diff --git a/autoload/vital/_lsp.vim b/autoload/vital/_lsp.vim
new file mode 100644
index 000000000..55104952e
--- /dev/null
+++ b/autoload/vital/_lsp.vim
@@ -0,0 +1,9 @@
+let s:_plugin_name = expand('<sfile>:t:r')
+
+function! vital#{s:_plugin_name}#new() abort
+  return vital#{s:_plugin_name[1:]}#new()
+endfunction
+
+function! vital#{s:_plugin_name}#function(funcname) abort
+  silent! return function(a:funcname)
+endfunction
diff --git a/autoload/vital/_lsp/VS/Vim/Buffer.vim b/autoload/vital/_lsp/VS/Vim/Buffer.vim
new file mode 100644
index 000000000..18717c964
--- /dev/null
+++ b/autoload/vital/_lsp/VS/Vim/Buffer.vim
@@ -0,0 +1,79 @@
+" ___vital___
+" NOTE: lines between '" ___vital___' is generated by :Vitalize.
+" Do not modify the code nor insert new lines before '" ___vital___'
+function! s:_SID() abort
+  return matchstr(expand('<sfile>'), '<SNR>\zs\d\+\ze__SID$')
+endfunction
+execute join(['function! vital#_lsp#VS#Vim#Buffer#import() abort', printf("return map({'get_line_count': '', 'do': '', 'create': '', 'load': ''}, \"vital#_lsp#function('<SNR>%s_' . v:key)\")", s:_SID()), 'endfunction'], "\n")
+delfunction s:_SID
+" ___vital___
+let s:Do = { -> {} }
+
+let g:___VS_Vim_Buffer_id = get(g:, '___VS_Vim_Buffer_id', 0)
+
+"
+" get_line_count
+"
+if exists('*nvim_buf_line_count')
+  function! s:get_line_count(bufnr) abort
+    return nvim_buf_line_count(a:bufnr)
+  endfunction
+elseif has('patch-8.2.0019')
+  function! s:get_line_count(bufnr) abort
+    return getbufinfo(a:bufnr)[0].linecount
+  endfunction
+else
+  function! s:get_line_count(bufnr) abort
+    if bufnr('%') == bufnr(a:bufnr)
+      return line('$')
+    endif
+    return len(getbufline(a:bufnr, '^', '$'))
+  endfunction
+endif
+
+"
+" create
+"
+function! s:create(...) abort
+  let g:___VS_Vim_Buffer_id += 1
+  let l:bufnr = bufnr(printf('VS.Vim.Buffer: %s: %s',
+  \   g:___VS_Vim_Buffer_id,
+  \   get(a:000, 0, 'VS.Vim.Buffer.Default')
+  \ ), v:true)
+  call s:load(l:bufnr)
+  return l:bufnr
+endfunction
+
+"
+" load
+"
+if exists('*bufload')
+  function! s:load(bufnr_or_path) abort
+    call bufload(bufnr(a:bufnr_or_path, v:true))
+  endfunction
+else
+  function! s:load(bufnr_or_path) abort
+    call s:do(bufnr(a:bufnr_or_path, v:true), { -> {} })
+  endfunction
+endif
+
+"
+" do
+"
+function! s:do(bufnr, func) abort
+  let l:curr_bufnr = bufnr('%')
+  if l:curr_bufnr == a:bufnr
+    call a:func()
+    return
+  endif
+
+  try
+    execute printf('noautocmd keepalt keepjumps %sbuffer', a:bufnr)
+    call a:func()
+  catch /.*/
+    echomsg string({ 'exception': v:exception, 'throwpoint': v:throwpoint })
+  finally
+    execute printf('noautocmd keepalt keepjumps %sbuffer', l:curr_bufnr)
+  endtry
+endfunction
+
diff --git a/autoload/vital/_lsp/VS/Vim/Window.vim b/autoload/vital/_lsp/VS/Vim/Window.vim
new file mode 100644
index 000000000..dba5b0484
--- /dev/null
+++ b/autoload/vital/_lsp/VS/Vim/Window.vim
@@ -0,0 +1,139 @@
+" ___vital___
+" NOTE: lines between '" ___vital___' is generated by :Vitalize.
+" Do not modify the code nor insert new lines before '" ___vital___'
+function! s:_SID() abort
+  return matchstr(expand('<sfile>'), '<SNR>\zs\d\+\ze__SID$')
+endfunction
+execute join(['function! vital#_lsp#VS#Vim#Window#import() abort', printf("return map({'info': '', 'do': '', 'find': '', 'scroll': '', 'screenpos': ''}, \"vital#_lsp#function('<SNR>%s_' . v:key)\")", s:_SID()), 'endfunction'], "\n")
+delfunction s:_SID
+" ___vital___
+let s:Do = { -> {} }
+
+"
+" do
+"
+function! s:do(winid, func) abort
+  let l:curr_winid = win_getid()
+  if l:curr_winid == a:winid
+    call a:func()
+    return
+  endif
+
+  if exists('*win_execute')
+    let s:Do = a:func
+    try
+      noautocmd keepalt keepjumps call win_execute(a:winid, 'call s:Do()')
+    catch /.*/
+      echomsg string({ 'exception': v:exception, 'throwpoint': v:throwpoint })
+    endtry
+    unlet s:Do
+    return
+  endif
+
+  noautocmd keepalt keepjumps call win_gotoid(a:winid)
+  try
+    call a:func()
+  catch /.*/
+    echomsg string({ 'exception': v:exception, 'throwpoint': v:throwpoint })
+  endtry
+  noautocmd keepalt keepjumps call win_gotoid(l:curr_winid)
+endfunction
+
+"
+" info
+"
+if has('nvim')
+  function! s:info(win) abort
+    let l:info = getwininfo(a:win)[0]
+    return {
+    \   'width': l:info.width,
+    \   'height': l:info.height,
+    \   'topline': l:info.topline,
+    \ }
+  endfunction
+else
+  function! s:info(win) abort
+    if index(s:_get_visible_popup_winids(), a:win) >= 0
+      let l:info = popup_getpos(a:win)
+      return {
+      \   'width': l:info.width,
+      \   'height': l:info.height,
+      \   'topline': l:info.firstline
+      \ }
+    endif
+
+    let l:ctx = {}
+    let l:ctx.info = {}
+    function! l:ctx.callback() abort
+      let self.info.width = winwidth(0)
+      let self.info.height = winheight(0)
+      let self.info.topline = line('w0')
+    endfunction
+    call s:do(a:win, { -> l:ctx.callback() })
+    return l:ctx.info
+  endfunction
+endif
+
+"
+" find
+"
+function! s:find(callback) abort
+  let l:winids = []
+  let l:winids += map(range(1, tabpagewinnr(tabpagenr(), '$')), 'win_getid(v:val)')
+  let l:winids += s:_get_visible_popup_winids()
+  return filter(l:winids, 'a:callback(v:val)')
+endfunction
+
+"
+" scroll
+"
+function! s:scroll(winid, topline) abort
+  let l:ctx = {}
+  function! l:ctx.callback(winid, topline) abort
+    let l:wininfo = s:info(a:winid)
+    let l:topline = a:topline
+    let l:topline = max([l:topline, 1])
+    let l:topline = min([l:topline, line('$') - l:wininfo.height + 1])
+
+    if l:topline == l:wininfo.topline
+      return
+    endif
+
+    if index(s:_get_visible_popup_winids(), a:winid) >= 0
+      call popup_setoptions(a:winid, {
+      \   'firstline': l:topline,
+      \ })
+    else
+      let l:delta = l:topline - l:wininfo.topline
+      let l:key = l:delta > 0 ? "\<C-e>" : "\<C-y>"
+      execute printf('noautocmd silent normal! %s', repeat(l:key, abs(l:delta)))
+    endif
+  endfunction
+  call s:do(a:winid, { -> l:ctx.callback(a:winid, a:topline) })
+endfunction
+
+"
+" screenpos
+"
+" @param {[number, number]} pos - position on the current buffer.
