refactor: improve pollSessions error handling and test coverage

muxplex/frontend/app.js

@@ -173,7 +173,9 @@ async function api(method, path, body, baseUrl) {
   }
   const res = await fetch(url, opts);
   if (!res.ok) {
-    throw new Error(`HTTP ${res.status}: ${res.statusText}`);
+    const err = new Error(`HTTP ${res.status}: ${res.statusText}`);
+    err.status = res.status;
+    throw err;
   }
   return res;
 }
@@ -248,7 +250,7 @@ function setConnectionStatus(level) {
  */
 async function pollSessions() {
   // Falls back to local-only if _sources is empty
-  if (!_sources || _sources.length === 0) {
+  if (_sources.length === 0) {
     try {
       const res = await api('GET', '/api/sessions');
       const sessions = await res.json();
@@ -284,8 +286,7 @@ async function pollSessions() {
         delete source.nextRetryAt;
         return { source, sessions };
       } catch (err) {
-        const msg = err.message || '';
-        if (msg.includes('401') || msg.includes('403')) {
+        if (err.status === 401 || err.status === 403) {
           source.status = 'auth_required';
         } else {
           source.status = 'unreachable';

muxplex/frontend/tests/test_app.mjs

@@ -2190,4 +2190,149 @@ test('pollSessions fetches from all sources and merges results', async () => {
   app._setSources([]);
 });
 
+test('pollSessions skips sources with nextRetryAt in the future', async () => {
+  const mockStatusEl = { textContent: '', className: '' };
+  const mockGrid = { innerHTML: '' };
+  const mockEmptyState = { style: {}, classList: { add: () => {}, remove: () => {} } };
+
+  const origGetById = globalThis.document.getElementById;
+  const origQSA = globalThis.document.querySelectorAll;
+  globalThis.document.getElementById = (id) => {
+    if (id === 'connection-status') return mockStatusEl;
+    if (id === 'session-grid') return mockGrid;
+    if (id === 'empty-state') return mockEmptyState;
+    return null;
+  };
+  globalThis.document.querySelectorAll = () => [];
+
+  const futureRetry = Date.now() + 60000; // 60s in the future
+  app._setSources([
+    { url: '', name: 'Local', type: 'local', status: 'authenticated', backoffMs: 2000 },
+    {
+      url: 'https://remote.example.com',
+      name: 'Remote',
+      type: 'remote',
+      status: 'unreachable',
+      backoffMs: 4000,
+      nextRetryAt: futureRetry,
+    },
+  ]);
+
+  const fetchCalls = [];
+  globalThis.fetch = async (url) => {
+    fetchCalls.push(url);
+    return { ok: true, json: async () => [{ name: 'local-session' }] };
+  };
+
+  await app.pollSessions();
+
+  assert.ok(fetchCalls.some((url) => url === '/api/sessions'), 'should fetch local sessions');
+  assert.ok(
+    !fetchCalls.some((url) => url === 'https://remote.example.com/api/sessions'),
+    'should skip remote source still in backoff',
+  );
+
+  globalThis.document.getElementById = origGetById;
+  globalThis.document.querySelectorAll = origQSA;
+  globalThis.fetch = undefined;
+  app._setSources([]);
+});
+
+test('pollSessions sets auth_required on 401 response', async () => {
+  const mockStatusEl = { textContent: '', className: '' };
+  const mockGrid = { innerHTML: '' };
+  const mockEmptyState = { style: {}, classList: { add: () => {}, remove: () => {} } };
+
+  const origGetById = globalThis.document.getElementById;
+  const origQSA = globalThis.document.querySelectorAll;
+  globalThis.document.getElementById = (id) => {
+    if (id === 'connection-status') return mockStatusEl;
+    if (id === 'session-grid') return mockGrid;
+    if (id === 'empty-state') return mockEmptyState;
+    return null;
+  };
+  globalThis.document.querySelectorAll = () => [];
+
+  const sources = [
+    { url: '', name: 'Local', type: 'local', status: 'authenticated', backoffMs: 2000 },
+    {
+      url: 'https://remote.example.com',
+      name: 'Remote',
+      type: 'remote',
+      status: 'authenticated',
+      backoffMs: 2000,
+    },
+  ];
+  app._setSources(sources);
+
+  globalThis.fetch = async (url) => {
+    if (url === '/api/sessions') {
+      return { ok: true, json: async () => [{ name: 'local-session' }] };
+    }
+    // Remote returns 401
+    return { ok: false, status: 401, statusText: 'Unauthorized' };
+  };
+
+  await app.pollSessions();
+
+  const remoteSrc = sources.find((s) => s.url === 'https://remote.example.com');
+  assert.strictEqual(remoteSrc.status, 'auth_required', 'remote source should be marked auth_required');
+  assert.ok(!remoteSrc.nextRetryAt, 'auth_required should not set nextRetryAt');
+
+  globalThis.document.getElementById = origGetById;
+  globalThis.document.querySelectorAll = origQSA;
+  globalThis.fetch = undefined;
+  app._setSources([]);
+});
+
+test('pollSessions sets unreachable and applies exponential backoff on network error', async () => {
+  const mockStatusEl = { textContent: '', className: '' };
+  const mockGrid = { innerHTML: '' };
+  const mockEmptyState = { style: {}, classList: { add: () => {}, remove: () => {} } };
+
+  const origGetById = globalThis.document.getElementById;
+  const origQSA = globalThis.document.querySelectorAll;
+  globalThis.document.getElementById = (id) => {
+    if (id === 'connection-status') return mockStatusEl;
+    if (id === 'session-grid') return mockGrid;
+    if (id === 'empty-state') return mockEmptyState;
+    return null;
+  };
+  globalThis.document.querySelectorAll = () => [];
+
+  const sources = [
+    { url: '', name: 'Local', type: 'local', status: 'authenticated', backoffMs: 2000 },
+    {
+      url: 'https://remote.example.com',
+      name: 'Remote',
+      type: 'remote',
+      status: 'authenticated',
+      backoffMs: 2000,
+    },
+  ];
+  app._setSources(sources);
+
+  const beforePoll = Date.now();
+  globalThis.fetch = async (url) => {
+    if (url === '/api/sessions') {
+      return { ok: true, json: async () => [] };
+    }
+    return { ok: false, status: 500, statusText: 'Internal Server Error' };
+  };
+
+  await app.pollSessions();
+
+  const remoteSrc = sources.find((s) => s.url === 'https://remote.example.com');
+  assert.strictEqual(remoteSrc.status, 'unreachable', 'remote source should be marked unreachable');
+  // backoffMs doubles from 2000 → 4000
+  assert.strictEqual(remoteSrc.backoffMs, 4000, 'backoff should double from 2000 to 4000');
+  assert.ok(remoteSrc.nextRetryAt > beforePoll, 'nextRetryAt should be set to a future timestamp');
+  assert.ok(remoteSrc.nextRetryAt <= beforePoll + 4000 + 100, 'nextRetryAt should be roughly now + 4000ms');
+
+  globalThis.document.getElementById = origGetById;
+  globalThis.document.querySelectorAll = origQSA;
+  globalThis.fetch = undefined;
+  app._setSources([]);
+});
+