Development record

.abcd/development/brief/04-surfaces/26-mode.md:97-103 says every refusal of these verbs exits 2 with nothing written and that ending the mode refuses only with no checkout, no home or no root commit. With HOME set to a directory that does not exist, `abcd mode autonomous` and `abcd mode queue <step>` exit 1 with an open error, and `abcd mode back` exits 0, printing both that the record was closed without the store's lock and that there is nothing to end, though no record exists.