One sign-in module (openvibe-sdk/sso): /auth/health for the canary (#38)

ddiff --git a/server/auth/sso.js b/server/auth/sso.js
iindex a3b9d77..9bc9a71 100644
---- a/server/auth/sso.js
++++ b/server/auth/sso.js
@@@ -1,26 +1,33 @@
  'use strict';
  
  /**
-- * Sign-in with OpenVibe.Network: OAuth 2 authorization code with PKCE (S256), as OAuth client `shoes`.
++ * Sign-in with OpenVibe.Network: openvibe-sdk/sso (0.73.0) is the one module every site uses. This file is this
++ * site's thin wrapper around it — the routes, the middleware and the shapes this site's pages still read.
   *
-- *   GET  /auth/login      → Network /oauth/authorize?…&code_challenge=…&code_challenge_method=S256
-- *                           (?silent=1 adds prompt=none; ?next= a same-site path)
-- *   GET  /auth/callback   → state check, server-side code exchange (client secret + code_verifier)
-- *   GET  /auth/logout     → clear cookies, revoke the refresh token (best effort)
-- *   GET  /auth/me         → { user } for the shared navbar; { user: null } for a guest
++ *   GET  /auth/login     → Network /oauth/authorize with state and PKCE (S256); ?next, ?silent, ?prompt, ?login_hint
++ *   GET  /auth/callback  → the state is compared in constant time, the code is exchanged server-side (client secret)
++ *   GET  /auth/logout    → the cookies are cleared, the refresh token revoked (best effort)
++ *   GET  /auth/me        → { user } for the shared navbar
++ *   GET  /auth/health    → { ok, client }: does the Network accept this site's OAuth client?
++ *   POST /auth/fedcm     → the shared navbar's FedCM assertion, swapped for tokens
++ *   POST /auth/refresh   → the tokens are rotated with the refresh token
   *
-- * This is Today's SSO module with the client id and cookie names changed. The person's Network access token lives
-- * in an httpOnly cookie (shoes_at) no script can read; the refresh token (shoes_rt) is httpOnly too. Neither is ever
-- * stored server-side, rendered or logged.
++ * The SDK recovers by itself once (a lost or expired flow, a code the Network no longer accepts) and shows a page
++ * with "Try again" when it cannot: no more a bare "The Network refused the sign-in code." A client the Network
++ * refuses is logged as a configuration error, and GET /auth/health answers 503 for it.
++ *
++ * The person's old cookie (shoes_at) is read as the session until the next sign-in or refresh writes ov_token, so
++ * nobody is signed out by the move. The access token stays httpOnly: no script can read it (the navbar asks
++ * /auth/me). The same token is what this site forwards to the other OpenVibe services.
   */
  const crypto = require('crypto');
  const express = require('express');
  const cache = require('openvibe-shared/cache-policy');
++const { createSsoClient, COOKIES, parseCookies, sanitizeNext } = require('openvibe-sdk/sso');
  
  const ACCESS_COOKIE = 'shoes_at';
  const REFRESH_COOKIE = 'shoes_rt';
  const HINT_COOKIE = 'ov_sso_hint';
--const FLOW_COOKIE = 'shoes_oauth';
  
  function pkcePair() {
      const verifier = crypto.randomBytes(32).toString('base64url');
@@@ -36,19 +43,7 @@ function ownOrigins(config) {
      return out;
  }
  
--/** Same-site relative paths only (never protocol-relative, never another origin). */
--function sanitizeNext(next, config) {
--    if (typeof next === 'string' && /[\u0000-\u001f\u007f\\]/.test(next)) return '/';
--    if (typeof next === 'string' && /^https?:\/\//i.test(next)) {
--        let u = null;
--        try { u = new URL(next); } catch { return '/'; }
--        if (!ownOrigins(config).has(u.origin)) return '/';
--        next = `${u.pathname}${u.search}${u.hash}`;
--    }
--    if (typeof next !== 'string' || !/^\/(?!\/|\\)/.test(next) || next.length > 500) return '/';
--    return next;
--}
--
++/** The authorize URL for a sign-in (pure; the SDK builds its own, this one stays for the site's tests). */
  function authorizeUrl(config, { state, challenge, silent = false }) {
      const q = new URLSearchParams({
          response_type: 'code',
@@@ -64,57 +59,39 @@ function authorizeUrl(config, { state, challenge, silent = false }) {
  }
  
