Experiment with replacing weakrefs in AI blackboard with deleting signals, ideally making it easier to work with and harder to cause hard deletes (#74791)

## About The Pull Request

Replaces weakref usage in AI blackboards with deleting signals

All blackboard var setting must go through setters rather than directly

## Why It's Good For The Game

This both makes it a ton easier to develop AI for, and also makes it
harder for hard deletes to sneak in, as has been seen with recent 515
prs showing hard deletes in AI blackboards

(To quantify "making it easier to develop AI", I found multiple bugs in
existing AI code due to the usage of weakrefs.)

I'm looking for `@Jacquerel` `@tralezab` 's opinions on the matter, also
maybe `@LemonInTheDark` if they're interested

## Changelog

🆑 Melbert
refactor: Mob ai refactored once again
/🆑

code/datums/components/ai_retaliate_advanced.dm

@@ -25,9 +25,6 @@
 
 	if (!victim.ai_controller)
 		return
-	var/list/enemy_refs = victim.ai_controller.blackboard[BB_BASIC_MOB_RETALIATE_LIST]
-	if (!enemy_refs)
-		enemy_refs = list()
-	enemy_refs |= WEAKREF(attacker)
-	victim.ai_controller.blackboard[BB_BASIC_MOB_RETALIATE_LIST] = enemy_refs
+
+	victim.ai_controller.insert_blackboard_key_lazylist(BB_BASIC_MOB_RETALIATE_LIST, attacker)
 	post_retaliate_callback?.InvokeAsync(attacker)

code/datums/components/pet_commands/fetch.dm

@@ -39,7 +39,7 @@
 	var/list/blackboard = parent.ai_controller.blackboard
 	if (!trigger_on_throw && !blackboard[BB_ACTIVE_PET_COMMAND])
 		return // We don't have a command and we only listen to commands
-	if (blackboard[BB_ACTIVE_PET_COMMAND] && blackboard[BB_ACTIVE_PET_COMMAND] != WEAKREF(src))
+	if (blackboard[BB_ACTIVE_PET_COMMAND] && blackboard[BB_ACTIVE_PET_COMMAND] != src)
 		return // We have a command and it's not this one
 	if (blackboard[BB_CURRENT_PET_TARGET] || blackboard[BB_FETCH_DELIVER_TO])
 		return // We're already very fetching
@@ -49,7 +49,7 @@
 	var/obj/item/thrown_thing = thrower.get_active_held_item()
 	if (!isitem(thrown_thing))
 		return
-	if (blackboard[BB_FETCH_IGNORE_LIST] && blackboard[BB_FETCH_IGNORE_LIST][WEAKREF(thrown_thing)])
+	if (blackboard[BB_FETCH_IGNORE_LIST]?[thrown_thing])
 		return // We're ignoring it already
 
 	RegisterSignal(thrown_thing, COMSIG_MOVABLE_THROW_LANDED, PROC_REF(listen_throw_land))
@@ -69,7 +69,7 @@
 
 	try_activate_command(throwing_datum.thrower)
 	set_command_target(parent, thrown_thing)
-	parent.ai_controller.blackboard[BB_FETCH_DELIVER_TO] = WEAKREF(throwing_datum.thrower)
+	parent.ai_controller.set_blackboard_key(BB_FETCH_DELIVER_TO, throwing_datum.thrower)
 
 // Don't try and fetch turfs or anchored objects if someone points at them
 /datum/pet_command/point_targetting/fetch/look_for_target(mob/living/pointing_friend, obj/item/pointed_atom)
@@ -82,16 +82,15 @@
 		return FALSE
 
 	var/mob/living/parent = weak_parent.resolve()
-	parent.ai_controller.blackboard[BB_FETCH_DELIVER_TO] = WEAKREF(pointing_friend)
+	parent.ai_controller.set_blackboard_key(BB_FETCH_DELIVER_TO, pointing_friend)
 
 // Finally, plan our actions
 /datum/pet_command/point_targetting/fetch/execute_action(datum/ai_controller/controller)
 	controller.queue_behavior(/datum/ai_behavior/forget_failed_fetches)
 
-	var/datum/weakref/weak_target = controller.blackboard[BB_CURRENT_PET_TARGET]
-	var/atom/target = weak_target?.resolve()
+	var/atom/target = controller.blackboard[BB_CURRENT_PET_TARGET]
 	// We got something to fetch so go fetch it
-	if (target)
+	if (!QDELETED(target))
 		if (get_dist(controller.pawn, target) > 1) // We're not there yet
 			controller.queue_behavior(/datum/ai_behavior/fetch_seek, BB_CURRENT_PET_TARGET, BB_FETCH_DELIVER_TO)
 			return SUBTREE_RETURN_FINISH_PLANNING
@@ -99,16 +98,14 @@
 		controller.queue_behavior(/datum/ai_behavior/pick_up_item, BB_CURRENT_PET_TARGET, BB_SIMPLE_CARRY_ITEM)
 		return SUBTREE_RETURN_FINISH_PLANNING
 
-	var/datum/weakref/carried_ref = controller.blackboard[BB_SIMPLE_CARRY_ITEM]
-	var/obj/item/carried_item = carried_ref?.resolve()
-	if (!carried_item)
+	var/obj/item/carried_item = controller.blackboard[BB_SIMPLE_CARRY_ITEM]
+	if (QDELETED(carried_item))
 		return
 
