rootnode-academy/docs/PHASE3A_IDENTITY_AND_INSTRUCTOR_ACCESS.md

# Phase 3A — Identity and Instructor Access

Productionizes identity for RootNode Academy: persistent sessions, real per-instructor accounts
with roles, server-enforced RBAC, CSRF/rate-limiting hardening, and a platform-level audit log.
Builds on `docs/PHASE2B_ADMIN_AND_PLATFORM_DATA.md` (Platform API split, Postgres migration,
first-generation session cookies, admin portal) — read that first if you haven't.

## 1. What changed, in one paragraph

Phase 2B's sessions lived in an in-memory `Map` (gone on every restart) and instructor access
was one shared `ADMIN_PASSWORD` env var (no accountability, no roles, no revocation). Phase 3A
replaces both: sessions are now rows in Postgres (`sessions` table, survive a restart, are
individually revocable), and instructors are real accounts (`instructors` table) with a role —
`owner`, `admin`, or `instructor` — enforced server-side on every `/api/admin/*` route, with a
plain `instructor` further scoped to the cohorts they're assigned to. Every security-relevant
action is now recorded in a platform-level audit log (`audit_events`).

## 2. Schema added

```
instructors         instructor_id, email (unique), display_name, password_hash, role, status,
                     created_at, updated_at, last_login_at
auth_identities      auth_identity_id, instructor_id, provider ('local' today), provider_subject,
                     provider_email, created_at, last_login_at — one 'local' row per instructor;
                     a future OIDC login adds a second row for the SAME instructor_id, no schema
                     change needed then.
sessions             session_id, session_type ('student'|'instructor'), student_id, instructor_id,
                     token_hash (SHA-256 of the bearer token — the raw token is NEVER stored),
                     created_at, last_seen_at, expires_at (absolute), idle_expires_at (sliding,
                     capped at expires_at), revoked_at, metadata
cohort_instructors   cohort_id, instructor_id, role_in_cohort — scopes the plain 'instructor'
                     role; owner/admin never consult this table (global visibility by role alone)
audit_events         audit_event_id, actor_type, actor_id, action, resource_type, resource_id,
                     result, source_ip, metadata, created_at
```

All five are new migrations (`platform/api/migrations/007`–`011`), idempotent (the existing
`schema_migrations` tracking table already guarantees that), and applied automatically on
Platform API startup — no manual migration step. None of Phase 2B's tables
(`students`/`cohorts`/`progress`/`scenario_attempts`/etc.) were touched; all Phase 2B data is
preserved exactly as-is. `sessions.instructor_id` and `cohort_instructors.instructor_id` are
real foreign keys to `instructors` (both tables live in the same Platform API-owned migration
set) — unlike `environments.student_id` in the Provisioner's schema, there's no
cross-service-database reason to keep this one an opaque reference.

## 3. Persistent session design

Browser holds one opaque, CSPRNG bearer token (32 random bytes, base64url) per session, in an
`HttpOnly`, `SameSite=Lax` cookie (`Secure` too, once `COOKIE_SECURE=1`). The server stores only
`SHA-256(token)` — a Postgres dump or backup can't be replayed as a working session, same
principle as password hashing.

Two independent lifecycles (`sessions.session_type`), separate cookie names
(`rn_session`/`rn_instructor`), separate token namespaces — a bug can't confuse a student
session for an instructor one. Each session has:

- **Absolute expiry** (`expires_at`, fixed at creation) — 8h student / 12h instructor by default,
  configurable via `STUDENT_SESSION_TTL_HOURS` / `INSTRUCTOR_SESSION_TTL_HOURS`.
- **Idle expiry** (`idle_expires_at`, slides forward on every authenticated request, never past
  `expires_at`) — 2h default for both, configurable via `*_SESSION_IDLE_HOURS`.

Resolving a session (`sessions.js` `resolveSession`) is one atomic `UPDATE ... RETURNING` that
checks `revoked_at IS NULL AND expires_at > now() AND idle_expires_at > now()` and slides the
idle window forward in the same round trip — no separate read-then-write race.

**Restart behavior:** a Platform API restart no longer logs anyone out — verified in
`platform/test/e2e-phase3a.js` by actually running `docker compose restart api` mid-test and
confirming both an instructor session and a student session still resolve afterward.