  function createSso({ config, keys, fetchImpl = globalThis.fetch, now = () => Date.now(), log = console }) {
--    const cookieBase = () => ({ sameSite: 'lax', secure: config.cookies.secure, httpOnly: true, path: '/' });
--
--    function setSession(res, data) {
--        res.cookie(ACCESS_COOKIE, data.access_token, { ...cookieBase(), maxAge: 24 * 60 * 60 * 1000 });
--        if (data.refresh_token) res.cookie(REFRESH_COOKIE, data.refresh_token, { ...cookieBase(), maxAge: 30 * 24 * 60 * 60 * 1000 });
--        res.cookie(HINT_COOKIE, 'account', { sameSite: 'lax', secure: config.cookies.secure, httpOnly: false, path: '/', maxAge: 365 * 24 * 60 * 60 * 1000 });
--    }
--    function clearSession(res) {
--        res.clearCookie(ACCESS_COOKIE, cookieBase());
--        res.clearCookie(REFRESH_COOKIE, cookieBase());
--    }
--
--    async function tokenGrant(fields) {
--        const body = new URLSearchParams({ client_id: config.oauth.clientId, client_secret: config.oauth.clientSecret, ...fields });
--        let res;
--        try {
--            res = await fetchImpl(`${config.networkInternalUrl}/oauth/token`, {
--                method: 'POST',
--                headers: { 'Content-Type': 'application/x-www-form-urlencoded', Accept: 'application/json' },
--                body, signal: AbortSignal.timeout(10_000),
--            });
--        } catch (err) {
--            throw Object.assign(new Error('OpenVibe.Network did not answer'), { status: 502, error: err && err.name === 'TimeoutError' ? 'timeout' : 'unreachable' });
--        }
--        const data = await res.json().catch(() => null);
--        if (!res.ok || !data || !data.access_token) {
--            throw Object.assign(new Error((data && (data.error_description || data.error)) || `token endpoint ${res.status}`),
--                { status: res.status, error: (data && data.error) || 'invalid_grant' });
--        }
--        return data;
--    }
++    // The one module. The site's own values, its own old cookies, and the audience it always verified with.
++    const sso = createSsoClient({
++        site: 'shoes',
++        siteName: 'OpenVibe.Shoes',
++        baseUrl: config.baseUrl,
++        clientId: config.oauth.clientId,
++        clientSecret: config.oauth.clientSecret,
++        networkUrl: config.networkPublicUrl || config.networkUrl,
++        networkInternalUrl: config.networkInternalUrl || config.networkUrl,
++        issuer: config.networkIssuer || config.networkPublicUrl || config.networkUrl,
++        redirectUri: config.oauth.redirectUri,
++        scope: config.oauth.scope,
++        audience: config.oauth.sessionAudience,
++        secureCookies: config.cookies.secure !== false,
++        httpOnlyAccess: true,
++        legacyCookies: { access: [ACCESS_COOKIE], refresh: [REFRESH_COOKIE] },
++        fetch: fetchImpl,
++        log,
++    });
  
--    /**
--     * A Shoes session is a Network SESSION token: audience openvibe.network and a person. FedCM assertions,
--     * app/service tokens and internal tokens are signed with the same key and issuer; none may become a session here.
--     */
--    async function verifySession(token) {
--        const v = await keys.verifyUser(token, { issuer: config.networkIssuer, audience: config.oauth.sessionAudience, now: now() });
--        const c = v.claims;
--        if (c && (c.typ === 'fedcm' || c.actor_type !== undefined)) return { ok: false, reason: 'not a session token' };
--        return v;
--    }
++    const cookieBase = () => ({ sameSite: 'lax', secure: config.cookies.secure !== false, httpOnly: true, path: '/' });
++    const nextOf = (value) => sanitizeNext(value, { baseUrl: config.baseUrl, networkUrl: config.networkUrl });
  
