diff --git a/Makefile b/Makefile
index c0262033cf..662c334c0c 100644
--- a/Makefile
+++ b/Makefile
@@ -148,7 +148,6 @@ iwyu: build/.ran-cmake
 	|src/nvim/buffer_defs.h\
 	|src/nvim/channel.h\
 	|src/nvim/charset.h\
-	|src/nvim/drawline.h\
 	|src/nvim/eval.h\
 	|src/nvim/eval/encode.h\
 	|src/nvim/eval/typval.h\
diff --git a/src/clint.py b/src/clint.py
index 51155f0038..80ebf565a1 100755
--- a/src/clint.py
+++ b/src/clint.py
@@ -906,7 +906,6 @@ def CheckIncludes(filename, lines, error):
             "src/nvim/buffer_defs.h",
             "src/nvim/channel.h",
             "src/nvim/charset.h",
-            "src/nvim/drawline.h",
             "src/nvim/eval.h",
             "src/nvim/eval/encode.h",
             "src/nvim/eval/typval.h",
diff --git a/src/nvim/api/buffer.c b/src/nvim/api/buffer.c
index 99d261e73d..bbb6b92986 100644
--- a/src/nvim/api/buffer.c
+++ b/src/nvim/api/buffer.c
@@ -18,7 +18,6 @@
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
 #include "nvim/buffer.h"
-#include "nvim/buffer_defs.h"
 #include "nvim/buffer_updates.h"
 #include "nvim/change.h"
 #include "nvim/cursor.h"
diff --git a/src/nvim/api/buffer.h b/src/nvim/api/buffer.h
index f3971c1d30..fe2d104058 100644
--- a/src/nvim/api/buffer.h
+++ b/src/nvim/api/buffer.h
@@ -5,7 +5,8 @@
 
 #include "nvim/api/keysets_defs.h"  // IWYU pragma: keep
 #include "nvim/api/private/defs.h"  // IWYU pragma: keep
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/pos_defs.h"  // IWYU pragma: keep
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "api/buffer.h.generated.h"
diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index aed286165a..9ae5244fa1 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -64,7 +64,6 @@
 #include "nvim/statusline.h"
 #include "nvim/strings.h"
 #include "nvim/terminal.h"
-#include "nvim/types_defs.h"
 #include "nvim/ui.h"
 #include "nvim/vim_defs.h"
 #include "nvim/window.h"
diff --git a/src/nvim/base64.c b/src/nvim/base64.c
index a0ba219fa2..7f7d121442 100644
--- a/src/nvim/base64.c
+++ b/src/nvim/base64.c
@@ -3,6 +3,7 @@
 #include <stdint.h>
 #include <string.h>
 
+#include "auto/config.h"
 #include "nvim/base64.h"
 #include "nvim/memory.h"
 
diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index c9ae4c3ed3..d62e73a191 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -94,7 +94,6 @@
 #include "nvim/strings.h"
 #include "nvim/syntax.h"
 #include "nvim/terminal.h"
-#include "nvim/types_defs.h"
 #include "nvim/ui.h"
 #include "nvim/undo.h"
 #include "nvim/usercmd.h"
diff --git a/src/nvim/buffer_defs.h b/src/nvim/buffer_defs.h
index 49d2126801..3a6b5e2c6b 100644
--- a/src/nvim/buffer_defs.h
+++ b/src/nvim/buffer_defs.h
@@ -24,7 +24,7 @@
 #include "nvim/regexp_defs.h"
 #include "nvim/sign_defs.h"
 #include "nvim/statusline_defs.h"
-#include "nvim/terminal.h"
+#include "nvim/types_defs.h"
 #include "nvim/undo_defs.h"
 
