fix: revert dev

lua/pending/health.lua

@@ -59,7 +59,7 @@ function M.check()
   end
 
   local sync_paths = vim.fn.globpath(vim.o.runtimepath, 'lua/pending/sync/*.lua', false, true)
-  if #sync_paths == 0 then
+  if #sync_paths == 0 and vim.tbl_isempty(require('pending').registered_backends()) then
     vim.health.info('No sync backends found')
   else
     for _, path in ipairs(sync_paths) do
@@ -70,6 +70,12 @@ function M.check()
         backend.health()
       end
     end
+    for rname, rbackend in pairs(require('pending').registered_backends()) do
+      if type(rbackend.health) == 'function' then
+        vim.health.start('pending.nvim: sync/' .. rname)
+        rbackend.health()
+      end
+    end
   end
 end
 

lua/pending/init.lua

@@ -1141,18 +1141,60 @@ end
 
 ---@class pending.SyncBackend
 ---@field name string
----@field auth fun(): nil
+---@field auth? fun(sub_action?: string): nil
 ---@field push? fun(): nil
 ---@field pull? fun(): nil
 ---@field sync? fun(): nil
 ---@field health? fun(): nil
 
+---@type table<string, pending.SyncBackend>
+local _registered_backends = {}
+
 ---@type string[]?
 local _sync_backends = nil
 
 ---@type table<string, true>?
 local _sync_backend_set = nil
 
+---@param name string
+---@return pending.SyncBackend?
+function M.resolve_backend(name)
+  if _registered_backends[name] then
+    return _registered_backends[name]
+  end
+  local ok, mod = pcall(require, 'pending.sync.' .. name)
+  if ok and type(mod) == 'table' and mod.name then
+    return mod
+  end
+  return nil
+end
+
+---@param backend pending.SyncBackend
+---@return nil
+function M.register_backend(backend)
+  if type(backend) ~= 'table' or type(backend.name) ~= 'string' or backend.name == '' then
+    log.error('register_backend: backend must have a non-empty `name` field')
+    return
+  end
+  local builtin_ok, builtin = pcall(require, 'pending.sync.' .. backend.name)
+  if builtin_ok and type(builtin) == 'table' and builtin.name then
+    log.error('register_backend: backend `' .. backend.name .. '` already exists as a built-in')
+    return
+  end
+  if _registered_backends[backend.name] then
+    log.error('register_backend: backend `' .. backend.name .. '` is already registered')
+    return
+  end
+  _registered_backends[backend.name] = backend
+  _sync_backends = nil
+  _sync_backend_set = nil
+end
+
+---@return table<string, pending.SyncBackend>
+function M.registered_backends()
+  return _registered_backends
+end
+
 ---@return string[], table<string, true>
 local function discover_backends()
   if _sync_backends then
@@ -1169,6 +1211,12 @@ local function discover_backends()
       _sync_backend_set[mod.name] = true
     end
   end
+  for name, _ in pairs(_registered_backends) do
+    if not _sync_backend_set[name] then
+      table.insert(_sync_backends, name)
+      _sync_backend_set[name] = true
+    end
+  end
   table.sort(_sync_backends)
   return _sync_backends, _sync_backend_set
 end
@@ -1177,8 +1225,8 @@ end
 ---@param action? string
 ---@return nil
 local function run_sync(backend_name, action)
-  local ok, backend = pcall(require, 'pending.sync.' .. backend_name)
-  if not ok then
+  local backend = M.resolve_backend(backend_name)
+  if not backend then
     log.error('Unknown sync backend: ' .. backend_name)
     return
   end
@@ -1543,8 +1591,8 @@ function M.auth(args)
   local backends_list = discover_backends()
   local auth_backends = {}
   for _, name in ipairs(backends_list) do
-    local ok, mod = pcall(require, 'pending.sync.' .. name)
-    if ok and type(mod.auth) == 'function' then
+    local mod = M.resolve_backend(name)
+    if mod and type(mod.auth) == 'function' then
       table.insert(auth_backends, { name = name, mod = mod })
     end
   end

