Adds true observing -- letting you see what your target sees (#24855)

* bring it back now y'all

* adds a bunch of other changes

* pretty much works at this point

* grep

* Fixes some bugs, still chasing some down

* Add observers to recursive mob check, ensuring they can see messages from their orbitted atom

* tidy some things up

* resolve

* remove unnecessary checks

* Address todos, minor cleanups

* oh dear

* initial testing

* Fix some vulnerabilities (oops)

* Fix some other bugs from testing

* ci fixes

* Add some contingencies against clicking things you shouldn't

* fix some noted bugs

* Add observe to admin jump, improve messaging

* add a few more fixes that should mostly address some runtimes

* oh this wasn't really great

* one last thing

* Fix suit inventory problem

* Remove merge artifact

* Add some missing parens

* Prevents you from observing other ghosts, and should fix the getting stuck outside of your body issue.

* we love testing

* adds to player panel

* Fix more bugs with observers getting stuck outside of their body

* cleans up player panel, verb offerings

* shit

* Update code/_onclick/hud/alert.dm

welp

Co-authored-by: GDN <96800819+GDNgit@users.noreply.github.com>
Signed-off-by: Luc <89928798+lewcc@users.noreply.github.com>

* Fixes some targeting issues

* Fixes targeting on aobserve

* Fix some weird storage bugs

* clean up some doulbed up follow links

* Update code/modules/admin/player_panel.dm

Signed-off-by: Luc <89928798+lewcc@users.noreply.github.com>

* Adds some checks for ghost observe

* Remove mentor debug log

* ahhhhhhhhh that'll do it

* Cleans up some additional checks that were not quite what they should have been

* better logging, too

* mochi review

* one more thing

* Gets robot huds mostly working

* hopefully fix folks not getting observe

* Fix order of operations causing a runtime on qdeleting

* Remove some unnecessary stack traces

* Apply suggestions from code review

Co-authored-by: 1080pCat <96908085+1080pCat@users.noreply.github.com>
Signed-off-by: Luc <89928798+lewcc@users.noreply.github.com>

* Fix bug with items in your inventory disappearing on changing HUD modes

* Fix some bugs with the observe verbs

* possibly fix nullspace issues

* funny review

* missed one

---------

Signed-off-by: Luc <89928798+lewcc@users.noreply.github.com>
Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: GDN <96800819+GDNgit@users.noreply.github.com>
Co-authored-by: S34N <12197162+S34NW@users.noreply.github.com>
Co-authored-by: 1080pCat <96908085+1080pCat@users.noreply.github.com>

code/__DEFINES/admin_defines.dm

@@ -46,12 +46,14 @@
 
 #define R_HOST			((1<<18)-1) //17 bit bitmask, update me if we ever add more admin permissions. Sum of all permissions to allow easy setting.
 
+
 #define ADMIN_QUE(user,display) "<a href='byond://?_src_=holder;adminmoreinfo=[user.UID()]'>[display]</a>"
 #define ADMIN_FLW(user,display) "<a href='byond://?_src_=holder;adminplayerobservefollow=[user.UID()]'>[display]</a>"
 #define ADMIN_PP(user,display) "<a href='byond://?_src_=holder;adminplayeropts=[user.UID()]'>[display]</a>"
 #define ADMIN_VV(atom,display) "<a href='byond://?_src_=vars;Vars=[atom.UID()]'>[display]</a>"
 #define ADMIN_SM(user,display) "<a href='byond://?_src_=holder;subtlemessage=[user.UID()]'>[display]</a>"
 #define ADMIN_TP(user,display) "<a href='byond://?_src_=holder;traitor=[user.UID()]'>[display]</a>"
+#define ADMIN_OBS(user, display) "<a href='byond://?_src_=holder;adminobserve=[user.UID()]'>[display]</a>"
 #define ADMIN_ALERT(user, display) "<a href='byond://?_src_=holder;adminalert=[user.UID()]'>[display]</a>"
 #define ADMIN_BSA(user,display) "<a href='byond://?_src_=holder;BlueSpaceArtillery=[user.UID()]'>[display]</a>"
 #define ADMIN_CENTCOM_REPLY(user,display) "<a href='byond://?_src_=holder;CentcommReply=[user.UID()]'>[display]</a>"

code/__DEFINES/dcs/signals.dm

@@ -181,6 +181,8 @@
 #define COMSIG_ATOM_ORBIT_BEGIN "atom_orbit_begin"
 ///called when an atom stops orbiting another atom: (atom)
 #define COMSIG_ATOM_ORBIT_STOP "atom_orbit_stop"
+/// called on an atom who has stopped orbiting another atom (atom/orbiter, atom/formerly_orbited)
+#define COMSIG_ATOM_ORBITER_STOP "atom_orbiter_stop"
 ///from base of atom/hitby(atom/movable/AM, skipcatch, hitpush, blocked, datum/thrownthing/throwingdatum)
 #define COMSIG_ATOM_HITBY "atom_hitby"
 /// Called when an atom is sharpened or dulled.
@@ -945,11 +947,26 @@
 ///from base of datum/action/proc/Trigger(): (datum/action)
 #define COMSIG_ACTION_TRIGGER "action_trigger"
 	#define COMPONENT_ACTION_BLOCK_TRIGGER (1<<0)
+/// From /datum/action/Grant(): (mob/grant_to)
+#define COMSIG_ACTION_GRANTED "action_grant"
+/// From /datum/action/Grant(): (datum/action)
+#define COMSIG_MOB_GRANTED_ACTION "mob_action_grant"
+/// From /datum/action/Remove(): (mob/removed_from)
+#define COMSIG_ACTION_REMOVED "action_removed"
+/// From /datum/action/Remove(): (datum/action)
+#define COMSIG_MOB_REMOVED_ACTION "mob_action_removed"
 
 // Note that this is only defined for actions because this could be a good bit expensive otherwise
 /// From base of /atom/movable/screen/movable/action_button/MouseWheel(src, delta_x, delta_y, location, control, params)
 #define COMSIG_ACTION_SCROLLED "action_scrolled"
 
+// ghost signals
+
+/// from observer_base/do_observe(): (mob/now_followed)
+#define COMSIG_GHOST_START_OBSERVING "ghost_start_observing"
+/// from observer_base/do_observe(): (mob/no_longer_following)
+#define COMSIG_GHOST_STOP_OBSERVING "ghost_stop_observing"
+
 //Xenobio hotkeys
 
 ///from slime CtrlClickOn(): (/mob)

code/__HELPERS/game.dm

@@ -164,6 +164,8 @@
 			if(sight_check && !isInSight(A, O))
 				continue
 			L |= M
+			for(var/mob/dead/observer/ghost in M.observers)
+				L |= ghost
 			//log_world("[recursion_limit] = [M] - [get_turf(M)] - ([M.x], [M.y], [M.z])")
 
 		if(isobj(A) || ismob(A))

code/__HELPERS/lists.dm

@@ -676,6 +676,7 @@
 #define UNSETEMPTY(L) if(L && !length(L)) L = null
 #define LAZYREMOVE(L, I) if(L) { L -= I; if(!length(L)) { L = null; } }
 #define LAZYADD(L, I) if(!L) { L = list(); } L += I;
+/// Add an item to the list if not already present, if the list is null it will initialize it
 #define LAZYOR(L, I) if(!L) { L = list(); } L |= I;
 /// Adds I to L, initializing L if necessary, if I is not already in L
 #define LAZYDISTINCTADD(L, I) if(!L) { L = list(); } L |= I;

code/__HELPERS/mob_helpers.dm

@@ -554,7 +554,7 @@ GLOBAL_LIST_EMPTY(do_after_once_tracker)
 	to_chat(user, "Name = <b>[M.name]</b>; Real_name = [M.real_name]; Mind_name = [M.mind?"[M.mind.name]":""]; Key = <b>[M.key]</b>;")
 	to_chat(user, "Location = [location_description];")
 	to_chat(user, "[special_role_description]")
-	to_chat(user, "(<a href='byond://?src=[usr.UID()];priv_msg=[M.client?.ckey]'>PM</a>) ([ADMIN_PP(M,"PP")]) ([ADMIN_VV(M,"VV")]) ([ADMIN_TP(M,"TP")]) ([ADMIN_SM(M,"SM")]) ([ADMIN_FLW(M,"FLW")])")
+	to_chat(user, "(<a href='byond://?src=[usr.UID()];priv_msg=[M.client?.ckey]'>PM</a>) ([ADMIN_PP(M,"PP")]) ([ADMIN_VV(M,"VV")]) ([ADMIN_TP(M,"TP")]) ([ADMIN_SM(M,"SM")]) ([ADMIN_FLW(M,"FLW")]) ([ADMIN_OBS(M, "OBS")])")
 
 // Gets the first mob contained in an atom, and warns the user if there's not exactly one
 /proc/get_mob_in_atom_with_warning(atom/A, mob/user = usr)

code/__HELPERS/trait_helpers.dm

@@ -235,6 +235,10 @@ Remember to update _globalvars/traits.dm if you're adding/removing/renaming trai
 #define TRAIT_SLEIGHT_OF_HAND "sleight_of_hand"
 #define TRAIT_KNOWS_COOKING_RECIPES "knows_cooking_recipes"
 
+/// used for dead mobs that are observing, but should not be afforded all the same platitudes as full ghosts.
+/// This is a mind trait because ghosts can be frequently deleted and we want to be sure this sticks.
+#define TRAIT_MENTOR_OBSERVING "mentor_observe"
+
 //***** ITEM AND MOB TRAITS *****//
 /// Show what machine/door wires do when held.
 #define TRAIT_SHOW_WIRE_INFO "show_wire_info"
@@ -321,6 +325,8 @@ Remember to update _globalvars/traits.dm if you're adding/removing/renaming trai
 #define HOLO_CIGAR "holo_cigar"
 #define GLADIATOR "gladiator"
 #define PULSEDEMON_TRAIT "pulse_demon"
+/// Mentor observing
+#define MENTOR_OBSERVING "mobserving"
 
 //quirk traits
 #define TRAIT_ALCOHOL_TOLERANCE	"alcohol_tolerance"

code/_onclick/hud/action_button.dm

@@ -16,6 +16,8 @@
 	var/id
 	/// UID of the last thing we hovered over. Used for managing action button dragging.
 	var/last_hovered_ref
+	/// Whether or not this should be shown to observers
+	var/shown_to_observers = FALSE
 	/// Whether or not this button is locked, preventing it from being dragged.
 	var/locked = FALSE
 
@@ -32,8 +34,14 @@
 	return ..()
 
 /atom/movable/screen/movable/action_button/proc/can_use(mob/user)
+	if(isobserver(user))
+		var/mob/dead/observer/dead_mob = user
+		if(dead_mob.mob_observed) // Observers can only click on action buttons if they're not observing something
+			return FALSE
 	if(!linked_action)
 		return TRUE
+	if(linked_action.owner != user)
+		return FALSE
 	return !isnull(linked_action.viewers[user.hud_used])
 
 // Entered and Exited won't fire while you're dragging something, because you're still "holding" it
@@ -60,7 +68,8 @@
 		last_hovered.MouseExited(over_location, over_control, params)
 		closeToolTip(usr)
 	last_hovered_ref = UID(over_object)
-	over_object.MouseEntered(over_location, over_control, params)
+	if(!isnull(over_object))
+		over_object.MouseEntered(over_location, over_control, params)
 
 /atom/movable/screen/movable/action_button/MouseDrop(over_object)
 	last_hovered_ref = null
@@ -113,6 +122,8 @@
 	animate(src, transform = matrix(), time = 0.4 SECONDS, alpha = 255)
 
 /atom/movable/screen/movable/action_button/Click(location, control, params)
+	if(!can_use(usr))
+		return FALSE
 	var/list/modifiers = params2list(params)
 	if(modifiers["ctrl"] && modifiers["shift"])
 		INVOKE_ASYNC(src, PROC_REF(set_to_keybind), usr)
@@ -578,4 +589,47 @@ GLOBAL_LIST_INIT(palette_removed_matrix, list(1.4,0,0,0, 0.7,0.4,0,0, 0.4,0,0.6,
 			button = action.viewers[src]
 		position_action(button, button.location)
 
+
+/**
+ * Show (most) of the another mob's action buttons to this mob
+ *
+ * Used for observers viewing another mob's screen
+ */
+/mob/proc/show_other_mob_action_buttons(mob/take_from)
+	if(!hud_used || !client)
+		return
+
+	for(var/datum/action/action as anything in take_from.actions)
+		if(!action.show_to_observers)
+			continue
+		action.GiveAction(src)
+	RegisterSignal(take_from, COMSIG_MOB_GRANTED_ACTION, PROC_REF(on_observing_action_granted), override = TRUE)
+	RegisterSignal(take_from, COMSIG_MOB_REMOVED_ACTION, PROC_REF(on_observing_action_removed), override = TRUE)
+
+/**
+ * Hide another mob's action buttons from this mob
+ *
+ * Used for observers viewing another mob's screen
+ */
+/mob/proc/hide_other_mob_action_buttons(mob/take_from)
+	for(var/datum/action/action as anything in take_from.actions)
+		action.HideFrom(src)
+	UnregisterSignal(take_from, list(COMSIG_MOB_GRANTED_ACTION, COMSIG_MOB_REMOVED_ACTION))
+
+/// Signal proc for [COMSIG_MOB_GRANTED_ACTION] - If we're viewing another mob's action buttons,
+/// we need to update with any newly added buttons granted to the mob.
+/mob/proc/on_observing_action_granted(mob/living/source, datum/action/action)
+	SIGNAL_HANDLER  // COMSIG_MOB_GRANTED_ACTION
+
+	if(!action.show_to_observers)
+		return
+	action.GiveAction(src)
+
+/// Signal proc for [COMSIG_MOB_REMOVED_ACTION] - If we're viewing another mob's action buttons,
+/// we need to update with any removed buttons from the mob.
+/mob/proc/on_observing_action_removed(mob/living/source, datum/action/action)
+	SIGNAL_HANDLER  // COMSIG_MOB_REMOVED_ACTION
+
+	action.HideFrom(src)
+
 #undef AB_MAX_COLUMNS

code/_onclick/hud/ai_hud.dm

@@ -1,20 +1,27 @@
 /atom/movable/screen/ai
 	icon = 'icons/mob/screen_ai.dmi'
 
+/atom/movable/screen/ai/Click()
+	if(isobserver(usr) || usr.incapacitated())
+		return TRUE
+
 /atom/movable/screen/ai/aicore
 	name = "AI core"
 	icon_state = "ai_core"
 
 /atom/movable/screen/ai/aicore/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.view_core()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.view_core()
 
 /atom/movable/screen/ai/camera_list
 	name = "Show Camera List"
 	icon_state = "camera"
 