 /// Reference to a buffer that stores the value of buf_free_count.
diff --git a/src/nvim/bufwrite.c b/src/nvim/bufwrite.c
index 67e5fb3b6f..c506cfdfa3 100644
--- a/src/nvim/bufwrite.c
+++ b/src/nvim/bufwrite.c
@@ -13,12 +13,10 @@
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
 #include "nvim/buffer.h"
-#include "nvim/buffer_defs.h"
 #include "nvim/bufwrite.h"
 #include "nvim/change.h"
 #include "nvim/drawscreen.h"
 #include "nvim/eval.h"
-#include "nvim/eval/typval_defs.h"
 #include "nvim/ex_cmds.h"
 #include "nvim/ex_cmds_defs.h"
 #include "nvim/ex_eval.h"
diff --git a/src/nvim/bufwrite.h b/src/nvim/bufwrite.h
index 9ed6216847..ce9e04d2b1 100644
--- a/src/nvim/bufwrite.h
+++ b/src/nvim/bufwrite.h
@@ -1,8 +1,8 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 #include "nvim/pos_defs.h"  // IWYU pragma: keep
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "bufwrite.h.generated.h"
diff --git a/src/nvim/change.c b/src/nvim/change.c
index 0154ead8fb..290f527946 100644
--- a/src/nvim/change.c
+++ b/src/nvim/change.c
@@ -9,7 +9,6 @@
 #include "nvim/assert_defs.h"
 #include "nvim/autocmd.h"
 #include "nvim/buffer.h"
-#include "nvim/buffer_defs.h"
 #include "nvim/buffer_updates.h"
 #include "nvim/change.h"
 #include "nvim/charset.h"
diff --git a/src/nvim/change.h b/src/nvim/change.h
index 06155b6da6..bd1094d57e 100644
--- a/src/nvim/change.h
+++ b/src/nvim/change.h
@@ -1,7 +1,9 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include <stddef.h>  // IWYU pragma: keep
+
 #include "nvim/pos_defs.h"  // IWYU pragma: keep
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 
 /// flags for open_line()
 enum {
diff --git a/src/nvim/channel.h b/src/nvim/channel.h
index 2b6356b216..7e3e84d918 100644
--- a/src/nvim/channel.h
+++ b/src/nvim/channel.h
@@ -17,7 +17,6 @@
 #include "nvim/map_defs.h"
 #include "nvim/msgpack_rpc/channel_defs.h"
 #include "nvim/os/pty_process.h"
-#include "nvim/terminal.h"
 #include "nvim/types_defs.h"
 
 static inline bool callback_reader_set(CallbackReader reader)
diff --git a/src/nvim/cursor.h b/src/nvim/cursor.h
index d50976b598..19107dfec9 100644
--- a/src/nvim/cursor.h
+++ b/src/nvim/cursor.h
@@ -1,7 +1,7 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/pos_defs.h"  // IWYU pragma: keep
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "cursor.h.generated.h"
diff --git a/src/nvim/decoration.c b/src/nvim/decoration.c
index a18f30ed41..7b3a32167e 100644
--- a/src/nvim/decoration.c
+++ b/src/nvim/decoration.c
@@ -20,7 +20,6 @@
 #include "nvim/move.h"
 #include "nvim/option_vars.h"
 #include "nvim/pos_defs.h"
-#include "nvim/sign.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "decoration.c.generated.h"
diff --git a/src/nvim/decoration.h b/src/nvim/decoration.h
index 1c072eab20..d8fd432880 100644
--- a/src/nvim/decoration.h
+++ b/src/nvim/decoration.h
@@ -5,11 +5,11 @@
 #include <stdint.h>
 
 #include "klib/kvec.h"
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/decoration_defs.h"  // IWYU pragma: export
 #include "nvim/macros_defs.h"
 #include "nvim/marktree_defs.h"
 #include "nvim/pos_defs.h"  // IWYU pragma: keep
+#include "nvim/sign_defs.h"  // IWYU pragma: keep
 #include "nvim/types_defs.h"
 
 // actual Decor* data is in decoration_defs.h
diff --git a/src/nvim/decoration_defs.h b/src/nvim/decoration_defs.h
index 6e7dc08f80..f272753f46 100644
--- a/src/nvim/decoration_defs.h
+++ b/src/nvim/decoration_defs.h
@@ -125,3 +125,21 @@ typedef struct {
 
 // initializes in a valid state for the DecorHighlightInline branch
 #define DECOR_INLINE_INIT { .ext = false, .data.hl = DECOR_HIGHLIGHT_INLINE_INIT }
+
+typedef struct {
+  NS ns_id;
+  bool active;
+  LuaRef redraw_start;
+  LuaRef redraw_buf;
+  LuaRef redraw_win;
+  LuaRef redraw_line;
+  LuaRef redraw_end;
+  LuaRef hl_def;
+  LuaRef spell_nav;
+  int hl_valid;
+  bool hl_cached;
+
+  uint8_t error_count;
+} DecorProvider;
+
+typedef kvec_withinit_t(DecorProvider *, 4) DecorProviders;
diff --git a/src/nvim/decoration_provider.c b/src/nvim/decoration_provider.c
index 172eb569c9..39516ff541 100644
--- a/src/nvim/decoration_provider.c
+++ b/src/nvim/decoration_provider.c
@@ -1,5 +1,6 @@
 #include <assert.h>
 #include <lauxlib.h>
+#include <stdint.h>
 #include <string.h>
 
 #include "klib/kvec.h"
@@ -8,6 +9,7 @@
 #include "nvim/api/private/helpers.h"
 #include "nvim/buffer_defs.h"
 #include "nvim/decoration.h"
+#include "nvim/decoration_defs.h"
 #include "nvim/decoration_provider.h"
 #include "nvim/globals.h"
 #include "nvim/highlight.h"
@@ -16,6 +18,12 @@
 #include "nvim/message.h"
 #include "nvim/pos_defs.h"
 
+#ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "decoration_provider.c.generated.h"
+#endif
+
+enum { DP_MAX_ERROR = 3, };
+
 static kvec_t(DecorProvider) decor_providers = KV_INITIAL_VALUE;
 
