## Per-Compound Iteration Stepper

Each loop/split compound gets its own stepper in the header bar

Loop with iteration stepper — iteration 3 of 5
LOOP
3 / 5
transform
TRANSFORM
3ms
✓
to:http:api
TO
45ms
✓
log:result
LOG
1ms
✓

### Nested Loops

Each compound level has its own independent stepper

Outer loop (iteration 2/3) containing inner split (branch 1/4)
LOOP
2 / 3
setBody
SET_BODY
✓
SPLIT
1 / 4
to:kafka
TO
✓

### Stepper Behavior

- Independent per compound — outer loop at iteration 2, inner split at branch 1
- Overlay updates per-compound — stepping the loop re-renders its children's execution data for that iteration
- CHOICE shows which branch was taken — no stepper, just highlights the taken branch
- Keyboard — when a compound is focused/hovered, left/right arrow keys step through iterations
- Detail panel syncs — selecting a processor inside a loop shows that iteration's data