diff --git a/cmake.config/versiondef.h.in b/cmake.config/versiondef.h.in
index d03e56130c..9771e0d148 100644
--- a/cmake.config/versiondef.h.in
+++ b/cmake.config/versiondef.h.in
@@ -11,10 +11,6 @@
 # include "auto/versiondef_git.h"
 #endif
 
-#define NVIM_API_LEVEL @NVIM_API_LEVEL@
-#define NVIM_API_LEVEL_COMPAT @NVIM_API_LEVEL_COMPAT@
-#define NVIM_API_PRERELEASE @NVIM_API_PRERELEASE@
-
 #define NVIM_VERSION_CFLAGS "${VERSION_STRING}"
 #define NVIM_VERSION_BUILD_TYPE "$<CONFIG>"
 
diff --git a/scripts/gen_eval_files.lua b/scripts/gen_eval_files.lua
index 895033d5af..83e55b3bc4 100755
--- a/scripts/gen_eval_files.lua
+++ b/scripts/gen_eval_files.lua
@@ -2,7 +2,7 @@
 
 -- Generator for various vimdoc and Lua type files
 
-local DEP_API_METADATA = 'build/api_metadata.mpack'
+local DEP_API_METADATA = 'build/funcs_metadata.mpack'
 
 --- @class vim.api.metadata
 --- @field name string
diff --git a/src/nvim/CMakeLists.txt b/src/nvim/CMakeLists.txt
index 5ec0e4d9ec..047b22edcc 100644
--- a/src/nvim/CMakeLists.txt
+++ b/src/nvim/CMakeLists.txt
@@ -285,7 +285,8 @@ endif()
 # Variables
 #-------------------------------------------------------------------------------
 
-set(API_METADATA ${PROJECT_BINARY_DIR}/api_metadata.mpack)
+set(FUNCS_METADATA ${PROJECT_BINARY_DIR}/funcs_metadata.mpack)
+set(UI_METADATA ${PROJECT_BINARY_DIR}/ui_metadata.mpack)
 set(BINARY_LIB_DIR ${PROJECT_BINARY_DIR}/lib/nvim)
 set(GENERATED_DIR ${PROJECT_BINARY_DIR}/src/nvim/auto)
 set(GENERATED_INCLUDES_DIR ${PROJECT_BINARY_DIR}/include)
@@ -317,14 +318,13 @@ set(GENERATED_EVENTS_NAMES_MAP ${GENERATED_DIR}/auevents_name_map.generated.h)
 set(GENERATED_EX_CMDS_DEFS ${GENERATED_DIR}/ex_cmds_defs.generated.h)
 set(GENERATED_EX_CMDS_ENUM ${GENERATED_INCLUDES_DIR}/ex_cmds_enum.generated.h)
 set(GENERATED_FUNCS ${GENERATED_DIR}/funcs.generated.h)
-set(GENERATED_FUNCS_METADATA ${GENERATED_DIR}/api/private/funcs_metadata.generated.h)
+set(GENERATED_API_METADATA ${GENERATED_DIR}/api/private/api_metadata.generated.h)
 set(GENERATED_KEYSETS_DEFS ${GENERATED_DIR}/keysets_defs.generated.h)
 set(GENERATED_OPTIONS ${GENERATED_DIR}/options.generated.h)
 set(GENERATED_OPTIONS_ENUM ${GENERATED_DIR}/options_enum.generated.h)
 set(GENERATED_OPTIONS_MAP ${GENERATED_DIR}/options_map.generated.h)
 set(GENERATED_UI_EVENTS_CALL ${GENERATED_DIR}/ui_events_call.generated.h)
 set(GENERATED_UI_EVENTS_CLIENT ${GENERATED_DIR}/ui_events_client.generated.h)
-set(GENERATED_UI_EVENTS_METADATA ${GENERATED_DIR}/api/private/ui_events_metadata.generated.h)
 set(GENERATED_UI_EVENTS_REMOTE ${GENERATED_DIR}/ui_events_remote.generated.h)
 set(GENERATED_UNICODE_TABLES ${GENERATED_DIR}/unicode_tables.generated.h)
 set(LUA_API_C_BINDINGS ${GENERATED_DIR}/lua_api_c_bindings.generated.c)
@@ -493,7 +493,7 @@ add_custom_command(
     "${NVIM_VERSION_DEF_H}"
   DEPENDS "${PROJECT_BINARY_DIR}/cmake.config/auto/versiondef-$<CONFIG>.h")
 