 #define DECORATION_PROVIDER_INIT(ns_id) (DecorProvider) \
diff --git a/src/nvim/decoration_provider.h b/src/nvim/decoration_provider.h
index e0dd67a6f7..ad6fb7ac19 100644
--- a/src/nvim/decoration_provider.h
+++ b/src/nvim/decoration_provider.h
@@ -1,32 +1,10 @@
 #pragma once
 
 #include <stdbool.h>
-#include <stdint.h>
 
-#include "klib/kvec.h"
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/decoration_defs.h"  // IWYU pragma: keep
 #include "nvim/macros_defs.h"
-#include "nvim/types_defs.h"
-
-#define DP_MAX_ERROR 3
-
-typedef struct {
-  NS ns_id;
-  bool active;
-  LuaRef redraw_start;
-  LuaRef redraw_buf;
-  LuaRef redraw_win;
-  LuaRef redraw_line;
-  LuaRef redraw_end;
-  LuaRef hl_def;
-  LuaRef spell_nav;
-  int hl_valid;
-  bool hl_cached;
-
-  uint8_t error_count;
-} DecorProvider;
-
-typedef kvec_withinit_t(DecorProvider *, 4) DecorProviders;
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 
 EXTERN bool provider_active INIT( = false);
 
diff --git a/src/nvim/digraph.h b/src/nvim/digraph.h
index 267004124b..a3782cdd58 100644
--- a/src/nvim/digraph.h
+++ b/src/nvim/digraph.h
@@ -1,6 +1,5 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 #include "nvim/garray_defs.h"  // IWYU pragma: keep
diff --git a/src/nvim/drawline.c b/src/nvim/drawline.c
index ee1cd0a3ce..4f62fda2c5 100644
--- a/src/nvim/drawline.c
+++ b/src/nvim/drawline.c
@@ -15,6 +15,7 @@
 #include "nvim/cursor.h"
 #include "nvim/cursor_shape.h"
 #include "nvim/decoration.h"
+#include "nvim/decoration_defs.h"
 #include "nvim/decoration_provider.h"
 #include "nvim/diff.h"
 #include "nvim/drawline.h"
diff --git a/src/nvim/drawline.h b/src/nvim/drawline.h
index 5a7f220a13..97a6ca2eee 100644
--- a/src/nvim/drawline.h
+++ b/src/nvim/drawline.h
@@ -4,14 +4,13 @@
 #include <stdint.h>
 
 #include "klib/kvec.h"
-#include "nvim/decoration_provider.h"
-#include "nvim/fold_defs.h"
+#include "nvim/decoration_defs.h"  // IWYU pragma: keep
+#include "nvim/fold_defs.h"  // IWYU pragma: keep
 #include "nvim/macros_defs.h"
 #include "nvim/pos_defs.h"
 #include "nvim/types_defs.h"
 
-// Maximum columns for terminal highlight attributes
-#define TERM_ATTRS_MAX 1024
+enum { TERM_ATTRS_MAX = 1024, };  ///< Maximum columns for terminal highlight attributes
 
 typedef struct {
   NS ns_id;
@@ -23,7 +22,7 @@ EXTERN kvec_t(WinExtmark) win_extmark_arr INIT( = KV_INITIAL_VALUE);
 
 EXTERN bool conceal_cursor_used INIT( = false);
 
-// Spell checking variables passed from win_update() to win_line().
+/// Spell checking variables passed from win_update() to win_line().
 typedef struct {
   bool spv_has_spell;         ///< drawn window has spell checking
   bool spv_unchanged;         ///< not updating for changed text
diff --git a/src/nvim/drawscreen.c b/src/nvim/drawscreen.c
index 9a5cfc7d07..8a441901d9 100644
--- a/src/nvim/drawscreen.c
+++ b/src/nvim/drawscreen.c
@@ -105,7 +105,6 @@
 #include "nvim/strings.h"
 #include "nvim/syntax.h"
 #include "nvim/terminal.h"
-#include "nvim/types_defs.h"
 #include "nvim/ui.h"
 #include "nvim/ui_compositor.h"
 #include "nvim/version.h"
diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index 0fcb665f0f..613aa2a591 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -18,7 +18,6 @@
 #include "nvim/drawscreen.h"
 #include "nvim/edit.h"
 #include "nvim/eval.h"
-#include "nvim/eval/typval_defs.h"
 #include "nvim/ex_cmds_defs.h"
 #include "nvim/ex_docmd.h"
 #include "nvim/extmark.h"
diff --git a/src/nvim/edit.h b/src/nvim/edit.h
index 434b653f7b..2f15e737be 100644
--- a/src/nvim/edit.h
+++ b/src/nvim/edit.h
@@ -1,8 +1,8 @@
 #pragma once
 
