Refactors MODsuit module rendering and allows overslotted parts to show items they overslot when unsealed (#90414)

## About The Pull Request

MODsuit modules now render on the part they're attached to, that being
first part if required_slots is set, otherwise defaulting to the control
module. Instead of using icon ops and a cache, module masking (used by
armor boosters and insignias) will instead render the module on all
parts, each overlay alpha filtered using the worn piece as the mask. To
do this we also migrate modules to separate_worn_overlays, which fixes
the issue where they'd always get painted the same color as the back
piece, ignoring use_mod_colors's value (which is FALSE by default). So
now modules that inherit MOD's color like armor booster will be painted
accordingly to their piece.
This also means that modules actually layer properly, and don't go ontop
of items that they should be under.

Additionally, whenever gloves or boots overslot an item, the overslotted
item will still render underneath them if they're unsealed. Because it
looks weird when your gloves disappear when you extend your MODsuit
ones.


![dreamseeker_BaWjJBcMVO](https://github.com/user-attachments/assets/2b374913-7761-4b54-9bbd-cbd57d343fd6)

Look at that hip look, she'd have bare hands and ankles without this PR.

Closes #90370

## Why It's Good For The Game

Fixes a bunch of visual jank that looks weird, and overslotting
displaying overslotted item is just behavior you'd expect normally.

## Changelog
🆑
add: When a MODsuit piece overslots an item, it will now render beneath
that piece as long as its unsealed.
refactor: Refactored how MODsuit modules are rendered, report any bugs
on GitHub!
/🆑

code/modules/mod/mod_activation.dm

@@ -93,7 +93,7 @@
 				RegisterSignal(part, COMSIG_ATOM_EXITED, PROC_REF(on_overslot_exit))
 	if(wearer.equip_to_slot_if_possible(part, part.slot_flags, qdel_on_fail = FALSE, disable_warning = TRUE))
 		ADD_TRAIT(part, TRAIT_NODROP, MOD_TRAIT)
-		wearer.update_clothing(slot_flags)
+		wearer.update_clothing(slot_flags|part.slot_flags)
 		SEND_SIGNAL(src, COMSIG_MOD_PART_DEPLOYED, user, part_datum)
 		if(user)
 			wearer.visible_message(span_notice("[wearer]'s [part.name] deploy[part.p_s()] with a mechanical hiss."),
@@ -131,7 +131,9 @@
 		return FALSE
 	if(SEND_SIGNAL(src, COMSIG_MOD_PART_RETRACTING, user, part_datum) & MOD_CANCEL_RETRACTION)
 		return FALSE
+	var/unsealing = FALSE
 	if(active && part_datum.sealed)
+		unsealing = TRUE
 		if(instant)
 			seal_part(part, is_sealed = FALSE)
 		else if(!delayed_seal_part(part))
@@ -144,13 +146,14 @@
 		var/obj/item/overslot = part_datum.overslotting
 		if(!QDELING(wearer) && !wearer.equip_to_slot_if_possible(overslot, overslot.slot_flags, qdel_on_fail = FALSE, disable_warning = TRUE))
 			wearer.dropItemToGround(overslot, force = TRUE, silent = TRUE)
-	wearer.update_clothing(slot_flags)
+	wearer.update_clothing(slot_flags|part.slot_flags)
 	if(!user)
 		return TRUE
 	wearer.visible_message(span_notice("[wearer]'s [part.name] retract[part.p_s()] back into [src] with a mechanical hiss."),
 		span_notice("[part] retract[part.p_s()] back into [src] with a mechanical hiss."),
 		span_hear("You hear a mechanical hiss."))
-	playsound(src, 'sound/vehicles/mecha/mechmove03.ogg', 25, TRUE, SHORT_RANGE_SOUND_EXTRARANGE)
+	if (!unsealing)
+		playsound(src, 'sound/vehicles/mecha/mechmove03.ogg', 25, TRUE, SHORT_RANGE_SOUND_EXTRARANGE)
 	return TRUE
 
