nx_strap_emit.nx

nx_strap_emit.nx -- S-MODE TRAP DELEGATION + sret (X-PAGE-STRAP-001). The real-OS trap path: instead of every trap going to the M-mode monitor, an exception is DELEGATED (medeleg) to the S-mode kernel, which handles it at stvec and returns with sret. Sequence: M-mode installs mtvec(=M handler) + stvec(=S handler) + medeleg + drops to U-mode (mret, MPP=U); the U program ecalls; with the ecall-from-U bit set in medeleg the trap vectors to the S-MODE handler (stvec), which confirms scause==8, prints "STRAP", advances sepc+4, and sret's back to U; the U program then halts (finisher) -- reaching the finisher PROVES sret returned. With medeleg=0 (the gate's control) the trap goes to the M-mode handler instead -> "MTRAP", no STRAP. medeleg (argv[1]) -- default 0x100 (delegate ecall-from-U, cause 8). out-path (argv[2]). Sovereign, no gcc/.sh. license_tier: ORIGINAL