+"
+function! s:screenpos(pos) abort
+  let l:ui_x = wincol() - col('.')
+  let l:view = winsaveview()
+  let l:scroll_x = l:view.leftcol
+  let l:scroll_y = l:view.topline - 1
+  let l:winpos = win_screenpos(win_getid())
+  let l:origin1 = [l:winpos[0] + (a:pos[0] - l:scroll_y) - 1, l:winpos[1] + (a:pos[1] + a:pos[2] + l:ui_x - l:scroll_x) - 1]
+  return [l:origin1[0] - 1, l:origin1[1] - 1]
+endfunction
+
+"
+" _get_visible_popup_winids
+"
+function! s:_get_visible_popup_winids() abort
+  if !exists('*popup_list')
+    return []
+  endif
+  return filter(popup_list(), 'popup_getpos(v:val).visible')
+endfunction
+
diff --git a/autoload/vital/_lsp/VS/Vim/Window/FloatingWindow.vim b/autoload/vital/_lsp/VS/Vim/Window/FloatingWindow.vim
new file mode 100644
index 000000000..0b3530f7a
--- /dev/null
+++ b/autoload/vital/_lsp/VS/Vim/Window/FloatingWindow.vim
@@ -0,0 +1,344 @@
+" ___vital___
+" NOTE: lines between '" ___vital___' is generated by :Vitalize.
+" Do not modify the code nor insert new lines before '" ___vital___'
+function! s:_SID() abort
+  return matchstr(expand('<sfile>'), '<SNR>\zs\d\+\ze__SID$')
+endfunction
+execute join(['function! vital#_lsp#VS#Vim#Window#FloatingWindow#import() abort', printf("return map({'_vital_depends': '', 'is_available': '', 'new': '', '_vital_loaded': ''}, \"vital#_lsp#function('<SNR>%s_' . v:key)\")", s:_SID()), 'endfunction'], "\n")
+delfunction s:_SID
+" ___vital___
+"
+" _vital_loaded
+"
+function! s:_vital_loaded(V) abort
+  let s:Window = a:V.import('VS.Vim.Window')
+endfunction
+
+"
+" _vital_depends
+"
+function! s:_vital_depends() abort
+  return ['VS.Vim.Window']
+endfunction
+
+"
+" managed floating windows.
+"
+let s:floating_windows = {}
+
+"
+" is_available
+"
+function! s:is_available() abort
+  if has('nvim')
+    return v:true
+  endif
+  return exists('*popup_create') && exists('*popup_hide') && exists('*popup_move') && exists('*popup_getpos')
+endfunction
+
+"
+" new
+"
+function! s:new(...) abort
+  call s:_init()
+
+  return s:FloatingWindow.new(get(a:000, 0, {}))
+endfunction
+
+"
+" _notify_opened
+"
+" @param {number} winid
+" @param {VS.Vim.Window.FloatingWindow} floating_window
+"
+function! s:_notify_opened(winid, floating_window) abort
+  let s:floating_windows[a:winid] = a:floating_window
+  call a:floating_window._on_opened()
+endfunction
+
+"
+" _notify_closed
+"
+function! s:_notify_closed() abort
+  for [l:winid, l:floating_window] in items(s:floating_windows)
+    if winheight(l:winid) == -1
+      call l:floating_window._on_closed()
+      unlet s:floating_windows[l:winid]
+    endif
+  endfor
+endfunction
+
+let s:FloatingWindow = {}
+
+"
+" new
+"
+" @param {function?} args.on_opened
+" @param {function?} args.on_closed
+"
+function! s:FloatingWindow.new(args) abort
+  return extend(deepcopy(s:FloatingWindow), {
+  \   '_winid': v:null,
+  \   '_bufnr': v:null,
+  \   '_vars': {},
+  \   '_on_opened': get(a:args, 'on_opened', { -> {} }),
+  \   '_on_closed': get(a:args, 'on_closed', { -> {} }),
+  \ })
+endfunction
+
+"
+" get_size
+"
+" @param {number?} args.minwidth
+" @param {number?} args.maxwidth
+" @param {number?} args.minheight
+" @param {number?} args.maxheight
+"
+function! s:FloatingWindow.get_size(args) abort
+  if self._bufnr is# v:null
+    throw 'VS.Vim.Window.FloatingWindow: Failed to detect bufnr.'
