Merge retry hardening with DSP cache opt-in

frontend/app.js

@@ -60,12 +60,14 @@ async function call(zeroName, tauriName, payload = {}) {
 
 // Generic fetch wrapper — returns parsed JSON or throws with a human message.
 async function webFetch(path, opts = {}) {
+  if ((opts.method || 'GET').toUpperCase() === 'GET' && window.AsyncGuard?.getJson)
+    return AsyncGuard.getJson(path, opts, {
+      // Some upstream failures are represented by HTTP 200 + {ok:false}; do
+      // not expose those transient responses as a manual Retry state either.
+      retryResult: value => value?.ok === false && /\b(?:408|425|429|5\d\d)\b|temporar|timed?\s*out|network|connection|upstream|unavailable|available right now/i.test(String(value.error || value.message || '')),
+    });
   const res = await fetch(path, opts);
-  if (!res.ok) {
+  if (!res.ok) throw new Error(`HTTP ${res.status}`);
-    let msg = `HTTP ${res.status}`;
-    try { const j = await res.json(); msg = j.error || msg; } catch { /* non-JSON */ }
-    throw new Error(msg);
-  }
   return res.json();
 }
 
@@ -573,7 +575,7 @@ const API = {
     ? webFetch(`/api/search?q=${encodeURIComponent(query)}${refresh ? '&refresh=1' : ''}`)
     : call('yt.search', 'yt_search', { query }),
   related: (meta, { refresh = false } = {}) => WEB && /^[\w-]{11}$/.test(meta.id)
-    ? fetch(`/api/related?${new URLSearchParams({ videoId: meta.id, title: meta.title || '', channel: meta.channel || meta.artist || '', ...(refresh ? { refresh: '1' } : {}) })}`).then(response => response.json())
+    ? webFetch(`/api/related?${new URLSearchParams({ videoId: meta.id, title: meta.title || '', channel: meta.channel || meta.artist || '', ...(refresh ? { refresh: '1' } : {}) })}`)
     : API.search(meta.title || meta.channel, { refresh }),
   // Videos the server already knows — answers fast while the real search loads.
   searchLocal: (query) => WEB
@@ -8666,9 +8668,7 @@ const RUNNING_BUILD = (() => {
 let _knownBuildTag = null;
 
 async function fetchServerBuild() {
-  const res = await fetch('/api/version', { cache: 'no-store' });
+  const data = await webFetch('/api/version', { cache: 'no-store' });
-  if (!res.ok) return null;
-  const data = await res.json();
   return data.buildTag || null;
 }
 

frontend/asset-sync-core.js

@@ -162,7 +162,7 @@
   const completionKey = manifest => '/__ytp_completion/' + manifest.buildTag;
   async function complete(manifest, { cache, fetchFn, cycles = 4, now = Date.now, optIns,
     sleep = ms => new Promise(resolve => setTimeout(resolve, ms)), baseDelay = 1000,
-    maxDelay = 30000, notify = () => {}, force = false } = {}) {
+    maxDelay = 30000, notify = () => {}, force = false, concurrency = 1 } = {}) {
     const key = completionKey(manifest), saved = await cache.match(key);
     let job = saved ? await saved.json() : { failures: 0, nextRetryAt: 0 };
     const selectedOptIns = optIns || await readOptIns(cache);
@@ -177,7 +177,7 @@
     for (let cycle = 0; cycle < cycles; cycle++) {
       await publish(true);
       let error;
-      try { await syncAssets(manifest, { cache, fetchFn, all: true, optIns: selectedOptIns }); }
+      try { await syncAssets(manifest, { cache, fetchFn, all: true, optIns: selectedOptIns, concurrency }); }
       catch (failure) { error = failure; }
       snapshot = await completeness(manifest, cache, { optIns: selectedOptIns });
       if (snapshot.offlineReady) { job.failures = 0; job.nextRetryAt = 0; job.error = null; await publish(false); return job; }

frontend/asset-sync-core.test.js

@@ -96,6 +96,13 @@ test('overlapping layout and completion jobs share a six-download ceiling',async
  assert.ok(peak<=6);assert.ok([...calls.values()].every(count=>count===1));
 });
 
+test('offline completion keeps its own network concurrency to one',async()=>{
+ const c=cache(),m=manifest();let active=0,peak=0;
+ for(let i=0;i<12;i++){const p='/complete'+i+'.js';m.files[p]={h:String(i)};}
+ const fetchFn=async u=>{active++;peak=Math.max(peak,active);await new Promise(r=>setTimeout(r,2));active--;return response(u.split('=')[1]);};
+ await core.complete(m,{cache:c,fetchFn});assert.equal(peak,1);
+});
+
 test('blocking commit never waits on an optional file readiness probe',{timeout:1000},async()=>{
  const c=cache(),m=manifest();m.files['/extra.js']={h:'extra'};m.groups.extra={files:['/extra.js'],background:true,contract:1};
  await c.put('/a.js?v=a',response('a'));await c.put('/index.html?v=b',response('b'));

frontend/async-guard.js

@@ -35,7 +35,68 @@
     }
   }
 
-  const AsyncGuard = { runExclusive };
+  const wait = ms => new Promise(resolve => setTimeout(resolve, ms));
+  async function retry(task, { attempts = 3, delay = attempt => attempt === 1 ? 350 : 1000,
+    shouldRetry = () => true, sleep = wait } = {}) {
+    let last;
+    for (let attempt = 1; attempt <= Math.max(1, attempts); attempt++) {
+      try { return await task(attempt); }
+      catch (error) {
+        last = error;
+        if (attempt >= attempts || !shouldRetry(error, attempt)) throw error;
+        await sleep(delay(attempt));
+      }
+    }
+    throw last;
+  }
+
+  // Retry only idempotent GETs. Keep the timeout active through JSON parsing so
+  // a stalled response body is treated like a stalled connection.
+  async function getJson(url, options = {}, config = {}) {
+    const fetchFn = config.fetch || root.fetch?.bind(root);
+    if (!fetchFn) throw new Error('fetch is unavailable');
+    if ((options.method || 'GET').toUpperCase() !== 'GET') throw new Error('Retry helper only accepts GET');
+    const attempts = config.attempts ?? 3, timeoutMs = config.timeoutMs ?? 20000;
+    return retry(async () => {
+      const controller = typeof AbortController === 'function' ? new AbortController() : null;
+      let timedOut = false, timer, externalAbort;
+      const external = options.signal;
+      if (controller && external) {
+        if (external.aborted) throw external.reason || new DOMException('Aborted', 'AbortError');
+        externalAbort = () => controller.abort(external.reason);
+        external.addEventListener('abort', externalAbort, { once: true });
+      }
+      if (controller && timeoutMs > 0) timer = setTimeout(() => { timedOut = true; controller.abort(); }, timeoutMs);
+      try {
+        const response = await fetchFn(url, { ...options, ...(controller ? { signal: controller.signal } : {}) });
+        if ([408, 425, 429].includes(response.status) || response.status >= 500) {
+          const error = new Error(`HTTP ${response.status}`); error.retryable = true; throw error;
+        }
+        if (!response.ok) {
+          let message = `HTTP ${response.status}`;
+          try { message = (await response.json()).error || message; } catch {}
+          const error = new Error(message); error.retryable = false; throw error;
+        }
+        const value = await response.json();
+        if (config.retryResult?.(value)) {
+          const error = new Error(value.error || value.message || 'Temporary API failure');
+          error.retryable = true;
+          throw error;
+        }
+        return value;
+      } catch (error) {
+        if (external?.aborted) throw error;
+        if (timedOut) { const timeout = new Error('Request timed out'); timeout.retryable = true; throw timeout; }
+        if (error.retryable === undefined) error.retryable = true;
+        throw error;
+      } finally {
+        if (timer) clearTimeout(timer);
+        if (external && externalAbort) external.removeEventListener('abort', externalAbort);
+      }
+    }, { attempts, shouldRetry: error => error.retryable !== false, sleep: config.sleep || wait });
+  }
+
+  const AsyncGuard = { runExclusive, retry, getJson };
 
   if (typeof module !== 'undefined' && module.exports) {
     module.exports = AsyncGuard;

frontend/async-guard.test.js

@@ -60,6 +60,55 @@ test('frees the key after failure so a retry is possible', async () => {
   assert.strictEqual(out, 'ok');
 });
 
