Plan readiness review

One question decides everything here: could a competent senior engineer who was not in any of the meetings implement this correctly, without inventing anything? Every check below is a way of attacking that question. Anything an implementer would have to decide for themselves is a gap in the plan, not a detail for later — an implementer's guess is an unreviewed product decision made by whoever happened to pick up the ticket.

Approving a weak plan is the expensive failure mode. A rejected plan costs a day; an ambiguous plan that reaches production costs a rewrite. Bias towards NOT READY and say precisely what would change the verdict.

Phase 0 — Input contract

Before reading anything in depth, state what is under review. If any of these are unknown and cannot be inferred, ask once, in one message, then proceed with what is available and mark the rest as a scope limit in the output.