Add magical feature codegen system, at long last

34 files changed, 664 insertions, 376 deletions

diff --git a/TODO/.featgen b/TODO/.featgen
new file mode 100644
index 0000000..bf6dc38
--- /dev/null
+++ b/TODO/.featgen
@@ -0,0 +1,3 @@
+Feature setup code generation
+====
+It's done! See feature.h, event.h and the various stuff in codegen.c.
diff --git a/TODO/featgen b/TODO/featgen
deleted file mode 100644
index b71f32a..0000000
--- a/TODO/featgen
+++ /dev/null
@@ -1,9 +0,0 @@
-Feature setup code generation
-====
-Once the plugin has enough features across enough C files, setting up and
-tearing down everything will get kind of annoying. That's where some more code
-generation might be nice.
-
-There's a few vague ideas of how to do this but really it's pretty open-ended
-overall. In the meantime, we're just calling functions manually. Not a huge
-deal, really.
diff --git a/src/ac.c b/src/ac.c
index 2a1a8a4..4d21a48 100644
--- a/src/ac.c
+++ b/src/ac.c
@@ -23,14 +23,23 @@
 #include "hook.h"
 #include "engineapi.h"
 #include "errmsg.h"
+#include "event.h"
+#include "feature.h"
 #include "intdefs.h"
 #include "mem.h"
 #include "os.h"
 #include "ppmagic.h"
+#include "sst.h"
 #include "vcall.h"
 #include "x86.h"
 #include "x86util.h"
 
+FEATURE()
+REQUIRE(bind)
+REQUIRE(democustom)
+REQUIRE_GAMEDATA(vtidx_GetDesktopResolution)
+REQUIRE_GAMEDATA(vtidx_DispatchAllStoredGameMessages)
+
 static bool lockdown = false;
 
 #ifdef _WIN32
@@ -62,18 +71,10 @@ static ssize __stdcall mproc(int code, UINT_PTR wp, ssize lp) {
 static ulong __stdcall inhookthrmain(void *unused) {
 	if (!SetWindowsHookExW(WH_KEYBOARD_LL, &kproc, 0, 0) ||
 			!SetWindowsHookExW(WH_MOUSE_LL, &mproc, 0, 0)) {
-		// intentionally vague message
-		con_warn("sst: RTA mode is unavailable due to an error\n");
 		return -1;
 	}
 	MSG m; int ret;
 	while ((ret = GetMessageW(&m, inhookwin, 0, 0)) > 0) DispatchMessage(&m);
-	if (ret == -1) {
-		// XXX: if this ever happens, it's a disaster! users might not notice
-		// their run just dying all of a sudden. with any luck it won't matter
-		// in practice but... this kind of sucks.
-		con_warn("** sst: ERROR in message loop, abandoning RTA mode! **");
-	}
 	return ret;
 }
 
@@ -92,12 +93,15 @@ static void inhook_start(void) {
 	inhookthr = CreateThread(0, 0, &inhookthrmain, 0, 0, &inhooktid);
 }
 
-// TODO(rta): run this check every tick (or at least X amount of time)
 static void inhook_check(void) {
 	if (WaitForSingleObject(inhookthr, 0) == WAIT_OBJECT_0) {
 		ulong status;
 		GetExitCodeThread(inhookthr, &status);
-		if (status != 0) {
+		if (status) {
+			// XXX: if this ever happens, it's a disaster! users might not
+			// notice their run just dying all of a sudden. with any luck it
+			// won't matter in practice but... this kind of sucks.
+			con_warn("** sst: ERROR in message loop, abandoning RTA mode! **");
 			// TODO(rta): stop demos, and stuff.
 			lockdown = false;
 		}
@@ -110,6 +114,13 @@ static void inhook_stop(void) {
 		errmsg_warnsys("couldn't wait for thread, status unknown");
 		// XXX: now what!?
 	}
+	// assume WAIT_OBJECT_0
+	ulong status;
+	GetExitCodeThread(inhookthr, &status);
+	if (status) {
+		// not much else we can do now!
+		con_warn("warning: RTA mode message loop had an error during shutdown");
+	}
 }
 
 #else
@@ -131,6 +142,14 @@ static void startlockdown(void) {
 	// TODO(rta): start demos, etc
 }
 
+HANDLE_EVENT(Tick) {
+#ifdef _WIN32
+	static int fewticks = 0;
+	// just check this every so often (roughly 0.1-0.3s depending on game)
+	if (lockdown && !(++fewticks & 7)) inhook_check();
+#endif
+}
+
 static void endlockdown(void) {
 	if (!lockdown) return;
 #ifdef _WIN32
@@ -227,12 +246,7 @@ ok:	DispatchAllStoredGameMessages_func DispatchAllStoredGameMessages =
 	return false;
 }
 
-bool ac_init(void) {
-	if (!has_vtidx_GetDesktopResolution ||
-			!has_vtidx_DispatchAllStoredGameMessages) {
-		errmsg_errorx("missing gamedata entries for this engine");
-		return false;
-	}
+INIT {
 #if defined(_WIN32)
 	if (!win32_init()) return false;
 #elif defined(__linux__)
@@ -248,7 +262,7 @@ bool ac_init(void) {
 	return true;
 }
 
-void ac_end(void) {
+END {
 	endlockdown();
 	unhook_inline((void *)orig_DispatchInputEvent);
 }
diff --git a/src/ac.h b/src/ac.h
index 638b01f..7b48cd1 100644
--- a/src/ac.h
+++ b/src/ac.h
@@ -17,10 +17,7 @@
 #ifndef INC_AC_H
 #define INC_AC_H
 
-#include <stdbool.h>
-
-bool ac_init(void);
-void ac_end(void);
+// TODO(rta): keeping this header here as I expect to expose some functions...
 
 #endif
 
diff --git a/src/alias.c b/src/alias.c
index 3605800..b94a6d5 100644
--- a/src/alias.c
+++ b/src/alias.c
@@ -19,16 +19,27 @@
 
 #include "alias.h"
 #include "con_.h"
-#include "dbg.h"
 #include "errmsg.h"
 #include "extmalloc.h"
+#include "feature.h"
 #include "gametype.h"
 #include "mem.h"
 #include "x86.h"
 #include "x86util.h"
 
+FEATURE("alias management")
+
 struct alias **_alias_head;
 
+void alias_nuke(void) {
+	for (struct alias *p = alias_head; p;) {
+		struct alias *next = p->next;
+		extfree(p->value); extfree(p);
+		p = next;
+	}
+	alias_head = 0;
+}
+
 void alias_rm(const char *name) {
 	for (struct alias **p = _alias_head; *p; p = &(*p)->next) {
 		if (!strcmp((*p)->name, name)) {
@@ -40,7 +51,15 @@ void alias_rm(const char *name) {
 	}
 }
 
-DEF_CCMD_HERE(sst_alias_remove, "Remove a command alias", 0) {
+DEF_CCMD_HERE_UNREG(sst_alias_clear, "Remove all command aliases", 0) {
+	if (cmd->argc != 1) {
+		con_warn("usage: sst_alias_clear");
+		return;
+	}
+	alias_nuke();
+}
+
+DEF_CCMD_HERE_UNREG(sst_alias_remove, "Remove a command alias", 0) {
 	if (cmd->argc != 2) {
 		con_warn("usage: sst_alias_remove name");
 		return;
@@ -52,23 +71,6 @@ DEF_CCMD_HERE(sst_alias_remove, "Remove a command alias", 0) {
 	alias_rm(cmd->argv[1]);
 }
 
-void alias_nuke(void) {
-	for (struct alias *p = alias_head; p;) {
-		struct alias *next = p->next;
-		extfree(p->value); extfree(p);
-		p = next;
-	}
-	alias_head = 0;
-}
-
-DEF_CCMD_HERE(sst_alias_clear, "Remove all command aliases", 0) {
-	if (cmd->argc != 1) {
-		con_warn("usage: sst_alias_clear");
-		return;
-	}
-	alias_nuke();
-}
-
 static bool find_alias_head(con_cmdcb alias_cb) {
 #ifdef _WIN32
 	for (uchar *p = (uchar *)alias_cb; p - (uchar *)alias_cb < 64;) {
@@ -88,7 +90,7 @@ static bool find_alias_head(con_cmdcb alias_cb) {
 	return false;
 }
 
-bool alias_init(void) {
+INIT {
 	// TODO(compat): no idea why sst_alias_clear crashes in p2, figure out later
 	if (GAMETYPE_MATCHES(Portal2)) return false;
 
