On codex-cli < 0.137.0 the review.md `codex exec` invocation passed
--dangerously-bypass-hook-trust (added in 0.137) unconditionally and discarded
stderr, so codex exited "unexpected argument" before reading the prompt and the
empty output file was treated as a completed review — a silent degraded review.
- Capability-probe the flag (`codex exec --help | grep`) and apply it via
$CODEX_BYPASS_FLAG only when supported (works fine without it on older CLIs).
- Capture codex stderr to a .err file instead of /dev/null, and replace an empty
output with a diagnostic so a broken reviewer is surfaced (mirrors Cursor/OpenCode).
- Update enh-773 enforcement test to require the capability gate + fail-loud guard
instead of the unconditional flag.
Closes#1115
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>