--    function viewerFromClaims(claims, token) {
++    /** The person, in the shape this site's pages read (req.viewer). */
++    function viewerFrom(claims, token) {
          const subject = typeof claims.subject_id === 'string' ? claims.subject_id : null;
          const role = typeof claims.role === 'string' ? claims.role : 'user';
++        const username = typeof claims.username === 'string' ? claims.username.slice(0, 64) : null;
          return {
              kind: 'user',
              subject,
--            username: typeof claims.username === 'string' ? claims.username.slice(0, 64) : null,
--            displayName: typeof claims.display_name === 'string' ? claims.display_name.slice(0, 80) : (typeof claims.username === 'string' ? claims.username.slice(0, 64) : 'you'),
++            username,
++            displayName: typeof claims.display_name === 'string' ? claims.display_name.slice(0, 80) : (username || 'you'),
              role,
              avatarUrl: typeof claims.avatar_url === 'string' && /^https:\/\/[^\s"'<>]{1,500}$/.test(claims.avatar_url) ? claims.avatar_url : null,
              profileColor: typeof claims.profile_color === 'string' && /^#[0-9a-fA-F]{3,8}$/.test(claims.profile_color) ? claims.profile_color : null,
@@@ -122,96 +99,91 @@ function createSso({ config, keys, fetchImpl = globalThis.fetch, now = () => Dat
          };
      }
  
--    async function refresh(req, res) {
--        if (!req.sessionRefresh) req.sessionRefresh = await doRefresh(req, res);
--        return req.sessionRefresh;
--    }
++    /** The public profile the navbar and the API read. */
++    const meOf = (claims) => ({
++        username: typeof claims.username === 'string' ? claims.username.slice(0, 64) : null,
++        display_name: typeof claims.display_name === 'string' ? claims.display_name.slice(0, 80) : null,
++        subject_id: typeof claims.subject_id === 'string' ? claims.subject_id : null,
++        role: typeof claims.role === 'string' ? claims.role : 'user',
++        avatar_url: typeof claims.avatar_url === 'string' ? claims.avatar_url.slice(0, 500) : null,
++        profile_color: typeof claims.profile_color === 'string' ? claims.profile_color.slice(0, 16) : null,
++    });
  
--    async function doRefresh(req, res) {
--        const rt = req.cookies && req.cookies[REFRESH_COOKIE];
++    /**
++     * The access token expired (or is gone) but the refresh token is still there: rotate it and write the SDK's own
++     * cookies, the same names and options the SDK uses. The old cookies are cleared.
++     */
++    async function refreshSession(req, res) {
++        const c = parseCookies(req);
++        const rt = c[COOKIES.refresh] || c[REFRESH_COOKIE];
          if (!rt) return null;
--        try {
--            const data = await tokenGrant({ grant_type: 'refresh_token', refresh_token: rt });
--            setSession(res, data);
--            const v = await verifySession(data.access_token);
--            return v.ok ? viewerFromClaims(v.claims, data.access_token) : null;
--        } catch (err) {
--            if (err.status && err.status < 500) clearSession(res);
--            return null;
--        }
++        let data = null;
++        try { data = await sso.tokenGrant({ grant_type: 'refresh_token', refresh_token: rt }); } catch { return null; }
++        if (!data || !data.access_token) return null;
++        const claims = await sso.verify(data.access_token);
++        if (!claims) return null;
++        res.cookie(COOKIES.access, data.access_token, { ...cookieBase(), maxAge: 24 * 60 * 60 * 1000 });
++        if (data.refresh_token) res.cookie(COOKIES.refresh, data.refresh_token, { ...cookieBase(), path: '/auth', maxAge: 30 * 24 * 60 * 60 * 1000 });
++        res.clearCookie(ACCESS_COOKIE, { path: '/' });
++        res.clearCookie(REFRESH_COOKIE, { path: '/' });
++        return { claims, token: data.access_token };
      }
  
--    /** req.viewer for every page: the signed-in person, refreshed when their token expired. */
++    /** req.user and req.token for a valid session; req.viewer keeps this site's pages working as they are. */
      function middleware() {
--        return async (req, res, next) => {
++        const optional = sso.optionalAuth();
++        return (req, res, next) => {
              req.viewer = { kind: 'anonymous' };
--            const token = req.cookies && req.cookies[ACCESS_COOKIE];
--            if (!token) return next();
--            await keys.ensure();
--            const v = await verifySession(token);
--            if (v.ok) { req.viewer = viewerFromClaims(v.claims, token); return next(); }
--            if (v.expired) {
--                const fresh = await refresh(req, res);
--                if (fresh) { req.viewer = fresh; return next(); }
--            }
--            if (keys.loaded()) clearSession(res);
--            next();
++            optional(req, res, async () => {
++                try {
++                    if (req.user && req.token) { req.viewer = viewerFrom(req.user, req.token); return next(); }
++                    const fresh = await refreshSession(req, res);
++                    if (fresh) {
++                        req.user = fresh.claims;
++                        req.token = fresh.token;
++                        req.viewer = viewerFrom(fresh.claims, fresh.token);
++                    }
++                } catch (err) {
++                    log.warn('[OpenVibe.Shoes] session refresh failed:', (err && err.message) || err);
++                }
++                return next();
++            });
          };
      }
  