**Role/status changes take effect immediately, no revocation needed:** the instructor session
middleware re-fetches the instructor row from Postgres on *every* request rather than trusting
anything cached in the session token — so demoting a role or deactivating an account is live on
the very next request that account makes, with no separate "walk every session and revoke"
step required. Explicit revocation (owner-triggered "revoke all sessions," and automatic on
password change) exists too, for the case where you want to kill an active session immediately
rather than wait for its next request.

## 4. Instructor accounts

`instructors.password_hash` is `scrypt` with a **per-instructor random salt** (Phase 2B's
`admin-auth.js` used one fixed salt because there was exactly one shared password — that's gone,
this is real per-row salting now), stored as `"<salt-hex>:<hash-hex>"`, verified with
`crypto.timingSafeEqual`. No plaintext password ever touches a log line, a database column, or
an API response body (`publicInstructor()` strips `password_hash` before any JSON response).

Bootstrap: `node platform/api/bootstrap-owner.js <email> <name> [password]` — the only supported
way to create the first account, so a fresh deployment never requires editing Postgres by hand.
Refuses to run if an active owner already exists unless the target email is an existing
instructor (the intended zero-owners recovery path).

## 5. Role model (RBAC matrix)

| Action | owner | admin | instructor |
|---|---|---|---|
| Manage instructor accounts (create/edit/deactivate/reset password/revoke sessions) | ✅ | ❌ | ❌ |
| View audit log | ✅ | ✅ | ❌ |
| Create/edit cohorts, create/edit students, assign curriculum | ✅ | ✅ | ❌ |
| Assign an instructor to a cohort | ✅ | ✅ | ❌ |
| View dashboard, cohort list, cohort/student detail, progress | ✅ (global) | ✅ (global) | ✅ (**assigned cohorts only**) |
| Prepare Labs / Destroy Cohort Labs, provision a student's Lab | ✅ (any cohort) | ✅ (any cohort) | ✅ (**assigned cohorts only**) |
| Reset/destroy/view-events by raw environment id | ✅ | ✅ | ❌ — see §6 |

Enforced by `src/rbac.js`, applied per-route in `src/admin-routes.js` — never in the frontend
alone (`frontend/src/admin/*.jsx` hides controls a role can't use, but that's UX; every route
re-checks server-side regardless of what the browser sends or hides). A denied request gets a
flat `403 {"error":"forbidden"}` — no distinction in the response between "wrong role" and
"right role, wrong cohort," and no distinction between "resource doesn't exist" and "you can't
see it," so a 403 never confirms anything about what exists to someone probing.

An unauthenticated request gets `401`, not `403` — the two are kept distinct throughout.

## 6. Cohort-scoped instructor access

`cohort_instructors` maps `instructor_id → cohort_id` (assigned by an owner/admin, never
self-service). A plain `instructor` role's requests to cohort- or student-keyed routes go
through `requireCohortAccess`/`requireStudentCohortAccess`, which check this table;
owner/admin bypass it entirely (global visibility by role alone).

**Deliberate simplification:** the raw `/api/admin/environments/:id/{reset,DELETE,events}`
routes (operate directly on a Provisioner environment id, no cohort context in the URL) stay
owner/admin-only rather than resolving cohort scope from a bare environment id — that resolution
would need an extra Provisioner round trip on every single call. A plain instructor still has
full Lab control, just via the cohort/student-scoped routes (`/cohorts/:id/prepare-labs`,
`/students/:id/environment/provision`, etc.), which already carry the scope check. Upgrade path
if this ever needs to change: add a `student_id`/`cohort_id` lookup to the Provisioner's
`GET /environments/:id` response and extend `requireCohortAccess` to resolve through it.

