A core, DMA, rendering, window, or audio error returned before the save was
written, so every completed in-game save since launch was lost. The window now
writes changed bytes on that path too. The diagnostic stays the session error;
a refused or failed write is reported as output. A failed state restore leaves
save memory undefined and is never written. Terminal runs keep the strict rule.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HhfHfHEuzv2AUTd6erW1gU
Machine::save_state and load_state encode the CPU, every RAM, and every device
through Snapshot impls into a versioned, checksummed format. Rejected loads leave
the machine unchanged. The ROM window saves to and loads from one state file
with F5 and F9.