++    /** A call with the person's own token; a 401 refreshes the session once and tries again. */
      async function asViewer(req, res, fn) {
++        const token = req.token || (req.viewer && req.viewer.token) || null;
++        if (!token) throw Object.assign(new Error('Not signed in'), { status: 401 });
          try {
--            return await fn(req.viewer.token);
++            return await fn(token);
          } catch (err) {
              if (!err || err.status !== 401) throw err;
--            const fresh = await refresh(req, res);
++            const fresh = await refreshSession(req, res);
              if (!fresh) throw err;
--            req.viewer = fresh;
++            req.user = fresh.claims;
++            req.token = fresh.token;
++            req.viewer = viewerFrom(fresh.claims, fresh.token);
              return fn(fresh.token);
          }
      }
  
      function routes() {
          const r = express.Router();
--        const flowOpts = () => ({ ...cookieBase(), path: '/auth', maxAge: 10 * 60 * 1000 });
  
--        r.get('/login', (req, res) => {
--            const silent = Boolean(req.query.silent) && req.query.silent !== '0';
--            const state = crypto.randomBytes(16).toString('hex');
--            const { verifier, challenge } = pkcePair();
--            res.cookie(FLOW_COOKIE, JSON.stringify({ state, verifier, next: sanitizeNext(req.query.next, config), silent }), flowOpts());
++        // GET /auth/me: the shared navbar's answer. A guest is { user: null } (200); a session that does not verify
++        // is 401, as it always was here.
++        r.get('/me', async (req, res) => {
              res.set('Cache-Control', cache.htmlHeaders({ private: true }));
--            res.redirect(authorizeUrl(config, { state, challenge, silent }));
--        });
--
--        r.get('/callback', async (req, res) => {
--            res.set('Cache-Control', cache.htmlHeaders({ private: true }));
--            let flow = null;
--            try { flow = JSON.parse(req.cookies[FLOW_COOKIE] || 'null'); } catch { flow = null; }
--            res.clearCookie(FLOW_COOKIE, { ...cookieBase(), path: '/auth' });
--            const next = flow ? sanitizeNext(flow.next, config) : '/';
--            const { code, state, error } = req.query;
--            if (error) {
--                if ((flow && flow.silent) || error === 'login_required' || error === 'interaction_required') return res.redirect(next);
--                return res.status(400).type('text/plain').send(`Sign-in was not completed (${String(error).slice(0, 60)}).`);
--            }
--            if (!flow || typeof flow.state !== 'string' || typeof flow.verifier !== 'string' || typeof state !== 'string'
--                || state.length !== flow.state.length || !crypto.timingSafeEqual(Buffer.from(state), Buffer.from(flow.state))) {
--                return res.status(400).type('text/plain').send('Sign-in state did not match. Please try signing in again.');
--            }
--            if (!code) return res.status(400).type('text/plain').send('The Network sent no authorization code.');
--            try {
--                const data = await tokenGrant({ grant_type: 'authorization_code', code: String(code), redirect_uri: config.oauth.redirectUri, code_verifier: flow.verifier });
--                setSession(res, data);
--                res.set('Clear-Site-Data', '"cache"');
--                return res.redirect(next);
--            } catch (err) {
--                log.warn('[OpenVibe.Shoes] sign-in exchange failed:', err.status || '', err.error || '');
--                return res.status(err.status && err.status < 500 ? 400 : 502).type('text/plain')
--                    .send(err.status && err.status < 500 ? 'The Network refused the sign-in code. Please sign in again.' : 'Sign-in failed: OpenVibe.Network did not answer. Please try again.');
--            }
++            const c = parseCookies(req);
++            const presented = Boolean(c[COOKIES.access] || c[ACCESS_COOKIE] || c[COOKIES.refresh] || c[REFRESH_COOKIE] || req.get('authorization'));
++            if (!presented) return res.json({ user: null });
++            const claims = await sso.verify(sso.extractToken(req));
++            if (!claims) return res.status(401).json({ error: 'Not signed in' });
++            return res.json({ user: meOf(claims) });
          });
  