-set(LUA_GEN ${LUA_GEN_PRG} ${GENERATOR_PRELOAD} ${PROJECT_SOURCE_DIR} $<TARGET_FILE:nlua0>)
+set(LUA_GEN ${LUA_GEN_PRG} ${GENERATOR_PRELOAD} ${PROJECT_SOURCE_DIR} $<TARGET_FILE:nlua0> ${PROJECT_BINARY_DIR})
 set(LUA_GEN_DEPS ${GENERATOR_PRELOAD} $<TARGET_FILE:nlua0>)
 
 # NVIM_GENERATED_FOR_HEADERS: generated headers to be included in headers
@@ -553,14 +553,19 @@ add_custom_command(OUTPUT ${GENERATED_UNICODE_TABLES}
     ${UNICODE_FILES}
 )
 
+set(NVIM_VERSION_LUA ${PROJECT_BINARY_DIR}/nvim_version.lua)
+configure_file(${GENERATOR_DIR}/nvim_version.lua.in ${NVIM_VERSION_LUA})
+
 add_custom_command(
-  OUTPUT ${GENERATED_API_DISPATCH} ${GENERATED_FUNCS_METADATA}
-         ${API_METADATA} ${LUA_API_C_BINDINGS} ${GENERATED_KEYSETS_DEFS}
+  OUTPUT ${GENERATED_API_DISPATCH} ${GENERATED_API_METADATA}
+  ${FUNCS_METADATA} ${LUA_API_C_BINDINGS} ${GENERATED_KEYSETS_DEFS}
          COMMAND ${LUA_GEN} ${API_DISPATCH_GENERATOR}
                          ${GENERATED_API_DISPATCH}
-                         ${GENERATED_FUNCS_METADATA} ${API_METADATA}
+                         ${GENERATED_API_METADATA} ${FUNCS_METADATA}
                          ${LUA_API_C_BINDINGS}
                          ${GENERATED_KEYSETS_DEFS}
+                         ${UI_METADATA}
+                         ${NVIM_VERSION_GIT_H}
                          ${API_HEADERS}
   DEPENDS
     ${LUA_GEN_DEPS}
@@ -568,6 +573,9 @@ add_custom_command(
     ${MSGPACK_RPC_HEADERS}
     ${API_DISPATCH_GENERATOR}
     ${GENERATOR_C_GRAMMAR}
+    ${UI_METADATA}
+    ${NVIM_VERSION_LUA}
+    ${NVIM_VERSION_GIT_H}
     ${CMAKE_CURRENT_LIST_DIR}/api/dispatch_deprecated.lua
 )
 
@@ -612,13 +620,13 @@ list(APPEND NVIM_GENERATED_SOURCES
 add_custom_command(
   OUTPUT ${GENERATED_UI_EVENTS_CALL}
          ${GENERATED_UI_EVENTS_REMOTE}
-         ${GENERATED_UI_EVENTS_METADATA}
+         ${UI_METADATA}
          ${GENERATED_UI_EVENTS_CLIENT}
   COMMAND ${LUA_GEN} ${API_UI_EVENTS_GENERATOR}
                      ${CMAKE_CURRENT_LIST_DIR}/api/ui_events.in.h
                      ${GENERATED_UI_EVENTS_CALL}
                      ${GENERATED_UI_EVENTS_REMOTE}
-                     ${GENERATED_UI_EVENTS_METADATA}
+                     ${UI_METADATA}
                      ${GENERATED_UI_EVENTS_CLIENT}
   DEPENDS
     ${LUA_GEN_DEPS}
@@ -654,8 +662,8 @@ add_custom_command(OUTPUT ${GENERATED_EX_CMDS_ENUM} ${GENERATED_EX_CMDS_DEFS}
 )
 
