nx_xor_arena.nx

nx_xor_arena.nx -- demo of the arena-based architecture-neutral library pattern that resolves F5 (cross-architecture library + orchestrator collision) per docs/NISHI_LANG_FRICTION_CATALOG.md. Why this exists: F5 demonstrated that crypto libraries importing `nx_syscalls.nx` for sys_mmap become RV64-pinned, preventing composition with x86_64 socket smokes. The CANONICAL RESOLUTION is the arena pattern shipped in `nx_arena_types.nx` (zero-syscall, caller-owned buffers per cardinal user-owns-every-bit). This module is a tiny working proof: a library that does real work (XOR two buffers, allocate the output via arena) WITHOUT importing any syscall file. The orchestrator provides the arena's backing buffer using whichever architecture's syscall layer matches the target. What this proves: - Library is architecture-neutral (no syscall import). - Library composes cleanly with x86_64 socket code in one compilation unit (see bench/nx_arena_x86_64_compose_smoke.nx). - Library equally composes with RV64 + qemu (caller swaps the syscall layer for the arena backing buffer; library code is unchanged). The crypto-stack refactor to follow this pattern (nx_x25519 + nx_chacha20 + nx_poly1305 + nx_sha256 etc. taking *NxArena instead of calling sys_mmap directly) is a 5-10 turn arc. This module documents the target pattern + provides a proof- of-correctness for the cross-architecture compose so the refactor has a concrete checkpoint to validate against. nx_capability_claims: needs: [arena_alloc, pointer_arithmetic] provides: [xor_buf_arena] safety: [no_syscall, no_floating_point, target_agnostic, bit_equal_reproducible] verdict: [no_silent_failure (arena oom returns null)] license: ORIGINAL kind: racing_crew_specialist