 /// Starts the activation sequence, where parts of the suit activate one by one until the whole suit is on.
@@ -268,7 +271,6 @@
 		part.heat_protection = NONE
 		part.cold_protection = NONE
 		part.alternate_worn_layer = part_datum.unsealed_layer
-	generate_suit_mask()
 	update_speed()
 	wearer.update_clothing(part.slot_flags | slot_flags)
 	wearer.update_obscured_slots(part.visor_flags_inv)
@@ -281,7 +283,7 @@
 		for(var/obj/item/mod/module/module as anything in modules)
 			if(module.part_activated || !module.has_required_parts(mod_parts, need_active = TRUE))
 				continue
-			module.on_part_activation()
+				module.on_part_activation()
 			module.part_activated = TRUE
 	else
 		for(var/obj/item/mod/module/module as anything in modules)
@@ -300,23 +302,16 @@
 	active = is_on
 	if(active)
 		for(var/obj/item/mod/module/module as anything in modules)
-			if(module.part_activated || !module.has_required_parts(mod_parts, need_active = TRUE))
-				continue
-			module.on_part_activation()
-			module.part_activated = TRUE
+			if(!module.part_activated && module.has_required_parts(mod_parts, need_active = TRUE))
+				module.on_part_activation()
 	else
 		for(var/obj/item/mod/module/module as anything in modules)
 			if(!module.part_activated)
 				continue
 			module.on_part_deactivation()
-			module.part_activated = FALSE
-			if(!module.active || (module.allow_flags & MODULE_ALLOW_INACTIVE))
-				continue
-			module.deactivate(display_message = FALSE)
 	update_charge_alert()
 	update_appearance(UPDATE_ICON_STATE)
-	generate_suit_mask()
-	wearer.update_clothing(slot_flags)
+	wearer.update_clothing()
 
 /// Quickly deploys all the suit parts and if successful, seals them and turns on the suit. Intended mostly for outfits.
 /obj/item/mod/control/proc/quick_activation()

code/modules/mod/mod_control.dm

@@ -114,13 +114,10 @@
 	if(core)
 		QDEL_NULL(core)
 	QDEL_NULL(mod_link)
-	for(var/datum/mod_part/part_datum as anything in get_part_datums(all = TRUE))
-		var/obj/item/part_item = part_datum.part_item
-		part_datum.part_item = null
-		part_datum.overslotting = null
-		mod_parts -= part_datum
-		if(!QDELING(part_item))
-			qdel(part_item)
+	for(var/part_key in mod_parts)
+		var/datum/mod_part/part_datum = mod_parts[part_key]
+		mod_parts -= part_key
+		qdel(part_datum)
 	return ..()
 
 /obj/item/mod/control/atom_destruction(damage_flag)
@@ -443,11 +440,14 @@
 	CRASH("get_part_datum called with incorrect item [part] passed.")
 
 /obj/item/mod/control/proc/get_part_from_slot(slot)
-	var/datum/mod_part/part = mod_parts["[slot]"]
-	return part?.part_item
+	RETURN_TYPE(/obj/item)
+	return get_part_datum_from_slot(slot)?.part_item
 
 /obj/item/mod/control/proc/get_part_datum_from_slot(slot)
-	return mod_parts["[slot]"]
+	RETURN_TYPE(/datum/mod_part)
+	for (var/part_key in mod_parts)
+		if (text2num(part_key) & slot)
+			return mod_parts[part_key]
 
 /obj/item/mod/control/proc/set_wearer(mob/living/carbon/human/user)
 	if(wearer == user)
@@ -481,21 +481,6 @@
 		covered_slots |= part.slot_flags
 	return covered_slots
 
-/obj/item/mod/control/proc/generate_suit_mask()
-	var/list/parts = get_parts(all = TRUE)
-	var/covered_slots = get_sealed_slots(parts)
-	if(GLOB.mod_masks[skin])
-		if(GLOB.mod_masks[skin]["[covered_slots]"])
-			return GLOB.mod_masks[skin]["[covered_slots]"]
-	else
-		GLOB.mod_masks[skin] = list()
-	var/icon/slot_mask = icon('icons/blanks/32x32.dmi', "nothing")
-	for(var/obj/item/part as anything in parts)
-		slot_mask.Blend(icon(part.worn_icon, part.icon_state), ICON_OVERLAY)
-	slot_mask.Blend("#fff", ICON_ADD)
-	GLOB.mod_masks[skin]["[covered_slots]"] = slot_mask
-	return GLOB.mod_masks[skin]["[covered_slots]"]
-
 /obj/item/mod/control/proc/clean_up()
 	if(QDELING(src))
 		unset_wearer()
@@ -602,7 +587,6 @@
 	modules += new_module
 	complexity += new_module.complexity
 	new_module.mod = src
-	new_module.RegisterSignal(src, COMSIG_ITEM_GET_WORN_OVERLAYS, TYPE_PROC_REF(/obj/item/mod/module, add_module_overlay))
 	new_module.on_install()
 	if(wearer)
 		new_module.on_equip()
@@ -622,7 +606,6 @@
 		old_module.on_part_deactivation(deleting = deleting)
 		if(old_module.active)
 			old_module.deactivate(display_message = !deleting, deleting = deleting)
-	old_module.UnregisterSignal(src, COMSIG_ITEM_GET_WORN_OVERLAYS)
 	old_module.on_uninstall(deleting = deleting)
 	QDEL_LIST_ASSOC_VAL(old_module.pinned_to)
 	old_module.mod = null