## 7. Student session hardening

The pick-your-name roster flow is unchanged UX — **this is classroom/pilot identification, not
production authentication.** There is still no password or possession factor at the identity
step; anyone who knows a display name (or can see the roster dropdown) can "become" that
student. What Phase 3A hardens is everything *after* that pick:

- The resulting session is server-controlled and now **persistent** (survives a Platform API
  restart — verified, see §3).
- A student cannot switch identity by editing client state — there's nothing client-side to
  edit; the cookie is `HttpOnly` and opaque.
- Logout revokes the session server-side (`sessions.destroyStudentSession`), not just a
  client-side cookie clear.
- Every Gateway-proxied Lab request (HTTP and WebSocket) re-verifies ownership against the
  session on every request, not just the initial navigation — unchanged from Phase 2B, still
  true here.
- A student session can never call `/api/admin/*` — those routes require an `rn_instructor`
  session in a completely separate cookie/token namespace.
- CSRF (see §8) now also protects student mutating routes (`/api/environment/launch`, `/reset`,
  `/api/progress/record`, `/api/logout`) the same way it protects instructor ones.

**Future upgrade path that doesn't require touching the session system:** one-time student
enrollment codes, parent-issued codes, or institutional SSO would all still terminate in the
exact same `sessions` table and `rn_session` cookie — only the *identity verification step*
before `createStudentSession()` is called would change. This is why the session store was worth
building as a shared, session-type-agnostic module rather than something bespoke to the current
roster-picker.

## 8. CSRF protection

Double-submit cookie pattern, on top of (not instead of) `SameSite=Lax`. On login, a
**non-HttpOnly** cookie is set — `rn_csrf_s` (student) / `rn_csrf_i` (instructor) — deliberately
readable by the frontend's own JS via `document.cookie`. Every state-changing request
(`POST`/`PATCH`/`DELETE`) must echo that value back as an `X-CSRF-Token` header; the server
checks the header matches the cookie it's holding for that same request. A cross-origin
attacker's page can trigger a cookie-carrying request but can't read the cookie's value (browser
same-origin policy) or attach a matching custom header without CORS, which isn't granted to
other origins — so it can never produce a request where the two match.

`GET`/`HEAD`/`OPTIONS` are exempt (nothing to protect). Applied uniformly, including to
`/api/logout` and `/api/auth/logout` — a forged logout is low-severity, but consistent
enforcement was simpler to reason about than a per-route exception.

**One real bug found while testing this:** the Gateway's own progress-relay call
(`platform/gateway/src/server.js` `relayScenarioOutcome`, triggered when a student solves a
scenario inside their Lab) is a server-to-server call to `POST /api/progress/record`, not a
browser one — but it's relaying the browser's own session, so it needs to forward the CSRF
token too. The first fix attempt forwarded only the `X-CSRF-Token` header and still 403'd,
because the double-submit check needs BOTH the cookie *and* a matching header on the request
Platform API actually receives — the fix forwards both.

## 9. Login rate limiting

In-memory sliding window (`src/security.js`), keyed by `ip:email`, max 8 attempts per 5 minutes,
`429` past that. No new dependency — small enough to hand-roll. **Known limitation:** in-memory
means it resets on a Platform API restart and doesn't share state across multiple instances; a
Postgres- or Redis-backed limiter would be the upgrade if this ever needs to survive a restart
or scale beyond one process. Not needed at pilot scale.

## 10. Audit log

`audit_events`, distinct from the Provisioner's `environment_events` (Lab-lifecycle-only).
Records: instructor login success/failure, logout, password change, instructor
created/updated/deactivated, role changes, session revocation, cohort create/update, roster
changes, curriculum assignment, Prepare Labs, Lab reset/destroy, and every `403` authorization
denial (recorded centrally by the RBAC middleware itself, not sprinkled per-route). Never
records plaintext passwords, raw session tokens, Provisioner secrets, or raw routing tokens —
verified by an explicit test assertion (`e2e-phase3a.js` "audit log" case scans recorded
metadata for anything password-shaped). Viewable at `/admin` → Audit (owner/admin only), latest
200 events, no pagination UI yet — pilot-scale, not a SIEM.

