feat: guest passage — slip through as a wanderer

POST /auth/guest mints a real user row (wanderer-<4 hex>, collision
retry, unusable random password) and issues the normal session cookie,
per-IP rate limited at 5/hour. EnterPage gains the guest action;
the séance shows a dismissible claim-a-name note for wanderer- users.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

backend/app/routes/auth.py

@@ -1,3 +1,4 @@
+import secrets
 from datetime import datetime, timezone
 
 from fastapi import APIRouter, Cookie, Depends, HTTPException, Request, Response, status
@@ -9,6 +10,7 @@ from app.deps import SESSION_COOKIE_NAME, get_current_user
 from app.models.auth_session import AuthSession, SESSION_TTL, generate_session_token, hash_token
 from app.models.unlock import UnlockRecord
 from app.models.user import User
+from app.rate_limit import RateLimiter, resolve_client_ip
 from app.schemas import LoginRequest, RegisterRequest, UserOut
 from app.security import hash_password, verify_password
 
@@ -16,6 +18,15 @@ router = APIRouter(prefix="/auth", tags=["auth"])
 
 _DUMMY_PASSWORD_HASH = hash_password("dummy-password-for-timing-safety")
 
+# Guest creation writes a real user row per call — without a per-IP cap a
+# single client could fill the users table. resolve_client_ip (not the raw
+# socket peer) because internet traffic arrives via the Cloudflare Tunnel.
+guest_limiter = RateLimiter(max_requests=5, window_seconds=3600)
+
+# 4 hex chars = 65k names; a full retry budget failing means the wanderer
+# namespace is effectively exhausted, not that we got unlucky.
+_GUEST_NAME_ATTEMPTS = 8
+
 
 @router.post("/register", response_model=UserOut, status_code=status.HTTP_201_CREATED)
 async def register(payload: RegisterRequest, db: AsyncSession = Depends(get_db)):
@@ -34,6 +45,63 @@ async def register(payload: RegisterRequest, db: AsyncSession = Depends(get_db))
     return user
 
 
+@router.post("/guest", response_model=UserOut, status_code=status.HTTP_201_CREATED)
+async def guest(
+    request: Request,
+    response: Response,
+    db: AsyncSession = Depends(get_db),
+):
+    client_ip = resolve_client_ip(
+        request.headers, request.client.host if request.client else None
+    )
+    if not guest_limiter.allow(client_ip):
+        raise HTTPException(
+            status.HTTP_429_TOO_MANY_REQUESTS,
+            "the veil admits only so many wanderers — return later",
+        )
+
+    for _ in range(_GUEST_NAME_ATTEMPTS):
+        username = f"wanderer-{secrets.token_hex(2)}"
+        existing = await db.scalar(select(User).where(User.username == username))
+        if existing is None:
+            break
+    else:
+        raise HTTPException(
+            status.HTTP_503_SERVICE_UNAVAILABLE,
+            "the mist is too crowded — try again",
+        )
+
+    # A guest is a real user: the password is random and never disclosed, so
+    # the row is unreachable via /auth/login but works everywhere else.
+    user = User(
+        username=username,
+        password_hash=hash_password(secrets.token_urlsafe(32)),
+    )
+    db.add(user)
+    await db.commit()
+    await db.refresh(user)
+
+    raw_token, token_hash = generate_session_token()
+    session = AuthSession(
+        user_id=user.id,
+        token_hash=token_hash,
+        expires_at=datetime.now(timezone.utc) + SESSION_TTL,
+    )
+    db.add(session)
+    await db.commit()
+
+    # Same dual-scheme cookie rule as /auth/login (https tunnel vs LAN http).
+    response.set_cookie(
+        SESSION_COOKIE_NAME,
+        raw_token,
+        httponly=True,
+        samesite="lax",
+        secure=request.url.scheme == "https",
+        max_age=int(SESSION_TTL.total_seconds()),
+    )
+    return user
+
+
 @router.post("/login", response_model=UserOut)
 async def login(
     payload: LoginRequest,

