#5031 "Forged-request protection: SameSite cookie, per-session CSRF token on every non-GET, HTMX header". A page on another site could make a logged-in browser POST to Steward with the session cookie attached. - steward/auth/csrf.py: a per-session token, checked in one before_request for every POST/PUT/PATCH/DELETE (header X-CSRF-Token or form field csrf_token, constant-time compare). The bearer-authenticated host-agent ingest is exempt; /mcp never reaches Quart. - Every POST form renders {{ csrf_field() }}; base.html carries the token in a meta tag and adds it to every HTMX request; the dashboard's fetch() calls send it. - The session cookie is SameSite=Lax; login issues a fresh token. - PUBLIC_BASE_URL is now loaded from Settings at startup (it was only set when Settings → General was saved). - tests/test_csrf.py: refusal, acceptance, rotation, the ingest exemption, and a guard that every POST form in the templates carries the field. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>