On macOS /dev/tty always exists, so '[ -e /dev/tty ]' passed even in agent
harnesses/CI with no controlling terminal — the subsequent read then died
with ENXIO ('Device not configured') and blocked the commit instead of taking
the hook's own non-interactive branch. Probe with '( : < /dev/tty )' — the
exact operation that fails. Both prompt sites fixed; the deliberate asymmetry
preserved (debug keywords warn-and-proceed; secrets fail closed). Verified
both paths from a non-TTY context. Surfaced via the be a11y-gate commit
bypass logged in today's ledger.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
