The manual PSX_OVERLAY_CODEGEN_VER must be hand-bumped on every emitter change;
when it isn't (e.g. between CPS emitter iterations), a stale-but-cgN DLL is reused
-> the v0.3.0 black screen. Now hash_codegen.cmake hashes the recompiler codegen
sources into a (gitignored) overlay_codegen_hash.h at build time; overlay_api.h
exposes PSX_OVERLAY_CODEGEN_HASH and the cache path becomes gcc/<arch-abi>/cg<N>_<hash>/.
The loader and compile_overlays.py read the same value, so any emitter change
auto-invalidates the cache (old dirs coexist, no stale load). Falls back to hash 0
when the header is absent (fresh checkout) — identical to today's single-cgN path.
Verified: build emits hash 0x347751c1; autocompile + loader both use cg4_347751c1.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Matthew Stanley