 /atom/movable/screen/ai/camera_list/Click()
+	if(..())
+		return
 	var/mob/living/silicon/ai/AI = usr
 	var/camera = tgui_input_list(AI, "Choose which camera you want to view", "Cameras", AI.get_camera_list())
 	AI.ai_camera_list(camera)
@@ -24,53 +31,60 @@
 	icon_state = "track"
 
 /atom/movable/screen/ai/camera_track/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		var/target_name = tgui_input_list(AI, "Choose a target you want to track", "Tracking", AI.trackable_mobs())
-		if(target_name)
-			AI.ai_camera_track(target_name)
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	var/target_name = tgui_input_list(AI, "Choose a target you want to track", "Tracking", AI.trackable_mobs())
+	if(target_name)
+		AI.ai_camera_track(target_name)
 
 /atom/movable/screen/ai/camera_light
 	name = "Toggle Camera Light"
 	icon_state = "camera_light"
 
 /atom/movable/screen/ai/camera_light/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.toggle_camera_light()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.toggle_camera_light()
 
 /atom/movable/screen/ai/crew_monitor
 	name = "Crew Monitoring Console"
 	icon_state = "crew_monitor"
 
 /atom/movable/screen/ai/crew_monitor/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.subsystem_crew_monitor()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.subsystem_crew_monitor()
 
 /atom/movable/screen/ai/crew_manifest
 	name = "Crew Manifest"
 	icon_state = "manifest"
 
 /atom/movable/screen/ai/crew_manifest/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.ai_roster()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.ai_roster()
 
 /atom/movable/screen/ai/alerts
 	name = "Show Alerts"
 	icon_state = "alerts"
 
 /atom/movable/screen/ai/alerts/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.ai_alerts()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.ai_alerts()
 
 /atom/movable/screen/ai/announcement
 	name = "Make Announcement"
 	icon_state = "announcement"
 
 /atom/movable/screen/ai/announcement/Click()
+	if(..())
+		return
 	var/mob/living/silicon/ai/AI = usr
 	AI.announcement()
 
@@ -79,15 +93,18 @@
 	icon_state = "call_shuttle"
 
 /atom/movable/screen/ai/call_shuttle/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.ai_call_shuttle()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.ai_call_shuttle()
 
 /atom/movable/screen/ai/state_laws
 	name = "Law Manager"
 	icon_state = "state_laws"
 
 /atom/movable/screen/ai/state_laws/Click()
+	if(..())
+		return
 	if(isAI(usr))
 		var/mob/living/silicon/ai/AI = usr
 		AI.subsystem_law_manager()
@@ -97,42 +114,48 @@
 	icon_state = "pda_send"
 
 /atom/movable/screen/ai/pda_msg_send/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.aiPDA.cmd_send_pdamesg()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.aiPDA.cmd_send_pdamesg()
 
 /atom/movable/screen/ai/pda_msg_show
 	name = "PDA - Show Message Log"
 	icon_state = "pda_receive"
 
 /atom/movable/screen/ai/pda_msg_show/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.aiPDA.cmd_show_message_log()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.aiPDA.cmd_show_message_log()
 
 /atom/movable/screen/ai/image_take
 	name = "Take Image"
 	icon_state = "take_picture"
 
 /atom/movable/screen/ai/image_take/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.aiCamera.toggle_camera_mode()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.aiCamera.toggle_camera_mode()
 
 /atom/movable/screen/ai/image_view
 	name = "View Images"
 	icon_state = "view_images"
 
 /atom/movable/screen/ai/image_view/Click()
-	if(isAI(usr))
-		var/mob/living/silicon/ai/AI = usr
-		AI.aiCamera.viewpictures()
+	if(..())
+		return
+	var/mob/living/silicon/ai/AI = usr
+	AI.aiCamera.viewpictures()
 
 /atom/movable/screen/ai/sensors
 	name = "Toggle Sensor Augmentation"
 	icon_state = "ai_sensor"
 
 /atom/movable/screen/ai/sensors/Click()
+	if(..())
+		return
 	if(isAI(usr))
 		var/mob/living/silicon/ai/AI = usr
 		AI.sensor_mode()

code/_onclick/hud/alert.dm

@@ -48,6 +48,8 @@
 		if(override)
 			alert.timeout = null
 
+		alert.attach_owner(src)
+
 	if(icon_override)
 		alert.icon = icon_override
 
@@ -100,10 +102,50 @@
 	name = "Alert"
 	desc = "Something seems to have gone wrong with this alert, so report this bug please"
 	mouse_opacity = MOUSE_OPACITY_ICON
-	var/timeout = 0 //If set to a number, this alert will clear itself after that many deciseconds
+	/// How long before this alert automatically clears itself (in deciseconds). If zero, remains until cleared.
+	var/timeout = 0
+	/// Some alerts may have different icon states based on severity, this adjusts that.
 	var/severity = 0
+	/// Tool-tip for the alert.
 	var/alerttooltipstyle = ""
-	var/override_alerts = FALSE //If it is overriding other alerts of the same type
+	/// If true, this should override any other alerts of the same type thrown.
+	var/override_alerts = FALSE
+	/// The mob that this alert was originally thrown to.
+	var/mob/owner
+
+/atom/movable/screen/alert/proc/attach_owner(mob/new_owner)
+	owner = new_owner
+	RegisterSignal(owner, COMSIG_PARENT_QDELETING, PROC_REF(remove_owner))
+
+/atom/movable/screen/alert/proc/remove_owner(mob/source, force)
+	SIGNAL_HANDLER  // COMSIG_PARENT_QDELETING
+	if(owner == source && !isnull(owner))
+		UnregisterSignal(owner, COMSIG_PARENT_QDELETING)
+		owner = null
+
+/atom/movable/screen/alert/Destroy()
+	if(owner)
+		UnregisterSignal(owner, COMSIG_PARENT_QDELETING)
+	owner = null
+	severity = 0
+	master = null
+	screen_loc = ""
+	return ..()
+
+/atom/movable/screen/alert/Click(location, control, params)
+	..()
+	if(!usr || !usr.client)
+		return FALSE
+	if(usr != owner)
+		to_chat(usr, "<span class='notice'>Only [owner] can use that!</span>")
+		return FALSE
+	var/paramslist = params2list(params)
+	if(paramslist["shift"]) // screen objects don't do the normal Click() stuff so we'll cheat
+		to_chat(usr, "<span class='boldnotice'>[name]</span> - <span class='info'>[desc]</span>")
+		return FALSE
+	if(master)
+		usr.client.Click(master, location, control, params)
+	return TRUE
 
 /atom/movable/screen/alert/MouseEntered(location, control, params)
 	. = ..()
@@ -310,7 +352,7 @@ or something covering your eyes."
 	icon_state = "embeddedobject"
 
 /atom/movable/screen/alert/embeddedobject/Click()
-	if(isliving(usr))
+	if(isliving(usr) && ..())
 		var/mob/living/carbon/human/M = usr
 		return M.help_shake_act(M)
 
@@ -333,7 +375,7 @@ or shoot a gun to move around via Newton's 3rd Law of Motion."
 	icon_state = "fire"
 
 /atom/movable/screen/alert/fire/Click()
-	if(isliving(usr))
+	if(isliving(usr) && ..())
 		var/mob/living/L = usr
 		return L.resist()
 
@@ -343,7 +385,7 @@ or shoot a gun to move around via Newton's 3rd Law of Motion."
 	icon_state = "direction_lock"
 
 /atom/movable/screen/alert/direction_lock/Click()
-	if(isliving(usr))
+	if(isliving(usr) && ..())
 		var/mob/living/L = usr
 		return L.clear_forced_look()
 
@@ -406,7 +448,7 @@ Recharging stations are available in robotics, the dormitory bathrooms, and the
 	desc = "You have merged with a diona gestalt and are now part of it's biomass. You can still wiggle yourself free though."
 
 /atom/movable/screen/alert/nymph/Click()
-	if(!usr || !usr.client)
+	if(!..())
 		return
 	if(isnymph(usr))
 		var/mob/living/simple_animal/diona/D = usr
@@ -417,7 +459,7 @@ Recharging stations are available in robotics, the dormitory bathrooms, and the
 	desc = "You have merged with one or more diona nymphs. Click here to drop it (or one of them)."
 
 /atom/movable/screen/alert/gestalt/Click()
-	if(!usr || !usr.client)
+	if(!..())
 		return
 
 	var/list/nymphs = list()
@@ -465,7 +507,7 @@ so as to remain in compliance with the most up-to-date laws."
 	return ..()
 
 /atom/movable/screen/alert/hackingapc/Click()
-	if(!usr || !usr.client)
+	if(!..())
 		return
 	if(!target)
 		return
@@ -491,7 +533,7 @@ so as to remain in compliance with the most up-to-date laws."
 	return ..()
 
 /atom/movable/screen/alert/mech_port_available/Click()
-	if(!usr || !usr.client)
+	if(!..())
 		return
 	if(!ismecha(usr.loc) || !target)
 		return
@@ -507,7 +549,7 @@ so as to remain in compliance with the most up-to-date laws."
 	icon_state = "mech_port_x"
 
 /atom/movable/screen/alert/mech_port_disconnect/Click()
-	if(!usr || !usr.client)
+	if(!..())
 		return
 	if(!ismecha(usr.loc))
 		return
@@ -566,7 +608,7 @@ so as to remain in compliance with the most up-to-date laws."
 	timeout = 300
 
 /atom/movable/screen/alert/notify_cloning/Click()
-	if(!usr || !usr.client)
+	if(!..())
 		return
 	var/mob/dead/observer/G = usr
 	G.reenter_corpse()
@@ -585,6 +627,8 @@ so as to remain in compliance with the most up-to-date laws."
 	overlays += I
 
 /atom/movable/screen/alert/ghost/Click()
+	if(!..())
+		return
 	var/mob/living/carbon/human/infected_user = usr
 	if(!istype(infected_user) || infected_user.stat == DEAD)
 		infected_user.clear_alert("ghost_nest")
@@ -640,7 +684,7 @@ so as to remain in compliance with the most up-to-date laws."
 	return ..()
 
 /atom/movable/screen/alert/notify_action/Click()
-	if(!usr || !usr.client)
+	if(!..())
 		return
 	var/mob/dead/observer/G = usr
 
@@ -721,7 +765,7 @@ so as to remain in compliance with the most up-to-date laws."
 	var/stoner = null
 
 /atom/movable/screen/alert/notify_soulstone/Click()
-	if(!usr || !usr.client)
+	if(!..())
 		return
 	if(stone)
 		if(tgui_alert(usr, "Do you want to be captured by [stoner]'s soul stone? This will destroy your corpse and make it \
@@ -738,6 +782,7 @@ so as to remain in compliance with the most up-to-date laws."
 	icon_state = "map_vote"
 
 /atom/movable/screen/alert/notify_mapvote/Click()
+	// ehh sure let observers click on it if they really want, who cares
 	usr.client.vote()
 
 //OBJECT-BASED
@@ -756,11 +801,14 @@ so as to remain in compliance with the most up-to-date laws."
 	desc = "You're legcuffed, which slows you down considerably. Click the alert to free yourself."
 
 /atom/movable/screen/alert/restrained/Click()
-	if(isliving(usr))
-		var/mob/living/L = usr
-		return L.resist()
+	if(!isliving(usr) || !..())
+		return
+	var/mob/living/L = usr
+	return L.resist()
 
 /atom/movable/screen/alert/restrained/buckled/Click()
+	if(!isliving(usr) || !..())
+		return
 	var/mob/living/L = usr
 	if(!istype(L) || !L.can_resist())
 		return
@@ -770,20 +818,23 @@ so as to remain in compliance with the most up-to-date laws."
 // PRIVATE = only edit, use, or override these if you're editing the system as a whole
 
 // Re-render all alerts - also called in /datum/hud/show_hud() because it's needed there
-/datum/hud/proc/reorganize_alerts()
+/datum/hud/proc/reorganize_alerts(mob/viewmob)
+	var/mob/screenmob = viewmob || mymob
+	if(!screenmob.client)
+		return
 	var/list/alerts = mymob.alerts
 	if(!alerts)
 		return FALSE
 	var/icon_pref
 	if(!hud_shown)
 		for(var/i in 1 to length(alerts))
-			mymob.client.screen -= alerts[alerts[i]]
+			screenmob.client.screen -= alerts[alerts[i]]
 		return TRUE
 	for(var/i in 1 to length(alerts))
 		var/atom/movable/screen/alert/alert = alerts[alerts[i]]
 		if(alert.icon_state == "template")
 			if(!icon_pref)
-				icon_pref = ui_style2icon(mymob.client.prefs.UI_style)
+				icon_pref = ui_style2icon(screenmob.client.prefs.UI_style)
 			alert.icon = icon_pref
 		switch(i)
 			if(1)
@@ -799,24 +850,12 @@ so as to remain in compliance with the most up-to-date laws."
 			else
 				. = ""
 		alert.screen_loc = .
-		mymob.client.screen |= alert
+		screenmob.client.screen |= alert
+	if(!viewmob)
+		for(var/viewer in mymob.observers)
+			reorganize_alerts(viewer)
 	return TRUE
 
-/atom/movable/screen/alert/Click(location, control, params)
-	if(!usr || !usr.client)
-		return
-	var/paramslist = params2list(params)
-	if(paramslist["shift"]) // screen objects don't do the normal Click() stuff so we'll cheat
-		to_chat(usr, "<span class='boldnotice'>[name]</span> - <span class='info'>[desc]</span>")
-		return
-	if(master)
-		return usr.client.Click(master, location, control, params)
-
-/atom/movable/screen/alert/Destroy()
-	severity = 0
-	master = null
-	screen_loc = ""
-	return ..()
 
 /// Gives the player the option to succumb while in critical condition
 /atom/movable/screen/alert/succumb
@@ -825,7 +864,7 @@ so as to remain in compliance with the most up-to-date laws."
 	icon_state = "succumb"
 
 /atom/movable/screen/alert/succumb/Click()
-	if(!usr || !usr.client)
+	if(!..())
 		return
 	var/mob/living/living_owner = usr
 	if(!istype(usr))

code/_onclick/hud/alien_hud.dm

@@ -146,19 +146,22 @@
 			inv_slots[inv.slot_id] = inv
 			inv.update_icon()
 
