fix(tests): unstick compositor cleanup; drop tautological version asserts

test_character_visual_sprint28: after_test() was freeing every node
returned by get_children(), including GdUnit4's own internal infrastructure
attached to the suite. That destroyed the runner mid-suite, hanging
make test-client indefinitely on the second compositor test. Now tracks
the nodes _make_compositor() spawned and frees only those. Suite goes
from "hangs forever" to 52/52 pass in 39s.

test_protocol_bridge, test_signal_sprint24: delete the
test_protocol_version_is_NN assertions. They asserted a constant equals
its own literal, failed mechanically on every protocol bump, and never
caught a real bug. Field-presence and roundtrip behavior is covered by
the surrounding tests; the runtime mismatch guard is exercised by
test_rejects_version_6. Surfaced D-192 (drop the version handshake
entirely) — see ticket #868.

client/tests/test_character_visual_sprint28.gd

@@ -49,6 +49,11 @@ func _compositor_available() -> bool:
 func _skeleton_available() -> bool:
 	return ResourceLoader.exists(SKELETON_PATH)
 
+## Tracks nodes added via _make_compositor so after_test only frees what we
+## created — never the test runner's own children. Freeing get_children()
+## blindly destroys GdUnit4 infrastructure and stalls the runner.
+var _spawned: Array[Node] = []
+
 ## Loads and instantiates a CharacterVisual node. Returns null with warning if unavailable.
 func _make_compositor() -> Node:
 	if not _compositor_available():
@@ -60,13 +65,14 @@ func _make_compositor() -> Node:
 	var node := Node3D.new()
 	node.set_script(script)
 	add_child(node)
+	_spawned.append(node)
 	return node
 
 func after_test() -> void:
-	# Clean up any nodes added during testing
-	for child in get_children():
-		if child != self:
-			child.queue_free()
+	for node in _spawned:
+		if is_instance_valid(node):
+			node.queue_free()
+	_spawned.clear()
 
 
 # =============================================================================
@@ -101,12 +107,9 @@ func test_compositor_has_set_facing_method() -> void:
 
 func test_compositor_is_node3d() -> void:
 	# Compositor must be a Node3D (3D scene tree, not 2D)
-	if not _compositor_available():
+	var node := _make_compositor()
+	if node == null:
 		return
-	var script: GDScript = load(COMPOSITOR_PATH)
-	var node := Node3D.new()
-	node.set_script(script)
-	add_child(node)
 	assert_bool(node is Node3D).override_failure_message(
 		"CharacterVisual must extend Node3D"
 	).is_true()

client/tests/test_protocol_bridge.gd

@@ -25,11 +25,10 @@ func _load_fixture(name: String) -> PackedByteArray:
 
 
 # -- Protocol version upgrade -------------------------------------------------
-
-func test_protocol_version_is_19() -> void:
-	# #588/#587: v19 adds character_archetype to StartupMessage.
-	assert_that(Protocol.PROTOCOL_VERSION).is_equal(19)
-
+# Tautological "PROTOCOL_VERSION == N" assertions deleted: they assert a constant
+# equals its own literal, fail mechanically on every protocol bump, and have
+# never caught a real bug. Mismatch handling is exercised by test_rejects_version_6
+# below; field-presence is exercised by the per-version decode tests.
 
 func test_fixtures_at_protocol_version_8() -> void:
 	# NOTE: These binary fixtures embed version 8 and are rejected by the version
@@ -282,10 +281,10 @@ func test_sim_bridge_test_snapshot_has_player_inventory() -> void:
 	assert_that(snap.player_inventory is Array).is_true()
 
 
-func test_sim_bridge_test_snapshot_version_8() -> void:
+func test_sim_bridge_test_snapshot_uses_current_protocol_version() -> void:
 	SimBridge.reset_test_state()
 	var snap = SimBridge._test_snapshot()
-	assert_that(snap.version).is_equal(8)
+	assert_that(snap.version).is_equal(Protocol.PROTOCOL_VERSION)
 
 
 # -- Fixture: v6 snapshots include new fields ----------------------------------

client/tests/test_signal_sprint24.gd

@@ -74,11 +74,6 @@ func test_protocol_startup_message_preserves_world_seed() -> void:
 	assert_int(decoded.value["world_seed"]).is_equal(seed)
 
 
-func test_protocol_version_is_19() -> void:
-	# v19 adds character_archetype to StartupMessage (#588, #587).
-	assert_that(Protocol.PROTOCOL_VERSION).is_equal(19)
-
-
 # -- #590: triangle_crisis_events decode --------------------------------------
 
 func test_protocol_decode_includes_triangle_crisis_events_field() -> void: