fix(diff): preserve due/rec when absent from buffer line (#68)

* fix(diff): preserve due/rec when absent from buffer line

Problem: `diff.apply` overwrites `task.due` and `task.recur` with `nil`
whenever those fields aren't present as inline tokens in the buffer line.
Because metadata is rendered as virtual text (never in the line text),
every description edit silently clears due dates and recurrence rules.

Solution: Only update `due`, `recur`, and `recur_mode` in the existing-
task branch when the parsed entry actually contains them (non-nil). Users
can still set/change these inline by typing `due:<date>` or `rec:<rule>`;
clearing them requires `:Pending edit <id> -due`.

* refactor: remove project-local store discovery

Problem: `store.resolve_path()` searched upward for `.pending.json`,
silently splitting task data across multiple files depending on CWD.

Solution: `resolve_path()` now always returns `config.get().data_path`.
Remove `M.init()` and the `:Pending init` command and tab-completion
entry. Remove the project-local health message.

* refactor: extract log.lua, standardise [pending.nvim]: prefix

Problem: Notifications were scattered across files using bare
`vim.notify` with inconsistent `pending.nvim: ` prefixes, and the
`debug` guard in `textobj.lua` and `init.lua` was duplicated inline.

Solution: Add `lua/pending/log.lua` with `info`, `warn`, `error`, and
`debug` functions (prefix `[pending.nvim]: `). `log.debug` only fires
when `config.debug = true` or the optional `override` param is `true`.
Replace all `vim.notify` callsites and remove inline debug guards.

* feat(parse): configurable input date formats

Problem: `due:` only accepted ISO `YYYY-MM-DD` and built-in keywords;
users expecting locale-style dates like `03/15/2026` or `15-Mar-2026`
had no way to configure alternative input formats.

Solution: Add `input_date_formats` config field (string[]). Each entry
is a strftime-like format string supporting `%Y`, `%y`, `%m`, `%d`,
`%e`, `%b`, `%B`. Formats are tried in order after built-in keywords
fail. When no year specifier is present the current or next year is
inferred. Update vimdoc and add 8 parse_spec tests.

lua/pending/init.lua

@@ -1,5 +1,6 @@
 local buffer = require('pending.buffer')
 local diff = require('pending.diff')
+local log = require('pending.log')
 local parse = require('pending.parse')
 local store = require('pending.store')
 
@@ -328,12 +329,7 @@ function M._setup_buf_mappings(bufnr)
 
   for name, fn in pairs(motions) do
     local key = km[name]
-    if cfg.debug then
-      vim.notify(
-        ('[pending] mapping motion %s → %s (buf=%d)'):format(name, key or 'nil', bufnr),
-        vim.log.levels.INFO
-      )
-    end
+    log.debug(('mapping motion %s → %s (buf=%d)'):format(name, key or 'nil', bufnr))
     if key and key ~= false then
       vim.keymap.set({ 'n', 'x', 'o' }, key --[[@as string]], function()
         fn(vim.v.count1)
@@ -377,7 +373,7 @@ function M.undo_write()
   local s = get_store()
   local stack = s:undo_stack()
   if #stack == 0 then
-    vim.notify('Nothing to undo.', vim.log.levels.WARN)
+    log.warn('Nothing to undo.')
     return
   end
   local state = table.remove(stack)
@@ -494,7 +490,7 @@ function M.prompt_date()
         not due:match('^%d%d%d%d%-%d%d%-%d%d$')
         and not due:match('^%d%d%d%d%-%d%d%-%d%dT%d%d:%d%d$')
       then
-        vim.notify('Invalid date format. Use YYYY-MM-DD or YYYY-MM-DDThh:mm.', vim.log.levels.ERROR)
+        log.error('Invalid date format. Use YYYY-MM-DD or YYYY-MM-DDThh:mm.')
         return
       end
     end
@@ -508,14 +504,14 @@ end
 ---@return nil
 function M.add(text)
   if not text or text == '' then
-    vim.notify('Usage: :Pending add <description>', vim.log.levels.ERROR)
+    log.error('Usage: :Pending add <description>')
     return
   end
   local s = get_store()
   s:load()
   local description, metadata = parse.command_add(text)
   if not description or description == '' then
-    vim.notify('Pending must have a description.', vim.log.levels.ERROR)
+    log.error('Pending must have a description.')
     return
   end
   s:add({
@@ -530,7 +526,7 @@ function M.add(text)
   if bufnr and vim.api.nvim_buf_is_valid(bufnr) then
     buffer.render(bufnr)
   end
-  vim.notify('Pending added: ' .. description)
+  log.info('Pending added: ' .. description)
 end
 
