When Codex reports `request_user_input` as unavailable (Default mode), the
Codex skill adapter's Execute-mode-fallback section now explicitly instructs
the agent to append `--text` to `{{GSD_ARGS}}` to activate the workflow's
built-in TEXT_MODE branching. This ensures every AskUserQuestion gate is
handled consistently through the workflow's own text-mode mechanism rather
than ad-hoc plain-text fallback, and eliminates any path to silent-default
selection (#3018 / #3808).
Adds regression test bug-3808-codex-adapter-text-mode-fallback.test.cjs with
typed semantic-flag assertions covering gsd-plan-phase, gsd-discuss-phase,
gsd-execute-phase, and gsd-verify-work.
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