@@ -101,6 +103,8 @@ bool alias_init(void) {
 		errmsg_warnx("couldn't find alias list");
 		return false;
 	};
+	con_reg(sst_alias_clear);
+	con_reg(sst_alias_remove);
 	return true;
 }
 
diff --git a/src/alias.h b/src/alias.h
index 3e417d9..bc125eb 100644
--- a/src/alias.h
+++ b/src/alias.h
@@ -17,8 +17,6 @@
 #ifndef INC_ALIAS_H
 #define INC_ALIAS_H
 
-#include <stdbool.h>
-
 struct alias {
 	struct alias *next;
 	char name[32]; // TIL this has a hard limit :^)
@@ -27,10 +25,8 @@ struct alias {
 extern struct alias **_alias_head;
 #define alias_head (*_alias_head) // act as a global
 
-void alias_rm(const char *name);
 void alias_nuke(void);
-
-bool alias_init(void);
+void alias_rm(const char *name);
 
 #endif
 
diff --git a/src/autojump.c b/src/autojump.c
index 284dd85..c4f54f4 100644
--- a/src/autojump.c
+++ b/src/autojump.c
@@ -19,6 +19,7 @@
 #include "con_.h"
 #include "engineapi.h"
 #include "errmsg.h"
+#include "feature.h"
 #include "gamedata.h"
 #include "gametype.h"
 #include "intdefs.h"
@@ -27,6 +28,11 @@
 #include "os.h"
 #include "vcall.h"
 
+FEATURE("autojump")
+REQUIRE_GAMEDATA(off_mv)
+REQUIRE_GAMEDATA(vtidx_CheckJumpButton)
+REQUIRE_GLOBAL(factory_client) // note: server will never be null
+
 DEF_CVAR(sst_autojump, "Jump upon hitting the ground while holding space", 0,
 		CON_REPLICATE | CON_DEMO | CON_HIDDEN)
 
@@ -69,17 +75,7 @@ static bool unprot(void *gm) {
 	return ret;
 }
 
-bool autojump_init(void) {
-	// TODO(featgen): auto-check these factories
-	if (!factory_client || !factory_server) {
-		errmsg_errorx("missing required factories");
-		return false;
-	}
-	if (!has_vtidx_CheckJumpButton || !has_off_mv) {
-		errmsg_errorx("missing gamedata entries for this engine");
-		return false;
-	}
-
+INIT {
 	gmsv = factory_server("GameMovement001", 0);
 	if (!gmsv) {
 		errmsg_errorx("couldn't get server-side game movement interface");
@@ -111,7 +107,7 @@ bool autojump_init(void) {
 	return true;
 }
 
-void autojump_end(void) {
+END {
 	unhook_vtable(*(void ***)gmsv, vtidx_CheckJumpButton, (void *)origsv);
 	unhook_vtable(*(void ***)gmcl, vtidx_CheckJumpButton, (void *)origcl);
 }
diff --git a/src/autojump.h b/src/autojump.h
deleted file mode 100644
index 56377b7..0000000
--- a/src/autojump.h
+++ /dev/null
@@ -1,27 +0,0 @@
-/*
- * Copyright © 2021 Michael Smith <mikesmiffy128@gmail.com>
- *
- * Permission to use, copy, modify, and/or distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
- * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
- * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
- * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
- * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
- * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
- * PERFORMANCE OF THIS SOFTWARE.
- */
-
-#ifndef INC_AUTOJUMP_H
-#define INC_AUTOJUMP_H
-
-#include <stdbool.h>
-
-bool autojump_init(void);
-void autojump_end(void);
-
-#endif
-
-// vi: sw=4 ts=4 noet tw=80 cc=80
diff --git a/src/bind.c b/src/bind.c
index 62cdec3..762259d 100644
--- a/src/bind.c
+++ b/src/bind.c
@@ -19,12 +19,15 @@
 #include "con_.h"
 #include "dbg.h"
 #include "errmsg.h"
+#include "feature.h"
 #include "hook.h"
 #include "intdefs.h"
 #include "mem.h"
 #include "x86.h"
 #include "x86util.h"
 
+FEATURE()
+
 struct keyinfo {
 	char *binding;
 	uchar keyuptgt : 3;
@@ -53,7 +56,7 @@ static bool find_keyinfo(con_cmdcb klbc_cb) {
 	return false;
 }
 
-bool bind_init(void) {
+INIT {
 	struct con_cmd *cmd_key_listboundkeys = con_findcmd("key_listboundkeys");
 	if (!cmd_key_listboundkeys) {
 		errmsg_errorx("couldn't find key_listboundkeys command");
diff --git a/src/bind.h b/src/bind.h
index 4d91a96..daf97da 100644
--- a/src/bind.h
+++ b/src/bind.h
@@ -17,12 +17,8 @@
 #ifndef INC_BIND_H
 #define INC_BIND_H
 
-#include <stdbool.h>
-
 const char *bind_get(int keycode);
 
-bool bind_init(void);
-
 #endif
 
 // vi: sw=4 ts=4 noet tw=80 cc=80
diff --git a/src/build/cmeta.c b/src/build/cmeta.c
index 3d49927..260d33f 100644
--- a/src/build/cmeta.c
+++ b/src/build/cmeta.c
@@ -20,6 +20,7 @@
 
 #include "../intdefs.h"
 #include "../os.h"
+#include "cmeta.h"
 
 /*
  * This file does C metadata parsing/scraping for the build system. This
@@ -31,10 +32,12 @@
  * time. Don't worry about it too much.
  */
 
-// too lazy to write a C tokenizer at the moment, so let's just yoink some code
-// from a hacked-up copy of chibicc, a nice minimal C compiler with code that's
-// pretty easy to work with. it does leak memory by design, but build stuff is
-// all one-shot so that's fine.
+// lazy inlined 3rd party stuff {{{
+// too lazy to write a C tokenizer at the moment, or indeed probably ever, so
+// let's just yoink some code from a hacked-up copy of chibicc, a nice minimal C
+// compiler with code that's pretty easy to work with. it does leak memory by
+// design, but build stuff is all one-shot so that's fine.
+#include "../3p/chibicc/chibicc.h"
 #include "../3p/chibicc/unicode.c"
 // type sentinels from type.c (don't bring in the rest of type.c because it
 // circularly depends on other stuff and we really only want tokenize here)
@@ -88,6 +91,7 @@ static char *join_tokens(Token *tok, Token *end) {
   buf[pos] = '\0';
   return buf;
 }
+// }}}
 
 #ifdef _WIN32
 #include "../3p/openbsd/asprintf.c" // missing from libc; plonked here for now
@@ -266,7 +270,74 @@ void cmeta_conmacros(const struct cmeta *cm,
 	}
 }
 
-void cmeta_evdefmacros(const struct cmeta *cm, void (*cb_def)(const char *name)) {
+const char *cmeta_findfeatmacro(const struct cmeta *cm) {
+	Token *tp = (Token *)cm;
+	if (!tp || !tp->next) return 0; // FEATURE, (
+	while (tp) {
+		if (equal(tp, "FEATURE") && equal(tp->next, "(")) {
+			if (equal(tp->next->next, ")")) return ""; // no arg = no desc
+			if (!tp->next->next || tp->next->next->kind != TK_STR) {
+				return 0; // it's invalid, whatever, just return...
+			}
+			return tp->next->next->str;
+		}
+		tp = tp->next;
+	}
+	return 0;
+}
+
+void cmeta_featinfomacros(const struct cmeta *cm, void (*cb)(
+		enum cmeta_featmacro type, const char *param, void *ctxt), void *ctxt) {
+	Token *tp = (Token *)cm;
+	if (!tp || !tp->next) return;
+	while (tp) {
+		int type = -1;
+		if (equal(tp, "PREINIT")) {
+			type = CMETA_FEAT_PREINIT;
+		}
+		else if (equal(tp, "INIT")) {
+			type = CMETA_FEAT_INIT;
+		}
+		else if (equal(tp, "END")) {
+			type = CMETA_FEAT_END;
+		}
+		if (type != - 1) {
+			if (equal(tp->next, "{")) {
+				cb(type, 0, ctxt);
+				tp = tp->next;
+			}
+			tp = tp->next;
+			continue;
+		}
+		if (equal(tp, "REQUIRE")) {
+			type = CMETA_FEAT_REQUIRE;
+		}
+		else if (equal(tp, "REQUIRE_GAMEDATA")) {
+			type = CMETA_FEAT_REQUIREGD;
+		}
+		else if (equal(tp, "REQUIRE_GLOBAL")) {
+			type = CMETA_FEAT_REQUIREGLOBAL;
+		}
+		else if (equal(tp, "REQUEST")) {
+			type = CMETA_FEAT_REQUEST;
+		}
+		if (type != -1) {
+			if (equal(tp->next, "(") && tp->next->next) {
+				tp = tp->next->next;
+				char *param = malloc(tp->len + 1);
+				if (!param) die1("couldn't allocate memory");
+				memcpy(param, tp->loc, tp->len);
+				param[tp->len] = '\0';
+				cb(type, param, ctxt);
+				tp = tp->next;
+			}
+		}
+		tp = tp->next;
+	}
+}
+
+void cmeta_evdefmacros(const struct cmeta *cm,
+		void (*cb_def)(const char *name)) {
 	Token *tp = (Token *)cm;
 	if (!tp || !tp->next || !tp->next->next) return; // DEF_EVENT, (, name
 	while (tp) {
@@ -298,4 +369,4 @@ void cmeta_evhandlermacros(const struct cmeta *cm, const char *modname,
 	}
 }
 