 add_custom_command(OUTPUT ${GENERATED_FUNCS} ${FUNCS_DATA}
-  COMMAND ${LUA_GEN} ${FUNCS_GENERATOR} ${GENERATED_DIR} ${API_METADATA} ${FUNCS_DATA}
-  DEPENDS ${LUA_GEN_DEPS} ${FUNCS_GENERATOR} ${CMAKE_CURRENT_LIST_DIR}/eval.lua ${API_METADATA}
+  COMMAND ${LUA_GEN} ${FUNCS_GENERATOR} ${GENERATED_DIR} ${FUNCS_METADATA} ${FUNCS_DATA}
+  DEPENDS ${LUA_GEN_DEPS} ${FUNCS_GENERATOR} ${CMAKE_CURRENT_LIST_DIR}/eval.lua ${FUNCS_METADATA}
 )
 list(APPEND NVIM_GENERATED_FOR_SOURCES
   "${GENERATED_FUNCS}")
@@ -931,7 +939,7 @@ add_custom_command(
     $<TARGET_FILE:nvim_bin> -l ${PROJECT_SOURCE_DIR}/scripts/gen_eval_files.lua
   DEPENDS
     nvim
-    ${API_METADATA}
+    ${FUNCS_METADATA}
     ${PROJECT_SOURCE_DIR}/scripts/gen_eval_files.lua
     ${PROJECT_SOURCE_DIR}/src/nvim/eval.lua
     ${PROJECT_SOURCE_DIR}/src/nvim/options.lua
diff --git a/src/nvim/api/private/helpers.c b/src/nvim/api/private/helpers.c
index 14f4046a56..97ba15e871 100644
--- a/src/nvim/api/private/helpers.c
+++ b/src/nvim/api/private/helpers.c
@@ -38,9 +38,8 @@
 #include "nvim/version.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
-# include "api/private/funcs_metadata.generated.h"
+# include "api/private/api_metadata.generated.h"
 # include "api/private/helpers.c.generated.h"
-# include "api/private/ui_events_metadata.generated.h"
 #endif
 
 /// Start block that may cause Vimscript exceptions while evaluating another code
@@ -653,83 +652,26 @@ void api_clear_error(Error *value)
 static ArenaMem mem_for_metadata = NULL;
 
 /// @returns a shared value. caller must not modify it!
-Dictionary api_metadata(void)
+Object api_metadata(void)
 {
-  static Dictionary metadata = ARRAY_DICT_INIT;
+  static Object metadata = OBJECT_INIT;
 
-  if (!metadata.size) {
+  if (metadata.type == kObjectTypeNil) {
     Arena arena = ARENA_EMPTY;
     Error err = ERROR_INIT;
-    metadata = arena_dict(&arena, 6);
-    PUT_C(metadata, "version", DICTIONARY_OBJ(version_dict(&arena)));
-    PUT_C(metadata, "functions",
-          unpack((char *)funcs_metadata, sizeof(funcs_metadata), &arena, &err));
-    if (ERROR_SET(&err)) {
+    metadata = unpack((char *)packed_api_metadata, sizeof(packed_api_metadata), &arena, &err);
+    if (ERROR_SET(&err) || metadata.type != kObjectTypeDictionary) {
       abort();
     }
-    PUT_C(metadata, "ui_events",
-          unpack((char *)ui_events_metadata, sizeof(ui_events_metadata), &arena, &err));
-    if (ERROR_SET(&err)) {
-      abort();
-    }
-    PUT_C(metadata, "ui_options", ARRAY_OBJ(ui_options_metadata(&arena)));
-    PUT_C(metadata, "error_types", DICTIONARY_OBJ(error_type_metadata(&arena)));
-    PUT_C(metadata, "types", DICTIONARY_OBJ(type_metadata(&arena)));
     mem_for_metadata = arena_finish(&arena);
   }
 
