Initial build: fullhouse, live music bingo from a real Spotify playlist

Based on bingo-bango by f8al (MIT) — same core card-generation idea
("both facets": a square is either an exact song title or an artist,
and an artist square lights up on any of their tracks), reworked with
a real host/guest split, live multiplayer sessions, and cover-art
squares. f8al credited in the footer, README, and PROPOSAL.md.

Three ways to play: host a live session (server-side Spotify
connection, join code + QR, caller screen, auto-call from real
playback), join someone else's session (no login needed), or solo
(guest PKCE login or a pasted public playlist URL, one-off card).

Genuinely verified against a real Spotify account throughout, not
just built and assumed working — including two real bugs found and
fixed along the way (Spotify's playlist-tracks endpoint quietly
renamed to /items with a reshaped response; reading playlist tracks
needs real user auth even for public playlists, so the "no guest
login" public-playlist path routes through the host's connection
instead of a dead-end app-only token). Both Docker images built and
run together on a real network with the nginx proxy verified working
end-to-end, and auto-call confirmed detecting an actual track playing
live through Spotify Connect within one poll tick.

server/routes/hostAuth.js

@@ -0,0 +1,122 @@
+// Host-side Spotify connection — Authorization Code flow, refresh token
+// persisted server-side. Same shape as goonk's api/routes/spotify.mjs
+// (a proven pattern in this family), not the guest PKCE flow used
+// elsewhere in this app — this is a single, long-lived connection to
+// the host's own account, not a per-visitor login.
+import { Router } from 'express';
+import { readFile, writeFile, mkdir } from 'fs/promises';
+import { join, dirname } from 'path';
+import { fileURLToPath } from 'url';
+import crypto from 'crypto';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const router = Router();
+
+const CLIENT_ID = process.env.SPOTIFY_CLIENT_ID;
+const CLIENT_SECRET = process.env.SPOTIFY_CLIENT_SECRET;
+const REDIRECT_URI = process.env.SPOTIFY_HOST_REDIRECT_URI || 'http://127.0.0.1:3010/api/spotify/callback';
+// playlist-read-*: list/read the host's own playlists as a song pool.
+// user-read-currently-playing + user-read-playback-state: the live
+// now-playing auto-call poller.
+const SCOPES = 'playlist-read-private playlist-read-collaborative user-read-currently-playing user-read-playback-state';
+
+const TOKEN_FILE = join(__dirname, '..', 'data', 'host-token.json');
+
+let accessToken = null;
+let accessTokenExpiresAt = 0;
+let refreshToken = null;
+
+async function loadRefreshToken() {
+  if (refreshToken) return refreshToken;
+  try {
+    const raw = await readFile(TOKEN_FILE, 'utf8');
+    refreshToken = JSON.parse(raw).refresh_token;
+  } catch {
+    refreshToken = null;
+  }
+  return refreshToken;
+}
+
+async function saveRefreshToken(token) {
+  refreshToken = token;
+  await mkdir(dirname(TOKEN_FILE), { recursive: true });
+  await writeFile(TOKEN_FILE, JSON.stringify({ refresh_token: token }, null, 2), 'utf8');
+}
+
+async function tokenRequest(params) {
+  const res = await fetch('https://accounts.spotify.com/api/token', {
+    method: 'POST',
+    headers: {
+      'Content-Type': 'application/x-www-form-urlencoded',
+      Authorization: 'Basic ' + Buffer.from(`${CLIENT_ID}:${CLIENT_SECRET}`).toString('base64'),
+    },
+    body: new URLSearchParams(params).toString(),
+  });
+  if (!res.ok) throw new Error(`Spotify token request → ${res.status}: ${await res.text()}`);
+  return res.json();
+}
+
+export async function getHostAccessToken() {
+  if (accessToken && Date.now() < accessTokenExpiresAt) return accessToken;
+
+  const rt = await loadRefreshToken();
+  if (!rt) throw new Error('host not connected — visit /api/spotify/login first');
+
+  const data = await tokenRequest({ grant_type: 'refresh_token', refresh_token: rt });
+  accessToken = data.access_token;
+  accessTokenExpiresAt = Date.now() + (data.expires_in - 60) * 1000;
+  if (data.refresh_token) await saveRefreshToken(data.refresh_token);
+  return accessToken;
+}
+
+export async function isHostConnected() {
+  return Boolean(await loadRefreshToken());
+}
+
+export async function spotifyAsHost(path) {
+  const token = await getHostAccessToken();
+  const res = await fetch(`https://api.spotify.com/v1${path}`, {
+    headers: { Authorization: `Bearer ${token}` },
+  });
+  if (res.status === 204) return null;
+  if (!res.ok) throw new Error(`Spotify ${path} → ${res.status}`);
+  return res.json();
+}
+
+router.get('/login', (req, res) => {
+  const state = crypto.randomBytes(16).toString('hex');
+  res.cookie('fh_host_auth_state', state, { httpOnly: true, maxAge: 5 * 60 * 1000 });
+  const url = new URL('https://accounts.spotify.com/authorize');
+  url.search = new URLSearchParams({
+    response_type: 'code',
+    client_id: CLIENT_ID,
+    scope: SCOPES,
+    redirect_uri: REDIRECT_URI,
+    state,
+  }).toString();
+  res.redirect(url.toString());
+});
+
+router.get('/callback', async (req, res) => {
+  const { code, state, error } = req.query;
+  if (error) return res.status(400).send(`Spotify auth error: ${error}`);
+  if (!state || state !== req.cookies?.fh_host_auth_state) {
+    return res.status(400).send('State mismatch — try /api/spotify/login again');
+  }
+  try {
+    const data = await tokenRequest({ grant_type: 'authorization_code', code, redirect_uri: REDIRECT_URI });
+    await saveRefreshToken(data.refresh_token);
+    accessToken = data.access_token;
+    accessTokenExpiresAt = Date.now() + (data.expires_in - 60) * 1000;
+    res.clearCookie('fh_host_auth_state');
+    res.send('Host Spotify connected — you can close this tab and start a session.');
+  } catch (e) {
+    res.status(502).send(`Token exchange failed: ${e.message}`);
+  }
+});
+
+router.get('/status', async (req, res) => {
+  res.json({ connected: await isHostConnected() });
+});
+
+export default router;