code/modules/mod/mod_part.dm

@@ -18,5 +18,29 @@
 	var/obj/item/overslotting = null
 
 /datum/mod_part/Destroy()
+	// To avoid qdel loops in MOD control units, since they're also a part
+	if (!QDELING(part_item))
+		qdel(part_item)
 	part_item = null
+	overslotting = null
 	return ..()
+
+/datum/mod_part/proc/set_item(obj/item/new_part)
+	part_item = new_part
+	RegisterSignal(part_item, COMSIG_ITEM_GET_SEPARATE_WORN_OVERLAYS, PROC_REF(get_separate_worn_overlays))
+
+// If we're overslotting an item, add its visual as an underlay
+/datum/mod_part/proc/get_separate_worn_overlays(obj/item/source, list/overlays, mutable_appearance/standing, mutable_appearance/draw_target, isinhands, icon_file)
+	SIGNAL_HANDLER
+
+	if (!overslotting || sealed)
+		return
+
+	var/checked_slot = source.slot_flags
+	if (ismob(source.loc))
+		var/mob/as_mob = source.loc
+		checked_slot = as_mob.get_slot_by_item(source)
+	var/mutable_appearance/worn_overlay = overslotting.build_worn_icon(default_layer = -draw_target.layer + 0.1, default_icon_file = get_default_icon_by_slot(checked_slot))
+	for (var/mutable_appearance/overlay in worn_overlay.overlays)
+		overlay.layer = draw_target.layer + 0.1
+	overlays += worn_overlay

code/modules/mod/mod_theme.dm

@@ -106,7 +106,7 @@
 	mod.ui_theme = ui_theme
 	mod.charge_drain = charge_drain
 	var/datum/mod_part/control_part_datum = new()
-	control_part_datum.part_item = mod
+	control_part_datum.set_item(mod)
 	mod.mod_parts["[mod.slot_flags]"] = control_part_datum
 	for(var/path in variants[default_skin])
 		if(!ispath(path))
@@ -116,7 +116,7 @@
 			var/obj/item/clothing/chestplate = mod_part
 			chestplate.allowed |= allowed_suit_storage
 		var/datum/mod_part/part_datum = new()
-		part_datum.part_item = mod_part
+		part_datum.set_item(mod_part)
 		mod.mod_parts["[mod_part.slot_flags]"] = part_datum
 		parts += mod_part
 

code/modules/mod/modules/_module.dm

@@ -172,9 +172,9 @@
 			update_signal(used_button)
 			balloon_alert(mod.wearer, "[src] activated, [used_button]-click to use")
 	active = TRUE
-	mod.wearer.update_clothing(mod.slot_flags)
 	SEND_SIGNAL(src, COMSIG_MODULE_ACTIVATED)
 	on_activation()
+	update_clothing_slots()
 	return TRUE
 
 /// Called when the module is deactivated
@@ -191,11 +191,22 @@
 		else
 			UnregisterSignal(mod.wearer, used_signal)
 			used_signal = null
-	mod.wearer.update_clothing(mod.slot_flags)
 	SEND_SIGNAL(src, COMSIG_MODULE_DEACTIVATED, mod.wearer)
 	on_deactivation(display_message = TRUE, deleting = FALSE)
+	update_clothing_slots()
 	return TRUE
 
+/// Call to update all slots visually affected by this module
+/obj/item/mod/module/proc/update_clothing_slots()
+	var/updated_slots = mod.slot_flags
+	if (mask_worn_overlay)
+		for (var/obj/item/part as anything in mod.get_parts())
+			updated_slots |= part.slot_flags
+	else if (length(required_slots))
+		for (var/slot in required_slots)
+			updated_slots |= slot
+	mod.wearer.update_clothing(updated_slots)
+
 /// Called when the module is used
 /obj/item/mod/module/proc/used()
 	if(!COOLDOWN_FINISHED(src, cooldown_timer))
@@ -212,7 +223,7 @@
 		return FALSE
 	start_cooldown()
 	addtimer(CALLBACK(mod.wearer, TYPE_PROC_REF(/mob, update_clothing), mod.slot_flags), cooldown_time+1) //need to run it a bit after the cooldown starts to avoid conflicts
-	mod.wearer.update_clothing(mod.slot_flags)
+	update_clothing_slots()
 	SEND_SIGNAL(src, COMSIG_MODULE_USED)
 	on_use()
 	return TRUE
@@ -263,11 +274,38 @@
 
 /// Called from MODsuit's install() proc, so when the module is installed
 /obj/item/mod/module/proc/on_install()
-	return
+	SHOULD_CALL_PARENT(TRUE)
+
+	if (mask_worn_overlay)
+		for (var/obj/item/part as anything in mod.get_parts(all = TRUE))
+			RegisterSignal(part, COMSIG_ITEM_GET_SEPARATE_WORN_OVERLAYS, PROC_REF(add_module_overlay))
+		return
+
+	if (!length(required_slots))
+		RegisterSignal(mod, COMSIG_ITEM_GET_SEPARATE_WORN_OVERLAYS, PROC_REF(add_module_overlay))
+		return
+
+	var/obj/item/part = mod.get_part_from_slot(required_slots[1])
+	RegisterSignal(part, COMSIG_ITEM_GET_SEPARATE_WORN_OVERLAYS, PROC_REF(add_module_overlay))
 
 /// Called from MODsuit's uninstall() proc, so when the module is uninstalled
 /obj/item/mod/module/proc/on_uninstall(deleting = FALSE)
-	return
+	SHOULD_CALL_PARENT(TRUE)
+
+	if (deleting)
+		return
+
+	if (mask_worn_overlay)
+		for (var/obj/item/part as anything in mod.get_parts(all = TRUE))
+			UnregisterSignal(part, COMSIG_ITEM_GET_SEPARATE_WORN_OVERLAYS)
+		return
+
+	if (!length(required_slots))
+		UnregisterSignal(mod, COMSIG_ITEM_GET_SEPARATE_WORN_OVERLAYS)
+		return
+
+	var/obj/item/part = mod.get_part_from_slot(required_slots[1])
+	UnregisterSignal(part, COMSIG_ITEM_GET_SEPARATE_WORN_OVERLAYS)
 
 /// Called when the MODsuit is activated
 /obj/item/mod/module/proc/on_part_activation()
@@ -335,26 +373,44 @@
 		qdel(src)
 
 /// Adds the worn overlays to the suit.
-/obj/item/mod/module/proc/add_module_overlay(obj/item/source, list/overlays, mutable_appearance/standing, isinhands, icon_file)
+/obj/item/mod/module/proc/add_module_overlay(obj/item/source, list/overlays, mutable_appearance/standing, mutable_appearance/draw_target, isinhands, icon_file)
 	SIGNAL_HANDLER
 
-	overlays += generate_worn_overlay(standing)
+	if (isinhands)
+		return
+
+	var/list/added_overlays = generate_worn_overlay(source, standing)
+	if (!added_overlays)
+		return
+
+	if (!mask_worn_overlay)
+		overlays += added_overlays
+		return
+
+	for (var/mutable_appearance/overlay as anything in added_overlays)
+		overlay.add_filter("mod_mask_overlay", 1, alpha_mask_filter(icon = icon(draw_target.icon, draw_target.icon_state)))
+		overlays += overlay
 
 /// Generates an icon to be used for the suit's worn overlays
-/obj/item/mod/module/proc/generate_worn_overlay(mutable_appearance/standing)
+/obj/item/mod/module/proc/generate_worn_overlay(obj/item/source, mutable_appearance/standing)
+	if(!mask_worn_overlay)
+		if(!has_required_parts(mod.mod_parts, need_active = TRUE))
+			return
+	else
+		var/datum/mod_part/part_datum = mod.get_part_datum(source)
+		if (!part_datum?.sealed)
+			return
+
 	. = list()
-	if(!mod.active || !has_required_parts(mod.mod_parts, need_active = TRUE))
-		return
 	var/used_overlay = get_current_overlay_state()
 	if (!used_overlay)
 		return
-	var/mutable_appearance/module_icon
-	if(mask_worn_overlay)
-		module_icon = mutable_appearance(get_module_icon_cache(used_overlay), layer = standing.layer + 0.1)
-	else
-		module_icon = mutable_appearance(overlay_icon_file, used_overlay, layer = standing.layer + 0.1)
-	if(!use_mod_colors)
-		module_icon.appearance_flags |= RESET_COLOR
+
+	var/mutable_appearance/module_icon = mutable_appearance(overlay_icon_file, used_overlay, layer = standing.layer + 0.1)
+	if(use_mod_colors)
+		module_icon.color = mod.color
+		if (mod.cached_color_filter)
+			module_icon = filter_appearance_recursive(module_icon, mod.cached_color_filter)
 