-/datum/hud/alien/persistent_inventory_update()
+/datum/hud/alien/persistent_inventory_update(mob/viewer)
 	if(!mymob)
 		return
 	var/mob/living/carbon/alien/humanoid/H = mymob
+	var/mob/screenmob = viewer || H
 	if(hud_version != HUD_STYLE_NOHUD)
 		if(H.r_hand)
 			H.r_hand.screen_loc = ui_rhand
-			H.client.screen += H.r_hand
+			screenmob.client.screen += H.r_hand
 		if(H.l_hand)
 			H.l_hand.screen_loc = ui_lhand
-			H.client.screen += H.l_hand
+			screenmob.client.screen += H.l_hand
 	else
 		if(H.r_hand)
 			H.r_hand.screen_loc = null
+			screenmob.client.screen -= H.r_hand
 		if(H.l_hand)
 			H.l_hand.screen_loc = null
+			screenmob.client.screen -= H.l_hand

code/_onclick/hud/fullscreen.dm

@@ -49,16 +49,17 @@
 	for(var/category in screens)
 		clear_fullscreen(category)
 
-/datum/hud/proc/reload_fullscreen()
-	if(mymob.client)
-		var/atom/movable/screen/fullscreen/screen
-		var/list/screens = mymob.screens
-		for(var/category in screens)
-			screen = screens[category]
-			if(screen.should_show_to(mymob))
-				mymob.client.screen |= screen
-				continue
-			mymob.client.screen -= screen
+/mob/proc/reload_fullscreen()
+	if(!client)
+		return
+	var/atom/movable/screen/fullscreen/screen
+	for(var/category in screens)
+		screen = screens[category]
+		if(screen.should_show_to(src))
+			screen.update_for_view(client.view)
+			client.screen |= screen
+		else
+			client.screen -= screen
 
 /atom/movable/screen/fullscreen
 	icon = 'icons/mob/screen_full.dmi'

code/_onclick/hud/ghost_hud.dm

@@ -110,7 +110,24 @@
 	for(var/atom/movable/screen/S in (static_inventory + toggleable_inventory))
 		S.hud = src
 
-/datum/hud/ghost/show_hud()
-	mymob.client.screen = list()
-	mymob.client.screen += static_inventory
-	..()
+/datum/hud/ghost/show_hud(version = 0, mob/viewmob)
+	// don't show this HUD if observing; show the HUD of the observee
+	var/mob/dead/observer/O = mymob
+	if(istype(O) && O.mob_observed)
+		plane_masters_update()
+		return FALSE
+
+	. = ..()
+	if(!.)
+		return
+	var/mob/screenmob = viewmob || mymob
+	screenmob.client.screen += static_inventory
+
+
+// We should only see observed mob alerts.
+/datum/hud/ghost/reorganize_alerts(mob/viewmob)
+	var/mob/dead/observer/O = mymob
+	if(istype(O) && O.mob_observed)
+		return
+	return ..()
+

code/_onclick/hud/hud_datum.dm

@@ -11,7 +11,7 @@
 	var/hud_shown = TRUE
 	/// Current displayed version of the HUD
 	var/hud_version = 1
-	/// Whether or not their toggleable inventory
+	/// Whether or not their toggleable inventory (generally their contents on the left) is expanded
 	var/inventory_shown = TRUE
 	/// This is to hide the buttons that can be used via hotkeys. (hotkeybuttons list of buttons)
 	var/hotkey_ui_hidden = FALSE
@@ -147,14 +147,22 @@
 	QDEL_NULL(screentip_text)
 	return ..()
 
-/datum/hud/proc/show_hud(version = 0)
+/**
+ * Shows this hud's hud to some mob
+ *
+ * Arguments
+ * * version - denotes which style should be displayed. blank or 0 means "next version"
+ * * viewmob - what mob to show the hud to. Can be this hud's mob, can be another mob, can be null (will use this hud's mob if so)
+ */
+/datum/hud/proc/show_hud(version = 0, mob/viewmob)
 	if(!ismob(mymob))
 		return FALSE
-
-	if(!mymob.client)
+	var/mob/screenmob = viewmob || mymob
+	if(!screenmob.client)
 		return FALSE
 
-	mymob.client.screen = list()
+	screenmob.client.clear_screen()
+	screenmob.client.apply_clickcatcher()
 
 	var/display_hud_version = version
 	if(!display_hud_version)	//If 0 or blank, display the next hud version
@@ -166,15 +174,15 @@
 		if(HUD_STYLE_STANDARD)	//Default HUD
 			hud_shown = TRUE	//Governs behavior of other procs
 			if(length(static_inventory))
-				mymob.client.screen += static_inventory
-			if(length(toggleable_inventory) && inventory_shown)
-				mymob.client.screen += toggleable_inventory
-			if(length(hotkeybuttons) && !hotkey_ui_hidden)
-				mymob.client.screen += hotkeybuttons
+				screenmob.client.screen += static_inventory
+			if(length(toggleable_inventory) && screenmob.hud_used?.inventory_shown)
+				screenmob.client.screen += toggleable_inventory
+			if(length(hotkeybuttons) && !screenmob.hud_used?.hotkey_ui_hidden)
+				screenmob.client.screen += hotkeybuttons
 			if(length(infodisplay))
-				mymob.client.screen += infodisplay
+				screenmob.client.screen += infodisplay
 
-			mymob.client.screen += toggle_palette
+			screenmob.client.screen += toggle_palette
 
 			if(action_intent)
 				action_intent.screen_loc = initial(action_intent.screen_loc) //Restore intent selection to the original position
@@ -182,33 +190,33 @@
 		if(HUD_STYLE_REDUCED)	//Reduced HUD
 			hud_shown = FALSE	//Governs behavior of other procs
 			if(length(static_inventory))
-				mymob.client.screen -= static_inventory
+				screenmob.client.screen -= static_inventory
 			if(length(toggleable_inventory))
-				mymob.client.screen -= toggleable_inventory
+				screenmob.client.screen -= toggleable_inventory
 			if(length(hotkeybuttons))
-				mymob.client.screen -= hotkeybuttons
+				screenmob.client.screen -= hotkeybuttons
 			if(length(infodisplay))
-				mymob.client.screen += infodisplay
+				screenmob.client.screen += infodisplay
 
 			//These ones are a part of 'static_inventory', 'toggleable_inventory' or 'hotkeybuttons' but we want them to stay
 			if(inv_slots[SLOT_HUD_LEFT_HAND])
-				mymob.client.screen += inv_slots[SLOT_HUD_LEFT_HAND]	//we want the hands to be visible
+				screenmob.client.screen += inv_slots[SLOT_HUD_LEFT_HAND]	//we want the hands to be visible
 			if(inv_slots[SLOT_HUD_RIGHT_HAND])
-				mymob.client.screen += inv_slots[SLOT_HUD_RIGHT_HAND]	//we want the hands to be visible
+				screenmob.client.screen += inv_slots[SLOT_HUD_RIGHT_HAND]	//we want the hands to be visible
 			if(action_intent)
-				mymob.client.screen += action_intent		//we want the intent switcher visible
+				screenmob.client.screen += action_intent		//we want the intent switcher visible
 				action_intent.screen_loc = ui_acti_alt	//move this to the alternative position, where zone_select usually is.
 
 		if(HUD_STYLE_NOHUD)	//No HUD
 			hud_shown = FALSE	//Governs behavior of other procs
 			if(length(static_inventory))
-				mymob.client.screen -= static_inventory
+				screenmob.client.screen -= static_inventory
 			if(length(toggleable_inventory))
-				mymob.client.screen -= toggleable_inventory
+				screenmob.client.screen -= toggleable_inventory
 			if(length(hotkeybuttons))
-				mymob.client.screen -= hotkeybuttons
+				screenmob.client.screen -= hotkeybuttons
 			if(length(infodisplay))
-				mymob.client.screen -= infodisplay
+				screenmob.client.screen -= infodisplay
 
 		if(HUD_STYLE_ACTIONHUD)	//No HUD
 			hud_shown = TRUE	//Governs behavior of other procs
@@ -220,36 +228,46 @@
 				mymob.client.screen -= infodisplay
 
 	hud_version = display_hud_version
-	persistent_inventory_update()
-	mymob.update_action_buttons(1)
-	reorganize_alerts()
-	reload_fullscreen()
-	update_parallax_pref(mymob)
+	persistent_inventory_update(screenmob)
+	screenmob.update_action_buttons(TRUE)
+	reorganize_alerts(screenmob)
+	screenmob.reload_fullscreen()
+	update_parallax_pref(screenmob)
+	if(!viewmob)
+		// working off of mymob
+		plane_masters_update()
+		for(var/M in mymob.observers)
+			show_hud(hud_version, M)
+	else if(viewmob.hud_used)
+		viewmob.hud_used.plane_masters_update()
+		viewmob.show_other_mob_action_buttons(mymob)
 	plane_masters_update()
+	return TRUE
 
 /datum/hud/proc/plane_masters_update()
 	// Plane masters are always shown to OUR mob, never to observers
 	for(var/thing in plane_masters)
 		var/atom/movable/screen/plane_master/PM = plane_masters[thing]
 		PM.backdrop(mymob)
-		mymob.client.screen += PM
+		mymob.client?.screen += PM
 
-/datum/hud/human/show_hud(version = 0)
+/datum/hud/human/show_hud(version = 0, mob/viewmob)
 	. = ..()
 	if(!.)
 		return
-	hidden_inventory_update()
+	var/mob/screenmob = viewmob || mymob
+	hidden_inventory_update(screenmob)
 
-/datum/hud/robot/show_hud(version = 0)
+/datum/hud/robot/show_hud(version = 0, mob/viewmob)
 	. = ..()
 	if(!.)
 		return
-	update_robot_modules_display()
+	update_robot_modules_display(viewmob)
 
-/datum/hud/proc/hidden_inventory_update()
+/datum/hud/proc/hidden_inventory_update(mob/viewer)
 	return
 
-/datum/hud/proc/persistent_inventory_update()
+/datum/hud/proc/persistent_inventory_update(mob/viewer)
 	return
 
 /mob/proc/hide_hud()

code/_onclick/hud/human_hud.dm

@@ -6,14 +6,22 @@
 	icon_state = "toggle"
 
 /atom/movable/screen/human/toggle/Click()
-	if(usr.hud_used.inventory_shown)
+
+	var/mob/targetmob = usr
+
+	if(isobserver(usr))
+		if(ishuman(usr.client.eye) && (usr.client.eye != usr))
+			var/mob/M = usr.client.eye
+			targetmob = M
+
+	if(usr.hud_used.inventory_shown && targetmob.hud_used)
 		usr.hud_used.inventory_shown = FALSE
-		usr.client.screen -= usr.hud_used.toggleable_inventory
+		usr.client.screen -= targetmob.hud_used.toggleable_inventory
 	else
 		usr.hud_used.inventory_shown = TRUE
-		usr.client.screen += usr.hud_used.toggleable_inventory
+		usr.client.screen += targetmob.hud_used.toggleable_inventory
 
-	usr.hud_used.hidden_inventory_update()
+	targetmob.hud_used.hidden_inventory_update(usr)
 
 /atom/movable/screen/human/equip
 	name = "equip"
@@ -21,7 +29,7 @@
 
 /atom/movable/screen/human/equip/Click()
 	if(ismecha(usr.loc)) // stops inventory actions in a mech
-		return 1
+		return TRUE
 	var/mob/living/carbon/human/H = usr
 	H.quick_equip()
 
@@ -33,6 +41,8 @@
 	screen_loc = ui_lingstingdisplay
 
 /atom/movable/screen/ling/sting/Click()
+	if(isobserver(usr))
+		return
 	var/datum/antagonist/changeling/cling = usr.mind.has_antag_datum(/datum/antagonist/changeling)
 	cling?.chosen_sting?.unset_sting()
 
@@ -389,100 +399,118 @@
 		else
 			crafting.invisibility = initial(crafting.invisibility)
 
-/datum/hud/human/hidden_inventory_update()
+/datum/hud/human/hidden_inventory_update(mob/viewer)
 	if(!mymob)
 		return
 	var/mob/living/carbon/human/H = mymob
-	if(inventory_shown && hud_version == HUD_STYLE_STANDARD)
+
+	var/mob/screenmob = viewer || H
+	if(screenmob.hud_used.inventory_shown && screenmob.hud_used.hud_shown && screenmob.hud_used.hud_version == HUD_STYLE_STANDARD)
+
 		if(H.shoes)
 			H.shoes.screen_loc = ui_shoes
-			H.client.screen += H.shoes
+			screenmob.client.screen += H.shoes
 		if(H.gloves)
 			H.gloves.screen_loc = ui_gloves
-			H.client.screen += H.gloves
+			screenmob.client.screen += H.gloves
 		if(H.l_ear)
 			H.l_ear.screen_loc = ui_l_ear
-			H.client.screen += H.l_ear
+			screenmob.client.screen += H.l_ear
 		if(H.r_ear)
 			H.r_ear.screen_loc = ui_r_ear
-			H.client.screen += H.r_ear
+			screenmob.client.screen += H.r_ear
 		if(H.glasses)
 			H.glasses.screen_loc = ui_glasses
-			H.client.screen += H.glasses
+			screenmob.client.screen += H.glasses
 		if(H.w_uniform)
 			H.w_uniform.screen_loc = ui_iclothing
-			H.client.screen += H.w_uniform
+			screenmob.client.screen += H.w_uniform
 		if(H.wear_suit)
 			H.wear_suit.screen_loc = ui_oclothing
-			H.client.screen += H.wear_suit
+			screenmob.client.screen += H.wear_suit
 		if(H.wear_mask)
 			H.wear_mask.screen_loc = ui_mask
-			H.client.screen += H.wear_mask
+			screenmob.client.screen += H.wear_mask
 		if(H.head)
 			H.head.screen_loc = ui_head
-			H.client.screen += H.head
+			screenmob.client.screen += H.head
 	else
-		if(H.shoes)		H.shoes.screen_loc = null
-		if(H.gloves)	H.gloves.screen_loc = null
-		if(H.l_ear)		H.l_ear.screen_loc = null
-		if(H.r_ear)		H.r_ear.screen_loc = null
-		if(H.glasses)	H.glasses.screen_loc = null
-		if(H.w_uniform)	H.w_uniform.screen_loc = null
-		if(H.wear_suit)	H.wear_suit.screen_loc = null
-		if(H.wear_mask)	H.wear_mask.screen_loc = null
-		if(H.head)		H.head.screen_loc = null
+		if(H.shoes)
+			screenmob.client.screen -= H.shoes
+		if(H.gloves)
+			screenmob.client.screen -= H.gloves
+		if(H.l_ear)
+			screenmob.client.screen -= H.l_ear
+		if(H.r_ear)
+			screenmob.client.screen -= H.r_ear
+		if(H.glasses)
+			screenmob.client.screen -= H.glasses
+		if(H.w_uniform)
+			screenmob.client.screen -= H.w_uniform
+		if(H.wear_suit)
+			screenmob.client.screen -= H.wear_suit
+		if(H.wear_mask)
+			screenmob.client.screen -= H.wear_mask
+		if(H.head)
+			screenmob.client.screen -= H.head
 