plugin/pending.lua

@@ -304,8 +304,8 @@ end, {
       if #parts == 0 or (#parts == 1 and not trailing) then
         local auth_names = {}
         for _, b in ipairs(pending.sync_backends()) do
-          local ok, mod = pcall(require, 'pending.sync.' .. b)
-          if ok and type(mod.auth) == 'function' then
+          local mod = pending.resolve_backend(b)
+          if mod and type(mod.auth) == 'function' then
             table.insert(auth_names, b)
           end
         end
@@ -313,8 +313,8 @@ end, {
       end
       local backend_name = parts[1]
       if #parts == 1 or (#parts == 2 and not trailing) then
-        local ok, mod = pcall(require, 'pending.sync.' .. backend_name)
-        if ok and type(mod.auth_complete) == 'function' then
+        local mod = pending.resolve_backend(backend_name)
+        if mod and type(mod.auth_complete) == 'function' then
           return filter_candidates(arg_lead, mod.auth_complete())
         end
         return {}
@@ -328,8 +328,8 @@ end, {
       if not after_backend then
         return {}
       end
-      local ok, mod = pcall(require, 'pending.sync.' .. matched_backend)
-      if not ok then
+      local mod = pending.resolve_backend(matched_backend)
+      if not mod then
         return {}
       end
       local actions = {}

spec/sync_spec.lua

@@ -124,6 +124,100 @@ describe('sync', function()
     end)
   end)
 
+  describe('register_backend', function()
+    it('registers a custom backend', function()
+      pending.register_backend({ name = 'custom', pull = function() end })
+      local set = pending.sync_backend_set()
+      assert.is_true(set['custom'] == true)
+      assert.is_true(vim.tbl_contains(pending.sync_backends(), 'custom'))
+    end)
+
+    it('rejects backend without name', function()
+      local msg
+      local orig = vim.notify
+      vim.notify = function(m, level)
+        if level == vim.log.levels.ERROR then
+          msg = m
+        end
+      end
+      pending.register_backend({})
+      vim.notify = orig
+      assert.truthy(msg and msg:find('non%-empty'))
+    end)
+
+    it('rejects backend with empty name', function()
+      local msg
+      local orig = vim.notify
+      vim.notify = function(m, level)
+        if level == vim.log.levels.ERROR then
+          msg = m
+        end
+      end
+      pending.register_backend({ name = '' })
+      vim.notify = orig
+      assert.truthy(msg and msg:find('non%-empty'))
+    end)
+
+    it('rejects duplicate of built-in backend', function()
+      local msg
+      local orig = vim.notify
+      vim.notify = function(m, level)
+        if level == vim.log.levels.ERROR then
+          msg = m
+        end
+      end
+      pending.register_backend({ name = 'gcal' })
+      vim.notify = orig
+      assert.truthy(msg and msg:find('already exists'))
+    end)
+
+    it('rejects duplicate registered backend', function()
+      pending.register_backend({ name = 'dup_test', pull = function() end })
+      local msg
+      local orig = vim.notify
+      vim.notify = function(m, level)
+        if level == vim.log.levels.ERROR then
+          msg = m
+        end
+      end
+      pending.register_backend({ name = 'dup_test' })
+      vim.notify = orig
+      assert.truthy(msg and msg:find('already registered'))
+    end)
+  end)
+
+  describe('resolve_backend', function()
+    it('resolves built-in backend', function()
+      local mod = pending.resolve_backend('gcal')
+      assert.is_not_nil(mod)
+      assert.are.equal('gcal', mod.name)
+    end)
+
+    it('resolves registered backend', function()
+      local custom = { name = 'resolve_test', pull = function() end }
+      pending.register_backend(custom)
+      local mod = pending.resolve_backend('resolve_test')
+      assert.is_not_nil(mod)
+      assert.are.equal('resolve_test', mod.name)
+    end)
+
+    it('returns nil for unknown backend', function()
+      assert.is_nil(pending.resolve_backend('nonexistent_xyz'))
+    end)
+
+    it('dispatches command to registered backend', function()
+      local called = false
+      pending.register_backend({
+        name = 'cmd_test',
+        pull = function()
+          called = true
+        end,
+      })
+      pending.command('cmd_test pull')
+      assert.is_true(called)
+    end)
+  end)
+
   describe('auto-discovery', function()
     it('discovers gcal and gtasks backends', function()
       local backends = pending.sync_backends()