build: move all generator scripts to `src/gen/`

- Move all generator Lua scripts to the `src/gen/`
- Add a `.luarc.json` to `src/gen/`
- Add a `preload.lua` to `src/gen/`
  - Add `src` to `package.path` so it aligns with `.luarc.json'
- Fix all `require` statements in `src/gen/` so they are consistent:
    - `require('scripts.foo')` -> `require('gen.foo')`
    - `require('src.nvim.options')` -> `require('nvim.options')`
    - `require('api.dispatch_deprecated')` -> `require('nvim.api.dispatch_deprecated')`

25 files changed, 8820 insertions, 0 deletions

diff --git a/src/gen/c_grammar.lua b/src/gen/c_grammar.lua
new file mode 100644
index 0000000000..890c260843
--- /dev/null
+++ b/src/gen/c_grammar.lua
@@ -0,0 +1,300 @@
+-- lpeg grammar for building api metadata from a set of header files. It
+-- ignores comments and preprocessor commands and parses a very small subset
+-- of C prototypes with a limited set of types
+
+--- @class nvim.c_grammar.Proto
+--- @field [1] 'proto'
+--- @field pos integer
+--- @field endpos integer
+--- @field fast boolean
+--- @field name string
+--- @field return_type string
+--- @field parameters [string, string][]
+--- @field static true?
+--- @field inline true?
+
+--- @class nvim.c_grammar.Preproc
+--- @field [1] 'preproc'
+--- @field content string
+
+--- @class nvim.c_grammar.Empty
+--- @field [1] 'empty'
+
+--- @alias nvim.c_grammar.result
+--- | nvim.c_grammar.Proto
+--- | nvim.c_grammar.Preproc
+--- | nvim.c_grammar.Empty
+
+--- @class nvim.c_grammar
+--- @field match fun(self, input: string): nvim.c_grammar.result[]
+
+local lpeg = vim.lpeg
+
+local P, R, S, V = lpeg.P, lpeg.R, lpeg.S, lpeg.V
+local C, Ct, Cc, Cg, Cp = lpeg.C, lpeg.Ct, lpeg.Cc, lpeg.Cg, lpeg.Cp
+
+--- @param pat vim.lpeg.Pattern
+local function rep(pat)
+  return pat ^ 0
+end
+
+--- @param pat vim.lpeg.Pattern
+local function rep1(pat)
+  return pat ^ 1
+end
+
+--- @param pat vim.lpeg.Pattern
+local function opt(pat)
+  return pat ^ -1
+end
+
+local any = P(1)
+local letter = R('az', 'AZ') + S('_$')
+local num = R('09')
+local alpha = letter + num
+local nl = P('\r\n') + P('\n')
+local space = S(' \t')
+local str = P('"') * rep((P('\\') * any) + (1 - P('"'))) * P('"')
+local char = P("'") * (any - P("'")) * P("'")
+local ws = space + nl
+local wb = #-alpha -- word boundary
+local id = letter * rep(alpha)
+
+local comment_inline = P('/*') * rep(1 - P('*/')) * P('*/')
+local comment = P('//') * rep(1 - nl) * nl
+local preproc = Ct(Cc('preproc') * P('#') * Cg(rep(1 - nl) * nl, 'content'))
+
+local fill = rep(ws + comment_inline + comment + preproc)
+
+--- @param s string
+--- @return vim.lpeg.Pattern
+local function word(s)
+  return fill * P(s) * wb * fill
+end
+
+--- @param x vim.lpeg.Pattern
+local function comma1(x)
+  return x * rep(fill * P(',') * fill * x)
+end
+
+--- @param v string
+local function Pf(v)
+  return fill * P(v) * fill
+end
+
+--- @param x vim.lpeg.Pattern
+local function paren(x)
+  return P('(') * fill * x * fill * P(')')
+end
+
+local cdoc_comment = P('///') * opt(Ct(Cg(rep(space) * rep(1 - nl), 'comment')))
+
+local braces = P({
+  'S',
+  A = comment_inline + comment + preproc + str + char + (any - S('{}')),
+  S = P('{') * rep(V('A')) * rep(V('S') + V('A')) * P('}'),
+})
+
+-- stylua: ignore start
+local typed_container = P({
+  'S',
+  S = (
+    (P('Union') * paren(comma1(V('ID'))))
+    + (P('ArrayOf') * paren(id * opt(P(',') * fill * rep1(num))))
+    + (P('DictOf') * paren(id))
+    + (P('LuaRefOf') * paren(
+      paren(comma1((V('ID') + str) * rep1(ws) * opt(P('*')) * id))
+      * opt(P(',') * fill * opt(P('*')) * V('ID'))
+    ))
+    + (P('Dict') * paren(id))),
+  ID = V('S') + id,
+})
+-- stylua: ignore end
+
+local ptr_mod = word('restrict') + word('__restrict') + word('const')
+local opt_ptr = rep(Pf('*') * opt(ptr_mod))
+
+--- @param name string
+--- @param var string
+--- @return vim.lpeg.Pattern
+local function attr(name, var)
+  return Cg((P(name) * Cc(true)), var)
+end
+
+--- @param name string
+--- @param var string
+--- @return vim.lpeg.Pattern
+local function attr_num(name, var)
+  return Cg((P(name) * paren(C(rep1(num)))), var)
+end
+
+local fattr = (
+  attr_num('FUNC_API_SINCE', 'since')
+  + attr_num('FUNC_API_DEPRECATED_SINCE', 'deprecated_since')
+  + attr('FUNC_API_FAST', 'fast')
+  + attr('FUNC_API_RET_ALLOC', 'ret_alloc')
+  + attr('FUNC_API_NOEXPORT', 'noexport')
+  + attr('FUNC_API_REMOTE_ONLY', 'remote_only')
+  + attr('FUNC_API_LUA_ONLY', 'lua_only')
+  + attr('FUNC_API_TEXTLOCK_ALLOW_CMDWIN', 'textlock_allow_cmdwin')
+  + attr('FUNC_API_TEXTLOCK', 'textlock')
+  + attr('FUNC_API_REMOTE_IMPL', 'remote_impl')
+  + attr('FUNC_API_COMPOSITOR_IMPL', 'compositor_impl')
+  + attr('FUNC_API_CLIENT_IMPL', 'client_impl')
+  + attr('FUNC_API_CLIENT_IGNORE', 'client_ignore')
+  + (P('FUNC_') * rep(alpha) * opt(fill * paren(rep(1 - P(')') * any))))
+)
+
+local void = P('void') * wb
+
+local api_param_type = (
+  (word('Error') * opt_ptr * Cc('error'))
+  + (word('Arena') * opt_ptr * Cc('arena'))
+  + (word('lua_State') * opt_ptr * Cc('lstate'))
+)
+
+local ctype = C(
+  opt(word('const'))
+    * (
+      typed_container
+      -- 'unsigned' is a type modifier, and a type itself
+      + (word('unsigned char') + word('unsigned'))
+      + (word('struct') * fill * id)
+      + id
+    )
+    * opt(word('const'))
+    * opt_ptr
+)
+
+local return_type = (C(void) * fill) + ctype
+
+-- stylua: ignore start
+local params = Ct(
+  (void * #P(')'))
+  + comma1(Ct(
+      (api_param_type + ctype)
+      * fill
+      * C(id)
+      * rep(Pf('[') * rep(alpha) * Pf(']'))
+      * rep(fill * fattr)
+    ))
+    * opt(Pf(',') * P('...'))
+)
+-- stylua: ignore end
+
+local ignore_line = rep1(1 - nl) * nl
+local empty_line = Ct(Cc('empty') * nl * nl)
+
+local proto_name = opt_ptr * fill * id
+
+-- __inline is used in MSVC
+local decl_mod = (
+  Cg(word('static') * Cc(true), 'static')
+  + Cg((word('inline') + word('__inline')) * Cc(true), 'inline')
+)
+
+local proto = Ct(
+  Cg(Cp(), 'pos')
+    * Cc('proto')
+    * -#P('typedef')
+    * #alpha
+    * opt(P('DLLEXPORT') * rep1(ws))
+    * rep(decl_mod)
+    * Cg(return_type, 'return_type')
+    * fill
+    * Cg(proto_name, 'name')
+    * fill
+    * paren(Cg(params, 'parameters'))
+    * Cg(Cc(false), 'fast')
+    * rep(fill * fattr)
+    * Cg(Cp(), 'endpos')
+    * (fill * (S(';') + braces))
+)
+
+local keyset_field = Ct(
+  Cg(ctype, 'type')
+    * fill
+    * Cg(id, 'name')
+    * fill
+    * opt(P('DictKey') * paren(Cg(rep1(1 - P(')')), 'dict_key')))
+    * Pf(';')
+)
+
+local keyset = Ct(
+  P('typedef')
+    * word('struct')
+    * Pf('{')
+    * Cg(Ct(rep1(keyset_field)), 'fields')
+    * Pf('}')
+    * P('Dict')
+    * paren(Cg(id, 'keyset_name'))
+    * Pf(';')
+)
+
+local grammar =
+  Ct(rep1(empty_line + proto + cdoc_comment + comment + preproc + ws + keyset + ignore_line))
+
+if arg[1] == '--test' then
+  for i, t in ipairs({
+    'void multiqueue_put_event(MultiQueue *self, Event event) {} ',
+    'void *xmalloc(size_t size) {} ',
+    {
+      'struct tm *os_localtime_r(const time_t *restrict clock,',
+      '                          struct tm *restrict result) FUNC_ATTR_NONNULL_ALL {}',
+    },
+    {
+      '_Bool',
+      '# 163 "src/nvim/event/multiqueue.c"',
+      '    multiqueue_empty(MultiQueue *self)',
+      '{}',
+    },
+    'const char *find_option_end(const char *arg, OptIndex *opt_idxp) {}',
+    'bool semsg(const char *const fmt, ...) {}',
+    'int32_t utf_ptr2CharInfo_impl(uint8_t const *p, uintptr_t const len) {}',
+    'void ex_argdedupe(exarg_T *eap FUNC_ATTR_UNUSED) {}',
+    'static TermKeySym register_c0(TermKey *tk, TermKeySym sym, unsigned char ctrl, const char *name) {}',
+    'unsigned get_bkc_flags(buf_T *buf) {}',
+    'char *xstpcpy(char *restrict dst, const char *restrict src) {}',
+    'bool try_leave(const TryState *const tstate, Error *const err) {}',
+    'void api_set_error(ErrorType errType) {}',
+    {
+      'void nvim_subscribe(uint64_t channel_id, String event)',
+      'FUNC_API_SINCE(1) FUNC_API_DEPRECATED_SINCE(13) FUNC_API_REMOTE_ONLY',
+      '{}',
+    },
+
+    -- Do not consume leading preproc statements
+    {
+      '#line 1 "D:/a/neovim/neovim/src\\nvim/mark.h"',
+      'static __inline int mark_global_index(const char name)',
+      '  FUNC_ATTR_CONST',
+      '{}',
+    },
+    {
+      '',
+      '#line 1 "D:/a/neovim/neovim/src\\nvim/mark.h"',
+      'static __inline int mark_global_index(const char name)',
+      '{}',
+    },
+    {
+      'size_t xstrlcpy(char *__restrict dst, const char *__restrict src, size_t dsize)',
+      ' FUNC_ATTR_NONNULL_ALL',
+      ' {}',
+    },
+  }) do
+    if type(t) == 'table' then
+      t = table.concat(t, '\n') .. '\n'
+    end
+    t = t:gsub(' +', ' ')
+    local r = grammar:match(t)
+    if not r then
+      print('Test ' .. i .. ' failed')
+      print('    |' .. table.concat(vim.split(t, '\n'), '\n    |'))
+    end
+  end
+end
+
+return {
+  grammar = grammar --[[@as nvim.c_grammar]],
+  typed_container = typed_container,
+}
diff --git a/src/gen/cdoc_grammar.lua b/src/gen/cdoc_grammar.lua
new file mode 100644
index 0000000000..6a7610883b
--- /dev/null
+++ b/src/gen/cdoc_grammar.lua
@@ -0,0 +1,87 @@
+--[[!
+LPEG grammar for C doc comments
+]]
+
+--- @class nvim.cdoc.Param
+--- @field kind 'param'
+--- @field name string
+--- @field desc? string
+
+--- @class nvim.cdoc.Return
+--- @field kind 'return'
+--- @field desc string
+
+--- @class nvim.cdoc.Note
+--- @field desc? string
+
+--- @alias nvim.cdoc.grammar.result
+--- | nvim.cdoc.Param
+--- | nvim.cdoc.Return
+--- | nvim.cdoc.Note
+
+--- @class nvim.cdoc.grammar
+--- @field match fun(self, input: string): nvim.cdoc.grammar.result?
+
+local lpeg = vim.lpeg
+local P, R, S = lpeg.P, lpeg.R, lpeg.S
+local Ct, Cg = lpeg.Ct, lpeg.Cg
+
+--- @param x vim.lpeg.Pattern
+local function rep(x)
+  return x ^ 0
+end
+
+--- @param x vim.lpeg.Pattern
+local function rep1(x)
+  return x ^ 1
+end
+
+--- @param x vim.lpeg.Pattern
+local function opt(x)
+  return x ^ -1
+end
+
+local nl = P('\r\n') + P('\n')
+local ws = rep1(S(' \t') + nl)
+
+local any = P(1) -- (consume one character)
+local letter = R('az', 'AZ') + S('_$')
+local ident = letter * rep(letter + R('09'))
+
+local io = P('[') * (P('in') + P('out') + P('inout')) * P(']')
+
+--- @param x string
+local function Pf(x)
+  return opt(ws) * P(x) * opt(ws)
+end
+
+--- @type table<string,vim.lpeg.Pattern>
+local v = setmetatable({}, {
+  __index = function(_, k)
+    return lpeg.V(k)
+  end,
+})
+
+local grammar = P {
+  rep1(P('@') * v.ats),
+
+  ats = v.at_param + v.at_return + v.at_deprecated + v.at_see + v.at_brief + v.at_note + v.at_nodoc,
+
+  at_param = Ct(
+    Cg(P('param'), 'kind') * opt(io) * ws * Cg(ident, 'name') * opt(ws * Cg(rep(any), 'desc'))
+  ),
+
+  at_return = Ct(Cg(P('return'), 'kind') * opt(S('s')) * opt(ws * Cg(rep(any), 'desc'))),
+
+  at_deprecated = Ct(Cg(P('deprecated'), 'kind')),
+
+  at_see = Ct(Cg(P('see'), 'kind') * ws * opt(Pf('#')) * Cg(rep(any), 'desc')),
+
+  at_brief = Ct(Cg(P('brief'), 'kind') * ws * Cg(rep(any), 'desc')),
+
+  at_note = Ct(Cg(P('note'), 'kind') * ws * Cg(rep(any), 'desc')),
+
+  at_nodoc = Ct(Cg(P('nodoc'), 'kind')),
+}
+
+return grammar --[[@as nvim.cdoc.grammar]]
diff --git a/src/gen/cdoc_parser.lua b/src/gen/cdoc_parser.lua
new file mode 100644
index 0000000000..38314c0efd
--- /dev/null
+++ b/src/gen/cdoc_parser.lua
@@ -0,0 +1,223 @@
+local cdoc_grammar = require('gen.cdoc_grammar')
+local c_grammar = require('gen.c_grammar')
+
+--- @class nvim.cdoc.parser.param
+--- @field name string
+--- @field type string
+--- @field desc string
+
+--- @class nvim.cdoc.parser.return
+--- @field name string
+--- @field type string
+--- @field desc string
+
+--- @class nvim.cdoc.parser.note
+--- @field desc string
+
+--- @class nvim.cdoc.parser.brief
+--- @field kind 'brief'
+--- @field desc string
+
+--- @class nvim.cdoc.parser.fun
+--- @field name string
+--- @field params nvim.cdoc.parser.param[]
+--- @field returns nvim.cdoc.parser.return[]
+--- @field desc string
+--- @field deprecated? true
+--- @field since? string
+--- @field attrs? string[]
+--- @field nodoc? true
+--- @field notes? nvim.cdoc.parser.note[]
+--- @field see? nvim.cdoc.parser.note[]
+
+--- @class nvim.cdoc.parser.State
+--- @field doc_lines? string[]
+--- @field cur_obj? nvim.cdoc.parser.obj
+--- @field last_doc_item? nvim.cdoc.parser.param|nvim.cdoc.parser.return|nvim.cdoc.parser.note
+--- @field last_doc_item_indent? integer
+
+--- @alias nvim.cdoc.parser.obj
+--- | nvim.cdoc.parser.fun
+--- | nvim.cdoc.parser.brief
+
+--- If we collected any `---` lines. Add them to the existing (or new) object
+--- Used for function/class descriptions and multiline param descriptions.
+--- @param state nvim.cdoc.parser.State
+local function add_doc_lines_to_obj(state)
+  if state.doc_lines then
+    state.cur_obj = state.cur_obj or {}
+    local cur_obj = assert(state.cur_obj)
+    local txt = table.concat(state.doc_lines, '\n')
+    if cur_obj.desc then
+      cur_obj.desc = cur_obj.desc .. '\n' .. txt
+    else
+      cur_obj.desc = txt
+    end
+    state.doc_lines = nil
+  end
+end
+
+--- @param line string
+--- @param state nvim.cdoc.parser.State
+local function process_doc_line(line, state)
+  line = line:gsub('^%s+@', '@')
+
+  local parsed = cdoc_grammar:match(line)
+
+  if not parsed then
+    if line:match('^ ') then
+      line = line:sub(2)
+    end
+
+    if state.last_doc_item then
+      if not state.last_doc_item_indent then
+        state.last_doc_item_indent = #line:match('^%s*') + 1
+      end
+      state.last_doc_item.desc = (state.last_doc_item.desc or '')
+        .. '\n'
+        .. line:sub(state.last_doc_item_indent or 1)
+    else
+      state.doc_lines = state.doc_lines or {}
+      table.insert(state.doc_lines, line)
+    end
+    return
+  end
+
+  state.last_doc_item_indent = nil
+  state.last_doc_item = nil
+
+  local kind = parsed.kind
+
+  state.cur_obj = state.cur_obj or {}
+  local cur_obj = assert(state.cur_obj)
+
+  if kind == 'brief' then
+    state.cur_obj = {
+      kind = 'brief',
+      desc = parsed.desc,
+    }
+  elseif kind == 'param' then
+    state.last_doc_item_indent = nil
+    cur_obj.params = cur_obj.params or {}
+    state.last_doc_item = {
+      name = parsed.name,
+      desc = parsed.desc,
+    }
+    table.insert(cur_obj.params, state.last_doc_item)
+  elseif kind == 'return' then
+    cur_obj.returns = { {
+      desc = parsed.desc,
+    } }
+    state.last_doc_item_indent = nil
+    state.last_doc_item = cur_obj.returns[1]
+  elseif kind == 'deprecated' then
+    cur_obj.deprecated = true
+  elseif kind == 'nodoc' then
+    cur_obj.nodoc = true
+  elseif kind == 'since' then
+    cur_obj.since = parsed.desc
+  elseif kind == 'see' then
+    cur_obj.see = cur_obj.see or {}
+    table.insert(cur_obj.see, { desc = parsed.desc })
+  elseif kind == 'note' then
+    state.last_doc_item_indent = nil
+    state.last_doc_item = {
+      desc = parsed.desc,
+    }
+    cur_obj.notes = cur_obj.notes or {}
+    table.insert(cur_obj.notes, state.last_doc_item)
+  else
+    error('Unhandled' .. vim.inspect(parsed))
+  end
+end
+
+--- @param item table
+--- @param state nvim.cdoc.parser.State
+local function process_proto(item, state)
+  state.cur_obj = state.cur_obj or {}
+  local cur_obj = assert(state.cur_obj)
+  cur_obj.name = item.name
+  cur_obj.params = cur_obj.params or {}
+
+  for _, p in ipairs(item.parameters) do
+    local param = { name = p[2], type = p[1] }
+    local added = false
+    for _, cp in ipairs(cur_obj.params) do
+      if cp.name == param.name then
+        cp.type = param.type
+        added = true
+        break
+      end
+    end
+
+    if not added then
+      table.insert(cur_obj.params, param)
+    end
+  end
+
+  cur_obj.returns = cur_obj.returns or { {} }
+  cur_obj.returns[1].type = item.return_type
+
+  for _, a in ipairs({
+    'fast',
+    'remote_only',
+    'lua_only',
+    'textlock',
+    'textlock_allow_cmdwin',
+  }) do
+    if item[a] then
+      cur_obj.attrs = cur_obj.attrs or {}
+      table.insert(cur_obj.attrs, a)
+    end
+  end
+
+  cur_obj.deprecated_since = item.deprecated_since
+
+  -- Remove some arguments
+  for i = #cur_obj.params, 1, -1 do
+    local p = cur_obj.params[i]
+    if p.name == 'channel_id' or vim.tbl_contains({ 'lstate', 'arena', 'error' }, p.type) then
+      table.remove(cur_obj.params, i)
+    end
+  end
+end
+
+local M = {}
+
+--- @param filename string
+--- @return {} classes
+--- @return nvim.cdoc.parser.fun[] funs
+--- @return string[] briefs
+function M.parse(filename)
+  local funs = {} --- @type nvim.cdoc.parser.fun[]
+  local briefs = {} --- @type string[]
+  local state = {} --- @type nvim.cdoc.parser.State
+
+  local txt = assert(io.open(filename, 'r')):read('*all')
+
+  local parsed = c_grammar.grammar:match(txt)
+  for _, item in ipairs(parsed) do
+    if item.comment then
+      process_doc_line(item.comment, state)
+    else
+      add_doc_lines_to_obj(state)
+      if item[1] == 'proto' then
+        process_proto(item, state)
+        table.insert(funs, state.cur_obj)
+      end
+      local cur_obj = state.cur_obj
+      if cur_obj and not item.static then
+        if cur_obj.kind == 'brief' then
+          table.insert(briefs, cur_obj.desc)
+        end
+      end
+      state = {}
+    end
+  end
+
+  return {}, funs, briefs
+end
+
+-- M.parse('src/nvim/api/vim.c')
+
+return M
diff --git a/src/gen/dump_bin_array.lua b/src/gen/dump_bin_array.lua
new file mode 100644
index 0000000000..c6cda25e73
--- /dev/null
+++ b/src/gen/dump_bin_array.lua
@@ -0,0 +1,17 @@
+local function dump_bin_array(output, name, data)
+  output:write([[
+  static const uint8_t ]] .. name .. [[[] = {
+]])
+
+  for i = 1, #data do
+    output:write(string.byte(data, i) .. ', ')
+    if i % 10 == 0 then
+      output:write('\n  ')
+    end
+  end
+  output:write([[
+};
+]])
+end
+
+return dump_bin_array
diff --git a/src/gen/gen_api_dispatch.lua b/src/gen/gen_api_dispatch.lua
new file mode 100644
index 0000000000..a5d0890c2f
--- /dev/null
+++ b/src/gen/gen_api_dispatch.lua
@@ -0,0 +1,990 @@
+-- Example (manual) invocation:
+--
+--    make
+--    cp build/nvim_version.lua src/nvim/
+--    cd src/nvim
+--    nvim -l generators/gen_api_dispatch.lua "../../build/src/nvim/auto/api/private/dispatch_wrappers.generated.h" "../../build/src/nvim/auto/api/private/api_metadata.generated.h" "../../build/funcs_metadata.mpack" "../../build/src/nvim/auto/lua_api_c_bindings.generated.h" "../../build/src/nvim/auto/keysets_defs.generated.h" "../../build/ui_metadata.mpack" "../../build/cmake.config/auto/versiondef_git.h" "./api/autocmd.h" "./api/buffer.h" "./api/command.h" "./api/deprecated.h" "./api/extmark.h" "./api/keysets_defs.h" "./api/options.h" "./api/tabpage.h" "./api/ui.h" "./api/vim.h" "./api/vimscript.h" "./api/win_config.h" "./api/window.h" "../../build/include/api/autocmd.h.generated.h" "../../build/include/api/buffer.h.generated.h" "../../build/include/api/command.h.generated.h" "../../build/include/api/deprecated.h.generated.h" "../../build/include/api/extmark.h.generated.h" "../../build/include/api/options.h.generated.h" "../../build/include/api/tabpage.h.generated.h" "../../build/include/api/ui.h.generated.h" "../../build/include/api/vim.h.generated.h" "../../build/include/api/vimscript.h.generated.h" "../../build/include/api/win_config.h.generated.h" "../../build/include/api/window.h.generated.h"
+
+local mpack = vim.mpack
+
+local hashy = require 'gen.hashy'
+
+local pre_args = 7
+assert(#arg >= pre_args)
+-- output h file with generated dispatch functions (dispatch_wrappers.generated.h)
+local dispatch_outputf = arg[1]
+-- output h file with packed metadata (api_metadata.generated.h)
+local api_metadata_outputf = arg[2]
+-- output metadata mpack file, for use by other build scripts (funcs_metadata.mpack)
+local mpack_outputf = arg[3]
+local lua_c_bindings_outputf = arg[4] -- lua_api_c_bindings.generated.c
+local keysets_outputf = arg[5] -- keysets_defs.generated.h
+local ui_metadata_inputf = arg[6] -- ui events metadata
+local git_version_inputf = arg[7] -- git version header
+
+local functions = {}
+
+-- names of all headers relative to the source root (for inclusion in the
+-- generated file)
+local headers = {}
+
+-- set of function names, used to detect duplicates
+local function_names = {}
+
+local c_grammar = require('gen.c_grammar')
+
+local startswith = vim.startswith
+
+local function add_function(fn)
+  local public = startswith(fn.name, 'nvim_') or fn.deprecated_since
+  if public and not fn.noexport then
+    functions[#functions + 1] = fn
+    function_names[fn.name] = true
+    if
+      #fn.parameters >= 2
+      and fn.parameters[2][1] == 'Array'
+      and fn.parameters[2][2] == 'uidata'
+    then
+      -- function receives the "args" as a parameter
+      fn.receives_array_args = true
+      -- remove the args parameter
+      table.remove(fn.parameters, 2)
+    end
+    if #fn.parameters ~= 0 and fn.parameters[1][2] == 'channel_id' then
+      -- this function should receive the channel id
+      fn.receives_channel_id = true
+      -- remove the parameter since it won't be passed by the api client
+      table.remove(fn.parameters, 1)
+    end
+    if #fn.parameters ~= 0 and fn.parameters[#fn.parameters][1] == 'error' then
+      -- function can fail if the last parameter type is 'Error'
+      fn.can_fail = true
+      -- remove the error parameter, msgpack has it's own special field
+      -- for specifying errors
+      fn.parameters[#fn.parameters] = nil
+    end
+    if #fn.parameters ~= 0 and fn.parameters[#fn.parameters][1] == 'lstate' then
+      fn.has_lua_imp = true
+      fn.parameters[#fn.parameters] = nil
+    end
+    if #fn.parameters ~= 0 and fn.parameters[#fn.parameters][1] == 'arena' then
+      fn.receives_arena = true
+      fn.parameters[#fn.parameters] = nil
+    end
+  end
+end
+
+local keysets = {}
+
+local function add_keyset(val)
+  local keys = {}
+  local types = {}
+  local c_names = {}
+  local is_set_name = 'is_set__' .. val.keyset_name .. '_'
+  local has_optional = false
+  for i, field in ipairs(val.fields) do
+    local dict_key = field.dict_key or field.name
+    if field.type ~= 'Object' then
+      types[dict_key] = field.type
+    end
+    if field.name ~= is_set_name and field.type ~= 'OptionalKeys' then
+      table.insert(keys, dict_key)
+      if dict_key ~= field.name then
+        c_names[dict_key] = field.name
+      end
+    else
+      if i > 1 then
+        error("'is_set__{type}_' must be first if present")
+      elseif field.name ~= is_set_name then
+        error(val.keyset_name .. ': name of first key should be ' .. is_set_name)
+      elseif field.type ~= 'OptionalKeys' then
+        error("'" .. is_set_name .. "' must have type 'OptionalKeys'")
+      end
+      has_optional = true
+    end
+  end
+  table.insert(keysets, {
+    name = val.keyset_name,
+    keys = keys,
+    c_names = c_names,
+    types = types,
+    has_optional = has_optional,
+  })
+end
+
+local ui_options_text = nil
+
+-- read each input file, parse and append to the api metadata
+for i = pre_args + 1, #arg do
+  local full_path = arg[i]
+  local parts = {}
+  for part in string.gmatch(full_path, '[^/]+') do
+    parts[#parts + 1] = part
+  end
+  headers[#headers + 1] = parts[#parts - 1] .. '/' .. parts[#parts]
+
+  local input = assert(io.open(full_path, 'rb'))
+
+  local text = input:read('*all')
+  local tmp = c_grammar.grammar:match(text)
+  for j = 1, #tmp do
+    local val = tmp[j]
+    if val.keyset_name then
+      add_keyset(val)
+    elseif val.name then
+      add_function(val)
+    end
+  end
+
+  ui_options_text = ui_options_text or string.match(text, 'ui_ext_names%[][^{]+{([^}]+)}')
+  input:close()
+end
+
+local function shallowcopy(orig)
+  local copy = {}
+  for orig_key, orig_value in pairs(orig) do
+    copy[orig_key] = orig_value
+  end
+  return copy
+end
+
+-- Export functions under older deprecated names.
+-- These will be removed eventually.
+local deprecated_aliases = require('nvim.api.dispatch_deprecated')
+for _, f in ipairs(shallowcopy(functions)) do
+  local ismethod = false
+  if startswith(f.name, 'nvim_') then
+    if startswith(f.name, 'nvim__') or f.name == 'nvim_error_event' then
+      f.since = -1
+    elseif f.since == nil then
+      print('Function ' .. f.name .. ' lacks since field.\n')
+      os.exit(1)
+    end
+    f.since = tonumber(f.since)
+    if f.deprecated_since ~= nil then
+      f.deprecated_since = tonumber(f.deprecated_since)
+    end
+
+    if startswith(f.name, 'nvim_buf_') then
+      ismethod = true
+    elseif startswith(f.name, 'nvim_win_') then
+      ismethod = true
+    elseif startswith(f.name, 'nvim_tabpage_') then
+      ismethod = true
+    end
+    f.remote = f.remote_only or not f.lua_only
+    f.lua = f.lua_only or not f.remote_only
+    f.eval = (not f.lua_only) and not f.remote_only
+  else
+    f.deprecated_since = tonumber(f.deprecated_since)
+    assert(f.deprecated_since == 1)
+    f.remote = true
+    f.since = 0
+  end
+  f.method = ismethod
+  local newname = deprecated_aliases[f.name]
+  if newname ~= nil then
+    if function_names[newname] then
+      -- duplicate
+      print(
+        'Function '
+          .. f.name
+          .. ' has deprecated alias\n'
+          .. newname
+          .. ' which has a separate implementation.\n'
+          .. 'Please remove it from src/nvim/api/dispatch_deprecated.lua'
+      )
+      os.exit(1)
+    end
+    local newf = shallowcopy(f)
+    newf.name = newname
+    if newname == 'ui_try_resize' then
+      -- The return type was incorrectly set to Object in 0.1.5.
+      -- Keep it that way for clients that rely on this.
+      newf.return_type = 'Object'
+    end
+    newf.impl_name = f.name
+    newf.lua = false
+    newf.eval = false
+    newf.since = 0
+    newf.deprecated_since = 1
+    functions[#functions + 1] = newf
+  end
+end
+
+-- don't expose internal attributes like "impl_name" in public metadata
+local exported_attributes = { 'name', 'return_type', 'method', 'since', 'deprecated_since' }
+local exported_functions = {}
+for _, f in ipairs(functions) do
+  if not (startswith(f.name, 'nvim__') or f.name == 'nvim_error_event' or f.name == 'redraw') then
+    local f_exported = {}
+    for _, attr in ipairs(exported_attributes) do
+      f_exported[attr] = f[attr]
+    end
+    f_exported.parameters = {}
+    for i, param in ipairs(f.parameters) do
+      if param[1] == 'DictOf(LuaRef)' then
+        param = { 'Dict', param[2] }
+      elseif startswith(param[1], 'Dict(') then
+        param = { 'Dict', param[2] }
+      end
+      f_exported.parameters[i] = param
+    end
+    if startswith(f.return_type, 'Dict(') then
+      f_exported.return_type = 'Dict'
+    end
+    exported_functions[#exported_functions + 1] = f_exported
+  end
+end
+
+local ui_options = { 'rgb' }
+for x in string.gmatch(ui_options_text, '"([a-z][a-z_]+)"') do
+  table.insert(ui_options, x)
+end
+
+local version = require 'nvim_version' -- `build/nvim_version.lua` file.
+local git_version = io.open(git_version_inputf):read '*a'
+local version_build = string.match(git_version, '#define NVIM_VERSION_BUILD "([^"]+)"') or vim.NIL
+
+-- serialize the API metadata using msgpack and embed into the resulting
+-- binary for easy querying by clients
+local api_metadata_output = assert(io.open(api_metadata_outputf, 'wb'))
+local pieces = {}
+
+-- Naively using mpack.encode({foo=x, bar=y}) will make the build
+-- "non-reproducible". Emit maps directly as FIXDICT(2) "foo" x "bar" y instead
+local function fixdict(num)
+  if num > 15 then
+    error 'implement more dict codes'
+  end
+  table.insert(pieces, string.char(128 + num))
+end
+local function put(item, item2)
+  table.insert(pieces, mpack.encode(item))
+  if item2 ~= nil then
+    table.insert(pieces, mpack.encode(item2))
+  end
+end
+
+fixdict(6)
+
+put('version')
+fixdict(1 + #version)
+for _, item in ipairs(version) do
+  -- NB: all items are mandatory. But any error will be less confusing
+  -- with placeholder vim.NIL (than invalid mpack data)
+  local val = item[2] == nil and vim.NIL or item[2]
+  put(item[1], val)
+end
+put('build', version_build)
+
+put('functions', exported_functions)
+put('ui_events')
+table.insert(pieces, io.open(ui_metadata_inputf, 'rb'):read('*all'))
+put('ui_options', ui_options)
+
+put('error_types')
+fixdict(2)
+put('Exception', { id = 0 })
+put('Validation', { id = 1 })
+
+put('types')
+local types =
+  { { 'Buffer', 'nvim_buf_' }, { 'Window', 'nvim_win_' }, { 'Tabpage', 'nvim_tabpage_' } }
+fixdict(#types)
+for i, item in ipairs(types) do
+  put(item[1])
+  fixdict(2)
+  put('id', i - 1)
+  put('prefix', item[2])
+end
+
+local packed = table.concat(pieces)
+local dump_bin_array = require('gen.dump_bin_array')
+dump_bin_array(api_metadata_output, 'packed_api_metadata', packed)
+api_metadata_output:close()
+
+-- start building the dispatch wrapper output
+local output = assert(io.open(dispatch_outputf, 'wb'))
+
+local keysets_defs = assert(io.open(keysets_outputf, 'wb'))
+
+-- ===========================================================================
+-- NEW API FILES MUST GO HERE.
+--
+--  When creating a new API file, you must include it here,
+--  so that the dispatcher can find the C functions that you are creating!
+-- ===========================================================================
+output:write([[
+#include "nvim/errors.h"
+#include "nvim/ex_docmd.h"
+#include "nvim/ex_getln.h"
+#include "nvim/globals.h"
+#include "nvim/log.h"
+#include "nvim/map_defs.h"
+
+#include "nvim/api/autocmd.h"
+#include "nvim/api/buffer.h"
+#include "nvim/api/command.h"
+#include "nvim/api/deprecated.h"
+#include "nvim/api/extmark.h"
+#include "nvim/api/options.h"
+#include "nvim/api/tabpage.h"
+#include "nvim/api/ui.h"
+#include "nvim/api/vim.h"
+#include "nvim/api/vimscript.h"
+#include "nvim/api/win_config.h"
+#include "nvim/api/window.h"
+#include "nvim/ui_client.h"
+
+]])
+
+keysets_defs:write('// IWYU pragma: private, include "nvim/api/private/dispatch.h"\n\n')
+
+for _, k in ipairs(keysets) do
+  local neworder, hashfun = hashy.hashy_hash(k.name, k.keys, function(idx)
+    return k.name .. '_table[' .. idx .. '].str'
+  end)
+
+  keysets_defs:write('extern KeySetLink ' .. k.name .. '_table[' .. (1 + #neworder) .. '];\n')
+
+  local function typename(type)
+    if type == 'HLGroupID' then
+      return 'kObjectTypeInteger'
+    elseif not type or vim.startswith(type, 'Union') then
+      return 'kObjectTypeNil'
+    elseif vim.startswith(type, 'LuaRefOf') then
+      return 'kObjectTypeLuaRef'
+    elseif type == 'StringArray' then
+      return 'kUnpackTypeStringArray'
+    elseif vim.startswith(type, 'ArrayOf') then
+      return 'kObjectTypeArray'
+    else
+      return 'kObjectType' .. type
+    end
+  end
+
+  output:write('KeySetLink ' .. k.name .. '_table[] = {\n')
+  for i, key in ipairs(neworder) do
+    local ind = -1
+    if k.has_optional then
+      ind = i
+      keysets_defs:write('#define KEYSET_OPTIDX_' .. k.name .. '__' .. key .. ' ' .. ind .. '\n')
+    end
+    output:write(
+      '  {"'
+        .. key
+        .. '", offsetof(KeyDict_'
+        .. k.name
+        .. ', '
+        .. (k.c_names[key] or key)
+        .. '), '
+        .. typename(k.types[key])
+        .. ', '
+        .. ind
+        .. ', '
+        .. (k.types[key] == 'HLGroupID' and 'true' or 'false')
+        .. '},\n'
+    )
+  end
+  output:write('  {NULL, 0, kObjectTypeNil, -1, false},\n')
+  output:write('};\n\n')
+
+  output:write(hashfun)
+
+  output:write([[
+KeySetLink *KeyDict_]] .. k.name .. [[_get_field(const char *str, size_t len)
+{
+  int hash = ]] .. k.name .. [[_hash(str, len);
+  if (hash == -1) {
+    return NULL;
+  }
+  return &]] .. k.name .. [[_table[hash];
+}
+
+]])
+end
+
+local function real_type(type)
+  local rv = type
+  local rmatch = string.match(type, 'Dict%(([_%w]+)%)')
+  if rmatch then
+    return 'KeyDict_' .. rmatch
+  elseif c_grammar.typed_container:match(rv) then
+    if rv:match('Array') then
+      rv = 'Array'
+    else
+      rv = 'Dict'
+    end
+  end
+  return rv
+end
+
+local function attr_name(rt)
+  if rt == 'Float' then
+    return 'floating'
+  else
+    return rt:lower()
+  end
+end
+
+-- start the handler functions. Visit each function metadata to build the
+-- handler function with code generated for validating arguments and calling to
+-- the real API.