-// vi: sw=4 ts=4 noet tw=80 cc=80
+// vi: sw=4 ts=4 noet tw=80 cc=80 fdm=marker
diff --git a/src/build/cmeta.h b/src/build/cmeta.h
index 125ce2c..40c4ac5 100644
--- a/src/build/cmeta.h
+++ b/src/build/cmeta.h
@@ -40,6 +40,39 @@ void cmeta_conmacros(const struct cmeta *cm,
 		void (*cb)(const char *name, bool isvar, bool unreg));
 
 /*
+ * Looks for a feature description macro in file, returning the description
+ * string if it exists, an empty string if the feature is defined without a
+ * user-facing description, and null if source file does not define a feature.
+ */
+const char *cmeta_findfeatmacro(const struct cmeta *cm);
+
+/*
+ * the various kinds of feature specficiation macros, besides the feature
+ * declaration macro itself
+ */
+enum cmeta_featmacro {
+	CMETA_FEAT_REQUIRE,
+	CMETA_FEAT_REQUIREGD,
+	CMETA_FEAT_REQUIREGLOBAL,
+	CMETA_FEAT_REQUEST,
+	CMETA_FEAT_PREINIT,
+	CMETA_FEAT_INIT,
+	CMETA_FEAT_END
+};
+
+/*
+ * Iterates through all feature dependency macros and init/end/preinit
+ * indicators, passing each bit of information to the callback cb.
+ *
+ * PREINT, INIT and END macros don't pass anything to param.
+ *
+ * This one takes a context pointer, while the others don't, because this is all
+ * cobbled together without much consistent abstraction.
+ */
+void cmeta_featinfomacros(const struct cmeta *cm, void (*cb)(
+		enum cmeta_featmacro type, const char *param, void *ctxt), void *ctxt);
+
+/*
  * Iterates through all event-related macros and takes note of which events are
  * defined, giving a callback for each.
  */
diff --git a/src/build/codegen.c b/src/build/codegen.c
index 1dee6a1..04a9058 100644
--- a/src/build/codegen.c
+++ b/src/build/codegen.c
@@ -14,35 +14,37 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
+#include "../intdefs.h"
 #include "../os.h"
 #include "cmeta.h"
 #include "skiplist.h"
 #include "vec.h"
 
-#define MAXENT 65536 // arbitrary limit!
-static struct ent {
-	const char *name;
-	bool unreg;
-	bool isvar; // false for cmd
-} ents[MAXENT];
-static int nents;
-
 static void die(const char *s) {
 	fprintf(stderr, "codegen: %s\n", s);
 	exit(100);
 }
 
+#define MAXENT 65536 // arbitrary limit!
+static struct conent {
+	const char *name;
+	bool unreg;
+	bool isvar; // false for cmd
+} conents[MAXENT];
+static int nconents;
+
 #define PUT(name_, isvar_, unreg_) do { \
-	if (nents == sizeof(ents) / sizeof(*ents)) { \
+	if (nconents == sizeof(conents) / sizeof(*conents)) { \
 		fprintf(stderr, "codegen: out of space; make ents bigger!\n"); \
 		exit(1); \
 	} \
-	ents[nents].name = name_; \
-	ents[nents].isvar = isvar_; ents[nents++].unreg = unreg_; \
+	conents[nconents].name = name_; \
+	conents[nconents].isvar = isvar_; conents[nconents++].unreg = unreg_; \
 } while (0)
 
 static void oncondef(const char *name, bool isvar, bool unreg) {
@@ -50,10 +52,95 @@ static void oncondef(const char *name, bool isvar, bool unreg) {
 }
 
 struct vec_str VEC(const char *);
+struct vec_usize VEC(usize);
+struct vec_featp VEC(struct feature *);
+
+enum { UNSEEN, SEEING, SEEN };
+
+DECL_SKIPLIST(static, feature, struct feature, const char *, 4)
+DECL_SKIPLIST(static, feature_bydesc, struct feature, const char *, 4)
+struct feature {
+	const char *modname;
+	const char *desc;
+	const struct cmeta *cm; // backref for subsequent options pass
+	struct vec_featp needs;
+	// keep optionals in a separate array mainly so we have separate counts
+	struct vec_featp wants;
+	uint dfsstate : 2; // used for sorting and cycle checking
+	bool has_preinit : 1, /*has_init : 1, <- required anyway! */ has_end : 1;
+	bool has_evhandlers : 1;
+	bool is_requested : 1; // determines if has_ variable needs to be extern
+	//char pad : 2;
+	//char pad[3];
+	struct vec_str need_gamedata;
+	struct vec_str need_globals;
+	struct skiplist_hdr_feature hdr; // by id/modname
+	struct skiplist_hdr_feature_bydesc hdr_bydesc;
+};
+static inline int cmp_feature(struct feature *e, const char *s) {
+	return strcmp(e->modname, s);
+}
+static inline int cmp_feature_bydesc(struct feature *e, const char *s) {
+	for (const char *p = e->desc; ; ++p, ++s) {
+		// longer string first
+		if (!*s) return !!*p; else if (!*p) return -1;
+		// case insensitive sort where possible
+		if (tolower(*p) > tolower(*s)) return 1;
+		if (tolower(*p) < tolower(*s)) return -1;
+		// prioritise upper-case if same letter
+		if (isupper(*p) && islower(*s)) return 1;
+		if (islower(*p) && isupper(*s)) return -1;
+	}
+	return 0;
+}
+static inline struct skiplist_hdr_feature *hdr_feature(struct feature *e) {
+	return &e->hdr;
+}
+static inline struct skiplist_hdr_feature_bydesc *hdr_feature_bydesc(
+		struct feature *e) {
+	return &e->hdr_bydesc;
+}
+DEF_SKIPLIST(static, feature, cmp_feature, hdr_feature)
+DEF_SKIPLIST(static, feature_bydesc, cmp_feature_bydesc, hdr_feature_bydesc)
+static struct skiplist_hdr_feature features = {0};
+// sort in two different ways, so we can alphabetise the user-facing display
+// NOTE: not all features will show up in this second list!
+static struct skiplist_hdr_feature_bydesc features_bydesc = {0};
+
+static void onfeatinfo(enum cmeta_featmacro type, const char *param,
+		void *ctxt) {
+	struct feature *f = ctxt;
+	switch (type) {
+		case CMETA_FEAT_REQUIRE:; bool optional = false; goto dep;
+		case CMETA_FEAT_REQUEST: optional = true;
+dep:		struct feature *dep = skiplist_get_feature(&features, param);
+			if (optional) dep->is_requested = true;
+			if (!dep) {
+				fprintf(stderr, "codegen: error: feature `%s` tried to depend "
+						"on non-existent feature `%s`\n", f->modname, param);
+				exit(1); \
+			}
+			if (!vec_push(optional ? &f->wants : &f->needs, dep)) {
+				die("couldn't allocate memory");
+			}
+			break;
+		case CMETA_FEAT_REQUIREGD:;
+			struct vec_str *vecp = &f->need_gamedata;
+			goto push;
+		case CMETA_FEAT_REQUIREGLOBAL:
+			vecp = &f->need_globals;
+push:		if (!vec_push(vecp, param)) die("couldn't allocate memory");
+			break;
+		case CMETA_FEAT_PREINIT: f->has_preinit = true; break;
+		case CMETA_FEAT_END: f->has_end = true; break;
+		case CMETA_FEAT_INIT:; // nop for now, I guess
+	}
+}
+
 DECL_SKIPLIST(static, event, struct event, const char *, 4)
-struct event {
+	struct event {
 	const char *name;
-	struct vec_str handlers;
+	struct vec_usize handlers; // strings, but with tagged pointers - see below
 	struct skiplist_hdr_event hdr;
 };
 static inline int cmp_event(struct event *e, const char *s) {
@@ -63,7 +150,7 @@ static inline struct skiplist_hdr_event *hdr_event(struct event *e) {
 	return &e->hdr;
 }
 DEF_SKIPLIST(static, event, cmp_event, hdr_event)
-struct skiplist_hdr_event events = {0};
+static struct skiplist_hdr_event events = {0};
 