+test('bounded GET retries recover transient network and server failures', async () => {
+  const { getJson } = require('./async-guard');
+  let calls = 0;
+  const result = await getJson('/api/search', {}, { sleep: async () => {}, fetch: async () => {
+    calls++;
+    if (calls === 1) throw new TypeError('connection reset');
+    if (calls === 2) return new Response('{}', { status: 503 });
+    return Response.json({ ok: true, results: [] });
+  } });
+  assert.equal(result.ok, true);
+  assert.equal(calls, 3);
+});
+
+test('GET retry stops at the bound and does not retry permanent HTTP errors', async () => {
+  const { getJson } = require('./async-guard');
+  let calls = 0;
+  await assert.rejects(getJson('/api/search', {}, { sleep: async () => {}, fetch: async () => {
+    calls++; return new Response('{}', { status: 404 });
+  } }), /HTTP 404/);
+  assert.equal(calls, 1);
+  await assert.rejects(getJson('/api/search', {}, { attempts: 2, sleep: async () => {}, fetch: async () => {
+    calls++; throw new TypeError('offline');
+  } }), /offline/);
+  assert.equal(calls, 3);
+});
+
+test('retryable API error payloads recover but permanent application errors do not retry', async () => {
+  const { getJson } = require('./async-guard'); let calls = 0;
+  const retryResult = value => value?.ok === false && /temporarily unavailable/i.test(value.error || '');
+  const result = await getJson('/api/streams', {}, { retryResult, sleep: async () => {}, fetch: async () => {
+    calls++;
+    return Response.json(calls === 1 ? { ok: false, error: 'temporarily unavailable' } : { ok: true, data: [] });
+  } });
+  assert.equal(result.ok, true); assert.equal(calls, 2);
+  calls = 0;
+  const absent = await getJson('/api/streams', {}, { retryResult, sleep: async () => {}, fetch: async () => { calls++; return Response.json({ ok: false, error: 'video not found' }); } });
+  assert.equal(absent.ok, false); assert.equal(calls, 1);
+});
+
+test('timed out GET bodies retry within the configured bound', async () => {
+  const { getJson } = require('./async-guard'); let calls = 0;
+  const result = await getJson('/api/related', {}, { attempts: 2, timeoutMs: 5, sleep: async () => {}, fetch: async (_url, { signal }) => {
+    calls++;
+    if (calls === 1) return new Promise((resolve, reject) => signal.addEventListener('abort', () => reject(new DOMException('aborted', 'AbortError')), { once: true }));
+    return Response.json({ ok: true });
+  } });
+  assert.equal(result.ok, true); assert.equal(calls, 2);
+});
+
 test('supports a synchronous fn', async () => {
   const set = new Set();
   const out = await runExclusive(set, 's', () => 7);

frontend/lazy.js

@@ -6,6 +6,7 @@
   try { manifest = JSON.parse(doc.getElementById('ytp-assets').textContent); }
   catch { return; } // The index must supply this map; never fetch one during boot.
   const assets = new Map(), groups = new Map(), hooks = new Map();
+  let warmScheduled = false;
   const css = new Set([...doc.querySelectorAll('link[data-lazy-css]')].map(link => link.dataset.lazyCss));
   const selected = new Map();
   const url = path => selected.get(path) || (manifest.files[path]?.h ? path + '?v=' + manifest.files[path].h : './' + path.replace(/^\//,''));
@@ -50,14 +51,18 @@
     const style = /\.css$/.test(path);
     if (style && css.has(path)) return Promise.resolve();
     if (!style && !/\.js$/.test(path)) return Promise.resolve(); // workers/imports/fonts are not page scripts
-    const task = new Promise((resolve, reject) => {
+    const loadOnce = () => new Promise((resolve, reject) => {
       const node = doc.createElement(style ? 'link' : 'script');
+      const timer = setTimeout(() => { node.remove?.(); reject(new Error('Timed out loading ' + path)); }, 20000);
       if (style) { node.rel = 'stylesheet'; node.href = url(path); }
       else { node.async = false; node.src = url(path); }
-      node.onload = resolve;
+      node.onload = () => { clearTimeout(timer); resolve(); };
-      node.onerror = () => reject(new Error('Unable to load ' + path));
+      node.onerror = () => { clearTimeout(timer); node.remove?.(); reject(new Error('Unable to load ' + path)); };
       doc.head.append(node);
     });
+    const task = root.AsyncGuard?.retry
+      ? root.AsyncGuard.retry(loadOnce, { attempts: 3 })
+      : loadOnce();
     assets.set(path, task);
     task.catch(() => assets.delete(path));
     return task;
@@ -100,10 +105,17 @@
       else root.navigator.serviceWorker?.getRegistration().then(send).catch(()=>{});
     },
     warm() {
-      if (!root.navigator.serviceWorker || root.navigator.onLine === false) return;
+      if (warmScheduled || !root.navigator.serviceWorker || root.navigator.onLine === false) return;
-      root.navigator.serviceWorker.ready.then(reg => {
+      warmScheduled = true;
-        for (const worker of new Set([reg.active, reg.waiting])) worker?.postMessage({type:'COMPLETE_ASSETS'});
+      const start = () => {
-      }).catch(()=>{});
+        warmScheduled = false;
+        if(root.navigator.onLine === false)return;
+        root.navigator.serviceWorker.ready.then(reg => {
+          for (const worker of new Set([reg.active, reg.waiting])) worker?.postMessage({type:'COMPLETE_ASSETS'});
+        }).catch(()=>{});
+      };
+      if (root.requestIdleCallback) root.requestIdleCallback(start, { timeout: 8000 });
+      else setTimeout(start, 5000);
     },
     onLoad(name, fn) {
       if(api.loaded(name)) { Promise.resolve().then(fn).catch(error=>{if(root.CustomEvent)root.dispatchEvent?.(new root.CustomEvent('ytp-lazy-error',{detail:{group:name,error}}));}); return; }