+for i = 1, #functions do
+  local fn = functions[i]
+  if fn.impl_name == nil and fn.remote then
+    local args = {}
+
+    output:write(
+      'Object handle_' .. fn.name .. '(uint64_t channel_id, Array args, Arena* arena, Error *error)'
+    )
+    output:write('\n{')
+    output:write('\n#ifdef NVIM_LOG_DEBUG')
+    output:write('\n  DLOG("RPC: ch %" PRIu64 ": invoke ' .. fn.name .. '", channel_id);')
+    output:write('\n#endif')
+    output:write('\n  Object ret = NIL;')
+    -- Declare/initialize variables that will hold converted arguments
+    for j = 1, #fn.parameters do
+      local param = fn.parameters[j]
+      local rt = real_type(param[1])
+      local converted = 'arg_' .. j
+      output:write('\n  ' .. rt .. ' ' .. converted .. ';')
+    end
+    output:write('\n')
+    if not fn.receives_array_args then
+      output:write('\n  if (args.size != ' .. #fn.parameters .. ') {')
+      output:write(
+        '\n    api_set_error(error, kErrorTypeException, \
+        "Wrong number of arguments: expecting '
+          .. #fn.parameters
+          .. ' but got %zu", args.size);'
+      )
+      output:write('\n    goto cleanup;')
+      output:write('\n  }\n')
+    end
+
+    -- Validation/conversion for each argument
+    for j = 1, #fn.parameters do
+      local converted, param
+      param = fn.parameters[j]
+      converted = 'arg_' .. j
+      local rt = real_type(param[1])
+      if rt == 'Object' then
+        output:write('\n  ' .. converted .. ' = args.items[' .. (j - 1) .. '];\n')
+      elseif rt:match('^KeyDict_') then
+        converted = '&' .. converted
+        output:write('\n  if (args.items[' .. (j - 1) .. '].type == kObjectTypeDict) {') --luacheck: ignore 631
+        output:write('\n    memset(' .. converted .. ', 0, sizeof(*' .. converted .. '));') -- TODO: neeeee
+        output:write(
+          '\n    if (!api_dict_to_keydict('
+            .. converted
+            .. ', '
+            .. rt
+            .. '_get_field, args.items['
+            .. (j - 1)
+            .. '].data.dict, error)) {'
+        )
+        output:write('\n      goto cleanup;')
+        output:write('\n    }')
+        output:write(
+          '\n  } else if (args.items['
+            .. (j - 1)
+            .. '].type == kObjectTypeArray && args.items['
+            .. (j - 1)
+            .. '].data.array.size == 0) {'
+        ) --luacheck: ignore 631
+        output:write('\n    memset(' .. converted .. ', 0, sizeof(*' .. converted .. '));')
+
+        output:write('\n  } else {')
+        output:write(
+          '\n    api_set_error(error, kErrorTypeException, \
+          "Wrong type for argument '
+            .. j
+            .. ' when calling '
+            .. fn.name
+            .. ', expecting '
+            .. param[1]
+            .. '");'
+        )
+        output:write('\n    goto cleanup;')
+        output:write('\n  }\n')
+      else
+        if rt:match('^Buffer$') or rt:match('^Window$') or rt:match('^Tabpage$') then
+          -- Buffer, Window, and Tabpage have a specific type, but are stored in integer
+          output:write(
+            '\n  if (args.items['
+              .. (j - 1)
+              .. '].type == kObjectType'
+              .. rt
+              .. ' && args.items['
+              .. (j - 1)
+              .. '].data.integer >= 0) {'
+          )
+          output:write(
+            '\n    ' .. converted .. ' = (handle_T)args.items[' .. (j - 1) .. '].data.integer;'
+          )
+        else
+          output:write('\n  if (args.items[' .. (j - 1) .. '].type == kObjectType' .. rt .. ') {')
+          output:write(
+            '\n    '
+              .. converted
+              .. ' = args.items['
+              .. (j - 1)
+              .. '].data.'
+              .. attr_name(rt)
+              .. ';'
+          )
+        end
+        if
+          rt:match('^Buffer$')
+          or rt:match('^Window$')
+          or rt:match('^Tabpage$')
+          or rt:match('^Boolean$')
+        then
+          -- accept nonnegative integers for Booleans, Buffers, Windows and Tabpages
+          output:write(
+            '\n  } else if (args.items['
+              .. (j - 1)
+              .. '].type == kObjectTypeInteger && args.items['
+              .. (j - 1)
+              .. '].data.integer >= 0) {'
+          )
+          output:write(
+            '\n    ' .. converted .. ' = (handle_T)args.items[' .. (j - 1) .. '].data.integer;'
+          )
+        end
+        if rt:match('^Float$') then
+          -- accept integers for Floats
+          output:write('\n  } else if (args.items[' .. (j - 1) .. '].type == kObjectTypeInteger) {')
+          output:write(
+            '\n    ' .. converted .. ' = (Float)args.items[' .. (j - 1) .. '].data.integer;'
+          )
+        end
+        -- accept empty lua tables as empty dictionaries
+        if rt:match('^Dict') then
+          output:write(
+            '\n  } else if (args.items['
+              .. (j - 1)
+              .. '].type == kObjectTypeArray && args.items['
+              .. (j - 1)
+              .. '].data.array.size == 0) {'
+          ) --luacheck: ignore 631
+          output:write('\n    ' .. converted .. ' = (Dict)ARRAY_DICT_INIT;')
+        end
+        output:write('\n  } else {')
+        output:write(
+          '\n    api_set_error(error, kErrorTypeException, \
+          "Wrong type for argument '
+            .. j
+            .. ' when calling '
+            .. fn.name
+            .. ', expecting '
+            .. param[1]
+            .. '");'
+        )
+        output:write('\n    goto cleanup;')
+        output:write('\n  }\n')
+      end
+      args[#args + 1] = converted
+    end
+
+    if fn.textlock then
+      output:write('\n  if (text_locked()) {')
+      output:write('\n    api_set_error(error, kErrorTypeException, "%s", get_text_locked_msg());')
+      output:write('\n    goto cleanup;')
+      output:write('\n  }\n')
+    elseif fn.textlock_allow_cmdwin then
+      output:write('\n  if (textlock != 0 || expr_map_locked()) {')
+      output:write('\n    api_set_error(error, kErrorTypeException, "%s", e_textlock);')
+      output:write('\n    goto cleanup;')
+      output:write('\n  }\n')
+    end
+
+    -- function call
+    output:write('\n  ')
+    if fn.return_type ~= 'void' then
+      -- has a return value, prefix the call with a declaration
+      output:write(fn.return_type .. ' rv = ')
+    end
+
+    -- write the function name and the opening parenthesis
+    output:write(fn.name .. '(')
+
+    local call_args = {}
+    if fn.receives_channel_id then
+      table.insert(call_args, 'channel_id')
+    end
+
+    if fn.receives_array_args then
+      table.insert(call_args, 'args')
+    end
+
+    for _, a in ipairs(args) do
+      table.insert(call_args, a)
+    end
+
+    if fn.receives_arena then
+      table.insert(call_args, 'arena')
+    end
+
+    if fn.has_lua_imp then
+      table.insert(call_args, 'NULL')
+    end
+
+    if fn.can_fail then
+      table.insert(call_args, 'error')
+    end
+
+    output:write(table.concat(call_args, ', '))
+    output:write(');\n')
+
+    if fn.can_fail then
+      -- if the function can fail, also pass a pointer to the local error object
+      -- and check for the error
+      output:write('\n  if (ERROR_SET(error)) {')
+      output:write('\n    goto cleanup;')
+      output:write('\n  }\n')
+    end
+
+    local ret_type = real_type(fn.return_type)
+    if string.match(ret_type, '^KeyDict_') then
+      local table = string.sub(ret_type, 9) .. '_table'
+      output:write(
+        '\n  ret = DICT_OBJ(api_keydict_to_dict(&rv, '
+          .. table
+          .. ', ARRAY_SIZE('
+          .. table
+          .. '), arena));'
+      )
+    elseif ret_type ~= 'void' then
+      output:write('\n  ret = ' .. string.upper(real_type(fn.return_type)) .. '_OBJ(rv);')
+    end
+    output:write('\n\ncleanup:')
+
+    output:write('\n  return ret;\n}\n\n')
+  end
+end
+
+local remote_fns = {}
+for _, fn in ipairs(functions) do
+  if fn.remote then
+    remote_fns[fn.name] = fn
+  end
+end
+remote_fns.redraw = { impl_name = 'ui_client_redraw', fast = true }
+
+local names = vim.tbl_keys(remote_fns)
+table.sort(names)
+local hashorder, hashfun = hashy.hashy_hash('msgpack_rpc_get_handler_for', names, function(idx)
+  return 'method_handlers[' .. idx .. '].name'
+end)
+
+output:write('const MsgpackRpcRequestHandler method_handlers[] = {\n')
+for n, name in ipairs(hashorder) do
+  local fn = remote_fns[name]
+  fn.handler_id = n - 1
+  output:write(
+    '  { .name = "'
+      .. name
+      .. '", .fn = handle_'
+      .. (fn.impl_name or fn.name)
+      .. ', .fast = '
+      .. tostring(fn.fast)
+      .. ', .ret_alloc = '
+      .. tostring(not not fn.ret_alloc)
+      .. '},\n'
+  )
+end
+output:write('};\n\n')
+output:write(hashfun)
+
+output:close()
+
+functions.keysets = keysets
+local mpack_output = assert(io.open(mpack_outputf, 'wb'))
+mpack_output:write(mpack.encode(functions))
+mpack_output:close()
+
+local function include_headers(output_handle, headers_to_include)
+  for i = 1, #headers_to_include do
+    if headers_to_include[i]:sub(-12) ~= '.generated.h' then
+      output_handle:write('\n#include "nvim/' .. headers_to_include[i] .. '"')
+    end
+  end
+end
+
+local function write_shifted_output(str, ...)
+  str = str:gsub('\n  ', '\n')
+  str = str:gsub('^  ', '')
+  str = str:gsub(' +$', '')
+  output:write(string.format(str, ...))
+end
+
+-- start building lua output
+output = assert(io.open(lua_c_bindings_outputf, 'wb'))
+
+include_headers(output, headers)
+output:write('\n')
+
+local lua_c_functions = {}
+
+local function process_function(fn)
+  local lua_c_function_name = ('nlua_api_%s'):format(fn.name)
+  write_shifted_output(
+    [[
+
+  static int %s(lua_State *lstate)
+  {
+    Error err = ERROR_INIT;
+    Arena arena = ARENA_EMPTY;
+    char *err_param = 0;
+    if (lua_gettop(lstate) != %i) {
+      api_set_error(&err, kErrorTypeValidation, "Expected %i argument%s");
+      goto exit_0;
+    }
+  ]],
+    lua_c_function_name,
+    #fn.parameters,
+    #fn.parameters,
+    (#fn.parameters == 1) and '' or 's'
+  )
+  lua_c_functions[#lua_c_functions + 1] = {
+    binding = lua_c_function_name,
+    api = fn.name,
+  }
+
+  if not fn.fast then
+    write_shifted_output(
+      [[
+    if (!nlua_is_deferred_safe()) {
+      return luaL_error(lstate, e_fast_api_disabled, "%s");
+    }
+    ]],
+      fn.name
+    )
+  end
+
+  if fn.textlock then
+    write_shifted_output([[
+    if (text_locked()) {
+      api_set_error(&err, kErrorTypeException, "%%s", get_text_locked_msg());
+      goto exit_0;
+    }
+    ]])
+  elseif fn.textlock_allow_cmdwin then
+    write_shifted_output([[
+    if (textlock != 0 || expr_map_locked()) {
+      api_set_error(&err, kErrorTypeException, "%%s", e_textlock);
+      goto exit_0;
+    }
+    ]])
+  end
+
+  local cparams = ''
+  local free_code = {}
+  for j = #fn.parameters, 1, -1 do
+    local param = fn.parameters[j]
+    local cparam = string.format('arg%u', j)
+    local param_type = real_type(param[1])
+    local extra = param_type == 'Dict' and 'false, ' or ''
+    local arg_free_code = ''
+    if param[1] == 'Object' then
+      extra = 'true, '
+      arg_free_code = '  api_luarefs_free_object(' .. cparam .. ');'
+    elseif param[1] == 'DictOf(LuaRef)' then
+      extra = 'true, '
+      arg_free_code = '  api_luarefs_free_dict(' .. cparam .. ');'
+    elseif param[1] == 'LuaRef' then
+      arg_free_code = '  api_free_luaref(' .. cparam .. ');'
+    end
+    local errshift = 0
+    local seterr = ''
+    if string.match(param_type, '^KeyDict_') then
+      write_shifted_output(
+        [[
+    %s %s = KEYDICT_INIT;
+    nlua_pop_keydict(lstate, &%s, %s_get_field, &err_param, &arena, &err);
+    ]],
+        param_type,
+        cparam,
+        cparam,
+        param_type
+      )
+      cparam = '&' .. cparam
+      errshift = 1 -- free incomplete dict on error
+      arg_free_code = '  api_luarefs_free_keydict('
+        .. cparam
+        .. ', '
+        .. string.sub(param_type, 9)
+        .. '_table);'
+    else
+      write_shifted_output(
+        [[
+    const %s %s = nlua_pop_%s(lstate, %s&arena, &err);]],
+        param[1],
+        cparam,
+        param_type,
+        extra
+      )
+      seterr = '\n      err_param = "' .. param[2] .. '";'
+    end
+
+    write_shifted_output([[
+
+    if (ERROR_SET(&err)) {]] .. seterr .. [[
+
+      goto exit_%u;
+    }
+
+    ]], #fn.parameters - j + errshift)
+    free_code[#free_code + 1] = arg_free_code
+    cparams = cparam .. ', ' .. cparams
+  end
+  if fn.receives_channel_id then
+    cparams = 'LUA_INTERNAL_CALL, ' .. cparams
+  end
+  if fn.receives_arena then
+    cparams = cparams .. '&arena, '
+  end
+
+  if fn.has_lua_imp then
+    cparams = cparams .. 'lstate, '
+  end
+
+  if fn.can_fail then
+    cparams = cparams .. '&err'
+  else
+    cparams = cparams:gsub(', $', '')
+  end
+  local free_at_exit_code = ''
+  for i = 1, #free_code do
+    local rev_i = #free_code - i + 1
+    local code = free_code[rev_i]
+    if i == 1 and not string.match(real_type(fn.parameters[1][1]), '^KeyDict_') then
+      free_at_exit_code = free_at_exit_code .. ('\n%s'):format(code)
+    else
+      free_at_exit_code = free_at_exit_code .. ('\nexit_%u:\n%s'):format(rev_i, code)
+    end
+  end
+  local err_throw_code = [[
+
+exit_0:
+  arena_mem_free(arena_finish(&arena));
+  if (ERROR_SET(&err)) {
+    luaL_where(lstate, 1);
+    if (err_param) {
+      lua_pushstring(lstate, "Invalid '");
+      lua_pushstring(lstate, err_param);
+      lua_pushstring(lstate, "': ");
+    }
+    lua_pushstring(lstate, err.msg);
+    api_clear_error(&err);
+    lua_concat(lstate, err_param ? 5 : 2);
+    return lua_error(lstate);
+  }
+]]
+  local return_type
+  if fn.return_type ~= 'void' then
+    if fn.return_type:match('^ArrayOf') then
+      return_type = 'Array'
+    else
+      return_type = fn.return_type
+    end
+    local free_retval = ''
+    if fn.ret_alloc then
+      free_retval = '  api_free_' .. return_type:lower() .. '(ret);'
+    end
+    write_shifted_output('    %s ret = %s(%s);\n', fn.return_type, fn.name, cparams)
+
+    local ret_type = real_type(fn.return_type)
+    local ret_mode = (ret_type == 'Object') and '&' or ''
+    if fn.has_lua_imp then
+      -- only push onto the Lua stack if we haven't already
+      write_shifted_output(
+        [[
+    if (lua_gettop(lstate) == 0) {
+      nlua_push_%s(lstate, %sret, kNluaPushSpecial | kNluaPushFreeRefs);
+    }
+      ]],
+        return_type,
+        ret_mode
+      )
+    elseif string.match(ret_type, '^KeyDict_') then
+      write_shifted_output(
+        '    nlua_push_keydict(lstate, &ret, %s_table);\n',
+        string.sub(ret_type, 9)
+      )
+    else
+      local special = (fn.since ~= nil and fn.since < 11)
+      write_shifted_output(
+        '    nlua_push_%s(lstate, %sret, %s | kNluaPushFreeRefs);\n',
+        return_type,
+        ret_mode,
+        special and 'kNluaPushSpecial' or '0'
+      )
+    end
+
+    -- NOTE: we currently assume err_throw needs nothing from arena
+    write_shifted_output(
+      [[
+  %s
+  %s
+  %s
+    return 1;
+    ]],
+      free_retval,
+      free_at_exit_code,
+      err_throw_code
+    )
+  else
+    write_shifted_output(
+      [[
+    %s(%s);
+  %s
+  %s
+    return 0;
+    ]],
+      fn.name,
+      cparams,
+      free_at_exit_code,
+      err_throw_code
+    )
+  end
+  write_shifted_output([[
+  }
+  ]])
+end
+
+for _, fn in ipairs(functions) do
+  if fn.lua or fn.name:sub(1, 4) == '_vim' then
+    process_function(fn)
+  end
+end
+
+output:write(string.format(
+  [[
+void nlua_add_api_functions(lua_State *lstate)
+{
+  lua_createtable(lstate, 0, %u);
+]],
+  #lua_c_functions
+))
+for _, func in ipairs(lua_c_functions) do
+  output:write(string.format(
+    [[
+
+  lua_pushcfunction(lstate, &%s);
+  lua_setfield(lstate, -2, "%s");]],
+    func.binding,
+    func.api
+  ))
+end
+output:write([[
+
+  lua_setfield(lstate, -2, "api");
+}
+]])
+
+output:close()
+keysets_defs:close()
diff --git a/src/gen/gen_api_ui_events.lua b/src/gen/gen_api_ui_events.lua
new file mode 100644
index 0000000000..8ba67dafff
--- /dev/null
+++ b/src/gen/gen_api_ui_events.lua
@@ -0,0 +1,219 @@
+local mpack = vim.mpack
+
+assert(#arg == 5)
+local input = io.open(arg[1], 'rb')
+local call_output = io.open(arg[2], 'wb')
+local remote_output = io.open(arg[3], 'wb')
+local metadata_output = io.open(arg[4], 'wb')
+local client_output = io.open(arg[5], 'wb')
+
+local c_grammar = require('gen.c_grammar')
+local events = c_grammar.grammar:match(input:read('*all'))
+
+local hashy = require 'gen.hashy'
+
+local function write_signature(output, ev, prefix, notype)
+  output:write('(' .. prefix)
+  if prefix == '' and #ev.parameters == 0 then
+    output:write('void')
+  end
+  for j = 1, #ev.parameters do
+    if j > 1 or prefix ~= '' then
+      output:write(', ')
+    end
+    local param = ev.parameters[j]
+    if not notype then
+      output:write(param[1] .. ' ')
+    end
+    output:write(param[2])
+  end
+  output:write(')')
+end
+
+local function write_arglist(output, ev)
+  if #ev.parameters == 0 then
+    return
+  end
+  output:write('  MAXSIZE_TEMP_ARRAY(args, ' .. #ev.parameters .. ');\n')
+  for j = 1, #ev.parameters do
+    local param = ev.parameters[j]
+    local kind = string.upper(param[1])
+    output:write('  ADD_C(args, ')
+    output:write(kind .. '_OBJ(' .. param[2] .. ')')
+    output:write(');\n')
+  end
+end
+
+local function call_ui_event_method(output, ev)
+  output:write('void ui_client_event_' .. ev.name .. '(Array args)\n{\n')
+
+  local hlattrs_args_count = 0
+  if #ev.parameters > 0 then
+    output:write('  if (args.size < ' .. #ev.parameters)
+    for j = 1, #ev.parameters do
+      local kind = ev.parameters[j][1]
+      if kind ~= 'Object' then
+        if kind == 'HlAttrs' then
+          kind = 'Dict'
+        end
+        output:write('\n      || args.items[' .. (j - 1) .. '].type != kObjectType' .. kind .. '')
+      end
+    end
+    output:write(') {\n')
+    output:write('    ELOG("Error handling ui event \'' .. ev.name .. '\'");\n')
+    output:write('    return;\n')
+    output:write('  }\n')
+  end
+
+  for j = 1, #ev.parameters do
+    local param = ev.parameters[j]
+    local kind = param[1]
+    output:write('  ' .. kind .. ' arg_' .. j .. ' = ')
+    if kind == 'HlAttrs' then
+      -- The first HlAttrs argument is rgb_attrs and second is cterm_attrs
+      output:write(
+        'ui_client_dict2hlattrs(args.items['
+          .. (j - 1)
+          .. '].data.dict, '
+          .. (hlattrs_args_count == 0 and 'true' or 'false')
+          .. ');\n'
+      )
+      hlattrs_args_count = hlattrs_args_count + 1
+    elseif kind == 'Object' then
+      output:write('args.items[' .. (j - 1) .. '];\n')
+    elseif kind == 'Window' then
+      output:write('(Window)args.items[' .. (j - 1) .. '].data.integer;\n')
+    else
+      output:write('args.items[' .. (j - 1) .. '].data.' .. string.lower(kind) .. ';\n')
+    end
+  end
+
+  output:write('  tui_' .. ev.name .. '(tui')
+  for j = 1, #ev.parameters do
+    output:write(', arg_' .. j)
+  end
+  output:write(');\n')
+
+  output:write('}\n\n')
+end
+
+events = vim.tbl_filter(function(ev)
+  return ev[1] ~= 'empty' and ev[1] ~= 'preproc'
+end, events)
+
+for i = 1, #events do
+  local ev = events[i]
+  assert(ev.return_type == 'void')
+
+  if ev.since == nil and not ev.noexport then
+    print('Ui event ' .. ev.name .. ' lacks since field.\n')
+    os.exit(1)
+  end
+  ev.since = tonumber(ev.since)
+
+  local args = #ev.parameters > 0 and 'args' or 'noargs'
+  if not ev.remote_only then
+    if not ev.remote_impl and not ev.noexport then
+      remote_output:write('void remote_ui_' .. ev.name)
+      write_signature(remote_output, ev, 'RemoteUI *ui')
+      remote_output:write('\n{\n')
+      write_arglist(remote_output, ev)
+      remote_output:write('  push_call(ui, "' .. ev.name .. '", ' .. args .. ');\n')
+      remote_output:write('}\n\n')
+    end
+  end
+
+  if not (ev.remote_only and ev.remote_impl) then
+    call_output:write('void ui_call_' .. ev.name)
+    write_signature(call_output, ev, '')
+    call_output:write('\n{\n')
+    if ev.remote_only then
+      -- Lua callbacks may emit other events or the same event again. Avoid the latter
+      -- by adding a recursion guard to each generated function that may call a Lua callback.
+      call_output:write('  static bool entered = false;\n')
+      call_output:write('  if (entered) {\n')
+      call_output:write('    return;\n')
+      call_output:write('  }\n')
+      call_output:write('  entered = true;\n')
+      write_arglist(call_output, ev)
+      call_output:write(('  ui_call_event("%s", %s, %s)'):format(ev.name, tostring(ev.fast), args))
+      call_output:write(';\n  entered = false;\n')
+    elseif ev.compositor_impl then
+      call_output:write('  ui_comp_' .. ev.name)
+      write_signature(call_output, ev, '', true)
+      call_output:write(';\n')
+      call_output:write('  UI_CALL')
+      write_signature(call_output, ev, '!ui->composed, ' .. ev.name .. ', ui', true)
+      call_output:write(';\n')
+    else
+      call_output:write('  UI_CALL')
+      write_signature(call_output, ev, 'true, ' .. ev.name .. ', ui', true)
+      call_output:write(';\n')
+    end
+    call_output:write('}\n\n')
+  end
+
+  if ev.compositor_impl then
+    call_output:write('void ui_composed_call_' .. ev.name)
+    write_signature(call_output, ev, '')
+    call_output:write('\n{\n')
+    call_output:write('  UI_CALL')
+    write_signature(call_output, ev, 'ui->composed, ' .. ev.name .. ', ui', true)
+    call_output:write(';\n')
+    call_output:write('}\n\n')
+  end
+
+  if (not ev.remote_only) and not ev.noexport and not ev.client_impl and not ev.client_ignore then
+    call_ui_event_method(client_output, ev)
+  end
+end
+
+local client_events = {}
+for _, ev in ipairs(events) do
+  if (not ev.noexport) and ((not ev.remote_only) or ev.client_impl) and not ev.client_ignore then
+    client_events[ev.name] = ev
+  end
+end
+
+local hashorder, hashfun = hashy.hashy_hash(
+  'ui_client_handler',
+  vim.tbl_keys(client_events),
+  function(idx)
+    return 'event_handlers[' .. idx .. '].name'
+  end
+)
+
+client_output:write('static const UIClientHandler event_handlers[] = {\n')
+
+for _, name in ipairs(hashorder) do
+  client_output:write('  { .name = "' .. name .. '", .fn = ui_client_event_' .. name .. '},\n')
+end
+
+client_output:write('\n};\n\n')
+client_output:write(hashfun)
+
+call_output:close()
+remote_output:close()
+client_output:close()
+
+-- don't expose internal attributes like "impl_name" in public metadata
+local exported_attributes = { 'name', 'parameters', 'since', 'deprecated_since' }
+local exported_events = {}
+for _, ev in ipairs(events) do
+  local ev_exported = {}
+  for _, attr in ipairs(exported_attributes) do
+    ev_exported[attr] = ev[attr]
+  end
+  for _, p in ipairs(ev_exported.parameters) do
+    if p[1] == 'HlAttrs' or p[1] == 'Dict' then
+      -- TODO(justinmk): for back-compat, but do clients actually look at this?
+      p[1] = 'Dictionary'
+    end
+  end
+  if not ev.noexport then
+    exported_events[#exported_events + 1] = ev_exported
+  end
+end
+
+metadata_output:write(mpack.encode(exported_events))
+metadata_output:close()
diff --git a/src/gen/gen_char_blob.lua b/src/gen/gen_char_blob.lua
new file mode 100644
index 0000000000..c40e0d6e82
--- /dev/null
+++ b/src/gen/gen_char_blob.lua
@@ -0,0 +1,96 @@
+if arg[1] == '--help' then
+  print('Usage:')
+  print('  ' .. arg[0] .. ' [-c] target source varname [source varname]...')
+  print('')
+  print('Generates C file with big uint8_t blob.')
+  print('Blob will be stored in a static const array named varname.')
+  os.exit()
+end
+
+-- Recognized options:
+--   -c   compile Lua bytecode
+local options = {}
+
+while true do
+  local opt = string.match(arg[1], '^-(%w)')
+  if not opt then
+    break
+  end
+
+  options[opt] = true
+  table.remove(arg, 1)
+end
+
+assert(#arg >= 3 and (#arg - 1) % 2 == 0)
+
+local target_file = arg[1] or error('Need a target file')
+local target = io.open(target_file, 'w')
+
+target:write('#include <stdint.h>\n\n')
+
+local index_items = {}
+
+local warn_on_missing_compiler = true
+local modnames = {}
+for argi = 2, #arg, 2 do
+  local source_file = arg[argi]
+  local modname = arg[argi + 1]
+  if modnames[modname] then
+    error(string.format('modname %q is already specified for file %q', modname, modnames[modname]))
+  end
+  modnames[modname] = source_file
+
+  local varname = string.gsub(modname, '%.', '_dot_') .. '_module'
+  target:write(('static const uint8_t %s[] = {\n'):format(varname))
+
+  local output
+  if options.c then
+    local luac = os.getenv('LUAC_PRG')
+    if luac and luac ~= '' then
+      output = io.popen(luac:format(source_file), 'r'):read('*a')
+    elseif warn_on_missing_compiler then
+      print('LUAC_PRG is missing, embedding raw source')
+      warn_on_missing_compiler = false
+    end
+  end
+
+  if not output then
+    local source = io.open(source_file, 'r')
+      or error(string.format("source_file %q doesn't exist", source_file))
+    output = source:read('*a')
+    source:close()
+  end
+
+  local num_bytes = 0
+  local MAX_NUM_BYTES = 15 -- 78 / 5: maximum number of bytes on one line
+  target:write(' ')
+
+  local increase_num_bytes
+  increase_num_bytes = function()
+    num_bytes = num_bytes + 1
+    if num_bytes == MAX_NUM_BYTES then
+      num_bytes = 0
+      target:write('\n ')
+    end
+  end
+
+  for i = 1, string.len(output) do
+    local byte = output:byte(i)
+    target:write(string.format(' %3u,', byte))
+    increase_num_bytes()
+  end
+
+  target:write('  0};\n')
+  if modname ~= '_' then
+    table.insert(
+      index_items,
+      '  { "' .. modname .. '", ' .. varname .. ', sizeof ' .. varname .. ' },\n\n'
+    )
+  end
+end
+
+target:write('static ModuleDef builtin_modules[] = {\n')
+target:write(table.concat(index_items))
+target:write('};\n')
+
+target:close()
diff --git a/src/gen/gen_declarations.lua b/src/gen/gen_declarations.lua
new file mode 100644
index 0000000000..582ac756b4
--- /dev/null
+++ b/src/gen/gen_declarations.lua
@@ -0,0 +1,186 @@
+local grammar = require('gen.c_grammar').grammar
+
+--- @param fname string
+--- @return string?
+local function read_file(fname)
+  local f = io.open(fname, 'r')
+  if not f then
+    return
+  end
+  local contents = f:read('*a')
+  f:close()
+  return contents
+end
+
+--- @param fname string
+--- @param contents string[]
+local function write_file(fname, contents)
+  local contents_s = table.concat(contents, '\n') .. '\n'
+  local fcontents = read_file(fname)
+  if fcontents == contents_s then
+    return
+  end
+  local f = assert(io.open(fname, 'w'))
+  f:write(contents_s)
+  f:close()
+end
+
+--- @param fname string
+--- @param non_static_fname string
+--- @return string? non_static
+local function add_iwyu_non_static(fname, non_static_fname)
+  if fname:find('.*/src/nvim/.*%.c$') then
+    -- Add an IWYU pragma comment if the corresponding .h file exists.
+    local header_fname = fname:sub(1, -3) .. '.h'
+    local header_f = io.open(header_fname, 'r')
+    if header_f then
+      header_f:close()
+      return (header_fname:gsub('.*/src/nvim/', 'nvim/'))
+    end
+  elseif non_static_fname:find('/include/api/private/dispatch_wrappers%.h%.generated%.h$') then
+    return 'nvim/api/private/dispatch.h'
+  elseif non_static_fname:find('/include/ui_events_call%.h%.generated%.h$') then
+    return 'nvim/ui.h'
+  elseif non_static_fname:find('/include/ui_events_client%.h%.generated%.h$') then
+    return 'nvim/ui_client.h'
+  elseif non_static_fname:find('/include/ui_events_remote%.h%.generated%.h$') then
+    return 'nvim/api/ui.h'
+  end
+end
+
+--- @param d string
+local function process_decl(d)
+  -- Comments are really handled by preprocessor, so the following is not
+  -- needed
+  d = d:gsub('/%*.-%*/', '')
+  d = d:gsub('//.-\n', '\n')
+  d = d:gsub('# .-\n', '')
+  d = d:gsub('\n', ' ')
+  d = d:gsub('%s+', ' ')
+  d = d:gsub(' ?%( ?', '(')
+  d = d:gsub(' ?, ?', ', ')
+  d = d:gsub(' ?(%*+) ?', ' %1')
+  d = d:gsub(' ?(FUNC_ATTR_)', ' %1')
+  d = d:gsub(' $', '')
+  d = d:gsub('^ ', '')
+  return d .. ';'
+end
+
+--- @param fname string
+--- @param text string
+--- @return string[] static
+--- @return string[] non_static
+--- @return boolean any_static
+local function gen_declarations(fname, text)
+  local non_static = {} --- @type string[]
+  local static = {} --- @type string[]
+
+  local neededfile = fname:match('[^/]+$')
+  local curfile = nil
+  local any_static = false
+  for _, node in ipairs(grammar:match(text)) do
+    if node[1] == 'preproc' then
+      curfile = node.content:match('^%a* %d+ "[^"]-/?([^"/]+)"') or curfile
+    elseif node[1] == 'proto' and curfile == neededfile then
+      local node_text = text:sub(node.pos, node.endpos - 1)
+      local declaration = process_decl(node_text)
+
+      if node.static then
+        if not any_static and declaration:find('FUNC_ATTR_') then
+          any_static = true
+        end
+        static[#static + 1] = declaration
+      else
+        non_static[#non_static + 1] = 'DLLEXPORT ' .. declaration
+      end
+    end
+  end
+
+  return static, non_static, any_static
+end
+
+local usage = [[
+Usage:
+
+    gen_declarations.lua definitions.c static.h non-static.h definitions.i
+
+Generates declarations for a C file definitions.c, putting declarations for
+static functions into static.h and declarations for non-static functions into
+non-static.h. File `definitions.i' should contain an already preprocessed
+version of definitions.c and it is the only one which is actually parsed,
+definitions.c is needed only to determine functions from which file out of all
+functions found in definitions.i are needed and to generate an IWYU comment.
+]]
+
+local function main()
+  local fname = arg[1]
+  local static_fname = arg[2]
+  local non_static_fname = arg[3]
+  local preproc_fname = arg[4]
+  local static_basename = arg[5]
+
+  if fname == '--help' or #arg < 5 then
+    print(usage)
+    os.exit()
+  end
+
+  local text = assert(read_file(preproc_fname))
+
+  local static_decls, non_static_decls, any_static = gen_declarations(fname, text)
+
+  local static = {} --- @type string[]
+  if fname:find('.*/src/nvim/.*%.h$') then
+    static[#static + 1] = ('// IWYU pragma: private, include "%s"'):format(
+      fname:gsub('.*/src/nvim/', 'nvim/')
+    )
+  end
+  vim.list_extend(static, {
+    '#define DEFINE_FUNC_ATTRIBUTES',
+    '#include "nvim/func_attr.h"',
+    '#undef DEFINE_FUNC_ATTRIBUTES',
+  })
+  vim.list_extend(static, static_decls)
+  vim.list_extend(static, {
+    '#define DEFINE_EMPTY_ATTRIBUTES',
+    '#include "nvim/func_attr.h"  // IWYU pragma: export',
+    '',
+  })
+
+  write_file(static_fname, static)
+
+  if any_static then
+    local orig_text = assert(read_file(fname))
+    local pat = '\n#%s?include%s+"' .. static_basename .. '"\n'
+    local pat_comment = '\n#%s?include%s+"' .. static_basename .. '"%s*//'
+    if not orig_text:find(pat) and not orig_text:find(pat_comment) then
+      error(('fail: missing include for %s in %s'):format(static_basename, fname))
+    end
+  end
+
+  if non_static_fname ~= 'SKIP' then
+    local non_static = {} --- @type string[]
+    local iwyu_non_static = add_iwyu_non_static(fname, non_static_fname)
+    if iwyu_non_static then
+      non_static[#non_static + 1] = ('// IWYU pragma: private, include "%s"'):format(
+        iwyu_non_static
+      )
+    end
+    vim.list_extend(non_static, {
+      '#define DEFINE_FUNC_ATTRIBUTES',
+      '#include "nvim/func_attr.h"',
+      '#undef DEFINE_FUNC_ATTRIBUTES',
+      '#ifndef DLLEXPORT',
+      '#  ifdef MSWIN',
+      '#    define DLLEXPORT __declspec(dllexport)',
+      '#  else',
+      '#    define DLLEXPORT',
+      '#  endif',
+      '#endif',
+    })
+    vim.list_extend(non_static, non_static_decls)
+    non_static[#non_static + 1] = '#include "nvim/func_attr.h"'
+    write_file(non_static_fname, non_static)
+  end
+end
+
+return main()
diff --git a/src/gen/gen_eval.lua b/src/gen/gen_eval.lua
new file mode 100644
index 0000000000..9d2f2f7523
--- /dev/null
+++ b/src/gen/gen_eval.lua
@@ -0,0 +1,112 @@
+local mpack = vim.mpack
+
+local autodir = arg[1]
+local metadata_file = arg[2]
+local funcs_file = arg[3]
+
+local funcsfname = autodir .. '/funcs.generated.h'
+
+--Will generate funcs.generated.h with definition of functions static const array.
+
+local hashy = require 'gen.hashy'
+
+local hashpipe = assert(io.open(funcsfname, 'wb'))
+
+hashpipe:write([[
+#include "nvim/arglist.h"
+#include "nvim/cmdexpand.h"
+#include "nvim/cmdhist.h"
+#include "nvim/digraph.h"
+#include "nvim/eval.h"
+#include "nvim/eval/buffer.h"
+#include "nvim/eval/deprecated.h"
+#include "nvim/eval/fs.h"
+#include "nvim/eval/funcs.h"
+#include "nvim/eval/typval.h"
+#include "nvim/eval/vars.h"
+#include "nvim/eval/window.h"
+#include "nvim/ex_docmd.h"
+#include "nvim/ex_getln.h"
+#include "nvim/fold.h"
+#include "nvim/getchar.h"
+#include "nvim/insexpand.h"
+#include "nvim/mapping.h"
+#include "nvim/match.h"
+#include "nvim/mbyte.h"
+#include "nvim/menu.h"
+#include "nvim/mouse.h"
+#include "nvim/move.h"
+#include "nvim/quickfix.h"
+#include "nvim/runtime.h"
+#include "nvim/search.h"
+#include "nvim/state.h"
+#include "nvim/strings.h"
+#include "nvim/sign.h"
+#include "nvim/testing.h"
+#include "nvim/undo.h"
+
+]])
+
+local funcs = require('nvim.eval').funcs
+for _, func in pairs(funcs) do
+  if func.float_func then
+    func.func = 'float_op_wrapper'
+    func.data = '{ .float_func = &' .. func.float_func .. ' }'
+  end
+end
+
+local metadata = mpack.decode(io.open(metadata_file, 'rb'):read('*all'))
+for _, fun in ipairs(metadata) do
+  if fun.eval then
+    funcs[fun.name] = {
+      args = #fun.parameters,
+      func = 'api_wrapper',
+      data = '{ .api_handler = &method_handlers[' .. fun.handler_id .. '] }',
+    }
+  end
+end
+
+local func_names = vim.tbl_filter(function(name)
+  return name:match('__%d*$') == nil
+end, vim.tbl_keys(funcs))
+
+table.sort(func_names)
+
+local funcsdata = assert(io.open(funcs_file, 'w'))
+funcsdata:write(mpack.encode(func_names))
+funcsdata:close()
+
+local neworder, hashfun = hashy.hashy_hash('find_internal_func', func_names, function(idx)
+  return 'functions[' .. idx .. '].name'
+end)
+
+hashpipe:write('static const EvalFuncDef functions[] = {\n')
+
+for _, name in ipairs(neworder) do
+  local def = funcs[name]
+  local args = def.args or 0
+  if type(args) == 'number' then
+    args = { args, args }
+  elseif #args == 1 then
+    args[2] = 'MAX_FUNC_ARGS'
+  end
+  local base = def.base or 'BASE_NONE'
+  local func = def.func or ('f_' .. name)
+  local data = def.data or '{ .null = NULL }'
+  local fast = def.fast and 'true' or 'false'
+  hashpipe:write(
+    ('  { "%s", %s, %s, %s, %s, &%s, %s },\n'):format(
+      name,
+      args[1],
+      args[2],
+      base,
+      fast,
+      func,
+      data
+    )
+  )
+end
+hashpipe:write('  { NULL, 0, 0, BASE_NONE, false, NULL, { .null = NULL } },\n')
+hashpipe:write('};\n\n')
+hashpipe:write(hashfun)
+hashpipe:close()
diff --git a/src/gen/gen_eval_files.lua b/src/gen/gen_eval_files.lua
new file mode 100755
index 0000000000..74e45507e5
--- /dev/null
+++ b/src/gen/gen_eval_files.lua
@@ -0,0 +1,1090 @@
+#!/usr/bin/env -S nvim -l
+
+-- Generator for various vimdoc and Lua type files
+
+local util = require('gen.util')
+local fmt = string.format
+
+local DEP_API_METADATA = 'build/funcs_metadata.mpack'
+local TEXT_WIDTH = 78
+
+--- @class vim.api.metadata
+--- @field name string
+--- @field parameters [string,string][]
+--- @field return_type string
+--- @field deprecated_since integer
+--- @field eval boolean
+--- @field fast boolean
+--- @field handler_id integer
+--- @field impl_name string
+--- @field lua boolean
+--- @field method boolean
+--- @field remote boolean
+--- @field since integer
+
+local LUA_API_RETURN_OVERRIDES = {
+  nvim_buf_get_command = 'table<string,vim.api.keyset.command_info>',
+  nvim_buf_get_extmark_by_id = 'vim.api.keyset.get_extmark_item_by_id',
+  nvim_buf_get_extmarks = 'vim.api.keyset.get_extmark_item[]',
+  nvim_buf_get_keymap = 'vim.api.keyset.get_keymap[]',
+  nvim_get_autocmds = 'vim.api.keyset.get_autocmds.ret[]',
+  nvim_get_color_map = 'table<string,integer>',
+  nvim_get_command = 'table<string,vim.api.keyset.command_info>',
+  nvim_get_keymap = 'vim.api.keyset.get_keymap[]',
+  nvim_get_mark = 'vim.api.keyset.get_mark',
+
+  -- Can also return table<string,vim.api.keyset.get_hl_info>, however we need to
+  -- pick one to get some benefit.
