# RC46 · Selective movement rebuild

## Principle

The exercise defines the movement truth. Sheet names, pose names and old atlas mappings are not authoritative.

RC46 is the first runtime-affecting pass after RC44/RC45. It does **not** generate images. It applies the first safe movement rules to the existing atlas and only activates MediaPipe landmarks where confidence and movement risk allow it.

## What changed

### Active sequence rebuilds

- `lateral-line-hops`: rebuilt around a bilateral foot-pair anchor. Old single left/right foot locks were replaced by `footCenter`/foot-pair intent to prevent random foot selection.
- `pull-up` and `chin-up`: treated as locked bar keyframe sequences. `barTop` remains the anchor; no free body glide.
- `buddy-hamstring-curls`: knee pivot locked manually. MediaPipe candidate remains inactive because the partner/floor frames have poor confidence.
- `box-jump` and `seated-box-jump`: explicit prop phases and foot-pair anchors added. MediaPipe runtime activation is blocked on low-confidence frames.
- `med-ball-slam`: object/hand binding metadata added.
- `chest-pass` and `rotational-throw`: marked as review-hold because current candidates reuse medball-slam frames and are not true exercise movements.
- `carioca-shuffle` and `lateral-power-shuffle`: split into different footwork semantics so crossover and non-crossover foot logic are not merged.
- `mountain-climber`: active-leg phase metadata added.

### Selective MediaPipe runtime activation

MediaPipe runtime landmarks are activated only for selected safe/green movement groups:

- `lateral-line-hops`
- `bodyweight-squat`
- `hamstring-bridge`
- `pull-up`
- `chin-up`

Special props, partner exercises and weak detections stay on alpha/manual landmarks.

## Review tools

Open:

```text
/tools/movement_rebuild_lab.html?v=rc46
```

Test the pass runtime:

```text
/preview.html?v=rc46&motionlab=1#pass
```

## QA note

Chromium/Playwright screenshots were not produced in the sandbox. Static QA was rendered by WeasyPrint → PDF → PNG.