++        // Sign-out stays a same-site action: another site cannot sign a person out.
          const sameOriginRequest = (req) => {
              const site = String(req.get('sec-fetch-site') || '');
              if (site) return site === 'same-origin' || (site === 'none' && req.method === 'GET');
@@@ -222,14 +194,17 @@ function createSso({ config, keys, fetchImpl = globalThis.fetch, now = () => Dat
          r.get('/logout', (req, res, next) => {
              if (sameOriginRequest(req)) return next();
              res.set('Cache-Control', cache.htmlHeaders({ private: true }));
--            const q = req.query.next ? `?next=${encodeURIComponent(sanitizeNext(req.query.next, config))}` : '';
--            res.type('html').send(`<!doctype html><meta charset="utf-8"><title>Sign out</title><meta name="viewport" content="width=device-width,initial-scale=1">`
++            const q = req.query.next ? `?next=${encodeURIComponent(nextOf(req.query.next))}` : '';
++            res.type('html').send('<!doctype html><meta charset="utf-8"><title>Sign out</title><meta name="viewport" content="width=device-width,initial-scale=1">'
                  + `<form method="post" action="/auth/logout${q}" style="font:16px system-ui;margin:3em auto;max-width:24em;text-align:center">`
--                + `<p>Sign out of OpenVibe.Shoes?</p><button type="submit">Sign out</button> <a href="/">Cancel</a></form>`);
++                + '<p>Sign out of OpenVibe.Shoes?</p><button type="submit">Sign out</button> <a href="/">Cancel</a></form>');
          });
          r.post('/logout', (req, res, next) => (sameOriginRequest(req) ? next() : res.status(403).type('text/plain').send('Sign-out must come from this site.')));
          r.all('/logout', async (req, res) => {
--            const rt = req.cookies && req.cookies[REFRESH_COOKIE];
++            // Any other verb (a DELETE from another site) is refused like the POST is.
++            if (!sameOriginRequest(req)) return res.status(403).type('text/plain').send('Sign-out must come from this site.');
++            const c = parseCookies(req);
++            const rt = c[COOKIES.refresh] || c[REFRESH_COOKIE];
              if (rt) {
                  fetchImpl(`${config.networkInternalUrl}/oauth/revoke`, {
                      method: 'POST', headers: { 'Content-Type': 'application/json' },
@@@ -237,24 +212,21 @@ function createSso({ config, keys, fetchImpl = globalThis.fetch, now = () => Dat
                      signal: AbortSignal.timeout(3000),
                  }).catch(() => {});
              }
--            clearSession(res);
++            res.clearCookie(COOKIES.access, { path: '/' });
++            res.clearCookie(COOKIES.refresh, { path: '/auth' });
++            res.clearCookie(ACCESS_COOKIE, { path: '/' });
++            res.clearCookie(REFRESH_COOKIE, { path: '/' });
              res.set('Clear-Site-Data', '"cache"');
--            res.cookie(HINT_COOKIE, 'guest', { sameSite: 'lax', secure: config.cookies.secure, httpOnly: false, path: '/', maxAge: 365 * 24 * 60 * 60 * 1000 });
--            res.redirect(303, sanitizeNext(req.query.next, config));
++            res.cookie(HINT_COOKIE, 'guest', { sameSite: 'lax', secure: config.cookies.secure !== false, httpOnly: false, path: '/', maxAge: 365 * 24 * 60 * 60 * 1000 });
++            return res.redirect(303, nextOf(req.query.next));
          });
  
--        r.get('/me', (req, res) => {
--            res.set('Cache-Control', cache.htmlHeaders({ private: true }));
--            const c = req.cookies || {};
--            if (!c[ACCESS_COOKIE] && !c[REFRESH_COOKIE] && !req.get('authorization')) return res.json({ user: null });
--            const v = req.viewer;
--            if (!v || v.kind !== 'user') return res.status(401).json({ error: 'Not signed in' });
--            res.json({ user: { username: v.username, display_name: v.displayName, subject_id: v.subject, role: v.role, avatar_url: v.avatarUrl || null, profile_color: v.profileColor || null } });
--        });
++        // The SDK's own routes: /login, /callback, /fedcm, /refresh, /health.
++        r.use(sso.router(express));
          return r;
      }
  
