Development record

The drive section of `35-drain.md` (lines 193-340) states the walls, a credential variable and a start from an agent's session as refusals, and its appendix leaves exit codes to the prose. It never states the default cap of eight lanes (`driveDefaultCap`, against no cap on the bare verb); `--yes` and the refusal with no terminal to ask at; exit 3 for a second drive and for a drive stopped, stopped short or holding an issue back, exit 2 for a failed check, exit 130 for the second signal; the refusals for an agent runner not enabled or not admitted and for a role pinned to the host; or the `--until` forms (a date read as the end of that day, or an RFC 3339 instant) and the refusal of a time already past. `abcd drain --help` and `commands/drain.md` state each.