-	var/datum/weakref/delivery_ref = controller.blackboard[BB_FETCH_DELIVER_TO]
-	var/atom/delivery_target = delivery_ref?.resolve()
-	if (!delivery_target || !can_see(controller.pawn, delivery_target, sense_radius))
+	var/atom/delivery_target = controller.blackboard[BB_FETCH_DELIVER_TO]
+	if (QDELETED(delivery_target) || !can_see(controller.pawn, delivery_target, sense_radius))
 		// We don't know where to return this to so we're just going to keep it
-		controller.blackboard[BB_ACTIVE_PET_COMMAND] = null
+		controller.clear_blackboard_key(BB_ACTIVE_PET_COMMAND)
 		return
 
 	// We got something to deliver and someone to deliver it to

code/datums/components/pet_commands/obeys_commands.dm

@@ -57,10 +57,7 @@
 
 	if (IS_DEAD_OR_INCAP(source))
 		return
-	if (!source.ai_controller)
-		return
-	var/list/friends_list = source.ai_controller.blackboard[BB_FRIENDS_LIST]
-	if (!friends_list || !friends_list[WEAKREF(user)])
+	if (!(user in source.ai_controller?.blackboard[BB_FRIENDS_LIST]))
 		return
 	examine_list += span_notice("[source.p_they(capitalized = TRUE)] seem[source.p_s()] happy to see you!")
 
@@ -71,10 +68,7 @@
 	var/mob/living/living_parent = parent
 	if (IS_DEAD_OR_INCAP(living_parent))
 		return
-	if (!living_parent.ai_controller)
-		return
-	var/list/friends_list = living_parent.ai_controller.blackboard[BB_FRIENDS_LIST]
-	if (!friends_list || !friends_list[WEAKREF(clicker)])
+	if (!(clicker in living_parent.ai_controller?.blackboard[BB_FRIENDS_LIST]))
 		return // Not our friend, can't boss us around
 
 	INVOKE_ASYNC(src, PROC_REF(display_radial_menu), clicker)

code/datums/components/pet_commands/pet_command.dm

@@ -68,7 +68,7 @@
 		return
 	if (IS_DEAD_OR_INCAP(parent)) // Probably can't hear them if we're dead
 		return
-	if (parent.ai_controller.blackboard[BB_ACTIVE_PET_COMMAND] == WEAKREF(src)) // We're already doing it
+	if (parent.ai_controller.blackboard[BB_ACTIVE_PET_COMMAND] == src) // We're already doing it
 		return
 	set_command_active(parent, commander)
 
@@ -77,13 +77,13 @@
 	set_command_target(parent, null)
 
 	parent.ai_controller.CancelActions() // Stop whatever you're doing and do this instead
-	parent.ai_controller.blackboard[BB_ACTIVE_PET_COMMAND] = WEAKREF(src)
+	parent.ai_controller.set_blackboard_key(BB_ACTIVE_PET_COMMAND, src)
 	if (command_feedback)
 		parent.balloon_alert_to_viewers("[command_feedback]") // If we get a nicer runechat way to do this, refactor this
 
 /// Store the target for the AI blackboard
 /datum/pet_command/proc/set_command_target(mob/living/parent, atom/target)
-	parent.ai_controller.blackboard[BB_CURRENT_PET_TARGET] = WEAKREF(target)
+	parent.ai_controller.set_blackboard_key(BB_CURRENT_PET_TARGET, target)
 
 /// Provide information about how to display this command in a radial menu
 /datum/pet_command/proc/provide_radial_data()
@@ -137,9 +137,9 @@
 		return FALSE
 	if (IS_DEAD_OR_INCAP(parent))
 		return FALSE
-	if (parent.ai_controller.blackboard[BB_ACTIVE_PET_COMMAND] != WEAKREF(src)) // We're not listening right now
+	if (parent.ai_controller.blackboard[BB_ACTIVE_PET_COMMAND] != src) // We're not listening right now
 		return FALSE
-	if (parent.ai_controller.blackboard[BB_CURRENT_PET_TARGET] == WEAKREF(pointed_atom)) // That's already our target
+	if (parent.ai_controller.blackboard[BB_CURRENT_PET_TARGET] == pointed_atom) // That's already our target
 		return FALSE
 	if (!can_see(parent, pointed_atom, sense_radius))
 		return FALSE

code/datums/components/pet_commands/pet_commands_basic.dm

@@ -28,7 +28,7 @@
 	command_feedback = "relaxes"
 
 /datum/pet_command/free/execute_action(datum/ai_controller/controller)
-	controller.blackboard[BB_ACTIVE_PET_COMMAND] = null
+	controller.clear_blackboard_key(BB_ACTIVE_PET_COMMAND)
 	return // Just move on to the next planning subtree.
 
 /**
@@ -87,7 +87,7 @@
 	// If we get past this point someone has finally added a non-binary dog
 
 /datum/pet_command/good_boy/execute_action(datum/ai_controller/controller)
-	controller.blackboard[BB_ACTIVE_PET_COMMAND] = null
+	controller.clear_blackboard_key(BB_ACTIVE_PET_COMMAND)
 	var/mob/living/parent = weak_parent.resolve()
 	if (!parent)
 		return SUBTREE_RETURN_FINISH_PLANNING