- PHI strict: default ON, disable via HAKO_VM_PHI_STRICT=0 (alias NYASH_VM_PHI_STRICT=0)
- LoopForm: insert initial header PHI (preheader input) and rebind vars before condition; seal updates PHI inputs; avoid duplicate PHIs by replace
- MIR interpreter: add HAKO_VM_MAX_STEPS (alias NYASH_VM_MAX_STEPS) fail-fast budget to prevent infinite loops
- StringBox.lastIndexOf implemented (rfind, returns -1 when not found) in VM handlers
- Smokes: add strict/core/vm_phi_strict_smoke.sh (opt-in); quick remains green 120/120
- Docs: lang/src/vm/README.md and CURRENT_TASK.md updated with PHI strict policy and step budget