v3 VM + GC

Heap-backed values

• arrays, maps, closures are heap objects
• scalars stay immediate

Closure execution model

• OpMakeClosure captures current environment
• call uses lexical parent chain

Mark-and-sweep

• mark from stack + active frame/env roots
• traverse arrays, maps, closures
• sweep removes unmarked
• reset marks each collection

Critical correctness rules

• mark map keys as well as values
• mark captured environments
• recursive mark idempotence via visited/marked bit

Runtime safety

• non-closure call errors
• invalid key/index/type operations at runtime
• bounds/type checks remain runtime responsibility

Debug checks

• same program should leak fewer objects after GC trigger
• closure call behavior confirms captured references retained