-/datum/hud/human/persistent_inventory_update()
+/datum/hud/human/persistent_inventory_update(mob/viewer)
 	if(!mymob)
 		return
+	..()
 	var/mob/living/carbon/human/H = mymob
-	if(hud_version == HUD_STYLE_STANDARD)
-		if(H.s_store)
-			H.s_store.screen_loc = ui_sstore1
-			H.client.screen += H.s_store
-		if(H.wear_id)
-			H.wear_id.screen_loc = ui_id
-			H.client.screen += H.wear_id
-		if(H.wear_pda)
-			H.wear_pda.screen_loc = ui_pda
-			H.client.screen += H.wear_pda
-		if(H.belt)
-			H.belt.screen_loc = ui_belt
-			H.client.screen += H.belt
-		if(H.back)
-			H.back.screen_loc = ui_back
-			H.client.screen += H.back
-		if(H.l_store)
-			H.l_store.screen_loc = ui_storage1
-			H.client.screen += H.l_store
-		if(H.r_store)
-			H.r_store.screen_loc = ui_storage2
-			H.client.screen += H.r_store
-	else
-		if(H.s_store)
-			H.s_store.screen_loc = null
-		if(H.wear_id)
-			H.wear_id.screen_loc = null
-		if(H.wear_pda)
-			H.wear_pda.screen_loc = null
-		if(H.belt)
-			H.belt.screen_loc = null
-		if(H.back)
-			H.back.screen_loc = null
-		if(H.l_store)
-			H.l_store.screen_loc = null
-		if(H.r_store)
-			H.r_store.screen_loc = null
+	var/mob/screenmob = viewer || H
+
+	if(screenmob.hud_used)
+		if(screenmob.hud_used.hud_shown && screenmob.hud_used.hud_version == HUD_STYLE_STANDARD)
+			if(H.s_store)
+				H.s_store.screen_loc = ui_sstore1
+				screenmob.client.screen += H.s_store
+			if(H.wear_id)
+				H.wear_id.screen_loc = ui_id
+				screenmob.client.screen += H.wear_id
+			if(H.wear_pda)
+				H.wear_pda.screen_loc = ui_pda
+				screenmob.client.screen += H.wear_pda
+			if(H.belt)
+				H.belt.screen_loc = ui_belt
+				screenmob.client.screen += H.belt
+			if(H.back)
+				H.back.screen_loc = ui_back
+				screenmob.client.screen += H.back
+			if(H.l_store)
+				H.l_store.screen_loc = ui_storage1
+				screenmob.client.screen += H.l_store
+			if(H.r_store)
+				H.r_store.screen_loc = ui_storage2
+				screenmob.client.screen += H.r_store
+		else
+			if(H.s_store)
+				screenmob.client.screen -= H.s_store
+			if(H.wear_id)
+				screenmob.client.screen -= H.wear_id
+			if(H.wear_pda)
+				screenmob.client.screen -= H.wear_pda
+			if(H.belt)
+				screenmob.client.screen -= H.belt
+			if(H.back)
+				screenmob.client.screen -= H.back
+			if(H.l_store)
+				screenmob.client.screen -= H.l_store
+			if(H.r_store)
+				screenmob.client.screen -= H.r_store
 
 	if(hud_version != HUD_STYLE_NOHUD)
 		if(H.r_hand)
 			H.r_hand.screen_loc = ui_rhand
-			H.client.screen += H.r_hand
+			screenmob.client.screen += H.r_hand
 		if(H.l_hand)
 			H.l_hand.screen_loc = ui_lhand
-			H.client.screen += H.l_hand
+			screenmob.client.screen += H.l_hand
 	else
 		if(H.r_hand)
-			H.r_hand.screen_loc = null
+			screenmob.r_hand.screen_loc = null
+			screenmob.client.screen -= H.r_hand
 		if(H.l_hand)
-			H.l_hand.screen_loc = null
+			screenmob.l_hand.screen_loc = null
+			screenmob.client.screen -= H.l_hand

code/_onclick/hud/parallax.dm

@@ -1,6 +1,9 @@
-/datum/hud/proc/create_parallax()
-	var/client/C = mymob.client
-	if(!apply_parallax_pref())
+/datum/hud/proc/create_parallax(mob/viewmob)
+	var/mob/screenmob = viewmob || mymob
+	if(!screenmob.client)
+		return
+	var/client/C = screenmob.client
+	if(!apply_parallax_pref(screenmob))
 		return
 	// this is needed so it blends properly with the space plane and blackness plane.
 	var/atom/movable/screen/plane_master/space/S = plane_masters["[PLANE_SPACE]"]
@@ -34,16 +37,20 @@
 
 	C.screen |= (C.parallax_layers + C.parallax_static_layers_tail)
 
-/datum/hud/proc/remove_parallax()
-	var/client/C = mymob.client
+/datum/hud/proc/remove_parallax(mob/viewmob)
+	var/mob/screenmob = viewmob || mymob
+	var/client/C = screenmob.client
 	C.screen -= (C.parallax_layers_cached + C.parallax_static_layers_tail)
 	C.parallax_layers = null
 	var/atom/movable/screen/plane_master/space/S = plane_masters["[PLANE_SPACE]"]
 	S.color = null
 	S.appearance_flags &= ~NO_CLIENT_COLOR
 
-/datum/hud/proc/apply_parallax_pref()
-	var/client/C = mymob.client
+/datum/hud/proc/apply_parallax_pref(mob/viewmob)
+	var/mob/screen_mob = viewmob || mymob
+	var/client/C = screen_mob.client
+	if(!istype(C))
+		return FALSE
 	if(C.prefs)
 		var/pref = C.prefs.parallax
 		if(isnull(pref))
@@ -72,16 +79,22 @@
 	C.parallax_layers_max = 4
 	return TRUE
 
-/datum/hud/proc/update_parallax_pref()
-	remove_parallax()
-	create_parallax()
-	update_parallax()
+/datum/hud/proc/update_parallax_pref(mob/viewmob)
+	var/mob/screen_mob = viewmob || mymob
+	if(!screen_mob.client)
+		return
+	remove_parallax(screen_mob)
+	create_parallax(screen_mob)
+	update_parallax(screen_mob)
 
 // This sets which way the current shuttle is moving (returns true if the shuttle has stopped moving so the caller can append their animation)
 // Well, it would if our shuttle code had dynamic areas
-/datum/hud/proc/set_parallax_movedir(new_parallax_movedir, skip_windups)
+/datum/hud/proc/set_parallax_movedir(mob/viewmob, new_parallax_movedir, skip_windups)
 	. = FALSE
-	var/client/C = mymob.client
+	var/mob/screen_mob = viewmob || mymob
+	var/client/C = screen_mob.client
+	if(!istype(C))
+		return
 	if(new_parallax_movedir == C.parallax_movedir)
 		return
 	var/animatedir = new_parallax_movedir
@@ -157,8 +170,9 @@
 		animate(L, transform = L.transform, time = 0, loop = -1, flags = ANIMATION_END_NOW)
 		animate(transform = matrix(), time = T)
 
-/datum/hud/proc/update_parallax()
-	var/client/C = mymob.client
+/datum/hud/proc/update_parallax(mob/viewmob)
+	var/mob/screenmob = viewmob || mymob
+	var/client/C = screenmob.client
 	var/turf/posobj = get_turf(C.eye)
 	if(!posobj)
 		return
@@ -167,9 +181,9 @@
 	// Update the movement direction of the parallax if necessary (for shuttles)
 	var/area/shuttle/SA = areaobj
 	if(!SA || !SA.moving)
-		set_parallax_movedir(0)
+		set_parallax_movedir(screenmob, 0)
 	else
-		set_parallax_movedir(SA.parallax_move_direction)
+		set_parallax_movedir(screenmob, SA.parallax_move_direction)
 
 	var/force
 	if(!C.previous_turf || (C.previous_turf.z != posobj.z))
@@ -193,7 +207,7 @@
 
 	for(var/thing in C.parallax_layers)
 		var/atom/movable/screen/parallax_layer/L = thing
-		L.update_status(mymob)
+		L.update_status(screenmob)
 		if(L.view_sized != C.view)
 			L.update_o(C.view)
 

code/_onclick/hud/robot_hud.dm

@@ -1,23 +1,34 @@
 /atom/movable/screen/robot
 	icon = 'icons/mob/screen_robot.dmi'
 
+/atom/movable/screen/robot/Click()
+	. = ..()
+	if(isobserver(usr))
+		return TRUE
+
 /atom/movable/screen/robot/module
 	name = "cyborg module"
 	icon_state = "nomod"
 
 /atom/movable/screen/robot/module/Click()
-	if(isrobot(usr))
+	if(isrobot(usr) && !..())
 		var/mob/living/silicon/robot/R = usr
-		if(R.module)
-			R.hud_used.toggle_show_robot_modules()
-			return 1
-		R.pick_module()
+		if(!R.module)
+			R.pick_module()
+			return
+
+	// we can let ghosts mess with this one
+	usr.hud_used.toggle_show_robot_modules(usr)
+	return TRUE
+
 
 /atom/movable/screen/robot/module1
 	name = "module1"
 	icon_state = "inv1"
 
 /atom/movable/screen/robot/module1/Click()
+	if(..())
+		return
 	if(isrobot(usr))
 		var/mob/living/silicon/robot/R = usr
 		R.toggle_module(1)
@@ -27,6 +38,8 @@
 	icon_state = "inv2"
 
 /atom/movable/screen/robot/module2/Click()
+	if(..())
+		return
 	if(isrobot(usr))
 		var/mob/living/silicon/robot/R = usr
 		R.toggle_module(2)
@@ -36,6 +49,8 @@
 	icon_state = "inv3"
 
 /atom/movable/screen/robot/module3/Click()
+	if(..())
+		return
 	if(isrobot(usr))
 		var/mob/living/silicon/robot/R = usr
 		R.toggle_module(3)
@@ -46,6 +61,8 @@
 	icon_state = "radio"
 
 /atom/movable/screen/robot/radio/Click()
+	if(..())
+		return
 	if(issilicon(usr))
 		var/mob/living/silicon/robot/R = usr
 		R.radio_menu()
@@ -55,6 +72,8 @@
 	icon_state = "store"
 
 /atom/movable/screen/robot/store/Click()
+	if(..())
+		return
 	if(isrobot(usr))
 		var/mob/living/silicon/robot/R = usr
 		R.uneq_active()
@@ -66,6 +85,8 @@
 	screen_loc = ui_borg_lamp
 
 /atom/movable/screen/robot/lamp/Click()
+	if(..())
+		return
 	if(isrobot(usr))
 		var/mob/living/silicon/robot/R = usr
 		R.control_headlamp()
@@ -75,6 +96,8 @@
 	icon_state = "ionpulse0"
 
 /atom/movable/screen/robot/thrusters/Click()
+	if(..())
+		return
 	var/mob/living/silicon/robot/R = usr
 	R.toggle_ionpulse()
 
@@ -83,11 +106,23 @@
 	icon_state = "running"
 
 /atom/movable/screen/robot/mov_intent/Click()
+	if(..())
+		return
 	usr.toggle_move_intent()
 
+/datum/hud/robot
+	var/shown_robot_modules = FALSE	// Used to determine whether they have the module menu shown or not
+	var/atom/movable/screen/robot_modules_background
+
 /datum/hud/robot/New(mob/user)
 	..()
 
+
+	robot_modules_background = new()
+	robot_modules_background.icon_state = "block"
+	robot_modules_background.layer = HUD_LAYER // Objects that appear on screen are on layer 20, UI should be just below it.
+	robot_modules_background.plane = HUD_PLANE
+
 	var/atom/movable/screen/using
 	var/mob/living/silicon/robot/mymobR = mymob
 
@@ -184,41 +219,51 @@
 
 	return ..()
 
-/datum/hud/proc/toggle_show_robot_modules()
+/datum/hud/proc/toggle_show_robot_modules(mob/viewmob)
+	return
+
+/datum/hud/robot/toggle_show_robot_modules(mob/viewmob)
+	var/mob/screenmob = viewmob || mymob
+	if(istype(viewmob.hud_used, /datum/hud/robot))
+		var/datum/hud/robot/robohud = screenmob.hud_used
+		robohud.shown_robot_modules = !robohud.shown_robot_modules
+
+	update_robot_modules_display(viewmob)
+
+/datum/hud/proc/update_robot_modules_display(mob/viewer)
+	return
+
+/datum/hud/robot/update_robot_modules_display(mob/viewer)
 	if(!isrobot(mymob))
 		return
 
 	var/mob/living/silicon/robot/R = mymob
 
-	R.shown_robot_modules = !R.shown_robot_modules
-	update_robot_modules_display()
-
-/datum/hud/proc/update_robot_modules_display()
-	if(!isrobot(mymob))
-		return
-
-	var/mob/living/silicon/robot/R = mymob
+	var/mob/screenmob = viewer || R
 
 	if(!R.client)
 		return
 
 	if(!R.module)
+		shown_robot_modules = FALSE
+		screenmob.client.screen -= robot_modules_background
+		screenmob.client?.screen -= screenmob.hud_used.module_store_icon
 		return
 
-	if(R.shown_robot_modules && hud_version == HUD_STYLE_STANDARD)
+	if(shown_robot_modules && hud_shown && hud_version == HUD_STYLE_STANDARD)
 		//Modules display is shown
-		R.client.screen += module_store_icon	//"store" icon
+		screenmob.client.screen += module_store_icon	//"store" icon
 
 		if(!R.module.modules)
 			to_chat(usr, "<span class='danger'>Selected module has no modules to select.</span>")
 			return
 