backend/tests/test_auth_guest.py

@@ -0,0 +1,60 @@
+import pytest
+
+import app.routes.auth as auth_module
+
+
+@pytest.fixture(autouse=True)
+def _reset_guest_limiter():
+    # The limiter is module-level state; a previous test's hits would bleed
+    # into the next one's per-IP budget.
+    auth_module.guest_limiter._hits.clear()
+    yield
+
+
+@pytest.mark.asyncio
+async def test_guest_creates_wanderer_and_cookie_works_on_me(client):
+    response = await client.post("/auth/guest")
+    assert response.status_code == 201
+    body = response.json()
+    assert body["username"].startswith("wanderer-")
+    assert "password" not in body
+    assert "qm_session" in response.cookies
+
+    me_resp = await client.get("/auth/me")
+    assert me_resp.status_code == 200
+    assert me_resp.json()["username"] == body["username"]
+
+
+@pytest.mark.asyncio
+async def test_guest_cannot_login_with_any_password(client):
+    response = await client.post("/auth/guest")
+    username = response.json()["username"]
+    login_resp = await client.post(
+        "/auth/login", json={"username": username, "password": "anythingatall"}
+    )
+    assert login_resp.status_code == 401
+
+
+@pytest.mark.asyncio
+async def test_guest_rate_limit_fires_per_ip(client):
+    for _ in range(5):
+        response = await client.post("/auth/guest")
+        assert response.status_code == 201
+    response = await client.post("/auth/guest")
+    assert response.status_code == 429
+
+
+@pytest.mark.asyncio
+async def test_guest_username_collision_retries(client, monkeypatch):
+    taken_resp = await client.post("/auth/guest")
+    taken = taken_resp.json()["username"].removeprefix("wanderer-")
+
+    # First attempt collides with the existing wanderer; the retry must land
+    # on the fresh suffix instead of erroring out.
+    suffixes = iter([taken, "f4ee"])
+    monkeypatch.setattr(
+        auth_module.secrets, "token_hex", lambda n: next(suffixes)
+    )
+    response = await client.post("/auth/guest")
+    assert response.status_code == 201
+    assert response.json()["username"] == "wanderer-f4ee"

frontend/src/api.ts

@@ -40,6 +40,10 @@ export function login(username: string, password: string): Promise<User> {
   })
 }
 
+export function guest(): Promise<User> {
+  return request<User>('/auth/guest', { method: 'POST' })
+}
+
 export function logout(): Promise<void> {
   return request<void>('/auth/logout', { method: 'POST' })
 }

frontend/src/i18n/en.json

@@ -79,7 +79,8 @@
     "switchToRegister": "no name in the registry? first contact →",
     "switchToLogin": "already carved your name? reconnect →",
     "failed": "the veil rejected you: {{message}}",
-    "smallPrint": "your medium handle is only ever stored on this server"
+    "smallPrint": "your medium handle is only ever stored on this server",
+    "guest": "slip through as a wanderer"
   },
   "seance": {
     "modes": {
@@ -272,6 +273,11 @@
         "entity": "entity",
         "jitter": "jitter"
       }
+    },
+    "wanderer": {
+      "note": "your contacts fade with the mist —",
+      "claim": "claim a name to keep your codex",
+      "dismiss": "let the mist take it"
     }
   },
   "codex": {

frontend/src/i18n/es.json

@@ -79,7 +79,8 @@
     "switchToRegister": "¿sin nombre en el registro? primer contacto →",
     "switchToLogin": "¿ya grabaste tu nombre? reconectar →",
     "failed": "el velo te rechazó: {{message}}",
-    "smallPrint": "tu nombre de médium solo se guarda en este servidor"
+    "smallPrint": "tu nombre de médium solo se guarda en este servidor",
+    "guest": "escabúllete como errante"
   },
   "seance": {
     "modes": {
@@ -272,6 +273,11 @@
         "entity": "entidad",
         "jitter": "fluctuación"
       }
+    },
+    "wanderer": {
+      "note": "tus contactos se desvanecen con la niebla —",
+      "claim": "reclama un nombre para conservar tu códice",
+      "dismiss": "deja que la niebla se lo lleve"
     }
   },
   "codex": {

frontend/src/pages/EnterPage.css

@@ -257,6 +257,38 @@
   cursor: wait;
 }
 
+.enter-guest {
+  display: block;
+  width: 100%;
+  margin-top: 0.9rem;
+  font-family: 'Cinzel', serif;
+  font-size: 0.72rem;
+  letter-spacing: 0.2em;
+  text-transform: uppercase;
+  color: rgba(216, 230, 221, 0.6);
+  background: transparent;
+  border: 1px dashed rgba(216, 230, 221, 0.25);
+  border-radius: 0;
+  padding: 0.65rem 1rem;
+  cursor: pointer;
+  transition: color 0.25s ease, border-color 0.25s ease;
+}
+
+.enter-guest:hover:not(:disabled) {
+  color: #8dffc0;
+  border-color: rgba(124, 255, 178, 0.55);
+}
+
+.enter-guest:focus-visible {
+  outline: 2px solid #b26bff;
+  outline-offset: 3px;
+}
+
+.enter-guest:disabled {
+  opacity: 0.55;
+  cursor: wait;
+}
+
 .enter-smallprint {
   margin: 1.6rem 0 0;
   text-align: center;

frontend/src/pages/EnterPage.tsx

@@ -13,7 +13,7 @@ type EnterMode = 'login' | 'register'
 
 export function EnterPage() {
   const { t } = useTranslation()
-  const { user, login, register } = useAuth()
+  const { user, login, register, guest } = useAuth()
   const navigate = useNavigate()
 
   const [mode, setMode] = useState<EnterMode>('login')
@@ -22,8 +22,10 @@ export function EnterPage() {
   const [error, setError] = useState<string | null>(null)
   const [busy, setBusy] = useState(false)
 
