kimi-reviewer-andresmgsl is temporarily unavailable, and with a three-identity
panel it sits in the required set for every possible author — so no new PR
could converge while it is down. glm-reviewer-andresmgsl takes the seat.
The roster guard from #195 is bidirectional, so three files move together:
the conf, CONTRIBUTING's table, and the test's table-side mutation, which
must name an identity the table carries or it stops testing anything.
Refs #222