 static void onevdef(const char *name) {
 	struct event *e = skiplist_get_event(&events, name);
@@ -71,7 +158,7 @@ static void onevdef(const char *name) {
 		struct event *e = malloc(sizeof(*e));
 		if (!e) die("couldn't allocate memory");
 		e->name = name;
-		e->handlers = (struct vec_str){0};
+		e->handlers = (struct vec_usize){0};
 		e->hdr = (struct skiplist_hdr_event){0};
 		skiplist_insert_event(&events, name, e);
 	}
@@ -89,24 +176,95 @@ static void onevhandler(const char *evname, const char *modname) {
 				"non-existent event `%s`\n", modname, evname);
 		exit(2);
 	}
+	usize taggedptr = (usize)modname;
+	struct feature *f = skiplist_get_feature(&features, modname);
+	// hack: using unused pointer bit to determine whether a handler is tied to
+	// a feature and thus conditional. relies on malloc alignment!
+	if (f) taggedptr |= 1ull;
 	// NOTE: not bothering to check for more than one handler in a file.
 	// compiler will get that anyway.
-	if (!vec_push(&e->handlers, modname)) die("couldn't allocate memory");
+	if (!vec_push(&e->handlers, taggedptr)) die("couldn't allocate memory");
 }
 
+struct passinfo {
+	const struct cmeta *cm;
+	const os_char *path;
+};
+static struct vec_passinfo VEC(struct passinfo) pass2 = {0};
+
 #define _(x) \
 	if (fprintf(out, "%s\n", x) < 0) die("couldn't write to file");
 #define F(f, ...) \
 	if (fprintf(out, f "\n", __VA_ARGS__) < 0) die("couldn't write to file");
-#define H() \
-_( "/* This file is autogenerated by src/build/codegen.c. DO NOT EDIT! */") \
-_( "")
+#define H_() \
+	_( "/* This file is autogenerated by "__FILE__". DO NOT EDIT! */")
+#define H() H_() _( "")
 
-struct passinfo {
-	const struct cmeta *cm;
-	const os_char *path;
-};
-struct vec_passinfo VEC(struct passinfo) pass2 = {0};
+static struct vec_featp endstack = {0}; // stack for reversing order
+
+static void featdfs(FILE *out, struct feature *f) {
+	if (f->dfsstate == SEEN) return;
+	if (f->dfsstate == SEEING) {
+		// XXX: could unwind for full cycle listing like in build.
+		// purely being lazy by not doing that here, and assuming there won't
+		// actually be cycles anyway, because this is not a general purpose tool
+		// and people working on this codebase are very smart.
+		fprintf(stderr, "codegen: error: dependency cycle found at feature `%s`\n",
+				f->modname);
+		exit(2);
+	}
+	f->dfsstate = SEEING;
+	// easier to do wants first, then we can do the conditional counter nonsense
+	// without worrying about how that fits in...
+	for (struct feature *const *pp = f->wants.data;
+			pp - f->wants.data < f->wants.sz; ++pp) {
+		featdfs(out, *pp);
+	}
+F( "	char status_%s = FEAT_OK;", f->modname);
+	const char *else_ = "";
+	if (f->needs.sz == 1) {
+		featdfs(out, f->needs.data[0]);
+F( "	if (status_%s != FEAT_OK) status_%s = FEAT_REQFAIL;",
+		f->needs.data[0]->modname, f->modname)
+		else_ = "else ";
+	}
+	else if (f->needs.sz > 1) {
+		for (struct feature *const *pp = f->needs.data;
+				pp - f->needs.data < f->needs.sz; ++pp) {
+			featdfs(out, *pp);
+		}
+F( "	bool metdeps_%s =", f->modname)
+		for (struct feature *const *pp = f->needs.data;
+				pp - f->needs.data < f->needs.sz; ++pp) {
+F( "		status_%s == FEAT_OK%s", (*pp)->modname,
+		pp - f->needs.data == f->needs.sz - 1 ? ";" : " &&") // dumb but oh well
+		}
+F( "	if (!metdeps_%s) status_%s = FEAT_REQFAIL;", f->modname, f->modname)
+		else_ = "else ";
+	}
+	if (f->has_preinit) {
+F( "	%sif (!_feature_preinit_%s()) status_%s = FEAT_PREFAIL;", else_,
+		f->modname, f->modname);
+		else_ = "else ";
+	}
+	for (const char **pp = f->need_gamedata.data;
+			pp - f->need_gamedata.data < f->need_gamedata.sz; ++pp) {
+F( "	%sif (!has_%s) status_%s = FEAT_NOGD;", else_, *pp, f->modname)
+		else_ = "else "; // blegh
+	}
+	for (const char **pp = f->need_globals.data;
+			pp - f->need_globals.data < f->need_globals.sz; ++pp) {
+F( "	%sif (!%s) status_%s = FEAT_NOGLOBAL;", else_, *pp, f->modname)
+		else_ = "else "; // blegh 2
+	}
+F( "	%sif (!_feature_init_%s()) status_%s = FEAT_FAIL;", else_, f->modname,
+		f->modname)
+	if (f->has_end || f->has_evhandlers || f->is_requested) {
+F( "	has_%s = status_%s == FEAT_OK;", f->modname, f->modname)
+	}
+	if (!vec_push(&endstack, f)) die("couldn't allocate memory");
+	f->dfsstate = SEEN;
+}
 
 int OS_MAIN(int argc, os_char *argv[]) {
 	for (++argv; *argv; ++argv) {
@@ -118,8 +276,8 @@ int OS_MAIN(int argc, os_char *argv[]) {
 		}
 	}
 
-	// we have to a second pass for event handlers. also, there's a bunch of
-	// terrible garbage here. don't stare for too long...
+	// we have to do a second pass for features and event handlers. also,
+	// there's a bunch of terrible garbage here. don't stare for too long...
 	for (struct passinfo *pi = pass2.data; pi - pass2.data < pass2.sz; ++pi) {
 		// XXX: I guess we should cache these by name or something!
 		const struct cmeta *cm = pi->cm;
@@ -162,18 +320,36 @@ int OS_MAIN(int argc, os_char *argv[]) {
 		else if (!strcmp(modname, "sst")) {
 			continue; // I guess???
 		}
+		const char *featdesc = cmeta_findfeatmacro(cm);
+		if (featdesc) {
+			struct feature *f = malloc(sizeof(*f));
+			if (!f) die("couldn't allocate memory");
+			*f = (struct feature){
+				.modname = modname,
+				.desc = featdesc[0] ? featdesc : 0,
+				.cm = cm
+			};
+			skiplist_insert_feature(&features, modname, f);
+			if (f->desc) {
+				skiplist_insert_feature_bydesc(&features_bydesc, f->desc, f);
+			}
+		}
 		cmeta_evhandlermacros(cm, modname, &onevhandler);
 	}
+	// yet another pass because I am stupid and don't want to think harder :)
+	for (struct feature *f = features.x[0]; f; f = f->hdr.x[0]) {
+		cmeta_featinfomacros(f->cm, &onfeatinfo, f);
+	}
 
 	FILE *out = fopen(".build/include/cmdinit.gen.h", "wb");
 	if (!out) die("couldn't open cmdinit.gen.h");
-	H();
-	for (const struct ent *p = ents; p - ents < nents; ++p) {
+H();
+	for (const struct conent *p = conents; p - conents < nconents; ++p) {
 F( "extern struct con_%s *%s;", p->isvar ? "var" : "cmd", p->name)
 	}
 _( "")
 _( "static void regcmds(void) {")
-	for (const struct ent *p = ents; p - ents < nents; ++p) {
+	for (const struct conent *p = conents; p - conents < nconents; ++p) {
 		if (p->isvar) {
 F( "	initval(%s);", p->name)
 		}
@@ -184,23 +360,103 @@ F( "	con_reg(%s);", p->name)
 _( "}")
 _( "")
 _( "static void freevars(void) {")
-	for (const struct ent *p = ents; p - ents < nents; ++p) {
+	for (const struct conent *p = conents; p - conents < nconents; ++p) {
 		if (p->isvar) {
-F( "	extfree(%s->strval);", p->name);
+F( "	extfree(%s->strval);", p->name)
 		}
 	}
 _( "}")
 	if (fclose(out) == EOF) die("couldn't fully write cmdinit.gen.h");
 
