Serialized !… ↔ YAML-like Converter
Serialized input (paste a full Maps URL or raw !… blob)
On paste or decode, this extracts the substring that starts at /data= and ends before the next ? (if any).
YAML-like structure
Encoder recalculates each m as the total number of descendant tokens (nested). Comments are ignored.
Heuristic format. If a real sample doesn’t round-trip, paste it and I’ll adapt the rules or add more type codes.