The stepper's split-tag and steps-to-preview used (list) with append!,
but in the WASM kernel (list) creates immutable List values — append!
returns a new list without mutating, so children accumulate nowhere.
Changed all accumulator initializations to (mutable-list):
- split-tag: cch, cat, spreads
- steps-to-preview: bc-loop inner children, initial call
- result and tokens lists in the parsing setup
Also includes WASM rebuild with append! primitive and &rest fixes.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
giles
58a122a73a