--    return { middleware, routes, asViewer, tokenGrant, pkcePair };
++    return { middleware, routes, asViewer, tokenGrant: (fields) => sso.tokenGrant(fields), pkcePair, client: sso, checkClient: (o) => sso.checkClient(o) };
  }
  
  module.exports = { createSso, pkcePair, sanitizeNext, ownOrigins, authorizeUrl, ACCESS_COOKIE, REFRESH_COOKIE };
ddiff --git a/test/sso.test.js b/test/sso.test.js
iindex d95ec54..edf6952 100644
---- a/test/sso.test.js
++++ b/test/sso.test.js
@@@ -1,13 +1,15 @@
  'use strict';
  /**
-- * Sign-in with PKCE S256 (client id shoes, cookies shoes_at/shoes_rt/shoes_oauth), the session-token rules (a
-- * FedCM assertion or an app token is not a session), the open-redirect guard, truthful readiness, loopback
-- * metrics, pages without JavaScript, and cross-site sign-out.
++ * Sign-in through openvibe-sdk/sso (PKCE S256, client id shoes; the SDK's cookies ov_token/ov_refresh/ov_oauth_state,
++ * and the old shoes_at still read as the session), the session-token rules (a FedCM assertion or an app token is not a
++ * session), the open-redirect guard, /auth/health, truthful readiness, loopback metrics, pages without JavaScript, and
++ * cross-site sign-out.
   */
  const assert = require('assert');
  const crypto = require('crypto');
  const { boot, check, done } = require('./helpers/boot');
  const { sanitizeNext } = require('../server/auth/sso');
++const cookieJar = (res) => res.headers.getSetCookie().map((c) => c.split(';')[0]).join('; ');
  
  (async () => {
      const t = await boot();
@@@ -21,50 +23,65 @@ const { sanitizeNext } = require('../server/auth/sso');
          assert.strictEqual(loc.searchParams.get('client_id'), 'shoes');
          assert.strictEqual(loc.searchParams.get('code_challenge_method'), 'S256');
          assert.match(loc.searchParams.get('code_challenge'), /^[A-Za-z0-9_-]{43}$/);
--        assert.match(loc.searchParams.get('state'), /^[0-9a-f]{32}$/);
--        assert.match(r.headers.get('set-cookie'), /shoes_oauth=.*Path=\/auth.*HttpOnly/i);
++        assert.match(loc.searchParams.get('state'), /^[A-Za-z0-9_-]{32}$/);
++        assert.match(r.headers.get('set-cookie'), /ov_oauth_state=.*Path=\/auth.*HttpOnly/i);
      });
  
      await check('callback exchanges the code with the matching verifier and sets httpOnly session cookies', async () => {
          const login = await t.get('/auth/login?next=/shoe/nike-air-max-90');
          const loc = new URL(login.headers.get('location'));
--        const flowCookie = login.headers.get('set-cookie').split(';')[0];
++        const flowCookie = cookieJar(login);
          const code = t.network.issueCode(user, loc.searchParams.get('code_challenge'));
          const r = await t.get(`/auth/callback?code=${code}&state=${loc.searchParams.get('state')}`, { cookie: flowCookie });
          assert.strictEqual(r.status, 302, r.text);
          assert.strictEqual(r.headers.get('location'), '/shoe/nike-air-max-90');
          const set = r.headers.get('set-cookie');
--        assert.match(set, /shoes_at=[^;]+;.*HttpOnly/i);
--        assert.match(set, /shoes_rt=[^;]+;.*HttpOnly/i);
--        assert.match(set, /shoes_oauth=;/);
--        const at = set.match(/shoes_at=([^;]+)/)[1];
--        const me = await t.get('/auth/me', { cookie: `shoes_at=${at}` });
++        assert.match(set, /ov_token=[^;]+;.*HttpOnly/i);
++        assert.match(set, /ov_refresh=[^;]+;.*HttpOnly/i);
++        assert.match(set, /ov_oauth_state=;/);
++        const at = set.match(/ov_token=([^;]+)/)[1];
++        const me = await t.get('/auth/me', { cookie: `ov_token=${at}` });
          assert.strictEqual(me.json().user.username, 'kim');
          assert.ok(!me.text.includes(at), '/auth/me never returns the token');
      });
  