+  endif
+
+  let l:maxwidth = get(a:args, 'maxwidth', -1)
+  let l:minwidth = get(a:args, 'minwidth', -1)
+  let l:maxheight = get(a:args, 'maxheight', -1)
+  let l:minheight = get(a:args, 'minheight', -1)
+  let l:lines = getbufline(self._bufnr, '^', '$')
+
+  " width
+  let l:width = 0
+  for l:line in l:lines
+    let l:width = max([l:width, strdisplaywidth(l:line)])
+  endfor
+
+  let l:width = l:minwidth == -1 ? l:width : max([l:minwidth, l:width])
+  let l:width = l:maxwidth == -1 ? l:width : min([l:maxwidth, l:width])
+
+  " height
+  let l:height = 0
+  for l:line in l:lines
+    let l:height += max([1, float2nr(ceil(strdisplaywidth(l:line) / str2float('' . l:width)))])
+  endfor
+  let l:height = l:minheight == -1 ? l:height : max([l:minheight, l:height])
+  let l:height = l:maxheight == -1 ? l:height : min([l:maxheight, l:height])
+
+  return {
+  \   'width': max([1, l:width]),
+  \   'height': max([1, l:height]),
+  \ }
+endfunction
+
+"
+" set_bufnr
+"
+" @param {number} bufnr
+"
+function! s:FloatingWindow.set_bufnr(bufnr) abort
+  let self._bufnr = a:bufnr
+endfunction
+
+"
+" get_bufnr
+"
+function! s:FloatingWindow.get_bufnr() abort
+  return self._bufnr
+endfunction
+
+"
+" get_winid
+"
+function! s:FloatingWindow.get_winid() abort
+  if self.is_visible()
+    return self._winid
+  endif
+  return v:null
+endfunction
+
+"
+" set_var
+"
+" @param {string}  key
+" @param {unknown} value
+"
+function! s:FloatingWindow.set_var(key, value) abort
+  let self._vars[a:key] = a:value
+  if self.is_visible()
+    call setwinvar(self._winid, a:key, a:value)
+  endif
+endfunction
+
+"
+" get_var
+"
+" @param {string} key
+"
+function! s:FloatingWindow.get_var(key) abort
+  return self._vars[a:key]
+endfunction
+
+"
+" open
+"
+" @param {number} args.row 0-based indexing
+" @param {number} args.col 0-based indexing
+" @param {number} args.width
+" @param {number} args.height
+"
+function! s:FloatingWindow.open(args) abort
+  let l:style = {
+  \   'row': a:args.row,
+  \   'col': a:args.col,
+  \   'width': a:args.width,
+  \   'height': a:args.height,
+  \ }
+
+  if self.is_visible()
+    call s:_move(self._winid, l:style)
+  else
+    let self._winid = s:_open(self._bufnr, l:style, { -> self._on_closed() })
+    for [l:key, l:value] in items(self._vars)
+      call setwinvar(self._winid, l:key, l:value)
+    endfor
+    call s:_notify_opened(self._winid, self)
+  endif
+endfunction
+
+"
+" close
+"
+function! s:FloatingWindow.close() abort
+  if self.is_visible()
+    call s:_close(self._winid)
+  endif
+  let self._winid = v:null
+endfunction
+
+"
+" enter
+"
+function! s:FloatingWindow.enter() abort
+  call s:_enter(self._winid)
+endfunction
+
+"
+" is_visible
+"
+function! s:FloatingWindow.is_visible() abort
+  return s:_exists(self._winid) ? v:true : v:false
+endfunction
+
+"
+" open
+"
+if has('nvim')
+  function! s:_open(buf, style, callback) abort
+    return nvim_open_win(a:buf, v:false, s:_style(a:style))
+  endfunction
+else
+  function! s:_open(buf, style, callback) abort
+    return popup_create(a:buf, extend(s:_style(a:style), {
+    \  'callback': a:callback,
+    \ }, 'force'))
+  endfunction
+endif
+
+"
+" close
+"
+if has('nvim')
+  function! s:_close(win) abort
+    call nvim_win_close(a:win, v:true)
+    call s:_notify_closed()
+  endfunction
+else
+  function! s:_close(win) abort
+    call popup_close(a:win)
+  endfunction
+endif
+
+"
+" move
+"
+if has('nvim')
+  function! s:_move(win, style) abort
+    call nvim_win_set_config(a:win, s:_style(a:style))
+  endfunction
+else
+  function! s:_move(win, style) abort
+    call popup_move(a:win, s:_style(a:style))
+  endfunction
+endif
+
+"
+" enter
+"
+if has('nvim')
+  function! s:_enter(win) abort
+    call win_gotoid(a:win)
+  endfunction
+else
+  function! s:_enter(win) abort
+    " not supported.
