Control Rig and IK

Ownership boundary

This skill owns skeleton transfer, IK Retargeter setup, retarget poses/operations, procedural solves, contact correction, and animation baking. If a retargeted preview/export is correct but the final pose is wrong, route to unreal-animation-blending. Route capsule movement, root-motion authority, and network prediction to unreal-character-movement.

Route before editing

Read references/system-selector.md.

• Transfer animation between skeletons -> IK Rig + IK Retargeter.
• Retarget live from another component -> Retarget Pose From Mesh.
• Procedurally solve a connected body -> Full Body IK.
• Adjust a few limbs at runtime -> IK Rig node or focused IK nodes.
• Author or repair poses/animation -> Control Rig or FK Control Rig in Sequencer.
• Pin contacts after the base transfer is correct -> goals, Speed Planting, or foot placement.

Do not add IK until the source animation, skeleton assignment, chain map, retarget pose, pelvis, and root behavior have been checked.

Diagnose first when the request is a bug

Read references/symptom-diagnostics.md, then reproduce with one source sequence and one target mesh. Record whether the defect appears in the IK Retargeter preview, an exported sequence, runtime retargeting, or only the final AnimGraph.

Execute

1. Classify the job and isolate the first stage where the pose becomes wrong.
2. Verify source animation, source/target meshes, skeletons, reference poses, and root bones.
3. Define matching retarget roots and chains; inspect every chain mapping.
4. Create and align a dedicated retarget pose.
5. Validate the operation stack from top to bottom, enabling one correction at a time.
6. Add goals/solvers only for contacts or procedural controls that need them.
7. Verify root motion, curves, notifies, runtime component order, LOD, and hidden-mesh ticking.
8. Test representative clips at speed; profile and bake only after the live result is correct.

Load only what applies:

• references/ik-retargeter-setup.md
• references/poses-chains-and-operations.md
• references/root-pelvis-and-contact.md
• references/runtime-retargeting.md
• references/control-rig-and-fbik.md
• references/runtime-foot-placement.md
• references/sequencer-and-baking.md

Required answer format

Return:

1. First broken stage and evidence.
2. Chosen system and rejected alternatives.
3. Required assets, roots, chains, goals, solvers, and pose assumptions.
4. Exact editor/runtime node order and settings to inspect or change.
5. One-change-at-a-time diagnostic procedure.
6. Root-motion, curve, notify, networking, LOD, and performance consequences.
7. Acceptance clips and debug checks.

Hard rules

• Set a retarget root on both IK Rigs, normally the pelvis/hips for bipeds.
• Chain names may differ, but source and target chain intent and boundaries must match.
• Create a new retarget pose for alignment; preserve the default pose as a baseline.
• A Retarget Pose operation belongs first in the operation stack.
• Prefer no FK translation for most chains; change translation mode only for a diagnosed need.
• An IK operation cannot move a chain unless the target chain has an IK goal.
• Fix chains, pose, pelvis, root, and speed before masking foot slide with Speed Planting.
• Ignore Root Lock in Preview is preview-only; export behavior uses export root-lock settings.
• A hidden runtime source mesh must still tick pose and refresh bones.
• Inertialization normally belongs before final IK; runtime IK belongs after the base pose exists.
• Treat Modular Control Rig according to its Experimental UE 5.8 maturity; do not silently make it a shipping dependency.
• Test multiple clips, not only the editor reference pose or one idle.

See references/sources.md for the UE 5.8 source trail.