-		if(!R.robot_modules_background)
+		if(!robot_modules_background)
 			return
 
 		var/display_rows = CEILING(length(R.module.modules) / 8, 1)
-		R.robot_modules_background.screen_loc = "CENTER-4:16,SOUTH+1:7 to CENTER+3:16,SOUTH+[display_rows]:7"
-		R.client.screen += R.robot_modules_background
+		robot_modules_background.screen_loc = "CENTER-4:16,SOUTH+1:7 to CENTER+3:16,SOUTH+[display_rows]:7"
+		screenmob.client.screen += robot_modules_background
 
 		var/x = -4	//Start at CENTER-4,SOUTH+1
 		var/y = 1
@@ -226,7 +271,7 @@
 		for(var/atom/movable/A in R.module.modules)
 			if((A != R.module_state_1) && (A != R.module_state_2) && (A != R.module_state_3))
 				//Module is not currently active
-				R.client.screen += A
+				screenmob.client.screen += A
 				if(x < 0)
 					A.screen_loc = "CENTER[x]:16,SOUTH+[y]:7"
 				else
@@ -241,11 +286,39 @@
 
 	else
 		//Modules display is hidden
-		R.client.screen -= module_store_icon
+		screenmob.client.screen -= module_store_icon
 
 		for(var/atom/A in R.module.modules)
 			if((A != R.module_state_1) && (A != R.module_state_2) && (A != R.module_state_3))
 				//Module is not currently active
-				R.client.screen -= A
-		R.shown_robot_modules = FALSE
-		R.client.screen -= R.robot_modules_background
+				screenmob.client.screen -= A
+		shown_robot_modules = FALSE
+		screenmob.client.screen -= robot_modules_background
+
+/datum/hud/robot/persistent_inventory_update(mob/viewer)
+	if(!mymob)
+		return
+	var/mob/living/silicon/robot/R = mymob
+
+	var/mob/screenmob = viewer || R
+
+	var/held_items = list(R.module_state_1, R.module_state_2, R.module_state_3)
+	if(!screenmob.hud_used)
+		return
+	if(screenmob.hud_used.hud_shown)
+		for(var/i in 1 to length(held_items))
+			var/obj/item/I = held_items[i]
+			if(I)
+				switch(i)
+					if(1)
+						I.screen_loc = ui_inv1
+					if(2)
+						I.screen_loc = ui_inv2
+					if(3)
+						I.screen_loc = ui_inv3
+					else
+						return
+				screenmob.client.screen += I
+	else
+		for(var/obj/item/I in held_items)
+			screenmob.client.screen -= I

code/_onclick/hud/screen_objects.dm

@@ -367,6 +367,8 @@
 	screen_loc = ui_crafting
 
 /atom/movable/screen/craft/Click()
+	if(!isliving(usr))
+		return
 	var/mob/living/M = usr
 	M.OpenCraftingMenu()
 
@@ -396,24 +398,26 @@
 	object_overlays.Cut()
 
 /atom/movable/screen/inventory/proc/add_overlays()
-	var/mob/user = hud.mymob
+	var/mob/user = hud?.mymob
 
-	if(hud && user && slot_id)
-		var/obj/item/holding = user.get_active_hand()
+	if(!user || !slot_id || user != usr)
+		return
 
-		if(!holding || user.get_item_by_slot(slot_id))
-			return
+	var/obj/item/holding = user.get_active_hand()
 
-		var/image/item_overlay = image(holding)
-		item_overlay.alpha = 92
+	if(!holding || user.get_item_by_slot(slot_id))
+		return
 
-		if(!user.can_equip(holding, slot_id, disable_warning = TRUE))
-			item_overlay.color = "#ff0000"
-		else
-			item_overlay.color = "#00ff00"
+	var/image/item_overlay = image(holding)
+	item_overlay.alpha = 92
 
-		object_overlays += item_overlay
-		add_overlay(object_overlays)
+	if(!user.can_equip(holding, slot_id, TRUE))
+		item_overlay.color = "#ff0000"
+	else
+		item_overlay.color = "#00ff00"
+
+	object_overlays += item_overlay
+	add_overlay(object_overlays)
 
 /atom/movable/screen/inventory/MouseDrop(atom/over)
 	cut_overlay(object_overlays)

code/datums/action.dm

@@ -16,6 +16,8 @@
 	var/default_button_position = SCRN_OBJ_IN_LIST
 	/// Map of huds viewing a button with our action -> their button
 	var/list/viewers = list()
+	/// Whether or not this will be shown to observers
+	var/show_to_observers = TRUE
 
 
 /datum/action/New(Target)
@@ -49,6 +51,8 @@
 		Remove(owner)
 	owner = M
 	RegisterSignal(owner, COMSIG_PARENT_QDELETING, PROC_REF(clear_ref), override = TRUE)
+	SEND_SIGNAL(src, COMSIG_ACTION_GRANTED, owner)
+	SEND_SIGNAL(owner, COMSIG_MOB_GRANTED_ACTION, src)
 	GiveAction(M)
 
 /datum/action/proc/Remove(mob/remove_from)
@@ -64,6 +68,9 @@
 	if(isnull(owner))
 		return
 
+	SEND_SIGNAL(src, COMSIG_ACTION_REMOVED, owner)
+	SEND_SIGNAL(owner, COMSIG_MOB_REMOVED_ACTION, src)
+
 	if(target == owner)
 		RegisterSignal(target, COMSIG_PARENT_QDELETING, PROC_REF(clear_ref), override = TRUE)
 	if(owner == remove_from)

code/datums/components/orbiter.dm

@@ -163,6 +163,7 @@
 		orbiter.animate_movement = SLIDE_STEPS
 		if(!QDELETED(parent))
 			SEND_SIGNAL(parent, COMSIG_ATOM_ORBIT_STOP, orbiter)
+		SEND_SIGNAL(orbiter, COMSIG_ATOM_ORBITER_STOP, parent)
 
 		orbiter.transform = get_cached_transform(orbiter)
 		orbiter.layer = get_orbiter_layer(orbiter)

code/game/objects/items/weapons/storage/storage_base.dm

@@ -199,12 +199,9 @@
 	orient2hud(user) // this only needs to happen to make .contents show properly as screen objects.
 	if(user.s_active)
 		user.s_active.hide_from(user) // If there's already an interface open, close it.
-	user.client.screen -= boxes
-	user.client.screen -= closer
-	user.client.screen -= contents
-	user.client.screen += boxes
-	user.client.screen += closer
-	user.client.screen += contents
+	user.client.screen |= boxes
+	user.client.screen |= closer
+	user.client.screen |= contents
 	user.s_active = src
 	LAZYDISTINCTADD(mobs_viewing, user)
 
@@ -245,6 +242,9 @@
 	update_viewers()
 
 /obj/item/storage/proc/open(mob/user)
+	if(isobserver(user))
+		show_to(user)
+		return
 	if(use_sound && isliving(user))
 		playsound(loc, use_sound, 50, TRUE, -5)
 
@@ -459,6 +459,10 @@
 	if(user)
 		if(user.client && user.s_active != src)
 			user.client.screen -= I
+		if(length(user.observers))
+			for(var/mob/observer in user.observers)
+				if(observer.client && observer.s_active != src)
+					observer.client.screen -= I
 		I.dropped(user, TRUE)
 	add_fingerprint(user)
 

code/modules/admin/admin_verbs.dm

@@ -12,6 +12,8 @@ GLOBAL_LIST_INIT(admin_verbs_admin, list(
 	/client/proc/invisimin,				/*allows our mob to go invisible/visible*/
 	/datum/admins/proc/announce,		/*priority announce something to all clients.*/
 	/client/proc/admin_ghost,			/*allows us to ghost/reenter body at will*/
+	/client/proc/admin_observe,			/*allows us to freely observe mobs */
+	/client/proc/admin_observe_target,			/*and gives it to us on right click*/
 	/client/proc/toggle_view_range,		/*changes how far we can see*/
 	/client/proc/cmd_admin_pm_context,	/*right-click adminPM interface*/
 	/client/proc/cmd_admin_pm_panel,	/*admin-pm list*/
@@ -196,13 +198,17 @@ GLOBAL_LIST_INIT(admin_verbs_mod, list(
 	/client/proc/dsay,
 	/datum/admins/proc/show_player_panel,
 	/client/proc/ban_panel,
-	/client/proc/debug_variables		/*allows us to -see- the variables of any instance in the game. +VAREDIT needed to modify*/
+	/client/proc/debug_variables,		/*allows us to -see- the variables of any instance in the game. +VAREDIT needed to modify*/
+	/client/proc/admin_observe,
+	/client/proc/admin_observe_target,
 ))
 GLOBAL_LIST_INIT(admin_verbs_mentor, list(
 	/client/proc/cmd_admin_pm_context,	/*right-click adminPM interface*/
 	/client/proc/cmd_admin_pm_panel,	/*admin-pm list*/
 	/client/proc/cmd_admin_pm_by_key_panel,	/*admin-pm list by key*/
 	/client/proc/openMentorTicketUI,
+	/client/proc/admin_observe,  /* Allow mentors to observe as well, though they face some limitations */
+	/client/proc/admin_observe_target,
 	/client/proc/cmd_mentor_say	/* mentor say*/
 	// cmd_mentor_say is added/removed by the toggle_mentor_chat verb
 ))
@@ -339,13 +345,22 @@ GLOBAL_LIST_INIT(view_runtimes_verbs, list(
 	to_chat(src, "<span class='interface'>All of your adminverbs are now visible.</span>")
 	SSblackbox.record_feedback("tally", "admin_verb", 1, "Show Admin Verbs") //If you are copy-pasting this, ensure the 2nd parameter is unique to the new proc!
 
-/client/proc/admin_ghost()
-	set category = "Admin"
-	set name = "Aghost"
+/client/proc/mentor_ghost()
+	var/is_mentor = check_rights(R_MENTOR, FALSE)
+	var/is_full_admin = check_rights(R_ADMIN|R_MOD, FALSE)
 
-	if(!check_rights(R_ADMIN|R_MOD))
+	if(!is_mentor && !is_full_admin)
+		to_chat(src, "<span class='warning'>You aren't allowed to use this!</span>")
 		return
 
+	// mentors are allowed only if they have the observe trait, which is given on observe.
+	// they should also not be given this proc.
+	if(!is_full_admin && (is_mentor && !HAS_MIND_TRAIT(mob, TRAIT_MENTOR_OBSERVING) || !is_mentor))
+		return
+
+	do_aghost()
+
+/client/proc/do_aghost()
 	if(isobserver(mob))
 		//re-enter
 		var/mob/dead/observer/ghost = mob
@@ -372,6 +387,134 @@ GLOBAL_LIST_INIT(view_runtimes_verbs, list(
 		// TODO: SStgui.on_transfer() to move windows from old and new
 		SSblackbox.record_feedback("tally", "admin_verb", 1, "Aghost") //If you are copy-pasting this, ensure the 2nd parameter is unique to the new proc!
 
+/client/proc/admin_ghost()
+	set category = "Admin"
+	set name = "Aghost"
+
+	if(!check_rights(R_ADMIN|R_MOD))
+		return
+
+	do_aghost()
+
+/// Allow an admin to observe someone.
+/// mentors are allowed to use this verb while living, but with some stipulations:
+/// if they attempt to do anything that would stop their orbit, they will immediately be returned to their body.
+/client/proc/admin_observe()
+	set name = "Aobserve"
+	set category = "Admin"
+	if(!check_rights(R_ADMIN|R_MOD|R_MENTOR))
+		return
+
+	if(isnewplayer(mob))
+		to_chat(src, "<span class='warning'>You cannot aobserve while in the lobby. Please join or observe first.</span>")
+		return
+
+	var/mob/target
+
+	target = tgui_input_list(mob, "Select a mob to observe", "Aobserve", GLOB.player_list)
+	if(isnull(target))
+		return
+	if(target == src)
+		to_chat(src, "<span class='warning'>You can't observe yourself!</span>")
+		return
+
+	if(isobserver(target))
+		to_chat(src, "<span class='warning'>[target] is a ghost, and cannot be observed.</span>")
+		return
+
+	if(isnewplayer(target))
+		to_chat(src, "<span class='warning'>[target] is in the lobby, and cannot be observed.</span>")
+		return
+
+	admin_observe_target(target)
+
+/client/proc/cleanup_admin_observe(mob/dead/observer/ghost)
+	if(!istype(ghost) || !ghost.mob_observed)
+		return FALSE
+
+	// un-follow them
+	ghost.cleanup_observe()
+	// if it's a mentor, make sure they go back to their body.
+	if(HAS_TRAIT(mob.mind, TRAIT_MENTOR_OBSERVING))
+		// handler will handle removing the trait
+		mob.stop_orbit()
+	log_admin("[key_name(src)] has de-activated Aobserve")
+	SSblackbox.record_feedback("tally", "admin_verb", 1, "Aobserve")
+	return TRUE
+
+/// targeted form of admin_observe: this should only appear in the right-click menu.
+/client/proc/admin_observe_target(mob/target as mob in GLOB.mob_list)
+	set name = "\[Admin\] Aobserve"
+	set category = null
+
+	if(!check_rights(R_ADMIN|R_MOD|R_MENTOR, mob))
+		return
+
+	var/full_admin = check_rights(R_ADMIN|R_MOD, FALSE, mob)
+
+	if(isnewplayer(mob))
+		to_chat(src, "<span class='warning'>You cannot aobserve while in the lobby. Please join or observe first.</span>")
+		return
+
+	if(isnewplayer(target))
+		to_chat(src, "<span class='warning'>[target] is currently in the lobby.</span>")
+		return
+
+	if(isobserver(target))
+		to_chat(src, "<span class='warning'>You can't observe a ghost.</span>")
+		return
+
+	if(cleanup_admin_observe(mob))
+		return
+
+	if(isnull(target) || target == src)
+		// let the default one find the target if there isn't one
+		admin_observe()
+		return
+
+	// observers don't need to ghost, so we don't need to worry about adding any traits
+	if(isobserver(mob))
+		var/mob/dead/observer/ghost = mob
+		SSblackbox.record_feedback("tally", "admin_verb", 1, "Aobserve")
+		ghost.do_observe(target)
+		return
+
+	log_admin("[key_name(src)] has Aobserved out of their body to follow [target]")
+	do_aghost()
+	var/mob/dead/observer/ghost = mob
+
+	if(!full_admin)
+		// if they're a me and they're alive, add the MENTOR_OBSERVINGtrait to ensure that they can only go back to their body.
+		// we need to handle this here because when you aghost, your mob gets set to the ghost. Oops!
+		ADD_TRAIT(mob.mind, TRAIT_MENTOR_OBSERVING, MENTOR_OBSERVING)
+		RegisterSignal(ghost, COMSIG_ATOM_ORBITER_STOP, PROC_REF(on_mentor_observe_end), override = TRUE)
+		to_chat(src, "<span class='notice'>You have temporarily observed [target], either move or observe again to un-observe.</span>")
+		log_admin("[key_name(src)] has mobserved out of their body to follow [target].")
+	else
+		log_admin("[key_name(src)] is aobserving [target].")
+
+
+	ghost.do_observe(target)
+
+/client/proc/on_mentor_observe_end(atom/movable/us, atom/movable/orbited)
+	SIGNAL_HANDLER  // COMSIG_ATOM_ORBITER_STOP
+	if(!isobserver(mob))
+		log_and_message_admins("A mentor somehow managed to end observing while not being a ghost. Please investigate and notify coders.")
+		return
+	var/mob/dead/observer/ghost = mob
+
+	// just to be safe
+	ghost.cleanup_observe()
+
+	REMOVE_TRAIT(mob.mind, TRAIT_MENTOR_OBSERVING, MENTOR_OBSERVING)
+	UnregisterSignal(mob, COMSIG_ATOM_ORBITER_STOP)
+
+	if(!ghost.reenter_corpse())
+		// tell everyone since this is kinda nasty.
+		log_debug("Mentor [key_name_mentor(src)] was unable to re-enter their body after mentor observing.")
+		log_and_message_admins("[key_name_mentor(src)] was unable to re-enter their body after mentor observing.")
+		to_chat(src, "<span class='userdanger'>Unable to return you to your body after mentor ghosting. If your body still exists, please contact a coder, and you should probably ahelp.</span>")
+
 /client/proc/invisimin()
 	set name = "Invisimin"
 	set category = "Admin"

code/modules/admin/player_panel.dm

@@ -86,7 +86,8 @@
 					body += "<a href='byond://?src=[usr.UID()];priv_msg="+client_ckey+"'>PM</a> - "
 					body += "<a href='byond://?src=[UID()];subtlemessage="+mobUID+"'>SM</a> - "
 					body += "<a href='byond://?src=[UID()];adminplayerobservefollow="+mobUID+"'>FLW</a> - "
-					body += "<a href='byond://?src=[UID()];adminalert="+mobUID+"'>ALERT</a>"
+					body += "<a href='byond://?src=[UID()];adminalert="+mobUID+"'>ALERT</a> - "
+					body += "<a href='byond://?src=[UID()];adminobserve="+mobUID+"'>OBS</a>"
 					if(eyeUID)
 						body += "|<a href='byond://?src=[UID()];adminplayerobservefollow="+eyeUID+"'>EYE</a>"
 					body += "<br>"

code/modules/admin/topic.dm

@@ -1613,6 +1613,17 @@
 		show_player_panel(H)
 		//H.regenerate_icons()
 
