PC3 Phase 1.2: placeholder avatar asset pack + make the loader actually assemble

assets/avatars/catalog.json referenced 14 GLB files that were never in the
repo, so the avatar system could not load a single avatar. And the loader's
assembly path had never run against a real skeleton -- it called
Skeleton3D.has_bone() (no such method in Godot 4) and hand-copied bones in a
way that dropped the skin binding.

- scripts/tools/gen_placeholder_avatars.gd: generates the pack headlessly via
  GLTFDocument -- one rigged/skinned base body (the full 24-bone canonical
  rig from a T-pose) + 13 primitive attachments. Crude on purpose; real art
  swaps in as a pure content change (catalog paths unchanged).
- assets/avatars/*.glb: the generated pack (checked in).
- avatar_loader.gd: rewrote _parse_glb_as_avatar to lift the skin-bound
  Skeleton3D that generate_scene() already produces, instead of rebuilding it.
  Attachments now mount via BoneAttachment3D to the catalog's mount_bone and
  are actually added to the avatar tree (they were parsed then dropped).
  Fixed the has_bone() crash, the null ARRAY_BONES cast in _retarget_skin,
  and the Array[String] type mismatch on the accessory list.
- smoke_test_avatar_system.gd: replaced the "asserts it fails gracefully
  because the files don't exist" section with a real assembly check --
  Skeleton3D present, full 24-bone rig, canonical bones resolve by name,
  visible body mesh, equipped items mounted to bones. 14/14 from a cold cache.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015jtxAiu5dAW4WxCNdGkrkJ

scripts/smoke_test_avatar_system.gd

@@ -1,14 +1,12 @@
 extends SceneTree
-## Smoke test for the avatar catalog/slot/loadout/system layers.
+## Smoke test for the avatar catalog/slot/loadout/system layers AND the full
+## assembly path against the placeholder GLB asset pack
+## (assets/avatars/*.glb, generated by scripts/tools/gen_placeholder_avatars.gd).
 ##
-## Real .glb model assets don't exist yet (assets/avatars/catalog.json
-## references them, the files themselves are a tracked user to-do -- see
-## the "AGP MVP status" project memory). This test covers everything that
-## doesn't require them (catalog parsing, slot registry, loadout equip/
-## validate, the AvatarSystem orchestrator's autoload wiring) and confirms
-## the one thing that DOES touch missing files -- AvatarLoader.load_base_body()
-## -- fails gracefully (emits load_error, returns null) instead of crashing.
-## Visual rendering itself can't be verified until real assets exist.
+## Covers: catalog parsing, slot registry, loadout equip/validate/round-trip,
+## the AvatarSystem autoload wiring, and load_avatar() actually producing a
+## Skeleton3D with the canonical rig, a visible body mesh, and equipped
+## attachments mounted to the right bones.
 ##
 ## Run with:
 ##     godot --headless --path . --script res://scripts/smoke_test_avatar_system.gd
@@ -55,8 +53,9 @@ func _run() -> void:
 
 	var hair_options: Array[String] = system.get_assets_for_slot("hair")
 	if hair_options.size() > 0:
-		var equip_ok: bool = loadout.add_accessory(hair_options[0])
-		_check("adding a real catalog accessory succeeds", equip_ok)
+		loadout.set_equipment("hair", hair_options[0])
+		_check("equipping a real catalog hair item succeeds",
+			loadout.slots.get("hair") == hair_options[0])
 
 	# 4. Loadout serializes and survives a round trip.
 	var json_str: String = loadout.to_json()
@@ -64,25 +63,45 @@ func _run() -> void:
 	var restored: AvatarLoadout = system.load_loadout_from_json(json_str)
 	_check("loadout round-trips through JSON", restored != null and restored.is_valid())
 
-	# 5. The part that DOES need real files: confirm it fails gracefully
-	# rather than crashing, since assets/avatars/*.glb genuinely don't
-	# exist yet. A crash here would be a real bug; a clean load_error
-	# signal + null return is the correct, already-designed-for behavior.
+	# 5. Full assembly against the placeholder GLB pack.
 	if base_bodies.size() > 0:
-		# A plain bool captured by a lambda is captured BY VALUE in
-		# GDScript -- mutating it inside the closure doesn't propagate to
-		# this outer scope. A single-element Array is the standard
-		# workaround (confirmed the hard way earlier in this same session,
-		# see scripts/smoke_test_network_client.gd's own comment on this).
-		var error_state := [false]
-		var error_handler := func(_msg): error_state[0] = true
+		var errors := [] as Array[String]
+		var error_handler := func(msg): errors.append(msg)
 		system.loader.load_error.connect(error_handler)
-		var result: Node3D = system.loader.load_base_body(base_bodies[0])
+
+		var chest_options: Array[String] = system.get_assets_for_slot("chest")
+		if chest_options.size() > 0:
+			loadout.set_equipment("chest", chest_options[0])
+		var acc_options: Array[String] = system.get_assets_for_slot("accessory")
+		if acc_options.size() > 0:
+			loadout.add_accessory(acc_options[0])
+
+		var avatar: Node3D = system.load_avatar(loadout)
 		system.loader.load_error.disconnect(error_handler)
-		_check("load_base_body against a missing .glb returns null (not a crash)", result == null)
-		_check("load_base_body against a missing .glb emits load_error (not silent)", error_state[0])
+
+		_check("load_avatar returns a node (no load_error: %s)" % str(errors),
+			avatar != null and errors.is_empty())
+		if avatar:
+			var skel := avatar.get_node_or_null("Skeleton3D") as Skeleton3D
+			_check("assembled avatar has a Skeleton3D", skel != null)
+			if skel:
+				_check("skeleton carries the full canonical rig (24 bones)",
+					skel.get_bone_count() == 24)
+				_check("canonical bones resolve by name (Head, LeftHand, RightFoot)",
+					skel.find_bone("Head") != -1
+					and skel.find_bone("LeftHand") != -1
+					and skel.find_bone("RightFoot") != -1)
+				var body_meshes := 0
+				var bone_mounts := 0
+				for c in skel.get_children():
+					if c is MeshInstance3D and c.visible:
+						body_meshes += 1
+					if c is BoneAttachment3D:
+						bone_mounts += 1
+				_check("a visible body mesh is present", body_meshes >= 1)
+				_check("equipped hair + chest are mounted to bones", bone_mounts >= 2)
 	else:
-		print("  SKIP: no base_body entries in catalog to test the failure path against")
+		print("  SKIP: no base_body entries in catalog")
 
 	_finish()