## 11. API inventory (new/changed)

```
POST /api/auth/instructor/login       email+password login, rate-limited, no enumeration
POST /api/auth/logout                 revokes the current instructor session
GET  /api/auth/session                current instructor identity (role, etc.)
POST /api/auth/change-password        requires current password; revokes other sessions

POST /api/login                       UNCHANGED route, now backed by persistent sessions
POST /api/logout                      UNCHANGED route, now CSRF-checked + persistent revoke
GET  /api/session/whoami              UNCHANGED — Gateway's ownership-check dependency

GET    /api/admin/instructors             owner only
POST   /api/admin/instructors             owner only
GET    /api/admin/instructors/:id         owner only — includes session list
PATCH  /api/admin/instructors/:id         owner only — role/status/name; blocks removing the last active owner
POST   /api/admin/instructors/:id/revoke-sessions   owner only
POST   /api/admin/instructors/:id/reset-password    owner only — also revokes that instructor's sessions
GET    /api/admin/audit-events            admin/owner
POST   /api/admin/cohorts/:id/instructors owner/admin — assigns an instructor to a cohort
```

Every pre-existing `/api/admin/*` route from Phase 2B still exists at the same path — behavior
unchanged for owner/admin, newly scoped for the `instructor` role (see §5/§6). `/api/admin/login`,
`/api/admin/logout`, `/api/admin/whoami` (the old shared-password routes) are gone — replaced by
the `/api/auth/instructor/*` routes above.

## 12. Frontend/admin changes

- `AdminPortal.jsx` — email+password login form (was a bare password field); nav now
  conditionally shows Instructors (owner) and Audit (owner/admin) tabs; adds an Account tab.
- `InstructorsView.jsx` (new) — create/list/edit instructors, role/status controls, session list
  + revoke-all, password reset.
- `AuditView.jsx` (new) — read-only audit event table.
- `AccountView.jsx` (new) — change-password form for the signed-in instructor.
- `CohortsView.jsx` — create-cohort form and curriculum-assignment button hidden for the
  `instructor` role (server already enforces this; this just avoids showing controls that would
  403).
- `frontend/src/admin/api.js` / `frontend/src/platform/api.js` — both now read the relevant
  `rn_csrf_*` cookie and attach `X-CSRF-Token` on every mutating call.

## 13. Security hardening review (what was checked)

- **Cookie settings** — `HttpOnly` on session cookies, `SameSite=Lax`, `Secure` gated behind
  `COOKIE_SECURE=1` (off by default for local HTTP dev).
- **CSRF** — §8.
- **Login brute force** — §9.
- **Session fixation** — every login issues a brand-new session row (never reuses/upgrades an
  existing token), so there's nothing to "fix" a pre-auth session into.
- **Password handling** — §4.
- **Account enumeration** — identical response for unknown-email and wrong-password (tested).
- **Authorization bypass** — every `/api/admin/*` route re-checks server-side (§5); tested with
  both role-based and cohort-scoped negative cases.
- **Inactive accounts** — rejected at the session-middleware level on every request, not just at
  login (a deactivation takes effect immediately, §3).
- **Revoked sessions** — `resolveSession`'s `WHERE revoked_at IS NULL` makes a revoked session
  fail identically to an expired one.
- **Role downgrade/upgrade session invalidation** — handled by the live re-fetch design (§3),
  not a separate revoke pass.
- **WebSocket authentication** — unchanged from Phase 2A/2B: the Gateway's WS upgrade handler
  re-verifies ownership via the same session-resolution path as HTTP.
- **Gateway ownership checks** — unchanged mechanism, tightened cache TTL (5000ms → 2000ms) so a
  revoked session stops working at the Gateway within a tighter, tested bound.
- **`trust proxy`** — off by default, opt-in via `TRUST_PROXY=1`, so `req.ip` (used for audit
  `source_ip` and rate-limit keys) isn't trivially spoofable via `X-Forwarded-For` unless a real
  trusted proxy is actually in front.