+	out = fopen(".build/include/featureinit.gen.h", "wb");
+	if (!out) die("couldn't open featureinit.gen.h");
+	H()
+	// XXX: I dunno whether this should just be defined in sst.c. It's sort of
+	// internal to the generated stuff hence tucking it away here, but that's at
+	// the cost of extra string-spaghettiness
+_( "enum {")
+_( "	FEAT_OK,")
+_( "	FEAT_REQFAIL,")
+_( "	FEAT_PREFAIL,")
+_( "	FEAT_NOGD,")
+_( "	FEAT_NOGLOBAL,")
+_( "	FEAT_FAIL")
+_( "};")
+_( "")
+_( "static const char *const featmsgs[] = {")
+_( "	\" [     OK!     ] %s\\n\",")
+_( "	\" [   skipped   ] %s (requires another feature)\\n\",")
+_( "	\" [   skipped   ] %s (not applicable or useful)\\n\",")
+_( "	\" [ unsupported ] %s (missing gamedata)\\n\",")
+_( "	\" [   FAILED!   ] %s (failed to access engine)\\n\",")
+_( "	\" [   FAILED!   ] %s (error in initialisation)\\n\"")
+_( "};")
+_( "")
+	for (struct feature *f = features.x[0]; f; f = f->hdr.x[0]) {
+		if (f->has_preinit) {
+F( "extern bool _feature_preinit_%s(void);", f->modname)
+		}
+F( "extern bool _feature_init_%s(void);", f->modname)
+		if (f->has_end) {
+F( "extern bool _feature_end_%s(void);", f->modname)
+		}
+		if (f->is_requested) {
+F( "bool has_%s = false;", f->modname)
+		}
+		else if (f->has_end || f->has_evhandlers) {
+F( "static bool has_%s = false;", f->modname)
+		}
+	}
+_( "")
+_( "static void initfeatures(void) {")
+	for (struct feature *f = features.x[0]; f; f = f->hdr.x[0]) {
+		featdfs(out, f);
+	}
+_( "")
+	// note: old success message is moved in here, to get the ordering right
+_( "	con_colourmsg(RGBA(64, 255, 64, 255),")
+_( "			LONGNAME \" v\" VERSION \" successfully loaded\");")
+_( "	con_colourmsg(RGBA(255, 255, 255, 255), \" for game \");")
+_( "	con_colourmsg(RGBA(0, 255, 255, 255), \"%s\\n\", gameinfo_title);")
+_( "	struct con_colour white = {255, 255, 255, 255};")
+_( "	struct con_colour green = {128, 255, 128, 255};")
+_( "	struct con_colour red   = {255, 128, 128, 255};")
+_( "	con_colourmsg(&white, \"---- List of plugin features ---\\n\");");
+	for (const struct feature *f = features_bydesc.x[0]; f;
+			f = f->hdr_bydesc.x[0]) {
+F( "	con_colourmsg(status_%s == FEAT_OK ? &green : &red,", f->modname)
+F( "			featmsgs[(int)status_%s], \"%s\");", f->modname, f->desc)
+	}
+_( "}")
+_( "")
+_( "static void endfeatures(void) {")
+	for (struct feature **pp = endstack.data + endstack.sz - 1;
+			pp - endstack.data >= 0; --pp) {
+		if ((*pp)->has_end) {
+F( "	if (has_%s) _feature_end_%s();", (*pp)->modname, (*pp)->modname)
+		}
+	}
+_( "}")
+_( "")
+	if (fclose(out) == EOF) die("couldn't fully write featureinit.gen.h");
+
 	out = fopen(".build/include/evglue.gen.h", "wb");
 	if (!out) die("couldn't open evglue.gen.h");
-	H()
+	H_()
 	for (const struct event *e = events.x[0]; e; e = e->hdr.x[0]) {
+_( "")
 F( "void _evemit_%s(void) {", e->name)
-		for (const char **pp = e->handlers.data;
+		for (usize *pp = e->handlers.data;
 				pp - e->handlers.data < e->handlers.sz; ++pp) {
-F( "	void _evhandler_%s_%s(void);", *pp, e->name); // blegh.
-F( "	_evhandler_%s_%s();", *pp, e->name);
+		const char *modname = (const char *)(*pp & ~1ull);
+F( "	void _evhandler_%s_%s(void);", modname, e->name) // blegh.
+		if (*pp & 1ull) {
+			// note: has_* variables are already included by this point (above)
+F( "	if (has_%s) _evhandler_%s_%s();", modname, modname, e->name)
+		}
+		else {
+F( "	_evhandler_%s_%s();", modname, e->name)
+		}
 		}
 _( "}")
 	}
diff --git a/src/democustom.c b/src/democustom.c
index 0a1174f..c7de77b 100644
--- a/src/democustom.c
+++ b/src/democustom.c
@@ -22,12 +22,18 @@
 #include "demorec.h"
 #include "engineapi.h"
 #include "errmsg.h"
+#include "feature.h"
 #include "gamedata.h"
 #include "intdefs.h"
 #include "mem.h"
 #include "ppmagic.h"
 #include "vcall.h"
 
+FEATURE()
+REQUIRE(demorec)
+REQUIRE_GAMEDATA(vtidx_GetEngineBuildNumber)
+REQUIRE_GAMEDATA(vtidx_RecordPacket)
+
 static int nbits_msgtype, nbits_datalen;
 
 // The engine allows usermessages up to 255 bytes, we add 2 bytes of overhead,
@@ -107,12 +113,7 @@ static bool find_WriteMessages(void) {
 
 DECL_VFUNC_DYN(int, GetEngineBuildNumber)
 
-bool democustom_init(void) {
-	if (!has_vtidx_GetEngineBuildNumber || !has_vtidx_RecordPacket) {
-		errmsg_errorx("missing gamedata entries for this engine");
-		return false;
-	}
-
+INIT {
 	// More UncraftedkNowledge:
 	// > yeah okay so [the usermessage length is] 11 bits if the demo protocol
 	// > is 11 or if the game is l4d2 and the network protocol is 2042.
diff --git a/src/democustom.h b/src/democustom.h
index 9f9bbe9..a0a28b8 100644
--- a/src/democustom.h
+++ b/src/democustom.h
@@ -17,8 +17,6 @@
 #ifndef INC_DEMOCUSTOM_H
 #define INC_DEMOCUSTOM_H
 
-#include <stdbool.h>
-
 /* maximum length of a custom demo message, in bytes */
 #define DEMOCUSTOM_MSG_MAX 253
 
@@ -28,8 +26,6 @@
  */
 void democustom_write(const void *buf, int len);
 
-bool democustom_init(void);
-
 #endif
 
 // vi: sw=4 ts=4 noet tw=80 cc=80
diff --git a/src/demorec.c b/src/demorec.c
index 1fb5e8e..50128f0 100644
--- a/src/demorec.c
+++ b/src/demorec.c
@@ -21,6 +21,7 @@
 #include "con_.h"
 #include "engineapi.h"
 #include "errmsg.h"
+#include "feature.h"
 #include "gamedata.h"
 #include "gameinfo.h"
 #include "hook.h"
@@ -32,6 +33,9 @@
 #include "x86.h"
 #include "x86util.h"
 
+FEATURE("improved demo recording")
+REQUIRE_GAMEDATA(vtidx_StopRecording)
+
 DEF_CVAR(sst_autorecord, "Continuously record demos even after reconnecting", 1,
 		CON_ARCHIVE | CON_HIDDEN)
 
@@ -187,7 +191,7 @@ static inline bool find_recmembers(void *stoprecording) {
 			recording = mem_offset(demorecorder, mem_load32(p + 2));
 		}
 		if (recording && demonum) return true; // blegh
-		NEXT_INSN(p, "state variables");
+		NEXT_INSN(p, "recording state variables");
 	}
 #else // linux is probably different here idk
 #warning TODO(linux): implement linux equivalent (???)
@@ -195,11 +199,7 @@ static inline bool find_recmembers(void *stoprecording) {
 	return false;
 }
 
-bool demorec_init(void) {
-	if (!has_vtidx_StopRecording) {
-		errmsg_errorx("missing gamedata entries for this engine");
-		return false;
-	}
+INIT {
 	cmd_record = con_findcmd("record");
 	if (!cmd_record) { // can *this* even happen? I hope not!
 		errmsg_errorx("couldn't find \"record\" command");
@@ -240,7 +240,7 @@ bool demorec_init(void) {
 	return true;
 }
 
