D278 - obscene-injector: decoupled freestanding ELF injection via session kernel R/W

Status: decided.

To measure native Prospero behavior (payload/ps5-native) rather than the PS4 backward-compatibility sandbox (payload/ps4-bc, D276), obSCEne must run inside a native-category process. obscene-injector implements this as a standalone payload ELF (obscene-injector.elf) consuming the session kernel R/W established by kstuff-lite.

The probe and injector remain strictly decoupled:

• The probe never links the injector; the injector never links the probe checks.
• A shared freestanding layer (src/common/freestd.c, src/common/krw.h) factors string/mem helpers out of runtime.c.
• src/injector/krw.c consumes payload_args_t (IPv6 socket pair + pipe buffer) pinned against ps5-payload-dev-sdk.
• src/injector/procctl.c provides ptrace-style process control (attach, get/setregs, step, remote syscall/mmap).
• src/injector/loader.c loads obscene.elf into the target process address space, maps PT_LOAD segments, applies relocations, and sets memory protections.
• src/injector/target.c resolves the target process (foreground app or specified title).
• Linked as plain ET_DYN via link/injector.ld.