nx_pabi_gate.nx

nx_pabi_gate.nx -- gate for the portable syscall-ABI seam (R1 kernel: one forge file op, two OSes). T1 LINUX roundtrip: write "FORGE-PABI-2026" -> read back byte-exact (host kernel path). T2 NISHIOS roundtrip: same op in a fresh sovereign block-VFS image -> read back byte-exact (NO Linux kernel -- the NishiOS-native path via nx_vfsblock_lib). T3 ★CROSS-SUBSTRATE IDENTITY: the LINUX result and the NISHIOS result are BYTE-IDENTICAL -- the SAME forge-level file operation produced the SAME bytes on the host kernel AND on NishiOS. This is the portability seam PROVEN: forge is no longer bound to one OS. T4 NEG: read an absent path on NISHIOS -> -1 (no fabricated content). license_tier: ORIGINAL expect_exit: 0