+  endfunction
+endif
+
+"
+" exists
+"
+if has('nvim')
+  function! s:_exists(win) abort
+    return type(a:win) == type(0) && nvim_win_is_valid(a:win) && nvim_win_get_number(a:win) != -1
+  endfunction
+else
+  function! s:_exists(win) abort
+    return type(a:win) == type(0) && winheight(a:win) != -1
+  endfunction
+endif
+
+"
+" style
+"
+if has('nvim')
+  function! s:_style(style) abort
+    return {
+    \   'relative': 'editor',
+    \   'width': a:style.width,
+    \   'height': a:style.height,
+    \   'row': a:style.row,
+    \   'col': a:style.col,
+    \   'focusable': v:true,
+    \   'style': 'minimal',
+    \ }
+  endfunction
+else
+  function! s:_style(style) abort
+    return {
+    \   'line': a:style.row + 1,
+    \   'col': a:style.col + 1,
+    \   'pos': 'topleft',
+    \   'moved': [0, 0, 0],
+    \   'scrollbar': 0,
+    \   'maxwidth': a:style.width,
+    \   'maxheight': a:style.height,
+    \   'minwidth': a:style.width,
+    \   'minheight': a:style.height,
+    \   'tabpage': 0,
+    \ }
+  endfunction
+endif
+
+"
+" init
+"
+let s:has_init = v:false
+function! s:_init() abort
+  if s:has_init || !has('nvim')
+    return
+  endif
+  let s:has_init = v:true
+  augroup printf('<sfile>')
+    autocmd!
+    autocmd WinEnter * call <SID>_notify_closed()
+  augroup END
+endfunction
+
diff --git a/autoload/vital/lsp.vim b/autoload/vital/lsp.vim
new file mode 100644
index 000000000..6730f4e0a
--- /dev/null
+++ b/autoload/vital/lsp.vim
@@ -0,0 +1,330 @@
+let s:plugin_name = expand('<sfile>:t:r')
+let s:vital_base_dir = expand('<sfile>:h')
+let s:project_root = expand('<sfile>:h:h:h')
+let s:is_vital_vim = s:plugin_name is# 'vital'
+
+let s:loaded = {}
+let s:cache_sid = {}
+
+function! vital#{s:plugin_name}#new() abort
+  return s:new(s:plugin_name)
+endfunction
+
+function! vital#{s:plugin_name}#import(...) abort
+  if !exists('s:V')
+    let s:V = s:new(s:plugin_name)
+  endif
+  return call(s:V.import, a:000, s:V)
+endfunction
+
+let s:Vital = {}
+
+function! s:new(plugin_name) abort
+  let base = deepcopy(s:Vital)
+  let base._plugin_name = a:plugin_name
+  return base
+endfunction
+
+function! s:vital_files() abort
+  if !exists('s:vital_files')
+    let s:vital_files = map(
+    \   s:is_vital_vim ? s:_global_vital_files() : s:_self_vital_files(),
+    \   'fnamemodify(v:val, ":p:gs?[\\\\/]?/?")')