 #include "nvim/autocmd_defs.h"  // IWYU pragma: keep
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/pos_defs.h"  // IWYU pragma: keep
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 
 /// Values for in_cinkeys()
 enum {
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 21bb325e37..d12a49e7d4 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -16,7 +16,6 @@
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
 #include "nvim/buffer.h"
-#include "nvim/buffer_defs.h"
 #include "nvim/channel.h"
 #include "nvim/charset.h"
 #include "nvim/cmdexpand_defs.h"
diff --git a/src/nvim/eval.h b/src/nvim/eval.h
index 65f7020295..b350b9a8d1 100644
--- a/src/nvim/eval.h
+++ b/src/nvim/eval.h
@@ -4,18 +4,19 @@
 #include <stddef.h>
 #include <stdint.h>
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/channel.h"
 #include "nvim/cmdexpand_defs.h"  // IWYU pragma: keep
 #include "nvim/eval/typval_defs.h"
 #include "nvim/event/time.h"
 #include "nvim/ex_cmds_defs.h"
+#include "nvim/grid_defs.h"  // IWYU pragma: keep
 #include "nvim/hashtab_defs.h"
 #include "nvim/macros_defs.h"
 #include "nvim/mbyte_defs.h"  // IWYU pragma: keep
 #include "nvim/option_defs.h"  // IWYU pragma: keep
 #include "nvim/os/fileio_defs.h"  // IWYU pragma: keep
 #include "nvim/os/stdpaths_defs.h"  // IWYU pragma: keep
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 #include "nvim/vim_defs.h"  // IWYU pragma: keep
 
 #define COPYID_INC 2
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index f13235c3e9..5b6904269d 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -28,7 +28,6 @@
 #include "nvim/assert_defs.h"
 #include "nvim/autocmd.h"
 #include "nvim/buffer.h"
-#include "nvim/buffer_defs.h"
 #include "nvim/channel.h"
 #include "nvim/charset.h"
 #include "nvim/cmdexpand.h"
diff --git a/src/nvim/eval/funcs.h b/src/nvim/eval/funcs.h
index 0c345dacb4..e3a574b233 100644
--- a/src/nvim/eval/funcs.h
+++ b/src/nvim/eval/funcs.h
@@ -3,7 +3,6 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/cmdexpand_defs.h"  // IWYU pragma: keep
 #include "nvim/eval/typval_defs.h"
 #include "nvim/pos_defs.h"  // IWYU pragma: keep
diff --git a/src/nvim/ex_cmds2.h b/src/nvim/ex_cmds2.h
index 4f41f2cc41..a35a27758c 100644
--- a/src/nvim/ex_cmds2.h
+++ b/src/nvim/ex_cmds2.h
@@ -1,7 +1,7 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 
 /// flags for check_changed()
 enum {
diff --git a/src/nvim/extmark.h b/src/nvim/extmark.h
index e83c8d1257..2f2491f8a4 100644
--- a/src/nvim/extmark.h
+++ b/src/nvim/extmark.h
@@ -4,11 +4,11 @@
 #include <stdint.h>
 
 #include "klib/kvec.h"
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/extmark_defs.h"  // IWYU pragma: export
 #include "nvim/macros_defs.h"
 #include "nvim/marktree_defs.h"
 #include "nvim/pos_defs.h"
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 
 EXTERN int curbuf_splice_pending INIT( = 0);
 
diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index 066a150f5a..3e8c4f694c 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -19,7 +19,6 @@
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
 #include "nvim/buffer.h"
-#include "nvim/buffer_defs.h"
 #include "nvim/buffer_updates.h"
 #include "nvim/change.h"
 #include "nvim/cursor.h"
diff --git a/src/nvim/fileio.h b/src/nvim/fileio.h
index 32a5ec3002..26161c03ba 100644
--- a/src/nvim/fileio.h
+++ b/src/nvim/fileio.h
@@ -4,12 +4,13 @@
 #include <stdio.h>  // IWYU pragma: keep
 #include <time.h>  // IWYU pragma: keep
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/eval/typval_defs.h"
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 #include "nvim/garray_defs.h"  // IWYU pragma: keep
 #include "nvim/os/fs_defs.h"  // IWYU pragma: keep
+#include "nvim/os/os_defs.h"  // IWYU pragma: keep
 #include "nvim/pos_defs.h"  // IWYU pragma: keep
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 
 /// Values for readfile() flags
 enum {
diff --git a/src/nvim/fold.h b/src/nvim/fold.h
index efa239daa5..887787578e 100644
--- a/src/nvim/fold.h
+++ b/src/nvim/fold.h
@@ -2,7 +2,8 @@
 