+  -- REVISIT lewrus01 (26/01/24): we can maybe add
+  -- @overload fun(ns: integer, {}): table<string,vim.api.keyset.get_hl_info>
+  nvim_get_hl = 'vim.api.keyset.get_hl_info',
+
+  nvim_get_mode = 'vim.api.keyset.get_mode',
+  nvim_get_namespaces = 'table<string,integer>',
+  nvim_get_option_info = 'vim.api.keyset.get_option_info',
+  nvim_get_option_info2 = 'vim.api.keyset.get_option_info',
+  nvim_parse_cmd = 'vim.api.keyset.parse_cmd',
+  nvim_win_get_config = 'vim.api.keyset.win_config',
+}
+
+local LUA_API_KEYSET_OVERRIDES = {
+  create_autocmd = {
+    callback = 'string|(fun(args: vim.api.keyset.create_autocmd.callback_args): boolean?)',
+  },
+}
+
+local LUA_API_PARAM_OVERRIDES = {
+  nvim_create_user_command = {
+    command = 'string|fun(args: vim.api.keyset.create_user_command.command_args)',
+  },
+}
+
+local LUA_META_HEADER = {
+  '--- @meta _',
+  '-- THIS FILE IS GENERATED',
+  '-- DO NOT EDIT',
+  "error('Cannot require a meta file')",
+}
+
+local LUA_API_META_HEADER = {
+  '--- @meta _',
+  '-- THIS FILE IS GENERATED',
+  '-- DO NOT EDIT',
+  "error('Cannot require a meta file')",
+  '',
+  '--- This file embeds vimdoc as the function descriptions',
+  '--- so ignore any doc related errors.',
+  '--- @diagnostic disable: undefined-doc-name,luadoc-miss-symbol',
+  '',
+  'vim.api = {}',
+}
+
+local LUA_OPTION_META_HEADER = {
+  '--- @meta _',
+  '-- THIS FILE IS GENERATED',
+  '-- DO NOT EDIT',
+  "error('Cannot require a meta file')",
+  '',
+  '---@class vim.bo',
+  '---@field [integer] vim.bo',
+  'vim.bo = vim.bo',
+  '',
+  '---@class vim.wo',
+  '---@field [integer] vim.wo',
+  'vim.wo = vim.wo',
+}
+
+local LUA_VVAR_META_HEADER = {
+  '--- @meta _',
+  '-- THIS FILE IS GENERATED',
+  '-- DO NOT EDIT',
+  "error('Cannot require a meta file')",
+  '',
+  '--- @class vim.v',
+  'vim.v = ...',
+}
+
+local LUA_KEYWORDS = {
+  ['and'] = true,
+  ['end'] = true,
+  ['function'] = true,
+  ['or'] = true,
+  ['if'] = true,
+  ['while'] = true,
+  ['repeat'] = true,
+  ['true'] = true,
+  ['false'] = true,
+}
+
+local OPTION_TYPES = {
+  boolean = 'boolean',
+  number = 'integer',
+  string = 'string',
+}
+
+local API_TYPES = {
+  Window = 'integer',
+  Tabpage = 'integer',
+  Buffer = 'integer',
+  Boolean = 'boolean',
+  Object = 'any',
+  Integer = 'integer',
+  String = 'string',
+  Array = 'any[]',
+  LuaRef = 'function',
+  Dict = 'table<string,any>',
+  Float = 'number',
+  HLGroupID = 'integer|string',
+  void = '',
+}
+
+--- @param s string
+--- @return string
+local function luaescape(s)
+  if LUA_KEYWORDS[s] then
+    return s .. '_'
+  end
+  return s
+end
+
+--- @param x string
+--- @param sep? string
+--- @return string[]
+local function split(x, sep)
+  return vim.split(x, sep or '\n', { plain = true })
+end
+
+--- Convert an API type to Lua
+--- @param t string
+--- @return string
+local function api_type(t)
+  if vim.startswith(t, '*') then
+    return api_type(t:sub(2)) .. '?'
+  end
+
+  local as0 = t:match('^ArrayOf%((.*)%)')
+  if as0 then
+    local as = split(as0, ', ')
+    return api_type(as[1]) .. '[]'
+  end
+
+  local d = t:match('^Dict%((.*)%)')
+  if d then
+    return 'vim.api.keyset.' .. d
+  end
+
+  local d0 = t:match('^DictOf%((.*)%)')
+  if d0 then
+    return 'table<string,' .. api_type(d0) .. '>'
+  end
+
+  local u = t:match('^Union%((.*)%)')
+  if u then
+    local us = vim.split(u, ',%s*')
+    return table.concat(vim.tbl_map(api_type, us), '|')
+  end
+
+  local l = t:match('^LuaRefOf%((.*)%)')
+  if l then
+    --- @type string
+    l = l:gsub('%s+', ' ')
+    --- @type string?, string?
+    local as, r = l:match('%((.*)%),%s*(.*)')
+    if not as then
+      --- @type string
+      as = assert(l:match('%((.*)%)'))
+    end
+
+    local as1 = {} --- @type string[]
+    for a in vim.gsplit(as, ',%s') do
+      local a1 = vim.split(a, '%s+', { trimempty = true })
+      local nm = a1[2]:gsub('%*(.*)$', '%1?')
+      as1[#as1 + 1] = nm .. ': ' .. api_type(a1[1])
+    end
+
+    return ('fun(%s)%s'):format(table.concat(as1, ', '), r and ': ' .. api_type(r) or '')
+  end
+
+  return API_TYPES[t] or t
+end
+
+--- @param f string
+--- @param params [string,string][]|true
+--- @return string
+local function render_fun_sig(f, params)
+  local param_str --- @type string
+  if params == true then
+    param_str = '...'
+  else
+    param_str = table.concat(
+      vim.tbl_map(
+        --- @param v [string,string]
+        --- @return string
+        function(v)
+          return luaescape(v[1])
+        end,
+        params
+      ),
+      ', '
+    )
+  end
+
+  if LUA_KEYWORDS[f] then
+    return fmt("vim.fn['%s'] = function(%s) end", f, param_str)
+  else
+    return fmt('function vim.fn.%s(%s) end', f, param_str)
+  end
+end
+
+--- Uniquify names
+--- @param params [string,string,string][]
+--- @return [string,string,string][]
+local function process_params(params)
+  local seen = {} --- @type table<string,true>
+  local sfx = 1
+
+  for _, p in ipairs(params) do
+    if seen[p[1]] then
+      p[1] = p[1] .. sfx
+      sfx = sfx + 1
+    else
+      seen[p[1]] = true
+    end
+  end
+
+  return params
+end
+
+--- @return table<string, vim.EvalFn>
+local function get_api_meta()
+  local ret = {} --- @type table<string, vim.EvalFn>
+
+  local cdoc_parser = require('gen.cdoc_parser')
+
+  local f = 'src/nvim/api'
+
+  local function include(fun)
+    if not vim.startswith(fun.name, 'nvim_') then
+      return false
+    end
+    if vim.tbl_contains(fun.attrs or {}, 'lua_only') then
+      return true
+    end
+    if vim.tbl_contains(fun.attrs or {}, 'remote_only') then
+      return false
+    end
+    return true
+  end
+
+  --- @type table<string,nvim.cdoc.parser.fun>
+  local functions = {}
+  for path, ty in vim.fs.dir(f) do
+    if ty == 'file' then
+      local filename = vim.fs.joinpath(f, path)
+      local _, funs = cdoc_parser.parse(filename)
+      for _, fn in ipairs(funs) do
+        if include(fn) then
+          functions[fn.name] = fn
+        end
+      end
+    end
+  end
+
+  for _, fun in pairs(functions) do
+    local deprecated = fun.deprecated_since ~= nil
+
+    local notes = {} --- @type string[]
+    for _, note in ipairs(fun.notes or {}) do
+      notes[#notes + 1] = note.desc
+    end
+
+    local sees = {} --- @type string[]
+    for _, see in ipairs(fun.see or {}) do
+      sees[#sees + 1] = see.desc
+    end
+
+    local pty_overrides = LUA_API_PARAM_OVERRIDES[fun.name] or {}
+
+    local params = {} --- @type [string,string][]
+    for _, p in ipairs(fun.params) do
+      params[#params + 1] = {
+        p.name,
+        api_type(pty_overrides[p.name] or p.type),
+        not deprecated and p.desc or nil,
+      }
+    end
+
+    local r = {
+      signature = 'NA',
+      name = fun.name,
+      params = params,
+      notes = notes,
+      see = sees,
+      returns = api_type(fun.returns[1].type),
+      deprecated = deprecated,
+    }
+
+    if not deprecated then
+      r.desc = fun.desc
+      r.returns_desc = fun.returns[1].desc
+    end
+
+    ret[fun.name] = r
+  end
+  return ret
+end
+
+--- Convert vimdoc references to markdown literals
+--- Convert vimdoc codeblocks to markdown codeblocks
+---
+--- Ensure code blocks have one empty line before the start fence and after the closing fence.
+---
+--- @param x string
+--- @param special string?
+---                | 'see-api-meta' Normalize `@see` for API meta docstrings.
+--- @return string
+local function norm_text(x, special)
+  if special == 'see-api-meta' then
+    -- Try to guess a symbol that actually works in @see.
+    -- "nvim_xx()" => "vim.api.nvim_xx"
+    x = x:gsub([=[%|?(nvim_[^.()| ]+)%(?%)?%|?]=], 'vim.api.%1')
+    -- TODO: Remove backticks when LuaLS resolves: https://github.com/LuaLS/lua-language-server/issues/2889
+    -- "|foo|" => "`:help foo`"
+    x = x:gsub([=[|([^ ]+)|]=], '`:help %1`')
+  end
+
+  return (
+    x:gsub('|([^ ]+)|', '`%1`')
+      :gsub('\n*>lua', '\n\n```lua')
+      :gsub('\n*>vim', '\n\n```vim')
+      :gsub('\n+<$', '\n```')
+      :gsub('\n+<\n+', '\n```\n\n')
+      :gsub('%s+>\n+', '\n```\n')
+      :gsub('\n+<%s+\n?', '\n```\n')
+  )
+end
+
+--- Generates LuaLS docstring for an API function.
+--- @param _f string
+--- @param fun vim.EvalFn
+--- @param write fun(line: string)
+local function render_api_meta(_f, fun, write)
+  write('')
+
+  if vim.startswith(fun.name, 'nvim__') then
+    write('--- @private')
+  end
+
+  if fun.deprecated then
+    write('--- @deprecated')
+  end
+
+  local desc = fun.desc
+  if desc then
+    write(util.prefix_lines('--- ', norm_text(desc)))
+  end
+
+  -- LuaLS doesn't support @note. Render @note items as a markdown list.
+  if fun.notes and #fun.notes > 0 then
+    write('--- Note:')
+    write(util.prefix_lines('--- ', table.concat(fun.notes, '\n')))
+    write('---')
+  end
+
+  for _, see in ipairs(fun.see or {}) do
+    write(util.prefix_lines('--- @see ', norm_text(see, 'see-api-meta')))
+  end
+
+  local param_names = {} --- @type string[]
+  local params = process_params(fun.params)
+  for _, p in ipairs(params) do
+    local pname, ptype, pdesc = luaescape(p[1]), p[2], p[3]
+    param_names[#param_names + 1] = pname
+    if pdesc then
+      local s = '--- @param ' .. pname .. ' ' .. ptype .. ' '
+      local pdesc_a = split(vim.trim(norm_text(pdesc)))
+      write(s .. pdesc_a[1])
+      for i = 2, #pdesc_a do
+        if not pdesc_a[i] then
+          break
+        end
+        write('--- ' .. pdesc_a[i])
+      end
+    else
+      write('--- @param ' .. pname .. ' ' .. ptype)
+    end
+  end
+
+  if fun.returns ~= '' then
+    local ret_desc = fun.returns_desc and ' # ' .. fun.returns_desc or ''
+    local ret = LUA_API_RETURN_OVERRIDES[fun.name] or fun.returns
+    write(util.prefix_lines('--- ', '@return ' .. ret .. ret_desc))
+  end
+  local param_str = table.concat(param_names, ', ')
+
+  write(fmt('function vim.api.%s(%s) end', fun.name, param_str))
+end
+
+--- @return table<string, vim.EvalFn>
+local function get_api_keysets_meta()
+  local mpack_f = assert(io.open(DEP_API_METADATA, 'rb'))
+  local metadata = assert(vim.mpack.decode(mpack_f:read('*all')))
+
+  local ret = {} --- @type table<string, vim.EvalFn>
+
+  --- @type {name: string, keys: string[], types: table<string,string>}[]
+  local keysets = metadata.keysets
+
+  for _, k in ipairs(keysets) do
+    local pty_overrides = LUA_API_KEYSET_OVERRIDES[k.name] or {}
+    local params = {}
+    for _, key in ipairs(k.keys) do
+      local pty = pty_overrides[key] or k.types[key] or 'any'
+      table.insert(params, { key .. '?', api_type(pty) })
+    end
+    ret[k.name] = {
+      signature = 'NA',
+      name = k.name,
+      params = params,
+    }
+  end
+
+  return ret
+end
+
+--- Generates LuaLS docstring for an API keyset.
+--- @param _f string
+--- @param fun vim.EvalFn
+--- @param write fun(line: string)
+local function render_api_keyset_meta(_f, fun, write)
+  if string.sub(fun.name, 1, 1) == '_' then
+    return -- not exported
+  end
+  write('')
+  write('--- @class vim.api.keyset.' .. fun.name)
+  for _, p in ipairs(fun.params) do
+    write('--- @field ' .. p[1] .. ' ' .. p[2])
+  end
+end
+
+--- @return table<string, vim.EvalFn>
+local function get_eval_meta()
+  return require('nvim.eval').funcs
+end
+
+--- Generates LuaLS docstring for a Vimscript "eval" function.
+--- @param f string
+--- @param fun vim.EvalFn
+--- @param write fun(line: string)
+local function render_eval_meta(f, fun, write)
+  if fun.lua == false then
+    return
+  end
+
+  local funname = fun.name or f
+  local params = process_params(fun.params)
+
+  write('')
+  if fun.deprecated then
+    write('--- @deprecated')
+  end
+
+  local desc = fun.desc
+
+  if desc then
+    --- @type string
+    desc = desc:gsub('\n%s*\n%s*$', '\n')
+    for _, l in ipairs(split(desc)) do
+      l = l:gsub('^      ', ''):gsub('\t', '  '):gsub('@', '\\@')
+      write('--- ' .. l)
+    end
+  end
+
+  for _, text in ipairs(vim.fn.reverse(fun.generics or {})) do
+    write(fmt('--- @generic %s', text))
+  end
+
+  local req_args = type(fun.args) == 'table' and fun.args[1] or fun.args or 0
+
+  for i, param in ipairs(params) do
+    local pname, ptype = luaescape(param[1]), param[2]
+    local optional = (pname ~= '...' and i > req_args) and '?' or ''
+    write(fmt('--- @param %s%s %s', pname, optional, ptype))
+  end
+
+  if fun.returns ~= false then
+    local ret_desc = fun.returns_desc and ' # ' .. fun.returns_desc or ''
+    write('--- @return ' .. (fun.returns or 'any') .. ret_desc)
+  end
+
+  write(render_fun_sig(funname, params))
+end
+
+--- Generates vimdoc heading for a Vimscript "eval" function signature.
+--- @param name string
+--- @param name_tag boolean
+--- @param fun vim.EvalFn
+--- @param write fun(line: string)
+local function render_sig_and_tag(name, name_tag, fun, write)
+  if not fun.signature then
+    return
+  end
+
+  local tags = name_tag and { '*' .. name .. '()*' } or {}
+
+  if fun.tags then
+    for _, t in ipairs(fun.tags) do
+      tags[#tags + 1] = '*' .. t .. '*'
+    end
+  end
+
+  if #tags == 0 then
+    write(fun.signature)
+    return
+  end
+
+  local tag = table.concat(tags, ' ')
+  local siglen = #fun.signature
+  local conceal_offset = 2 * (#tags - 1)
+  local tag_pad_len = math.max(1, 80 - #tag + conceal_offset)
+
+  if siglen + #tag > 80 then
+    write(string.rep(' ', tag_pad_len) .. tag)
+    write(fun.signature)
+  else
+    write(fmt('%s%s%s', fun.signature, string.rep(' ', tag_pad_len - siglen), tag))
+  end
+end
+
+--- Generates vimdoc for a Vimscript "eval" function.
+--- @param f string
+--- @param fun vim.EvalFn
+--- @param write fun(line: string)
+local function render_eval_doc(f, fun, write)
+  if fun.deprecated or not fun.signature then
+    return
+  end
+
+  render_sig_and_tag(fun.name or f, not f:find('__%d+$'), fun, write)
+
+  if not fun.desc then
+    return
+  end
+
+  local params = process_params(fun.params)
+  local req_args = type(fun.args) == 'table' and fun.args[1] or fun.args or 0
+
+  local desc_l = split(vim.trim(fun.desc))
+  for _, l in ipairs(desc_l) do
+    l = l:gsub('^      ', '')
+    if vim.startswith(l, '<') and not l:match('^<[^ \t]+>') then
+      write('<\t\t' .. l:sub(2))
+    elseif l:match('^>[a-z0-9]*$') then
+      write(l)
+    else
+      write('\t\t' .. l)
+    end
+  end
+
+  if #desc_l > 0 and not desc_l[#desc_l]:match('^<?$') then
+    write('')
+  end
+
+  if #params > 0 then
+    write(util.md_to_vimdoc('Parameters: ~', 16, 16, TEXT_WIDTH))
+    for i, param in ipairs(params) do
+      local pname, ptype = param[1], param[2]
+      local optional = (pname ~= '...' and i > req_args) and '?' or ''
+      local s = fmt('- %-14s (`%s%s`)', fmt('{%s}', pname), ptype, optional)
+      write(util.md_to_vimdoc(s, 16, 18, TEXT_WIDTH))
+    end
+    write('')
+  end
+
+  if fun.returns ~= false then
+    write(util.md_to_vimdoc('Return: ~', 16, 16, TEXT_WIDTH))
+    local ret = ('(`%s`)'):format((fun.returns or 'any'))
+    ret = ret .. (fun.returns_desc and ' ' .. fun.returns_desc or '')
+    ret = util.md_to_vimdoc(ret, 18, 18, TEXT_WIDTH)
+    write(ret)
+    write('')
+  end
+end
+
+--- @param d vim.option_defaults
+--- @param vimdoc? boolean
+--- @return string
+local function render_option_default(d, vimdoc)
+  local dt --- @type integer|boolean|string|fun(): string
+  if d.if_false ~= nil then
+    dt = d.if_false
+  else
+    dt = d.if_true
+  end
+
+  if vimdoc then
+    if d.doc then
+      return d.doc
+    end
+    if type(dt) == 'boolean' then
+      return dt and 'on' or 'off'
+    end
+  end
+
+  if dt == '' or dt == nil or type(dt) == 'function' then
+    dt = d.meta
+  end
+
+  local v --- @type string
+  if not vimdoc then
+    v = vim.inspect(dt) --[[@as string]]
+  else
+    v = type(dt) == 'string' and '"' .. dt .. '"' or tostring(dt)
+  end
+
+  --- @type table<string, string|false>
+  local envvars = {
+    TMPDIR = false,
+    VIMRUNTIME = false,
+    XDG_CONFIG_HOME = vim.env.HOME .. '/.local/config',
+    XDG_DATA_HOME = vim.env.HOME .. '/.local/share',
+    XDG_STATE_HOME = vim.env.HOME .. '/.local/state',
+  }
+
+  for name, default in pairs(envvars) do
+    local value = vim.env[name] or default
+    if value then
+      v = v:gsub(vim.pesc(value), '$' .. name)
+    end
+  end
+
+  return v
+end
+
+--- @param _f string
+--- @param opt vim.option_meta
+--- @param write fun(line: string)
+local function render_option_meta(_f, opt, write)
+  write('')
+  for _, l in ipairs(split(norm_text(opt.desc))) do
+    write('--- ' .. l)
+  end
+
+  if opt.type == 'string' and not opt.list and opt.values then
+    local values = {} --- @type string[]
+    for _, e in ipairs(opt.values) do
+      values[#values + 1] = fmt("'%s'", e)
+    end
+    write('--- @type ' .. table.concat(values, '|'))
+  else
+    write('--- @type ' .. OPTION_TYPES[opt.type])
+  end
+
+  write('vim.o.' .. opt.full_name .. ' = ' .. render_option_default(opt.defaults))
+  if opt.abbreviation then
+    write('vim.o.' .. opt.abbreviation .. ' = vim.o.' .. opt.full_name)
+  end
+
+  for _, s in pairs {
+    { 'wo', 'win' },
+    { 'bo', 'buf' },
+    { 'go', 'global' },
+  } do
+    local id, scope = s[1], s[2]
+    if vim.list_contains(opt.scope, scope) or (id == 'go' and #opt.scope > 1) then
+      local pfx = 'vim.' .. id .. '.'
+      write(pfx .. opt.full_name .. ' = vim.o.' .. opt.full_name)
+      if opt.abbreviation then
+        write(pfx .. opt.abbreviation .. ' = ' .. pfx .. opt.full_name)
+      end
+    end
+  end
+end
+
+--- @param _f string
+--- @param opt vim.option_meta
+--- @param write fun(line: string)
+local function render_vvar_meta(_f, opt, write)
+  write('')
+
+  local desc = split(norm_text(opt.desc))
+  while desc[#desc]:match('^%s*$') do
+    desc[#desc] = nil
+  end
+
+  for _, l in ipairs(desc) do
+    write('--- ' .. l)
+  end
+
+  write('--- @type ' .. (opt.type or 'any'))
+
+  if LUA_KEYWORDS[opt.full_name] then
+    write("vim.v['" .. opt.full_name .. "'] = ...")
+  else
+    write('vim.v.' .. opt.full_name .. ' = ...')
+  end
+end
+
+--- @param s string[]
+--- @return string
+local function scope_to_doc(s)
+  local m = {
+    global = 'global',
+    buf = 'local to buffer',
+    win = 'local to window',
+    tab = 'local to tab page',
+  }
+
+  if #s == 1 then
+    return m[s[1]]
+  end
+  assert(s[1] == 'global')
+  return 'global or ' .. m[s[2]] .. (s[2] ~= 'tab' and ' |global-local|' or '')
+end
+
+-- @param o vim.option_meta
+-- @return string
+local function scope_more_doc(o)
+  if
+    vim.list_contains({
+      'bufhidden',
+      'buftype',
+      'filetype',
+      'modified',
+      'previewwindow',
+      'readonly',
+      'scroll',
+      'syntax',
+      'winfixheight',
+      'winfixwidth',
+    }, o.full_name)
+  then
+    return '  |local-noglobal|'
+  end
+
+  return ''
+end
+
+--- @param x string
+--- @return string
+local function dedent(x)
+  local xs = split(x)
+  local leading_ws = xs[1]:match('^%s*') --[[@as string]]
+  local leading_ws_pat = '^' .. leading_ws
+
+  for i in ipairs(xs) do
+    local strip_pat = xs[i]:match(leading_ws_pat) and leading_ws_pat or '^%s*'
+    xs[i] = xs[i]:gsub(strip_pat, '')
+  end
+
+  return table.concat(xs, '\n')
+end
+
+--- @return table<string,vim.option_meta>
+local function get_option_meta()
+  local opts = require('nvim.options').options
+  local optinfo = vim.api.nvim_get_all_options_info()
+  local ret = {} --- @type table<string,vim.option_meta>
+  for _, o in ipairs(opts) do
+    local is_window_option = #o.scope == 1 and o.scope[1] == 'win'
+    local is_option_hidden = o.immutable and not o.varname and not is_window_option
+    if not is_option_hidden and o.desc then
+      if o.full_name == 'cmdheight' then
+        table.insert(o.scope, 'tab')
+      end
+      local r = vim.deepcopy(o) --[[@as vim.option_meta]]
+      r.desc = o.desc:gsub('^        ', ''):gsub('\n        ', '\n')
+      r.defaults = r.defaults or {}
+      if r.defaults.meta == nil then
+        r.defaults.meta = optinfo[o.full_name].default
+      end
+      ret[o.full_name] = r
+    end
+  end
+  return ret
+end
+
+--- @return table<string,vim.option_meta>
+local function get_vvar_meta()
+  local info = require('nvim.vvars').vars
+  local ret = {} --- @type table<string,vim.option_meta>
+  for name, o in pairs(info) do
+    o.desc = dedent(o.desc)
+    o.full_name = name
+    ret[name] = o
+  end
+  return ret
+end
+
+--- @param opt vim.option_meta
+--- @return string[]
+local function build_option_tags(opt)
+  --- @type string[]
+  local tags = { opt.full_name }
+
+  tags[#tags + 1] = opt.abbreviation
+  if opt.type == 'boolean' then
+    for i = 1, #tags do
+      tags[#tags + 1] = 'no' .. tags[i]
+    end
+  end
+
+  for i, t in ipairs(tags) do
+    tags[i] = "'" .. t .. "'"
+  end
+
+  for _, t in ipairs(opt.tags or {}) do
+    tags[#tags + 1] = t
+  end
+
+  for i, t in ipairs(tags) do
+    tags[i] = '*' .. t .. '*'
+  end
+
+  return tags
+end
+
+--- @param _f string
+--- @param opt vim.option_meta
+--- @param write fun(line: string)
+local function render_option_doc(_f, opt, write)
+  local tags = build_option_tags(opt)
+  local tag_str = table.concat(tags, ' ')
+  local conceal_offset = 2 * (#tags - 1)
+  local tag_pad = string.rep('\t', math.ceil((64 - #tag_str + conceal_offset) / 8))
+  -- local pad = string.rep(' ', 80 - #tag_str + conceal_offset)
+  write(tag_pad .. tag_str)
+
+  local name_str --- @type string
+  if opt.abbreviation then
+    name_str = fmt("'%s' '%s'", opt.full_name, opt.abbreviation)
+  else
+    name_str = fmt("'%s'", opt.full_name)
+  end
+
+  local otype = opt.type == 'boolean' and 'boolean' or opt.type
+  if opt.defaults.doc or opt.defaults.if_true ~= nil or opt.defaults.meta ~= nil then
+    local v = render_option_default(opt.defaults, true)
+    local pad = string.rep('\t', math.max(1, math.ceil((24 - #name_str) / 8)))
+    if opt.defaults.doc then
+      local deflen = #fmt('%s%s%s (', name_str, pad, otype)
+      --- @type string
+      v = v:gsub('\n', '\n' .. string.rep(' ', deflen - 2))
+    end
+    write(fmt('%s%s%s\t(default %s)', name_str, pad, otype, v))
+  else
+    write(fmt('%s\t%s', name_str, otype))
+  end
+
+  write('\t\t\t' .. scope_to_doc(opt.scope) .. scope_more_doc(opt))
+  for _, l in ipairs(split(opt.desc)) do
+    if l == '<' or l:match('^<%s') then
+      write(l)
+    else
+      write('\t' .. l:gsub('\\<', '<'))
+    end
+  end
+end
+
+--- @param _f string
+--- @param vvar vim.option_meta
+--- @param write fun(line: string)
+local function render_vvar_doc(_f, vvar, write)
+  local name = vvar.full_name
+
+  local tags = { 'v:' .. name, name .. '-variable' }
+  if vvar.tags then
+    vim.list_extend(tags, vvar.tags)
+  end
+
+  for i, t in ipairs(tags) do
+    tags[i] = '*' .. t .. '*'
+  end
+
+  local tag_str = table.concat(tags, ' ')
+  local conceal_offset = 2 * (#tags - 1)
+
+  local tag_pad = string.rep('\t', math.ceil((64 - #tag_str + conceal_offset) / 8))
+  write(tag_pad .. tag_str)
+
+  local desc = split(vvar.desc)
+
+  if (#desc == 1 or #desc == 2 and desc[2]:match('^%s*$')) and #name < 10 then
+    -- single line
+    write('v:' .. name .. '\t' .. desc[1]:gsub('^%s*', ''))
+    write('')
+  else
+    write('v:' .. name)
+    for _, l in ipairs(desc) do
+      if l == '<' or l:match('^<%s') then
+        write(l)
+      else
+        write('\t\t' .. l:gsub('\\<', '<'))
+      end
+    end
+  end
+end
+
+--- @class nvim.gen_eval_files.elem
+--- @field path string
+--- @field from? string Skip lines in path until this pattern is reached.
+--- @field funcs fun(): table<string, table>
+--- @field render fun(f:string,obj:table,write:fun(line:string))
+--- @field header? string[]
+--- @field footer? string[]
+
+--- @type nvim.gen_eval_files.elem[]
+local CONFIG = {
+  {
+    path = 'runtime/lua/vim/_meta/vimfn.lua',
+    header = LUA_META_HEADER,
+    funcs = get_eval_meta,
+    render = render_eval_meta,
+  },
+  {
+    path = 'runtime/lua/vim/_meta/api.lua',
+    header = LUA_API_META_HEADER,
+    funcs = get_api_meta,
+    render = render_api_meta,
+  },
+  {
+    path = 'runtime/lua/vim/_meta/api_keysets.lua',
+    header = LUA_META_HEADER,
+    funcs = get_api_keysets_meta,
+    render = render_api_keyset_meta,
+  },
+  {
+    path = 'runtime/doc/builtin.txt',
+    funcs = get_eval_meta,
+    render = render_eval_doc,
+    header = {
+      '*builtin.txt*	Nvim',
+      '',
+      '',
+      '\t\t  NVIM REFERENCE MANUAL',
+      '',
+      '',
+      'Builtin functions\t\t*vimscript-functions* *builtin-functions*',
+      '',
+      'For functions grouped by what they are used for see |function-list|.',
+      '',
+      '\t\t\t\t      Type |gO| to see the table of contents.',
+      '==============================================================================',
+      '1. Details					*builtin-function-details*',
+      '',
+    },
+    footer = {
+      '==============================================================================',
+      '2. Matching a pattern in a String			*string-match*',
+      '',
+      'This is common between several functions. A regexp pattern as explained at',
+      '|pattern| is normally used to find a match in the buffer lines.  When a',
+      'pattern is used to find a match in a String, almost everything works in the',
+      'same way.  The difference is that a String is handled like it is one line.',
+      'When it contains a "\\n" character, this is not seen as a line break for the',
+      'pattern.  It can be matched with a "\\n" in the pattern, or with ".".  Example:',
+      '>vim',
+      '\tlet a = "aaaa\\nxxxx"',
+      '\techo matchstr(a, "..\\n..")',
+      '\t" aa',
+      '\t" xx',
+      '\techo matchstr(a, "a.x")',
+      '\t" a',
+      '\t" x',
+      '',
+      'Don\'t forget that "^" will only match at the first character of the String and',
+      '"$" at the last character of the string.  They don\'t match after or before a',
+      '"\\n".',
+      '',
+      ' vim:tw=78:ts=8:noet:ft=help:norl:',
+    },
+  },
+  {
+    path = 'runtime/lua/vim/_meta/options.lua',
+    header = LUA_OPTION_META_HEADER,
+    funcs = get_option_meta,
+    render = render_option_meta,
+  },
+  {
+    path = 'runtime/doc/options.txt',
+    header = { '' },
+    from = 'A jump table for the options with a short description can be found at |Q_op|.',
+    footer = {
+      ' vim:tw=78:ts=8:noet:ft=help:norl:',
+    },
+    funcs = get_option_meta,
+    render = render_option_doc,
+  },
+  {
+    path = 'runtime/lua/vim/_meta/vvars.lua',
+    header = LUA_VVAR_META_HEADER,
+    funcs = get_vvar_meta,
+    render = render_vvar_meta,
+  },
+  {
+    path = 'runtime/doc/vvars.txt',
+    header = { '' },
+    from = 'Type |gO| to see the table of contents.',
+    footer = {
+      ' vim:tw=78:ts=8:noet:ft=help:norl:',
+    },
+    funcs = get_vvar_meta,
+    render = render_vvar_doc,
+  },
+}
+
+--- @param elem nvim.gen_eval_files.elem
+local function render(elem)
+  print('Rendering ' .. elem.path)
+  local from_lines = {} --- @type string[]
+  local from = elem.from
+  if from then
+    for line in io.lines(elem.path) do
+      from_lines[#from_lines + 1] = line
+      if line:match(from) then
+        break
+      end
+    end
+  end
+
+  local o = assert(io.open(elem.path, 'w'))
+
+  --- @param l string
+  local function write(l)
+    local l1 = l:gsub('%s+$', '')
+    o:write(l1)
+    o:write('\n')
+  end
+
+  for _, l in ipairs(from_lines) do
+    write(l)
+  end
+
+  for _, l in ipairs(elem.header or {}) do
+    write(l)
+  end
+
+  local funcs = elem.funcs()
+
+  --- @type string[]
+  local fnames = vim.tbl_keys(funcs)
+  table.sort(fnames)
+
+  for _, f in ipairs(fnames) do
+    elem.render(f, funcs[f], write)
+  end
+
+  for _, l in ipairs(elem.footer or {}) do
+    write(l)
+  end
+
+  o:close()
+end
+
+local function main()
+  for _, c in ipairs(CONFIG) do
+    render(c)
+  end
+end
+
+main()
diff --git a/src/gen/gen_events.lua b/src/gen/gen_events.lua
new file mode 100644
index 0000000000..77f766bb28
--- /dev/null
+++ b/src/gen/gen_events.lua
@@ -0,0 +1,42 @@
+local fileio_enum_file = arg[1]
+local names_file = arg[2]
+
+local auevents = require('nvim.auevents')
+local events = auevents.events
+
+local enum_tgt = io.open(fileio_enum_file, 'w')
+local names_tgt = io.open(names_file, 'w')
+
+enum_tgt:write([[
+// IWYU pragma: private, include "nvim/autocmd_defs.h"
+
+typedef enum auto_event {]])
+names_tgt:write([[
+static const struct event_name {
+  size_t len;
+  char *name;
+  int event;
+} event_names[] = {]])
+
+local aliases = 0
+for i, event in ipairs(events) do
+  enum_tgt:write(('\n  EVENT_%s = %u,'):format(event[1]:upper(), i + aliases - 1))
+  -- Events with positive keys aren't allowed in 'eventignorewin'.
+  local event_int = ('%sEVENT_%s'):format(event[3] and '-' or '', event[1]:upper())
+  names_tgt:write(('\n  {%u, "%s", %s},'):format(#event[1], event[1], event_int))
+  for _, alias in ipairs(event[2]) do
+    aliases = aliases + 1
+    names_tgt:write(('\n  {%u, "%s", %s},'):format(#alias, alias, event_int))
+    enum_tgt:write(('\n  EVENT_%s = %u,'):format(alias:upper(), i + aliases - 1))
+  end
+  if i == #events then -- Last item.
+    enum_tgt:write(('\n  NUM_EVENTS = %u,'):format(i + aliases))
+  end
+end
+
+names_tgt:write('\n  {0, NULL, (event_T)0},\n};\n')
+names_tgt:write('\nstatic AutoCmdVec autocmds[NUM_EVENTS] = { 0 };\n')
+names_tgt:close()
+
+enum_tgt:write('\n} event_T;\n')
+enum_tgt:close()
diff --git a/src/gen/gen_ex_cmds.lua b/src/gen/gen_ex_cmds.lua
new file mode 100644
index 0000000000..6c03e8fc4d
--- /dev/null
+++ b/src/gen/gen_ex_cmds.lua
@@ -0,0 +1,194 @@
+local includedir = arg[1]
+local autodir = arg[2]
+
+-- Will generate files ex_cmds_enum.generated.h with cmdidx_T enum
+-- and ex_cmds_defs.generated.h with main Ex commands definitions.
+
+local enumfname = includedir .. '/ex_cmds_enum.generated.h'
+local defsfname = autodir .. '/ex_cmds_defs.generated.h'
+
+local enumfile = io.open(enumfname, 'w')
+local defsfile = io.open(defsfname, 'w')
+
+local bit = require 'bit'
+local ex_cmds = require('nvim.ex_cmds')
+local defs = ex_cmds.cmds
+local flags = ex_cmds.flags
+
+local byte_a = string.byte('a')
+local byte_z = string.byte('z')
+local a_to_z = byte_z - byte_a + 1
+
+-- Table giving the index of the first command in cmdnames[] to lookup
+-- based on the first letter of a command.
+local cmdidxs1_out = string.format(
+  [[
+static const uint16_t cmdidxs1[%u] = {
+]],
+  a_to_z
+)
+-- Table giving the index of the first command in cmdnames[] to lookup
+-- based on the first 2 letters of a command.
+-- Values in cmdidxs2[c1][c2] are relative to cmdidxs1[c1] so that they
+-- fit in a byte.