   return metadata;
 }
 
-static Array ui_options_metadata(Arena *arena)
+String api_metadata_raw(void)
 {
-  Array ui_options = arena_array(arena, kUIExtCount + 1);
-  ADD_C(ui_options, CSTR_AS_OBJ("rgb"));
-  for (UIExtension i = 0; i < kUIExtCount; i++) {
-    if (ui_ext_names[i][0] != '_') {
-      ADD_C(ui_options, CSTR_AS_OBJ(ui_ext_names[i]));
-    }
-  }
-  return ui_options;
-}
-
-static Dictionary error_type_metadata(Arena *arena)
-{
-  Dictionary types = arena_dict(arena, 2);
-
-  Dictionary exception_metadata = arena_dict(arena, 1);
-  PUT_C(exception_metadata, "id", INTEGER_OBJ(kErrorTypeException));
-
-  Dictionary validation_metadata = arena_dict(arena, 1);
-  PUT_C(validation_metadata, "id", INTEGER_OBJ(kErrorTypeValidation));
-
-  PUT_C(types, "Exception", DICTIONARY_OBJ(exception_metadata));
-  PUT_C(types, "Validation", DICTIONARY_OBJ(validation_metadata));
-
-  return types;
-}
-
-static Dictionary type_metadata(Arena *arena)
-{
-  Dictionary types = arena_dict(arena, 3);
-
-  Dictionary buffer_metadata = arena_dict(arena, 2);
-  PUT_C(buffer_metadata, "id", INTEGER_OBJ(kObjectTypeBuffer - EXT_OBJECT_TYPE_SHIFT));
-  PUT_C(buffer_metadata, "prefix", CSTR_AS_OBJ("nvim_buf_"));
-
-  Dictionary window_metadata = arena_dict(arena, 2);
-  PUT_C(window_metadata, "id", INTEGER_OBJ(kObjectTypeWindow - EXT_OBJECT_TYPE_SHIFT));
-  PUT_C(window_metadata, "prefix", CSTR_AS_OBJ("nvim_win_"));
-
-  Dictionary tabpage_metadata = arena_dict(arena, 2);
-  PUT_C(tabpage_metadata, "id", INTEGER_OBJ(kObjectTypeTabpage - EXT_OBJECT_TYPE_SHIFT));
-  PUT_C(tabpage_metadata, "prefix", CSTR_AS_OBJ("nvim_tabpage_"));
-
-  PUT_C(types, "Buffer", DICTIONARY_OBJ(buffer_metadata));
-  PUT_C(types, "Window", DICTIONARY_OBJ(window_metadata));
-  PUT_C(types, "Tabpage", DICTIONARY_OBJ(tabpage_metadata));
-
-  return types;
+  return cbuf_as_string((char *)packed_api_metadata, sizeof(packed_api_metadata));
 }
 
 // all the copy_[object] functions allow arena=NULL,
diff --git a/src/nvim/api/ui.h b/src/nvim/api/ui.h
index 9147f1d870..cdccc27ba4 100644
--- a/src/nvim/api/ui.h
+++ b/src/nvim/api/ui.h
@@ -7,6 +7,20 @@
 #include "nvim/types_defs.h"  // IWYU pragma: keep
 #include "nvim/ui_defs.h"  // IWYU pragma: keep
 
+/// Keep in sync with UIExtension in ui_defs.h
+EXTERN const char *ui_ext_names[] INIT( = {
+  "ext_cmdline",
+  "ext_popupmenu",
+  "ext_tabline",
+  "ext_wildmenu",
+  "ext_messages",
+  "ext_linegrid",
+  "ext_multigrid",
+  "ext_hlstate",
+  "ext_termcolors",
+  "_debug_float",
+});
+
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "api/ui.h.generated.h"
 # include "ui_events_remote.h.generated.h"
diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index 54bf290e6b..6a3c6bab67 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -1529,7 +1529,7 @@ Array nvim_get_api_info(uint64_t channel_id, Arena *arena)
 
   assert(channel_id <= INT64_MAX);
   ADD_C(rv, INTEGER_OBJ((int64_t)channel_id));
-  ADD_C(rv, DICTIONARY_OBJ(api_metadata()));
+  ADD_C(rv, api_metadata());
 
   return rv;
 }
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index 2e2640604b..c16fc1d708 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -442,8 +442,7 @@ static void f_and(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
 /// "api_info()" function
 static void f_api_info(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
 {
-  Dictionary metadata = api_metadata();
-  object_to_vim(DICTIONARY_OBJ(metadata), rettv, NULL);
+  object_to_vim(api_metadata(), rettv, NULL);
 }
 
 /// "atan2()" function
diff --git a/src/nvim/generators/gen_api_dispatch.lua b/src/nvim/generators/gen_api_dispatch.lua
index 56331e4162..78a83445af 100644
--- a/src/nvim/generators/gen_api_dispatch.lua
+++ b/src/nvim/generators/gen_api_dispatch.lua
@@ -2,15 +2,18 @@ local mpack = vim.mpack
 
 local hashy = require 'generators.hashy'
 
-assert(#arg >= 5)
+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 (funcs_metadata.generated.h)
-local funcs_metadata_outputf = arg[2]
+-- 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 (api_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 = {}
 
@@ -96,8 +99,10 @@ local function add_keyset(val)
   })
 end
 
+local ui_options_text = nil
+
 -- read each input file, parse and append to the api metadata
-for i = 6, #arg do
+for i = pre_args + 1, #arg do
   local full_path = arg[i]
   local parts = {}
   for part in string.gmatch(full_path, '[^/]+') do
@@ -107,17 +112,18 @@ for i = 6, #arg do
 
   local input = assert(io.open(full_path, 'rb'))
 