-void demorec_end(void) {
+END {
 	// avoid dumb edge case if someone somehow records and immediately unloads
 	if (*recording && *demonum == 0) *demonum = 1;
 	void **vtable = *(void ***)demorecorder;
diff --git a/src/demorec.h b/src/demorec.h
index 7306c0a..40f8c38 100644
--- a/src/demorec.h
+++ b/src/demorec.h
@@ -18,14 +18,9 @@
 #ifndef INC_DEMOREC_H
 #define INC_DEMOREC_H
 
-#include <stdbool.h>
-
 /* For internal use by democustom */
 extern void *demorecorder;
 
-bool demorec_init(void);
-void demorec_end(void);
-
 #endif
 
 // vi: sw=4 ts=4 noet tw=80 cc=80
diff --git a/src/engineapi.c b/src/engineapi.c
index 15c780a..cef085b 100644
--- a/src/engineapi.c
+++ b/src/engineapi.c
@@ -14,8 +14,8 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-#include <stdbool.h> // used in generated code
-#include <stdlib.h> // "
+#include <stdbool.h>
+#include <stdlib.h> // used in generated code
 #include <string.h> // "
 
 #include "con_.h"
diff --git a/src/ent.c b/src/ent.c
index 392fceb..9d69bf0 100644
--- a/src/ent.c
+++ b/src/ent.c
@@ -18,12 +18,15 @@
 
 #include "engineapi.h"
 #include "errmsg.h"
+#include "feature.h"
 #include "gamedata.h"
 #include "gametype.h"
 #include "intdefs.h"
 #include "mem.h"
 #include "vcall.h"
 
+FEATURE()
+
 DECL_VFUNC_DYN(void *, PEntityOfEntIndex, int)
 static struct edict **edicts = 0;
 
@@ -44,7 +47,7 @@ void *ent_get(int idx) {
 	return e->ent_unknown;
 }
 
-bool ent_init(void) {
+INIT {
 	// for PEntityOfEntIndex we don't really have to do any more init, we
 	// can just call the function later.
 	if (has_vtidx_PEntityOfEntIndex) return true;
diff --git a/src/ent.h b/src/ent.h
index 98657ce..049f27f 100644
--- a/src/ent.h
+++ b/src/ent.h
@@ -17,16 +17,11 @@
 #ifndef INC_ENT_H
 #define INC_ENT_H
 
-#include <stdbool.h>
-
 #include "engineapi.h"
 
 struct edict *ent_getedict(int idx);
 void *ent_get(int idx);
 
-bool ent_init(void);
-void ent_end(void);
-
 #endif
 
 // vi: sw=4 ts=4 noet tw=80 cc=80
diff --git a/src/event.h b/src/event.h
index 41965e9..e439201 100644
--- a/src/event.h
+++ b/src/event.h
@@ -24,7 +24,7 @@
 #define DEF_EVENT(evname) \
 	DECL_EVENT(evname) \
 	static inline void _evown_##evname(void) { _evemit_##evname(); }
-#define EMIT_EVENT(evname) _evown_##evname();
+#define EMIT_EVENT(evname) _evown_##evname()
 
 #define HANDLE_EVENT(evname) \
 	void _EVENT_CAT4(_evhandler_, MODULE_NAME, _, evname)(void) \
diff --git a/src/feature.h b/src/feature.h
new file mode 100644
index 0000000..5277bca
--- /dev/null
+++ b/src/feature.h
@@ -0,0 +1,94 @@
+/*
+ * Copyright © 2022 Michael Smith <mikesmiffy128@gmail.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+ * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef INC_FEATURE_H
+#define INC_FEATURE_H
+
+#include <stdbool.h>
+
+#define _FEATURE_CAT1(a, b) a##b
+#define _FEATURE_CAT(a, b) _FEATURE_CAT1(a, b)
+
+/*
+ * Declares that this translation unit implements a "feature" - a unit of
+ * plugin functionality.
+ *
+ * desc specifies a string to be displayed to the user. Omit this to declare an
+ * internal feature, which won't be advertised, but will be available to other
+ * features.
+ */
+#define FEATURE(... /*desc*/)
+
+/*
+ * Indicates that the specified feature is required for this feature to function.
+ * If that feature fails to initialise, this feature will not be enabled.
+ */
+#define REQUIRE(feature)
+
+/*
+ * Indicates that the specified feature should be initialised before this one,
+ * but is not a hard requirement.
+ *
+ * Presence of a feature can be tested for using has_<featurename>.
+ */
+#define REQUEST(featname) extern bool has_##featname;
+
+/*
+ * Indicates that the specified gamedata entry is required for this feature to
+ * function. If that entry is missing, this feature will not be enabled.
+ *
+ * Note that optional gamedata doesn't need to be specified here as it has no
+ * effect on whether this feature is loaded. It can simply be tested for using
+ * has_<entryname>.
+ */
+#define REQUIRE_GAMEDATA(feature)
+
+/*
+ * Indicates that this feature requires a global variable (such as a factory or
+ * globally-exposed engine interface) to be non-null in order to function. If
+ * the variable has a null/zero value prior to feature initialisation, this
+ * feature will not be enabled.
+ */
+#define REQUIRE_GLOBAL(varname)
+
+/*
+ * Defines the special feature init function which is unique to this translation
+ * unit. This should return true to indicate success, or false to indicate
+ * failure. Features which start to load will cause dependent features not to be
+ * started.
+ *
+ * Features are required to specify this function.
+ */
+#define INIT bool _FEATURE_CAT(_feature_init_, MODULE_NAME)(void) // { code... }
+
+/*
+ * Defines the special, optional feature shutdown function which is unique to
+ * this translation unit. This does not return a value, and may be either
+ * specified once, or left out if no cleanup is required for this feature.
+ */
+#define END void _FEATURE_CAT(_feature_end_, MODULE_NAME)(void) // { code... }
+
+/*
+ * Defines a conditional check to run prior to checking other requirements for
+ * this feature. This can be used to match a certain game type or conditionally
+ * register console variables, and should return true or false to indicate
+ * whether the feature should continue to initialise.
+ */
+#define PREINIT bool _FEATURE_CAT(_feature_preinit_, MODULE_NAME)(void) // {...}
+
+#endif
+
+// vi: sw=4 ts=4 noet tw=80 cc=80
diff --git a/src/fov.c b/src/fov.c
index 4ea9b2d..c7c72ed 100644
--- a/src/fov.c
+++ b/src/fov.c
@@ -24,6 +24,7 @@
 #include "errmsg.h"
 #include "ent.h"
 #include "event.h"
+#include "feature.h"
 #include "gametype.h"
 #include "hook.h"
 #include "intdefs.h"
@@ -31,8 +32,11 @@
 #include "sst.h"
 #include "vcall.h"
 #include "x86.h"
+#include "x86util.h"
+
+FEATURE("extended FOV range")
+REQUEST(ent)
 
-bool changedmax = false;
 DEF_CVAR_MINMAX_UNREG(fov_desired,
 		"Set the base field of view (SST reimplementation)", 75, 75, 120,
 		CON_HIDDEN | CON_ARCHIVE)
@@ -58,13 +62,7 @@ static bool find_SetDefaultFOV(struct con_cmd *fov) {
 					mem_loadoffset(p + 1));
 			return true;
 		}
-		int len = x86_len(p);
-		if (len == -1) {
-			errmsg_errorx("unknown or invalid instruction looking for %s",
-					"SetDefaultFOV");
-			return false;
-		}
-		p += len;
+		NEXT_INSN(p, "SetDefaultFOV");
 	}
 	return false;
 }
@@ -75,7 +73,7 @@ static void fovcb(struct con_var *v) {
 	if (player) orig_SetDefaultFOV(player, con_getvari(v));
 }
 
-// called by sst.c in ClientActive to ensure fov is applied on load
+// ensure FOV is applied on load, if the engine wouldn't do that itself
 HANDLE_EVENT(ClientActive) {
 	if (real_fov_desired == fov_desired) {
 		void *player = ent_get(1); // "
@@ -85,14 +83,15 @@ HANDLE_EVENT(ClientActive) {
 
 static struct con_cmd *cmd_fov;
 
-bool fov_init(bool has_ent) {
+PREINIT {
 	// could work for other games, but generally only portal 1 people want this
 	// (the rest of us consider this cheating and a problem for runs...)
-	if (!GAMETYPE_MATCHES(Portal1)) { return false; }
+	return GAMETYPE_MATCHES(Portal1);
+}
 
+INIT {
 	cmd_fov = con_findcmd("fov");
 	if (!cmd_fov) return false; // shouldn't really happen but just in case!
-
 	if (real_fov_desired = con_findvar("fov_desired")) {
 		// latest steampipe already goes up to 120 fov
 		if (real_fov_desired->parent->maxval == 120) return false;
@@ -122,7 +121,7 @@ bool fov_init(bool has_ent) {
 	return true;
 }
 
