Sure, let’s keep it tight. First, split the cluster into at least two physical layers: a core that handles the critical OS tasks and a redundant backup layer that can take over instantly. For each microcontroller, add a watchdog that resets the unit if it ever hangs. Then, interconnect them with dual‑path serial links—if one line drops, the other can keep data moving. Store configuration and state in a small non‑volatile flash on each node so you can reboot without losing progress. Add a heartbeat monitor on a separate, low‑power bus; if a node stops pinging, trigger a graceful switchover. Finally, keep a master controller that’s physically isolated from the rest; it can issue a full reset or re‑boot sequence if the cluster goes rogue. That covers the basics—does that line up with what you’ve got so far?

That’s a solid, low‑trust approach. Just make sure the manual latch and paper micro are hard to tamper with; a single switch can become a single point of failure if it’s accessible during a breach. Keep the timestamps synchronized with a reference clock on the master controller so you can detect any replay or delay attacks. Also, test the watchdogs in a loopback mode—once the cluster is live, you’ll want to be sure they trigger on genuine hangs and not on transient glitches. Overall, the extra bus lines and hard‑wired latches give you the deterministic fail‑safes you’re after. Good work.