--    await check('a wrong state, a verifier that does not match, or no flow cookie is refused', async () => {
++    await check('a wrong state, a verifier that does not match, or no flow cookie starts the sign-in once more', async () => {
          const login = await t.get('/auth/login');
          const loc = new URL(login.headers.get('location'));
--        const flowCookie = login.headers.get('set-cookie').split(';')[0];
++        const flowCookie = cookieJar(login);
          const code = t.network.issueCode(user, loc.searchParams.get('code_challenge'));
          const bad = await t.get(`/auth/callback?code=${code}&state=${'0'.repeat(32)}`, { cookie: flowCookie });
--        assert.strictEqual(bad.status, 400);
++        assert.strictEqual(bad.status, 302, 'the SDK recovers by itself once');
++        assert.match(bad.headers.get('location'), /^\/auth\/login/);
++        const retry = cookieJar(bad);
++        assert.match(retry, /ov_oauth_retry=1/);
++        const again = await t.get(`/auth/callback?code=${code}&state=${'0'.repeat(32)}`, { cookie: `${flowCookie}; ${retry}` });
++        assert.strictEqual(again.status, 400);
++        assert.match(again.text, /Try again/);
          const other = t.network.issueCode(user, crypto.createHash('sha256').update('another-verifier').digest('base64url'));
--        const mismatch = await t.get(`/auth/callback?code=${other}&state=${loc.searchParams.get('state')}`, { cookie: flowCookie });
--        assert.strictEqual(mismatch.status, 400);
--        const noCookie = await t.get(`/auth/callback?code=${code}&state=${loc.searchParams.get('state')}`);
--        assert.strictEqual(noCookie.status, 400);
++        assert.strictEqual((await t.get(`/auth/callback?code=${other}&state=${loc.searchParams.get('state')}`, { cookie: flowCookie })).status, 302);
++        assert.strictEqual((await t.get(`/auth/callback?code=${code}&state=${loc.searchParams.get('state')}`)).status, 302);
      });
  
      await check('next= only accepts same-site paths', async () => {
          const r = await t.get('/auth/login?next=//evil.example/x');
--        const flow = decodeURIComponent(r.headers.get('set-cookie').match(/shoes_oauth=([^;]+)/)[1]);
--        assert.strictEqual(JSON.parse(flow).next, '/');
--        const config = { baseUrl: 'https://open.shoes' };
--        assert.strictEqual(sanitizeNext('/shoe/nike-air-max-90?x=1', config), '/shoe/nike-air-max-90?x=1');
--        assert.strictEqual(sanitizeNext('https://open.shoes/drops?y=1', config), '/drops?y=1');
--        for (const v of ['//evil.com', '/\\evil.com', 'https://evil.com/x', '/\t/evil.com', 'javascript:alert(1)', 'https://open.shoes.evil.com/x']) assert.strictEqual(sanitizeNext(v, config), '/', v);
++        assert.ok(/ov_oauth_next=;/.test(String(r.headers.get('set-cookie') || '')), 'a cross-site next is dropped');
++        const opts = { baseUrl: 'https://open.shoes', networkUrl: 'https://openvibe.network' };
++        assert.strictEqual(sanitizeNext('/shoe/nike-air-max-90?x=1', opts), '/shoe/nike-air-max-90?x=1');
++        assert.strictEqual(sanitizeNext('https://open.shoes/drops?y=1', opts), 'https://open.shoes/drops?y=1');
++        for (const v of ['//evil.com', '/\\evil.com', 'https://evil.com/x', '/\t/evil.com', 'javascript:alert(1)', 'https://open.shoes.evil.com/x']) assert.strictEqual(sanitizeNext(v, opts), '/', v);
++    });
++
++    await check('/auth/health says whether the Network accepts this client (the sign-in canary)', async () => {
++        const r = await t.get('/auth/health');
++        assert.strictEqual(r.status, 200);
++        assert.deepStrictEqual(r.json(), { ok: true, client: 'ok' });
++    });
++
++    await check('the old cookie is still the session, so nobody is signed out by the move', async () => {
++        const me = await t.get('/auth/me', { cookie: `shoes_at=${t.network.userToken(user)}` });
++        assert.strictEqual(me.status, 200);
++        assert.strictEqual(me.json().user.username, 'kim');
      });
  
      await check('readiness is truthful: db required; JWKS, the OAuth client and Valkey optional', async () => {