server/routes/hostPlaylists.js

@@ -0,0 +1,88 @@
+import { Router } from 'express';
+import { spotifyAsHost } from './hostAuth.js';
+
+const router = Router();
+
+// Simple in-memory TTL cache — playlists/tracks don't need to be fresher
+// than this, and it keeps a session-start from hammering Spotify's API.
+const CACHE_TTL_MS = 5 * 60 * 1000;
+const cache = new Map();
+function cached(key, fn) {
+  const hit = cache.get(key);
+  if (hit && Date.now() - hit.ts < CACHE_TTL_MS) return Promise.resolve(hit.data);
+  return fn().then(data => { cache.set(key, { data, ts: Date.now() }); return data; });
+}
+
+function summarizePlaylist(p) {
+  return {
+    id: p.id,
+    name: p.name,
+    trackCount: p.items?.total ?? p.tracks?.total ?? 0, // Spotify's field name for this varies by endpoint/version; checked the real response directly
+    image: p.images?.[0]?.url ?? null,
+  };
+}
+
+// Both facets of the card, plus cover art — track title, primary artist,
+// and album art, everything a square could render as.
+function summarizeTrack(entry) {
+  const t = entry.item;
+  if (!t) return null;
+  return {
+    id: t.id,
+    title: t.name,
+    artist: t.artists?.[0]?.name ?? 'Unknown artist',
+    album: t.album?.name ?? '',
+    image: t.album?.images?.[0]?.url ?? null,
+    uri: t.uri,
+  };
+}
+
+// GET /api/host/playlists — the host's own playlists as candidate song pools.
+router.get('/playlists', async (req, res) => {
+  try {
+    const data = await cached('host-playlists', async () => {
+      const out = [];
+      let url = '/me/playlists?limit=50';
+      while (url) {
+        const page = await spotifyAsHost(url);
+        out.push(...(page.items ?? []));
+        url = page.next ? page.next.replace('https://api.spotify.com/v1', '') : null;
+      }
+      return out.map(summarizePlaylist);
+    });
+    res.json(data);
+  } catch (e) {
+    res.status(502).json({ error: e.message });
+  }
+});
+
+// GET /api/host/playlist/:id/tracks — full track pool for one playlist.
+router.get('/playlist/:id/tracks', async (req, res) => {
+  try {
+    const data = await cached(`host-tracks:${req.params.id}`, async () => {
+      const out = [];
+      let url = `/playlists/${req.params.id}/items?limit=100&fields=next,items(item(id,name,uri,artists(name),album(name,images)))`;
+      while (url) {
+        const page = await spotifyAsHost(url);
+        out.push(...(page.items ?? []));
+        url = page.next ? page.next.replace('https://api.spotify.com/v1', '') : null;
+      }
+      return out.map(summarizeTrack).filter(Boolean);
+    });
+    res.json(data);
+  } catch (e) {
+    res.status(502).json({ error: e.message });
+  }
+});
+
+// GET /api/host/now-playing — thin wrapper for the auto-call poller.
+router.get('/now-playing', async (req, res) => {
+  try {
+    const data = await spotifyAsHost('/me/player/currently-playing');
+    res.json(data ?? { playing: false });
+  } catch (e) {
+    res.status(502).json({ error: e.message });
+  }
+});
+
+export default router;

server/routes/publicPlaylist.js

@@ -0,0 +1,83 @@
+// Public-playlist-by-URL lookup — a guest pastes any public Spotify
