GitHub's check on f043db35: bookspec's `rules_md_carries_every_id`
refuses "DECISION" in docs/spec/rules.md (bookspec's word is CHOICE,
P13 step 3); P4's B-43 wrote "DECISION D-47" twice. The portable
macOS job: `a_socket_with_no_other_end_names_no_process_and_isnt_us`
uses `SOCK_CLOEXEC` and Linux's answer for a peerless socket; it is
gated to Linux, which is what it tests.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp