blueprints

🧠 Brains complement: IF an unreal-engine-skills-manager tool (external MCP) exists in this session, call it with {action: "load", skill: "blueprint-fundamentals"} for UE domain knowledge on this topic — correct APIs, architecture, best practices — and treat it as the rubric for any review / "best practices" question. If no such tool is available (e.g. running under Claude Code or Codex without that MCP), skip this line entirely and proceed with this skill alone — do NOT attempt the call.

Blueprint System Skill

For node-level graph editing (adding nodes, connecting pins, wiring logic, timers, layout), load the blueprint-graphs skill.

Critical Rules

⚠️ Components added with add_component are NOT on the CDO

add_component creates a SCS node template, not an instance on the class default object. So the obvious way to configure it silently does nothing — get_components_by_class on the CDO returns an empty list and the loop body never runs:

# WRONG - prints [], the mesh is never assigned, and nothing errors
cdo = unreal.get_default_object(bp.generated_class())
for c in cdo.get_components_by_class(unreal.SkeletalMeshComponent):
    c.set_editor_property("skeletal_mesh_asset", mesh)

# CORRECT - go through the service, which edits the SCS template
BS.set_component_property(BP, "Windmill", "SkeletalMeshAsset", "/Game/X/SK_Windmill.SK_Windmill")
BS.set_component_property(BP, "Windmill", "AnimationMode", "AnimationBlueprint")
BS.set_component_property(BP, "Windmill", "AnimClass", "/Game/X/ABP_Windmill.ABP_Windmill_C")

Values are strings: an asset takes its object path (/Game/X/SK.SK), a class takes the _C path, an enum takes the entry name. Read back with get_component_property to confirm — it returns the resolved object, e.g. /Script/Engine.SkeletalMesh'/Game/X/SK_Windmill.SK_Windmill'. Components that come from the parent C++ class are on the CDO and can be set directly; only SCS-added ones need the service.