## 14. Test results

- `platform/provisioner/test/run.js` (Phase 1, isolated stack) — **not re-run this phase**: zero
  source changes to `platform/provisioner/` (confirmed via `git diff`), and its own dev compose
  stack collides on port 5433 with the shared `platform/docker-compose.dev.yml` stack used for
  everything else in this phase. Provisioner was still exercised heavily and indirectly through
  every e2e suite below (provision/reset/destroy, concurrent Prepare Labs, cohort-scoped
  operations) — all passing.
- `platform/test/e2e-phase2a.js` — **10/10 passed** (student flow, now under persistent sessions).
- `platform/test/e2e-phase2b.js` — **12/12 passed** (classroom workflow, now under real
  instructor accounts instead of a shared password).
- `platform/test/e2e-phase3a.js` — **21/21 passed**: no-enumeration, CSRF positive+negative,
  rate limiting, role creation, RBAC denial (instructor→owner-only, instructor→admin-only,
  admin→owner-only), cohort scoping (visibility + access), last-owner protection, live
  role/status re-evaluation, password change + old-password rejection + other-session
  revocation, audit log content (including the no-secrets assertion), student session RBAC,
  student logout revocation, and session persistence across a real `docker compose restart api`.
- Real Lab image — rebuilt clean; standalone `--privileged` single-container mode boots and
  serves with zero Platform API/Postgres/Provisioner dependency (verified live).
- Frontend production build — clean, no errors.
- Scenario content / Real Ops bundle / Lab `Dockerfile`/`backend/`/`scripts/` — `git diff`
  against the Phase 2B milestone SHA is empty for all of them: untouched.

## 15. Known limitations

- **Login rate limiting is in-memory, single-process** (§9) — resets on restart, doesn't share
  state across multiple Platform API instances. Fine at pilot scale.
- **Gateway session cache is a 2-second window** — a revoked/expired session can still work at
  the Gateway for up to ~2s after revocation (tightened from 5s in Phase 2B). Platform API
  itself always reflects revocation immediately; this bound is specific to the Gateway's
  whoami-result cache, which exists purely to avoid a Platform API round trip on every single
  proxied Lab byte.
- **No distributed session revocation push** — revoking a session updates Postgres immediately;
  anything holding a *cached* copy of "this session is valid" (only the Gateway does this, and
  only for 2s) catches up on its next cache miss, not instantly.
- **Audit log has no pagination UI** — latest 200 events only. Add pagination if usage ever
  exceeds that being useful.
- **Roster name-picking is still not strong student identity** (§7) — explicitly documented,
  not silently glossed over.
- **`cohort_instructors` role_in_cohort field exists but isn't consulted for finer-grained
  permissions yet** — currently any assignment grants the full `instructor` role's cohort-scoped
  actions; a co-teacher vs. lead-teacher distinction within a cohort would consume this field but
  isn't built.
- **Exam mode's live bookkeeping is still Lab-local** — unchanged from Phase 2B, still a real gap
  for anyone relying on cross-restart exam state.

## 16. Future OIDC path

`auth_identities` (§2) already supports it structurally: a Google/OIDC login would create a
second `auth_identities` row (`provider='google'`, `provider_subject=<their sub>`) pointing at
an existing `instructor_id`, or create a new `instructors` row + `auth_identities` row for a
first-time SSO login. The missing piece is the actual OIDC client flow (discovery, token
exchange, JWT verification) — deliberately **not built this phase**, per the explicit scope
instruction to stop at a documented adapter interface rather than pull in an OIDC client
library and expand scope. `instructors.password_hash` staying nullable (already the case) is
what allows an SSO-only account to exist with no local password at all, whenever that flow is
built.

## 17. Production HTTPS / cookie expectations

Local dev and the current single-VM pilot deployment run over plain HTTP — `COOKIE_SECURE` is
unset (cookies lack `Secure`) and `TRUST_PROXY` is unset by default. Before any real-HTTPS
production deployment: set `COOKIE_SECURE=1` (cookies become HTTPS-only) and, if fronted by a
reverse proxy/load balancer, set `TRUST_PROXY=1` so `req.ip` reflects the real client IP instead
of the proxy's.

## 18. BUILT NOW vs. FUTURE

**Built now:** persistent Postgres-backed sessions (student + instructor), per-instructor
accounts with scrypt password hashing, three-role RBAC enforced server-side, cohort-scoped
instructor access, CSRF double-submit protection, login rate limiting, platform audit log,
owner-safety invariant (never zero active owners), password change with other-session
revocation, `auth_identities` table ready for future OIDC mapping.

**Future (not built):** real OIDC/SSO client flow, multi-instance-safe rate limiting, audit log
pagination/export, cohort_instructors role-in-cohort permission granularity, distributed
(non-Gateway-cache) session revocation push, one-time student enrollment codes /
parent-issued codes, everything already on the Phase 2B "DO NOT BUILD YET" list (capstone
engine, billing, production Proxmox deployment, etc.) — unchanged, still not in scope.