Health survives a door, and experience needs you to be there

Arriving anywhere set health to maximum, so a run cost nothing: walk in,
take what you could, walk out, walk back in whole. Current health now
lives on the character record for the same reason the inventory does --
SimWorld builds a blank player on every instance change, so anything that
must survive a door has to be written down -- and it is banked at every
transfer, every disconnect, and on every item transaction, since a potion
moves an item and hit points in one action.

The hub is where that damage is paid off, at 10% of maximum per second:
about ten seconds from nothing, fast enough not to be a chore and slow
enough to be a decision before walking back in. The dungeon rate is
unchanged, so waiting one out is still not a plan. Regeneration is a
property of the world now rather than a constant.

adopt() no longer touches current health. It is called mid-session by
on_choose_upgrade, and reading health from the record there would snap a
player back to whatever was last written to disk; recompute_max_hp still
clamps downwards so Glass Cannon takes the hit points above the new
ceiling with it. ServerRuntime._adopt_character stays the one place a
record becomes a live player.

Experience is still undivided, but now only among players within
XP_AWARD_RADIUS of the kill -- ten percent past what a player can see, so
anyone who watched it die is inside and someone parked in the entrance
room is not. The death events carry a position for this, and deliberately
do not put it on the wire: encode_events still writes the id alone.

diag_progression covers the whole chain end to end -- wounded in a
dungeon, escaped to the hub with the wound intact, healing there, and
walking back in still hurt -- because a unit test cannot transfer a peer.
Both halves were mutation-tested against it; the unit suite alone missed
the arrival heal entirely.

The Proving Grounds is recorded in the roadmap as a debugging tool that
does not ship: it pays full experience for a boss with 8% health.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tools/diag_progression.gd

@@ -18,6 +18,8 @@ var _step: int = 0
 var _srv: ServerRuntime
 var _account: int = 424242
 var _character: Character
+var _wounded: int = 0
+var _hub_arrival: int = 0
 
 
 func _ready() -> void:
@@ -77,6 +79,11 @@ func _physics_process(_delta: float) -> void:
 			_check(false, "the dungeon had a living enemy to kill")
 			_finish()
 			return
+		# Stand over it. Experience now has a radius, so a kill the player is
+		# nowhere near pays nothing -- which would make this check depend on
+		# where the generator happened to put the enemy.
+		var mine_now: SimPlayer = inst.world.players[Net.LOCAL_PEER]
+		mine_now.pos = victim.pos
 		victim.hp = 1
 		inst.world._damage_enemy(victim, 100)
 		_srv._dispatch_events(inst)
@@ -116,6 +123,68 @@ func _physics_process(_delta: float) -> void:
 		_check(_srv.store.characters_for(_account).size() == before_count,
 			"creating a character inside a dungeon is refused too")
 
+	elif _step == 65:
+		# A kill nobody was near pays nobody. The radius exists because without
+		# it a player parked in the entrance room collected the full experience
+		# for a boss they never saw.
+		var inst := _srv.instance_of(Net.LOCAL_PEER)
+		var far: SimEnemy = null
+		for e in inst.world.enemies.values():
+			if e.alive:
+				far = e
+				break
+		if far == null:
+			_check(false, "a second enemy to kill out of sight")
+		else:
+			var p: SimPlayer = inst.world.players[Net.LOCAL_PEER]
+			p.pos = far.pos + Vector2(SimConfig.XP_AWARD_RADIUS + 400.0, 0.0)
+			var before: int = _srv.store.get_character(_account, _character.id).total_xp
+			far.hp = 1
+			inst.world._damage_enemy(far, 100)
+			_srv._dispatch_events(inst)
+			var after: int = _srv.store.get_character(_account, _character.id).total_xp
+			_check(after == before,
+				"a kill out of range awards nothing (%d -> %d)" % [before, after])
+
+	elif _step == 82:
+		# Health is carried, not reset. Arriving anywhere used to set it to
+		# maximum, which made a run free: walk in, take what you can, walk out,
+		# walk back in whole.
+		var inst := _srv.instance_of(Net.LOCAL_PEER)
+		var p: SimPlayer = inst.world.players[Net.LOCAL_PEER]
+		p.spawn_grace = 0
+		p.hp = int(float(p.max_hp) * 0.4)
+		_wounded = p.hp
+		_check(_wounded > 0 and _wounded < p.max_hp, "the player is wounded")
+
+	elif _step == 84:
+		_srv._send_to_lobby(Net.LOCAL_PEER)
+		var inst := _srv.instance_of(Net.LOCAL_PEER)
+		_check(inst != null and inst.kind == Protocol.InstanceKind.LOBBY,
+			"escaped to the hub")
+		var p: SimPlayer = inst.world.players[Net.LOCAL_PEER]
+		_check(p.hp < p.max_hp, "the wound came with them (%d/%d)" % [p.hp, p.max_hp])
+		_check(absi(p.hp - _wounded) <= 2,
+			"and it is the same wound, not a new number (%d vs %d)" % [p.hp, _wounded])
+		_hub_arrival = p.hp
+
+	elif _step == 88:
+		var inst := _srv.instance_of(Net.LOCAL_PEER)
+		var p: SimPlayer = inst.world.players[Net.LOCAL_PEER]
+		_check(p.hp > _hub_arrival,
+			"the hub is healing it back (%d -> %d)" % [_hub_arrival, p.hp])
+		_check(p.hp < p.max_hp, "but has not finished in four ticks")
+		_srv._send_to_dungeon(Net.LOCAL_PEER)
+
+	elif _step == 89:
+		var inst := _srv.instance_of(Net.LOCAL_PEER)
+		_check(inst != null and inst.kind == Protocol.InstanceKind.DUNGEON,
+			"back into a dungeon")
+		var p: SimPlayer = inst.world.players[Net.LOCAL_PEER]
+		_check(p.hp < p.max_hp,
+			"and walked in still hurt (%d/%d) -- entering is not a heal"
+				% [p.hp, p.max_hp])
+
 	elif _step == 90:
 		# Stop behaving like a bot before the kill. A bot auto-creates a
 		# replacement the instant it sees an empty roster -- correct in play,