 #include <stdio.h>  // IWYU pragma: keep
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/decoration_defs.h"  // IWYU pragma: keep
+#include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
 #include "nvim/fold_defs.h"  // IWYU pragma: export
 #include "nvim/garray_defs.h"  // IWYU pragma: keep
 #include "nvim/macros_defs.h"
diff --git a/src/nvim/highlight.c b/src/nvim/highlight.c
index 6684a20607..cffa362d6a 100644
--- a/src/nvim/highlight.c
+++ b/src/nvim/highlight.c
@@ -11,6 +11,7 @@
 #include "nvim/api/private/helpers.h"
 #include "nvim/api/private/validate.h"
 #include "nvim/api/ui.h"
+#include "nvim/decoration_defs.h"
 #include "nvim/decoration_provider.h"
 #include "nvim/drawscreen.h"
 #include "nvim/gettext.h"
diff --git a/src/nvim/indent.h b/src/nvim/indent.h
index b64015958c..54d27e6243 100644
--- a/src/nvim/indent.h
+++ b/src/nvim/indent.h
@@ -1,6 +1,5 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 #include "nvim/pos_defs.h"  // IWYU pragma: keep
 #include "nvim/types_defs.h"  // IWYU pragma: keep
diff --git a/src/nvim/indent_c.h b/src/nvim/indent_c.h
index 64ba67a42b..65a402f02c 100644
--- a/src/nvim/indent_c.h
+++ b/src/nvim/indent_c.h
@@ -1,7 +1,7 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/pos_defs.h"  // IWYU pragma: keep
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "indent_c.h.generated.h"
diff --git a/src/nvim/memfile.h b/src/nvim/memfile.h
index 687ac042a4..6e7b575e5b 100644
--- a/src/nvim/memfile.h
+++ b/src/nvim/memfile.h
@@ -1,7 +1,7 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/memfile_defs.h"  // IWYU pragma: export
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 
 /// flags for mf_sync()
 enum {
diff --git a/src/nvim/memline.c b/src/nvim/memline.c
index 25c2de89e0..63f3541b3c 100644
--- a/src/nvim/memline.c
+++ b/src/nvim/memline.c
@@ -48,7 +48,6 @@
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
 #include "nvim/buffer.h"
-#include "nvim/buffer_defs.h"
 #include "nvim/change.h"
 #include "nvim/cursor.h"
 #include "nvim/drawscreen.h"
diff --git a/src/nvim/memline.h b/src/nvim/memline.h
index e70a8e423e..808d97783e 100644
--- a/src/nvim/memline.h
+++ b/src/nvim/memline.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
 #include "nvim/memline_defs.h"  // IWYU pragma: export
 #include "nvim/pos_defs.h"  // IWYU pragma: keep
 #include "nvim/types_defs.h"  // IWYU pragma: keep
diff --git a/src/nvim/memory.h b/src/nvim/memory.h
index d425249ab6..1511876c81 100644
--- a/src/nvim/memory.h
+++ b/src/nvim/memory.h
@@ -2,7 +2,7 @@
 
 #include <stdbool.h>
 #include <stdint.h>  // IWYU pragma: keep
-#include <string.h>
+#include <string.h>  // IWYU pragma: keep
 #include <time.h>  // IWYU pragma: keep
 
 #include "auto/config.h"
diff --git a/src/nvim/mouse.c b/src/nvim/mouse.c
index 35db717058..a026859a7e 100644
--- a/src/nvim/mouse.c
+++ b/src/nvim/mouse.c
@@ -6,7 +6,6 @@
 
 #include "nvim/ascii_defs.h"
 #include "nvim/buffer.h"
-#include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/cursor.h"
 #include "nvim/drawscreen.h"
diff --git a/src/nvim/mouse.h b/src/nvim/mouse.h
index d787b8ff57..2dcb3469da 100644
--- a/src/nvim/mouse.h
+++ b/src/nvim/mouse.h
@@ -1,6 +1,5 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
 #include "nvim/normal_defs.h"  // IWYU pragma: keep
 #include "nvim/types_defs.h"  // IWYU pragma: keep
diff --git a/src/nvim/move.h b/src/nvim/move.h
index f48de6987b..afeaeba235 100644
--- a/src/nvim/move.h
+++ b/src/nvim/move.h
@@ -1,6 +1,5 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
 #include "nvim/types_defs.h"  // IWYU pragma: keep
 #include "nvim/vim_defs.h"  // IWYU pragma: keep
diff --git a/src/nvim/normal.c b/src/nvim/normal.c
index dbcec0721f..3937533d36 100644
--- a/src/nvim/normal.c
+++ b/src/nvim/normal.c
@@ -18,7 +18,6 @@
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
 #include "nvim/buffer.h"
-#include "nvim/buffer_defs.h"
 #include "nvim/change.h"
 #include "nvim/charset.h"
 #include "nvim/cmdhist.h"
diff --git a/src/nvim/normal.h b/src/nvim/normal.h
index dbe74712fc..93e3e09c2e 100644
--- a/src/nvim/normal.h
+++ b/src/nvim/normal.h
@@ -1,9 +1,11 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include <stddef.h>  // IWYU pragma: keep
+
 #include "nvim/macros_defs.h"
 #include "nvim/normal_defs.h"  // IWYU pragma: export
 #include "nvim/pos_defs.h"  // IWYU pragma: keep
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 
 /// Values for find_ident_under_cursor()
 enum {
diff --git a/src/nvim/option.c b/src/nvim/option.c
index b1bc34744c..49a8c468d6 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -38,6 +38,7 @@
 #include "nvim/cmdexpand.h"
 #include "nvim/cmdexpand_defs.h"
 #include "nvim/cursor_shape.h"
+#include "nvim/decoration_defs.h"
 #include "nvim/decoration_provider.h"
 #include "nvim/diff.h"
 #include "nvim/drawscreen.h"
diff --git a/src/nvim/optionstr.h b/src/nvim/optionstr.h
index b317e55b7e..ae35d706aa 100644
--- a/src/nvim/optionstr.h
+++ b/src/nvim/optionstr.h
@@ -2,9 +2,9 @@
 
