How I use premortems with Claude and Codex (opens in new tab)

I started using premortems for a boring reason: I did not trust the default review question. When I ask a coding agent "does this plan look good?", the answer is usually useful but too polite. It finds reasons the plan can work. It notices a few edge cases. It gives me a clean list of improvements. Fine. But that is not the check I want right before I choose an implementation path, publish an idea, change auth, move data, or let an agent write a large diff. At that point I want a second pass ...