 	. += module_icon
 	SEND_SIGNAL(src, COMSIG_MODULE_GENERATE_WORN_OVERLAY, ., standing)
@@ -368,22 +424,6 @@
 		return overlay_state_inactive
 	return null
 
-/obj/item/mod/module/proc/get_module_icon_cache(used_overlay)
-	var/covered_slots = mod.get_sealed_slots(mod.get_parts(all = TRUE))
-	if (GLOB.mod_module_overlays[mod.skin])
-		if (GLOB.mod_module_overlays[mod.skin]["[covered_slots]"])
-			if (GLOB.mod_module_overlays[mod.skin]["[covered_slots]"][used_overlay])
-				return GLOB.mod_module_overlays[mod.skin]["[covered_slots]"][used_overlay]
-		else
-			GLOB.mod_module_overlays[mod.skin]["[covered_slots]"] = list()
-	else
-		GLOB.mod_module_overlays[mod.skin] = list()
-		GLOB.mod_module_overlays[mod.skin]["[covered_slots]"] = list()
-	var/icon/mod_mask = icon(mod.generate_suit_mask())
-	mod_mask.Blend(icon(overlay_icon_file, used_overlay), ICON_MULTIPLY)
-	GLOB.mod_module_overlays[mod.skin]["[covered_slots]"][used_overlay] = mod_mask
-	return GLOB.mod_module_overlays[mod.skin]["[covered_slots]"][used_overlay]
-
 /// Updates the signal used by active modules to be activated
 /obj/item/mod/module/proc/update_signal(value)
 	switch(value)

code/modules/mod/modules/modules_antag.dm

@@ -90,7 +90,7 @@
 	if (!active)
 		module_slowdowns += space_slowdown
 
-/obj/item/mod/module/armor_booster/generate_worn_overlay(mutable_appearance/standing)
+/obj/item/mod/module/armor_booster/generate_worn_overlay(obj/item/source, mutable_appearance/standing)
 	overlay_state_inactive = "[initial(overlay_state_inactive)]-[mod.skin]"
 	overlay_state_active = "[initial(overlay_state_active)]-[mod.skin]"
 	return ..()
@@ -105,9 +105,11 @@
 		REMOVE_TRAIT(mod.wearer, TRAIT_HEAD_INJURY_BLOCKED, REF(src))
 
 /obj/item/mod/module/armor_booster/on_install()
+	. = ..()
 	RegisterSignal(mod, COMSIG_MOD_GET_VISOR_OVERLAY, PROC_REF(on_visor_overlay))
 
-/obj/item/mod/module/armor_booster/on_uninstall(deleting)
+/obj/item/mod/module/armor_booster/on_uninstall(deleting = FALSE)
+	. = ..()
 	UnregisterSignal(mod, COMSIG_MOD_GET_VISOR_OVERLAY)
 
 /obj/item/mod/module/armor_booster/proc/on_visor_overlay(datum/source,  mutable_appearance/standing, list/overrides)
@@ -241,7 +243,7 @@
 	overlay_state_inactive = "module_insignia"
 	mask_worn_overlay = TRUE
 
-/obj/item/mod/module/insignia/generate_worn_overlay(mutable_appearance/standing)
+/obj/item/mod/module/insignia/generate_worn_overlay(obj/item/source, mutable_appearance/standing)
 	overlay_state_inactive = "[initial(overlay_state_inactive)]-[mod.skin]"
 	. = ..()
 	for(var/mutable_appearance/appearance as anything in .)
@@ -409,6 +411,7 @@
 	var/obj/item/current_disguise
 
 /obj/item/mod/module/chameleon/on_install()
+	. = ..()
 	var/list/all_disguises = sort_list(subtypesof(get_path_by_slot(mod.slot_flags)), GLOBAL_PROC_REF(cmp_typepaths_asc))
 	for(var/clothing_path in all_disguises)
 		var/obj/item/clothing = clothing_path
@@ -418,6 +421,7 @@
 		possible_disguises[chameleon_item_name] = clothing_path
 