+// playlist URL and gets a card, with no login of their own required.
+//
+// This originally used a Client Credentials (app-only) token so it
+// wouldn't need anyone's login at all — but Spotify's playlist-items
+// endpoint returns 401 "Valid user authentication required" even for
+// fully public playlists under a pure app token (confirmed directly,
+// not assumed). Routes through the host's already-authenticated
+// connection instead: still genuinely user-authenticated (satisfies
+// Spotify's requirement), and guests still never log into anything —
+// the host's session is what's doing the asking on their behalf.
+import { Router } from 'express';
+import { getHostAccessToken } from './hostAuth.js';
+
+const router = Router();
+
+function extractPlaylistId(input) {
+  const trimmed = input.trim();
+  const urlMatch = trimmed.match(/playlist[/:]([a-zA-Z0-9]+)/);
+  if (urlMatch) return urlMatch[1];
+  if (/^[a-zA-Z0-9]{10,30}$/.test(trimmed)) return trimmed; // bare ID
+  return null;
+}
+
+function summarizeTrack(entry) {
+  const t = entry.item;
+  if (!t) return null;
+  return {
+    id: t.id,
+    title: t.name,
+    artist: t.artists?.[0]?.name ?? 'Unknown artist',
+    album: t.album?.name ?? '',
+    image: t.album?.images?.[0]?.url ?? null,
+    uri: t.uri,
+  };
+}
+
+// GET /api/public-playlist?url=<spotify playlist URL or ID>
+router.get('/', async (req, res) => {
+  const id = extractPlaylistId(String(req.query.url || ''));
+  if (!id) return res.status(400).json({ error: 'could not find a playlist id in that URL' });
+
+  try {
+    const token = await getHostAccessToken();
+    const authed = (path) => fetch(`https://api.spotify.com/v1${path}`, {
+      headers: { Authorization: `Bearer ${token}` },
+    });
+
+    const metaRes = await authed(`/playlists/${id}?fields=name,images,public`);
+    if (!metaRes.ok) {
+      const status = metaRes.status;
+      return res.status(status === 404 ? 404 : 502).json({
+        error: status === 404 ? 'playlist not found' : `Spotify → ${status}`,
+      });
+    }
+    const meta = await metaRes.json();
+    if (meta.public === false) {
+      return res.status(403).json({ error: 'this playlist is private — only the playlist owner can use it as a song pool' });
+    }
+
+    const tracks = [];
+    let url = `/playlists/${id}/items?limit=100&fields=next,items(item(id,name,uri,artists(name),album(name,images)))`;
+    while (url) {
+      const pageRes = await authed(url);
+      if (!pageRes.ok) {
+        return res.status(502).json({ error: `Spotify → ${pageRes.status} while reading tracks (page may be an algorithmic/editorial playlist, which Spotify restricts third-party access to)` });
+      }
+      const page = await pageRes.json();
+      tracks.push(...(page.items ?? []));
+      url = page.next ? page.next.replace('https://api.spotify.com/v1', '') : null;
+    }
+
+    res.json({
+      name: meta.name,
+      image: meta.images?.[0]?.url ?? null,
+      tracks: tracks.map(summarizeTrack).filter(Boolean),
+    });
+  } catch (e) {
+    res.status(502).json({ error: e.message });
+  }
+});
+
+export default router;

