, line_meta)
-  local icons = config.get().icons
-  vim.api.nvim_buf_clear_namespace(bufnr, task_ns, 0, -1)
+  local cfg = config.get()
+  local icons = cfg.icons
+  local eol_segments = parse_eol_format(cfg.eol_format or '%c  %r  %d')
+  vim.api.nvim_buf_clear_namespace(bufnr, ns_eol, 0, -1)
+  vim.api.nvim_buf_clear_namespace(bufnr, ns_inline, 0, -1)
   for i, m in ipairs(line_meta) do
     local row = i - 1
-    if m.type == 'filter' then
-      local line = vim.api.nvim_buf_get_lines(bufnr, row, row + 1, false)[1] or ''
-      vim.api.nvim_buf_set_extmark(bufnr, task_ns, row, 0, {
-        end_col = #line,
-        hl_group = 'PendingFilter',
-      })
-    elseif m.type == 'task' then
-      local due_hl = m.overdue and 'PendingOverdue' or 'PendingDue'
-      local virt_parts = {}
-      if m.show_category and m.category then
-        table.insert(virt_parts, { icons.category .. ' ' .. m.category, 'PendingHeader' })
-      end
-      if m.recur then
-        table.insert(virt_parts, { icons.recur .. ' ' .. m.recur, 'PendingRecur' })
-      end
-      if m.due then
-        table.insert(virt_parts, { icons.due .. ' ' .. m.due, due_hl })
-      end
+    if m.type == 'task' then
+      local virt_parts = build_eol_virt(eol_segments, m, icons)
       if #virt_parts > 0 then
-        for p = 1, #virt_parts - 1 do
-          virt_parts[p][1] = virt_parts[p][1] .. '  '
-        end
-        vim.api.nvim_buf_set_extmark(bufnr, task_ns, row, 0, {
+        vim.api.nvim_buf_set_extmark(bufnr, ns_eol, row, 0, {
           virt_text = virt_parts,
           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+/')) or 0
-        vim.api.nvim_buf_set_extmark(bufnr, task_ns, row, col_start, {
-          end_col = #line,
-          hl_group = 'PendingDone',
-        })
-      end
-      local line = vim.api.nvim_buf_get_lines(bufnr, row, row + 1, false)[1] or ''
-      local bracket_col = (line:find('%[') or 1) - 1
-      local icon, icon_hl
-      if m.status == 'done' then
-        icon, icon_hl = icons.done, 'PendingDone'
-      elseif m.priority and m.priority > 0 then
-        icon, icon_hl = icons.priority, 'PendingPriority'
-      else
-        icon, icon_hl = icons.pending, 'Normal'
-      end
-      vim.api.nvim_buf_set_extmark(bufnr, task_ns, row, bracket_col, {
-        virt_text = { { '[' .. icon .. ']', icon_hl } },
-        virt_text_pos = 'overlay',
-        priority = 100,
-      })
-    elseif m.type == 'header' then
-      local line = vim.api.nvim_buf_get_lines(bufnr, row, row + 1, false)[1] or ''
-      vim.api.nvim_buf_set_extmark(bufnr, task_ns, row, 0, {
-        end_col = #line,
-        hl_group = 'PendingHeader',
-      })
-      vim.api.nvim_buf_set_extmark(bufnr, task_ns, row, 0, {
-        virt_text = { { icons.category .. ' ', 'PendingHeader' } },
-        virt_text_pos = 'overlay',
-        priority = 100,
-      })
     end
+    apply_inline_row(bufnr, row, m, icons)
   end
 end
 
@@ -448,12 +609,15 @@ function M.render(bufnr)
   end
 
   _meta = line_meta
+  _dirty_rows = {}
 
   snapshot_folds(bufnr)
   vim.bo[bufnr].modifiable = true
   local saved = vim.bo[bufnr].undolevels
   vim.bo[bufnr].undolevels = -1
+  _rendering = true
   vim.api.nvim_buf_set_lines(bufnr, 0, -1, false, lines)
+  _rendering = false
   vim.bo[bufnr].modified = false
   vim.bo[bufnr].undolevels = saved
 
@@ -507,6 +671,7 @@ function M.open()
   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)
+    M.attach_bytes(task_bufnr)
   end
 
   vim.cmd('botright new')

lua/pending/config.lua

@@ -64,6 +64,7 @@
 ---@field keymaps pending.Keymaps
 ---@field folding? boolean|pending.FoldingConfig
 ---@field sync? pending.SyncConfig
+---@field eol_format? string
 ---@field icons pending.Icons
 
 ---@class pending.config
@@ -78,6 +79,7 @@ local defaults = {
   date_syntax = 'due',
   recur_syntax = 'rec',
   someday_date = '9999-12-30',
+  eol_format = '%c  %r  %d',
   folding = true,
   category_order = {},
   keymaps = {

lua/pending/init.lua

@@ -251,12 +251,34 @@ function M._setup_autocmds(bufnr)
       end
     end,
   })
-  vim.api.nvim_create_autocmd({ 'TextChanged', 'TextChangedI' }, {
+  vim.api.nvim_create_autocmd('TextChangedI', {
+    group = group,
+    buffer = bufnr,
+    callback = function()
+      if not vim.bo[bufnr].modified then
+        return
+      end
+      for row in pairs(buffer.dirty_rows()) do
+        buffer.clear_inline_row(bufnr, row)
+      end
+    end,
+  })
+  vim.api.nvim_create_autocmd('TextChanged', {
+    group = group,
+    buffer = bufnr,
+    callback = function()
+      if not vim.bo[bufnr].modified then
+        return
+      end
+      buffer.reapply_dirty_inline(bufnr)
+    end,
+  })
+  vim.api.nvim_create_autocmd('InsertLeave', {
     group = group,
     buffer = bufnr,
     callback = function()
       if vim.bo[bufnr].modified then
-        buffer.clear_marks(bufnr)
+        buffer.reapply_dirty_inline(bufnr)
       end
     end,
   })