'lolman? did you test your code?'

no i did not ms. kevinz

code/datums/ductnet.dm

@@ -0,0 +1,60 @@
+/datum/ductnet
+	var/list/suppliers = list()
+	var/list/demanders = list()
+	var/list/obj/machinery/duct/ducts = list()
+
+	var/capacity
+
+/datum/ductnet/proc/add_duct(obj/machinery/duct/D)
+	if(!D || D in ducts)
+		return
+	ducts += D
+	D.duct = src
+
+/datum/ductnet/proc/remove_duct(obj/machinery/duct/ducting)
+	destroy_network(FALSE)
+	for(var/A in ducting.neighbours)
+		var/obj/machinery/duct/D = A
+		D.attempt_connect() //we destroyed the network, so now we tell the disconnected ducts neighbours they can start making a new ductnet
+	qdel(src)
+
+/datum/ductnet/proc/add_plumber(datum/component/plumbing/P, dir)
+	if(!P.can_add(src, dir))
+		return
+	P.ducts[num2text(dir)] = src
+	if(dir & P.supply_connects)
+		suppliers += P
+	else if(dir & P.demand_connects)
+		demanders += P
+
+/datum/ductnet/proc/remove_plumber(datum/component/plumbing/P)
+	suppliers.Remove(P) //we're probably only in one of these, but Remove() is inherently sane so this is fine
+	demanders.Remove(P)
+
+	for(var/dir in P.ducts)
+		if(P.ducts[dir] == src)
+			P.ducts -= dir
+
+/datum/ductnet/proc/assimilate(datum/ductnet/D)
+	ducts.Add(D.ducts)
+	suppliers.Add(D.suppliers)
+	demanders.Add(D.demanders)
+	for(var/A in D.suppliers + D.demanders)
+		var/datum/component/plumbing/P = A
+		for(var/s in P.ducts)
+			if(P.ducts[s] != D)
+				continue
+			P.ducts[s] = src  //all your ducts are belong to us
+	for(var/A in D.ducts)
+		var/obj/machinery/duct/M = A
+		M.duct = src //forget your old master
+	qdel(D)
+
+/datum/ductnet/proc/destroy_network(delete=TRUE)
+	for(var/A in suppliers + demanders)
+		remove_plumber(A)
+	for(var/A in ducts)
+		var/obj/machinery/duct/D = A
+		D.duct = null
+	if(delete) //I don't want code to run with qdeleted objects because that can never be good, so keep this in-case the ductnet has some business left to attend to before commiting suicide
+		qdel(src)