- Rollback restores the failing location too (a write torn across two
pages, or a read-back mismatch), then the earlier ones; undo failures
are reported in the error. The write loop, checks and rollback move to
cheat_plan_apply() with a memory-ops backend.
- FW split as in CheatRunner: <= 8.20 mdbg only (copy-on-write, private);
> 8.20 physical page only, no mdbg write fallback.
- A physical write must land inside the game's own module (eboot, handle
0, or a module under /app0); Section / module_name / absolute addresses
in a system library are refused.
- Turning a cheat off leaves alone a code cave that overlaps another
enabled cheat of the same title.
- The game is held with SIGSTOP (not ptrace) while the writes land;
SIGCONT on every path. kill(pid, 0) before every write.
- state_set runs under g_apply_lock; the sidecar is read whole (no 4 KiB
cut) and an unreadable one is not rewritten.
- Self-test: fake memory backend failing on every Nth write, on the second
page of a page-straddling write (turning on and off), on the undo
itself, a mismatch, the game exiting mid-apply, and a shared cave.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RxCGb8Asp1A1AQYiv1kbgS