 /obj/item/mod/module/chameleon/on_uninstall(deleting = FALSE)
+	. = ..()
 	if(current_disguise)
 		return_look()
 	possible_disguises = null
@@ -449,7 +453,7 @@
 	mod.righthand_file = initial(current_disguise.righthand_file)
 	mod.worn_icon_state = initial(current_disguise.worn_icon_state)
 	mod.inhand_icon_state = initial(current_disguise.inhand_icon_state)
-	mod.wearer.update_clothing(mod.slot_flags)
+	update_clothing_slots()
 	RegisterSignal(mod, COMSIG_MOD_ACTIVATE, PROC_REF(return_look))
 
 /obj/item/mod/module/chameleon/proc/return_look()
@@ -463,7 +467,7 @@
 	mod.righthand_file = initial(mod.righthand_file)
 	mod.worn_icon_state = null
 	mod.inhand_icon_state = null
-	mod.wearer.update_clothing(mod.slot_flags)
+	update_clothing_slots()
 	current_disguise = null
 	UnregisterSignal(mod, COMSIG_MOD_ACTIVATE)
 
@@ -481,10 +485,12 @@
 	var/old_size
 
 /obj/item/mod/module/plate_compression/on_install()
+	. = ..()
 	old_size = mod.w_class
 	mod.update_weight_class(new_size)
 
 /obj/item/mod/module/plate_compression/on_uninstall(deleting = FALSE)
+	. = ..()
 	mod.update_weight_class(old_size)
 	old_size = null
 	if(!mod.loc)
@@ -528,9 +534,11 @@
 	var/list/traits_to_add = list(TRAIT_SILENT_FOOTSTEPS, TRAIT_UNKNOWN, TRAIT_HEAD_INJURY_BLOCKED)
 
 /obj/item/mod/module/infiltrator/on_install()
+	. = ..()
 	ADD_TRAIT(mod, TRAIT_EXAMINE_SKIP, REF(src))
 
 /obj/item/mod/module/infiltrator/on_uninstall(deleting = FALSE)
+	. = ..()
 	REMOVE_TRAIT(mod, TRAIT_EXAMINE_SKIP, REF(src))
 
 /obj/item/mod/module/infiltrator/on_part_activation()

code/modules/mod/modules/modules_engineering.dm

@@ -62,9 +62,11 @@
 	var/list/active_traits = list(TRAIT_NO_SLIP_WATER, TRAIT_NO_SLIP_ICE, TRAIT_NO_SLIP_SLIDE, TRAIT_NEGATES_GRAVITY)
 
 /obj/item/mod/module/magboot/on_install()
+	. = ..()
 	RegisterSignal(mod, COMSIG_MOD_UPDATE_SPEED, PROC_REF(on_update_speed))
 
-/obj/item/mod/module/magboot/on_uninstall(deleting)
+/obj/item/mod/module/magboot/on_uninstall(deleting = FALSE)
+	. = ..()
 	UnregisterSignal(mod, COMSIG_MOD_UPDATE_SPEED)
 
 /obj/item/mod/module/magboot/on_activation()

code/modules/mod/modules/modules_general.dm

@@ -25,6 +25,7 @@
 	atom_storage.set_locked(STORAGE_FULLY_LOCKED)
 
 /obj/item/mod/module/storage/on_install()
+	. = ..()
 	var/datum/storage/modstorage = mod.create_storage(max_specific_storage = max_w_class, max_total_storage = max_combined_w_class, max_slots = max_items)
 	modstorage.set_real_location(src)
 	modstorage.allow_big_nesting = big_nesting
@@ -34,6 +35,7 @@
 		RegisterSignal(suit, COMSIG_ITEM_PRE_UNEQUIP, PROC_REF(on_suit_unequip))
 
 /obj/item/mod/module/storage/on_uninstall(deleting = FALSE)
+	. = ..()
 	atom_storage.set_locked(STORAGE_FULLY_LOCKED)
 	QDEL_NULL(mod.atom_storage)
 	if(!deleting)
@@ -328,6 +330,7 @@
 	var/former_visor_mask_flags = NONE
 
 /obj/item/mod/module/mouthhole/on_install()
+	. = ..()
 	var/obj/item/clothing/helmet = mod.get_part_from_slot(ITEM_SLOT_HEAD)
 	if(istype(helmet))
 		former_helmet_flags = helmet.flags_cover
@@ -351,6 +354,7 @@
 	return FALSE
 
 /obj/item/mod/module/mouthhole/on_uninstall(deleting = FALSE)
+	. = ..()
 	if(deleting)
 		return
 	var/obj/item/clothing/helmet = mod.get_part_from_slot(ITEM_SLOT_HEAD)
@@ -375,9 +379,11 @@
 	required_slots = list(ITEM_SLOT_BACK|ITEM_SLOT_BELT)
 