-void fov_end(void) {
+END {
 	if (real_fov_desired && real_fov_desired != fov_desired) {
 		real_fov_desired->parent->maxval = 90;
 		if (con_getvarf(real_fov_desired) > 90) {
diff --git a/src/hook.c b/src/hook.c
index 8465fbe..eacac4a 100644
--- a/src/hook.c
+++ b/src/hook.c
@@ -57,7 +57,7 @@ void *hook_inline(void *func_, void *target) {
 		// FIXME: these cases may result in somewhat dodgy error messaging. They
 		// shouldn't happen anyway though. Maybe if we're confident we just
 		// compile 'em out of release builds some day, but that sounds a little
-		// scary. For now prefering confusing messages over crashes, I guess.
+		// scary. For now preferring confusing messages over crashes, I guess.
 		if (func[len] == X86_CALL) {
 			con_warn("hook_inline: can't trampoline call instructions\n");
 			return 0;
diff --git a/src/l4dwarp.c b/src/l4dwarp.c
index 76aa230..5412b64 100644
--- a/src/l4dwarp.c
+++ b/src/l4dwarp.c
@@ -16,18 +16,23 @@
 
 #define _USE_MATH_DEFINES // ... windows.
 #include <math.h>
-#include <stdbool.h>
 
 #include "con_.h"
 #include "engineapi.h"
 #include "errmsg.h"
 #include "ent.h"
+#include "feature.h"
 #include "gamedata.h"
 #include "gametype.h"
 #include "intdefs.h"
 #include "mem.h"
 #include "vcall.h"
 
+FEATURE("Left 4 Dead warp testing")
+REQUIRE_GAMEDATA(off_entpos)
+REQUIRE_GAMEDATA(off_eyeang)
+REQUIRE_GAMEDATA(vtidx_Teleport)
+
 DECL_VFUNC_DYN(void *, GetBaseEntity)
 DECL_VFUNC_DYN(void, Teleport, const struct vec3f *pos, const struct vec3f *ang,
 		const struct vec3f *vel)
@@ -48,12 +53,11 @@ DEF_CCMD_HERE_UNREG(sst_l4d_testwarp, "Simulate a bot warping to you",
 			org->y + shift * sin(yaw), org->z}, 0, &(struct vec3f){0, 0, 0});
 }
 
-bool l4dwarp_init(void) {
-	if (!GAMETYPE_MATCHES(L4Dx)) return false;
-	if (!has_off_entpos || !has_off_eyeang || !has_vtidx_Teleport) {
-		errmsg_errorx("missing gamedata entries for this engine");
-		return false;
-	}
+PREINIT {
+	return GAMETYPE_MATCHES(L4Dx);
+}
+
+INIT {
 	con_reg(sst_l4d_testwarp);
 	return true;
 }
diff --git a/src/l4dwarp.h b/src/l4dwarp.h
deleted file mode 100644
index 5328fcf..0000000
--- a/src/l4dwarp.h
+++ /dev/null
@@ -1,26 +0,0 @@
-/*
- * Copyright © 2022 Michael Smith <mikesmiffy128@gmail.com>
- *
- * Permission to use, copy, modify, and/or distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
- * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
- * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
- * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
- * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
- * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
- * PERFORMANCE OF THIS SOFTWARE.
- */
-
-#ifndef INC_L4DWARP_H
-#define INC_L4DWARP_H
-
-#include <stdbool.h>
-
-bool l4dwarp_init(void);
-
-#endif
-
-// vi: sw=4 ts=4 noet tw=80 cc=80
diff --git a/src/nosleep.c b/src/nosleep.c
index 5618ba9..07a5500 100644
--- a/src/nosleep.c
+++ b/src/nosleep.c
@@ -14,16 +14,19 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-#include <stdbool.h>
-
 #include "con_.h"
 #include "engineapi.h"
 #include "errmsg.h"
+#include "feature.h"
 #include "gamedata.h"
 #include "hook.h"
 #include "os.h"
 #include "vcall.h"
 
+FEATURE("inactive window sleep adjustment")
+REQUIRE_GAMEDATA(vtidx_SleepUntilInput)
+REQUIRE_GLOBAL(factory_inputsystem)
+
 DEF_CVAR_UNREG(engine_no_focus_sleep,
 		"Delay while tabbed out (SST reimplementation)", 50,
 		CON_ARCHIVE | CON_HIDDEN)
@@ -36,19 +39,13 @@ static void VCALLCONV hook_SleepUntilInput(void *this, int timeout) {
 	orig_SleepUntilInput(this, con_getvari(engine_no_focus_sleep));
 }
 
-bool nosleep_init(void) {
-	struct con_var *v = con_findvar("engine_no_focus_sleep");
-	if (v) return false; // no need!
+PREINIT {
+	if (con_findvar("engine_no_focus_sleep")) return false;
 	con_reg(engine_no_focus_sleep);
-	// TODO(featgen): auto-check these factories
-	if (!factory_inputsystem) {
-		errmsg_errorx("missing required factories");
-		return false;
-	}
-	if (!has_vtidx_SleepUntilInput) {
-		errmsg_errorx("missing gamedata entries for this engine");
-		return false;
-	}
+	return true;
+}
+
+INIT {
 	void *insys = factory_inputsystem("InputSystemVersion001", 0);
 	if (!insys) {
 		errmsg_errorx("couldn't get input system interface");
@@ -66,7 +63,7 @@ bool nosleep_init(void) {
 	return true;
 }
 
-void nosleep_end(void) {
+END {
 	unhook_vtable(vtable, vtidx_SleepUntilInput, (void *)orig_SleepUntilInput);
 }
 
diff --git a/src/nosleep.h b/src/nosleep.h
deleted file mode 100644
index 4d5237f..0000000
--- a/src/nosleep.h
+++ /dev/null
@@ -1,27 +0,0 @@
-/*
- * Copyright © 2022 Michael Smith <mikesmiffy128@gmail.com>
- *
- * Permission to use, copy, modify, and/or distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
- * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
- * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
- * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
- * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
- * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
- * PERFORMANCE OF THIS SOFTWARE.
- */
-
-#ifndef INC_NOSLEEP_H
-#define INC_NOSLEEP_H
-
-#include <stdbool.h>
-
-bool nosleep_init(void);
-void nosleep_end(void);
-
-#endif
-
-// vi: sw=4 ts=4 noet tw=80 cc=80
diff --git a/src/portalcolours.c b/src/portalcolours.c
index 750ee19..231aa01 100644
--- a/src/portalcolours.c
+++ b/src/portalcolours.c
@@ -21,13 +21,18 @@
 #include "engineapi.h"
 #include "errmsg.h"
 #include "gametype.h"
+#include "feature.h"
 #include "hook.h"
 #include "intdefs.h"
 #include "mem.h"
 #include "os.h"
 #include "ppmagic.h"
+#include "sst.h"
 #include "vcall.h"
 
+FEATURE("portal gun colour customisation")
+REQUIRE_GLOBAL(clientlib)
+
 // It's like the thing Portal Tools does, but at runtime!
 
 DEF_CVAR(sst_portal_colour0, "Crosshair colour for gravity beam (hex)",
@@ -119,8 +124,11 @@ static bool find_UTIL_Portal_Color(void *base) {
 	return false;
 }
 
-bool portalcolours_init(void *clientlib) { // ... should libs be globals?
-	if (!GAMETYPE_MATCHES(Portal)) return false;
+PREINIT {
+	return GAMETYPE_MATCHES(Portal1);
+}
+
+INIT {
 #ifdef _WIN32
 	if (!find_UTIL_Portal_Color(clientlib)) {
 		errmsg_errorx("couldn't find UTIL_Portal_Color");
@@ -145,7 +153,7 @@ bool portalcolours_init(void *clientlib) { // ... should libs be globals?
 #endif
 }
 
-void portalcolours_end(void) {
+END {
 	unhook_inline((void *)orig_UTIL_Portal_Color);
 }
 
diff --git a/src/portalcolours.h b/src/portalcolours.h
deleted file mode 100644
index 2dd4bb5..0000000
--- a/src/portalcolours.h
+++ /dev/null
@@ -1,27 +0,0 @@
-/*
- * Copyright © 2022 Michael Smith <mikesmiffy128@gmail.com>
- *
- * Permission to use, copy, modify, and/or distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
- * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
- * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
- * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
- * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
- * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
- * PERFORMANCE OF THIS SOFTWARE.
- */
-
-#ifndef INC_PORTALCOLOURS_H
-#define INC_PORTALCOLOURS_H
-
-#include <stdbool.h>
-
-bool portalcolours_init(void *clientlib);
-void portalcolours_end();
-
-#endif
-
-// vi: sw=4 ts=4 noet tw=80 cc=80
diff --git a/src/rinput.c b/src/rinput.c
index 1b81cf5..a7ad8d8 100644
--- a/src/rinput.c
+++ b/src/rinput.c
@@ -17,14 +17,16 @@
 // NOTE: compiled on Windows only. All Linux Source releases are new enough to
 // have raw input already.
 