server/routes/session.js

@@ -0,0 +1,166 @@
+// Live session state — deliberately in-memory, deliberately polled by
+// clients rather than pushed over a socket. A session is one game night;
+// nothing here needs to survive a restart or scale past one process.
+// Same "boring beats clever" precedent as keep's `watch` command and
+// wisp's TTL sweep elsewhere in this family.
+import { Router } from 'express';
+import crypto from 'crypto';
+import { spotifyAsHost } from './hostAuth.js';
+
+const router = Router();
+
+/** @type {Map<string, Session>} */
+const sessions = new Map();
+
+// code -> interval handle, for the now-playing auto-call poller
+const autoCallTimers = new Map();
+
+function makeCode() {
+  // Short, spoken-aloud-friendly: no 0/O/1/I ambiguity.
+  const alphabet = 'ABCDEFGHJKLMNPQRSTUVWXYZ23456789';
+  let code;
+  do {
+    code = Array.from({ length: 5 }, () => alphabet[crypto.randomInt(alphabet.length)]).join('');
+  } while (sessions.has(code));
+  return code;
+}
+
+function summarizeTrack(entry) {
+  const t = entry.item;
+  if (!t) return null;
+  return {
+    id: t.id,
+    title: t.name,
+    artist: t.artists?.[0]?.name ?? 'Unknown artist',
+    album: t.album?.name ?? '',
+    image: t.album?.images?.[0]?.url ?? null,
+    uri: t.uri,
+  };
+}
+
+async function fetchPlaylistTracks(playlistId) {
+  const out = [];
+  let url = `/playlists/${playlistId}/items?limit=100&fields=next,items(item(id,name,uri,artists(name),album(name,images)))`;
+  while (url) {
+    const page = await spotifyAsHost(url);
+    out.push(...(page.items ?? []));
+    url = page.next ? page.next.replace('https://api.spotify.com/v1', '') : null;
+  }
+  return out.map(summarizeTrack).filter(Boolean);
+}
+
+// POST /api/session — body: { playlistId, playlistName }
+router.post('/', async (req, res) => {
+  const { playlistId, playlistName } = req.body ?? {};
+  if (!playlistId) return res.status(400).json({ error: 'playlistId required' });
+  try {
+    const tracks = await fetchPlaylistTracks(playlistId);
+    if (tracks.length < 12) {
+      return res.status(400).json({ error: `playlist has only ${tracks.length} usable tracks — need at least 12 for a 3x3 card with headroom` });
+    }
+    const code = makeCode();
+    sessions.set(code, {
+      code,
+      playlistName: playlistName || 'Untitled session',
+      tracks,
+      calledIds: [],
+      autoCall: false,
+      createdAt: Date.now(),
+    });
+    res.json({ code, playlistName, trackCount: tracks.length });
+  } catch (e) {
+    res.status(502).json({ error: e.message });
+  }
+});
+
+function requireSession(req, res, next) {
+  const session = sessions.get(String(req.params.code || '').toUpperCase());
+  if (!session) return res.status(404).json({ error: 'session not found — check the code' });
+  req.session = session;
+  next();
+}
+
+// GET /api/session/:code — join payload: full pool (for client-side card
+// generation) + what's been called so far.
+router.get('/:code', requireSession, (req, res) => {
+  const { code, playlistName, tracks, calledIds, autoCall } = req.session;
+  res.json({ code, playlistName, tracks, calledIds, autoCall });
+});
+
+// GET /api/session/:code/state — cheap polling target, no full pool.