-  local tmp = c_grammar.grammar:match(input:read('*all'))
+  local text = input:read('*all')
+  local tmp = c_grammar.grammar:match(text)
   for j = 1, #tmp do
     local val = tmp[j]
-    if val[1] ~= 'empty' then
-      if val.keyset_name then
-        add_keyset(val)
-      else
-        add_function(val)
-      end
+    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
 
@@ -218,13 +224,71 @@ for _, f in ipairs(functions) do
   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'
+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 funcs_metadata_output = assert(io.open(funcs_metadata_outputf, 'wb'))
-local packed = mpack.encode(exported_functions)
+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 placholder vim.NIL (than invalid mpack data)
+  put(item[1], item[2] or vim.NIL)
+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('generators.dump_bin_array')
-dump_bin_array(funcs_metadata_output, 'funcs_metadata', packed)
-funcs_metadata_output:close()
+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'))
diff --git a/src/nvim/generators/gen_api_ui_events.lua b/src/nvim/generators/gen_api_ui_events.lua
index 697626b793..a4f59c7209 100644
--- a/src/nvim/generators/gen_api_ui_events.lua
+++ b/src/nvim/generators/gen_api_ui_events.lua
@@ -204,7 +204,5 @@ for _, ev in ipairs(events) do
   end
 end
 
-local packed = mpack.encode(exported_events)
-local dump_bin_array = require('generators.dump_bin_array')
-dump_bin_array(metadata_output, 'ui_events_metadata', packed)
+metadata_output:write(mpack.encode(exported_events))
 metadata_output:close()
diff --git a/src/nvim/generators/nvim_version.lua.in b/src/nvim/generators/nvim_version.lua.in
new file mode 100644
index 0000000000..d0dbf77922
--- /dev/null
+++ b/src/nvim/generators/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/nvim/generators/preload.lua b/src/nvim/generators/preload.lua
index 721d2880b8..e14671074c 100644
--- a/src/nvim/generators/preload.lua
+++ b/src/nvim/generators/preload.lua
@@ -1,10 +1,13 @@
 local srcdir = table.remove(arg, 1)
 local nlualib = table.remove(arg, 1)
+local gendir = table.remove(arg, 1)
 package.path = srcdir .. '/src/nvim/?.lua;' .. srcdir .. '/runtime/lua/?.lua;' .. package.path
+package.path = 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/nvim/lua/executor.c b/src/nvim/lua/executor.c
index 3859dd922a..1a9bd026b5 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -15,6 +15,7 @@
 #include "nvim/api/extmark.h"
 #include "nvim/api/private/defs.h"
 #include "nvim/api/private/helpers.h"
+#include "nvim/api/ui.h"
 #include "nvim/ascii_defs.h"
 #include "nvim/buffer_defs.h"
 #include "nvim/change.h"
diff --git a/src/nvim/main.c b/src/nvim/main.c
index c2445437e6..6b862f2ed9 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -1103,20 +1103,16 @@ static void command_line_scan(mparm_T *parmp)
           FileDescriptor fp;
           const int fof_ret = file_open_fd(&fp, STDOUT_FILENO,
                                            kFileWriteOnly);
-          msgpack_packer *p = msgpack_packer_new(&fp, msgpack_file_write);
-
           if (fof_ret != 0) {
             semsg(_("E5421: Failed to open stdin: %s"), os_strerror(fof_ret));
           }
 
-          if (p == NULL) {
-            emsg(_(e_outofmem));
+          String data = api_metadata_raw();
+          const ptrdiff_t written_bytes = file_write(&fp, data.data, data.size);
+          if (written_bytes < 0) {
+            msgpack_file_write_error((int)written_bytes);
           }
 
-          Object md = DICTIONARY_OBJ(api_metadata());
-          msgpack_rpc_from_object(&md, p);
-
-          msgpack_packer_free(p);
           const int ff_ret = file_flush(&fp);
           if (ff_ret < 0) {
             msgpack_file_write_error(ff_ret);
diff --git a/src/nvim/os/fileio.c b/src/nvim/os/fileio.c
index e14de9e5db..da6fb13768 100644
--- a/src/nvim/os/fileio.c
+++ b/src/nvim/os/fileio.c
@@ -366,24 +366,6 @@ ptrdiff_t file_skip(FileDescriptor *const fp, const size_t size)
   return (ptrdiff_t)read_bytes;
 }
 