+	else if(href_list["adminobserve"])
+		if(!check_rights(R_ADMIN|R_MOD|R_MENTOR))
+			return
+		var/client/C = usr.client
+		var/mob/M = locateUID(href_list["adminobserve"])
+
+		if(!ismob(M))
+			to_chat(usr, "<span class='warning'>This can only be used on instances of type /mob</span>")
+			return
+		C.admin_observe_target(M)
+
 	else if(href_list["adminplayeropts"])
 		var/mob/M = locateUID(href_list["adminplayeropts"])
 
@@ -3586,3 +3597,5 @@
 		var/mob/dead/observer/O = target
 		if(O.mind && O.mind.current)
 			. += "|[ADMIN_FLW(O.mind.current,"BDY")]"
+	else if(ismob(target))
+		. += "|[ADMIN_OBS(target, "OBS")]"

code/modules/admin/verbs/adminpm.dm

@@ -178,6 +178,7 @@
 	var/ping_link = check_rights(R_ADMIN, 0, mob) ? "(<a href='byond://?src=[pm_tracker.UID()];ping=[C.key]'>PING</a>)" : ""
 	var/ticket_link
 	var/alert_link = check_rights(R_ADMIN, FALSE, mob) ? "(<a href='byond://?src=[pm_tracker.UID()];adminalert=[C.mob.UID()]'>ALERT</a>)" : ""
+	var/observe_link = check_rights(R_MENTOR, FALSE, mob) ? "([ADMIN_OBS(C, "OBS")])" : ""
 	if(ticket_id != -1)
 		if(message_type == MESSAGE_TYPE_MENTORPM)
 			ticket_link = "(<a href='byond://?_src_=holder;openticket=[ticket_id];is_mhelp=1'>TICKET</a>)"
@@ -190,7 +191,7 @@
 		receive_window_link = ticket_link
 	else if(message_type == MESSAGE_TYPE_ADMINPM && check_rights(R_ADMIN, 0, C.mob))
 		receive_window_link = ticket_link
-	receive_message = "<span class='[receive_span]'>[type] from-<b>[receive_pm_type] [C.holder ? key_name(src, TRUE, type, ticket_id = ticket_id) : key_name_hidden(src, TRUE, type, ticket_id = ticket_id)]</b>:<br><br>[emoji_msg][C.holder ? "<br>[ping_link] [receive_window_link] [alert_link]" : ""]</span>"
+	receive_message = "<span class='[receive_span]'>[type] from-<b>[receive_pm_type] [C.holder ? key_name(src, TRUE, type, ticket_id = ticket_id) : key_name_hidden(src, TRUE, type, ticket_id = ticket_id)]</b>:<br><br>[emoji_msg][C.holder ? "<br>[ping_link] [receive_window_link] [alert_link] [observe_link]" : ""]</span>"
 	if(message_type == MESSAGE_TYPE_MENTORPM)
 		receive_message = chat_box_mhelp(receive_message)
 	else
@@ -202,7 +203,7 @@
 			send_window_link = ticket_link
 		else if(message_type == MESSAGE_TYPE_ADMINPM && check_rights(R_ADMIN, 0, mob))
 			send_window_link = ticket_link
-		var/send_message = "<span class='[send_span]'>[send_pm_type][type] to-<b>[holder ? key_name(C, TRUE, type, ticket_id = ticket_id) : key_name_hidden(C, TRUE, type, ticket_id = ticket_id)]</b>:<br><br>[emoji_msg]</span><br>[ping_link] [send_window_link] [alert_link]"
+		var/send_message = "<span class='[send_span]'>[send_pm_type][type] to-<b>[holder ? key_name(C, TRUE, type, ticket_id = ticket_id) : key_name_hidden(C, TRUE, type, ticket_id = ticket_id)]</b>:<br><br>[emoji_msg]</span><br>[ping_link] [send_window_link] [alert_link] [observe_link]"
 		if(message_type == MESSAGE_TYPE_MENTORPM)
 			send_message = chat_box_mhelp(send_message)
 		else
@@ -211,9 +212,9 @@
 
 	var/third_party_message
 	if(message_type == MESSAGE_TYPE_MENTORPM)
-		third_party_message = chat_box_mhelp("<span class='mentorhelp'>[type]: [key_name(src, TRUE, type, ticket_id = ticket_id)]-&gt;[key_name(C, TRUE, type, ticket_id = ticket_id)]:<br><br>[emoji_msg]<br>[ping_link] [ticket_link] [alert_link]</span>")
+		third_party_message = chat_box_mhelp("<span class='mentorhelp'>[type]: [key_name(src, TRUE, type, ticket_id = ticket_id)]-&gt;[key_name(C, TRUE, type, ticket_id = ticket_id)]:<br><br>[emoji_msg]<br>[ping_link] [ticket_link] [alert_link] [observe_link]</span>")
 	else
-		third_party_message = chat_box_ahelp("<span class='adminhelp'>[type]: [key_name(src, TRUE, type, ticket_id = ticket_id)]-&gt;[key_name(C, TRUE, type, ticket_id = ticket_id)]:<br><br>[emoji_msg]<br>[ping_link] [ticket_link] [alert_link]</span>")
+		third_party_message = chat_box_ahelp("<span class='adminhelp'>[type]: [key_name(src, TRUE, type, ticket_id = ticket_id)]-&gt;[key_name(C, TRUE, type, ticket_id = ticket_id)]:<br><br>[emoji_msg]<br>[ping_link] [ticket_link] [alert_link] [observe_link]</span>")
 
 	//play the recieving admin the adminhelp sound (if they have them enabled)
 	//non-admins always hear the sound, as they cannot toggle it

code/modules/client/client_procs.dm

@@ -1172,6 +1172,14 @@
 	else
 		src << link(GLOB.configuration.system.region_map[choice])
 
+/client/proc/set_eye(new_eye)
+	if(new_eye == eye)
+		return
+	eye = new_eye
+
+/client/proc/clear_screen()
+	for(var/object in screen)
+		screen -= object
 
 /client/verb/reload_graphics()
 	set category = "Special Verbs"

code/modules/mob/dead/observer/observer_base.dm

@@ -20,6 +20,8 @@ GLOBAL_DATUM_INIT(ghost_crew_monitor, /datum/ui_module/crew_monitor/ghost, new)
 	move_resist = INFINITY	//  don't get pushed around
 	invisibility = INVISIBILITY_OBSERVER
 	blocks_emissive = FALSE // Ghosts are transparent, duh
+	hud_type = /datum/hud/ghost
+	speaks_ooc = TRUE
 	var/can_reenter_corpse
 	var/bootime = FALSE
 	var/started_as_observer //This variable is set to 1 when you enter the game as an observer.
@@ -41,8 +43,8 @@ GLOBAL_DATUM_INIT(ghost_crew_monitor, /datum/ui_module/crew_monitor/ghost, new)
 	var/datum/orbit_menu/orbit_menu
 	/// The "color" their runechat would have had
 	var/alive_runechat_color = "#FFFFFF"
-	hud_type = /datum/hud/ghost
-	speaks_ooc = TRUE
+	/// UID of the mob which we are currently observing
+	var/mob_observed
 
 /mob/dead/observer/New(mob/body=null, flags=1)
 	set_invisibility(GLOB.observer_default_invisibility)
@@ -120,6 +122,8 @@ GLOBAL_DATUM_INIT(ghost_crew_monitor, /datum/ui_module/crew_monitor/ghost, new)
 	if(seerads)
 		STOP_PROCESSING(SSobj, src)
 	remove_observer_verbs()
+	if(mob_observed)
+		cleanup_observe()
 	return ..()
 
 /mob/dead/observer/examine(mob/user)
@@ -184,25 +188,37 @@ Works together with spawning an observer, noted above.
 	return 1
 
 /mob/proc/ghostize(flags = GHOST_CAN_REENTER, user_color, ghost_name)
-	if(key)
-		if(player_logged) //if they have disconnected we want to remove their SSD overlay
-			overlays -= image('icons/effects/effects.dmi', icon_state = "zzz_glow")
-		if(GLOB.non_respawnable_keys[ckey])
-			flags &= ~GHOST_CAN_REENTER
-		var/mob/dead/observer/ghost = new(src, flags)	//Transfer safety to observer spawning proc.
-		ghost.timeofdeath = src.timeofdeath //BS12 EDIT
-		if(ghost.can_reenter_corpse)
-			ADD_TRAIT(ghost, TRAIT_RESPAWNABLE, GHOSTED)
-		else
-			GLOB.non_respawnable_keys[ckey] = 1
-		if(user_color)
-			add_atom_colour(user_color, ADMIN_COLOUR_PRIORITY)
-			ghost.color = user_color
-		if(ghost_name)
-			ghost.name = ghost_name
-		ghost.key = key
-		ghost.client?.init_verbs()
-		return ghost
+	if(!key)
+		return
+	if(player_logged) // if they have disconnected we want to remove their SSD overlay
+		overlays -= image('icons/effects/effects.dmi', icon_state = "zzz_glow")
+	if(GLOB.non_respawnable_keys[ckey])
+		flags &= ~GHOST_CAN_REENTER
+	var/mob/dead/observer/ghost = new(src, flags) // Transfer safety to observer spawning proc.
+	ghost.timeofdeath = src.timeofdeath // BS12 EDIT
+	if(ghost.can_reenter_corpse)
+		ADD_TRAIT(ghost, TRAIT_RESPAWNABLE, GHOSTED)
+	else
+		GLOB.non_respawnable_keys[ckey] = 1
+
+	// mods, mentors, and the like will have admin observe anyway, so this is moot
+	if(((key in GLOB.antag_hud_users) || (key in GLOB.roundstart_observer_keys)) && !check_rights(R_MOD | R_ADMIN | R_MENTOR, FALSE, src))
+		ghost.verbs |= /mob/dead/observer/proc/do_observe
+		ghost.verbs |= /mob/dead/observer/proc/observe
+	if(user_color)
+		add_atom_colour(user_color, ADMIN_COLOUR_PRIORITY)
+		ghost.color = user_color
+	if(ghost_name)
+		ghost.name = ghost_name
+	ghost.key = key
+
+	ghost.client?.init_verbs()
+
+	for(var/mob/dead/observer/obs in observers)
+		obs.cleanup_observe()
+
+
+	return ghost
 
 /*
 This is the proc mobs get to turn into a ghost. Forked from ghostize due to compatibility issues.
@@ -492,52 +508,67 @@ This is the proc mobs get to turn into a ghost. Forked from ghostize due to comp
 	GLOB.ghost_crew_monitor.ui_interact(src)
 
 /mob/dead/observer/proc/add_observer_verbs()
-	verbs.Add(/mob/dead/observer/proc/ManualFollow)
+	verbs.Add(
+		/mob/dead/observer/proc/ManualFollow,
+	)
 
 /mob/dead/observer/proc/remove_observer_verbs()
-	verbs.Remove(/mob/dead/observer/proc/ManualFollow)
+	verbs.Remove(
+		/mob/dead/observer/proc/ManualFollow,
+		// these might not necessarily be here, but we want to make sure they're gonezo anyway
+		/mob/dead/observer/proc/observe,
+		/mob/dead/observer/proc/do_observe
+	)
 
-// This is the ghost's follow verb with an argument
+// This is the ghost's follow verb with an argument.
+// We need to do the usr check on this verb itself, but the logic follows.
 /mob/dead/observer/proc/ManualFollow(atom/movable/target)
 	set name = "\[Observer\] Orbit"
 	set desc = "Orbits the specified movable atom."
 	set category = null
 
-	if(!target || !isobserver(usr))
+	// this usr check is apparently necessary for security
+	if(!isobserver(usr))
 		return
 
+	return do_manual_follow(target)
+
+// We need to check usr when calling the verb, but we still want this logic to be accessible elsewhere
+/mob/dead/observer/proc/do_manual_follow(atom/movable/target)
 	if(!get_turf(target))
 		return
 
-	if(target != src)
-		if(src in target.get_orbiters())
-			return
+	if(!target || target == src)
+		return
 
-		var/icon/I = icon(target.icon,target.icon_state,target.dir)
+	if(src in target.get_orbiters())
+		return
 
-		var/orbitsize = (I.Width()+I.Height())*0.5
+	var/icon/I = icon(target.icon, target.icon_state, target.dir)
 
-		if(orbitsize == 0)
-			orbitsize = 40
+	var/orbitsize = (I.Width() + I.Height())*0.5
 
-		orbitsize -= (orbitsize/world.icon_size)*(world.icon_size*0.25)
+	if(orbitsize == 0)
+		orbitsize = 40
 
-		var/rot_seg
+	orbitsize -= (orbitsize/world.icon_size)*(world.icon_size*0.25)
 
-		switch(ghost_orbit)
-			if(GHOST_ORBIT_TRIANGLE)
-				rot_seg = 3
-			if(GHOST_ORBIT_SQUARE)
-				rot_seg = 4
-			if(GHOST_ORBIT_PENTAGON)
-				rot_seg = 5
-			if(GHOST_ORBIT_HEXAGON)
-				rot_seg = 6
-			else //Circular
-				rot_seg = 36 //360/10 bby, smooth enough aproximation of a circle
+	var/rot_seg
 