+local cmdidxs2_out = string.format(
+  [[
+static const uint8_t cmdidxs2[%u][%u] = {
+  /*           a   b   c   d   e   f   g   h   i   j   k   l   m   n   o   p   q   r   s   t   u   v   w   x   y   z */
+]],
+  a_to_z,
+  a_to_z
+)
+
+enumfile:write([[
+// IWYU pragma: private, include "nvim/ex_cmds_defs.h"
+
+typedef enum CMD_index {
+]])
+defsfile:write(string.format(
+  [[
+#include "nvim/arglist.h"
+#include "nvim/autocmd.h"
+#include "nvim/buffer.h"
+#include "nvim/cmdhist.h"
+#include "nvim/debugger.h"
+#include "nvim/diff.h"
+#include "nvim/digraph.h"
+#include "nvim/eval.h"
+#include "nvim/eval/userfunc.h"
+#include "nvim/eval/vars.h"
+#include "nvim/ex_cmds.h"
+#include "nvim/ex_cmds2.h"
+#include "nvim/ex_docmd.h"
+#include "nvim/ex_eval.h"
+#include "nvim/ex_session.h"
+#include "nvim/help.h"
+#include "nvim/indent.h"
+#include "nvim/lua/executor.h"
+#include "nvim/lua/secure.h"
+#include "nvim/mapping.h"
+#include "nvim/mark.h"
+#include "nvim/match.h"
+#include "nvim/menu.h"
+#include "nvim/message.h"
+#include "nvim/ops.h"
+#include "nvim/option.h"
+#include "nvim/os/lang.h"
+#include "nvim/profile.h"
+#include "nvim/quickfix.h"
+#include "nvim/runtime.h"
+#include "nvim/sign.h"
+#include "nvim/spell.h"
+#include "nvim/spellfile.h"
+#include "nvim/syntax.h"
+#include "nvim/undo.h"
+#include "nvim/usercmd.h"
+#include "nvim/version.h"
+
+static const int command_count = %u;
+static CommandDefinition cmdnames[%u] = {
+]],
+  #defs,
+  #defs
+))
+local cmds, cmdidxs1, cmdidxs2 = {}, {}, {}
+for _, cmd in ipairs(defs) do
+  if bit.band(cmd.flags, flags.RANGE) == flags.RANGE then
+    assert(
+      cmd.addr_type ~= 'ADDR_NONE',
+      string.format('ex_cmds.lua:%s: Using RANGE with ADDR_NONE\n', cmd.command)
+    )
+  else
+    assert(
+      cmd.addr_type == 'ADDR_NONE',
+      string.format('ex_cmds.lua:%s: Missing ADDR_NONE\n', cmd.command)
+    )
+  end
+  if bit.band(cmd.flags, flags.DFLALL) == flags.DFLALL then
+    assert(
+      cmd.addr_type ~= 'ADDR_OTHER' and cmd.addr_type ~= 'ADDR_NONE',
+      string.format('ex_cmds.lua:%s: Missing misplaced DFLALL\n', cmd.command)
+    )
+  end
+  if bit.band(cmd.flags, flags.PREVIEW) == flags.PREVIEW then
+    assert(
+      cmd.preview_func ~= nil,
+      string.format('ex_cmds.lua:%s: Missing preview_func\n', cmd.command)
+    )
+  end
+  local enumname = cmd.enum or ('CMD_' .. cmd.command)
+  local byte_cmd = cmd.command:sub(1, 1):byte()
+  if byte_a <= byte_cmd and byte_cmd <= byte_z then
+    table.insert(cmds, cmd.command)
+  end
+  local preview_func
+  if cmd.preview_func then
+    preview_func = string.format('&%s', cmd.preview_func)
+  else
+    preview_func = 'NULL'
+  end
+  enumfile:write('  ' .. enumname .. ',\n')
+  defsfile:write(string.format(
+    [[
+  [%s] = {
+    .cmd_name = "%s",
+    .cmd_func = (ex_func_T)&%s,
+    .cmd_preview_func = %s,
+    .cmd_argt = %uL,
+    .cmd_addr_type = %s
+  },
+]],
+    enumname,
+    cmd.command,
+    cmd.func,
+    preview_func,
+    cmd.flags,
+    cmd.addr_type
+  ))
+end
+for i = #cmds, 1, -1 do
+  local cmd = cmds[i]
+  -- First and second characters of the command
+  local c1 = cmd:sub(1, 1)
+  cmdidxs1[c1] = i - 1
+  if cmd:len() >= 2 then
+    local c2 = cmd:sub(2, 2)
+    local byte_c2 = string.byte(c2)
+    if byte_a <= byte_c2 and byte_c2 <= byte_z then
+      if not cmdidxs2[c1] then
+        cmdidxs2[c1] = {}
+      end
+      cmdidxs2[c1][c2] = i - 1
+    end
+  end
+end
+for i = byte_a, byte_z do
+  local c1 = string.char(i)
+  cmdidxs1_out = cmdidxs1_out .. '  /*  ' .. c1 .. '  */ ' .. cmdidxs1[c1] .. ',\n'
+  cmdidxs2_out = cmdidxs2_out .. '  /*  ' .. c1 .. '  */ {'
+  for j = byte_a, byte_z do
+    local c2 = string.char(j)
+    cmdidxs2_out = cmdidxs2_out
+      .. ((cmdidxs2[c1] and cmdidxs2[c1][c2]) and string.format(
+        '%3d',
+        cmdidxs2[c1][c2] - cmdidxs1[c1]
+      ) or '  0')
+      .. ','
+  end
+  cmdidxs2_out = cmdidxs2_out .. ' },\n'
+end
+enumfile:write([[
+  CMD_SIZE,
+  CMD_USER = -1,
+  CMD_USER_BUF = -2
+} cmdidx_T;
+]])
+defsfile:write(string.format(
+  [[
+};
+%s};
+%s};
+]],
+  cmdidxs1_out,
+  cmdidxs2_out
+))
diff --git a/src/gen/gen_filetype.lua b/src/gen/gen_filetype.lua
new file mode 100644
index 0000000000..18b53f1ea4
--- /dev/null
+++ b/src/gen/gen_filetype.lua
@@ -0,0 +1,209 @@
+local do_not_run = true
+if do_not_run then
+  print([[
+    This script was used to bootstrap the filetype patterns in runtime/lua/vim/filetype.lua. It
+    should no longer be used except for testing purposes. New filetypes, or changes to existing
+    filetypes, should be ported manually as part of the vim-patch process.
+  ]])
+  return
+end
+
+local filetype_vim = 'runtime/filetype.vim'
+local filetype_lua = 'runtime/lua/vim/filetype.lua'
+
+local keywords = {
+  ['for'] = true,
+  ['or'] = true,
+  ['and'] = true,
+  ['end'] = true,
+  ['do'] = true,
+  ['if'] = true,
+  ['while'] = true,
+  ['repeat'] = true,
+}
+
+local sections = {
+  extension = { str = {}, func = {} },
+  filename = { str = {}, func = {} },
+  pattern = { str = {}, func = {} },
+}
+
+local specialchars = '%*%?\\%$%[%]%{%}'
+
+local function add_pattern(pat, ft)
+  local ok = true
+
+  -- Patterns that start or end with { or } confuse splitting on commas and make parsing harder, so just skip those
+  if not string.find(pat, '^%{') and not string.find(pat, '%}$') then
+    for part in string.gmatch(pat, '[^,]+') do
+      if not string.find(part, '[' .. specialchars .. ']') then
+        if type(ft) == 'string' then
+          sections.filename.str[part] = ft
+        else
+          sections.filename.func[part] = ft
+        end
+      elseif string.match(part, '^%*%.[^%./' .. specialchars .. ']+$') then
+        if type(ft) == 'string' then
+          sections.extension.str[part:sub(3)] = ft
+        else
+          sections.extension.func[part:sub(3)] = ft
+        end
+      else
+        if string.match(part, '^%*/[^' .. specialchars .. ']+$') then
+          -- For patterns matching */some/pattern we want to easily match files
+          -- with path /some/pattern, so include those in filename detection
+          if type(ft) == 'string' then
+            sections.filename.str[part:sub(2)] = ft
+          else
+            sections.filename.func[part:sub(2)] = ft
+          end
+        end
+
+        if string.find(part, '^[%w-_.*?%[%]/]+$') then
+          local p = part:gsub('%.', '%%.'):gsub('%*', '.*'):gsub('%?', '.')
+          -- Insert into array to maintain order rather than setting
+          -- key-value directly
+          if type(ft) == 'string' then
+            sections.pattern.str[p] = ft
+          else
+            sections.pattern.func[p] = ft
+          end
+        else
+          ok = false
+        end
+      end
+    end
+  end
+
+  return ok
+end
+
+local function parse_line(line)
+  local pat, ft
+  pat, ft = line:match('^%s*au%a* Buf[%a,]+%s+(%S+)%s+setf%s+(%S+)')
+  if pat then
+    return add_pattern(pat, ft)
+  else
+    local func
+    pat, func = line:match('^%s*au%a* Buf[%a,]+%s+(%S+)%s+call%s+(%S+)')
+    if pat then
+      return add_pattern(pat, function()
+        return func
+      end)
+    end
+  end
+end
+
+local unparsed = {}
+local full_line
+for line in io.lines(filetype_vim) do
+  local cont = string.match(line, '^%s*\\%s*(.*)$')
+  if cont then
+    full_line = full_line .. ' ' .. cont
+  else
+    if full_line then
+      if not parse_line(full_line) and string.find(full_line, '^%s*au%a* Buf') then
+        table.insert(unparsed, full_line)
+      end
+    end
+    full_line = line
+  end
+end
+
+if #unparsed > 0 then
+  print('Failed to parse the following patterns:')
+  for _, v in ipairs(unparsed) do
+    print(v)
+  end
+end
+
+local function add_item(indent, key, ft)
+  if type(ft) == 'string' then
+    if string.find(key, '%A') or keywords[key] then
+      key = string.format('["%s"]', key)
+    end
+    return string.format([[%s%s = "%s",]], indent, key, ft)
+  elseif type(ft) == 'function' then
+    local func = ft()
+    if string.find(key, '%A') or keywords[key] then
+      key = string.format('["%s"]', key)
+    end
+    -- Right now only a single argument is supported, which covers
+    -- everything in filetype.vim as of this writing
+    local arg = string.match(func, '%((.*)%)$')
+    func = string.gsub(func, '%(.*$', '')
+    if arg == '' then
+      -- Function with no arguments, call the function directly
+      return string.format([[%s%s = function() vim.fn["%s"]() end,]], indent, key, func)
+    elseif string.match(arg, [[^(["']).*%1$]]) then
+      -- String argument
+      if func == 's:StarSetf' then
+        return string.format([[%s%s = starsetf(%s),]], indent, key, arg)
+      else
+        return string.format([[%s%s = function() vim.fn["%s"](%s) end,]], indent, key, func, arg)
+      end
+    elseif string.find(arg, '%(') then
+      -- Function argument
+      return string.format(
+        [[%s%s = function() vim.fn["%s"](vim.fn.%s) end,]],
+        indent,
+        key,
+        func,
+        arg
+      )
+    else
+      assert(false, arg)
+    end
+  end
+end
+
+do
+  local lines = {}
+  local start = false
+  for line in io.lines(filetype_lua) do
+    if line:match('^%s+-- END [A-Z]+$') then
+      start = false
+    end
+
+    if not start then
+      table.insert(lines, line)
+    end
+
+    local indent, section = line:match('^(%s+)-- BEGIN ([A-Z]+)$')
+    if section then
+      start = true
+      local t = sections[string.lower(section)]
+
+      local sorted = {}
+      for k, v in pairs(t.str) do
+        table.insert(sorted, { [k] = v })
+      end
+
+      table.sort(sorted, function(a, b)
+        return a[next(a)] < b[next(b)]
+      end)
+
+      for _, v in ipairs(sorted) do
+        local k = next(v)
+        table.insert(lines, add_item(indent, k, v[k]))
+      end
+
+      sorted = {}
+      for k, v in pairs(t.func) do
+        table.insert(sorted, { [k] = v })
+      end
+
+      table.sort(sorted, function(a, b)
+        return next(a) < next(b)
+      end)
+
+      for _, v in ipairs(sorted) do
+        local k = next(v)
+        table.insert(lines, add_item(indent, k, v[k]))
+      end
+    end
+  end
+  local f = io.open(filetype_lua, 'w')
+  f:write(table.concat(lines, '\n') .. '\n')
+  f:close()
+end
diff --git a/src/gen/gen_help_html.lua b/src/gen/gen_help_html.lua
new file mode 100644
index 0000000000..53a65fd65f
--- /dev/null
+++ b/src/gen/gen_help_html.lua
@@ -0,0 +1,1491 @@
+--- Converts Nvim :help files to HTML.  Validates |tag| links and document syntax (parser errors).
+--
+-- USAGE (For CI/local testing purposes): Simply `make lintdoc` or `scripts/lintdoc.lua`, which
+-- basically does the following:
+--   1. :helptags ALL
+--   2. nvim -V1 -es +"lua require('scripts.gen_help_html').run_validate()" +q
+--   3. nvim -V1 -es +"lua require('scripts.gen_help_html').test_gen()" +q
+--
+-- USAGE (GENERATE HTML):
+--   1. `:helptags ALL` first; this script depends on vim.fn.taglist().
+--   2. nvim -V1 -es --clean +"lua require('scripts.gen_help_html').gen('./runtime/doc', 'target/dir/')" +q
+--      - Read the docstring at gen().
+--   3. cd target/dir/ && jekyll serve --host 0.0.0.0
+--   4. Visit http://localhost:4000/…/help.txt.html
+--
+-- USAGE (VALIDATE):
+--   1. nvim -V1 -es +"lua require('scripts.gen_help_html').validate('./runtime/doc')" +q
+--      - validate() is 10x faster than gen(), so it is used in CI.
+--
+-- SELF-TEST MODE:
+--   1. nvim -V1 -es +"lua require('scripts.gen_help_html')._test()" +q
+--
+-- NOTES:
+--   * This script is used by the automation repo: https://github.com/neovim/doc
+--   * :helptags checks for duplicate tags, whereas this script checks _links_ (to tags).
+--   * gen() and validate() are the primary (programmatic) entrypoints. validate() only exists
+--     because gen() is too slow (~1 min) to run in per-commit CI.
+--   * visit_node() is the core function used by gen() to traverse the document tree and produce HTML.
+--   * visit_validate() is the core function used by validate().
+--   * Files in `new_layout` will be generated with a "flow" layout instead of preformatted/fixed-width layout.
+
+local tagmap = nil ---@type table<string, string>
+local helpfiles = nil ---@type string[]
+local invalid_links = {} ---@type table<string, any>
+local invalid_urls = {} ---@type table<string, any>
+local invalid_spelling = {} ---@type table<string, table<string, string>>
+local spell_dict = {
+  Neovim = 'Nvim',
+  NeoVim = 'Nvim',
+  neovim = 'Nvim',
+  lua = 'Lua',
+  VimL = 'Vimscript',
+  vimL = 'Vimscript',
+  viml = 'Vimscript',
+  ['tree-sitter'] = 'treesitter',
+  ['Tree-sitter'] = 'Treesitter',
+}
+--- specify the list of keywords to ignore (i.e. allow), or true to disable spell check completely.
+--- @type table<string, true|string[]>
+local spell_ignore_files = {
+  ['credits.txt'] = { 'Neovim' },
+  ['news.txt'] = { 'tree-sitter' }, -- in news, may refer to the upstream "tree-sitter" library
+  ['news-0.10.txt'] = { 'tree-sitter' },
+}
+local language = nil
+
+local M = {}
+
+-- These files are generated with "flow" layout (non fixed-width, wrapped text paragraphs).
+-- All other files are "legacy" files which require fixed-width layout.
+local new_layout = {
+  ['api.txt'] = true,
+  ['lsp.txt'] = true,
+  ['channel.txt'] = true,
+  ['deprecated.txt'] = true,
+  ['develop.txt'] = true,
+  ['dev_style.txt'] = true,
+  ['dev_theme.txt'] = true,
+  ['dev_tools.txt'] = true,
+  ['dev_vimpatch.txt'] = true,
+  ['editorconfig.txt'] = true,
+  ['faq.txt'] = true,
+  ['gui.txt'] = true,
+  ['intro.txt'] = true,
+  ['lua.txt'] = true,
+  ['luaref.txt'] = true,
+  ['news.txt'] = true,
+  ['news-0.9.txt'] = true,
+  ['news-0.10.txt'] = true,
+  ['nvim.txt'] = true,
+  ['provider.txt'] = true,
+  ['tui.txt'] = true,
+  ['ui.txt'] = true,
+  ['vim_diff.txt'] = true,
+}
+
+-- Map of new:old pages, to redirect renamed pages.
+local redirects = {
+  ['credits'] = 'backers',
+  ['tui'] = 'term',
+  ['terminal'] = 'nvim_terminal_emulator',
+}
+
+-- TODO: These known invalid |links| require an update to the relevant docs.
+local exclude_invalid = {
+  ["'string'"] = 'eval.txt',
+  Query = 'treesitter.txt',
+  matchit = 'vim_diff.txt',
+  ['set!'] = 'treesitter.txt',
+}
+
+-- False-positive "invalid URLs".
+local exclude_invalid_urls = {
+  ['http://'] = 'usr_23.txt',
+  ['http://.'] = 'usr_23.txt',
+  ['http://aspell.net/man-html/Affix-Compression.html'] = 'spell.txt',
+  ['http://aspell.net/man-html/Phonetic-Code.html'] = 'spell.txt',
+  ['http://canna.sourceforge.jp/'] = 'mbyte.txt',
+  ['http://gnuada.sourceforge.net'] = 'ft_ada.txt',
+  ['http://lua-users.org/wiki/StringLibraryTutorial'] = 'lua.txt',
+  ['http://michael.toren.net/code/'] = 'pi_tar.txt',
+  ['http://papp.plan9.de'] = 'syntax.txt',
+  ['http://wiki.services.openoffice.org/wiki/Dictionaries'] = 'spell.txt',
+  ['http://www.adapower.com'] = 'ft_ada.txt',
+  ['http://www.jclark.com/'] = 'quickfix.txt',
+  ['http://oldblog.antirez.com/post/redis-and-scripting.html'] = 'faq.txt',
+}
+
+-- Deprecated, brain-damaged files that I don't care about.
+local ignore_errors = {
+  ['pi_netrw.txt'] = true,
+  ['credits.txt'] = true,
+}
+
+local function tofile(fname, text)
+  local f = io.open(fname, 'w')
+  if not f then
+    error(('failed to write: %s'):format(f))
+  else
+    f:write(text)
+    f:close()
+  end
+end
+
+---@type fun(s: string): string
+local function html_esc(s)
+  return (s:gsub('&', '&amp;'):gsub('<', '&lt;'):gsub('>', '&gt;'))
+end
+
+local function url_encode(s)
+  -- Credit: tpope / vim-unimpaired
+  -- NOTE: these chars intentionally *not* escaped: ' ( )
+  return vim.fn.substitute(
+    vim.fn.iconv(s, 'latin1', 'utf-8'),
+    [=[[^A-Za-z0-9()'_.~-]]=],
+    [=[\="%".printf("%02X",char2nr(submatch(0)))]=],
+    'g'
+  )
+end
+
+local function expandtabs(s)
+  return s:gsub('\t', (' '):rep(8)) --[[ @as string ]]
+end
+
+local function to_titlecase(s)
+  local text = ''
+  for w in vim.gsplit(s, '[ \t]+') do
+    text = ('%s %s%s'):format(text, vim.fn.toupper(w:sub(1, 1)), w:sub(2))
+  end
+  return text
+end
+
+local function to_heading_tag(text)
+  -- Prepend "_" to avoid conflicts with actual :help tags.
+  return text and string.format('_%s', vim.fn.tolower((text:gsub('%s+', '-')))) or 'unknown'
+end
+
+local function basename_noext(f)
+  return vim.fs.basename(f:gsub('%.txt', ''))
+end
+
+local function is_blank(s)
+  return not not s:find([[^[\t ]*$]])
+end
+
+---@type fun(s: string, dir?:0|1|2): string
+local function trim(s, dir)
+  return vim.fn.trim(s, '\r\t\n ', dir or 0)
+end
+
+--- Removes common punctuation from URLs.
+---
+--- TODO: fix this in the parser instead... https://github.com/neovim/tree-sitter-vimdoc
+---
+--- @param url string
+--- @return string, string (fixed_url, removed_chars) where `removed_chars` is in the order found in the input.
+local function fix_url(url)
+  local removed_chars = ''
+  local fixed_url = url
+  -- Remove up to one of each char from end of the URL, in this order.
+  for _, c in ipairs({ '.', ')' }) do
+    if fixed_url:sub(-1) == c then
+      removed_chars = c .. removed_chars
+      fixed_url = fixed_url:sub(1, -2)
+    end
+  end
+  return fixed_url, removed_chars
+end
+
+--- Checks if a given line is a "noise" line that doesn't look good in HTML form.
+local function is_noise(line, noise_lines)
+  if
+    -- First line is always noise.
+    (noise_lines ~= nil and vim.tbl_count(noise_lines) == 0)
+    or line:find('Type .*gO.* to see the table of contents')
+    -- Title line of traditional :help pages.
+    -- Example: "NVIM REFERENCE MANUAL    by ..."
+    or line:find([[^%s*N?VIM[ \t]*REFERENCE[ \t]*MANUAL]])
+    -- First line of traditional :help pages.
+    -- Example: "*api.txt*    Nvim"
+    or line:find('%s*%*?[a-zA-Z]+%.txt%*?%s+N?[vV]im%s*$')
+    -- modeline
+    -- Example: "vim:tw=78:ts=8:sw=4:sts=4:et:ft=help:norl:"
+    or line:find('^%s*vim?%:.*ft=help')
+    or line:find('^%s*vim?%:.*filetype=help')
+    or line:find('[*>]local%-additions[*<]')
+  then
+    -- table.insert(stats.noise_lines, getbuflinestr(root, opt.buf, 0))
+    table.insert(noise_lines or {}, line)
+    return true
+  end
+  return false
+end
+
+--- Creates a github issue URL at neovim/tree-sitter-vimdoc with prefilled content.
+--- @return string
+local function get_bug_url_vimdoc(fname, to_fname, sample_text)
+  local this_url = string.format('https://neovim.io/doc/user/%s', vim.fs.basename(to_fname))
+  local bug_url = (
+    'https://github.com/neovim/tree-sitter-vimdoc/issues/new?labels=bug&title=parse+error%3A+'
+    .. vim.fs.basename(fname)
+    .. '+&body=Found+%60tree-sitter-vimdoc%60+parse+error+at%3A+'
+    .. this_url
+    .. '%0D%0DContext%3A%0D%0D%60%60%60%0D'
+    .. url_encode(sample_text)
+    .. '%0D%60%60%60'
+  )
+  return bug_url
+end
+
+--- Creates a github issue URL at neovim/neovim with prefilled content.
+--- @return string
+local function get_bug_url_nvim(fname, to_fname, sample_text, token_name)
+  local this_url = string.format('https://neovim.io/doc/user/%s', vim.fs.basename(to_fname))
+  local bug_url = (
+    'https://github.com/neovim/neovim/issues/new?labels=bug&title=user+docs+HTML%3A+'
+    .. vim.fs.basename(fname)
+    .. '+&body=%60gen_help_html.lua%60+problem+at%3A+'
+    .. this_url
+    .. '%0D'
+    .. (token_name and '+unhandled+token%3A+%60' .. token_name .. '%60' or '')
+    .. '%0DContext%3A%0D%0D%60%60%60%0D'
+    .. url_encode(sample_text)
+    .. '%0D%60%60%60'
+  )
+  return bug_url
+end
+
+--- Gets a "foo.html" name from a "foo.txt" helpfile name.
+local function get_helppage(f)
+  if not f then
+    return nil
+  end
+  -- Special case: help.txt is the "main landing page" of :help files, not index.txt.
+  if f == 'index.txt' then
+    return 'vimindex.html'
+  elseif f == 'help.txt' then
+    return 'index.html'
+  end
+
+  return (f:gsub('%.txt$', '')) .. '.html'
+end
+
+--- Counts leading spaces (tab=8) to decide the indent size of multiline text.
+---
+--- Blank lines (empty or whitespace-only) are ignored.
+local function get_indent(s)
+  local min_indent = nil
+  for line in vim.gsplit(s, '\n') do
+    if line and not is_blank(line) then
+      local ws = expandtabs(line:match('^%s+') or '')
+      min_indent = (not min_indent or ws:len() < min_indent) and ws:len() or min_indent
+    end
+  end
+  return min_indent or 0
+end
+
+--- Removes the common indent level, after expanding tabs to 8 spaces.
+local function trim_indent(s)
+  local indent_size = get_indent(s)
+  local trimmed = ''
+  for line in vim.gsplit(s, '\n') do
+    line = expandtabs(line)
+    trimmed = ('%s%s\n'):format(trimmed, line:sub(indent_size + 1))
+  end
+  return trimmed:sub(1, -2)
+end
+
+--- Gets raw buffer text in the node's range (+/- an offset), as a newline-delimited string.
+---@param node TSNode
+---@param bufnr integer
+---@param offset integer
+local function getbuflinestr(node, bufnr, offset)
+  local line1, _, line2, _ = node:range()
+  line1 = line1 - offset
+  line2 = line2 + offset
+  local lines = vim.fn.getbufline(bufnr, line1 + 1, line2 + 1)
+  return table.concat(lines, '\n')
+end
+
+--- Gets the whitespace just before `node` from the raw buffer text.
+--- Needed for preformatted `old` lines.
+---@param node TSNode
+---@param bufnr integer
+---@return string
+local function getws(node, bufnr)
+  local line1, c1, line2, _ = node:range()
+  ---@type string
+  local raw = vim.fn.getbufline(bufnr, line1 + 1, line2 + 1)[1]
+  local text_before = raw:sub(1, c1)
+  local leading_ws = text_before:match('%s+$') or ''
+  return leading_ws
+end
+
+local function get_tagname(node, bufnr)
+  local text = vim.treesitter.get_node_text(node, bufnr)
+  local tag = (node:type() == 'optionlink' or node:parent():type() == 'optionlink')
+      and ("'%s'"):format(text)
+    or text
+  local helpfile = vim.fs.basename(tagmap[tag]) or nil -- "api.txt"
+  local helppage = get_helppage(helpfile) -- "api.html"
+  return helppage, tag
+end
+
+--- Returns true if the given invalid tagname is a false positive.
+local function ignore_invalid(s)
+  return not not (
+    exclude_invalid[s]
+    -- Strings like |~/====| appear in various places and the parser thinks they are links, but they
+    -- are just table borders.
+    or s:find('===')
+    or s:find('%-%-%-')
+  )
+end
+
+local function ignore_parse_error(fname, s)
+  if ignore_errors[vim.fs.basename(fname)] then
+    return true
+  end
+  -- Ignore parse errors for unclosed tag.
+  -- This is common in vimdocs and is treated as plaintext by :help.
+  return s:find("^[`'|*]")
+end
+
+---@param node TSNode
+local function has_ancestor(node, ancestor_name)
+  local p = node ---@type TSNode?
+  while p do
+    p = p:parent()
+    if not p or p:type() == 'help_file' then
+      break
+    elseif p:type() == ancestor_name then
+      return true
+    end
+  end
+  return false
+end
+
+--- Gets the first matching child node matching `name`.
+---@param node TSNode
+local function first(node, name)
+  for c, _ in node:iter_children() do
+    if c:named() and c:type() == name then
+      return c
+    end
+  end
+  return nil
+end
+
+local function validate_link(node, bufnr, fname)
+  local helppage, tagname = get_tagname(node:child(1), bufnr)
+  local ignored = false
+  if not tagmap[tagname] then
+    ignored = has_ancestor(node, 'column_heading') or node:has_error() or ignore_invalid(tagname)
+    if not ignored then
+      invalid_links[tagname] = vim.fs.basename(fname)
+    end
+  end
+  return helppage, tagname, ignored
+end
+
+--- TODO: port the logic from scripts/check_urls.vim
+local function validate_url(text, fname)
+  local ignored = false
+  if ignore_errors[vim.fs.basename(fname)] then
+    ignored = true
+  elseif text:find('http%:') and not exclude_invalid_urls[text] then
+    invalid_urls[text] = vim.fs.basename(fname)
+  end
+  return ignored
+end
+
+--- Traverses the tree at `root` and checks that |tag| links point to valid helptags.
+---@param root TSNode
+---@param level integer
+---@param lang_tree TSTree
+---@param opt table
+---@param stats table
+local function visit_validate(root, level, lang_tree, opt, stats)
+  level = level or 0
+  local node_name = (root.named and root:named()) and root:type() or nil
+  -- Parent kind (string).
+  local parent = root:parent() and root:parent():type() or nil
+  local toplevel = level < 1
+  local function node_text(node)
+    return vim.treesitter.get_node_text(node or root, opt.buf)
+  end
+  local text = trim(node_text())
+
+  if root:child_count() > 0 then
+    for node, _ in root:iter_children() do
+      if node:named() then
+        visit_validate(node, level + 1, lang_tree, opt, stats)
+      end
+    end
+  end
+
+  if node_name == 'ERROR' then
+    if ignore_parse_error(opt.fname, text) then
+      return
+    end
+    -- Store the raw text to give context to the error report.
+    local sample_text = not toplevel and getbuflinestr(root, opt.buf, 0) or '[top level!]'
+    -- Flatten the sample text to a single, truncated line.
+    sample_text = vim.trim(sample_text):gsub('[\t\n]', ' '):sub(1, 80)
+    table.insert(stats.parse_errors, sample_text)
+  elseif
+    (node_name == 'word' or node_name == 'uppercase_name')
+    and (not vim.tbl_contains({ 'codespan', 'taglink', 'tag' }, parent))
+  then
+    local text_nopunct = vim.fn.trim(text, '.,', 0) -- Ignore some punctuation.
+    local fname_basename = assert(vim.fs.basename(opt.fname))
+    if spell_dict[text_nopunct] then
+      local should_ignore = (
+        spell_ignore_files[fname_basename] == true
+        or vim.tbl_contains(
+          (spell_ignore_files[fname_basename] or {}) --[[ @as string[] ]],
+          text_nopunct
+        )
+      )
+      if not should_ignore then
+        invalid_spelling[text_nopunct] = invalid_spelling[text_nopunct] or {}
+        invalid_spelling[text_nopunct][fname_basename] = node_text(root:parent())
+      end
+    end
+  elseif node_name == 'url' then
+    local fixed_url, _ = fix_url(trim(text))
+    validate_url(fixed_url, opt.fname)
+  elseif node_name == 'taglink' or node_name == 'optionlink' then
+    local _, _, _ = validate_link(root, opt.buf, opt.fname)
+  end
+end
+
+-- Fix tab alignment issues caused by concealed characters like |, `, * in tags
+-- and code blocks.
+---@param text string
+---@param next_node_text string
+local function fix_tab_after_conceal(text, next_node_text)
+  -- Vim tabs take into account the two concealed characters even though they
+  -- are invisible, so we need to add back in the two spaces if this is
+  -- followed by a tab to make the tab alignment to match Vim's behavior.
+  if string.sub(next_node_text, 1, 1) == '\t' then
+    text = text .. '  '
+  end
+  return text
+end
+
+---@class (exact) nvim.gen_help_html.heading
+---@field name string
+---@field subheadings nvim.gen_help_html.heading[]
+---@field tag string
+
+-- Generates HTML from node `root` recursively.
+---@param root TSNode
+---@param level integer
+---@param lang_tree TSTree
+---@param headings nvim.gen_help_html.heading[]
+---@param opt table
+---@param stats table
+local function visit_node(root, level, lang_tree, headings, opt, stats)
+  level = level or 0
+
+  local node_name = (root.named and root:named()) and root:type() or nil
+  -- Previous sibling kind (string).
+  local prev = root:prev_sibling()
+      and (root:prev_sibling().named and root:prev_sibling():named())
+      and root:prev_sibling():type()
+    or nil
+  -- Next sibling kind (string).
+  local next_ = root:next_sibling()
+      and (root:next_sibling().named and root:next_sibling():named())
+      and root:next_sibling():type()
+    or nil
+  -- Parent kind (string).
+  local parent = root:parent() and root:parent():type() or nil
+  -- Gets leading whitespace of `node`.
+  local function ws(node)
+    node = node or root
+    local ws_ = getws(node, opt.buf)
+    -- XXX: first node of a (line) includes whitespace, even after
+    -- https://github.com/neovim/tree-sitter-vimdoc/pull/31 ?
+    if ws_ == '' then
+      ws_ = vim.treesitter.get_node_text(node, opt.buf):match('^%s+') or ''
+    end
+    return ws_
+  end
+  local function node_text(node, ws_)
+    node = node or root
+    ws_ = (ws_ == nil or ws_ == true) and getws(node, opt.buf) or ''
+    return string.format('%s%s', ws_, vim.treesitter.get_node_text(node, opt.buf))
+  end
+
+  local text = ''
+  local trimmed ---@type string
+  if root:named_child_count() == 0 or node_name == 'ERROR' then
+    text = node_text()
+    trimmed = html_esc(trim(text))
+    text = html_esc(text)
+  else
+    -- Process children and join them with whitespace.
+    for node, _ in root:iter_children() do
+      if node:named() then
+        local r = visit_node(node, level + 1, lang_tree, headings, opt, stats)
+        text = string.format('%s%s', text, r)
+      end
+    end
+    trimmed = trim(text)
+  end
+
+  if node_name == 'help_file' then -- root node
+    return text
+  elseif node_name == 'url' then
+    local fixed_url, removed_chars = fix_url(trimmed)
+    return ('%s<a href="%s">%s</a>%s'):format(ws(), fixed_url, fixed_url, removed_chars)
+  elseif node_name == 'word' or node_name == 'uppercase_name' then
+    return text
+  elseif node_name == 'note' then
+    return ('<b>%s</b>'):format(text)
+  elseif node_name == 'h1' or node_name == 'h2' or node_name == 'h3' then
+    if is_noise(text, stats.noise_lines) then
+      return '' -- Discard common "noise" lines.
+    end
+    -- Remove tags from ToC text.
+    local heading_node = first(root, 'heading')
+    local hname = trim(node_text(heading_node):gsub('%*.*%*', ''))
+    if not heading_node or hname == '' then
+      return '' -- Spurious "===" or "---" in the help doc.
+    end
+
+    -- Generate an anchor id from the heading text.
+    local tagname = to_heading_tag(hname)
+    if node_name == 'h1' or #headings == 0 then
+      ---@type nvim.gen_help_html.heading
+      local heading = { name = hname, subheadings = {}, tag = tagname }
+      headings[#headings + 1] = heading
+    else
+      table.insert(
+        headings[#headings].subheadings,
+        { name = hname, subheadings = {}, tag = tagname }
+      )
+    end
+    local el = node_name == 'h1' and 'h2' or 'h3'
+    return ('<%s id="%s" class="help-heading">%s</%s>\n'):format(el, tagname, trimmed, el)
+  elseif node_name == 'heading' then
+    return trimmed
+  elseif node_name == 'column_heading' or node_name == 'column_name' then
+    if root:has_error() then
+      return text
+    end
+    return ('<div class="help-column_heading">%s</div>'):format(text)
+  elseif node_name == 'block' then
+    if is_blank(text) then
+      return ''
+    end
+    if opt.old then
+      -- XXX: Treat "old" docs as preformatted: they use indentation for layout.
+      --      Trim trailing newlines to avoid too much whitespace between divs.
+      return ('<div class="old-help-para">%s</div>\n'):format(trim(text, 2))
+    end
+    return string.format('<div class="help-para">\n%s\n</div>\n', text)
+  elseif node_name == 'line' then
+    if
+      (parent ~= 'codeblock' or parent ~= 'code')
+      and (is_blank(text) or is_noise(text, stats.noise_lines))
+    then
+      return '' -- Discard common "noise" lines.
+    end
+    -- XXX: Avoid newlines (too much whitespace) after block elements in old (preformatted) layout.
+    local div = opt.old
+      and root:child(0)
+      and vim.list_contains({ 'column_heading', 'h1', 'h2', 'h3' }, root:child(0):type())
+    return string.format('%s%s', div and trim(text) or text, div and '' or '\n')
+  elseif node_name == 'line_li' then
+    local sib = root:prev_sibling()
+    local prev_li = sib and sib:type() == 'line_li'
+
+    if not prev_li then
+      opt.indent = 1
+    else
+      -- The previous listitem _sibling_ is _logically_ the _parent_ if it is indented less.
+      local parent_indent = get_indent(node_text(sib))
+      local this_indent = get_indent(node_text())
+      if this_indent > parent_indent then
+        opt.indent = opt.indent + 1
+      elseif this_indent < parent_indent then
+        opt.indent = math.max(1, opt.indent - 1)
+      end
+    end
+    local margin = opt.indent == 1 and '' or ('margin-left: %drem;'):format((1.5 * opt.indent))
+
+    return string.format('<div class="help-li" style="%s">%s</div>', margin, text)
+  elseif node_name == 'taglink' or node_name == 'optionlink' then
+    local helppage, tagname, ignored = validate_link(root, opt.buf, opt.fname)
+    if ignored then
+      return text
+    end
+    local s = ('%s<a href="%s#%s">%s</a>'):format(
+      ws(),
+      helppage,
+      url_encode(tagname),
+      html_esc(tagname)
+    )
+    if opt.old and node_name == 'taglink' then
+      s = fix_tab_after_conceal(s, node_text(root:next_sibling()))
+    end
+    return s
+  elseif vim.list_contains({ 'codespan', 'keycode' }, node_name) then
+    if root:has_error() then
+      return text
+    end
+    local s = ('%s<code>%s</code>'):format(ws(), trimmed)
+    if opt.old and node_name == 'codespan' then
+      s = fix_tab_after_conceal(s, node_text(root:next_sibling()))
+    end
+    return s
+  elseif node_name == 'argument' then
+    return ('%s<code>{%s}</code>'):format(ws(), text)
+  elseif node_name == 'codeblock' then
+    return text
+  elseif node_name == 'language' then
+    language = node_text(root)
+    return ''
+  elseif node_name == 'code' then -- Highlighted codeblock (child).
+    if is_blank(text) then
+      return ''
+    end
+    local code ---@type string
+    if language then
+      code = ('<pre><code class="language-%s">%s</code></pre>'):format(
+        language,
+        trim(trim_indent(text), 2)
+      )
+      language = nil
+    else
+      code = ('<pre>%s</pre>'):format(trim(trim_indent(text), 2))
+    end
+    return code
+  elseif node_name == 'tag' then -- anchor, h4 pseudo-heading
+    if root:has_error() then
+      return text
+    end
+    local in_heading = vim.list_contains({ 'h1', 'h2', 'h3' }, parent)
+    local h4 = not in_heading and not next_ and get_indent(node_text()) > 8 -- h4 pseudo-heading
+    local cssclass = h4 and 'help-tag-right' or 'help-tag'
+    local tagname = node_text(root:child(1), false)
+    if vim.tbl_count(stats.first_tags) < 2 then
+      -- Force the first 2 tags in the doc to be anchored at the main heading.
+      table.insert(stats.first_tags, tagname)
+      return ''
+    end
+    local el = 'span'
+    local encoded_tagname = url_encode(tagname)
+    local s = ('%s<%s id="%s" class="%s"><a href="#%s">%s</a></%s>'):format(
+      ws(),
+      el,
+      encoded_tagname,
+      cssclass,
+      encoded_tagname,
+      trimmed,
+      el
+    )
+    if opt.old then
+      s = fix_tab_after_conceal(s, node_text(root:next_sibling()))
+    end
+
+    if in_heading and prev ~= 'tag' then
+      -- Start the <span> container for tags in a heading.