-/// Msgpack callback for writing to a file
-///
-/// @param  data  File to write to.
-/// @param[in]  buf  Data to write.
-/// @param[in]  len  Length of the data to write.
-///
-/// @return 0 in case of success, -1 in case of error.
-int msgpack_file_write(void *data, const char *buf, size_t len)
-  FUNC_ATTR_NONNULL_ALL FUNC_ATTR_WARN_UNUSED_RESULT
-{
-  assert(len < PTRDIFF_MAX);
-  const ptrdiff_t written_bytes = file_write((FileDescriptor *)data, buf, len);
-  if (written_bytes < 0) {
-    return msgpack_file_write_error((int)written_bytes);
-  }
-  return 0;
-}
-
 /// Print error which occurs when failing to write msgpack data
 ///
 /// @param[in]  error  Error code of the error to print.
diff --git a/src/nvim/ui.h b/src/nvim/ui.h
index ef75bf62d9..52b1334b15 100644
--- a/src/nvim/ui.h
+++ b/src/nvim/ui.h
@@ -10,20 +10,6 @@
 #include "nvim/types_defs.h"  // IWYU pragma: keep
 #include "nvim/ui_defs.h"  // IWYU pragma: keep
 
-/// Keep in sync with UIExtension in ui_defs.h
-EXTERN const char *ui_ext_names[] INIT( = {
-  "ext_cmdline",
-  "ext_popupmenu",
-  "ext_tabline",
-  "ext_wildmenu",
-  "ext_messages",
-  "ext_linegrid",
-  "ext_multigrid",
-  "ext_hlstate",
-  "ext_termcolors",
-  "_debug_float",
-});
-
 // uncrustify:off
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "ui.h.generated.h"
diff --git a/src/nvim/version.c b/src/nvim/version.c
index a3f825c324..038c9701bf 100644
--- a/src/nvim/version.c
+++ b/src/nvim/version.c
@@ -2550,24 +2550,6 @@ bool has_vim_patch(int n)
   return false;
 }
 
-Dictionary version_dict(Arena *arena)
-{
-  Dictionary d = arena_dict(arena, 8);
-  PUT_C(d, "major", INTEGER_OBJ(NVIM_VERSION_MAJOR));
-  PUT_C(d, "minor", INTEGER_OBJ(NVIM_VERSION_MINOR));
-  PUT_C(d, "patch", INTEGER_OBJ(NVIM_VERSION_PATCH));
-#ifndef NVIM_VERSION_BUILD
-  PUT_C(d, "build", NIL);
-#else
-  PUT_C(d, "build", STATIC_CSTR_AS_OBJ(NVIM_VERSION_BUILD));
-#endif
-  PUT_C(d, "prerelease", BOOLEAN_OBJ(NVIM_VERSION_PRERELEASE[0] != '\0'));
-  PUT_C(d, "api_level", INTEGER_OBJ(NVIM_API_LEVEL));
-  PUT_C(d, "api_compatible", INTEGER_OBJ(NVIM_API_LEVEL_COMPAT));
-  PUT_C(d, "api_prerelease", BOOLEAN_OBJ(NVIM_API_PRERELEASE));
-  return d;
-}
-
 void ex_version(exarg_T *eap)
 {
   // Ignore a ":version 9.99" command.
diff --git a/test/unit/os/fileio_spec.lua b/test/unit/os/fileio_spec.lua
index cc5a0d84c3..617141fd3a 100644
--- a/test/unit/os/fileio_spec.lua
+++ b/test/unit/os/fileio_spec.lua
@@ -65,10 +65,6 @@ local function file_write(fp, buf)
   return m.file_write(fp, buf, #buf)
 end
 
-local function msgpack_file_write(fp, buf)
-  return m.msgpack_file_write(fp, buf, #buf)
-end
-
 local function file_read(fp, size)
   local buf = nil
   if size == nil then
@@ -391,18 +387,6 @@ describe('file_write', function()
   end)
 end)
 
-describe('msgpack_file_write', function()
-  itp('can write the whole file at once', function()
-    local err, fp = file_open(filec, m.kFileCreateOnly, 384)
-    eq(0, err)
-    eq(true, fp.wr)
-    local wr = msgpack_file_write(fp, fcontents)
-    eq(0, wr)
-    eq(0, m.file_close(fp, false))
-    eq(fcontents, io.open(filec):read('*a'))
-  end)
-end)
-
 describe('file_skip', function()
   itp('can skip 3 bytes', function()
     local err, fp = file_open(file1, 0, 384)