-  // Already seated at the table — no need to knock again.
-  if (user) {
+  // Already seated at the table — no need to knock again. Wanderers are the
+  // exception: the séance's claim-a-name note sends them here to register,
+  // so they must be allowed to stand at the threshold while still seated.
+  if (user && !user.username.startsWith('wanderer-')) {
     return <Navigate to="/seance" replace />
   }
 
@@ -118,6 +120,25 @@ export function EnterPage() {
           </button>
         </form>
 
+        <button
+          type="button"
+          className="enter-guest"
+          disabled={busy}
+          onClick={() => {
+            if (busy) return
+            setError(null)
+            setBusy(true)
+            guest()
+              .then(() => navigate('/seance'))
+              .catch((err) => {
+                setError(err instanceof Error ? err.message : String(err))
+                setBusy(false)
+              })
+          }}
+        >
+          {t('enter.guest')}
+        </button>
+
         <p className="enter-smallprint">
           {t('enter.smallPrint', {
             defaultValue: 'your medium handle is only ever stored on this server',

frontend/src/pages/SeancePage.css

@@ -329,6 +329,50 @@
 
 /* ---------- connection banner ---------- */
 
+.seance-wanderer-note {
+  position: absolute;
+  top: 62px;
+  left: 50%;
+  transform: translateX(-50%);
+  z-index: 29;
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+  padding: 0.4rem 0.9rem;
+  background: rgba(16, 16, 26, 0.92);
+  border: 1px dashed rgba(216, 230, 221, 0.3);
+  border-radius: 3px;
+  color: rgba(216, 230, 221, 0.65);
+  font-size: 0.72rem;
+  letter-spacing: 0.06em;
+  white-space: nowrap;
+}
+
+.seance-wanderer-note a {
+  color: #8dffc0;
+  text-decoration: none;
+  border-bottom: 1px dotted rgba(141, 255, 192, 0.5);
+}
+
+.seance-wanderer-note a:hover {
+  border-bottom-style: solid;
+}
+
+.wanderer-note-dismiss {
+  margin-left: 0.2rem;
+  background: transparent;
+  border: none;
+  color: rgba(216, 230, 221, 0.45);
+  font-size: 0.9rem;
+  line-height: 1;
+  cursor: pointer;
+  padding: 0 0.2rem;
+}
+
+.wanderer-note-dismiss:hover {
+  color: #d8e6dd;
+}
+
 .seance-conn-banner {
   position: absolute;
   top: 62px;

frontend/src/pages/SeancePage.tsx

@@ -108,6 +108,10 @@ function SeanceSession({ username }: { username: string }) {
   const { t, i18n } = useTranslation()
 
   const [departed, setDeparted] = useState(false)
+  // Guests are recognized by their generated name prefix — no backend flag.
+  // Dismissal is per-visit on purpose: the nudge should return next séance.
+  const isWanderer = username.startsWith('wanderer-')
+  const [wandererNoteDismissed, setWandererNoteDismissed] = useState(false)
   const [question, setQuestion] = useState('')
   const [dossierOpen, setDossierOpen] = useState(true)
   const [view, setView] = useState<BoardView>('board')
@@ -306,6 +310,22 @@ function SeanceSession({ username }: { username: string }) {
         </div>
       )}
 
+      {/* ---- wanderer note: guests can claim a permanent name ---- */}
+      {isWanderer && !wandererNoteDismissed && (
+        <div className="seance-wanderer-note" role="note">
+          <span>{t('seance.wanderer.note')}</span>{' '}
+          <Link to="/enter">{t('seance.wanderer.claim')}</Link>
+          <button
+            type="button"
+            className="wanderer-note-dismiss"
+            aria-label={t('seance.wanderer.dismiss')}
+            onClick={() => setWandererNoteDismissed(true)}
+          >
+            ×
+          </button>
+        </div>
+      )}
+
       {/* ---- main: board + side column ---- */}
       <main className="seance-main">
         <section className="seance-board-wrap">

frontend/src/state/auth.tsx

@@ -11,6 +11,7 @@ export type AuthApi = {
   checking: boolean
   login: (username: string, password: string) => Promise<User>
   register: (username: string, password: string) => Promise<User>
+  guest: () => Promise<User>
   logout: () => Promise<void>
 }
 
@@ -42,14 +43,20 @@ export function AuthProvider({ children }: { children: ReactNode }) {
     [login],
   )
 
+  const guest = useCallback(async () => {
+    const u = await api.guest()
+    setUser(u)
+    return u
+  }, [])
+
   const logout = useCallback(async () => {
     await api.logout()
     setUser(null)
   }, [])
 
   const value = useMemo<AuthApi>(
-    () => ({ user, checking, login, register, logout }),
-    [user, checking, login, register, logout],
+    () => ({ user, checking, login, register, guest, logout }),
+    [user, checking, login, register, guest, logout],
   )
   return <AuthContext.Provider value={value}>{children}</AuthContext.Provider>
 }