+      -- This makes "justify-content:space-between" right-align the tags.
+      --    <h2>foo bar<span>tag1 tag2</span></h2>
+      return string.format('<span class="help-heading-tags">%s', s)
+    elseif in_heading and next_ == nil then
+      -- End the <span> container for tags in a heading.
+      return string.format('%s</span>', s)
+    end
+    return s .. (h4 and '<br>' or '') -- HACK: <br> avoids h4 pseudo-heading mushing with text.
+  elseif node_name == 'delimiter' or node_name == 'modeline' then
+    return ''
+  elseif node_name == 'ERROR' then
+    if ignore_parse_error(opt.fname, trimmed) then
+      return text
+    end
+
+    -- Store the raw text to give context to the bug report.
+    local sample_text = level > 0 and getbuflinestr(root, opt.buf, 3) or '[top level!]'
+    table.insert(stats.parse_errors, sample_text)
+    return ('<a class="parse-error" target="_blank" title="Report bug... (parse error)" href="%s">%s</a>'):format(
+      get_bug_url_vimdoc(opt.fname, opt.to_fname, sample_text),
+      trimmed
+    )
+  else -- Unknown token.
+    local sample_text = level > 0 and getbuflinestr(root, opt.buf, 3) or '[top level!]'
+    return ('<a class="unknown-token" target="_blank" title="Report bug... (unhandled token "%s")" href="%s">%s</a>'):format(
+      node_name,
+      get_bug_url_nvim(opt.fname, opt.to_fname, sample_text, node_name),
+      trimmed
+    ),
+      ('unknown-token:"%s"'):format(node_name)
+  end
+end
+
+--- @param dir string e.g. '$VIMRUNTIME/doc'
+--- @param include string[]|nil
+--- @return string[]
+local function get_helpfiles(dir, include)
+  local rv = {}
+  for f, type in vim.fs.dir(dir) do
+    if
+      vim.endswith(f, '.txt')
+      and type == 'file'
+      and (not include or vim.list_contains(include, f))
+    then
+      local fullpath = vim.fn.fnamemodify(('%s/%s'):format(dir, f), ':p')
+      table.insert(rv, fullpath)
+    end
+  end
+  return rv
+end
+
+--- Populates the helptags map.
+local function get_helptags(help_dir)
+  local m = {}
+  -- Load a random help file to convince taglist() to do its job.
+  vim.cmd(string.format('split %s/api.txt', help_dir))
+  vim.cmd('lcd %:p:h')
+  for _, item in ipairs(vim.fn.taglist('.*')) do
+    if vim.endswith(item.filename, '.txt') then
+      m[item.name] = item.filename
+    end
+  end
+  vim.cmd('q!')
+  return m
+end
+
+--- Use the vimdoc parser defined in the build, not whatever happens to be installed on the system.
+local function ensure_runtimepath()
+  if not vim.o.runtimepath:find('build/lib/nvim/') then
+    vim.cmd [[set runtimepath^=./build/lib/nvim/]]
+  end
+end
+
+--- Opens `fname` (or `text`, if given) in a buffer and gets a treesitter parser for the buffer contents.
+---
+--- @param fname string :help file to parse
+--- @param text string? :help file contents
+--- @param parser_path string? path to non-default vimdoc.so
+--- @return vim.treesitter.LanguageTree, integer (lang_tree, bufnr)
+local function parse_buf(fname, text, parser_path)
+  local buf ---@type integer
+  if text then
+    vim.cmd('split new') -- Text contents.
+    vim.api.nvim_put(vim.split(text, '\n'), '', false, false)
+    vim.cmd('setfiletype help')
+    -- vim.treesitter.language.add('vimdoc')
+    buf = vim.api.nvim_get_current_buf()
+  elseif type(fname) == 'string' then
+    vim.cmd('split ' .. vim.fn.fnameescape(fname)) -- Filename.
+    buf = vim.api.nvim_get_current_buf()
+  else
+    -- Left for debugging
+    ---@diagnostic disable-next-line: no-unknown
+    buf = fname
+    vim.cmd('sbuffer ' .. tostring(fname)) -- Buffer number.
+  end
+  if parser_path then
+    vim.treesitter.language.add('vimdoc', { path = parser_path })
+  end
+  local lang_tree = assert(vim.treesitter.get_parser(buf, nil, { error = false }))
+  return lang_tree, buf
+end
+
+--- Validates one :help file `fname`:
+---  - checks that |tag| links point to valid helptags.
+---  - recursively counts parse errors ("ERROR" nodes)
+---
+--- @param fname string help file to validate
+--- @param parser_path string? path to non-default vimdoc.so
+--- @return { invalid_links: number, parse_errors: string[] }
+local function validate_one(fname, parser_path)
+  local stats = {
+    parse_errors = {},
+  }
+  local lang_tree, buf = parse_buf(fname, nil, parser_path)
+  for _, tree in ipairs(lang_tree:trees()) do
+    visit_validate(tree:root(), 0, tree, { buf = buf, fname = fname }, stats)
+  end
+  lang_tree:destroy()
+  vim.cmd.close()
+  return stats
+end
+
+--- Generates HTML from one :help file `fname` and writes the result to `to_fname`.
+---
+--- @param fname string Source :help file.
+--- @param text string|nil Source :help file contents, or nil to read `fname`.
+--- @param to_fname string Destination .html file
+--- @param old boolean Preformat paragraphs (for old :help files which are full of arbitrary whitespace)
+--- @param parser_path string? path to non-default vimdoc.so
+---
+--- @return string html
+--- @return table stats
+local function gen_one(fname, text, to_fname, old, commit, parser_path)
+  local stats = {
+    noise_lines = {},
+    parse_errors = {},
+    first_tags = {}, -- Track the first few tags in doc.
+  }
+  local lang_tree, buf = parse_buf(fname, text, parser_path)
+  ---@type nvim.gen_help_html.heading[]
+  local headings = {} -- Headings (for ToC). 2-dimensional: h1 contains h2/h3.
+  local title = to_titlecase(basename_noext(fname))
+
+  local html = ([[
+  <!DOCTYPE html>
+  <html>
+  <head>
+    <meta charset="utf-8">
+    <meta http-equiv="X-UA-Compatible" content="IE=edge">
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+    <meta name="description" content="Neovim user documentation">
+
+    <!-- algolia docsearch https://docsearch.algolia.com/docs/docsearch-v3/ -->
+    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@docsearch/css@3" />
+    <link rel="preconnect" href="https://X185E15FPG-dsn.algolia.net" crossorigin />
+
+    <link href="/css/bootstrap.min.css" rel="stylesheet">
+    <link href="/css/main.css" rel="stylesheet">
+    <link href="help.css" rel="stylesheet">
+    <link href="/highlight/styles/neovim.min.css" rel="stylesheet">
+
+    <script src="/highlight/highlight.min.js"></script>
+    <script>hljs.highlightAll();</script>
+    <title>%s - Neovim docs</title>
+  </head>
+  <body>
+  ]]):format(title)
+
+  local logo_svg = [[
+    <svg xmlns="http://www.w3.org/2000/svg" role="img" width="173" height="50" viewBox="0 0 742 214" aria-label="Neovim">
+      <title>Neovim</title>
+      <defs>
+        <linearGradient x1="50%" y1="0%" x2="50%" y2="100%" id="a">
+          <stop stop-color="#16B0ED" stop-opacity=".8" offset="0%" />
+          <stop stop-color="#0F59B2" stop-opacity=".837" offset="100%" />
+        </linearGradient>
+        <linearGradient x1="50%" y1="0%" x2="50%" y2="100%" id="b">
+          <stop stop-color="#7DB643" offset="0%" />
+          <stop stop-color="#367533" offset="100%" />
+        </linearGradient>
+        <linearGradient x1="50%" y1="0%" x2="50%" y2="100%" id="c">
+          <stop stop-color="#88C649" stop-opacity=".8" offset="0%" />
+          <stop stop-color="#439240" stop-opacity=".84" offset="100%" />
+        </linearGradient>
+      </defs>
+      <g fill="none" fill-rule="evenodd">
+        <path
+          d="M.027 45.459L45.224-.173v212.171L.027 166.894V45.459z"
+          fill="url(#a)"
+          transform="translate(1 1)"
+        />
+        <path
+          d="M129.337 45.89L175.152-.149l-.928 212.146-45.197-45.104.31-121.005z"
+          fill="url(#b)"
+          transform="matrix(-1 0 0 1 305 1)"
+        />
+        <path
+          d="M45.194-.137L162.7 179.173l-32.882 32.881L12.25 33.141 45.194-.137z"
+          fill="url(#c)"
+          transform="translate(1 1)"
+        />
+        <path
+          d="M46.234 84.032l-.063 7.063-36.28-53.563 3.36-3.422 32.983 49.922z"
+          fill-opacity=".13"
+          fill="#000"
+        />
+        <g fill="#444">
+          <path
+            d="M227 154V64.44h4.655c1.55 0 2.445.75 2.685 2.25l.806 13.502c4.058-5.16 8.786-9.316 14.188-12.466 5.4-3.15 11.413-4.726 18.037-4.726 4.893 0 9.205.781 12.935 2.34 3.729 1.561 6.817 3.811 9.264 6.751 2.448 2.942 4.297 6.48 5.55 10.621 1.253 4.14 1.88 8.821 1.88 14.042V154h-8.504V96.754c0-8.402-1.91-14.987-5.729-19.757-3.82-4.771-9.667-7.156-17.544-7.156-5.851 0-11.28 1.516-16.292 4.545-5.013 3.032-9.489 7.187-13.427 12.467V154H227zM350.624 63c5.066 0 9.755.868 14.069 2.605 4.312 1.738 8.052 4.268 11.219 7.592s5.638 7.412 7.419 12.264C385.11 90.313 386 95.883 386 102.17c0 1.318-.195 2.216-.588 2.696-.393.48-1.01.719-1.851.719h-64.966v1.70c0 6.708.784 12.609 2.353 17.7 1.567 5.09 3.8 9.357 6.695 12.802 2.895 3.445 6.393 6.034 10.495 7.771 4.1 1.738 8.686 2.606 13.752 2.606 4.524 0 8.446-.494 11.762-1.483 3.317-.988 6.108-2.097 8.37-3.324 2.261-1.227 4.056-2.336 5.383-3.324 1.326-.988 2.292-1.482 2.895-1.482.784 0 1.388.3 1.81.898l2.352 2.875c-1.448 1.797-3.362 3.475-5.745 5.031-2.383 1.558-5.038 2.891-7.962 3.998-2.926 1.109-6.062 1.991-9.41 2.65a52.21 52.21 0 01-10.088.989c-6.152 0-11.762-1.064-16.828-3.19-5.067-2.125-9.415-5.225-13.043-9.298-3.63-4.074-6.435-9.06-8.415-14.96C310.99 121.655 310 114.9 310 107.294c0-6.408.92-12.323 2.76-17.744 1.84-5.421 4.493-10.093 7.961-14.016 3.467-3.922 7.72-6.991 12.758-9.209C338.513 64.11 344.229 63 350.624 63zm.573 6c-4.696 0-8.904.702-12.623 2.105-3.721 1.404-6.936 3.421-9.65 6.053-2.713 2.631-4.908 5.79-6.586 9.474S319.55 94.439 319 99h60c0-4.679-.672-8.874-2.013-12.588-1.343-3.712-3.232-6.856-5.67-9.43-2.44-2.571-5.367-4.545-8.782-5.92-3.413-1.374-7.192-2.062-11.338-2.062zM435.546 63c6.526 0 12.368 1.093 17.524 3.28 5.154 2.186 9.5 5.286 13.04 9.298 3.538 4.013 6.238 8.85 8.099 14.51 1.861 5.66 2.791 11.994 2.791 19.002 0 7.008-.932 13.327-2.791 18.957-1.861 5.631-4.561 10.452-8.099 14.465-3.54 4.012-7.886 7.097-13.04 9.254-5.156 2.156-10.998 3.234-17.524 3.234-6.529 0-12.369-1.078-17.525-3.234-5.155-2.157-9.517-5.242-13.085-9.254-3.57-4.013-6.285-8.836-8.145-14.465-1.861-5.63-2.791-11.95-2.791-18.957 0-7.008.93-13.342 2.791-19.002 1.861-5.66 4.576-10.496 8.145-14.51 3.568-4.012 7.93-7.112 13.085-9.299C423.177 64.094 429.017 63 435.546 63zm-.501 86c5.341 0 10.006-.918 13.997-2.757 3.99-1.838 7.32-4.474 9.992-7.909 2.67-3.435 4.664-7.576 5.986-12.428 1.317-4.85 1.98-10.288 1.98-16.316 0-5.965-.66-11.389-1.98-16.27-1.322-4.88-3.316-9.053-5.986-12.519-2.67-3.463-6-6.13-9.992-7.999-3.991-1.867-8.657-2.802-13.997-2.802s-10.008.935-13.997 2.802c-3.991 1.87-7.322 4.536-9.992 8-2.671 3.465-4.68 7.637-6.03 12.518-1.35 4.881-2.026 10.305-2.026 16.27 0 6.026.675 11.465 2.025 16.316 1.35 4.852 3.36 8.993 6.031 12.428 2.67 3.435 6 6.07 9.992 7.91 3.99 1.838 8.656 2.756 13.997 2.756z"
+            fill="currentColor"
+          />
+          <path
+            d="M530.57 152h-20.05L474 60h18.35c1.61 0 2.967.39 4.072 1.166 1.103.778 1.865 1.763 2.283 2.959l17.722 49.138a92.762 92.762 0 012.551 8.429c.686 2.751 1.298 5.5 1.835 8.25.537-2.75 1.148-5.499 1.835-8.25a77.713 77.713 0 012.64-8.429l18.171-49.138c.417-1.196 1.164-2.181 2.238-2.96 1.074-.776 2.356-1.165 3.849-1.165H567l-36.43 92zM572 61h23v92h-23zM610 153V60.443h13.624c2.887 0 4.78 1.354 5.682 4.06l1.443 6.856a52.7 52.7 0 015.097-4.962 32.732 32.732 0 015.683-3.879 30.731 30.731 0 016.496-2.57c2.314-.632 4.855-.948 7.624-.948 5.832 0 10.63 1.579 14.39 4.736 3.758 3.157 6.57 7.352 8.434 12.585 1.444-3.068 3.248-5.698 5.413-7.894 2.165-2.194 4.541-3.984 7.127-5.367a32.848 32.848 0 018.254-3.068 39.597 39.597 0 018.796-.992c5.111 0 9.653.783 13.622 2.345 3.97 1.565 7.307 3.849 10.014 6.857 2.706 3.007 4.766 6.675 6.18 11.005C739.29 83.537 740 88.5 740 94.092V153h-22.284V94.092c0-5.894-1.294-10.329-3.878-13.306-2.587-2.977-6.376-4.465-11.368-4.465-2.286 0-4.404.391-6.358 1.172a15.189 15.189 0 00-5.144 3.383c-1.473 1.474-2.631 3.324-3.474 5.548-.842 2.225-1.263 4.781-1.263 7.668V153h-22.37V94.092c0-6.194-1.249-10.704-3.744-13.532-2.497-2.825-6.18-4.24-11.051-4.24-3.19 0-6.18.798-8.976 2.391-2.799 1.593-5.399 3.775-7.804 6.54V153H610zM572 30h23v19h-23z"
+            fill="currentColor"
+            fill-opacity=".8"
+          />
+        </g>
+      </g>
+    </svg>
+  ]]
+
+  local main = ''
+  for _, tree in ipairs(lang_tree:trees()) do
+    main = main
+      .. (
+        visit_node(
+          tree:root(),
+          0,
+          tree,
+          headings,
+          { buf = buf, old = old, fname = fname, to_fname = to_fname, indent = 1 },
+          stats
+        )
+      )
+  end
+
+  main = ([[
+  <header class="container">
+    <nav class="navbar navbar-expand-lg">
+      <div class="container-fluid">
+        <a href="/" class="navbar-brand" aria-label="logo">
+          <!--TODO: use <img src="….svg"> here instead. Need one that has green lettering instead of gray. -->
+          %s
+          <!--<img src="https://neovim.io/logos/neovim-logo.svg" width="173" height="50" alt="Neovim" />-->
+        </a>
+        <div id="docsearch"></div> <!-- algolia docsearch https://docsearch.algolia.com/docs/docsearch-v3/ -->
+      </div>
+    </nav>
+  </header>
+
+  <div class="container golden-grid help-body">
+  <div class="col-wide">
+  <a name="%s" href="#%s"><h1 id="%s">%s</h1></a>
+  <p>
+    <i>
+    Nvim <code>:help</code> pages, <a href="https://github.com/neovim/neovim/blob/master/scripts/gen_help_html.lua">generated</a>
+    from <a href="https://github.com/neovim/neovim/blob/master/runtime/doc/%s">source</a>
+    using the <a href="https://github.com/neovim/tree-sitter-vimdoc">tree-sitter-vimdoc</a> parser.
+    </i>
+  </p>
+  <hr/>
+  %s
+  </div>
+  ]]):format(
+    logo_svg,
+    stats.first_tags[1] or '',
+    stats.first_tags[2] or '',
+    stats.first_tags[2] or '',
+    title,
+    vim.fs.basename(fname),
+    main
+  )
+
+  ---@type string
+  local toc = [[
+    <div class="col-narrow toc">
+      <div><a href="index.html">Main</a></div>
+      <div><a href="vimindex.html">Commands index</a></div>
+      <div><a href="quickref.html">Quick reference</a></div>
+      <hr/>
+  ]]
+
+  local n = 0 -- Count of all headings + subheadings.
+  for _, h1 in ipairs(headings) do
+    n = n + 1 + #h1.subheadings
+  end
+  for _, h1 in ipairs(headings) do
+    ---@type string
+    toc = toc .. ('<div class="help-toc-h1"><a href="#%s">%s</a>\n'):format(h1.tag, h1.name)
+    if n < 30 or #headings < 10 then -- Show subheadings only if there aren't too many.
+      for _, h2 in ipairs(h1.subheadings) do
+        toc = toc
+          .. ('<div class="help-toc-h2"><a href="#%s">%s</a></div>\n'):format(h2.tag, h2.name)
+      end
+    end
+    toc = toc .. '</div>'
+  end
+  toc = toc .. '</div>\n'
+
+  local bug_url = get_bug_url_nvim(fname, to_fname, 'TODO', nil)
+  local bug_link = string.format('(<a href="%s" target="_blank">report docs bug...</a>)', bug_url)
+
+  local footer = ([[
+  <footer>
+    <div class="container flex">
+      <div class="generator-stats">
+        Generated at %s from <code><a href="https://github.com/neovim/neovim/commit/%s">%s</a></code>
+      </div>
+      <div class="generator-stats">
+      parse_errors: %d %s | <span title="%s">noise_lines: %d</span>
+      </div>
+    <div>
+
+    <!-- algolia docsearch https://docsearch.algolia.com/docs/docsearch-v3/ -->
+    <script src="https://cdn.jsdelivr.net/npm/@docsearch/js@3"></script>
+    <script type="module">
+      docsearch({
+        container: '#docsearch',
+        appId: 'X185E15FPG',
+        apiKey: 'b5e6b2f9c636b2b471303205e59832ed',
+        indexName: 'nvim',
+      });
+    </script>
+
+  </footer>
+  ]]):format(
+    os.date('%Y-%m-%d %H:%M'),
+    commit,
+    commit:sub(1, 7),
+    #stats.parse_errors,
+    bug_link,
+    html_esc(table.concat(stats.noise_lines, '\n')),
+    #stats.noise_lines
+  )
+
+  html = ('%s%s%s</div>\n%s</body>\n</html>\n'):format(html, main, toc, footer)
+  vim.cmd('q!')
+  lang_tree:destroy()
+  return html, stats
+end
+
+local function gen_css(fname)
+  local css = [[
+    :root {
+      --code-color: #004b4b;
+      --tag-color: #095943;
+    }
+    @media (prefers-color-scheme: dark) {
+      :root {
+        --code-color: #00c243;
+        --tag-color: #00b7b7;
+      }
+    }
+    @media (min-width: 40em) {
+      .toc {
+        position: fixed;
+        left: 67%;
+      }
+      .golden-grid {
+          display: grid;
+          grid-template-columns: 65% auto;
+          grid-gap: 1em;
+      }
+    }
+    @media (max-width: 40em) {
+      .golden-grid {
+        /* Disable grid for narrow viewport (mobile phone). */
+        display: block;
+      }
+    }
+    .toc {
+      /* max-width: 12rem; */
+      height: 85%;  /* Scroll if there are too many items. https://github.com/neovim/neovim.github.io/issues/297 */
+      overflow: auto;  /* Scroll if there are too many items. https://github.com/neovim/neovim.github.io/issues/297 */
+    }
+    .toc > div {
+      text-overflow: ellipsis;
+      overflow: hidden;
+      white-space: nowrap;
+    }
+    html {
+      scroll-behavior: auto;
+    }
+    body {
+      font-size: 18px;
+      line-height: 1.5;
+    }
+    h1, h2, h3, h4, h5 {
+      font-family: sans-serif;
+      border-bottom: 1px solid var(--tag-color); /*rgba(0, 0, 0, .9);*/
+    }
+    h3, h4, h5 {
+      border-bottom-style: dashed;
+    }
+    .help-column_heading {
+      color: var(--code-color);
+    }
+    .help-body {
+      padding-bottom: 2em;
+    }
+    .help-line {
+      /* font-family: ui-monospace,SFMono-Regular,SF Mono,Menlo,Consolas,Liberation Mono,monospace; */
+    }
+    .help-li {
+      white-space: normal;
+      display: list-item;
+      margin-left: 1.5rem; /* padding-left: 1rem; */
+    }
+    .help-para {
+      padding-top: 10px;
+      padding-bottom: 10px;
+    }
+
+    .old-help-para {
+      padding-top: 10px;
+      padding-bottom: 10px;
+      /* Tabs are used for alignment in old docs, so we must match Vim's 8-char expectation. */
+      tab-size: 8;
+      white-space: pre-wrap;
+      font-size: 16px;
+      font-family: ui-monospace,SFMono-Regular,SF Mono,Menlo,Consolas,Liberation Mono,monospace;
+      word-wrap: break-word;
+    }
+    .old-help-para pre, .old-help-para pre:hover {
+      /* Text following <pre> is already visually separated by the linebreak. */
+      margin-bottom: 0;
+      /* Long lines that exceed the textwidth should not be wrapped (no "pre-wrap").
+         Since text may overflow horizontally, we make the contents to be scrollable
+         (only if necessary) to prevent overlapping with the navigation bar at the right. */
+      white-space: pre;
+      overflow-x: auto;
+    }
+
+    /* TODO: should this rule be deleted? help tags are rendered as <code> or <span>, not <a> */
+    a.help-tag, a.help-tag:focus, a.help-tag:hover {
+      color: inherit;
+      text-decoration: none;
+    }
+    .help-tag {
+      color: var(--tag-color);
+    }
+    /* Tag pseudo-header common in :help docs. */
+    .help-tag-right {
+      color: var(--tag-color);
+      margin-left: auto;
+      margin-right: 0;
+      float: right;
+      display: block;
+    }
+    .help-tag a,
+    .help-tag-right a {
+      color: inherit;
+    }
+    .help-tag a:not(:hover),
+    .help-tag-right a:not(:hover) {
+      text-decoration: none;
+    }
+    h1 .help-tag, h2 .help-tag, h3 .help-tag {
+      font-size: smaller;
+    }
+    .help-heading {
+      white-space: normal;
+      display: flex;
+      flex-flow: row wrap;
+      justify-content: space-between;
+      gap: 0 15px;
+    }
+    /* The (right-aligned) "tags" part of a section heading. */
+    .help-heading-tags {
+      margin-right: 10px;
+    }
+    .help-toc-h1 {
+    }
+    .help-toc-h2 {
+      margin-left: 1em;
+    }
+    .parse-error {
+      background-color: red;
+    }
+    .unknown-token {
+      color: black;
+      background-color: yellow;
+    }
+    code {
+      color: var(--code-color);
+      font-size: 16px;
+    }
+    pre {
+      /* Tabs are used in codeblocks only for indentation, not alignment, so we can aggressively shrink them. */
+      tab-size: 2;
+      white-space: pre-wrap;
+      line-height: 1.3;  /* Important for ascii art. */
+      overflow: visible;
+      /* font-family: ui-monospace,SFMono-Regular,SF Mono,Menlo,Consolas,Liberation Mono,monospace; */
+      font-size: 16px;
+      margin-top: 10px;
+    }
+    pre:last-child {
+      margin-bottom: 0;
+    }
+    pre:hover {
+      overflow: visible;
+    }
+    .generator-stats {
+      color: gray;
+      font-size: smaller;
+    }
+  ]]
+  tofile(fname, css)
+end
+
+-- Testing
+
+local function ok(cond, expected, actual, message)
+  assert(
+    (not expected and not actual) or (expected and actual),
+    'if "expected" is given, "actual" is also required'
+  )
+  if expected then
+    assert(
+      cond,
+      ('%sexpected %s, got: %s'):format(
+        message and (message .. '\n') or '',
+        vim.inspect(expected),
+        vim.inspect(actual)
+      )
+    )
+    return cond
+  else
+    return assert(cond)
+  end
+end
+local function eq(expected, actual, message)
+  return ok(vim.deep_equal(expected, actual), expected, actual, message)
+end
+
+function M._test()
+  tagmap = get_helptags('$VIMRUNTIME/doc')
+  helpfiles = get_helpfiles(vim.fs.normalize('$VIMRUNTIME/doc'))
+
+  ok(vim.tbl_count(tagmap) > 3000, '>3000', vim.tbl_count(tagmap))
+  ok(
+    vim.endswith(tagmap['vim.diagnostic.set()'], 'diagnostic.txt'),
+    tagmap['vim.diagnostic.set()'],
+    'diagnostic.txt'
+  )
+  ok(vim.endswith(tagmap['%:s'], 'cmdline.txt'), tagmap['%:s'], 'cmdline.txt')
+  ok(is_noise([[vim:tw=78:isk=!-~,^*,^\|,^\":ts=8:noet:ft=help:norl:]]))
+  ok(is_noise([[          NVIM  REFERENCE  MANUAL     by  Thiago  de  Arruda      ]]))
+  ok(not is_noise([[vim:tw=78]]))
+
+  eq(0, get_indent('a'))
+  eq(1, get_indent(' a'))
+  eq(2, get_indent('  a\n  b\n  c\n'))
+  eq(5, get_indent('     a\n      \n        b\n      c\n      d\n      e\n'))
+  eq(
+    'a\n        \n   b\n c\n d\n e\n',
+    trim_indent('     a\n             \n        b\n      c\n      d\n      e\n')
+  )
+
+  local fixed_url, removed_chars = fix_url('https://example.com).')
+  eq('https://example.com', fixed_url)
+  eq(').', removed_chars)
+  fixed_url, removed_chars = fix_url('https://example.com.)')
+  eq('https://example.com.', fixed_url)
+  eq(')', removed_chars)
+  fixed_url, removed_chars = fix_url('https://example.com.')
+  eq('https://example.com', fixed_url)
+  eq('.', removed_chars)
+  fixed_url, removed_chars = fix_url('https://example.com)')
+  eq('https://example.com', fixed_url)
+  eq(')', removed_chars)
+  fixed_url, removed_chars = fix_url('https://example.com')
+  eq('https://example.com', fixed_url)
+  eq('', removed_chars)
+
+  print('all tests passed.\n')
+end
+
+--- @class nvim.gen_help_html.gen_result
+--- @field helpfiles string[] list of generated HTML files, from the source docs {include}
+--- @field err_count integer number of parse errors in :help docs
+--- @field invalid_links table<string, any>
+
+--- Generates HTML from :help docs located in `help_dir` and writes the result in `to_dir`.
+---
+--- Example:
+---
+---   gen('$VIMRUNTIME/doc', '/path/to/neovim.github.io/_site/doc/', {'api.txt', 'autocmd.txt', 'channel.txt'}, nil)
+---
+--- @param help_dir string Source directory containing the :help files. Must run `make helptags` first.
+--- @param to_dir string Target directory where the .html files will be written.
+--- @param include string[]|nil Process only these filenames. Example: {'api.txt', 'autocmd.txt', 'channel.txt'}
+---
+--- @return nvim.gen_help_html.gen_result result
+function M.gen(help_dir, to_dir, include, commit, parser_path)
+  vim.validate('help_dir', help_dir, function(d)
+    return vim.fn.isdirectory(vim.fs.normalize(d)) == 1
+  end, 'valid directory')
+  vim.validate('to_dir', to_dir, 'string')
+  vim.validate('include', include, 'table', true)
+  vim.validate('commit', commit, 'string', true)
+  vim.validate('parser_path', parser_path, function(f)
+    return vim.fn.filereadable(vim.fs.normalize(f)) == 1
+  end, true, 'valid vimdoc.{so,dll} filepath')
+
+  local err_count = 0
+  local redirects_count = 0
+  ensure_runtimepath()
+  tagmap = get_helptags(vim.fs.normalize(help_dir))
+  helpfiles = get_helpfiles(help_dir, include)
+  to_dir = vim.fs.normalize(to_dir)
+  parser_path = parser_path and vim.fs.normalize(parser_path) or nil
+
+  print(('output dir: %s\n\n'):format(to_dir))
+  vim.fn.mkdir(to_dir, 'p')
+  gen_css(('%s/help.css'):format(to_dir))
+
+  for _, f in ipairs(helpfiles) do
+    -- "foo.txt"
+    local helpfile = vim.fs.basename(f)
+    -- "to/dir/foo.html"
+    local to_fname = ('%s/%s'):format(to_dir, get_helppage(helpfile))
+    local html, stats =
+      gen_one(f, nil, to_fname, not new_layout[helpfile], commit or '?', parser_path)
+    tofile(to_fname, html)
+    print(
+      ('generated (%-2s errors): %-15s => %s'):format(
+        #stats.parse_errors,
+        helpfile,
+        vim.fs.basename(to_fname)
+      )
+    )
+
+    -- Generate redirect pages for renamed help files.
+    local helpfile_tag = (helpfile:gsub('%.txt$', ''))
+    local redirect_from = redirects[helpfile_tag]
+    if redirect_from then
+      local redirect_text = ([[
+*%s*      Nvim
+
+This document moved to: |%s|
+
+==============================================================================
+This document moved to: |%s|
+
+This document moved to: |%s|
+
+==============================================================================
+ vim:tw=78:ts=8:ft=help:norl:
+      ]]):format(
+        redirect_from,
+        helpfile_tag,
+        helpfile_tag,
+        helpfile_tag,
+        helpfile_tag,
+        helpfile_tag
+      )
+      local redirect_to = ('%s/%s'):format(to_dir, get_helppage(redirect_from))
+      local redirect_html, _ =
+        gen_one(redirect_from, redirect_text, redirect_to, false, commit or '?', parser_path)
+      assert(redirect_html:find(helpfile_tag))
+      tofile(redirect_to, redirect_html)
+
+      print(
+        ('generated (redirect) : %-15s => %s'):format(
+          redirect_from .. '.txt',
+          vim.fs.basename(to_fname)
+        )
+      )
+      redirects_count = redirects_count + 1
+    end
+
+    err_count = err_count + #stats.parse_errors
+  end
+
+  print(('\ngenerated %d html pages'):format(#helpfiles + redirects_count))
+  print(('total errors: %d'):format(err_count))
+  print(('invalid tags: %s'):format(vim.inspect(invalid_links)))
+  assert(#(include or {}) > 0 or redirects_count == vim.tbl_count(redirects)) -- sanity check
+  print(('redirects: %d'):format(redirects_count))
+  print('\n')
+
+  --- @type nvim.gen_help_html.gen_result
+  return {
+    helpfiles = helpfiles,
+    err_count = err_count,
+    invalid_links = invalid_links,
+  }
+end
+
+--- @class nvim.gen_help_html.validate_result
+--- @field helpfiles integer number of generated helpfiles
+--- @field err_count integer number of parse errors
+--- @field parse_errors table<string, string[]>
+--- @field invalid_links table<string, any> invalid tags in :help docs
+--- @field invalid_urls table<string, any> invalid URLs in :help docs
+--- @field invalid_spelling table<string, table<string, string>> invalid spelling in :help docs
+
+--- Validates all :help files found in `help_dir`:
+---  - checks that |tag| links point to valid helptags.
+---  - recursively counts parse errors ("ERROR" nodes)
+---
+--- This is 10x faster than gen(), for use in CI.
+---
+--- @return nvim.gen_help_html.validate_result result
+function M.validate(help_dir, include, parser_path)
+  vim.validate('help_dir', help_dir, function(d)
+    return vim.fn.isdirectory(vim.fs.normalize(d)) == 1
+  end, 'valid directory')
+  vim.validate('include', include, 'table', true)
+  vim.validate('parser_path', parser_path, function(f)
+    return vim.fn.filereadable(vim.fs.normalize(f)) == 1
+  end, true, 'valid vimdoc.{so,dll} filepath')
+  local err_count = 0 ---@type integer
+  local files_to_errors = {} ---@type table<string, string[]>
+  ensure_runtimepath()
+  tagmap = get_helptags(vim.fs.normalize(help_dir))
+  helpfiles = get_helpfiles(help_dir, include)
+  parser_path = parser_path and vim.fs.normalize(parser_path) or nil
+
+  for _, f in ipairs(helpfiles) do
+    local helpfile = vim.fs.basename(f)
+    local rv = validate_one(f, parser_path)
+    print(('validated (%-4s errors): %s'):format(#rv.parse_errors, helpfile))
+    if #rv.parse_errors > 0 then
+      files_to_errors[helpfile] = rv.parse_errors
+      vim.print(('%s'):format(vim.iter(rv.parse_errors):fold('', function(s, v)
+        return s .. '\n    ' .. v
+      end)))
+    end
+    err_count = err_count + #rv.parse_errors
+  end
+
+  ---@type nvim.gen_help_html.validate_result
+  return {
+    helpfiles = #helpfiles,
+    err_count = err_count,
+    parse_errors = files_to_errors,
+    invalid_links = invalid_links,
+    invalid_urls = invalid_urls,
+    invalid_spelling = invalid_spelling,
+  }
+end
+
+--- Validates vimdoc files on $VIMRUNTIME. and print human-readable error messages if fails.
+---
+--- If this fails, try these steps (in order):
+--- 1. Fix/cleanup the :help docs.
+--- 2. Fix the parser: https://github.com/neovim/tree-sitter-vimdoc
+--- 3. File a parser bug, and adjust the tolerance of this test in the meantime.
+---
+--- @param help_dir? string e.g. '$VIMRUNTIME/doc' or './runtime/doc'
+function M.run_validate(help_dir)
+  help_dir = vim.fs.normalize(help_dir or '$VIMRUNTIME/doc')
+  print('doc path = ' .. vim.uv.fs_realpath(help_dir))
+
+  local rv = M.validate(help_dir)
+
+  -- Check that we actually found helpfiles.
+  ok(rv.helpfiles > 100, '>100 :help files', rv.helpfiles)
+
+  eq({}, rv.parse_errors, 'no parse errors')
+  eq(0, rv.err_count, 'no parse errors')
+  eq({}, rv.invalid_links, 'invalid tags in :help docs')
+  eq({}, rv.invalid_urls, 'invalid URLs in :help docs')
+  eq(
+    {},
+    rv.invalid_spelling,
+    'invalid spelling in :help docs (see spell_dict in scripts/gen_help_html.lua)'
+  )
+end
+
+--- Test-generates HTML from docs.
+---
+--- 1. Test that gen_help_html.lua actually works.
+--- 2. Test that parse errors did not increase wildly. Because we explicitly test only a few
+---    :help files, we can be precise about the tolerances here.
+--- @param help_dir? string e.g. '$VIMRUNTIME/doc' or './runtime/doc'
+function M.test_gen(help_dir)
+  local tmpdir = vim.fs.dirname(vim.fn.tempname())
+  help_dir = vim.fs.normalize(help_dir or '$VIMRUNTIME/doc')
+  print('doc path = ' .. vim.uv.fs_realpath(help_dir))
+
+  -- Because gen() is slow (~30s), this test is limited to a few files.
+  local input = { 'help.txt', 'index.txt', 'nvim.txt' }
+  local rv = M.gen(help_dir, tmpdir, input)
+  eq(#input, #rv.helpfiles)
+  eq(0, rv.err_count, 'parse errors in :help docs')
+  eq({}, rv.invalid_links, 'invalid tags in :help docs')
+end
+
+return M
diff --git a/src/gen/gen_lsp.lua b/src/gen/gen_lsp.lua
new file mode 100644
index 0000000000..38792307e4
--- /dev/null
+++ b/src/gen/gen_lsp.lua
@@ -0,0 +1,514 @@
+-- Generates lua-ls annotations for lsp.
+
+local USAGE = [[
+Generates lua-ls annotations for lsp.
+
+USAGE:
+nvim -l src/gen/gen_lsp.lua gen  # by default, this will overwrite runtime/lua/vim/lsp/_meta/protocol.lua
+nvim -l src/gen/gen_lsp.lua gen --version 3.18 --out runtime/lua/vim/lsp/_meta/protocol.lua
+nvim -l src/gen/gen_lsp.lua gen --version 3.18 --methods --capabilities
+]]
+
+local DEFAULT_LSP_VERSION = '3.18'
+
+local M = {}
+
+local function tofile(fname, text)
+  local f = io.open(fname, 'w')
+  if not f then
+    error(('failed to write: %s'):format(f))
+  else
+    print(('Written to: %s'):format(fname))
+    f:write(text)
+    f:close()
+  end
+end
+
+--- The LSP protocol JSON data (it's partial, non-exhaustive).
+--- https://raw.githubusercontent.com/microsoft/language-server-protocol/gh-pages/_specifications/lsp/3.18/metaModel/metaModel.schema.json
+--- @class vim._gen_lsp.Protocol
+--- @field requests vim._gen_lsp.Request[]
+--- @field notifications vim._gen_lsp.Notification[]
+--- @field structures vim._gen_lsp.Structure[]
+--- @field enumerations vim._gen_lsp.Enumeration[]
+--- @field typeAliases vim._gen_lsp.TypeAlias[]
+
+---@param opt vim._gen_lsp.opt
+---@return vim._gen_lsp.Protocol
+local function read_json(opt)
+  local uri = 'https://raw.githubusercontent.com/microsoft/language-server-protocol/gh-pages/_specifications/lsp/'
+    .. opt.version
+    .. '/metaModel/metaModel.json'
+  print('Reading ' .. uri)
+
+  local res = vim.system({ 'curl', '--no-progress-meter', uri, '-o', '-' }):wait()
+  if res.code ~= 0 or (res.stdout or ''):len() < 999 then
+    print(('URL failed: %s'):format(uri))
+    vim.print(res)
+    error(res.stdout)
+  end
+  return vim.json.decode(res.stdout)
+end
+
+-- Gets the Lua symbol for a given fully-qualified LSP method name.
