B1 chunk = any delta (content or reasoning), B2 telemetry plumbing
via explicit _emit pass, B3 orchestration entry gate for independent
stall hedging; N1-N9 advisory fixes merged. Human decisions recorded
in design section 9.
Records what the two Codex review rounds found, which findings held up
under verification, and how each was resolved -- including the one that
changed docs rather than code. Also lists the evidence behind the
completion claim: suite counts, coverage, the 19-minute real-wait Redis
run, and the import contract.