-		to_chat(src, "<span class='notice'>Now following [target].</span>")
-		orbit(target,orbitsize, FALSE, 20, rot_seg)
+	switch(ghost_orbit)
+		if(GHOST_ORBIT_TRIANGLE)
+			rot_seg = 3
+		if(GHOST_ORBIT_SQUARE)
+			rot_seg = 4
+		if(GHOST_ORBIT_PENTAGON)
+			rot_seg = 5
+		if(GHOST_ORBIT_HEXAGON)
+			rot_seg = 6
+		else // Circular
+			rot_seg = 36 // 360/10 bby, smooth enough aproximation of a circle
+
+	to_chat(src, "<span class='notice'>Now following [target].</span>")
+	orbit(target, orbitsize, FALSE, 20, rot_seg)
 
 /mob/dead/observer/orbit(atom/A, radius = 10, clockwise = FALSE, rotation_speed = 20, rotation_segments = 36, pre_rotation = TRUE, lock_in_orbit = FALSE, force_move = FALSE, orbit_layer = GHOST_LAYER)
 	setDir(2)//reset dir so the right directional sprites show up
@@ -825,6 +856,102 @@ This is the proc mobs get to turn into a ghost. Forked from ghostize due to comp
 /mob/dead/observer/get_runechat_color()
 	return alive_runechat_color
 
+/mob/dead/observer/proc/observe()
+	set name = "Observe"
+	set desc = "Observe a mob."
+	set category = "Ghost"
+
+	var/list/possible_targets = list()
+	for(var/mob/living/L in GLOB.player_list)
+		if(!L.mind)
+			continue
+		possible_targets.Add(L)
+
+	if(!length(possible_targets))
+		to_chat(src, "<span class='warning'>There's nobody for you to observe!</span>")
+		return
+
+	var/mob/target = tgui_input_list(usr, "Please, select a player!", "Observe", possible_targets)
+	if(!istype(target) || QDELETED(target))
+		return
+	do_observe(target)
+
+/mob/dead/observer/proc/do_observe(mob/mob_eye)
+	set name = "\[Observer\] Observe"
+	set desc = "Observe the target mob."
+	set category = null
+
+	if(isnewplayer(mob_eye))
+		to_chat(src, "<span class='warning'>You can't observe someone in the lobby.</span>")
+		return
+
+	if(isobserver(mob_eye))
+		to_chat(src, "<span class='warning'>You can't observe a ghost.</span>")
+		return
+
+	if(!mob_eye.mind)
+		to_chat(src, "<span class='notice'>You can only observe mobs that have been or are being inhabited by a player!</span>")
+		return
+
+	if(mob_eye == src)
+		to_chat(src, "<span class='warning'>You can't observe yourself!</span>")
+		return
+
+	if(mob_observed)
+		// clean up first
+		stop_orbit()
+		cleanup_observe()
+
+	// Istype so we filter out points of interest that are not mobs
+	if(client && ismob(mob_eye))
+		// follow the mob so they're technically right there for visible messages n stuff
+		// call the sub-proc since the base one checks for usr
+		do_manual_follow(mob_eye)
+		client.set_eye(mob_eye)
+		add_attack_logs(src, mob_eye, "observed", ATKLOG_ALMOSTALL)
+		client.perspective = EYE_PERSPECTIVE
+		if(mob_eye.hud_used)
+			client.clear_screen()
+			LAZYOR(mob_eye.observers, src)
+			mob_eye.hud_used?.show_hud(mob_eye.hud_used.hud_version, src)
+			mob_observed = mob_eye.UID()
+
+
+		// mentor observing grants you this trait, and provides its own signal handler for this
+		if(!HAS_MIND_TRAIT(src, TRAIT_MENTOR_OBSERVING))
+			RegisterSignal(src, COMSIG_ATOM_ORBITER_STOP, PROC_REF(on_observer_orbit_end), override = TRUE)
+		else
+			if(!check_rights(R_MENTOR, FALSE, src))
+				log_debug("[key_name(src)] has the the mobserve trait while observing, but isn't a mentor. This is likely an error, and may result in them getting stuck")
+
+/// Clean up observing
+/mob/dead/observer/proc/cleanup_observe()
+	if(isnull(mob_observed))
+		return
+
+	var/mob/target = locateUID(mob_observed)
+	add_attack_logs(src, target, "un-observed", ATKLOG_ALL)
+	mob_observed = null
+	reset_perspective(null)
+	client?.perspective = initial(client.perspective)
+	set_sight(initial(sight))
+	UnregisterSignal(src, COMSIG_ATOM_ORBITER_STOP)
+
+	if(s_active)
+		var/obj/item/storage/bag = s_active
+		s_active = null
+		bag.update_viewers(src)
+
+	if(!QDELETED(target) && istype(target))
+		hide_other_mob_action_buttons(target)
+		target.observers -= src
+
+/mob/dead/observer/proc/on_observer_orbit_end(mob/follower, atom)
+	SIGNAL_HANDLER	// COMSIG_ATOM_ORBITER_STOP
+	if(HAS_MIND_TRAIT(src, TRAIT_MENTOR_OBSERVING))
+		log_debug("[key_name(src)] ended up in regular cleanup_observe rather than the mentor cleanup observe despite having TRAIT_MENTOR_OBSERVING. This is likely a bug and may result in them being stuck outside of their bodies.")
+	cleanup_observe()
+
 /mob/dead/observer/proc/update_dead_radio()
 	if(get_preference(PREFTOGGLE_CHAT_GHOSTRADIO))
 		GLOB.deadchat_radio.listeners |= src

code/modules/mob/dead/observer/observer_logout.dm

@@ -1,6 +1,9 @@
 /mob/dead/observer/Logout()
 	if(client)
 		client.images -= GLOB.ghost_images
+	if(mob_observed && ismob(locateUID(mob_observed)))
+		cleanup_observe()
+
 	..()
 	spawn(0)
 		if(src && !key)	//we've transferred to another mob. This ghost should be deleted.

code/modules/mob/living/carbon/carbon_update_icons.dm

@@ -49,6 +49,8 @@
 			r_hand.screen_loc = ui_rhand
 			client.screen += r_hand
 
+		update_observer_view(r_hand)
+
 /mob/living/carbon/update_inv_l_hand(ignore_cuffs)
 	if(handcuffed && !ignore_cuffs)
 		drop_l_hand()
@@ -57,6 +59,7 @@
 		if(client && hud_used && hud_used.hud_version != HUD_STYLE_NOHUD)
 			l_hand.screen_loc = ui_lhand
 			client.screen += l_hand
+		update_observer_view(l_hand)
 
 /mob/living/carbon/update_inv_wear_mask()
 	if(istype(wear_mask, /obj/item/clothing/mask))
@@ -86,3 +89,17 @@
 /mob/living/carbon/proc/update_hud_back(obj/item/I)
 	return
 
+/mob/living/carbon/proc/update_observer_view(obj/item/worn_item, inventory)
+	if(!length(observers))
+		return
+	for(var/mob/dead/observe as anything in observers)
+		if(observe.client && observe.client.eye == src)
+			if(observe.hud_used)
+				if(inventory && !observe.hud_used.inventory_shown)
+					continue
+				observe.client.screen += worn_item
+		else
+			observers -= observe
+			if(!length(observers))
+				observers.Cut()
+				break

code/modules/mob/living/carbon/human/human_inventory.dm

@@ -186,6 +186,13 @@
 		update_inv_r_hand()
 
 	I.screen_loc = null
+	if(client)
+		client.screen -= I
+	if(length(observers))
+		for(var/mob/dead/observe as anything in observers)
+			if(observe.client)
+				observe.client.screen -= I
+
 	I.forceMove(src)
 	I.equipped(src, slot, initial)
 	I.layer = ABOVE_HUD_LAYER
@@ -271,8 +278,8 @@
 				var/obj/item/clothing/head/hat = I
 				if(hat.vision_flags || hat.see_in_dark || !isnull(hat.lighting_alpha))
 					update_sight()
+			// this calls update_inv_head() on its own
 			head_update(I)
-			update_inv_head()
 		if(SLOT_HUD_SHOES)
 			shoes = I
 			update_inv_shoes()

code/modules/mob/living/carbon/human/human_update_icons.dm

@@ -567,10 +567,7 @@ GLOBAL_LIST_EMPTY(damage_icon_parts)
 			inv.update_icon()
 
 	if(w_uniform && istype(w_uniform, /obj/item/clothing/under))
-		if(client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD)
-			if(hud_used.inventory_shown)			//if the inventory is open ...
-				w_uniform.screen_loc = ui_iclothing //...draw the item in the inventory screen
-			client.screen += w_uniform				//Either way, add the item to the HUD
+		update_hud_uniform(w_uniform)
 
 		var/t_color = w_uniform.item_color
 		if(!t_color)
@@ -644,9 +641,7 @@ GLOBAL_LIST_EMPTY(damage_icon_parts)
 			inv.update_icon()
 
 	if(wear_id)
-		if(client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD)
-			wear_id.screen_loc = ui_id
-			client.screen += wear_id
+		update_hud_id(wear_id)
 
 		if(w_uniform && w_uniform:displays_id)
 			overlays_standing[ID_LAYER]	= mutable_appearance('icons/mob/mob.dmi', "id", layer = -ID_LAYER)
@@ -660,10 +655,7 @@ GLOBAL_LIST_EMPTY(damage_icon_parts)
 			inv.update_icon()
 
 	if(gloves)
-		if(client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD)
-			if(hud_used.inventory_shown)			//if the inventory is open ...
-				gloves.screen_loc = ui_gloves		//...draw the item in the inventory screen
-			client.screen += gloves					//Either way, add the item to the HUD
+		update_hud_gloves(gloves)
 
 		var/t_state = gloves.item_state
 		if(!t_state)	t_state = gloves.icon_state
@@ -702,10 +694,7 @@ GLOBAL_LIST_EMPTY(damage_icon_parts)
 	if(glasses)
 		var/mutable_appearance/new_glasses
 		var/obj/item/organ/external/head/head_organ = get_organ("head")
-		if(client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD)
-			if(hud_used.inventory_shown)			//if the inventory is open ...
-				glasses.screen_loc = ui_glasses		//...draw the item in the inventory screen
-			client.screen += glasses				//Either way, add the item to the HUD
+		update_hud_glasses(glasses)
 
 		if(glasses.icon_override)
 			new_glasses = mutable_appearance(glasses.icon_override, "[glasses.icon_state]", layer = -GLASSES_LAYER)
@@ -744,10 +733,7 @@ GLOBAL_LIST_EMPTY(damage_icon_parts)
 
 	if(l_ear || r_ear)
 		if(l_ear)
-			if(client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD)
-				if(hud_used.inventory_shown)			//if the inventory is open ...
-					l_ear.screen_loc = ui_l_ear			//...draw the item in the inventory screen
-				client.screen += l_ear					//Either way, add the item to the HUD
+			update_hud_l_ear(l_ear)
 
 			var/t_type = l_ear.item_state
 			if(!t_type)
@@ -761,10 +747,7 @@ GLOBAL_LIST_EMPTY(damage_icon_parts)
 				overlays_standing[EARS_LAYER] = mutable_appearance('icons/mob/clothing/ears.dmi', "[t_type]", layer = -EARS_LAYER)
 
 		if(r_ear)
-			if(client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD)
-				if(hud_used.inventory_shown)			//if the inventory is open ...
-					r_ear.screen_loc = ui_r_ear			//...draw the item in the inventory screen
-				client.screen += r_ear					//Either way, add the item to the HUD
+			update_hud_r_ear(r_ear)
 
 			var/t_type = r_ear.item_state
 			if(!t_type)
@@ -786,10 +769,7 @@ GLOBAL_LIST_EMPTY(damage_icon_parts)
 			inv.update_icon()
 
 	if(shoes)
-		if(client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD)
-			if(hud_used.inventory_shown)			//if the inventory is open ...
-				shoes.screen_loc = ui_shoes			//...draw the item in the inventory screen
-			client.screen += shoes					//Either way, add the item to the HUD
+		update_hud_shoes(shoes)
 
 		if(!wear_suit || !(wear_suit.flags_inv & HIDESHOES))
 			var/mutable_appearance/standing
@@ -822,9 +802,7 @@ GLOBAL_LIST_EMPTY(damage_icon_parts)
 			inv.update_icon()
 
 	if(s_store)
-		if(client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD)
-			s_store.screen_loc = ui_sstore1
-			client.screen += s_store
+		update_hud_s_store(s_store)
 
 		var/t_state = s_store.item_state
 		if(!t_state)
@@ -844,6 +822,7 @@ GLOBAL_LIST_EMPTY(damage_icon_parts)
 			inv.update_icon()
 
 	if(head)
+		update_hud_head(head)
 		var/mutable_appearance/standing
 		if(head.sprite_sheets && head.sprite_sheets[dna.species.sprite_sheet_name])
 			standing = mutable_appearance(head.sprite_sheets[dna.species.sprite_sheet_name], "[head.icon_state]", layer = -HEAD_LAYER)
@@ -877,6 +856,7 @@ GLOBAL_LIST_EMPTY(damage_icon_parts)
 			belt.screen_loc = ui_belt
 
 	if(belt)
+		update_observer_view(belt)
 		var/t_state = belt.item_state
 		if(!t_state)
 			t_state = belt.icon_state
@@ -899,10 +879,7 @@ GLOBAL_LIST_EMPTY(damage_icon_parts)
 			inv.update_icon()
 
 	if(wear_suit && istype(wear_suit, /obj/item/clothing/suit))
-		if(client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD)
-			if(hud_used.inventory_shown)					//if the inventory is open ...
-				wear_suit.screen_loc = ui_oclothing	//TODO	//...draw the item in the inventory screen
-			client.screen += wear_suit						//Either way, add the item to the HUD
+		update_hud_wear_suit(wear_suit)
 
 		var/mutable_appearance/standing
 		if(wear_suit.sprite_sheets && wear_suit.sprite_sheets[dna.species.sprite_sheet_name])
@@ -950,12 +927,17 @@ GLOBAL_LIST_EMPTY(damage_icon_parts)
 
 		if(hud_used.hud_version == HUD_STYLE_STANDARD)
 			if(l_store)
-				client.screen += l_store
 				l_store.screen_loc = ui_storage1
+				if(hud_used.hud_shown)
+					client.screen += l_store
+				update_observer_view(l_store)
 
 			if(r_store)
-				client.screen += r_store
 				r_store.screen_loc = ui_storage2
+				if(hud_used.hud_shown)
+					client.screen += r_store
+					r_store.screen_loc = ui_storage2
+				update_observer_view(r_store)
 
 /mob/living/carbon/human/update_inv_wear_pda()
 	if(client && hud_used)
@@ -964,8 +946,7 @@ GLOBAL_LIST_EMPTY(damage_icon_parts)
 			inv.update_icon()
 
 		if(wear_pda)
-			client.screen += wear_pda
-			wear_pda.screen_loc = ui_pda
+			update_hud_wear_pda(wear_pda)
 