+local function to_luaname(s)
+  -- "$/" prefix is special: https://microsoft.github.io/language-server-protocol/specification/#dollarRequests
+  return s:gsub('^%$', 'dollar'):gsub('/', '_')
+end
+
+---@param protocol vim._gen_lsp.Protocol
+---@param gen_methods boolean
+---@param gen_capabilities boolean
+local function write_to_protocol(protocol, gen_methods, gen_capabilities)
+  if not gen_methods and not gen_capabilities then
+    return
+  end
+
+  local indent = (' '):rep(2)
+
+  --- @class vim._gen_lsp.Request
+  --- @field deprecated? string
+  --- @field documentation? string
+  --- @field messageDirection string
+  --- @field clientCapability? string
+  --- @field serverCapability? string
+  --- @field method string
+  --- @field params? any
+  --- @field proposed? boolean
+  --- @field registrationMethod? string
+  --- @field registrationOptions? any
+  --- @field since? string
+
+  --- @class vim._gen_lsp.Notification
+  --- @field deprecated? string
+  --- @field documentation? string
+  --- @field errorData? any
+  --- @field messageDirection string
+  --- @field clientCapability? string
+  --- @field serverCapability? string
+  --- @field method string
+  --- @field params? any[]
+  --- @field partialResult? any
+  --- @field proposed? boolean
+  --- @field registrationMethod? string
+  --- @field registrationOptions? any
+  --- @field result any
+  --- @field since? string
+
+  ---@type (vim._gen_lsp.Request|vim._gen_lsp.Notification)[]
+  local all = vim.list_extend(protocol.requests, protocol.notifications)
+  table.sort(all, function(a, b)
+    return to_luaname(a.method) < to_luaname(b.method)
+  end)
+
+  local output = { '-- Generated by gen_lsp.lua, keep at end of file.' }
+
+  if gen_methods then
+    output[#output + 1] = '--- @alias vim.lsp.protocol.Method.ClientToServer'
+
+    for _, item in ipairs(all) do
+      if item.method and item.messageDirection == 'clientToServer' then
+        output[#output + 1] = ("--- | '%s',"):format(item.method)
+      end
+    end
+
+    vim.list_extend(output, {
+      '',
+      '--- @alias vim.lsp.protocol.Method.ServerToClient',
+    })
+    for _, item in ipairs(all) do
+      if item.method and item.messageDirection == 'serverToClient' then
+        output[#output + 1] = ("--- | '%s',"):format(item.method)
+      end
+    end
+
+    vim.list_extend(output, {
+      '',
+      '--- @alias vim.lsp.protocol.Method',
+      '--- | vim.lsp.protocol.Method.ClientToServer',
+      '--- | vim.lsp.protocol.Method.ServerToClient',
+      '',
+      '-- Generated by gen_lsp.lua, keep at end of file.',
+      '--- @enum vim.lsp.protocol.Methods',
+      '--- @see https://microsoft.github.io/language-server-protocol/specification/#metaModel',
+      '--- LSP method names.',
+      'protocol.Methods = {',
+    })
+
+    for _, item in ipairs(all) do
+      if item.method then
+        if item.documentation then
+          local document = vim.split(item.documentation, '\n?\n', { trimempty = true })
+          for _, docstring in ipairs(document) do
+            output[#output + 1] = indent .. '--- ' .. docstring
+          end
+        end
+        output[#output + 1] = ("%s%s = '%s',"):format(indent, to_luaname(item.method), item.method)
+      end
+    end
+    output[#output + 1] = '}'
+  end
+
+  if gen_capabilities then
+    vim.list_extend(output, {
+      '',
+      '-- stylua: ignore start',
+      '-- Generated by gen_lsp.lua, keep at end of file.',
+      '--- Maps method names to the required server capability',
+      'protocol._request_name_to_capability = {',
+    })
+
+    for _, item in ipairs(all) do
+      if item.serverCapability then
+        output[#output + 1] = ("%s['%s'] = { %s },"):format(
+          indent,
+          item.method,
+          table.concat(
+            vim
+              .iter(vim.split(item.serverCapability, '.', { plain = true }))
+              :map(function(segment)
+                return "'" .. segment .. "'"
+              end)
+              :totable(),
+            ', '
+          )
+        )
+      end
+    end
+
+    output[#output + 1] = '}'
+    output[#output + 1] = '-- stylua: ignore end'
+  end
+
+  output[#output + 1] = ''
+  output[#output + 1] = 'return protocol'
+
+  local fname = './runtime/lua/vim/lsp/protocol.lua'
+  local bufnr = vim.fn.bufadd(fname)
+  vim.fn.bufload(bufnr)
+  vim.api.nvim_set_current_buf(bufnr)
+  local lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
+  local index = vim.iter(ipairs(lines)):find(function(key, item)
+    return vim.startswith(item, '-- Generated by') and key or nil
+  end)
+  index = index and index - 1 or vim.api.nvim_buf_line_count(bufnr) - 1
+  vim.api.nvim_buf_set_lines(bufnr, index, -1, true, output)
+  vim.cmd.write()
+end
+
+---@class vim._gen_lsp.opt
+---@field output_file string
+---@field version string
+---@field methods boolean
+---@field capabilities boolean
+
+---@param opt vim._gen_lsp.opt
+function M.gen(opt)
+  --- @type vim._gen_lsp.Protocol
+  local protocol = read_json(opt)
+
+  write_to_protocol(protocol, opt.methods, opt.capabilities)
+
+  local output = {
+    '--' .. '[[',
+    'THIS FILE IS GENERATED by scr/gen/gen_lsp.lua',
+    'DO NOT EDIT MANUALLY',
+    '',
+    'Based on LSP protocol ' .. opt.version,
+    '',
+    'Regenerate:',
+    ([=[nvim -l scr/gen/gen_lsp.lua gen --version %s]=]):format(DEFAULT_LSP_VERSION),
+    '--' .. ']]',
+    '',
+    '---@meta',
+    "error('Cannot require a meta file')",
+    '',
+    '---@alias lsp.null nil',
+    '---@alias uinteger integer',
+    '---@alias decimal number',
+    '---@alias lsp.DocumentUri string',
+    '---@alias lsp.URI string',
+    '',
+  }
+
+  local anonymous_num = 0
+
+  ---@type string[]
+  local anonym_classes = {}
+
+  local simple_types = {
+    'string',
+    'boolean',
+    'integer',
+    'uinteger',
+    'decimal',
+  }
+
+  ---@param documentation string
+  local _process_documentation = function(documentation)
+    documentation = documentation:gsub('\n', '\n---')
+    -- Remove <200b> (zero-width space) unicode characters: e.g., `**/<200b>*`
+    documentation = documentation:gsub('\226\128\139', '')
+    -- Escape annotations that are not recognized by lua-ls
+    documentation = documentation:gsub('%^---@sample', '---\\@sample')
+    return '---' .. documentation
+  end
+
+  --- @class vim._gen_lsp.Type
+  --- @field kind string a common field for all Types.
+  --- @field name? string for ReferenceType, BaseType
+  --- @field element? any for ArrayType
+  --- @field items? vim._gen_lsp.Type[] for OrType, AndType
+  --- @field key? vim._gen_lsp.Type for MapType
+  --- @field value? string|vim._gen_lsp.Type for StringLiteralType, MapType, StructureLiteralType
+
+  ---@param type vim._gen_lsp.Type
+  ---@param prefix? string Optional prefix associated with the this type, made of (nested) field name.
+  ---             Used to generate class name for structure literal types.
+  ---@return string
+  local function parse_type(type, prefix)
+    -- ReferenceType | BaseType
+    if type.kind == 'reference' or type.kind == 'base' then
+      if vim.tbl_contains(simple_types, type.name) then
+        return type.name
+      end
+      return 'lsp.' .. type.name
+
+    -- ArrayType
+    elseif type.kind == 'array' then
+      local parsed_items = parse_type(type.element, prefix)
+      if type.element.items and #type.element.items > 1 then
+        parsed_items = '(' .. parsed_items .. ')'
+      end
+      return parsed_items .. '[]'
+
+    -- OrType
+    elseif type.kind == 'or' then
+      local val = ''
+      for _, item in ipairs(type.items) do
+        val = val .. parse_type(item, prefix) .. '|' --[[ @as string ]]
+      end
+      val = val:sub(0, -2)
+      return val
+
+    -- StringLiteralType
+    elseif type.kind == 'stringLiteral' then
+      return '"' .. type.value .. '"'
+
+    -- MapType
+    elseif type.kind == 'map' then
+      local key = assert(type.key)
+      local value = type.value --[[ @as vim._gen_lsp.Type ]]
+      return 'table<' .. parse_type(key, prefix) .. ', ' .. parse_type(value, prefix) .. '>'
+
+    -- StructureLiteralType
+    elseif type.kind == 'literal' then
+      -- can I use ---@param disabled? {reason: string}
+      -- use | to continue the inline class to be able to add docs
+      -- https://github.com/LuaLS/lua-language-server/issues/2128
+      anonymous_num = anonymous_num + 1
+      local anonymous_classname = 'lsp._anonym' .. anonymous_num
+      if prefix then
+        anonymous_classname = anonymous_classname .. '.' .. prefix
+      end
+      local anonym = vim
+        .iter({
+          (anonymous_num > 1 and { '' } or {}),
+          { '---@class ' .. anonymous_classname },
+        })
+        :flatten()
+        :totable()
+
+      --- @class vim._gen_lsp.StructureLiteral translated to anonymous @class.
+      --- @field deprecated? string
+      --- @field description? string
+      --- @field properties vim._gen_lsp.Property[]
+      --- @field proposed? boolean
+      --- @field since? string
+
+      ---@type vim._gen_lsp.StructureLiteral
+      local structural_literal = assert(type.value) --[[ @as vim._gen_lsp.StructureLiteral ]]
+      for _, field in ipairs(structural_literal.properties) do
+        anonym[#anonym + 1] = '---'
+        if field.documentation then
+          anonym[#anonym + 1] = _process_documentation(field.documentation)
+        end
+        anonym[#anonym + 1] = '---@field '
+          .. field.name
+          .. (field.optional and '?' or '')
+          .. ' '
+          .. parse_type(field.type, prefix .. '.' .. field.name)
+      end
+      -- anonym[#anonym + 1] = ''
+      for _, line in ipairs(anonym) do
+        if line then
+          anonym_classes[#anonym_classes + 1] = line
+        end
+      end
+      return anonymous_classname
+
+    -- TupleType
+    elseif type.kind == 'tuple' then
+      local tuple = '['
+      for _, value in ipairs(type.items) do
+        tuple = tuple .. parse_type(value, prefix) .. ', '
+      end
+      -- remove , at the end
+      tuple = tuple:sub(0, -3)
+      return tuple .. ']'
+    end
+
+    vim.print('WARNING: Unknown type ', type)
+    return ''
+  end
+
+  --- @class vim._gen_lsp.Structure translated to @class
+  --- @field deprecated? string
+  --- @field documentation? string
+  --- @field extends? { kind: string, name: string }[]
+  --- @field mixins? { kind: string, name: string }[]
+  --- @field name string
+  --- @field properties? vim._gen_lsp.Property[]  members, translated to @field
+  --- @field proposed? boolean
+  --- @field since? string
+  for _, structure in ipairs(protocol.structures) do
+    -- output[#output + 1] = ''
+    if structure.documentation then
+      output[#output + 1] = _process_documentation(structure.documentation)
+    end
+    local class_string = ('---@class lsp.%s'):format(structure.name)
+    if structure.extends or structure.mixins then
+      local inherits_from = table.concat(
+        vim.list_extend(
+          vim.tbl_map(parse_type, structure.extends or {}),
+          vim.tbl_map(parse_type, structure.mixins or {})
+        ),
+        ', '
+      )
+      class_string = class_string .. ': ' .. inherits_from
+    end
+    output[#output + 1] = class_string
+
+    --- @class vim._gen_lsp.Property translated to @field
+    --- @field deprecated? string
+    --- @field documentation? string
+    --- @field name string
+    --- @field optional? boolean
+    --- @field proposed? boolean
+    --- @field since? string
+    --- @field type { kind: string, name: string }
+    for _, field in ipairs(structure.properties or {}) do
+      output[#output + 1] = '---' -- Insert a single newline between @fields (and after @class)
+      if field.documentation then
+        output[#output + 1] = _process_documentation(field.documentation)
+      end
+      output[#output + 1] = '---@field '
+        .. field.name
+        .. (field.optional and '?' or '')
+        .. ' '
+        .. parse_type(field.type, field.name)
+    end
+    output[#output + 1] = ''
+  end
+
+  --- @class vim._gen_lsp.Enumeration translated to @enum
+  --- @field deprecated string?
+  --- @field documentation string?
+  --- @field name string?
+  --- @field proposed boolean?
+  --- @field since string?
+  --- @field suportsCustomValues boolean?
+  --- @field values { name: string, value: string, documentation?: string, since?: string }[]
+  for _, enum in ipairs(protocol.enumerations) do
+    if enum.documentation then
+      output[#output + 1] = _process_documentation(enum.documentation)
+    end
+    local enum_type = '---@alias lsp.' .. enum.name
+    for _, value in ipairs(enum.values) do
+      enum_type = enum_type
+        .. '\n---| '
+        .. (type(value.value) == 'string' and '"' .. value.value .. '"' or value.value)
+        .. ' # '
+        .. value.name
+    end
+    output[#output + 1] = enum_type
+    output[#output + 1] = ''
+  end
+
+  --- @class vim._gen_lsp.TypeAlias translated to @alias
+  --- @field deprecated? string?
+  --- @field documentation? string
+  --- @field name string
+  --- @field proposed? boolean
+  --- @field since? string
+  --- @field type vim._gen_lsp.Type
+  for _, alias in ipairs(protocol.typeAliases) do
+    if alias.documentation then
+      output[#output + 1] = _process_documentation(alias.documentation)
+    end
+    if alias.type.kind == 'or' then
+      local alias_type = '---@alias lsp.' .. alias.name .. ' '
+      for _, item in ipairs(alias.type.items) do
+        alias_type = alias_type .. parse_type(item, alias.name) .. '|'
+      end
+      alias_type = alias_type:sub(0, -2)
+      output[#output + 1] = alias_type
+    else
+      output[#output + 1] = '---@alias lsp.'
+        .. alias.name
+        .. ' '
+        .. parse_type(alias.type, alias.name)
+    end
+    output[#output + 1] = ''
+  end
+
+  -- anonymous classes
+  for _, line in ipairs(anonym_classes) do
+    output[#output + 1] = line
+  end
+
+  tofile(opt.output_file, table.concat(output, '\n') .. '\n')
+end
+
+---@type vim._gen_lsp.opt
+local opt = {
+  output_file = 'runtime/lua/vim/lsp/_meta/protocol.lua',
+  version = DEFAULT_LSP_VERSION,
+  methods = false,
+  capabilities = false,
+}
+
+local command = nil
+local i = 1
+while i <= #_G.arg do
+  if _G.arg[i] == '--out' then
+    opt.output_file = assert(_G.arg[i + 1], '--out <outfile> needed')
+    i = i + 1
+  elseif _G.arg[i] == '--version' then
+    opt.version = assert(_G.arg[i + 1], '--version <version> needed')
+    i = i + 1
+  elseif _G.arg[i] == '--methods' then
+    opt.methods = true
+  elseif _G.arg[i] == '--capabilities' then
+    opt.capabilities = true
+  elseif vim.startswith(_G.arg[i], '-') then
+    error('Unrecognized args: ' .. _G.arg[i])
+  else
+    if command then
+      error('More than one command was given: ' .. _G.arg[i])
+    else
+      command = _G.arg[i]
+    end
+  end
+  i = i + 1
+end
+
+if not command then
+  print(USAGE)
+elseif M[command] then
+  M[command](opt) -- see M.gen()
+else
+  error('Unknown command: ' .. command)
+end
+
+return M
diff --git a/src/gen/gen_options.lua b/src/gen/gen_options.lua
new file mode 100644
index 0000000000..1947297a0e
--- /dev/null
+++ b/src/gen/gen_options.lua
@@ -0,0 +1,535 @@
+--- @module 'nvim.options'
+local options = require('nvim.options')
+local options_meta = options.options
+local cstr = options.cstr
+local valid_scopes = options.valid_scopes
+
+--- @param o vim.option_meta
+--- @return string
+local function get_values_var(o)
+  return ('opt_%s_values'):format(o.abbreviation or o.full_name)
+end
+
+--- @param s string
+--- @return string
+local function lowercase_to_titlecase(s)
+  return table.concat(vim.tbl_map(function(word) --- @param word string
+    return word:sub(1, 1):upper() .. word:sub(2)
+  end, vim.split(s, '[-_]')))
+end
+
+--- @param scope string
+--- @param option_name string
+--- @return string
+local function get_scope_option(scope, option_name)
+  return ('k%sOpt%s'):format(lowercase_to_titlecase(scope), lowercase_to_titlecase(option_name))
+end
+
+local redraw_flags = {
+  ui_option = 'kOptFlagUIOption',
+  tabline = 'kOptFlagRedrTabl',
+  statuslines = 'kOptFlagRedrStat',
+  current_window = 'kOptFlagRedrWin',
+  current_buffer = 'kOptFlagRedrBuf',
+  all_windows = 'kOptFlagRedrAll',
+  curswant = 'kOptFlagCurswant',
+  highlight_only = 'kOptFlagHLOnly',
+}
+
+local list_flags = {
+  comma = 'kOptFlagComma',
+  onecomma = 'kOptFlagOneComma',
+  commacolon = 'kOptFlagComma|kOptFlagColon',
+  onecommacolon = 'kOptFlagOneComma|kOptFlagColon',
+  flags = 'kOptFlagFlagList',
+  flagscomma = 'kOptFlagComma|kOptFlagFlagList',
+}
+
+--- @param o vim.option_meta
+--- @return string
+local function get_flags(o)
+  --- @type string[]
+  local flags = { '0' }
+
+  --- @param f string
+  local function add_flag(f)
+    table.insert(flags, f)
+  end
+
+  if o.list then
+    add_flag(list_flags[o.list])
+  end
+
+  for _, r_flag in ipairs(o.redraw or {}) do
+    add_flag(redraw_flags[r_flag])
+  end
+
+  if o.expand then
+    add_flag('kOptFlagExpand')
+    if o.expand == 'nodefault' then
+      add_flag('kOptFlagNoDefExp')
+    end
+  end
+
+  for _, flag_desc in ipairs({
+    { 'nodefault', 'NoDefault' },
+    { 'no_mkrc', 'NoMkrc' },
+    { 'secure' },
+    { 'gettext' },
+    { 'noglob', 'NoGlob' },
+    { 'normal_fname_chars', 'NFname' },
+    { 'normal_dname_chars', 'NDname' },
+    { 'pri_mkrc', 'PriMkrc' },
+    { 'deny_in_modelines', 'NoML' },
+    { 'deny_duplicates', 'NoDup' },
+    { 'modelineexpr', 'MLE' },
+    { 'func' },
+  }) do
+    local key_name, flag_suffix = flag_desc[1], flag_desc[2]
+    if o[key_name] then
+      local def_name = 'kOptFlag' .. (flag_suffix or lowercase_to_titlecase(key_name))
+      add_flag(def_name)
+    end
+  end
+
+  return table.concat(flags, '|')
+end
+
+--- @param opt_type vim.option_type
+--- @return string
+local function opt_type_enum(opt_type)
+  return ('kOptValType%s'):format(lowercase_to_titlecase(opt_type))
+end
+
+--- @param scope vim.option_scope
+--- @return string
+local function opt_scope_enum(scope)
+  return ('kOptScope%s'):format(lowercase_to_titlecase(scope))
+end
+
+--- @param o vim.option_meta
+--- @return string
+local function get_scope_flags(o)
+  local scope_flags = '0'
+
+  for _, scope in ipairs(o.scope) do
+    scope_flags = ('%s | (1 << %s)'):format(scope_flags, opt_scope_enum(scope))
+  end
+
+  return scope_flags
+end
+
+--- @param o vim.option_meta
+--- @return string
+local function get_scope_idx(o)
+  --- @type string[]
+  local strs = {}
+
+  for _, scope in pairs(valid_scopes) do
+    local has_scope = vim.tbl_contains(o.scope, scope)
+    strs[#strs + 1] = ('      [%s] = %s'):format(
+      opt_scope_enum(scope),
+      get_scope_option(scope, has_scope and o.full_name or 'Invalid')
+    )
+  end
+
+  return ('{\n%s\n    }'):format(table.concat(strs, ',\n'))
+end
+
+--- @param s string
+--- @return string
+local function static_cstr_as_string(s)
+  return ('{ .data = %s, .size = sizeof(%s) - 1 }'):format(s, s)
+end
+
+--- @param v vim.option_value|function
+--- @return string
+local function get_opt_val(v)
+  --- @type vim.option_type
+  local v_type
+
+  if type(v) == 'function' then
+    v, v_type = v() --[[ @as string, vim.option_type ]]
+
+    if v_type == 'string' then
+      v = static_cstr_as_string(v)
+    end
+  else
+    v_type = type(v) --[[ @as vim.option_type ]]
+
+    if v_type == 'boolean' then
+      v = v and 'true' or 'false'
+    elseif v_type == 'number' then
+      v = ('%iL'):format(v)
+    elseif v_type == 'string' then
+      --- @cast v string
+      v = static_cstr_as_string(cstr(v))
+    end
+  end
+
+  return ('{ .type = %s, .data.%s = %s }'):format(opt_type_enum(v_type), v_type, v)
+end
+
+--- @param d vim.option_value|function
+--- @param n string
+--- @return string
+local function get_defaults(d, n)
+  if d == nil then
+    error("option '" .. n .. "' should have a default value")
+  end
+  return get_opt_val(d)
+end
+
+--- @param i integer
+--- @param o vim.option_meta
+--- @param write fun(...: string)
+local function dump_option(i, o, write)
+  write('  [', ('%u'):format(i - 1) .. ']={')
+  write('    .fullname=', cstr(o.full_name))
+  if o.abbreviation then
+    write('    .shortname=', cstr(o.abbreviation))
+  end
+  write('    .type=', opt_type_enum(o.type))
+  write('    .flags=', get_flags(o))
+  write('    .scope_flags=', get_scope_flags(o))
+  write('    .scope_idx=', get_scope_idx(o))
+  write('    .values=', (o.values and get_values_var(o) or 'NULL'))
+  write('    .values_len=', (o.values and #o.values or '0'))
+  write('    .flags_var=', (o.flags_varname and ('&%s'):format(o.flags_varname) or 'NULL'))
+  if o.enable_if then
+    write(('#if defined(%s)'):format(o.enable_if))
+  end
+
+  local is_window_local = #o.scope == 1 and o.scope[1] == 'win'
+
+  if is_window_local then
+    write('    .var=NULL')
+  elseif o.varname then
+    write('    .var=&', o.varname)
+  elseif o.immutable then
+    -- Immutable options can directly point to the default value.
+    write(('    .var=&options[%u].def_val.data'):format(i - 1))
+  else
+    error('Option must be immutable or have a variable.')
+  end
+
+  write('    .immutable=', (o.immutable and 'true' or 'false'))
+  write('    .opt_did_set_cb=', o.cb or 'NULL')
+  write('    .opt_expand_cb=', o.expand_cb or 'NULL')
+
+  if o.enable_if then
+    write('#else')
+    -- Hidden option directly points to default value.
+    write(('    .var=&options[%u].def_val.data'):format(i - 1))
+    -- Option is always immutable on the false branch of `enable_if`.
+    write('    .immutable=true')
+    write('#endif')
+  end
+
+  if not o.defaults then
+    write('    .def_val=NIL_OPTVAL')
+  elseif o.defaults.condition then
+    write(('#if defined(%s)'):format(o.defaults.condition))
+    write('    .def_val=', get_defaults(o.defaults.if_true, o.full_name))
+    if o.defaults.if_false then
+      write('#else')
+      write('    .def_val=', get_defaults(o.defaults.if_false, o.full_name))
+    end
+    write('#endif')
+  else
+    write('    .def_val=', get_defaults(o.defaults.if_true, o.full_name))
+  end
+
+  write('  },')
+end
+
+--- @param prefix string
+--- @param values vim.option_valid_values
+local function preorder_traversal(prefix, values)
+  local out = {} --- @type string[]
+
+  local function add(s)
+    table.insert(out, s)
+  end
+
+  add('')
+  add(('EXTERN const char *(%s_values[%s]) INIT( = {'):format(prefix, #vim.tbl_keys(values) + 1))
+
+  --- @type [string,vim.option_valid_values][]
+  local children = {}
+
+  for _, value in ipairs(values) do
+    if type(value) == 'string' then
+      add(('  "%s",'):format(value))
+    else
+      assert(type(value) == 'table' and type(value[1]) == 'string' and type(value[2]) == 'table')
+      add(('  "%s",'):format(value[1]))
+      table.insert(children, value)
+    end
+  end
+
+  add('  NULL')
+  add('});')
+
+  for _, value in pairs(children) do
+    -- Remove trailing colon from the added prefix to prevent syntax errors.
+    add(preorder_traversal(prefix .. '_' .. value[1]:gsub(':$', ''), value[2]))
+  end
+
+  return table.concat(out, '\n')
+end
+
+--- @param o vim.option_meta
+--- @return string
+local function gen_opt_enum(o)
+  local out = {} --- @type string[]
+
+  local function add(s)
+    table.insert(out, s)
+  end
+
+  add('')
+  add('typedef enum {')
+
+  local opt_name = lowercase_to_titlecase(o.abbreviation or o.full_name)
+  --- @type table<string,integer>
+  local enum_values
+
+  if type(o.flags) == 'table' then
+    enum_values = o.flags --[[ @as table<string,integer> ]]
+  else
+    enum_values = {}
+    for i, flag_name in ipairs(o.values) do
+      assert(type(flag_name) == 'string')
+      enum_values[flag_name] = math.pow(2, i - 1)
+    end
+  end
+
+  -- Sort the keys by the flag value so that the enum can be generated in order.
+  --- @type string[]
+  local flag_names = vim.tbl_keys(enum_values)
+  table.sort(flag_names, function(a, b)
+    return enum_values[a] < enum_values[b]
+  end)
+
+  for _, flag_name in pairs(flag_names) do
+    add(
+      ('  kOpt%sFlag%s = 0x%02x,'):format(
+        opt_name,
+        lowercase_to_titlecase(flag_name:gsub(':$', '')),
+        enum_values[flag_name]
+      )
+    )
+  end
+
+  add(('} Opt%sFlags;'):format(opt_name))
+
+  return table.concat(out, '\n')
+end
+
+--- @param output_file string
+--- @return table<string,string> options_index Map of option name to option index
+local function gen_enums(output_file)
+  --- Options for each scope.
+  --- @type table<string, vim.option_meta[]>
+  local scope_options = {}
+  for _, scope in ipairs(valid_scopes) do
+    scope_options[scope] = {}
+  end
+
+  local fd = assert(io.open(output_file, 'w'))
+
+  --- @param s string
+  local function write(s)
+    fd:write(s)
+    fd:write('\n')
+  end
+
+  -- Generate options enum file
+  write('// IWYU pragma: private, include "nvim/option_defs.h"')
+  write('')
+
+  --- Map of option name to option index
+  --- @type table<string, string>
+  local option_index = {}
+
+  -- Generate option index enum and populate the `option_index` and `scope_option` dicts.
+  write('typedef enum {')
+  write('  kOptInvalid = -1,')
+
+  for i, o in ipairs(options_meta) do
+    local enum_val_name = 'kOpt' .. lowercase_to_titlecase(o.full_name)
+    write(('  %s = %u,'):format(enum_val_name, i - 1))
+
+    option_index[o.full_name] = enum_val_name
+
+    if o.abbreviation then
+      option_index[o.abbreviation] = enum_val_name
+    end
+
+    local alias = o.alias or {} --[[@as string[] ]]
+    for _, v in ipairs(alias) do
+      option_index[v] = enum_val_name
+    end
+
+    for _, scope in ipairs(o.scope) do
+      table.insert(scope_options[scope], o)
+    end
+  end
+
+  write('  // Option count')
+  write('#define kOptCount ' .. tostring(#options_meta))
+  write('} OptIndex;')
+
+  -- Generate option index enum for each scope
+  for _, scope in ipairs(valid_scopes) do
+    write('')
+
+    local scope_name = lowercase_to_titlecase(scope)
+    write('typedef enum {')
+    write(('  %s = -1,'):format(get_scope_option(scope, 'Invalid')))
+
+    for idx, option in ipairs(scope_options[scope]) do
+      write(('  %s = %u,'):format(get_scope_option(scope, option.full_name), idx - 1))
+    end
+
+    write(('  // %s option count'):format(scope_name))
+    write(('#define %s %d'):format(get_scope_option(scope, 'Count'), #scope_options[scope]))
+    write(('} %sOptIndex;'):format(scope_name))
+  end
+
+  -- Generate reverse lookup from option scope index to option index for each scope.
+  for _, scope in ipairs(valid_scopes) do
+    write('')
+    write(('EXTERN const OptIndex %s_opt_idx[] INIT( = {'):format(scope))
+    for _, option in ipairs(scope_options[scope]) do
+      local idx = option_index[option.full_name]
+      write(('  [%s] = %s,'):format(get_scope_option(scope, option.full_name), idx))
+    end
+    write('});')
+  end
+
+  fd:close()
+
+  return option_index
+end
+
+--- @param output_file string
+--- @param option_index table<string,string>
+local function gen_map(output_file, option_index)
+  -- Generate option index map.
+  local hashy = require('gen.hashy')
+
+  local neworder, hashfun = hashy.hashy_hash(
+    'find_option',
+    vim.tbl_keys(option_index),
+    function(idx)
+      return ('option_hash_elems[%s].name'):format(idx)
+    end
+  )
+
+  local fd = assert(io.open(output_file, 'w'))
+
+  --- @param s string
+  local function write(s)
+    fd:write(s)
+    fd:write('\n')
+  end
+
+  write('static const struct { const char *name; OptIndex opt_idx; } option_hash_elems[] = {')
+
+  for _, name in ipairs(neworder) do
+    assert(option_index[name] ~= nil)
+    write(('  { .name = "%s", .opt_idx = %s },'):format(name, option_index[name]))
+  end
+
+  write('};')
+  write('')
+  write('static ' .. hashfun)
+
+  fd:close()
+end
+
+--- @param output_file string
+local function gen_vars(output_file)
+  local fd = assert(io.open(output_file, 'w'))
+
+  --- @param s string
+  local function write(s)
+    fd:write(s)
+    fd:write('\n')
+  end
+
+  write('// IWYU pragma: private, include "nvim/option_vars.h"')
+
+  -- Generate enums for option flags.
+  for _, o in ipairs(options_meta) do
+    if o.flags and (type(o.flags) == 'table' or o.values) then
+      write(gen_opt_enum(o))
+    end
+  end
+
+  -- Generate valid values for each option.
+  for _, option in ipairs(options_meta) do
+    -- Since option values can be nested, we need to do preorder traversal to generate the values.
+    if option.values then
+      local values_var = ('opt_%s'):format(option.abbreviation or option.full_name)
+      write(preorder_traversal(values_var, option.values))
+    end
+  end
+
+  fd:close()
+end
+
+--- @param output_file string
+local function gen_options(output_file)
+  local fd = assert(io.open(output_file, 'w'))
+
+  --- @param ... string
+  local function write(...)
+    local s = table.concat({ ... }, '')
+    fd:write(s)
+    if s:match('^    %.') then
+      fd:write(',')
+    end
+    fd:write('\n')
+  end
+
+  -- Generate options[] array.
+  write([[
+  #include "nvim/ex_docmd.h"
+  #include "nvim/ex_getln.h"
+  #include "nvim/insexpand.h"
+  #include "nvim/mapping.h"
+  #include "nvim/ops.h"
+  #include "nvim/option.h"
+  #include "nvim/optionstr.h"
+  #include "nvim/quickfix.h"
+  #include "nvim/runtime.h"
+  #include "nvim/tag.h"
+  #include "nvim/window.h"
+
+  static vimoption_T options[] = {]])
+
+  for i, o in ipairs(options_meta) do
+    dump_option(i, o, write)
+  end
+
+  write('};')
+
+  fd:close()
+end
+
+local function main()
+  local options_file = arg[1]
+  local options_enum_file = arg[2]
+  local options_map_file = arg[3]
+  local option_vars_file = arg[4]
+
+  local option_index = gen_enums(options_enum_file)
+  gen_map(options_map_file, option_index)
+  gen_vars(option_vars_file)
+  gen_options(options_file)
+end
+
+main()
diff --git a/src/gen/gen_vimdoc.lua b/src/gen/gen_vimdoc.lua
new file mode 100755
index 0000000000..2fe7224ea5
--- /dev/null
+++ b/src/gen/gen_vimdoc.lua
@@ -0,0 +1,1041 @@
+#!/usr/bin/env -S nvim -l
+--- Generates Nvim :help docs from Lua/C docstrings
+---
+--- The generated :help text for each function is formatted as follows:
+--- - Max width of 78 columns (`TEXT_WIDTH`).
+--- - Indent with spaces (not tabs).
+--- - Indent of 4 columns for body text (`INDENTATION`).
+--- - Function signature and helptag (right-aligned) on the same line.
+---   - Signature and helptag must have a minimum of 8 spaces between them.
+---   - If the signature is too long, it is placed on the line after the helptag.
+---     Signature wraps with subsequent lines indented to the open parenthesis.
+---   - Subsection bodies are indented an additional 4 spaces.
+--- - Body consists of function description, parameters, return description, and
+---   C declaration (`INCLUDE_C_DECL`).
+--- - Parameters are omitted for the `void` and `Error *` types, or if the
+---   parameter is marked as [out].
+--- - Each function documentation is separated by a single line.
+
+local luacats_parser = require('gen.luacats_parser')
+local cdoc_parser = require('gen.cdoc_parser')
+local util = require('gen.util')
+
+local fmt = string.format
+
+local wrap = util.wrap
+local md_to_vimdoc = util.md_to_vimdoc
+
+local TEXT_WIDTH = 78
+local INDENTATION = 4
+
+--- @class (exact) nvim.gen_vimdoc.Config
+---
+--- Generated documentation target, e.g. api.txt
+--- @field filename string
+---
+--- @field section_order string[]
+---
+--- List of files/directories for doxygen to read, relative to `base_dir`.
+--- @field files string[]
+---
+--- @field exclude_types? true
+---
+--- Section name overrides. Key: filename (e.g., vim.c)
+--- @field section_name? table<string,string>
+---
+--- @field fn_name_pat? string
+---
+--- @field fn_xform? fun(fun: nvim.luacats.parser.fun)
+---
+--- For generated section names.
+--- @field section_fmt fun(name: string): string
+---
+--- @field helptag_fmt fun(name: string): string|string[]
+---
+--- Per-function helptag.
+--- @field fn_helptag_fmt? fun(fun: nvim.luacats.parser.fun): string
+---
+--- @field append_only? string[]
+
+local function contains(t, xs)
+  return vim.tbl_contains(xs, t)
+end
+
+--- @type {level:integer, prerelease:boolean}?
+local nvim_api_info_
+
+--- @return {level: integer, prerelease:boolean}
+local function nvim_api_info()
+  if not nvim_api_info_ then
+    --- @type integer?, boolean?
