Nothing is awake and watching when the party arrives

Room 0 is left empty so that arriving is not an ambush, but that only
ever covered room 0. An enemy in a neighbouring room within aggro range
and in sight of the entrance woke the moment you arrived -- in one run
in eight before the tunnels were widened, and in three runs in eight
after, because wider tunnels mean more open ground and more lines of
sight. Measured over 200 runs: 25 before, 75 after. A screenshot of an
arrival with enemies visibly in range is what prompted counting.

Room enemies that would be awake on arrival -- within their aggro range
of the entrance with nothing in the way, the same two questions aggro
asks -- are now skipped. That is about one enemy in sixteen. Clearing
everything within aggro range regardless of sight would have removed
nearly a third, which is a different dungeon rather than a fixed one.
The skipped enemy's dice have already been rolled, so every other enemy
stands exactly where that seed always put it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/integration/test_dungeon_flow.gd

@@ -211,3 +211,26 @@ func test_boss_rush_leaves_the_tunnels_empty_too() -> void:
 	var run := Instance.make_dungeon(2, 4242, 3)
 	GameOpts.boss_rush = false
 	assert_eq(_tunnel_enemies(run).size(), 0)
+
+
+func test_nothing_is_awake_and_watching_when_the_party_arrives() -> void:
+	# Room 0 is left empty so that arriving is not an ambush, but that only ever
+	# covered room 0. With tunnels widened, three runs in eight had an enemy in
+	# a neighbouring room within aggro range and in sight of the entrance.
+	var watching := 0
+	for s in range(1, 120):
+		var run := Instance.make_dungeon(2, s * 7919, 1 + (s % 3))
+		for e in run.world.enemies.values():
+			if e.pos.distance_to(run.world.spawn_point) <= e.def.aggro_range \
+					and run.world.map.has_line_of_sight(e.pos, run.world.spawn_point):
+				watching += 1
+	assert_eq(watching, 0, "%d enemies could see the entrance at the moment of arrival" % watching)
+
+
+func test_clearing_the_entrance_leaves_the_rest_of_the_dungeon_alone() -> void:
+	# It skips the few enemies that would be awake on arrival and nothing else:
+	# the dungeon keeps nearly all of its population.
+	var total := 0
+	for s in range(1, 40):
+		total += Instance.make_dungeon(2, s * 7919, 1).world.enemies.size()
+	assert_gt(float(total) / 39.0, 9.0, "a depth-1 dungeon still has a dungeon's worth of enemies")