pointbreak Phase 1 (spec 2026-07-11, §1.3) needs 'a.b.c' → ['a','a.b','a.b.c']. .list.head/.slice take Python ints only, so per-row variable-length prefixes are inexpressible; worked around construction-side in polars (int_ranges + explode + list.head(expr)). Marker: 'ma-gap' in pointbreak bronze.py.
pointbreak Phase 1 (spec 2026-07-11, §1.3) needs 'a.b.c' → ['a','a.b','a.b.c']. .list.head/.slice take Python ints only, so per-row variable-length prefixes are inexpressible; worked around construction-side in polars (int_ranges + explode + list.head(expr)). Marker: 'ma-gap' in pointbreak bronze.py.