 /obj/item/mod/module/emp_shield/on_install()
+	. = ..()
 	mod.AddElement(/datum/element/empprotection, EMP_PROTECT_ALL)
 
 /obj/item/mod/module/emp_shield/on_uninstall(deleting = FALSE)
+	. = ..()
 	mod.RemoveElement(/datum/element/empprotection, EMP_PROTECT_ALL)
 
 /obj/item/mod/module/emp_shield/advanced
@@ -437,7 +443,7 @@
 	active_power_cost = base_power * light_range
 	return ..()
 
-/obj/item/mod/module/flashlight/generate_worn_overlay(mutable_appearance/standing)
+/obj/item/mod/module/flashlight/generate_worn_overlay(obj/item/source, mutable_appearance/standing)
 	. = ..()
 	if(!active)
 		return
@@ -460,7 +466,7 @@
 				balloon_alert(mod.wearer, "too dark!")
 				return
 			set_light_color(value)
-			mod.wearer.update_clothing(mod.slot_flags)
+			update_clothing_slots()
 		if("light_range")
 			set_light_range(clamp(value, min_range, max_range))
 
@@ -594,12 +600,14 @@
 	var/dna = null
 
 /obj/item/mod/module/dna_lock/on_install()
+	. = ..()
 	RegisterSignal(mod, COMSIG_MOD_ACTIVATE, PROC_REF(on_mod_activation))
 	RegisterSignal(mod, COMSIG_MOD_MODULE_REMOVAL, PROC_REF(on_mod_removal))
 	RegisterSignal(mod, COMSIG_ATOM_EMP_ACT, PROC_REF(on_emp))
 	RegisterSignal(mod, COMSIG_ATOM_EMAG_ACT, PROC_REF(on_emag))
 
 /obj/item/mod/module/dna_lock/on_uninstall(deleting = FALSE)
+	. = ..()
 	UnregisterSignal(mod, COMSIG_MOD_ACTIVATE)
 	UnregisterSignal(mod, COMSIG_MOD_MODULE_REMOVAL)
 	UnregisterSignal(mod, COMSIG_ATOM_EMP_ACT)
@@ -665,11 +673,15 @@
 	incompatible_modules = list(/obj/item/mod/module/plasma_stabilizer)
 	required_slots = list(ITEM_SLOT_HEAD)
 
-/obj/item/mod/module/plasma_stabilizer/generate_worn_overlay(mutable_appearance/standing)
+/obj/item/mod/module/plasma_stabilizer/generate_worn_overlay(obj/item/source, mutable_appearance/standing)
+	. = ..()
+	if (!.)
+		return
+
 	var/mutable_appearance/visor_overlay = mod.get_visor_overlay(standing)
 	visor_overlay.appearance_flags |= RESET_COLOR
 	visor_overlay.color = COLOR_VIOLET
-	return list(visor_overlay)
+	. += visor_overlay
 
 /obj/item/mod/module/plasma_stabilizer/on_equip()
 	ADD_TRAIT(mod.wearer, TRAIT_HEAD_ATMOS_SEALED, REF(src))

code/modules/mod/modules/modules_maint.dm

@@ -17,9 +17,11 @@
 	var/step_change = 0.5
 
 /obj/item/mod/module/springlock/on_install()
+	. = ..()
 	mod.activation_step_time *= step_change
 
 /obj/item/mod/module/springlock/on_uninstall(deleting = FALSE)
+	. = ..()
 	mod.activation_step_time /= step_change
 
 /obj/item/mod/module/springlock/on_part_activation()
@@ -149,18 +151,22 @@
 		return
 	SEND_SOUND(mod.wearer, sound('sound/machines/terminal/terminal_off.ogg', volume = 50, channel = CHANNEL_JUKEBOX))
 
-/obj/item/mod/module/visor/rave/generate_worn_overlay(mutable_appearance/standing)
+/obj/item/mod/module/visor/rave/generate_worn_overlay(obj/item/source, mutable_appearance/standing)
+	. = ..()
+	if (!.)
+		return
+
 	var/mutable_appearance/visor_overlay = mod.get_visor_overlay(standing)
 	visor_overlay.appearance_flags |= RESET_COLOR
 	if (!isnull(music_player.active_song_sound))
 		visor_overlay.color = rainbow_order[rave_number]
-	return list(visor_overlay)
+	. += visor_overlay
 