+  endif
+  return copy(s:vital_files)
+endfunction
+let s:Vital.vital_files = function('s:vital_files')
+
+function! s:import(name, ...) abort dict
+  let target = {}
+  let functions = []
+  for a in a:000
+    if type(a) == type({})
+      let target = a
+    elseif type(a) == type([])
+      let functions = a
+    endif
+    unlet a
+  endfor
+  let module = self._import(a:name)
+  if empty(functions)
+    call extend(target, module, 'keep')
+  else
+    for f in functions
+      if has_key(module, f) && !has_key(target, f)
+        let target[f] = module[f]
+      endif
+    endfor
+  endif
+  return target
+endfunction
+let s:Vital.import = function('s:import')
+
+function! s:load(...) abort dict
+  for arg in a:000
+    let [name; as] = type(arg) == type([]) ? arg[: 1] : [arg, arg]
+    let target = split(join(as, ''), '\W\+')
+    let dict = self
+    let dict_type = type({})
+    while !empty(target)
+      let ns = remove(target, 0)
+      if !has_key(dict, ns)
+        let dict[ns] = {}
+      endif
+      if type(dict[ns]) == dict_type
+        let dict = dict[ns]
+      else
+        unlet dict
+        break
+      endif
+    endwhile
+    if exists('dict')
+      call extend(dict, self._import(name))
+    endif
+    unlet arg
+  endfor
+  return self
+endfunction
+let s:Vital.load = function('s:load')
+
+function! s:unload() abort dict
+  let s:loaded = {}
+  let s:cache_sid = {}
+  unlet! s:vital_files
+endfunction
+let s:Vital.unload = function('s:unload')
+
+function! s:exists(name) abort dict
+  if a:name !~# '\v^\u\w*%(\.\u\w*)*$'
+    throw 'vital: Invalid module name: ' . a:name
+  endif
+  return s:_module_path(a:name) isnot# ''
+endfunction
+let s:Vital.exists = function('s:exists')
+
+function! s:search(pattern) abort dict
+  let paths = s:_extract_files(a:pattern, self.vital_files())
+  let modules = sort(map(paths, 's:_file2module(v:val)'))
+  return uniq(modules)
+endfunction
+let s:Vital.search = function('s:search')
+
+function! s:plugin_name() abort dict
+  return self._plugin_name
+endfunction
+let s:Vital.plugin_name = function('s:plugin_name')
+
+function! s:_self_vital_files() abort
+  let builtin = printf('%s/__%s__/', s:vital_base_dir, s:plugin_name)
+  let installed = printf('%s/_%s/', s:vital_base_dir, s:plugin_name)
+  let base = builtin . ',' . installed
+  return split(globpath(base, '**/*.vim', 1), "\n")
+endfunction
+
+function! s:_global_vital_files() abort
+  let pattern = 'autoload/vital/__*__/**/*.vim'
+  return split(globpath(&runtimepath, pattern, 1), "\n")
+endfunction
+
+function! s:_extract_files(pattern, files) abort
+  let tr = {'.': '/', '*': '[^/]*', '**': '.*'}
+  let target = substitute(a:pattern, '\.\|\*\*\?', '\=tr[submatch(0)]', 'g')
+  let regexp = printf('autoload/vital/[^/]\+/%s.vim$', target)
+  return filter(a:files, 'v:val =~# regexp')
+endfunction
+
+function! s:_file2module(file) abort
+  let filename = fnamemodify(a:file, ':p:gs?[\\/]?/?')
+  let tail = matchstr(filename, 'autoload/vital/_\w\+/\zs.*\ze\.vim$')
+  return join(split(tail, '[\\/]\+'), '.')
+endfunction
+
+" @param {string} name e.g. Data.List
+function! s:_import(name) abort dict
+  if has_key(s:loaded, a:name)
+    return copy(s:loaded[a:name])
+  endif
+  let module = self._get_module(a:name)
+  if has_key(module, '_vital_created')
+    call module._vital_created(module)
+  endif
+  let export_module = filter(copy(module), 'v:key =~# "^\\a"')
+  " Cache module before calling module._vital_loaded() to avoid cyclic
+  " dependences but remove the cache if module._vital_loaded() fails.