+    local level, prerelease
+    for l in io.lines('CMakeLists.txt') do
+      --- @cast l string
+      if level and prerelease then
+        break
+      end
+      local m1 = l:match('^set%(NVIM_API_LEVEL%s+(%d+)%)')
+      if m1 then
+        level = tonumber(m1) --[[@as integer]]
+      end
+      local m2 = l:match('^set%(NVIM_API_PRERELEASE%s+(%w+)%)')
+      if m2 then
+        prerelease = m2 == 'true'
+      end
+    end
+    nvim_api_info_ = { level = level, prerelease = prerelease }
+  end
+
+  return nvim_api_info_
+end
+
+--- @param fun nvim.luacats.parser.fun
+--- @return string
+local function fn_helptag_fmt_common(fun)
+  local fn_sfx = fun.table and '' or '()'
+  if fun.classvar then
+    return fmt('%s:%s%s', fun.classvar, fun.name, fn_sfx)
+  end
+  if fun.module then
+    return fmt('%s.%s%s', fun.module, fun.name, fn_sfx)
+  end
+  return fun.name .. fn_sfx
+end
+
+--- @type table<string,nvim.gen_vimdoc.Config>
+local config = {
+  api = {
+    filename = 'api.txt',
+    section_order = {
+      'vim.c',
+      'vimscript.c',
+      'command.c',
+      'options.c',
+      'buffer.c',
+      'extmark.c',
+      'window.c',
+      'win_config.c',
+      'tabpage.c',
+      'autocmd.c',
+      'ui.c',
+    },
+    exclude_types = true,
+    fn_name_pat = 'nvim_.*',
+    files = { 'src/nvim/api' },
+    section_name = {
+      ['vim.c'] = 'Global',
+    },
+    section_fmt = function(name)
+      return name .. ' Functions'
+    end,
+    helptag_fmt = function(name)
+      return fmt('api-%s', name:lower())
+    end,
+  },
+  lua = {
+    filename = 'lua.txt',
+    section_order = {
+      'hl.lua',
+      'diff.lua',
+      'mpack.lua',
+      'json.lua',
+      'base64.lua',
+      'spell.lua',
+      'builtin.lua',
+      '_options.lua',
+      '_editor.lua',
+      '_inspector.lua',
+      'shared.lua',
+      'loader.lua',
+      'uri.lua',
+      'ui.lua',
+      'filetype.lua',
+      'keymap.lua',
+      'fs.lua',
+      'glob.lua',
+      'lpeg.lua',
+      're.lua',
+      'regex.lua',
+      'secure.lua',
+      'version.lua',
+      'iter.lua',
+      'snippet.lua',
+      'text.lua',
+      'tohtml.lua',
+    },
+    files = {
+      'runtime/lua/vim/iter.lua',
+      'runtime/lua/vim/_editor.lua',
+      'runtime/lua/vim/_options.lua',
+      'runtime/lua/vim/shared.lua',
+      'runtime/lua/vim/loader.lua',
+      'runtime/lua/vim/uri.lua',
+      'runtime/lua/vim/ui.lua',
+      'runtime/lua/vim/filetype.lua',
+      'runtime/lua/vim/keymap.lua',
+      'runtime/lua/vim/fs.lua',
+      'runtime/lua/vim/hl.lua',
+      'runtime/lua/vim/secure.lua',
+      'runtime/lua/vim/version.lua',
+      'runtime/lua/vim/_inspector.lua',
+      'runtime/lua/vim/snippet.lua',
+      'runtime/lua/vim/text.lua',
+      'runtime/lua/vim/glob.lua',
+      'runtime/lua/vim/_meta/builtin.lua',
+      'runtime/lua/vim/_meta/diff.lua',
+      'runtime/lua/vim/_meta/mpack.lua',
+      'runtime/lua/vim/_meta/json.lua',
+      'runtime/lua/vim/_meta/base64.lua',
+      'runtime/lua/vim/_meta/regex.lua',
+      'runtime/lua/vim/_meta/lpeg.lua',
+      'runtime/lua/vim/_meta/re.lua',
+      'runtime/lua/vim/_meta/spell.lua',
+      'runtime/lua/tohtml.lua',
+    },
+    fn_xform = function(fun)
+      if contains(fun.module, { 'vim.uri', 'vim.shared', 'vim._editor' }) then
+        fun.module = 'vim'
+      end
+
+      if fun.module == 'vim' and contains(fun.name, { 'cmd', 'inspect' }) then
+        fun.table = nil
+      end
+
+      if fun.classvar or vim.startswith(fun.name, 'vim.') or fun.module == 'vim.iter' then
+        return
+      end
+
+      fun.name = fmt('%s.%s', fun.module, fun.name)
+    end,
+    section_name = {
+      ['_inspector.lua'] = 'inspector',
+    },
+    section_fmt = function(name)
+      name = name:lower()
+      if name == '_editor' then
+        return 'Lua module: vim'
+      elseif name == '_options' then
+        return 'LUA-VIMSCRIPT BRIDGE'
+      elseif name == 'builtin' then
+        return 'VIM'
+      end
+      if
+        contains(name, {
+          'hl',
+          'mpack',
+          'json',
+          'base64',
+          'diff',
+          'spell',
+          'regex',
+          'lpeg',
+          're',
+        })
+      then
+        return 'VIM.' .. name:upper()
+      end
+      if name == 'tohtml' then
+        return 'Lua module: tohtml'
+      end
+      return 'Lua module: vim.' .. name
+    end,
+    helptag_fmt = function(name)
+      if name == '_editor' then
+        return 'lua-vim'
+      elseif name == '_options' then
+        return 'lua-vimscript'
+      elseif name == 'tohtml' then
+        return 'tohtml'
+      end
+      return 'vim.' .. name:lower()
+    end,
+    fn_helptag_fmt = function(fun)
+      local name = fun.name
+
+      if vim.startswith(name, 'vim.') then
+        local fn_sfx = fun.table and '' or '()'
+        return name .. fn_sfx
+      elseif fun.classvar == 'Option' then
+        return fmt('vim.opt:%s()', name)
+      end
+
+      return fn_helptag_fmt_common(fun)
+    end,
+    append_only = {
+      'shared.lua',
+    },
+  },
+  lsp = {
+    filename = 'lsp.txt',
+    section_order = {
+      'lsp.lua',
+      'client.lua',
+      'buf.lua',
+      'diagnostic.lua',
+      'codelens.lua',
+      'completion.lua',
+      'folding_range.lua',
+      'inlay_hint.lua',
+      'tagfunc.lua',
+      'semantic_tokens.lua',
+      'handlers.lua',
+      'util.lua',
+      'log.lua',
+      'rpc.lua',
+      'protocol.lua',
+    },
+    files = {
+      'runtime/lua/vim/lsp',
+      'runtime/lua/vim/lsp.lua',
+    },
+    fn_xform = function(fun)
+      fun.name = fun.name:gsub('result%.', '')
+      if fun.module == 'vim.lsp.protocol' then
+        fun.classvar = nil
+      end
+    end,
+    section_fmt = function(name)
+      if name:lower() == 'lsp' then
+        return 'Lua module: vim.lsp'
+      end
+      return 'Lua module: vim.lsp.' .. name:lower()
+    end,
+    helptag_fmt = function(name)
+      if name:lower() == 'lsp' then
+        return 'lsp-core'
+      end
+      return fmt('lsp-%s', name:lower())
+    end,
+  },
+  diagnostic = {
+    filename = 'diagnostic.txt',
+    section_order = {
+      'diagnostic.lua',
+    },
+    files = { 'runtime/lua/vim/diagnostic.lua' },
+    section_fmt = function()
+      return 'Lua module: vim.diagnostic'
+    end,
+    helptag_fmt = function()
+      return 'diagnostic-api'
+    end,
+  },
+  treesitter = {
+    filename = 'treesitter.txt',
+    section_order = {
+      'tstree.lua',
+      'tsnode.lua',
+      'treesitter.lua',
+      'language.lua',
+      'query.lua',
+      'highlighter.lua',
+      'languagetree.lua',
+      'dev.lua',
+    },
+    files = {
+      'runtime/lua/vim/treesitter/_meta/',
+      'runtime/lua/vim/treesitter.lua',
+      'runtime/lua/vim/treesitter/',
+    },
+    section_fmt = function(name)
+      if name:lower() == 'treesitter' then
+        return 'Lua module: vim.treesitter'
+      elseif name:lower() == 'tstree' then
+        return 'TREESITTER TREES'
+      elseif name:lower() == 'tsnode' then
+        return 'TREESITTER NODES'
+      end
+      return 'Lua module: vim.treesitter.' .. name:lower()
+    end,
+    helptag_fmt = function(name)
+      if name:lower() == 'treesitter' then
+        return 'lua-treesitter-core'
+      elseif name:lower() == 'query' then
+        return 'lua-treesitter-query'
+      elseif name:lower() == 'tstree' then
+        return { 'treesitter-tree', 'TSTree' }
+      elseif name:lower() == 'tsnode' then
+        return { 'treesitter-node', 'TSNode' }
+      end
+      return 'treesitter-' .. name:lower()
+    end,
+  },
+  editorconfig = {
+    filename = 'editorconfig.txt',
+    files = {
+      'runtime/lua/editorconfig.lua',
+    },
+    section_order = {
+      'editorconfig.lua',
+    },
+    section_fmt = function(_name)
+      return 'EditorConfig integration'
+    end,
+    helptag_fmt = function(name)
+      return name:lower()
+    end,
+    fn_xform = function(fun)
+      fun.table = true
+      fun.name = vim.split(fun.name, '.', { plain = true })[2]
+    end,
+  },
+  health = {
+    filename = 'health.txt',
+    files = {
+      'runtime/lua/vim/health.lua',
+    },
+    section_order = {
+      'health.lua',
+    },
+    section_fmt = function(_name)
+      return 'Checkhealth'
+    end,
+    helptag_fmt = function()
+      return { 'vim.health', 'health' }
+    end,
+  },
+}
+
+--- @param ty string
+--- @param generics table<string,string>
+--- @return string
+local function replace_generics(ty, generics)
+  if ty:sub(-2) == '[]' then
+    local ty0 = ty:sub(1, -3)
+    if generics[ty0] then
+      return generics[ty0] .. '[]'
+    end
+  elseif ty:sub(-1) == '?' then
+    local ty0 = ty:sub(1, -2)
+    if generics[ty0] then
+      return generics[ty0] .. '?'
+    end
+  end
+
+  return generics[ty] or ty
+end
+
+--- @param name string
+local function fmt_field_name(name)
+  local name0, opt = name:match('^([^?]*)(%??)$')
+  return fmt('{%s}%s', name0, opt)
+end
+
+--- @param ty string
+--- @param generics? table<string,string>
+--- @param default? string
+local function render_type(ty, generics, default)
+  if generics then
+    ty = replace_generics(ty, generics)
+  end
+  ty = ty:gsub('%s*|%s*nil', '?')
+  ty = ty:gsub('nil%s*|%s*(.*)', '%1?')
+  ty = ty:gsub('%s*|%s*', '|')
+  if default then
+    return fmt('(`%s`, default: %s)', ty, default)
+  end
+  return fmt('(`%s`)', ty)
+end
+
+--- @param p nvim.luacats.parser.param|nvim.luacats.parser.field
+local function should_render_field_or_param(p)
+  return not p.nodoc
+    and not p.access
+    and not contains(p.name, { '_', 'self' })
+    and not vim.startswith(p.name, '_')
+end
+
+--- @param desc? string
+--- @return string?, string?
+local function get_default(desc)
+  if not desc then
+    return
+  end
+
+  local default = desc:match('\n%s*%([dD]efault: ([^)]+)%)')
+  if default then
+    desc = desc:gsub('\n%s*%([dD]efault: [^)]+%)', '')
+  end
+
+  return desc, default
+end
+
+--- @param ty string
+--- @param classes? table<string,nvim.luacats.parser.class>
+--- @return nvim.luacats.parser.class?
+local function get_class(ty, classes)
+  if not classes then
+    return
+  end
+
+  local cty = ty:gsub('%s*|%s*nil', '?'):gsub('?$', ''):gsub('%[%]$', '')
+
+  return classes[cty]
+end
+
+--- @param obj nvim.luacats.parser.param|nvim.luacats.parser.return|nvim.luacats.parser.field
+--- @param classes? table<string,nvim.luacats.parser.class>
+local function inline_type(obj, classes)
+  local ty = obj.type
+  if not ty then
+    return
+  end
+
+  local cls = get_class(ty, classes)
+
+  if not cls or cls.nodoc then
+    return
+  end
+
+  if not cls.inlinedoc then
+    -- Not inlining so just add a: "See |tag|."
+    local tag = fmt('|%s|', cls.name)
+    if obj.desc and obj.desc:find(tag) then
+      -- Tag already there
+      return
+    end
+
+    -- TODO(lewis6991): Aim to remove this. Need this to prevent dead
+    -- references to types defined in runtime/lua/vim/lsp/_meta/protocol.lua
+    if not vim.startswith(cls.name, 'vim.') then
+      return
+    end
+
+    obj.desc = obj.desc or ''
+    local period = (obj.desc == '' or vim.endswith(obj.desc, '.')) and '' or '.'
+    obj.desc = obj.desc .. fmt('%s See %s.', period, tag)
+    return
+  end
+
+  local ty_isopt = (ty:match('%?$') or ty:match('%s*|%s*nil')) ~= nil
+  local ty_islist = (ty:match('%[%]$')) ~= nil
+  ty = ty_isopt and 'table?' or ty_islist and 'table[]' or 'table'
+
+  local desc = obj.desc or ''
+  if cls.desc then
+    desc = desc .. cls.desc
+  elseif desc == '' then
+    if ty_islist then
+      desc = desc .. 'A list of objects with the following fields:'
+    elseif cls.parent then
+      desc = desc .. fmt('Extends |%s| with the additional fields:', cls.parent)
+    else
+      desc = desc .. 'A table with the following fields:'
+    end
+  end
+
+  local desc_append = {}
+  for _, f in ipairs(cls.fields) do
+    if not f.access then
+      local fdesc, default = get_default(f.desc)
+      local fty = render_type(f.type, nil, default)
+      local fnm = fmt_field_name(f.name)
+      table.insert(desc_append, table.concat({ '-', fnm, fty, fdesc }, ' '))
+    end
+  end
+
+  desc = desc .. '\n' .. table.concat(desc_append, '\n')
+  obj.type = ty
+  obj.desc = desc
+end
+
+--- @param xs (nvim.luacats.parser.param|nvim.luacats.parser.field)[]
+--- @param generics? table<string,string>
+--- @param classes? table<string,nvim.luacats.parser.class>
+--- @param exclude_types? true
+--- @param cfg nvim.gen_vimdoc.Config
+local function render_fields_or_params(xs, generics, classes, exclude_types, cfg)
+  local ret = {} --- @type string[]
+
+  xs = vim.tbl_filter(should_render_field_or_param, xs)
+
+  local indent = 0
+  for _, p in ipairs(xs) do
+    if p.type or p.desc then
+      indent = math.max(indent, #p.name + 3)
+    end
+    if exclude_types then
+      p.type = nil
+    end
+  end
+
+  for _, p in ipairs(xs) do
+    local pdesc, default = get_default(p.desc)
+    p.desc = pdesc
+
+    inline_type(p, classes)
+    local nm, ty = p.name, p.type
+
+    local desc = p.classvar and string.format('See |%s|.', cfg.fn_helptag_fmt(p)) or p.desc
+
+    local fnm = p.kind == 'operator' and fmt('op(%s)', nm) or fmt_field_name(nm)
+    local pnm = fmt('      • %-' .. indent .. 's', fnm)
+
+    if ty then
+      local pty = render_type(ty, generics, default)
+
+      if desc then
+        table.insert(ret, pnm)
+        if #pty > TEXT_WIDTH - indent then
+          vim.list_extend(ret, { ' ', pty, '\n' })
+          table.insert(ret, md_to_vimdoc(desc, 9 + indent, 9 + indent, TEXT_WIDTH, true))
+        else
+          desc = fmt('%s %s', pty, desc)
+          table.insert(ret, md_to_vimdoc(desc, 1, 9 + indent, TEXT_WIDTH, true))
+        end
+      else
+        table.insert(ret, fmt('%s %s\n', pnm, pty))
+      end
+    else
+      if desc then
+        table.insert(ret, pnm)
+        table.insert(ret, md_to_vimdoc(desc, 1, 9 + indent, TEXT_WIDTH, true))
+      end
+    end
+  end
+
+  return table.concat(ret)
+end
+
+--- @param class nvim.luacats.parser.class
+--- @param classes table<string,nvim.luacats.parser.class>
+--- @param cfg nvim.gen_vimdoc.Config
+local function render_class(class, classes, cfg)
+  if class.access or class.nodoc or class.inlinedoc then
+    return
+  end
+
+  local ret = {} --- @type string[]
+
+  table.insert(ret, fmt('*%s*\n', class.name))
+
+  if class.parent then
+    local txt = fmt('Extends: |%s|', class.parent)
+    table.insert(ret, md_to_vimdoc(txt, INDENTATION, INDENTATION, TEXT_WIDTH))
+    table.insert(ret, '\n')
+  end
+
+  if class.desc then
+    table.insert(ret, md_to_vimdoc(class.desc, INDENTATION, INDENTATION, TEXT_WIDTH))
+  end
+
+  local fields_txt = render_fields_or_params(class.fields, nil, classes, nil, cfg)
+  if not fields_txt:match('^%s*$') then
+    table.insert(ret, '\n    Fields: ~\n')
+    table.insert(ret, fields_txt)
+  end
+  table.insert(ret, '\n')
+
+  return table.concat(ret)
+end
+
+--- @param classes table<string,nvim.luacats.parser.class>
+--- @param cfg nvim.gen_vimdoc.Config
+local function render_classes(classes, cfg)
+  local ret = {} --- @type string[]
+
+  for _, class in vim.spairs(classes) do
+    ret[#ret + 1] = render_class(class, classes, cfg)
+  end
+
+  return table.concat(ret)
+end
+
+--- @param fun nvim.luacats.parser.fun
+--- @param cfg nvim.gen_vimdoc.Config
+local function render_fun_header(fun, cfg)
+  local ret = {} --- @type string[]
+
+  local args = {} --- @type string[]
+  for _, p in ipairs(fun.params or {}) do
+    if p.name ~= 'self' then
+      args[#args + 1] = fmt_field_name(p.name)
+    end
+  end
+
+  local nm = fun.name
+  if fun.classvar then
+    nm = fmt('%s:%s', fun.classvar, nm)
+  end
+  if nm == 'vim.bo' then
+    nm = 'vim.bo[{bufnr}]'
+  end
+  if nm == 'vim.wo' then
+    nm = 'vim.wo[{winid}][{bufnr}]'
+  end
+
+  local proto = fun.table and nm or nm .. '(' .. table.concat(args, ', ') .. ')'
+
+  local tag = '*' .. cfg.fn_helptag_fmt(fun) .. '*'
+
+  if #proto + #tag > TEXT_WIDTH - 8 then
+    table.insert(ret, fmt('%78s\n', tag))
+    local name, pargs = proto:match('([^(]+%()(.*)')
+    table.insert(ret, name)
+    table.insert(ret, wrap(pargs, 0, #name, TEXT_WIDTH))
+  else
+    local pad = TEXT_WIDTH - #proto - #tag
+    table.insert(ret, proto .. string.rep(' ', pad) .. tag)
+  end
+
+  return table.concat(ret)
+end
+
+--- @param returns nvim.luacats.parser.return[]
+--- @param generics? table<string,string>
+--- @param classes? table<string,nvim.luacats.parser.class>
+--- @param exclude_types boolean
+local function render_returns(returns, generics, classes, exclude_types)
+  local ret = {} --- @type string[]
+
+  returns = vim.deepcopy(returns)
+  if exclude_types then
+    for _, r in ipairs(returns) do
+      r.type = nil
+    end
+  end
+
+  if #returns > 1 then
+    table.insert(ret, '    Return (multiple): ~\n')
+  elseif #returns == 1 and next(returns[1]) then
+    table.insert(ret, '    Return: ~\n')
+  end
+
+  for _, p in ipairs(returns) do
+    inline_type(p, classes)
+    local rnm, ty, desc = p.name, p.type, p.desc
+
+    local blk = {} --- @type string[]
+    if ty then
+      blk[#blk + 1] = render_type(ty, generics)
+    end
+    blk[#blk + 1] = rnm
+    blk[#blk + 1] = desc
+
+    table.insert(ret, md_to_vimdoc(table.concat(blk, ' '), 8, 8, TEXT_WIDTH, true))
+  end
+
+  return table.concat(ret)
+end
+
+--- @param fun nvim.luacats.parser.fun
+--- @param classes table<string,nvim.luacats.parser.class>
+--- @param cfg nvim.gen_vimdoc.Config
+local function render_fun(fun, classes, cfg)
+  if fun.access or fun.deprecated or fun.nodoc then
+    return
+  end
+
+  if cfg.fn_name_pat and not fun.name:match(cfg.fn_name_pat) then
+    return
+  end
+
+  if vim.startswith(fun.name, '_') or fun.name:find('[:.]_') then
+    return
+  end
+
+  local ret = {} --- @type string[]
+
+  table.insert(ret, render_fun_header(fun, cfg))
+  table.insert(ret, '\n')
+
+  if fun.since then
+    local since = assert(tonumber(fun.since), 'invalid @since on ' .. fun.name)
+    local info = nvim_api_info()
+    if since == 0 or (info.prerelease and since == info.level) then
+      -- Experimental = (since==0 or current prerelease)
+      local s = 'WARNING: This feature is experimental/unstable.'
+      table.insert(ret, md_to_vimdoc(s, INDENTATION, INDENTATION, TEXT_WIDTH))
+      table.insert(ret, '\n')
+    else
+      local v = assert(util.version_level[since], 'invalid @since on ' .. fun.name)
+      fun.attrs = fun.attrs or {}
+      table.insert(fun.attrs, ('Since: %s'):format(v))
+    end
+  end
+
+  if fun.desc then
+    table.insert(ret, md_to_vimdoc(fun.desc, INDENTATION, INDENTATION, TEXT_WIDTH))
+  end
+
+  if fun.notes then
+    table.insert(ret, '\n    Note: ~\n')
+    for _, p in ipairs(fun.notes) do
+      table.insert(ret, '      • ' .. md_to_vimdoc(p.desc, 0, 8, TEXT_WIDTH, true))
+    end
+  end
+
+  if fun.attrs then
+    table.insert(ret, '\n    Attributes: ~\n')
+    for _, attr in ipairs(fun.attrs) do
+      local attr_str = ({
+        textlock = 'not allowed when |textlock| is active or in the |cmdwin|',
+        textlock_allow_cmdwin = 'not allowed when |textlock| is active',
+        fast = '|api-fast|',
+        remote_only = '|RPC| only',
+        lua_only = 'Lua |vim.api| only',
+      })[attr] or attr
+      table.insert(ret, fmt('        %s\n', attr_str))
+    end
+  end
+
+  if fun.params and #fun.params > 0 then
+    local param_txt =
+      render_fields_or_params(fun.params, fun.generics, classes, cfg.exclude_types, cfg)
+    if not param_txt:match('^%s*$') then
+      table.insert(ret, '\n    Parameters: ~\n')
+      ret[#ret + 1] = param_txt
+    end
+  end
+
+  if fun.returns then
+    local txt = render_returns(fun.returns, fun.generics, classes, cfg.exclude_types)
+    if not txt:match('^%s*$') then
+      table.insert(ret, '\n')
+      ret[#ret + 1] = txt
+    end
+  end
+
+  if fun.see then
+    table.insert(ret, '\n    See also: ~\n')
+    for _, p in ipairs(fun.see) do
+      table.insert(ret, '      • ' .. md_to_vimdoc(p.desc, 0, 8, TEXT_WIDTH, true))
+    end
+  end
+
+  table.insert(ret, '\n')
+  return table.concat(ret)
+end
+
+--- @param funs nvim.luacats.parser.fun[]
+--- @param classes table<string,nvim.luacats.parser.class>
+--- @param cfg nvim.gen_vimdoc.Config
+local function render_funs(funs, classes, cfg)
+  local ret = {} --- @type string[]
+
+  for _, f in ipairs(funs) do
+    if cfg.fn_xform then
+      cfg.fn_xform(f)
+    end
+    ret[#ret + 1] = render_fun(f, classes, cfg)
+  end
+
+  -- Sort via prototype. Experimental API functions ("nvim__") sort last.
+  table.sort(ret, function(a, b)
+    local a1 = ('\n' .. a):match('\n[a-zA-Z_][^\n]+\n')
+    local b1 = ('\n' .. b):match('\n[a-zA-Z_][^\n]+\n')
+
+    local a1__ = a1:find('^%s*nvim__') and 1 or 0
+    local b1__ = b1:find('^%s*nvim__') and 1 or 0
+    if a1__ ~= b1__ then
+      return a1__ < b1__
+    end
+
+    return a1:lower() < b1:lower()
+  end)
+
+  return table.concat(ret)
+end
+
+--- @return string
+local function get_script_path()
+  local str = debug.getinfo(2, 'S').source:sub(2)
+  return str:match('(.*[/\\])') or './'
+end
+
+local script_path = get_script_path()
+local base_dir = vim.fs.dirname(vim.fs.dirname(vim.fs.dirname(script_path)))
+
+local function delete_lines_below(doc_file, tokenstr)
+  local lines = {} --- @type string[]
+  local found = false
+  for line in io.lines(doc_file) do
+    if line:find(vim.pesc(tokenstr)) then
+      found = true
+      break
+    end
+    lines[#lines + 1] = line
+  end
+  if not found then
+    error(fmt('not found: %s in %s', tokenstr, doc_file))
+  end
+  lines[#lines] = nil
+  local fp = assert(io.open(doc_file, 'w'))
+  fp:write(table.concat(lines, '\n'))
+  fp:write('\n')
+  fp:close()
+end
+
+--- @param x string
+local function mktitle(x)
+  if x == 'ui' then
+    return 'UI'
+  end
+  return x:sub(1, 1):upper() .. x:sub(2)
+end
+
+--- @class nvim.gen_vimdoc.Section
+--- @field name string
+--- @field title string
+--- @field help_tag string
+--- @field funs_txt string
+--- @field doc? string[]
+
+--- @param filename string
+--- @param cfg nvim.gen_vimdoc.Config
+--- @param section_docs table<string,nvim.gen_vimdoc.Section>
+--- @param funs_txt string
+--- @return nvim.gen_vimdoc.Section?
+local function make_section(filename, cfg, section_docs, funs_txt)
+  -- filename: e.g., 'autocmd.c'
+  -- name: e.g. 'autocmd'
+  local name = filename:match('(.*)%.[a-z]+')
+
+  -- Formatted (this is what's going to be written in the vimdoc)
+  -- e.g., "Autocmd Functions"
+  local sectname = cfg.section_name and cfg.section_name[filename] or mktitle(name)
+
+  -- section tag: e.g., "*api-autocmd*"
+  local help_labels = cfg.helptag_fmt(sectname)
+  if type(help_labels) == 'table' then
+    help_labels = table.concat(help_labels, '* *')
+  end
+  local help_tags = '*' .. help_labels .. '*'
+
+  if funs_txt == '' and #section_docs == 0 then
+    return
+  end
+
+  return {
+    name = sectname,
+    title = cfg.section_fmt(sectname),
+    help_tag = help_tags,
+    funs_txt = funs_txt,
+    doc = section_docs,
+  }
+end
+
+--- @param section nvim.gen_vimdoc.Section
+--- @param add_header? boolean
+local function render_section(section, add_header)
+  local doc = {} --- @type string[]
+
+  if add_header ~= false then
+    vim.list_extend(doc, {
+      string.rep('=', TEXT_WIDTH),
+      '\n',
+      section.title,
+      fmt('%' .. (TEXT_WIDTH - section.title:len()) .. 's', section.help_tag),
+    })
+  end
+
+  local sdoc = '\n\n' .. table.concat(section.doc or {}, '\n')
+  if sdoc:find('[^%s]') then
+    doc[#doc + 1] = sdoc
+  end
+
+  if section.funs_txt then
+    table.insert(doc, '\n\n')
+    table.insert(doc, section.funs_txt)
+  end
+
+  return table.concat(doc)
+end
+
+local parsers = {
+  lua = luacats_parser.parse,
+  c = cdoc_parser.parse,
+  h = cdoc_parser.parse,
+}
+
+--- @param files string[]
+local function expand_files(files)
+  for k, f in pairs(files) do
+    if vim.fn.isdirectory(f) == 1 then
+      table.remove(files, k)
+      for path, ty in vim.fs.dir(f) do
+        if ty == 'file' then
+          table.insert(files, vim.fs.joinpath(f, path))
+        end
+      end
+    end
+  end
+end
+
+--- @param cfg nvim.gen_vimdoc.Config
+local function gen_target(cfg)
+  cfg.fn_helptag_fmt = cfg.fn_helptag_fmt or fn_helptag_fmt_common
+  print('Target:', cfg.filename)
+  local sections = {} --- @type table<string,nvim.gen_vimdoc.Section>
+
+  expand_files(cfg.files)
+
+  --- @type table<string,[table<string,nvim.luacats.parser.class>, nvim.luacats.parser.fun[], string[]]>
+  local file_results = {}
+
+  --- @type table<string,nvim.luacats.parser.class>
+  local all_classes = {}
+
+  --- First pass so we can collect all classes
+  for _, f in vim.spairs(cfg.files) do
+    local ext = assert(f:match('%.([^.]+)$')) --[[@as 'h'|'c'|'lua']]
+    local parser = assert(parsers[ext])
+    local classes, funs, briefs = parser(f)
+    file_results[f] = { classes, funs, briefs }
+    all_classes = vim.tbl_extend('error', all_classes, classes)
+  end
+
+  for f, r in vim.spairs(file_results) do
+    local classes, funs, briefs = r[1], r[2], r[3]
+
+    local briefs_txt = {} --- @type string[]
+    for _, b in ipairs(briefs) do
+      briefs_txt[#briefs_txt + 1] = md_to_vimdoc(b, 0, 0, TEXT_WIDTH)
+    end
+    print('    Processing file:', f)
+    local funs_txt = render_funs(funs, all_classes, cfg)
+    if next(classes) then
+      local classes_txt = render_classes(classes, cfg)
+      if vim.trim(classes_txt) ~= '' then
+        funs_txt = classes_txt .. '\n' .. funs_txt
+      end
+    end
+    -- FIXME: Using f_base will confuse `_meta/protocol.lua` with `protocol.lua`
+    local f_base = vim.fs.basename(f)
+    sections[f_base] = make_section(f_base, cfg, briefs_txt, funs_txt)
+  end
+
+  local first_section_tag = sections[cfg.section_order[1]].help_tag
+  local docs = {} --- @type string[]
+  for _, f in ipairs(cfg.section_order) do
+    local section = sections[f]
+    if section then
+      print(string.format("    Rendering section: '%s'", section.title))
+      local add_sep_and_header = not vim.tbl_contains(cfg.append_only or {}, f)
+      docs[#docs + 1] = render_section(section, add_sep_and_header)
+    end
+  end
+
+  table.insert(
+    docs,
+    fmt(' vim:tw=78:ts=8:sw=%d:sts=%d:et:ft=help:norl:\n', INDENTATION, INDENTATION)
+  )
+
+  local doc_file = vim.fs.joinpath(base_dir, 'runtime', 'doc', cfg.filename)
+
+  if vim.uv.fs_stat(doc_file) then
+    delete_lines_below(doc_file, first_section_tag)
+  end
+
+  local fp = assert(io.open(doc_file, 'a'))
+  fp:write(table.concat(docs, '\n'))
+  fp:close()
+end
+
+local function run()
+  for _, cfg in vim.spairs(config) do
+    gen_target(cfg)
+  end
+end
+
+run()
diff --git a/src/gen/gen_vimvim.lua b/src/gen/gen_vimvim.lua
new file mode 100644
index 0000000000..d2b1f48a4c
--- /dev/null
+++ b/src/gen/gen_vimvim.lua
@@ -0,0 +1,156 @@
+local mpack = vim.mpack
+
+local syntax_file = arg[1]
+local funcs_file = arg[2]
+
+local lld = {}
+local syn_fd = io.open(syntax_file, 'w')
+lld.line_length = 0
+local function w(s)
+  syn_fd:write(s)
+  if s:find('\n') then
+    lld.line_length = #(s:gsub('.*\n', ''))
+  else
+    lld.line_length = lld.line_length + #s
+  end
+end
+
+local options = require('nvim.options')
+local auevents = require('nvim.auevents')
+local ex_cmds = require('nvim.ex_cmds')
+
+local function cmd_kw(prev_cmd, cmd)
+  if not prev_cmd then
+    return cmd:sub(1, 1) .. '[' .. cmd:sub(2) .. ']'
+  else
+    local shift = 1
+    while cmd:sub(shift, shift) == prev_cmd:sub(shift, shift) do
+      shift = shift + 1
+    end
+    if cmd:sub(1, shift) == 'def' then
+      shift = shift + 1
+    end
+    if shift >= #cmd then
+      return cmd
+    else
+      return cmd:sub(1, shift) .. '[' .. cmd:sub(shift + 1) .. ']'
+    end
+  end
+end
+
+-- Exclude these from the vimCommand keyword list, they are handled specially
+-- in syntax/vim.vim (vimAugroupKey, vimAutoCmd, vimGlobal, vimSubst). #9327
+local function is_special_cased_cmd(cmd)
+  return (
+    cmd == 'augroup'
+    or cmd == 'autocmd'
+    or cmd == 'doautocmd'
+    or cmd == 'doautoall'
+    or cmd == 'global'
+    or cmd == 'substitute'
+  )
+end
+
+local vimcmd_start = 'syn keyword vimCommand contained '
+local vimcmd_end = ' nextgroup=vimBang'
+w(vimcmd_start)
+
+local prev_cmd = nil
+for _, cmd_desc in ipairs(ex_cmds.cmds) do
+  if lld.line_length > 850 then
+    w(vimcmd_end .. '\n' .. vimcmd_start)
+  end
+  local cmd = cmd_desc.command
+  if cmd:match('%w') and cmd ~= 'z' and not is_special_cased_cmd(cmd) then
+    w(' ' .. cmd_kw(prev_cmd, cmd))
+  end
+  if cmd == 'delete' then
+    -- Add special abbreviations of :delete
+    w(' ' .. cmd_kw('d', 'dl'))
+    w(' ' .. cmd_kw('del', 'dell'))
+    w(' ' .. cmd_kw('dele', 'delel'))
+    w(' ' .. cmd_kw('delet', 'deletl'))
+    w(' ' .. cmd_kw('delete', 'deletel'))
+    w(' ' .. cmd_kw('d', 'dp'))
+    w(' ' .. cmd_kw('de', 'dep'))
+    w(' ' .. cmd_kw('del', 'delp'))
+    w(' ' .. cmd_kw('dele', 'delep'))
+    w(' ' .. cmd_kw('delet', 'deletp'))
+    w(' ' .. cmd_kw('delete', 'deletep'))
+  end
+  prev_cmd = cmd
+end
+
+w(vimcmd_end .. '\n')
+
+local vimopt_start = 'syn keyword vimOption contained '
+local vimopt_end = ' skipwhite nextgroup=vimSetEqual,vimSetMod'
+w('\n' .. vimopt_start)
+
+for _, opt_desc in ipairs(options.options) do
+  if not opt_desc.immutable then
+    if lld.line_length > 850 then
+      w(vimopt_end .. '\n' .. vimopt_start)
+    end
+    w(' ' .. opt_desc.full_name)
+    if opt_desc.abbreviation then
+      w(' ' .. opt_desc.abbreviation)
+    end
+    if opt_desc.type == 'boolean' then
+      w(' inv' .. opt_desc.full_name)
+      w(' no' .. opt_desc.full_name)
+      if opt_desc.abbreviation then
+        w(' inv' .. opt_desc.abbreviation)
+        w(' no' .. opt_desc.abbreviation)
+      end
+    end
+  end
+end
+
+w(vimopt_end .. '\n')
+
+w('\nsyn case ignore')
+local vimau_start = 'syn keyword vimAutoEvent contained '
+w('\n\n' .. vimau_start)
+
+for _, au in ipairs(auevents.events) do
+  if not auevents.nvim_specific[au[1]] then
+    if lld.line_length > 850 then
+      w('\n' .. vimau_start)
+    end
+    w(' ' .. au[1])
+    for _, alias in ipairs(au[2]) do
+      if lld.line_length > 850 then
+        w('\n' .. vimau_start)
+      end
+      -- au[1] is aliased to alias
+      w(' ' .. alias)
+    end
+  end
+end
+
+local nvimau_start = 'syn keyword nvimAutoEvent contained '
+w('\n\n' .. nvimau_start)
+
+for au, _ in vim.spairs(auevents.nvim_specific) do
+  if lld.line_length > 850 then
+    w('\n' .. nvimau_start)
+  end
+  w(' ' .. au)
+end
+
+w('\n\nsyn case match')
+local vimfun_start = 'syn keyword vimFuncName contained '
+w('\n\n' .. vimfun_start)
+local funcs = mpack.decode(io.open(funcs_file, 'rb'):read('*all'))
+for _, name in ipairs(funcs) do
+  if name then
+    if lld.line_length > 850 then
+      w('\n' .. vimfun_start)
+    end
+    w(' ' .. name)
+  end
+end
+
+w('\n')
+syn_fd:close()
diff --git a/src/gen/hashy.lua b/src/gen/hashy.lua
new file mode 100644
index 0000000000..74b7655324
--- /dev/null
+++ b/src/gen/hashy.lua
@@ -0,0 +1,145 @@
+-- HASHY McHASHFACE
+
+local M = {}
+_G.d = M
+
+local function setdefault(table, key)
+  local val = table[key]
+  if val == nil then
+    val = {}
+    table[key] = val
+  end
+  return val
+end
+
+function M.build_pos_hash(strings)
+  local len_buckets = {}
+  local maxlen = 0
+  for _, s in ipairs(strings) do
+    table.insert(setdefault(len_buckets, #s), s)
+    if #s > maxlen then
+      maxlen = #s
+    end
+  end
+
+  local len_pos_buckets = {}
+  local worst_buck_size = 0
+
+  for len = 1, maxlen do
+    local strs = len_buckets[len]
+    if strs then
+      -- the best position so far generates `best_bucket`
+      -- with `minsize` worst case collisions
+      local bestpos, minsize, best_bucket = nil, #strs * 2, nil
+      for pos = 1, len do
+        local try_bucket = {}
+        for _, str in ipairs(strs) do
+          local poschar = string.sub(str, pos, pos)
+          table.insert(setdefault(try_bucket, poschar), str)
+        end
+        local maxsize = 1
+        for _, pos_strs in pairs(try_bucket) do
+          maxsize = math.max(maxsize, #pos_strs)
+        end
+        if maxsize < minsize then
+          bestpos = pos
+          minsize = maxsize
+          best_bucket = try_bucket
+        end
+      end
+      len_pos_buckets[len] = { bestpos, best_bucket }
+      worst_buck_size = math.max(worst_buck_size, minsize)
+    end
+  end
+  return len_pos_buckets, maxlen, worst_buck_size
+end
+
+function M.switcher(put, tab, maxlen, worst_buck_size)
+  local neworder = {} --- @type string[]
+  put '  switch (len) {\n'
+  local bucky = worst_buck_size > 1
+  for len = 1, maxlen do
+    local vals = tab[len]
+    if vals then
+      put('    case ' .. len .. ': ')
+      local pos, posbuck = unpack(vals)
+      local keys = vim.tbl_keys(posbuck)
+      if #keys > 1 then
+        table.sort(keys)
+        put('switch (str[' .. (pos - 1) .. ']) {\n')
+        for _, c in ipairs(keys) do
+          local buck = posbuck[c]
+          local startidx = #neworder
+          vim.list_extend(neworder, buck)
+          local endidx = #neworder
+          put("      case '" .. c .. "': ")
+          if len == 1 then
+            put('return ' .. startidx .. ';\n')
+          else
+            put('low = ' .. startidx .. '; ')
+            if bucky then
+              put('high = ' .. endidx .. '; ')
+            end
+            put 'break;\n'
+          end
+        end
+        put '      default: break;\n'
+        put '    }\n    '
+      else
+        local startidx = #neworder
+        table.insert(neworder, posbuck[keys[1]][1])
+        local endidx = #neworder
+        put('low = ' .. startidx .. '; ')
+        if bucky then
+          put('high = ' .. endidx .. '; ')
+        end
+      end
+      put 'break;\n'
+    end
+  end
+  put '    default: break;\n'
+  put '  }\n'
+  return neworder
+end
+
+function M.hashy_hash(name, strings, access)
+  local stats = {}
+  local put = function(str)
+    table.insert(stats, str)
+  end
+  local len_pos_buckets, maxlen, worst_buck_size = M.build_pos_hash(strings)
+  put('int ' .. name .. '_hash(const char *str, size_t len)\n{\n')
+  if maxlen == 1 then
+    put('\n') -- nothing
+  elseif worst_buck_size > 1 then
+    put('  int low = 0, high = 0;\n')
+  else
+    put('  int low = -1;\n')
+  end
+  local neworder = M.switcher(put, len_pos_buckets, maxlen, worst_buck_size)
+  if maxlen == 1 then
+    put([[
+  return -1;
+]])
+  elseif worst_buck_size > 1 then
+    put([[
+  for (int i = low; i < high; i++) {
+    if (!memcmp(str, ]] .. access('i') .. [[, len)) {
+      return i;
+    }
+  }
+  return -1;
+]])
+  else
+    put([[
+  if (low < 0 || memcmp(str, ]] .. access('low') .. [[, len)) {
+    return -1;
+  }
+  return low;
+]])
+  end
+  put '}\n\n'
+  return neworder, table.concat(stats)
+end
+
+return M
diff --git a/src/gen/luacats_grammar.lua b/src/gen/luacats_grammar.lua
new file mode 100644
index 0000000000..b700bcf58f
--- /dev/null
+++ b/src/gen/luacats_grammar.lua
@@ -0,0 +1,207 @@
+--[[!