 /obj/item/mod/module/visor/rave/on_active_process(seconds_per_tick)
 	rave_number++
 	if(rave_number > length(rainbow_order))
 		rave_number = 1
-	mod.wearer.update_clothing(mod.slot_flags)
+	update_clothing_slots()
 	rave_screen.update_color(rainbow_order[rave_number])
 
 /obj/item/mod/module/visor/rave/get_configuration()

code/modules/mod/modules/modules_ninja.dm

@@ -93,11 +93,9 @@
 	required_slots = list(ITEM_SLOT_HEAD|ITEM_SLOT_EYES|ITEM_SLOT_MASK)
 
 /obj/item/mod/module/welding/camera_vision/on_part_activation()
-	. = ..()
 	RegisterSignal(mod.wearer, COMSIG_LIVING_CAN_TRACK, PROC_REF(can_track))
 
 /obj/item/mod/module/welding/camera_vision/on_part_deactivation(deleting = FALSE)
-	. = ..()
 	UnregisterSignal(mod.wearer, COMSIG_LIVING_CAN_TRACK)
 
 /obj/item/mod/module/welding/camera_vision/proc/can_track(datum/source, mob/user)
@@ -422,9 +420,11 @@
 	addtimer(CALLBACK(src, PROC_REF(boost_aftereffects), mod.wearer), 7 SECONDS)
 
 /obj/item/mod/module/adrenaline_boost/on_install()
+	. = ..()
 	RegisterSignal(mod, COMSIG_ATOM_ITEM_INTERACTION, PROC_REF(try_boost))
 
 /obj/item/mod/module/adrenaline_boost/on_uninstall(deleting = FALSE)
+	. = ..()
 	UnregisterSignal(mod, COMSIG_ATOM_ITEM_INTERACTION)
 
 /obj/item/mod/module/adrenaline_boost/proc/try_boost(source, mob/user, obj/item/attacking_item)

code/modules/mod/modules/modules_security.dm

@@ -22,6 +22,7 @@
 		guns_typecache = typecacheof(list(/obj/item/gun/ballistic, /obj/item/gun/energy, /obj/item/gun/grenadelauncher, /obj/item/gun/chem, /obj/item/gun/syringe))
 
 /obj/item/mod/module/magnetic_harness/on_install()
+	. = ..()
 	var/obj/item/clothing/suit = mod.get_part_from_slot(ITEM_SLOT_OCLOTHING)
 	if(!istype(suit))
 		return
@@ -29,6 +30,7 @@
 	suit.allowed |= guns_typecache
 
 /obj/item/mod/module/magnetic_harness/on_uninstall(deleting = FALSE)
+	. = ..()
 	if(deleting)
 		return
 	var/obj/item/clothing/suit = mod.get_part_from_slot(ITEM_SLOT_OCLOTHING)
@@ -135,6 +137,7 @@
 		balloon_alert(mod.wearer, "holster full!")
 
 /obj/item/mod/module/holster/on_uninstall(deleting = FALSE)
+	. = ..()
 	if(holstered)
 		holstered.forceMove(drop_location())
 

code/modules/mod/modules/modules_supply.dm

@@ -422,7 +422,7 @@
 		mod.update_speed()
 	traveled_tiles = 0
 
-/obj/item/mod/module/ash_accretion/generate_worn_overlay(mutable_appearance/standing)
+/obj/item/mod/module/ash_accretion/generate_worn_overlay(obj/item/source, mutable_appearance/standing)
 	overlay_state_inactive = "[initial(overlay_state_inactive)]-[mod.skin]"
 	return ..()
 

code/modules/mod/modules/modules_timeline.dm

@@ -20,10 +20,12 @@
 	var/true_owner_ckey
 
 /obj/item/mod/module/eradication_lock/on_install()
+	. = ..()
 	RegisterSignal(mod, COMSIG_MOD_ACTIVATE, PROC_REF(on_mod_activation))
 	RegisterSignal(mod, COMSIG_MOD_MODULE_REMOVAL, PROC_REF(on_mod_removal))
 
 /obj/item/mod/module/eradication_lock/on_uninstall(deleting = FALSE)
+	. = ..()
 	UnregisterSignal(mod, COMSIG_MOD_ACTIVATE)
 	UnregisterSignal(mod, COMSIG_MOD_MODULE_REMOVAL)
 
@@ -228,6 +230,7 @@
 	INVOKE_ASYNC(chrono_beam, TYPE_PROC_REF(/obj/projectile, fire))
 
 /obj/item/mod/module/tem/on_uninstall(deleting = FALSE)
+	. = ..()
 	if(!field)
 		return
 	field_disconnect(field)