 #include <stdint.h>  // IWYU pragma: keep
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/cmdexpand_defs.h"  // IWYU pragma: keep
 #include "nvim/option_defs.h"  // IWYU pragma: keep
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "optionstr.h.generated.h"
diff --git a/src/nvim/os/os.h b/src/nvim/os/os.h
index 302d84d066..7ba5f05448 100644
--- a/src/nvim/os/os.h
+++ b/src/nvim/os/os.h
@@ -4,11 +4,11 @@
 #include <stdint.h>  // IWYU pragma: keep
 #include <uv.h>  // IWYU pragma: keep
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/cmdexpand_defs.h"  // IWYU pragma: keep
 #include "nvim/garray_defs.h"  // IWYU pragma: keep
 #include "nvim/os/os_defs.h"  // IWYU pragma: export
 #include "nvim/os/stdpaths_defs.h"  // IWYU pragma: keep
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 
 #define HAVE_PATHDEF
 
diff --git a/src/nvim/os/os_win_console.c b/src/nvim/os/os_win_console.c
index 816e81e997..953d291290 100644
--- a/src/nvim/os/os_win_console.c
+++ b/src/nvim/os/os_win_console.c
@@ -1,6 +1,7 @@
 #include <string.h>
 
 #include "nvim/globals.h"
+#include "nvim/memory.h"
 #include "nvim/os/fs.h"
 #include "nvim/os/input.h"
 #include "nvim/os/os.h"
@@ -105,3 +106,40 @@ void os_title_reset(void)
 {
   SetConsoleTitle(origTitle);
 }
+
+#if !defined(ENABLE_VIRTUAL_TERMINAL_PROCESSING)
+# define ENABLE_VIRTUAL_TERMINAL_PROCESSING 0x0004
+#endif
+/// Guesses the terminal-type.  Calls SetConsoleMode() and uv_set_vterm_state()
+/// if appropriate.
+///
+/// @param[in,out] term Name of the guessed terminal, statically-allocated
+/// @param out_fd stdout file descriptor
+void os_tty_guess_term(const char **term, int out_fd)
+{
+  bool conemu_ansi = strequal(os_getenv("ConEmuANSI"), "ON");
+  bool vtp = false;
+
+  HANDLE handle = (HANDLE)_get_osfhandle(out_fd);
+  DWORD dwMode;
+  if (handle != INVALID_HANDLE_VALUE && GetConsoleMode(handle, &dwMode)) {
+    dwMode |= ENABLE_VIRTUAL_TERMINAL_PROCESSING;
+    if (SetConsoleMode(handle, dwMode)) {
+      vtp = true;
+    }
+  }
+
+  if (*term == NULL) {
+    if (vtp) {
+      *term = "vtpcon";
+    } else if (conemu_ansi) {
+      *term = "conemu";
+    } else {
+      *term = "win32con";
+    }
+  }
+
+  if (conemu_ansi) {
+    uv_tty_set_vterm_state(UV_TTY_SUPPORTED);
+  }
+}
diff --git a/src/nvim/os/pty_conpty_win.c b/src/nvim/os/pty_conpty_win.c
index 53169c0ef8..e7697880af 100644
--- a/src/nvim/os/pty_conpty_win.c
+++ b/src/nvim/os/pty_conpty_win.c
@@ -1,5 +1,6 @@
 #include <uv.h>
 
+#include "nvim/log.h"
 #include "nvim/os/os.h"
 #include "nvim/os/pty_conpty_win.h"
 #include "nvim/vim_defs.h"
diff --git a/src/nvim/os/pty_process_win.c b/src/nvim/os/pty_process_win.c
index ca2dce36ea..563a79358c 100644
--- a/src/nvim/os/pty_process_win.c
+++ b/src/nvim/os/pty_process_win.c
@@ -4,6 +4,7 @@
 