+LPEG grammar for LuaCATS
+]]
+
+local lpeg = vim.lpeg
+local P, R, S = lpeg.P, lpeg.R, lpeg.S
+local C, Ct, Cg = lpeg.C, lpeg.Ct, lpeg.Cg
+
+--- @param x vim.lpeg.Pattern
+local function rep(x)
+  return x ^ 0
+end
+
+--- @param x vim.lpeg.Pattern
+local function rep1(x)
+  return x ^ 1
+end
+
+--- @param x vim.lpeg.Pattern
+local function opt(x)
+  return x ^ -1
+end
+
+local ws = rep1(S(' \t'))
+local fill = opt(ws)
+local any = P(1) -- (consume one character)
+local letter = R('az', 'AZ')
+local num = R('09')
+
+--- @param x string | vim.lpeg.Pattern
+local function Pf(x)
+  return fill * P(x) * fill
+end
+
+--- @param x string | vim.lpeg.Pattern
+local function Plf(x)
+  return fill * P(x)
+end
+
+--- @param x string
+local function Sf(x)
+  return fill * S(x) * fill
+end
+
+--- @param x vim.lpeg.Pattern
+local function paren(x)
+  return Pf('(') * x * fill * P(')')
+end
+
+--- @param x vim.lpeg.Pattern
+local function parenOpt(x)
+  return paren(x) + x
+end
+
+--- @param x vim.lpeg.Pattern
+local function comma1(x)
+  return parenOpt(x * rep(Pf(',') * x))
+end
+
+--- @param x vim.lpeg.Pattern
+local function comma(x)
+  return opt(comma1(x))
+end
+
+--- @type table<string,vim.lpeg.Pattern>
+local v = setmetatable({}, {
+  __index = function(_, k)
+    return lpeg.V(k)
+  end,
+})
+
+--- @class nvim.luacats.Param
+--- @field kind 'param'
+--- @field name string
+--- @field type string
+--- @field desc? string
+
+--- @class nvim.luacats.Return
+--- @field kind 'return'
+--- @field [integer] { type: string, name?: string}
+--- @field desc? string
+
+--- @class nvim.luacats.Generic
+--- @field kind 'generic'
+--- @field name string
+--- @field type? string
+
+--- @class nvim.luacats.Class
+--- @field kind 'class'
+--- @field name string
+--- @field parent? string
+--- @field access? 'private'|'protected'|'package'
+
+--- @class nvim.luacats.Field
+--- @field kind 'field'
+--- @field name string
+--- @field type string
+--- @field desc? string
+--- @field access? 'private'|'protected'|'package'
+
+--- @class nvim.luacats.Note
+--- @field desc? string
+
+--- @alias nvim.luacats.grammar.result
+--- | nvim.luacats.Param
+--- | nvim.luacats.Return
+--- | nvim.luacats.Generic
+--- | nvim.luacats.Class
+--- | nvim.luacats.Field
+--- | nvim.luacats.Note
+
+--- @class nvim.luacats.grammar
+--- @field match fun(self, input: string): nvim.luacats.grammar.result?
+
+local function annot(nm, pat)
+  if type(nm) == 'string' then
+    nm = P(nm)
+  end
+  if pat then
+    return Ct(Cg(P(nm), 'kind') * fill * pat)
+  end
+  return Ct(Cg(P(nm), 'kind'))
+end
+
+local colon = Pf(':')
+local ellipsis = P('...')
+local ident_first = P('_') + letter
+local ident = ident_first * rep(ident_first + num)
+local opt_ident = ident * opt(P('?'))
+local ty_ident_sep = S('-._')
+local ty_ident = ident * rep(ty_ident_sep * ident)
+local string_single = P "'" * rep(any - P "'") * P "'"
+local string_double = P('"') * rep(any - P('"')) * P('"')
+local generic = P('`') * ty_ident * P('`')
+local literal = string_single + string_double + (opt(P('-')) * rep1(num)) + P('false') + P('true')
+local ty_prims = ty_ident + literal + generic
+
+local array_postfix = rep1(Plf('[]'))
+local opt_postfix = rep1(Plf('?'))
+local rep_array_opt_postfix = rep(array_postfix + opt_postfix)
+
+local typedef = P({
+  'typedef',
+  typedef = C(v.type),
+
+  type = v.ty * rep_array_opt_postfix * rep(Pf('|') * v.ty * rep_array_opt_postfix),
+  ty = v.composite + paren(v.typedef),
+  composite = (v.types * array_postfix) + (v.types * opt_postfix) + v.types,
+  types = v.generics + v.kv_table + v.tuple + v.dict + v.table_literal + v.fun + ty_prims,
+
+  tuple = Pf('[') * comma1(v.type) * Plf(']'),
+  dict = Pf('{') * comma1(Pf('[') * v.type * Pf(']') * colon * v.type) * Plf('}'),
+  kv_table = Pf('table') * Pf('<') * v.type * Pf(',') * v.type * Plf('>'),
+  table_literal = Pf('{') * comma1(opt_ident * Pf(':') * v.type) * Plf('}'),
+  fun_param = (opt_ident + ellipsis) * opt(colon * v.type),
+  fun_ret = v.type + (ellipsis * opt(colon * v.type)),
+  fun = Pf('fun') * paren(comma(v.fun_param)) * opt(Pf(':') * comma1(v.fun_ret)),
+  generics = P(ty_ident) * Pf('<') * comma1(v.type) * Plf('>'),
+}) / function(match)
+  return vim.trim(match):gsub('^%((.*)%)$', '%1'):gsub('%?+', '?')
+end
+
+local access = P('private') + P('protected') + P('package')
+local caccess = Cg(access, 'access')
+local cattr = Cg(comma(access + P('exact')), 'access')
+local desc_delim = Sf '#:' + ws
+local desc = Cg(rep(any), 'desc')
+local opt_desc = opt(desc_delim * desc)
+local ty_name = Cg(ty_ident, 'name')
+local opt_parent = opt(colon * Cg(ty_ident, 'parent'))
+local lname = (ident + ellipsis) * opt(P('?'))
+
+local grammar = P {
+  rep1(P('@') * (v.ats + v.ext_ats)),
+
+  ats = annot('param', Cg(lname, 'name') * ws * v.ctype * opt_desc)
+    + annot('return', comma1(Ct(v.ctype * opt(ws * (ty_name + Cg(ellipsis, 'name'))))) * opt_desc)
+    + annot('type', comma1(Ct(v.ctype)) * opt_desc)
+    + annot('cast', ty_name * ws * opt(Sf('+-')) * v.ctype)
+    + annot('generic', ty_name * opt(colon * v.ctype))
+    + annot('class', opt(paren(cattr)) * fill * ty_name * opt_parent)
+    + annot('field', opt(caccess * ws) * v.field_name * ws * v.ctype * opt_desc)
+    + annot('operator', ty_name * opt(paren(Cg(v.ctype, 'argtype'))) * colon * v.ctype)
+    + annot(access)
+    + annot('deprecated')
+    + annot('alias', ty_name * opt(ws * v.ctype))
+    + annot('enum', ty_name)
+    + annot('overload', v.ctype)
+    + annot('see', opt(desc_delim) * desc)
+    + annot('diagnostic', opt(desc_delim) * desc)
+    + annot('meta'),
+
+  --- Custom extensions
+  ext_ats = (
+    annot('note', desc)
+    + annot('since', desc)
+    + annot('nodoc')
+    + annot('inlinedoc')
+    + annot('brief', desc)
+  ),
+
+  field_name = Cg(lname + (v.ty_index * opt(P('?'))), 'name'),
+  ty_index = C(Pf('[') * typedef * fill * P(']')),
+  ctype = Cg(typedef, 'type'),
+}
+
+return grammar --[[@as nvim.luacats.grammar]]
diff --git a/src/gen/luacats_parser.lua b/src/gen/luacats_parser.lua
new file mode 100644
index 0000000000..36bdc44076
--- /dev/null
+++ b/src/gen/luacats_parser.lua
@@ -0,0 +1,535 @@
+local luacats_grammar = require('gen.luacats_grammar')
+
+--- @class nvim.luacats.parser.param : nvim.luacats.Param
+
+--- @class nvim.luacats.parser.return
+--- @field name string
+--- @field type string
+--- @field desc string
+
+--- @class nvim.luacats.parser.note
+--- @field desc string
+
+--- @class nvim.luacats.parser.brief
+--- @field kind 'brief'
+--- @field desc string
+
+--- @class nvim.luacats.parser.alias
+--- @field kind 'alias'
+--- @field type string[]
+--- @field desc string
+
+--- @class nvim.luacats.parser.fun
+--- @field name string
+--- @field params nvim.luacats.parser.param[]
+--- @field returns nvim.luacats.parser.return[]
+--- @field desc string
+--- @field access? 'private'|'package'|'protected'
+--- @field class? string
+--- @field module? string
+--- @field modvar? string
+--- @field classvar? string
+--- @field deprecated? true
+--- @field since? string
+--- @field attrs? string[]
+--- @field nodoc? true
+--- @field generics? table<string,string>
+--- @field table? true
+--- @field notes? nvim.luacats.parser.note[]
+--- @field see? nvim.luacats.parser.note[]
+
+--- @class nvim.luacats.parser.field : nvim.luacats.Field
+--- @field classvar? string
+--- @field nodoc? true
+
+--- @class nvim.luacats.parser.class : nvim.luacats.Class
+--- @field desc? string
+--- @field nodoc? true
+--- @field inlinedoc? true
+--- @field fields nvim.luacats.parser.field[]
+--- @field notes? string[]
+
+--- @class nvim.luacats.parser.State
+--- @field doc_lines? string[]
+--- @field cur_obj? nvim.luacats.parser.obj
+--- @field last_doc_item? nvim.luacats.parser.param|nvim.luacats.parser.return|nvim.luacats.parser.note
+--- @field last_doc_item_indent? integer
+
+--- @alias nvim.luacats.parser.obj
+--- | nvim.luacats.parser.class
+--- | nvim.luacats.parser.fun
+--- | nvim.luacats.parser.brief
+--- | nvim.luacats.parser.alias
+
+-- Remove this when we document classes properly
+--- Some doc lines have the form:
+---   param name some.complex.type (table) description
+--- if so then transform the line to remove the complex type:
+---   param name (table) description
+--- @param line string
+local function use_type_alt(line)
+  for _, type in ipairs({ 'table', 'function' }) do
+    line = line:gsub('@param%s+([a-zA-Z_?]+)%s+.*%((' .. type .. ')%)', '@param %1 %2')
+    line = line:gsub('@param%s+([a-zA-Z_?]+)%s+.*%((' .. type .. '|nil)%)', '@param %1 %2')
+    line = line:gsub('@param%s+([a-zA-Z_?]+)%s+.*%((' .. type .. '%?)%)', '@param %1 %2')
+
+    line = line:gsub('@return%s+.*%((' .. type .. ')%)', '@return %1')
+    line = line:gsub('@return%s+.*%((' .. type .. '|nil)%)', '@return %1')
+    line = line:gsub('@return%s+.*%((' .. type .. '%?)%)', '@return %1')
+  end
+  return line
+end
+
+--- If we collected any `---` lines. Add them to the existing (or new) object
+--- Used for function/class descriptions and multiline param descriptions.
+--- @param state nvim.luacats.parser.State
+local function add_doc_lines_to_obj(state)
+  if state.doc_lines then
+    state.cur_obj = state.cur_obj or {}
+    local cur_obj = assert(state.cur_obj)
+    local txt = table.concat(state.doc_lines, '\n')
+    if cur_obj.desc then
+      cur_obj.desc = cur_obj.desc .. '\n' .. txt
+    else
+      cur_obj.desc = txt
+    end
+    state.doc_lines = nil
+  end
+end
+
+--- @param line string
+--- @param state nvim.luacats.parser.State
+local function process_doc_line(line, state)
+  line = line:sub(4):gsub('^%s+@', '@')
+  line = use_type_alt(line)
+
+  local parsed = luacats_grammar:match(line)
+
+  if not parsed then
+    if line:match('^ ') then
+      line = line:sub(2)
+    end
+
+    if state.last_doc_item then
+      if not state.last_doc_item_indent then
+        state.last_doc_item_indent = #line:match('^%s*') + 1
+      end
+      state.last_doc_item.desc = (state.last_doc_item.desc or '')
+        .. '\n'
+        .. line:sub(state.last_doc_item_indent or 1)
+    else
+      state.doc_lines = state.doc_lines or {}
+      table.insert(state.doc_lines, line)
+    end
+    return
+  end
+
+  state.last_doc_item_indent = nil
+  state.last_doc_item = nil
+  state.cur_obj = state.cur_obj or {}
+  local cur_obj = assert(state.cur_obj)
+
+  local kind = parsed.kind
+
+  if kind == 'brief' then
+    state.cur_obj = {
+      kind = 'brief',
+      desc = parsed.desc,
+    }
+  elseif kind == 'class' then
+    --- @cast parsed nvim.luacats.Class
+    cur_obj.kind = 'class'
+    cur_obj.name = parsed.name
+    cur_obj.parent = parsed.parent
+    cur_obj.access = parsed.access
+    cur_obj.desc = state.doc_lines and table.concat(state.doc_lines, '\n') or nil
+    state.doc_lines = nil
+    cur_obj.fields = {}
+  elseif kind == 'field' then
+    --- @cast parsed nvim.luacats.Field
+    parsed.desc = parsed.desc or state.doc_lines and table.concat(state.doc_lines, '\n') or nil
+    if parsed.desc then
+      parsed.desc = vim.trim(parsed.desc)
+    end
+    table.insert(cur_obj.fields, parsed)
+    state.doc_lines = nil
+  elseif kind == 'operator' then
+    parsed.desc = parsed.desc or state.doc_lines and table.concat(state.doc_lines, '\n') or nil
+    if parsed.desc then
+      parsed.desc = vim.trim(parsed.desc)
+    end
+    table.insert(cur_obj.fields, parsed)
+    state.doc_lines = nil
+  elseif kind == 'param' then
+    state.last_doc_item_indent = nil
+    cur_obj.params = cur_obj.params or {}
+    if vim.endswith(parsed.name, '?') then
+      parsed.name = parsed.name:sub(1, -2)
+      parsed.type = parsed.type .. '?'
+    end
+    state.last_doc_item = {
+      name = parsed.name,
+      type = parsed.type,
+      desc = parsed.desc,
+    }
+    table.insert(cur_obj.params, state.last_doc_item)
+  elseif kind == 'return' then
+    cur_obj.returns = cur_obj.returns or {}
+    for _, t in ipairs(parsed) do
+      table.insert(cur_obj.returns, {
+        name = t.name,
+        type = t.type,
+        desc = parsed.desc,
+      })
+    end
+    state.last_doc_item_indent = nil
+    state.last_doc_item = cur_obj.returns[#cur_obj.returns]
+  elseif kind == 'private' then
+    cur_obj.access = 'private'
+  elseif kind == 'package' then
+    cur_obj.access = 'package'
+  elseif kind == 'protected' then
+    cur_obj.access = 'protected'
+  elseif kind == 'deprecated' then
+    cur_obj.deprecated = true
+  elseif kind == 'inlinedoc' then
+    cur_obj.inlinedoc = true
+  elseif kind == 'nodoc' then
+    cur_obj.nodoc = true
+  elseif kind == 'since' then
+    cur_obj.since = parsed.desc
+  elseif kind == 'see' then
+    cur_obj.see = cur_obj.see or {}
+    table.insert(cur_obj.see, { desc = parsed.desc })
+  elseif kind == 'note' then
+    state.last_doc_item_indent = nil
+    state.last_doc_item = {
+      desc = parsed.desc,
+    }
+    cur_obj.notes = cur_obj.notes or {}
+    table.insert(cur_obj.notes, state.last_doc_item)
+  elseif kind == 'type' then
+    cur_obj.desc = parsed.desc
+    parsed.desc = nil
+    parsed.kind = nil
+    cur_obj.type = parsed
+  elseif kind == 'alias' then
+    state.cur_obj = {
+      kind = 'alias',
+      desc = parsed.desc,
+    }
+  elseif kind == 'enum' then
+    -- TODO
+    state.doc_lines = nil
+  elseif
+    vim.tbl_contains({
+      'diagnostic',
+      'cast',
+      'overload',
+      'meta',
+    }, kind)
+  then
+    -- Ignore
+    return
+  elseif kind == 'generic' then
+    cur_obj.generics = cur_obj.generics or {}
+    cur_obj.generics[parsed.name] = parsed.type or 'any'
+  else
+    error('Unhandled' .. vim.inspect(parsed))
+  end
+end
+
+--- @param fun nvim.luacats.parser.fun
+--- @return nvim.luacats.parser.field
+local function fun2field(fun)
+  local parts = { 'fun(' }
+
+  local params = {} ---@type string[]
+  for _, p in ipairs(fun.params or {}) do
+    params[#params + 1] = string.format('%s: %s', p.name, p.type)
+  end
+  parts[#parts + 1] = table.concat(params, ', ')
+  parts[#parts + 1] = ')'
+  if fun.returns then
+    parts[#parts + 1] = ': '
+    local tys = {} --- @type string[]
+    for _, p in ipairs(fun.returns) do
+      tys[#tys + 1] = p.type
+    end
+    parts[#parts + 1] = table.concat(tys, ', ')
+  end
+
+  return {
+    name = fun.name,
+    type = table.concat(parts, ''),
+    access = fun.access,
+    desc = fun.desc,
+    nodoc = fun.nodoc,
+  }
+end
+
+--- Function to normalize known form for declaring functions and normalize into a more standard
+--- form.
+--- @param line string
+--- @return string
+local function filter_decl(line)
+  -- M.fun = vim._memoize(function(...)
+  --   ->
+  -- function M.fun(...)
+  line = line:gsub('^local (.+) = memoize%([^,]+, function%((.*)%)$', 'local function %1(%2)')
+  line = line:gsub('^(.+) = memoize%([^,]+, function%((.*)%)$', 'function %1(%2)')
+  return line
+end
+
+--- @param line string
+--- @param state nvim.luacats.parser.State
+--- @param classes table<string,nvim.luacats.parser.class>
+--- @param classvars table<string,string>
+--- @param has_indent boolean
+local function process_lua_line(line, state, classes, classvars, has_indent)
+  line = filter_decl(line)
+
+  if state.cur_obj and state.cur_obj.kind == 'class' then
+    local nm = line:match('^local%s+([a-zA-Z0-9_]+)%s*=')
+    if nm then
+      classvars[nm] = state.cur_obj.name
+    end
+    return
+  end
+
+  do
+    local parent_tbl, sep, fun_or_meth_nm =
+      line:match('^function%s+([a-zA-Z0-9_]+)([.:])([a-zA-Z0-9_]+)%s*%(')
+    if parent_tbl then
+      -- Have a decl. Ensure cur_obj
+      state.cur_obj = state.cur_obj or {}
+      local cur_obj = assert(state.cur_obj)
+
+      -- Match `Class:foo` methods for defined classes
+      local class = classvars[parent_tbl]
+      if class then
+        --- @cast cur_obj nvim.luacats.parser.fun
+        cur_obj.name = fun_or_meth_nm
+        cur_obj.class = class
+        cur_obj.classvar = parent_tbl
+        -- Add self param to methods
+        if sep == ':' then
+          cur_obj.params = cur_obj.params or {}
+          table.insert(cur_obj.params, 1, {
+            name = 'self',
+            type = class,
+          })
+        end
+
+        -- Add method as the field to the class
+        local cls = classes[class]
+        local field = fun2field(cur_obj)
+        field.classvar = cur_obj.classvar
+        table.insert(cls.fields, field)
+        return
+      end
+
+      -- Match `M.foo`
+      if cur_obj and parent_tbl == cur_obj.modvar then
+        cur_obj.name = fun_or_meth_nm
+        return
+      end
+    end
+  end
+
+  do
+    -- Handle: `function A.B.C.foo(...)`
+    local fn_nm = line:match('^function%s+([.a-zA-Z0-9_]+)%s*%(')
+    if fn_nm then
+      state.cur_obj = state.cur_obj or {}
+      state.cur_obj.name = fn_nm
+      return
+    end
+  end
+
+  do
+    -- Handle: `M.foo = {...}` where `M` is the modvar
+    local parent_tbl, tbl_nm = line:match('([a-zA-Z_]+)%.([a-zA-Z0-9_]+)%s*=')
+    if state.cur_obj and parent_tbl and parent_tbl == state.cur_obj.modvar then
+      state.cur_obj.name = tbl_nm
+      state.cur_obj.table = true
+      return
+    end
+  end
+
+  do
+    -- Handle: `foo = {...}`
+    local tbl_nm = line:match('^([a-zA-Z0-9_]+)%s*=')
+    if tbl_nm and not has_indent then
+      state.cur_obj = state.cur_obj or {}
+      state.cur_obj.name = tbl_nm
+      state.cur_obj.table = true
+      return
+    end
+  end
+
+  do
+    -- Handle: `vim.foo = {...}`
+    local tbl_nm = line:match('^(vim%.[a-zA-Z0-9_]+)%s*=')
+    if state.cur_obj and tbl_nm and not has_indent then
+      state.cur_obj.name = tbl_nm
+      state.cur_obj.table = true
+      return
+    end
+  end
+
+  if state.cur_obj then
+    if line:find('^%s*%-%- luacheck:') then
+      state.cur_obj = nil
+    elseif line:find('^%s*local%s+') then
+      state.cur_obj = nil
+    elseif line:find('^%s*return%s+') then
+      state.cur_obj = nil
+    elseif line:find('^%s*[a-zA-Z_.]+%(%s+') then
+      state.cur_obj = nil
+    end
+  end
+end
+
+--- Determine the table name used to export functions of a module
+--- Usually this is `M`.
+--- @param str string
+--- @return string?
+local function determine_modvar(str)
+  local modvar --- @type string?
+  for line in vim.gsplit(str, '\n') do
+    do
+      --- @type string?
+      local m = line:match('^return%s+([a-zA-Z_]+)')
+      if m then
+        modvar = m
+      end
+    end
+    do
+      --- @type string?
+      local m = line:match('^return%s+setmetatable%(([a-zA-Z_]+),')
+      if m then
+        modvar = m
+      end
+    end
+  end
+  return modvar
+end
+
+--- @param obj nvim.luacats.parser.obj
+--- @param funs nvim.luacats.parser.fun[]
+--- @param classes table<string,nvim.luacats.parser.class>
+--- @param briefs string[]
+--- @param uncommitted nvim.luacats.parser.obj[]
+local function commit_obj(obj, classes, funs, briefs, uncommitted)
+  local commit = false
+  if obj.kind == 'class' then
+    --- @cast obj nvim.luacats.parser.class
+    if not classes[obj.name] then
+      classes[obj.name] = obj
+      commit = true
+    end
+  elseif obj.kind == 'alias' then
+    -- Just pretend
+    commit = true
+  elseif obj.kind == 'brief' then
+    --- @cast obj nvim.luacats.parser.brief`
+    briefs[#briefs + 1] = obj.desc
+    commit = true
+  else
+    --- @cast obj nvim.luacats.parser.fun`
+    if obj.name then
+      funs[#funs + 1] = obj
+      commit = true
+    end
+  end
+  if not commit then
+    table.insert(uncommitted, obj)
+  end
+  return commit
+end
+
+--- @param filename string
+--- @param uncommitted nvim.luacats.parser.obj[]
+-- luacheck: no unused
+local function dump_uncommitted(filename, uncommitted)
+  local out_path = 'luacats-uncommited/' .. filename:gsub('/', '%%') .. '.txt'
+  if #uncommitted > 0 then
+    print(string.format('Could not commit %d objects in %s', #uncommitted, filename))
+    vim.fn.mkdir(vim.fs.dirname(out_path), 'p')
+    local f = assert(io.open(out_path, 'w'))
+    for i, x in ipairs(uncommitted) do
+      f:write(i)
+      f:write(': ')
+      f:write(vim.inspect(x))
+      f:write('\n')
+    end
+    f:close()
+  else
+    vim.fn.delete(out_path)
+  end
+end
+
+local M = {}
+
+function M.parse_str(str, filename)
+  local funs = {} --- @type nvim.luacats.parser.fun[]
+  local classes = {} --- @type table<string,nvim.luacats.parser.class>
+  local briefs = {} --- @type string[]
+
+  local mod_return = determine_modvar(str)
+
+  --- @type string
+  local module = filename:match('.*/lua/([a-z_][a-z0-9_/]+)%.lua') or filename
+  module = module:gsub('/', '.')
+
+  local classvars = {} --- @type table<string,string>
+
+  local state = {} --- @type nvim.luacats.parser.State
+
+  -- Keep track of any partial objects we don't commit
+  local uncommitted = {} --- @type nvim.luacats.parser.obj[]
+
+  for line in vim.gsplit(str, '\n') do
+    local has_indent = line:match('^%s+') ~= nil
+    line = vim.trim(line)
+    if vim.startswith(line, '---') then
+      process_doc_line(line, state)
+    else
+      add_doc_lines_to_obj(state)
+
+      if state.cur_obj then
+        state.cur_obj.modvar = mod_return
+        state.cur_obj.module = module
+      end
+
+      process_lua_line(line, state, classes, classvars, has_indent)
+
+      -- Commit the object
+      local cur_obj = state.cur_obj
+      if cur_obj then
+        if not commit_obj(cur_obj, classes, funs, briefs, uncommitted) then
+          --- @diagnostic disable-next-line:inject-field
+          cur_obj.line = line
+        end
+      end
+
+      state = {}
+    end
+  end
+
+  -- dump_uncommitted(filename, uncommitted)
+
+  return classes, funs, briefs, uncommitted
+end
+
+--- @param filename string
+function M.parse(filename)
+  local f = assert(io.open(filename, 'r'))
+  local txt = f:read('*all')
+  f:close()
+
+  return M.parse_str(txt, filename)
+end
+
+return M
diff --git a/src/gen/nvim_version.lua.in b/src/gen/nvim_version.lua.in
new file mode 100644
index 0000000000..c29141fc68
--- /dev/null
+++ b/src/gen/nvim_version.lua.in
@@ -0,0 +1,9 @@
+return {
+  {"major", ${NVIM_VERSION_MAJOR}},
+  {"minor", ${NVIM_VERSION_MINOR}},
+  {"patch", ${NVIM_VERSION_PATCH}},
+  {"prerelease", "${NVIM_VERSION_PRERELEASE}" ~= ""},
+  {"api_level", ${NVIM_API_LEVEL}},
+  {"api_compatible", ${NVIM_API_LEVEL_COMPAT}},
+  {"api_prerelease", ${NVIM_API_PRERELEASE}},
+}
diff --git a/src/gen/preload.lua b/src/gen/preload.lua
new file mode 100644
index 0000000000..4856d8d7a1
--- /dev/null
+++ b/src/gen/preload.lua
@@ -0,0 +1,6 @@
+local srcdir = table.remove(arg, 1)
+
+package.path = (srcdir .. '/src/?.lua;') .. (srcdir .. '/runtime/lua/?.lua;') .. package.path
+
+arg[0] = table.remove(arg, 1)
+return loadfile(arg[0])()
diff --git a/src/gen/preload_nlua.lua b/src/gen/preload_nlua.lua
new file mode 100644
index 0000000000..a1d89105bc
--- /dev/null
+++ b/src/gen/preload_nlua.lua
@@ -0,0 +1,17 @@
+local srcdir = table.remove(arg, 1)
+local nlualib = table.remove(arg, 1)
+local gendir = table.remove(arg, 1)
+
+package.path = (srcdir .. '/src/?.lua;')
+  .. (srcdir .. '/runtime/lua/?.lua;')
+  .. (gendir .. '/?.lua;')
+  .. package.path
+
+_G.vim = require 'vim.shared'
+_G.vim.inspect = require 'vim.inspect'
+package.cpath = package.cpath .. ';' .. nlualib
+require 'nlua0'
+vim.NIL = vim.mpack.NIL -- WOW BOB WOW
+
+arg[0] = table.remove(arg, 1)
+return loadfile(arg[0])()
diff --git a/src/gen/util.lua b/src/gen/util.lua
new file mode 100644
index 0000000000..5940221abe
--- /dev/null
+++ b/src/gen/util.lua
@@ -0,0 +1,399 @@
+-- TODO(justinmk): move most of this to `vim.text`.
+
+local fmt = string.format
+
+--- @class nvim.util.MDNode
+--- @field [integer] nvim.util.MDNode
+--- @field type string
+--- @field text? string
+
+local INDENTATION = 4
+
+local NBSP = string.char(160)
+
+local M = {}
+
+local function contains(t, xs)
+  return vim.tbl_contains(xs, t)
+end
+
+-- Map of api_level:version, by inspection of:
+--    :lua= vim.mpack.decode(vim.fn.readfile('test/functional/fixtures/api_level_9.mpack','B')).version
+M.version_level = {
+  [13] = '0.11.0',
+  [12] = '0.10.0',
+  [11] = '0.9.0',
+  [10] = '0.8.0',
+  [9] = '0.7.0',
+  [8] = '0.6.0',
+  [7] = '0.5.0',
+  [6] = '0.4.0',
+  [5] = '0.3.2',
+  [4] = '0.3.0',
+  [3] = '0.2.1',
+  [2] = '0.2.0',
+  [1] = '0.1.0',
+}
+
+--- @param txt string
+--- @param srow integer
+--- @param scol integer
+--- @param erow? integer
+--- @param ecol? integer
+--- @return string
+local function slice_text(txt, srow, scol, erow, ecol)
+  local lines = vim.split(txt, '\n')
+
+  if srow == erow then
+    return lines[srow + 1]:sub(scol + 1, ecol)
+  end
+
+  if erow then
+    -- Trim the end
+    for _ = erow + 2, #lines do
+      table.remove(lines, #lines)
+    end
+  end
+
+  -- Trim the start
+  for _ = 1, srow do
+    table.remove(lines, 1)
+  end
+
+  lines[1] = lines[1]:sub(scol + 1)
+  lines[#lines] = lines[#lines]:sub(1, ecol)
+
+  return table.concat(lines, '\n')
+end
+
+--- @param text string
+--- @return nvim.util.MDNode
+local function parse_md_inline(text)
+  local parser = vim.treesitter.languagetree.new(text, 'markdown_inline')
+  local root = parser:parse(true)[1]:root()
+
+  --- @param node TSNode
+  --- @return nvim.util.MDNode?
+  local function extract(node)
+    local ntype = node:type()
+
+    if ntype:match('^%p$') then
+      return
+    end
+
+    --- @type table<any,any>
+    local ret = { type = ntype }
+    ret.text = vim.treesitter.get_node_text(node, text)
+
+    local row, col = 0, 0
+
+    for child, child_field in node:iter_children() do
+      local e = extract(child)
+      if e and ntype == 'inline' then
+        local srow, scol = child:start()
+        if (srow == row and scol > col) or srow > row then
+          local t = slice_text(ret.text, row, col, srow, scol)
+          if t and t ~= '' then
+            table.insert(ret, { type = 'text', j = true, text = t })
+          end
+        end
+        row, col = child:end_()
+      end
+
+      if child_field then
+        ret[child_field] = e
+      else
+        table.insert(ret, e)
+      end
+    end
+
+    if ntype == 'inline' and (row > 0 or col > 0) then
+      local t = slice_text(ret.text, row, col)
+      if t and t ~= '' then
+        table.insert(ret, { type = 'text', text = t })
+      end
+    end
+
+    return ret
+  end
+
+  return extract(root) or {}
+end
+
+--- @param text string
+--- @return nvim.util.MDNode
+local function parse_md(text)
+  local parser = vim.treesitter.languagetree.new(text, 'markdown', {
+    injections = { markdown = '' },
+  })
+
+  local root = parser:parse(true)[1]:root()
+
+  local EXCLUDE_TEXT_TYPE = {
+    list = true,
+    list_item = true,
+    section = true,
+    document = true,
+    fenced_code_block = true,
+    fenced_code_block_delimiter = true,
+  }
+
+  --- @param node TSNode
+  --- @return nvim.util.MDNode?
+  local function extract(node)
+    local ntype = node:type()
+
+    if ntype:match('^%p$') or contains(ntype, { 'block_continuation' }) then
+      return
+    end
+
+    --- @type table<any,any>
+    local ret = { type = ntype }
+
+    if not EXCLUDE_TEXT_TYPE[ntype] then
+      ret.text = vim.treesitter.get_node_text(node, text)
+    end
+
+    if ntype == 'inline' then
+      ret = parse_md_inline(ret.text)
+    end
+
+    for child, child_field in node:iter_children() do
+      local e = extract(child)
+      if child_field then
+        ret[child_field] = e
+      else
+        table.insert(ret, e)
+      end
+    end
+
+    return ret
+  end
+
+  return extract(root) or {}
+end
+
+--- Prefixes each line in `text`.
+---
+--- Does not wrap, not important for "meta" files? (You probably want md_to_vimdoc instead.)
+---
+--- @param text string
+--- @param prefix_ string
+function M.prefix_lines(prefix_, text)
+  local r = ''
+  for _, l in ipairs(vim.split(text, '\n', { plain = true })) do
+    r = r .. vim.trim(prefix_ .. l) .. '\n'
+  end
+  return r
+end
+
+--- @param x string
+--- @param start_indent integer
+--- @param indent integer
+--- @param text_width integer
+--- @return string
+function M.wrap(x, start_indent, indent, text_width)
+  local words = vim.split(vim.trim(x), '%s+')
+  local parts = { string.rep(' ', start_indent) } --- @type string[]
+  local count = indent
+
+  for i, w in ipairs(words) do
+    if count > indent and count + #w > text_width - 1 then
+      parts[#parts + 1] = '\n'
+      parts[#parts + 1] = string.rep(' ', indent)
+      count = indent
+    elseif i ~= 1 then
+      parts[#parts + 1] = ' '
+      count = count + 1
+    end
+    count = count + #w
+    parts[#parts + 1] = w
+  end
+
+  return (table.concat(parts):gsub('%s+\n', '\n'):gsub('\n+$', ''))
+end
+
+--- @param node nvim.util.MDNode
+--- @param start_indent integer
+--- @param indent integer
+--- @param text_width integer
+--- @param level integer
+--- @return string[]
+local function render_md(node, start_indent, indent, text_width, level, is_list)
+  local parts = {} --- @type string[]
+
+  -- For debugging
+  local add_tag = false
+  -- local add_tag = true
+
+  local ntype = node.type
+
+  if add_tag then
+    parts[#parts + 1] = '<' .. ntype .. '>'
+  end
+
+  if ntype == 'text' then
+    parts[#parts + 1] = node.text
+  elseif ntype == 'html_tag' then
+    error('html_tag: ' .. node.text)
+  elseif ntype == 'inline_link' then
+    vim.list_extend(parts, { '*', node[1].text, '*' })
+  elseif ntype == 'shortcut_link' then
+    if node[1].text:find('^<.*>$') then
+      parts[#parts + 1] = node[1].text
+    elseif node[1].text:find('^%d+$') then
+      vim.list_extend(parts, { '[', node[1].text, ']' })
+    else
+      vim.list_extend(parts, { '|', node[1].text, '|' })
+    end
+  elseif ntype == 'backslash_escape' then
+    parts[#parts + 1] = node.text
+  elseif ntype == 'emphasis' then
+    parts[#parts + 1] = node.text:sub(2, -2)
+  elseif ntype == 'code_span' then
+    vim.list_extend(parts, { '`', node.text:sub(2, -2):gsub(' ', NBSP), '`' })
+  elseif ntype == 'inline' then
+    if #node == 0 then
+      local text = assert(node.text)
+      parts[#parts + 1] = M.wrap(text, start_indent, indent, text_width)
+    else
+      for _, child in ipairs(node) do
+        vim.list_extend(parts, render_md(child, start_indent, indent, text_width, level + 1))
+      end
+    end
+  elseif ntype == 'paragraph' then
+    local pparts = {}
+    for _, child in ipairs(node) do
+      vim.list_extend(pparts, render_md(child, start_indent, indent, text_width, level + 1))
+    end
+    parts[#parts + 1] = M.wrap(table.concat(pparts), start_indent, indent, text_width)
+    parts[#parts + 1] = '\n'
+  elseif ntype == 'code_fence_content' then
+    local lines = vim.split(node.text:gsub('\n%s*$', ''), '\n')
+
+    local cindent = indent + INDENTATION
+    if level > 3 then
+      -- The tree-sitter markdown parser doesn't parse the code blocks indents
+      -- correctly in lists. Fudge it!
+      lines[1] = '    ' .. lines[1] -- ¯\_(ツ)_/¯
+      cindent = indent - level
+      local _, initial_indent = lines[1]:find('^%s*')
+      initial_indent = initial_indent + cindent
+      if initial_indent < indent then
+        cindent = indent - INDENTATION
+      end
+    end
+
+    for _, l in ipairs(lines) do
+      if #l > 0 then
+        parts[#parts + 1] = string.rep(' ', cindent)
+        parts[#parts + 1] = l
+      end
+      parts[#parts + 1] = '\n'
+    end
+  elseif ntype == 'fenced_code_block' then
+    parts[#parts + 1] = '>'
+    for _, child in ipairs(node) do
+      if child.type == 'info_string' then
+        parts[#parts + 1] = child.text
+        break
+      end
+    end
+    parts[#parts + 1] = '\n'
+    for _, child in ipairs(node) do
+      if child.type ~= 'info_string' then
+        vim.list_extend(parts, render_md(child, start_indent, indent, text_width, level + 1))
+      end
+    end
+    parts[#parts + 1] = '<\n'
+  elseif ntype == 'html_block' then
+    local text = node.text:gsub('^<pre>help', '')
+    text = text:gsub('</pre>%s*$', '')
+    parts[#parts + 1] = text
+  elseif ntype == 'list_marker_dot' then
+    parts[#parts + 1] = node.text
+  elseif contains(ntype, { 'list_marker_minus', 'list_marker_star' }) then
+    parts[#parts + 1] = '• '
+  elseif ntype == 'list_item' then
+    parts[#parts + 1] = string.rep(' ', indent)
+    local offset = node[1].type == 'list_marker_dot' and 3 or 2
+    for i, child in ipairs(node) do
+      local sindent = i <= 2 and 0 or (indent + offset)
+      vim.list_extend(
+        parts,
+        render_md(child, sindent, indent + offset, text_width, level + 1, true)
+      )
+    end
+  else
+    if node.text then
+      error(fmt('cannot render:\n%s', vim.inspect(node)))
+    end
+    for i, child in ipairs(node) do
+      local start_indent0 = i == 1 and start_indent or indent
+      vim.list_extend(
+        parts,
+        render_md(child, start_indent0, indent, text_width, level + 1, is_list)
+      )
+      if ntype ~= 'list' and i ~= #node then
+        if (node[i + 1] or {}).type ~= 'list' then
+          parts[#parts + 1] = '\n'
+        end
+      end
+    end
+  end
+
+  if add_tag then
+    parts[#parts + 1] = '</' .. ntype .. '>'
+  end
+
+  return parts
+end
+
+--- @param text_width integer
+local function align_tags(text_width)
+  --- @param line string
+  --- @return string
+  return function(line)
+    local tag_pat = '%s*(%*.+%*)%s*$'
+    local tags = {}
+    for m in line:gmatch(tag_pat) do
+      table.insert(tags, m)
+    end
+
+    if #tags > 0 then
+      line = line:gsub(tag_pat, '')
+      local tags_str = ' ' .. table.concat(tags, ' ')
+      --- @type integer
+      local conceal_offset = select(2, tags_str:gsub('%*', '')) - 2
+      local pad = string.rep(' ', text_width - #line - #tags_str + conceal_offset)
+      return line .. pad .. tags_str
+    end
+
+    return line
+  end
+end
+
+--- @param text string
+--- @param start_indent integer
+--- @param indent integer
+--- @param is_list? boolean
+--- @return string
+function M.md_to_vimdoc(text, start_indent, indent, text_width, is_list)
+  -- Add an extra newline so the parser can properly capture ending ```
+  local parsed = parse_md(text .. '\n')
+  local ret = render_md(parsed, start_indent, indent, text_width, 0, is_list)
+
+  local lines = vim.split(table.concat(ret):gsub(NBSP, ' '), '\n')
+
+  lines = vim.tbl_map(align_tags(text_width), lines)
+
+  local s = table.concat(lines, '\n')
+
+  -- Reduce whitespace in code-blocks
+  s = s:gsub('\n+%s*>([a-z]+)\n', ' >%1\n')
+  s = s:gsub('\n+%s*>\n?\n', ' >\n')
+
+  return s
+end
+
+return M