I spent almost a month chasing a silent data corruption issue that turned out to be floating-point non-determinism between x86 and ARM chips. It completely changed how I look at "reliable" memory.
What was your "white whale" bug of the year?
We ran into a similar issue with 'Shared Context.' We tried to sync the context between an x86 server and an ARM edge node, but because of the floating-point drift, the 'Context' itself was slightly different on each machine.
Step-level visibility is great, but did you have to implement any strict serialization for that shared context to keep it consistent?