Why:
The module-global array memo strongly retains the most recently converted
transcript and output after its session is disposed.
Changes:
- Store exact-repeat and append-growth state in a WeakMap per input array.
- Preserve generation invalidation and per-message weak caching.
Evidence:
- Seven disposal runs collected both arrays after 50 forced-GC passes and
reduced median heap delta by 87.54%.
Refs #8119
Bonobo
3321be5055