 #include "nvim/ascii_defs.h"
 #include "nvim/eval/typval.h"
+#include "nvim/log.h"
 #include "nvim/mbyte.h"
 #include "nvim/memory.h"
 #include "nvim/os/os.h"
diff --git a/src/nvim/os/tty.c b/src/nvim/os/tty.c
deleted file mode 100644
index 57325c312f..0000000000
--- a/src/nvim/os/tty.c
+++ /dev/null
@@ -1,52 +0,0 @@
-//
-// Terminal/console utils
-//
-
-#ifdef MSWIN
-# include "nvim/memory.h"
-# include "nvim/os/os.h"
-#endif
-#include "nvim/os/tty.h"
-
-#ifdef INCLUDE_GENERATED_DECLARATIONS
-# include "os/tty.c.generated.h"  // IWYU pragma: export
-#endif
-
-#ifdef MSWIN
-# if !defined(ENABLE_VIRTUAL_TERMINAL_PROCESSING)
-#  define ENABLE_VIRTUAL_TERMINAL_PROCESSING 0x0004
-# endif
-/// Guesses the terminal-type.  Calls SetConsoleMode() and uv_set_vterm_state()
-/// if appropriate.
-///
-/// @param[in,out] term Name of the guessed terminal, statically-allocated
-/// @param out_fd stdout file descriptor
-void os_tty_guess_term(const char **term, int out_fd)
-{
-  bool conemu_ansi = strequal(os_getenv("ConEmuANSI"), "ON");
-  bool vtp = false;
-
-  HANDLE handle = (HANDLE)_get_osfhandle(out_fd);
-  DWORD dwMode;
-  if (handle != INVALID_HANDLE_VALUE && GetConsoleMode(handle, &dwMode)) {
-    dwMode |= ENABLE_VIRTUAL_TERMINAL_PROCESSING;
-    if (SetConsoleMode(handle, dwMode)) {
-      vtp = true;
-    }
-  }
-
-  if (*term == NULL) {
-    if (vtp) {
-      *term = "vtpcon";
-    } else if (conemu_ansi) {
-      *term = "conemu";
-    } else {
-      *term = "win32con";
-    }
-  }
-
-  if (conemu_ansi) {
-    uv_tty_set_vterm_state(UV_TTY_SUPPORTED);
-  }
-}
-#endif
diff --git a/src/nvim/os/tty.h b/src/nvim/os/tty.h
deleted file mode 100644
index 3a78573189..0000000000
--- a/src/nvim/os/tty.h
+++ /dev/null
@@ -1,5 +0,0 @@
-#pragma once
-
-#ifdef INCLUDE_GENERATED_DECLARATIONS
-# include "os/tty.h.generated.h"
-#endif
diff --git a/src/nvim/popupmenu.c b/src/nvim/popupmenu.c
index 386c13f630..df82cb259e 100644
--- a/src/nvim/popupmenu.c
+++ b/src/nvim/popupmenu.c
@@ -12,7 +12,6 @@
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
 #include "nvim/buffer.h"
-#include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/drawscreen.h"
 #include "nvim/eval/typval.h"
diff --git a/src/nvim/popupmenu.h b/src/nvim/popupmenu.h
index 1e4a1584ea..20a342b841 100644
--- a/src/nvim/popupmenu.h
+++ b/src/nvim/popupmenu.h
@@ -2,11 +2,11 @@
 
 #include <stdbool.h>
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
 #include "nvim/grid_defs.h"
 #include "nvim/macros_defs.h"
 #include "nvim/menu_defs.h"  // IWYU pragma: keep
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 
 /// Used for popup menu items.
 typedef struct {
diff --git a/src/nvim/regexp.h b/src/nvim/regexp.h
index 447f4860a9..1414749c2f 100644
--- a/src/nvim/regexp.h
+++ b/src/nvim/regexp.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
 #include "nvim/pos_defs.h"  // IWYU pragma: keep
 #include "nvim/regexp_defs.h"  // IWYU pragma: export
 #include "nvim/types_defs.h"  // IWYU pragma: keep
diff --git a/src/nvim/search.c b/src/nvim/search.c
index a23d27635f..8279b4857c 100644
--- a/src/nvim/search.c
+++ b/src/nvim/search.c
@@ -11,7 +11,6 @@
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
 #include "nvim/buffer.h"
-#include "nvim/buffer_defs.h"
 #include "nvim/change.h"
 #include "nvim/charset.h"
 #include "nvim/cmdhist.h"
diff --git a/src/nvim/search.h b/src/nvim/search.h
index 12553c8e74..04a06f75a2 100644
--- a/src/nvim/search.h
+++ b/src/nvim/search.h
@@ -3,7 +3,6 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/eval/typval_defs.h"
 #include "nvim/normal_defs.h"  // IWYU pragma: keep
 #include "nvim/os/time_defs.h"
diff --git a/src/nvim/sign.c b/src/nvim/sign.c
index 2bf328bf75..b52142f721 100644
--- a/src/nvim/sign.c
+++ b/src/nvim/sign.c
@@ -13,7 +13,6 @@
 #include "nvim/api/private/helpers.h"
 #include "nvim/ascii_defs.h"
 #include "nvim/buffer.h"
-#include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/cmdexpand_defs.h"
 #include "nvim/cursor.h"
diff --git a/src/nvim/sign.h b/src/nvim/sign.h
index 1c607bc7de..2b6497c255 100644
--- a/src/nvim/sign.h
+++ b/src/nvim/sign.h
@@ -1,6 +1,5 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/cmdexpand_defs.h"  // IWYU pragma: keep
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 #include "nvim/sign_defs.h"  // IWYU pragma: export
diff --git a/src/nvim/statusline.c b/src/nvim/statusline.c
index d31b8ef0b1..01729bc4de 100644
--- a/src/nvim/statusline.c
+++ b/src/nvim/statusline.c
@@ -10,7 +10,6 @@
 #include "nvim/api/private/helpers.h"
 #include "nvim/ascii_defs.h"
 #include "nvim/buffer.h"
-#include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/digraph.h"
 #include "nvim/drawline.h"
diff --git a/src/nvim/statusline.h b/src/nvim/statusline.h
index e1038ef2ca..36fc5be68e 100644
--- a/src/nvim/statusline.h
+++ b/src/nvim/statusline.h
@@ -2,10 +2,10 @@
 
