22 JIT closure scoping tests covering:
- Basic closure var in map callback + context switch
- Signal + letrec + map (stepper pattern)
- Nested closures (inner lambda sees outer let var)
- Mutual recursion in letrec (is-even/is-odd)
- set! mutation of closure var after JIT compilation
- defisland with signal + letrec + map
- Deep nesting (for-each inside map inside letrec inside let)
All test the critical invariant: JIT-compiled lambdas must use
their closure's vm_env_ref, not the caller's globals.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
giles
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