Make fewer IQ Bible calls

- Load the narrator list only when the audio dropdown is opened
- Keep today's verse and devotional in memory for an hour (not saved)
- Back off for a minute after 'allowance used up' or unreachable; keep 'nothing here' answers
- Server shares one upstream call between identical simultaneous requests (nothing stored)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

server/iqbible.js

@@ -89,6 +89,24 @@ async function cacheTtl(headers, isText) {
 const cache = new Map(); // key -> { at, status, type, body }
 const CACHE_MAX = 1500;
 
+// Requests for the same thing that arrive while one is already on its way share that one call. Nothing is kept
+// afterwards (that would be caching), so this spends less of the allowance without touching the API's terms.
+const inflight = new Map(); // upstream path -> Promise of { status, type, body, retryAfter }
+function fetchOnce(key, headers) {
+  let p = inflight.get(key);
+  if (!p) {
+    p = (async () => {
+      const upstream = await fetch(`${BASE()}${key}`, { headers, signal: AbortSignal.timeout(20_000) });
+      return {
+        status: upstream.status, ok: upstream.ok, retryAfter: upstream.headers.get('retry-after'),
+        type: upstream.headers.get('content-type') || 'application/json', body: Buffer.from(await upstream.arrayBuffer()),
+      };
+    })().finally(() => inflight.delete(key));
+    inflight.set(key, p);
+  }
+  return p;
+}
+
 const hits = new Map(); // `${userId}:${bucket}` -> { n, resetAt }
 function overLimit(userId, heavy) {
   const bucket = heavy ? 'h' : 'n';
@@ -119,12 +137,11 @@ export function registerIqBibleRoutes(app, requireAuth) {
       return;
     }
     try {
-      const upstream = await fetch(`${BASE()}${target.key}`, { headers, signal: AbortSignal.timeout(20_000) });
-      const body = Buffer.from(await upstream.arrayBuffer());
-      const type = upstream.headers.get('content-type') || 'application/json';
+      const upstream = await fetchOnce(target.key, headers);
+      const { body, type } = upstream;
       if (upstream.status === 401) return res.status(502).json({ error: 'The IQ Bible key was rejected. Check IQBIBLE_API_KEY.' });
       if (upstream.status === 429) {
-        const retry = upstream.headers.get('retry-after');
+        const retry = upstream.retryAfter;
         if (retry) res.set('Retry-After', retry);
         return res.status(429).json({ error: 'The IQ Bible allowance is used up for now. Try again later.' });
       }

server/iqbible.test.js

@@ -1,5 +1,5 @@
 // @vitest-environment node
-import { test, expect } from 'vitest';
+import { test, expect, vi } from 'vitest';
 import { resolveIqPath } from './iqbible.js';
 
 test('only listed IQ Bible routes are reachable', () => {
@@ -32,3 +32,30 @@ test('only verse and chapter text counts as cacheable text', async () => {
   expect(isTextPath('/commentaries/gill/JHN/3')).toBe(false);
   expect(resolveIqPath('/bibles/parallel', { v: 'eng_kjv,spa_rv' })).not.toBeNull();
 });
+
+test('identical requests made at the same moment share one upstream call, and nothing is kept afterwards', async () => {
+  vi.resetModules();
+  process.env.IQBIBLE_API_KEY = 'k';
+  const realFetch = globalThis.fetch;
+  let upstreamCalls = 0;
+  vi.stubGlobal('fetch', vi.fn(async (url, opts) => {
+    if (String(url).startsWith('http://localhost')) return realFetch(url, opts); // the test's own requests
+    upstreamCalls += 1;
+    await new Promise((r) => setTimeout(r, 30));
+    return new Response(JSON.stringify({ data: 1 }), { status: 200, headers: { 'content-type': 'application/json' } });
+  }));
+  const { registerIqBibleRoutes } = await import('./iqbible.js');
+  const express = (await import('express')).default;
+  const app = express();
+  app.use((req, _res, next) => { req.session = { userId: 'u1' }; next(); });
+  registerIqBibleRoutes(app, (_req, _res, next) => next());
+  const srv = await new Promise((resolve) => { const s = app.listen(0, () => resolve(s)); });
+  const url = `http://localhost:${srv.address().port}/api/iq/devotionals/today`;
+  try {
+    const together = await Promise.all([realFetch(url), realFetch(url), realFetch(url)]);
+    expect(together.map((r) => r.status)).toEqual([200, 200, 200]);
+    expect(upstreamCalls).toBe(1);
+    await realFetch(url); // afterwards: not remembered, so it asks again
+    expect(upstreamCalls).toBe(2);
+  } finally { srv.close(); vi.unstubAllGlobals(); delete process.env.IQBIBLE_API_KEY; }
+});