 ---@type string[]
@@ -548,7 +544,7 @@ end
 local function run_sync(backend_name, action)
   local ok, backend = pcall(require, 'pending.sync.' .. backend_name)
   if not ok then
-    vim.notify('Unknown sync backend: ' .. backend_name, vim.log.levels.ERROR)
+    log.error('Unknown sync backend: ' .. backend_name)
     return
   end
   if not action or action == '' then
@@ -559,11 +555,11 @@ local function run_sync(backend_name, action)
       end
     end
     table.sort(actions)
-    vim.notify(backend_name .. ' actions: ' .. table.concat(actions, ', '), vim.log.levels.INFO)
+    log.info(backend_name .. ' actions: ' .. table.concat(actions, ', '))
     return
   end
   if type(backend[action]) ~= 'function' then
-    vim.notify(backend_name .. " backend has no '" .. action .. "' action", vim.log.levels.ERROR)
+    log.error(backend_name .. " backend has no '" .. action .. "' action")
     return
   end
   backend[action]()
@@ -601,7 +597,7 @@ function M.archive(days)
   end
   s:replace_tasks(kept)
   _save_and_notify()
-  vim.notify('Archived ' .. archived .. ' tasks.')
+  log.info('Archived ' .. archived .. ' tasks.')
   local bufnr = buffer.bufnr()
   if bufnr and vim.api.nvim_buf_is_valid(bufnr) then
     buffer.render(bufnr)
@@ -653,7 +649,7 @@ function M.due()
   end
 
   if #qf_items == 0 then
-    vim.notify('No due or overdue tasks.')
+    log.info('No due or overdue tasks.')
     return
   end
 
@@ -740,16 +736,15 @@ end
 ---@return nil
 function M.edit(id_str, rest)
   if not id_str or id_str == '' then
-    vim.notify(
-      'Usage: :Pending edit <id> [due:<date>] [cat:<name>] [rec:<pattern>] [+!] [-!] [-due] [-cat] [-rec]',
-      vim.log.levels.ERROR
+    log.error(
+      'Usage: :Pending edit <id> [due:<date>] [cat:<name>] [rec:<pattern>] [+!] [-!] [-due] [-cat] [-rec]'
     )
     return
   end
 
   local id = tonumber(id_str)
   if not id then
-    vim.notify('Invalid task ID: ' .. id_str, vim.log.levels.ERROR)
+    log.error('Invalid task ID: ' .. id_str)
     return
   end
 
@@ -757,14 +752,13 @@ function M.edit(id_str, rest)
   s:load()
   local task = s:get(id)
   if not task then
-    vim.notify('No task with ID ' .. id .. '.', vim.log.levels.ERROR)
+    log.error('No task with ID ' .. id .. '.')
     return
   end
 
   if not rest or rest == '' then
-    vim.notify(
-      'Usage: :Pending edit <id> [due:<date>] [cat:<name>] [rec:<pattern>] [+!] [-!] [-due] [-cat] [-rec]',
-      vim.log.levels.ERROR
+    log.error(
+      'Usage: :Pending edit <id> [due:<date>] [cat:<name>] [rec:<pattern>] [+!] [-!] [-due] [-cat] [-rec]'
     )
     return
   end
@@ -780,7 +774,7 @@ function M.edit(id_str, rest)
   for _, tok in ipairs(tokens) do
     local field, value, err = parse_edit_token(tok)
     if err then
-      vim.notify(err, vim.log.levels.ERROR)
+      log.error(err)
       return
     end
     if field == 'recur' then
@@ -831,20 +825,7 @@ function M.edit(id_str, rest)
     buffer.render(bufnr)
   end
 
-  vim.notify('Task #' .. id .. ' updated: ' .. table.concat(feedback, ', '))
-end
-
----@return nil
-function M.init()
-  local path = vim.fn.getcwd() .. '/.pending.json'
-  if vim.fn.filereadable(path) == 1 then
-    vim.notify('pending.nvim: .pending.json already exists', vim.log.levels.WARN)
-    return
-  end
-  local s = store.new(path)
-  s:load()
-  s:save()
-  vim.notify('pending.nvim: created ' .. path)
+  log.info('Task #' .. id .. ' updated: ' .. table.concat(feedback, ', '))
 end
 
 ---@param args string
@@ -872,10 +853,8 @@ function M.command(args)
     M.filter(rest)
   elseif cmd == 'undo' then
     M.undo_write()
-  elseif cmd == 'init' then
-    M.init()
   else
-    vim.notify('Unknown Pending subcommand: ' .. cmd, vim.log.levels.ERROR)
+    log.error('Unknown Pending subcommand: ' .. cmd)
   end
 end