Do you fix payment bugs on staging or directly on the live store?

We reproduce and develop the fix on staging wherever possible, payment code is too risky to edit blind on production. If there’s no staging, we’ll spin one up or work in a safe, isolated way using the gateway’s test mode. The final fix is deployed to live and verified with a small real transaction. We never edit core files, everything is done via plugins, observers, or config, so it survives upgrades.