+  " let s:loaded[a:name] = export_module
+  let s:loaded[a:name] = export_module
+  if has_key(module, '_vital_loaded')
+    try
+      call module._vital_loaded(vital#{s:plugin_name}#new())
+    catch
+      unlet s:loaded[a:name]
+      throw 'vital: fail to call ._vital_loaded(): ' . v:exception . " from:\n" . s:_format_throwpoint(v:throwpoint)
+    endtry
+  endif
+  return copy(s:loaded[a:name])
+endfunction
+let s:Vital._import = function('s:_import')
+
+function! s:_format_throwpoint(throwpoint) abort
+  let funcs = []
+  let stack = matchstr(a:throwpoint, '^function \zs.*, .\{-} \d\+$')
+  for line in split(stack, '\.\.')
+    let m = matchlist(line, '^\(.\+\)\%(\[\(\d\+\)\]\|, .\{-} \(\d\+\)\)$')
+    if !empty(m)
+      let [name, lnum, lnum2] = m[1:3]
+      if empty(lnum)
+        let lnum = lnum2
+      endif
+      let info = s:_get_func_info(name)
+      if !empty(info)
+        let attrs = empty(info.attrs) ? '' : join([''] + info.attrs)
+        let flnum = info.lnum == 0 ? '' : printf(' Line:%d', info.lnum + lnum)
+        call add(funcs, printf('function %s(...)%s Line:%d (%s%s)',
+        \        info.funcname, attrs, lnum, info.filename, flnum))
+        continue
+      endif
+    endif
+    " fallback when function information cannot be detected
+    call add(funcs, line)
+  endfor
+  return join(funcs, "\n")
+endfunction
+
+function! s:_get_func_info(name) abort
+  let name = a:name
+  if a:name =~# '^\d\+$'  " is anonymous-function
+    let name = printf('{%s}', a:name)
+  elseif a:name =~# '^<lambda>\d\+$'  " is lambda-function
+    let name = printf("{'%s'}", a:name)
+  endif
+  if !exists('*' . name)
+    return {}
+  endif
+  let body = execute(printf('verbose function %s', name))
+  let lines = split(body, "\n")
+  let signature = matchstr(lines[0], '^\s*\zs.*')
+  let [_, file, lnum; __] = matchlist(lines[1],
+  \   '^\t\%(Last set from\|.\{-}:\)\s*\zs\(.\{-}\)\%( \S\+ \(\d\+\)\)\?$')
+  return {
+  \   'filename': substitute(file, '[/\\]\+', '/', 'g'),
+  \   'lnum': 0 + lnum,
+  \   'funcname': a:name,
+  \   'arguments': split(matchstr(signature, '(\zs.*\ze)'), '\s*,\s*'),
+  \   'attrs': filter(['dict', 'abort', 'range', 'closure'], 'signature =~# (").*" . v:val)'),
+  \ }
+endfunction
+
+" s:_get_module() returns module object wihch has all script local functions.
+function! s:_get_module(name) abort dict
+  let funcname = s:_import_func_name(self.plugin_name(), a:name)
+  try
+    return call(funcname, [])
+  catch /^Vim\%((\a\+)\)\?:E117:/
+    return s:_get_builtin_module(a:name)
+  endtry
+endfunction
+
+function! s:_get_builtin_module(name) abort
+ return s:sid2sfuncs(s:_module_sid(a:name))
+endfunction
+
+if s:is_vital_vim
+  " For vital.vim, we can use s:_get_builtin_module directly
+  let s:Vital._get_module = function('s:_get_builtin_module')
+else
+  let s:Vital._get_module = function('s:_get_module')
+endif
+
+function! s:_import_func_name(plugin_name, module_name) abort
+  return printf('vital#_%s#%s#import', a:plugin_name, s:_dot_to_sharp(a:module_name))
+endfunction
+
+function! s:_module_sid(name) abort
+  let path = s:_module_path(a:name)
+  if !filereadable(path)
+    throw 'vital: module not found: ' . a:name
+  endif
+  let vital_dir = s:is_vital_vim ? '__\w\+__' : printf('_\{1,2}%s\%%(__\)\?', s:plugin_name)
+  let base = join([vital_dir, ''], '[/\\]\+')
+  let p = base . substitute('' . a:name, '\.', '[/\\\\]\\+', 'g')
+  let sid = s:_sid(path, p)
+  if !sid
+    call s:_source(path)
+    let sid = s:_sid(path, p)
+    if !sid
+      throw printf('vital: cannot get <SID> from path: %s', path)
+    endif
+  endif
+  return sid
+endfunction
+
+function! s:_module_path(name) abort
+  return get(s:_extract_files(a:name, s:vital_files()), 0, '')
+endfunction
+
+function! s:_module_sid_base_dir() abort
+  return s:is_vital_vim ? &rtp : s:project_root
+endfunction
+
+function! s:_dot_to_sharp(name) abort
+  return substitute(a:name, '\.', '#', 'g')
+endfunction
+
+function! s:_source(path) abort
+  execute 'source' fnameescape(a:path)
+endfunction
+
+" @vimlint(EVL102, 1, l:_)
+" @vimlint(EVL102, 1, l:__)
+function! s:_sid(path, filter_pattern) abort
+  let unified_path = s:_unify_path(a:path)
+  if has_key(s:cache_sid, unified_path)
+    return s:cache_sid[unified_path]
+  endif
+  for line in filter(split(execute(':scriptnames'), "\n"), 'v:val =~# a:filter_pattern')
+    let [_, sid, path; __] = matchlist(line, '^\s*\(\d\+\):\s\+\(.\+\)\s*$')
+    if s:_unify_path(path) is# unified_path
+      let s:cache_sid[unified_path] = sid
+      return s:cache_sid[unified_path]
+    endif
+  endfor
+  return 0
+endfunction
+
+if filereadable(expand('<sfile>:r') . '.VIM') " is case-insensitive or not
+  let s:_unify_path_cache = {}
+  " resolve() is slow, so we cache results.
+  " Note: On windows, vim can't expand path names from 8.3 formats.
+  " So if getting full path via <sfile> and $HOME was set as 8.3 format,
+  " vital load duplicated scripts. Below's :~ avoid this issue.
+  function! s:_unify_path(path) abort
+    if has_key(s:_unify_path_cache, a:path)
+      return s:_unify_path_cache[a:path]
+    endif
+    let value = tolower(fnamemodify(resolve(fnamemodify(
+    \                   a:path, ':p')), ':~:gs?[\\/]?/?'))
+    let s:_unify_path_cache[a:path] = value
+    return value
+  endfunction
+else
+  function! s:_unify_path(path) abort
+    return resolve(fnamemodify(a:path, ':p:gs?[\\/]?/?'))
+  endfunction
+endif
+
+" copied and modified from Vim.ScriptLocal
+let s:SNR = join(map(range(len("\<SNR>")), '"[\\x" . printf("%0x", char2nr("\<SNR>"[v:val])) . "]"'), '')
+function! s:sid2sfuncs(sid) abort
+  let fs = split(execute(printf(':function /^%s%s_', s:SNR, a:sid)), "\n")
+  let r = {}
+  let pattern = printf('\m^function\s<SNR>%d_\zs\w\{-}\ze(', a:sid)
+  for fname in map(fs, 'matchstr(v:val, pattern)')
+    let r[fname] = function(s:_sfuncname(a:sid, fname))
+  endfor
+  return r
+endfunction
+
+"" Return funcname of script local functions with SID
+function! s:_sfuncname(sid, funcname) abort
+  return printf('<SNR>%s_%s', a:sid, a:funcname)
+endfunction
diff --git a/autoload/vital/lsp.vital b/autoload/vital/lsp.vital
new file mode 100644
index 000000000..24db5525c
--- /dev/null
+++ b/autoload/vital/lsp.vital
@@ -0,0 +1,5 @@
+lsp
+274654a8153a620b94c7e6869e838d43b8d9e701
+
+VS.Vim.Window.FloatingWindow
+VS.Vim.Buffer