You can smuggle smuggler's satchels to a future shift (#19838)

* Hidden Smuggler Satchels hidden beneath the station now persist between rounds, though there's no assurances of WHEN they'll appear next and only one will ever appear in the round.

NOTE THAT THIS PULL INTRODUCES A CRITICAL BUG, DO NOT MERGE *JUST* THIS PR, AWAIT THE FOLLOWUP

* Finishes up satchel persistence.

Satchels require at least 20 saved bags before any will start spawning.

the var persistence_replacement can be set to a path to replace a very high risk item with a lower risk look alike. This is currently done with the nuke disk, the wizards spellbook, and the uplink implant

* DESIGNATED.
REMIE.
PULL.

code/controllers/subsystem/persistence.dm

@@ -0,0 +1,66 @@
+var/datum/subsystem/persistence/SSpersistence
+
+/datum/subsystem/persistence
+	name = "Persistence"
+	init_order = -100
+	flags = SS_NO_FIRE
+	var/savefile/secret_satchels
+	var/list/satchel_blacklist 		= list() //this is a typecache
+	var/list/new_secret_satchels 	= list() //these are objects
+	var/list/old_secret_satchels 	= list() //these are just vars
+
+/datum/subsystem/persistence/New()
+	NEW_SS_GLOBAL(SSpersistence)
+
+/datum/subsystem/persistence/Initialize()
+	PlaceSecretSatchel()
+	..()
+
+/datum/subsystem/persistence/proc/CollectData()
+	CollectSecretSatchels()
+
+/datum/subsystem/persistence/proc/PlaceSecretSatchel()
+	var/list/satchels = list()
+	secret_satchels = new /savefile("data/npc_saves/SecretSatchels_[MAP_NAME].sav")
+	satchel_blacklist = typecacheof(list(/obj/item/stack/tile/plasteel, /obj/item/weapon/crowbar))
+
+	secret_satchels >> satchels
+	if(!satchels.len || satchels.len < 20) //guards against low drop pools assuring that one player can reliably find his own gear.
+		return
+
+	var/list/chosen_satchel = pick_n_take(satchels)
+	old_secret_satchels = satchels
+	secret_satchels << old_secret_satchels
+	if(chosen_satchel.len != 3) //Malformed
+		return
+
+	var/path = text2path(chosen_satchel[3]) //If the item no longer exist, this returns null
+	if(!path)
+		return
+
+	var/obj/item/weapon/storage/backpack/satchel/flat/F = new()
+	F.x = chosen_satchel[1]
+	F.y = chosen_satchel[2]
+	F.z = ZLEVEL_STATION
+	if(istype(F.loc,/turf/open/floor) && !istype(F.loc,/turf/open/floor/plating/))
+		F.hide(1)
+	new path(F)
+
+/datum/subsystem/persistence/proc/CollectSecretSatchels()
+	for(var/A in new_secret_satchels)
+		var/obj/item/weapon/storage/backpack/satchel/flat/F = A
+		if(qdeleted(F) || F.z != ZLEVEL_STATION || F.invisibility != INVISIBILITY_MAXIMUM)
+			continue
+		var/list/savable_obj = list()
+		for(var/obj/O in F)
+			if(is_type_in_typecache(O, satchel_blacklist) || O.admin_spawned)
+				continue
+			if(O.persistence_replacement)
+				savable_obj += O.persistence_replacement
+			else
+				savable_obj += O.type
+		if(savable_obj.len < 1)
+			continue
+		old_secret_satchels.len += 1
+		old_secret_satchels[old_secret_satchels.len] = list(F.x, F.y, "[pick(savable_obj)]")
+	secret_satchels << old_secret_satchels

code/controllers/subsystem/ticker.dm

@@ -451,6 +451,8 @@ var/datum/subsystem/ticker/ticker
 			dellog += "Failures : [SSgarbage.didntgc[path]] \n"
 		world.log << dellog
 
+	//Collects persistence features
+	SSpersistence.CollectData()
 	return 1
 
 /datum/subsystem/ticker/proc/send_tip_of_the_round()