 /mob/living/carbon/human/update_inv_wear_mask()
 	..()
@@ -975,6 +956,7 @@ GLOBAL_LIST_EMPTY(damage_icon_parts)
 		if(inv)
 			inv.update_icon()
 	if(wear_mask && (istype(wear_mask, /obj/item/clothing/mask) || istype(wear_mask, /obj/item/clothing/accessory)))
+		update_hud_wear_mask(wear_mask)
 		if(!(SLOT_HUD_WEAR_MASK in check_obscured_slots()))
 			var/obj/item/organ/external/head/head_organ = get_organ("head")
 			if(!istype(head_organ))
@@ -1009,6 +991,7 @@ GLOBAL_LIST_EMPTY(damage_icon_parts)
 	..()
 	remove_overlay(BACK_LAYER)
 	if(back)
+		update_hud_back(back)
 		//determine the icon to use
 		var/t_state = back.item_state
 		if(!t_state)
@@ -1045,6 +1028,7 @@ GLOBAL_LIST_EMPTY(damage_icon_parts)
 	..()
 	remove_overlay(R_HAND_LAYER)
 	if(r_hand)
+		show_hand_to_observers(r_hand, left = FALSE)
 		var/t_state = r_hand.item_state
 		if(!t_state)
 			t_state = r_hand.icon_state
@@ -1064,6 +1048,7 @@ GLOBAL_LIST_EMPTY(damage_icon_parts)
 	..()
 	remove_overlay(L_HAND_LAYER)
 	if(l_hand)
+		show_hand_to_observers(l_hand, left = TRUE)
 		var/t_state = l_hand.item_state
 		if(!t_state)
 			t_state = l_hand.icon_state
@@ -1080,25 +1065,105 @@ GLOBAL_LIST_EMPTY(damage_icon_parts)
 
 //human HUD updates for items in our inventory
 
-//update whether our head item appears on our hud.
-/mob/living/carbon/human/update_hud_head(obj/item/I)
-	if(client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD)
-		if(hud_used.inventory_shown)
-			I.screen_loc = ui_head
-		client.screen += I
+/mob/living/carbon/human/proc/show_hand_to_observers(obj/item/worn_item, left = TRUE)
+	if(client && hud_used && hud_used.hud_version != HUD_STYLE_NOHUD)
+		worn_item.screen_loc = ui_hand_position(left ? 1 : 2)
+		client.screen += worn_item
+		if(length(observers))
+			for(var/mob/dead/observe in observers)
+				if(observe.client && observe.client.eye == src)
+					observe.client.screen += worn_item
+				else
+					observers -= observe
+					if(!length(observers))
+						observers = null
+						break
 
-//update whether our mask item appears on our hud.
-/mob/living/carbon/human/update_hud_wear_mask(obj/item/I)
-	if(client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD)
-		if(hud_used.inventory_shown)
-			I.screen_loc = ui_mask
-		client.screen += I
 
-//update whether our back item appears on our hud.
-/mob/living/carbon/human/update_hud_back(obj/item/I)
-	if(client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD)
-		I.screen_loc = ui_back
-		client.screen += I
+/mob/living/carbon/human/update_hud_wear_mask(obj/item/worn_item)
+	worn_item.screen_loc = ui_mask
+	if((client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD) && (hud_used.inventory_shown && hud_used.hud_shown))
+		client.screen += worn_item
+	update_observer_view(worn_item, TRUE)
+
+
+/mob/living/carbon/human/proc/update_hud_uniform(obj/item/worn_item)
+	worn_item.screen_loc = ui_iclothing
+	if((client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD) && (hud_used.inventory_shown && hud_used.hud_shown))
+		client.screen += worn_item
+	update_observer_view(worn_item, TRUE)
+
+/mob/living/carbon/human/proc/update_hud_id(obj/item/worn_item)
+	worn_item.screen_loc = ui_id
+	if(client && hud_used?.hud_shown && hud_used.hud_version == HUD_STYLE_STANDARD)
+		client.screen += worn_item
+	update_observer_view(worn_item)
+
+/mob/living/carbon/human/proc/update_hud_wear_pda(obj/item/worn_item)
+	worn_item.screen_loc = ui_pda
+	if(client && hud_used?.hud_shown && hud_used.hud_version == HUD_STYLE_STANDARD)
+		client.screen += worn_item
+	update_observer_view(worn_item)
+
+/mob/living/carbon/human/proc/update_hud_gloves(obj/item/worn_item)
+	worn_item.screen_loc = ui_gloves
+	if((client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD) && (hud_used.inventory_shown && hud_used.hud_shown))
+		client.screen += worn_item
+	update_observer_view(worn_item, TRUE)
+
+/mob/living/carbon/human/proc/update_hud_glasses(obj/item/worn_item)
+	worn_item.screen_loc = ui_glasses
+	if((client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD) && (hud_used.inventory_shown && hud_used.hud_shown))
+		client.screen += worn_item
+	update_observer_view(worn_item, TRUE)
+
+/mob/living/carbon/human/proc/update_hud_l_ear(obj/item/worn_item)
+	worn_item.screen_loc = ui_l_ear
+	if((client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD) && (hud_used.inventory_shown && hud_used.hud_shown))
+		client.screen += worn_item
+	update_observer_view(worn_item, TRUE)
+
+/mob/living/carbon/human/proc/update_hud_r_ear(obj/item/worn_item)
+	worn_item.screen_loc = ui_r_ear
+	if((client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD) && (hud_used.inventory_shown && hud_used.hud_shown))
+		client.screen += worn_item
+	update_observer_view(worn_item, TRUE)
+
+/mob/living/carbon/human/proc/update_hud_shoes(obj/item/worn_item)
+	worn_item.screen_loc = ui_shoes
+	if((client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD) && (hud_used.inventory_shown && hud_used.hud_shown))
+		client.screen += worn_item
+	update_observer_view(worn_item, TRUE)
+
+/mob/living/carbon/human/proc/update_hud_s_store(obj/item/worn_item)
+	worn_item.screen_loc = ui_sstore1
+	if(client && hud_used?.hud_shown && hud_used.hud_version == HUD_STYLE_STANDARD)
+		client.screen += worn_item
+	update_observer_view(worn_item, TRUE)
+
+/mob/living/carbon/human/proc/update_hud_wear_suit(obj/item/worn_item)
+	worn_item.screen_loc = ui_oclothing
+	if((client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD) && (hud_used.inventory_shown && hud_used.hud_shown))
+		client.screen += worn_item
+	update_observer_view(worn_item, TRUE)
+
+/mob/living/carbon/human/proc/update_hud_belt(obj/item/worn_item)
+	belt.screen_loc = ui_belt
+	if(client && hud_used?.hud_shown && hud_used.hud_version == HUD_STYLE_STANDARD)
+		client.screen += worn_item
+	update_observer_view(worn_item, TRUE)
+
+/mob/living/carbon/human/update_hud_head(obj/item/worn_item)
+	worn_item.screen_loc = ui_head
+	if((client && hud_used && hud_used.hud_version == HUD_STYLE_STANDARD) && (hud_used.inventory_shown && hud_used.hud_shown))
+		client.screen += worn_item
+	update_observer_view(worn_item, TRUE)
+
+/mob/living/carbon/human/update_hud_back(obj/item/worn_item)
+	worn_item.screen_loc = ui_back
+	if(client && hud_used?.hud_shown && hud_used.hud_version == HUD_STYLE_STANDARD)
+		client.screen += worn_item
+	update_observer_view(worn_item, TRUE)
 
 /mob/living/carbon/human/proc/update_wing_layer()
 	remove_overlay(WING_UNDERLIMBS_LAYER)

code/modules/mob/living/death.dm

@@ -64,7 +64,7 @@
 	if(mind && suiciding)
 		mind.suicided = TRUE
 	reset_perspective(null)
-	hud_used?.reload_fullscreen()
+	reload_fullscreen()
 	update_sight()
 	update_action_buttons_icon()
 	ADD_TRAIT(src, TRAIT_FLOORED, STAT_TRAIT)

code/modules/mob/living/silicon/robot/robot_inventory.dm

@@ -15,6 +15,7 @@
 
 	O.mouse_opacity = MOUSE_OPACITY_OPAQUE
 
+	observer_screen_update(O, add = FALSE)
 	if(client)
 		client.screen -= O
 	contents -= O
@@ -78,6 +79,7 @@
 		set_actions(O)
 	else
 		to_chat(src, "You need to disable a module first!")
+	observer_screen_update(O, add = TRUE)
 	check_module_damage(FALSE)
 	update_icons()
 
@@ -250,3 +252,25 @@
 		hands.icon_state = "nomod"
 	else
 		hands.icon_state = lowertext(module.module_type)
+
+
+/**
+ * Updates the observers's screens with cyborg itemss.
+ * Arguments
+ * * item_module - the item being added or removed from the screen
+ * * add - whether or not the item is being added, or removed.
+ */
+/mob/living/silicon/robot/proc/observer_screen_update(obj/item/item_module, add = TRUE)
+	if(!length(observers))
+		return
+	for(var/mob/dead/observe in observers)
+		if(observe.client && observe.client.eye == src)
+			if(add)
+				observe.client.screen += item_module
+			else
+				observe.client.screen -= item_module
+		else
+			observers -= observe
+			if(!length(observers))
+				observers = null
+				break

code/modules/mob/living/silicon/robot/robot_mob.dm

@@ -27,10 +27,6 @@ GLOBAL_LIST_INIT(robot_verbs_default, list(
 	var/atom/movable/screen/lamp_button = null
 	var/atom/movable/screen/thruster_button = null
 
-	/// Used to determine whether the robot has the module menu shown or not.
-	var/shown_robot_modules = FALSE
-	var/atom/movable/screen/robot_modules_background
-
 	// 3 Modules can be activated at any one time.
 	var/obj/item/robot_module/module = null
 	var/module_active = null
@@ -172,11 +168,6 @@ GLOBAL_LIST_INIT(robot_verbs_default, list(
 
 	wires = new(src)
 
-	robot_modules_background = new()
-	robot_modules_background.icon_state = "block"
-	robot_modules_background.layer = HUD_LAYER	//Objects that appear on screen are on layer 20, UI should be just below it.
-	robot_modules_background.plane = HUD_PLANE
-
 	ident = rand(1, 999)
 	rename_character(null, get_default_name())
 	update_icons()
@@ -664,9 +655,6 @@ GLOBAL_LIST_INIT(robot_verbs_default, list(
 
 /mob/living/silicon/robot/proc/reset_module()
 	notify_ai(2)
-
-	shown_robot_modules = 0
-	client?.screen -= robot_modules_background
 	client?.screen -= hud_used.module_store_icon
 	uneq_all()
 	SStgui.close_user_uis(src)
@@ -699,6 +687,8 @@ GLOBAL_LIST_INIT(robot_verbs_default, list(
 
 	status_flags |= CANPUSH
 
+	hud_used.update_robot_modules_display()
+
 //for borg hotkeys, here module refers to borg inv slot, not core module
 /mob/living/silicon/robot/verb/cmd_toggle_module(module as num)
 	set name = "Toggle Module"

code/modules/mob/living/stat_states.dm

@@ -75,7 +75,7 @@
 		update_blind_effects()
 		update_sight()
 		updatehealth("update revive")
-		hud_used?.reload_fullscreen()
+		reload_fullscreen()
 
 	SEND_SIGNAL(src, COMSIG_LIVING_REVIVE, updating)
 

code/modules/mob/mob.dm

@@ -27,6 +27,10 @@
 		viewing_alternate_appearances = null
 	LAssailant = null
 	runechat_msg_location = null
+	if(length(observers))
+		for(var/mob/dead/observe as anything in observers)
+			observe.reset_perspective(null)
+
 	return ..()
 
 /mob/Initialize(mapload)
@@ -600,7 +604,7 @@ GLOBAL_LIST_INIT(slot_equipment_priority, list( \
 	if(.)
 		// Allows sharing HUDs with ghosts
 		if(hud_used)
-			client.screen = list()
+			client.clear_screen()
 			hud_used.show_hud(hud_used.hud_version)
 
 //mob verbs are faster than object verbs. See http://www.byond.com/forum/?post=1326139&page=2#comment8198716 for why this isn't atom/verb/examine()

code/modules/mob/mob_vars.dm

@@ -207,7 +207,7 @@
 	var/datum/input_focus = null
 	/// Is our mob currently suiciding? Used for suicide code along with many different revival checks
 	var/suiciding = FALSE
-	/// Used for some screen objects, such as
+	/// Used for some screen objects
 	var/list/screens = list()
 	/// lazy list. contains /atom/movable/screen/alert only,  On /mob so clientless mobs will throw alerts properly
 	var/list/alerts
@@ -246,7 +246,8 @@
 	var/next_click_modifier = 1
 	/// Tracks the open UIs that a mob has, used in TGUI for various things, such as updating UIs
 	var/list/open_uis = list()
-
+	/// List of observers currently observing us.
+	var/list/mob/dead/observer/observers = list()
 	/// Does this mob speak OOC?
 	/// Controls whether they can say some symbols.
 	var/speaks_ooc = FALSE

code/modules/mob/new_player/new_player.dm

@@ -182,7 +182,10 @@
 				var/period_human_readable = "within [GLOB.configuration.general.roundstart_observer_period] minute\s"
 				if(GLOB.configuration.general.roundstart_observer_period == 0)
 					period_human_readable = "before the round started"
-				to_chat(src, "<span class='notice'>As you observed [period_human_readable], you can freely toggle antag-hud without losing respawnability.</span>")
+				to_chat(src, "<span class='notice'>As you observed [period_human_readable], you can freely toggle antag-hud without losing respawnability, and can freely observe what other players see.</span>")
+				if(!check_rights(R_MOD | R_ADMIN | R_MENTOR, FALSE, src))
+					// admins always get aobserve
+					add_verb(observer, list(/mob/dead/observer/proc/do_observe, /mob/dead/observer/proc/observe))
 			observer.started_as_observer = 1
 			close_spawn_windows()
 			var/obj/spawn_point

code/modules/tgui/modules/ghost_hud_panel.dm

@@ -81,6 +81,9 @@ GLOBAL_DATUM_INIT(ghost_hud_panel, /datum/ui_module/ghost_hud_panel, new)
 
 			GLOB.antag_hud_users |= ghost.ckey
 
+			if(!check_rights(R_MOD | R_ADMIN | R_MENTOR, FALSE))
+				// admins always get aobserve
+				add_verb(ghost, list(/mob/dead/observer/proc/do_observe, /mob/dead/observer/proc/observe))
 
 			ghost.antagHUD = TRUE
 			for(var/datum/atom_hud/antag/H in GLOB.huds)