Fixes the silent miscompile under SX_SERVING_JIT=1 (http-listen + cek_run_with_io):
a perform inside a native HO-primitive callback (map/filter/reduce/for-each)
unwound the native loop, corrupting the stack so the next CALL_PRIM read garbage
args (map/rest/drop). (A) call_closure_reuse resolves callback IO inline in
serving mode so the loop survives; (A') resume_vm restores _active_vm; (B)
register_jit_hook resolve_loop falls back to CEK on resume error (no 500).
Repro 9/9 (hosts/ocaml/bin/repro_jit_resume.ml); conformance unchanged 4834/1110.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
giles
d122aed0cb