-#include <stdbool.h>
 #include <Windows.h>
 
 #include "con_.h"
 #include "hook.h"
 #include "errmsg.h"
+#include "feature.h"
 #include "intdefs.h"
 
+FEATURE("raw mouse input")
+
 // We reimplement m_rawinput by hooking cursor functions in the same way as
 // RInput (it's way easier than replacing all the mouse-handling internals of
 // the actual engine). We also take the same window class it does in order to
@@ -76,11 +78,14 @@ static int __stdcall hook_SetCursorPos(int x, int y) {
 	return orig_SetCursorPos(x, y);
 }
 
-bool rinput_init(void) {
+PREINIT {
 	if (con_findvar("m_rawinput")) return false; // no need!
 	// create cvar hidden so if we fail to init, setting can still be preserved
 	con_reg(m_rawinput);
+	return true;
+}
 
+INIT {
 	WNDCLASSEXW wc = {
 		.cbSize = sizeof(wc),
 		// cast because inproc is binary-compatible but doesn't use stupid
@@ -139,7 +144,7 @@ e0:	UnregisterClassW(L"RInput", 0);
 	return false;
 }
 
-void rinput_end(void) {
+END {
 	RAWINPUTDEVICE rd = {
 		.dwFlags = RIDEV_REMOVE,
 		.hwndTarget = 0,
diff --git a/src/rinput.h b/src/rinput.h
deleted file mode 100644
index e89a363..0000000
--- a/src/rinput.h
+++ /dev/null
@@ -1,29 +0,0 @@
-/*
- * Copyright © 2022 Michael Smith <mikesmiffy128@gmail.com>
- *
- * Permission to use, copy, modify, and/or distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
- * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
- * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
- * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
- * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
- * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
- * PERFORMANCE OF THIS SOFTWARE.
- */
-
-#ifndef INC_RINPUT_H
-#define INC_RINPUT_H
-#ifdef _WIN32
-
-#include <stdbool.h>
-
-bool rinput_init(void);
-void rinput_end(void);
-
-#endif
-#endif
-
-// vi: sw=4 ts=4 noet tw=80 cc=80
diff --git a/src/sst.c b/src/sst.c
index d2576f6..c959d65 100644
--- a/src/sst.c
+++ b/src/sst.c
@@ -22,26 +22,15 @@
 #endif
 
 #include "ac.h"
-#include "bind.h"
-#include "alias.h"
-#include "autojump.h"
 #include "con_.h"
-#include "democustom.h"
-#include "demorec.h"
 #include "engineapi.h"
 #include "errmsg.h"
-#include "ent.h"
 #include "event.h"
-#include "fov.h"
 #include "fixes.h"
 #include "gameinfo.h"
 #include "gametype.h"
 #include "hook.h"
-#include "l4dwarp.h"
-#include "nosleep.h"
-#include "portalcolours.h"
 #include "os.h"
-#include "rinput.h"
 #include "vcall.h"
 #include "version.h"
 
@@ -53,8 +42,9 @@
 
 static int ifacever;
 
-// we need to keep this reference to dlclose() it later - see below
-static void *clientlib = 0;
+// XXX: exposing this clumsily to portalcolours. we should have a better way of
+// exposing lib handles in general, probably.
+void *clientlib = 0;
 
 #ifdef _WIN32
 extern long __ImageBase; // this is actually the PE header struct but don't care
@@ -189,16 +179,6 @@ static void VCALLCONV SetCommandClient(void *this, int i) { con_cmdclient = i; }
 static const void **vtable_firstdiff;
 static const void *const *const plugin_obj;
 
-// TODO(featgen): I wanted some nice fancy automatic feature system that
-// figures out the dependencies at build time and generates all the init glue
-// but we want to actually release the plugin this decade so for now I'm just
-// plonking some bools here and worrying about it later. :^)
-static bool has_ac = false, has_autojump = false, has_demorec = false,
-		has_fov = false, has_nosleep = false, has_portalcolours = false;
-#ifdef _WIN32
-static bool has_rinput = false;
-#endif
-
 static bool already_loaded = false, skip_unload = false;
 
 #define RGBA(r, g, b, a) (&(struct con_colour){(r), (g), (b), (a)})
@@ -208,28 +188,12 @@ static const char *updatenotes = "\
 * various internal cleanup\n\
 ";
 
+#include <featureinit.gen.h>
+
 static void do_featureinit(void) {
-	bool has_bind = bind_init();
-	if (has_bind) has_ac = ac_init();
-	alias_init();
-	has_autojump = autojump_init();
-	has_demorec = demorec_init();
-	if (has_demorec) democustom_init();
-	bool has_ent = ent_init();
-	has_fov = fov_init(has_ent);
-	if (has_ent) l4dwarp_init();
-	has_nosleep = nosleep_init();
-	if (clientlib) has_portalcolours = portalcolours_init(clientlib);
-#ifdef _WIN32
-	has_rinput = rinput_init();
-#endif
+	initfeatures();
 	fixes_apply();
 
-	con_colourmsg(RGBA(64, 255, 64, 255),
-			LONGNAME " v" VERSION " successfully loaded");
-	con_colourmsg(RGBA(255, 255, 255, 255), " for game ");
-	con_colourmsg(RGBA(0, 255, 255, 255), "%s\n", gameinfo_title);
-
 	// if we're autoloaded and the external autoupdate script downloaded a new
 	// version, let the user know about the cool new stuff!
 	if (getenv("SST_UPDATED")) {
@@ -416,16 +380,7 @@ static void do_unload(void) {
 	}
 #endif
 
-	if (has_ac) ac_end();
-	if (has_autojump) autojump_end();
-	if (has_demorec) demorec_end();
-	if (has_fov) fov_end(); // dep on ent
-	if (has_nosleep) nosleep_end();
-	if (has_portalcolours) portalcolours_end();
-#ifdef _WIN32
-	if (has_rinput) rinput_end();
-#endif
-
+	endfeatures();
 #ifdef __linux__
 	if (clientlib) dlclose(clientlib);
 #endif
@@ -475,12 +430,19 @@ DEF_CVAR(_sst_onload_echo, "EXPERIMENTAL! Don't rely on this existing!", "",
 		CON_HIDDEN)
 
 DEF_EVENT(ClientActive)
+DEF_EVENT(Tick)
+
+// Quick and easy server tick event. Eventually, we might want a deeper hook
+// for anything timing-sensitive, but this will do for our current needs.
+static void VCALLCONV GameFrame(void *this, bool simulating) {
+	EMIT_EVENT(Tick);
+}
 
 static void VCALLCONV ClientActive(void *this, struct edict *player) {
 	// XXX: it's kind of dumb that we get handed the edict here then go look it
 	// up again in fov.c but I can't be bothered refactoring any further now
 	// that this finally works, do something later lol
-	EMIT_EVENT(ClientActive)
+	EMIT_EVENT(ClientActive);
 
 	// continuing dumb portal hack. didn't even seem worth adding a feature for
 	if (has_vtidx_ServerCommand && con_getvarstr(_sst_onload_echo)[0]) {
@@ -510,7 +472,7 @@ static const void *vtable[MAX_VTABLE_FUNCS] = {
 	(void *)&GetPluginDescription,
 	(void *)&nop_p_v,	// LevelInit
 	(void *)&nop_pii_v,	// ServerActivate
-	(void *)&nop_b_v,	// GameFrame
+	(void *)&GameFrame,	// GameFrame
 	(void *)&nop_v_v,	// LevelShutdown
 	(void *)&ClientActive
 	// At this point, Alien Swarm and Portal 2 add ClientFullyConnect, so we
diff --git a/src/sst.h b/src/sst.h
index 247346b..d432480 100644
--- a/src/sst.h
+++ b/src/sst.h
@@ -19,7 +19,12 @@
 
 #include "event.h"
 
+/* misc stuff that doesn't belong anywhere else */
+
 DECL_EVENT(ClientActive)
+DECL_EVENT(Tick)
+
+extern void *clientlib;
 
 #endif