+router.get('/:code/state', requireSession, (req, res) => {
+  const { calledIds, autoCall } = req.session;
+  res.json({ calledIds, autoCall });
+});
+
+// POST /api/session/:code/call — body: { trackId } — manual call.
+router.post('/:code/call', requireSession, (req, res) => {
+  const { trackId } = req.body ?? {};
+  const track = req.session.tracks.find(t => t.id === trackId);
+  if (!track) return res.status(400).json({ error: 'trackId not in this session pool' });
+  if (!req.session.calledIds.includes(trackId)) req.session.calledIds.push(trackId);
+  res.json({ calledIds: req.session.calledIds });
+});
+
+// POST /api/session/:code/call-random — classic caller draw, no replacement.
+router.post('/:code/call-random', requireSession, (req, res) => {
+  const remaining = req.session.tracks.filter(t => !req.session.calledIds.includes(t.id));
+  if (!remaining.length) return res.status(409).json({ error: 'every track has already been called' });
+  const pick = remaining[crypto.randomInt(remaining.length)];
+  req.session.calledIds.push(pick.id);
+  res.json({ called: pick, calledIds: req.session.calledIds });
+});
+
+// POST /api/session/:code/autocall/start — polls the host's actual
+// Spotify playback and auto-calls whatever's currently playing, if it's
+// in this session's pool. Manual /call and /call-random keep working
+// alongside it — this is a bonus layer, not a replacement.
+router.post('/:code/autocall/start', requireSession, (req, res) => {
+  const { code } = req.session;
+  if (autoCallTimers.has(code)) return res.json({ ok: true, already: true });
+
+  let lastSeenTrackId = null;
+  const timer = setInterval(async () => {
+    const session = sessions.get(code);
+    if (!session) { clearInterval(timer); autoCallTimers.delete(code); return; }
+    try {
+      const playing = await spotifyAsHost('/me/player/currently-playing');
+      const trackId = playing?.item?.id;
+      if (!trackId || trackId === lastSeenTrackId) return;
+      lastSeenTrackId = trackId;
+      if (session.tracks.some(t => t.id === trackId) && !session.calledIds.includes(trackId)) {
+        session.calledIds.push(trackId);
+      }
+    } catch {
+      // host playback unavailable this tick — try again next tick, not fatal
+    }
+  }, 5000);
+
+  autoCallTimers.set(code, timer);
+  req.session.autoCall = true;
+  res.json({ ok: true });
+});
+
+router.post('/:code/autocall/stop', requireSession, (req, res) => {
+  const { code } = req.session;
+  const timer = autoCallTimers.get(code);
+  if (timer) { clearInterval(timer); autoCallTimers.delete(code); }
+  req.session.autoCall = false;
+  res.json({ ok: true });
+});
+
+// Sessions are ephemeral by design — sweep anything older than 12h so a
+// forgotten session doesn't sit in memory forever. Deliberately dumb
+// interval, same precedent as the rest of this family.
+setInterval(() => {
+  const cutoff = Date.now() - 12 * 60 * 60 * 1000;
+  for (const [code, session] of sessions) {
+    if (session.createdAt < cutoff) {
+      const timer = autoCallTimers.get(code);
+      if (timer) { clearInterval(timer); autoCallTimers.delete(code); }
+      sessions.delete(code);
+    }
+  }
+}, 60 * 60 * 1000);
+
+export default router;