## Summary
Closes the OIDC loop end-to-end on the BFF side:
- `/auth/callback` now writes the resolved `AuthenticatedUser` into `req.session.user` and waits for `req.session.save()` before redirecting, so the SPA reaches the landing page with a populated session.
- `GET /auth/me` returns the curated public view of the session user (`oid`, `tid`, `username`, `displayName`) or `401 {"error": "unauthenticated"}`. `amr` and other internal claims stay server-side.
- `GET /auth/logout` destroys the BFF session (Redis `DEL`), clears the session cookie, and 302s to Entra's `/oauth2/v2.0/logout` so the IdP-side session is killed too — RP-initiated logout per ADR-0009.
Scope intentionally stops here: the absolute-timeout interceptor (12 h hard ceiling) and the `user_sessions:{userId}` secondary index land in dedicated follow-ups.
## Notable choices
**`req.session.save()` is awaited before the redirect.** Express-session writes to its store on response end; emitting the 302 closes the response before `connect-redis` finishes the write, so without an explicit await the browser can race the SPA into requesting `/me` against a missing key. Awaiting `save()` is the documented fix.
**Logout via `GET`.** Matches `/login` (also `GET`) and keeps the UX a plain anchor / top-level navigation. The CSRF surface is mitigated by `SameSite=Lax` on the session cookie — cross-site subresource requests (`<img src>`, `fetch`) don't carry it. A dedicated CSRF middleware lands with phase-2 security; if we want POST-only logout earlier, easy follow-up.
**`/me` strips `amr`.** The session payload mirrors `AuthenticatedUser` (used internally by the future `@RequireMfa()` guard, ADR-0011), but the SPA only ever needs the curated subset. Mapping happens in the controller — no leak by default.
**Logout URL skips `id_token_hint`.** ADR-0009 mentions it for single-account logout UX, but v1 doesn't persist the `id_token` in the session yet (the encrypted `tokens` blob lands with downstream API support per ADR-0014). Without `id_token_hint`, Entra shows an account picker — the conservative default until token persistence ships.
**Cookie name in logout.** Uses `sessionCookieName()` from `session/session-cookie.ts` so logout clears the same cookie the middleware sets — `__Host-portal_session` in prod, `portal_session` in dev.
## Out of scope (next PRs)
- Absolute-timeout interceptor (12 h hard ceiling, ADR-0010).
- `user_sessions:{userId}` secondary index for admin "logout everywhere".
- Persisting the `id_token` / `access_token` / `refresh_token` blob in the encrypted session (ADR-0014 dependency).
- CSRF middleware (phase-2 security).
- Renaming `ENTRA_POST_LOGOUT_REDIRECT_URI` if we want a distinct post-login redirect target — for now both flows land on the same SPA URL.
## Test plan
- [x] `pnpm nx test portal-bff` → **110/110 pass** (was 99 before this PR; +11 specs across `auth.controller.spec.ts` and `auth.service.spec.ts`).
- [x] `pnpm nx lint portal-bff` → clean.
- [x] `pnpm nx build portal-bff` → webpack compiled successfully.
- [x] Prettier-clean on all touched files.
- [ ] Manual end-to-end smoke test:
- [ ] `/api/auth/login` → Entra → back at `/api/auth/callback` → session cookie set, redirect to SPA.
- [ ] `/api/auth/me` → 200 JSON when authenticated, 401 when anonymous.
- [ ] `/api/auth/logout` → Redis key gone, cookie cleared, lands at SPA via Entra logout.
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Co-authored-by: Julien Gautier <julien.gautier@apf.asso.fr>
Reviewed-on: #112
julien
0464ce3ac8