 #include <stddef.h>
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/macros_defs.h"
 #include "nvim/option_defs.h"  // IWYU pragma: keep
 #include "nvim/statusline_defs.h"  // IWYU pragma: export
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 
 /// Array defining what should be done when tabline is clicked
 EXTERN StlClickDefinition *tab_page_click_defs INIT( = NULL);
diff --git a/src/nvim/syntax.c b/src/nvim/syntax.c
index d5ee93914a..41c9703f3b 100644
--- a/src/nvim/syntax.c
+++ b/src/nvim/syntax.c
@@ -10,7 +10,6 @@
 #include "nvim/ascii_defs.h"
 #include "nvim/autocmd.h"
 #include "nvim/buffer.h"
-#include "nvim/buffer_defs.h"
 #include "nvim/charset.h"
 #include "nvim/cmdexpand_defs.h"
 #include "nvim/drawscreen.h"
diff --git a/src/nvim/syntax.h b/src/nvim/syntax.h
index b9065acf7d..f07ad238d3 100644
--- a/src/nvim/syntax.h
+++ b/src/nvim/syntax.h
@@ -1,10 +1,10 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/cmdexpand_defs.h"  // IWYU pragma: keep
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 #include "nvim/macros_defs.h"
 #include "nvim/syntax_defs.h"  // IWYU pragma: export
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 
 enum {
   HL_CONTAINED   = 0x01,     ///< not used on toplevel
diff --git a/src/nvim/tag.h b/src/nvim/tag.h
index 87e71c8bef..42196b44b7 100644
--- a/src/nvim/tag.h
+++ b/src/nvim/tag.h
@@ -1,9 +1,9 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
 #include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 #include "nvim/option_defs.h"  // IWYU pragma: keep
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 
 enum { LSIZE = 512, };  ///< max. size of a line in the tags file
 
diff --git a/src/nvim/terminal.h b/src/nvim/terminal.h
index 1bbc1abd4a..317003c0d2 100644
--- a/src/nvim/terminal.h
+++ b/src/nvim/terminal.h
@@ -5,6 +5,7 @@
 #include <stdint.h>
 
 #include "nvim/api/private/defs.h"  // IWYU pragma: keep
+#include "nvim/types_defs.h"  // IWYU pragma: keep
 
 typedef void (*terminal_write_cb)(const char *buffer, size_t size, void *data);
 typedef void (*terminal_resize_cb)(uint16_t width, uint16_t height, void *data);
diff --git a/src/nvim/tui/tui.c b/src/nvim/tui/tui.c
index ba4069ecf4..6c0b00f010 100644
--- a/src/nvim/tui/tui.c
+++ b/src/nvim/tui/tui.c
@@ -40,7 +40,6 @@
 
 #ifdef MSWIN
 # include "nvim/os/os_win_console.h"
-# include "nvim/os/tty.h"
 #endif
 
 #define OUTBUF_SIZE 0xffff
diff --git a/src/nvim/undo.h b/src/nvim/undo.h
index f3a8a60d45..a70b1fe486 100644
--- a/src/nvim/undo.h
+++ b/src/nvim/undo.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "nvim/buffer_defs.h"  // IWYU pragma: keep
+#include "nvim/eval/typval_defs.h"  // IWYU pragma: keep
 #include "nvim/ex_cmds_defs.h"  // IWYU pragma: keep
 #include "nvim/pos_defs.h"  // IWYU pragma: keep
 #include "nvim/types_defs.h"  // IWYU pragma: keep