feat(plugin): add tab completion for :Pending auth subcommands

`:Pending auth <Tab>` completes `gcal gtasks clear reset`;
`:Pending auth <backend> <Tab>` completes `clear reset`.

lua/pending/buffer.lua

@@ -133,6 +133,7 @@ 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

lua/pending/init.lua

@@ -83,6 +83,16 @@ local function _save_and_notify()
   M._recompute_counts()
 end
 
+---@return boolean
+local function require_saved()
+  local bufnr = buffer.bufnr()
+  if bufnr and vim.bo[bufnr].modified then
+    log.warn('save changes first (:w)')
+    return false
+  end
+  return true
+end
+
 ---@return pending.Counts
 function M.counts()
   if not _counts then
@@ -175,6 +185,9 @@ end
 ---@param pred_str string
 ---@return nil
 function M.filter(pred_str)
+  if not require_saved() then
+    return
+  end
   if pred_str == 'clear' or pred_str == '' then
     buffer.set_filter({}, {})
     local bufnr = buffer.bufnr()
@@ -243,6 +256,9 @@ function M._setup_buf_mappings(bufnr)
       M.toggle_complete()
     end,
     view = function()
+      if not require_saved() then
+        return
+      end
       buffer.toggle_view()
     end,
     priority = function()
@@ -255,6 +271,9 @@ function M._setup_buf_mappings(bufnr)
       M.undo_write()
     end,
     filter = function()
+      if not require_saved() then
+        return
+      end
       vim.ui.input({ prompt = 'Filter: ' }, function(input)
         if input then
           M.filter(input)
@@ -370,6 +389,9 @@ end
 
 ---@return nil
 function M.undo_write()
+  if not require_saved() then
+    return
+  end
   local s = get_store()
   local stack = s:undo_stack()
   if #stack == 0 then
@@ -388,6 +410,9 @@ function M.toggle_complete()
   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
@@ -435,6 +460,9 @@ end
 function M.done(id_str)
   local id
   if not id_str or id_str == '' then
+    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
@@ -443,7 +471,6 @@ function M.done(id_str)
     end
     id = meta[row].id
     if not id then
-      log.error('Task has no ID — save the buffer first.')
       return
     end
   else
@@ -493,6 +520,9 @@ function M.toggle_priority()
   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
@@ -525,6 +555,9 @@ function M.prompt_date()
   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
@@ -885,22 +918,33 @@ function M.edit(id_str, rest)
   log.info('Task #' .. id .. ' updated: ' .. table.concat(feedback, ', '))
 end
 
+---@param args? string
 ---@return nil
-function M.auth()
+function M.auth(args)
   local oauth = require('pending.sync.oauth')
-  vim.ui.select({ 'Google Tasks', 'Google Calendar', 'Google Tasks and Google Calendar' }, {
-    prompt = 'Authenticate with:',
-  }, function(choice)
-    if not choice then
-      return
-    end
+  local parts = {}
+  for w in (args or ''):gmatch('%S+') do
+    table.insert(parts, w)
+  end
+  local action = parts[#parts]
+  if action == parts[1] and (action == 'gtasks' or action == 'gcal') then
+    action = nil
+  end
+
+  if action == 'clear' then
+    oauth.google_client:clear_tokens()
+    log.info('OAuth tokens cleared — run :Pending auth to re-authenticate.')
+  elseif action == 'reset' then
+    oauth.google_client:_wipe()
+    log.info('OAuth tokens and credentials cleared — run :Pending auth to set up from scratch.')
+  else
     local creds = oauth.google_client:resolve_credentials()
     if creds.client_id == oauth.BUNDLED_CLIENT_ID then
       oauth.google_client:setup()
     else
       oauth.google_client:auth()
     end
-  end)
+  end
 end
 
 ---@param args string
@@ -919,7 +963,7 @@ function M.command(args)
     local id_str, edit_rest = rest:match('^(%S+)%s*(.*)')
     M.edit(id_str, edit_rest)
   elseif cmd == 'auth' then
-    M.auth()
+    M.auth(rest)
   elseif SYNC_BACKEND_SET[cmd] then
     local action = rest:match('^(%S+)')
     run_sync(cmd, action)

lua/pending/sync/gcal.lua

@@ -134,16 +134,7 @@ local function with_token(callback)
   oauth.async(function()
     local token = oauth.google_client:get_access_token()
     if not token then
-      oauth.google_client:auth(function()
-        oauth.async(function()
-          local fresh = oauth.google_client:get_access_token()
-          if fresh then
-            callback(fresh)
-          else
-            log.error(oauth.google_client.name .. ': authorization failed or was cancelled')
-          end
-        end)
-      end)
+      log.warn('not authenticated — run :Pending auth')
       return
     end
     callback(token)

lua/pending/sync/gtasks.lua

@@ -404,16 +404,7 @@ local function with_token(callback)
   oauth.async(function()
     local token = oauth.google_client:get_access_token()
     if not token then
-      oauth.google_client:auth(function()
-        oauth.async(function()
-          local fresh = oauth.google_client:get_access_token()
-          if fresh then
-            callback(fresh)
-          else
-            log.error(oauth.google_client.name .. ': authorization failed or was cancelled')
-          end
-        end)
-      end)
+      log.warn('not authenticated — run :Pending auth')
       return
     end
     callback(token)

lua/pending/sync/oauth.lua

@@ -496,6 +496,11 @@ function OAuthClient:_wipe()
   os.remove(vim.fn.stdpath('data') .. '/pending/google_credentials.json')
 end
 
+---@return nil
+function OAuthClient:clear_tokens()
+  os.remove(self:token_path())
+end
+
 ---@param opts { name: string, scope: string, port: integer, config_key: string }
 ---@return pending.OAuthClient
 function M.new(opts)

plugin/pending.lua

@@ -213,6 +213,21 @@ end, {
     if cmd_line:match('^Pending%s+edit') then
       return complete_edit(arg_lead, cmd_line)
     end
+    if cmd_line:match('^Pending%s+auth') then
+      local after_auth = cmd_line:match('^Pending%s+auth%s+(.*)') or ''
+      local parts = {}
+      for w in after_auth:gmatch('%S+') do
+        table.insert(parts, w)
+      end
+      local trailing = after_auth:match('%s$')
+      if #parts == 0 or (#parts == 1 and not trailing) then
+        return filter_candidates(arg_lead, { 'gcal', 'gtasks', 'clear', 'reset' })
+      end
+      if #parts == 1 or (#parts == 2 and not trailing) then
+        return filter_candidates(arg_lead, { 'clear', 'reset' })
+      end
+      return {}
+    end
     local backend_set = pending.sync_backend_set()
     local matched_backend = cmd_line:match('^Pending%s+(%S+)')
     if matched_backend and backend_set[matched_backend] then