git:20260913.ed0ec2c to git:20261002.615add9

12 added, 0 removed. Audit A to A.

---

name: animation-blend

description: Use when rendered character poses need weighted locomotion, aim, attack, additive or transition blending while gameplay state, hit timing and displacement ownership remain explicit.

---

# Animation blend

This skill owns **presentation pose composition**, not gameplay state or hit timing. `animation-graph` selects/coordinates animation states/layers; movement owners define displacement policy.

## Compatible displacement columns

| Column | Gameplay displacement owner |

|---|---|

| procedural-loco | locomotion/physics code |

| root-motion | authored root motion consumed by the gameplay movement solver |

| hybrid | published state-dependent ownership with one displacement application |

## Rules

1. Weighted blends/additives/interpolation paint a rendered pose from authoritative animation/gameplay state; they do not extend active hit frames or cancel windows.

2. Blend duration/easing/inertialisation are authored in time/state units appropriate to the runtime, not a universal 2–6 frame fade.

3. Root-motion extraction/application has one explicit gameplay owner. Visual blending must not double-apply root displacement.

4. Aim/look overlays declare mask/weight/reference space and do not silently rotate gameplay facing/collision unless the owning gameplay contract requests it.

5. Foot contact repair delegates to `ik-foot-locking`; blend output remains a source pose rather than a second locomotion solver.

+ ## Corrective layers

+ Procedural corrections applied after the source pose are presentation layers with the same ownership limits. Examples are limb/body interpenetration avoidance, reach or look IK, and prop alignment. They must also be temporally stable:

+ 1. The correction is a continuous function of pose and time. Avoid hard thresholds, snapping to bins or cells, picking whichever sample is deepest, and hard on/off zones. Blend across regions and weight competing samples smoothly.

+ 2. Correct through a degree of freedom that can actually remove the contact. For a contact on the upper segment, rotate the chain about its parent joint rather than pushing an end effector that barely moves that segment. Iterate with bounded gain and no overshoot; a case that does not converge must not alternate between frames.

+ 3. Contact onset is soft enough that brushing contact causes no velocity kink. The allowed residual overlap is an authored tolerance, validated against the project's clipping check.

+ 4. For deterministic clips, corrections may be cached and filtered over time per actor and clip. Invalidate the cache on rig, body or clip changes.

+ 5. Before tuning, attribute jitter by measuring rendered joints with the corrective layer on and off. Fix step thresholds in the source motion separately.

## Accept

Record animation/gameplay state, source clips/layers/weights, displacement owner and resulting pose through transition/interruption cases. Disabling render meshes/blending does not change authoritative hits, cancels or gameplay displacement.

+ For corrective layers, sample joint positions at the presentation rate. Count consecutive-frame acceleration reversals, or another authored jitter metric, with corrections on and off, alongside the penetration check. Neither metric may regress.