Pre-mortem

Assume {bet} has failed, 18 months from now.

Write the history: what we believed, the first ignored warning, the thing we kept doing because it felt like progress, who got hurt, what it cost.

Then the five leading indicators that would have shown this in month three, and the kill rule for each (metric + threshold + date).

Do not end with "but it could still work." If you think it will work, say that in one line at the top, then write the pre-mortem anyway.