C-side:
* New mode=recovery argv branch in pam_sm_authenticate. Reads the two-line
/var/lib/authforge/recovery/<user> file, argon2_verify against PAM_AUTHTOK,
on match unlinks the file (one-shot) and writes pending(re_enroll=true).
Always returns PAM_IGNORE on failure paths so a missing/wrong code never
blocks normal auth.
* Makefile links -largon2 alongside -lpam.
Daemon-side:
* policy_apply::render_profile renders the recovery line first in the auth
stack with [success=done default=ignore] — successful recovery short-
circuits the rest, missing/wrong code falls through.
* New policy_apply test asserts the recovery line precedes the default
backstop.
Doc:
* pam/TESTING.md adds libargon2-dev to the build prereqs and a new
Smoke test 4 walking through the manual recovery-code flow.
C compile gate (make -C pam) requires libargon2-dev — flagged as a
deferred verification step until a host with the dev package is available.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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