frontend/lazy.test.js

@@ -7,7 +7,7 @@ function fixture(current, held = [], appCache = false, userAgent = 'AppleWebKit/
   const manifest = { buildTag: 'own', appCache, groups: { core: { files: [] }, 'layout:classic': { files: ['/classic.css'] }, 'layout:glass-stage': { files: ['/glass.css', '/one.js', '/two.js'] }, 'feature:test': { contract:1, files: ['/one.js', '/two.js'] } }, files: { '/app.js':{h:'a'}, '/classic.css': {h:'c'}, '/glass.css':{h:'g'}, '/one.js':{h:'1'}, '/two.js':{h:'2'} } };
   const doc = { readyState:'loading', documentElement: { dataset:{} }, getElementById: () => ({ textContent:JSON.stringify(manifest) }), querySelectorAll: () => [], createElement: tag => ({ tagName:tag.toUpperCase() }), write: value => writes.push(value), addEventListener: (t,f) => listeners[t]=f };
   doc.head = { append: node => { inserted.push(node); queueMicrotask(() => node.onload?.()); } };
-  const root = { document:doc, localStorage:{ getItem:() => '{"settings":{"layout":"glass-stage"}}' }, console, Promise, URL, crypto:{subtle:{}}, fetch:async key=>{fetched.push(key);return new Response('app');}, setTimeout, clearTimeout, navigator:{userAgent,serviceWorker:{ready:Promise.resolve({}),controller:controlled?{}:null,addEventListener(){}}}, addEventListener(){} };
+  const root = { document:doc, localStorage:{ getItem:() => '{"settings":{"layout":"glass-stage"}}' }, console, Promise, URL, crypto:{subtle:{}}, AsyncGuard:require('./async-guard'), requestIdleCallback:fn=>{root.__idle=fn;}, fetch:async key=>{fetched.push(key);return new Response('app');}, setTimeout, clearTimeout, navigator:{userAgent,serviceWorker:{ready:Promise.resolve({}),controller:controlled?{}:null,addEventListener(){}}}, addEventListener(){} };
   if (current) root.caches = { open: async () => ({ match: async key => key === '/__ytp_asset_state' ? new Response(JSON.stringify({current})) : held.includes(key) ? new Response('', {headers:{'X-Asset-Hash':key.split('=')[1]}}) : undefined }) };
   root.window=root; root.globalThis=root;
   vm.runInNewContext(readFileSync(require.resolve('./lazy.js'),'utf8'), root);
@@ -27,11 +27,13 @@ test('lazy groups execute ordered classic scripts once, sharing concurrent calls
   await root.Lazy.load('layout:glass-stage');
   assert.equal(inserted.filter(n=>n.tagName==='SCRIPT').length,2);
 });
-test('failed injection can retry and proxy dispatches only after execution', async () => {
+test('transient script injection failure retries before proxy dispatch', async () => {
   const {root,inserted}=fixture();
   const append=root.document.head.append;
-  root.document.head.append=n=>{inserted.push(n);queueMicrotask(()=>n.onerror?.());};
+  let first=true;
-  await assert.rejects(root.Lazy.load('feature:test'),/one.js/);
+  root.document.head.append=n=>{inserted.push(n);queueMicrotask(()=>{if(first){first=false;n.onerror?.();}else n.onload?.();});};
+  await root.Lazy.load('feature:test');
+  assert.equal(inserted.length,3,'first file is retried, then the second file loads');
   root.document.head.append=append;
   root.TestApi={open:value=>value+1};
   const proxy=root.Lazy.proxy('feature:test',['open'],'TestApi');
@@ -92,6 +94,8 @@ test('online launches request worker completion even with Save-Data and skip off
  f.root.navigator.connection={saveData:true};f.root.navigator.onLine=true;
  f.root.navigator.serviceWorker={ready:Promise.resolve({active,waiting})};
  f.root.Lazy.warm();await Promise.resolve();
+ assert.equal(sent.length,0,'warming waits until the page is idle');
+ f.root.__idle();await Promise.resolve();
  assert.deepEqual(sent.map(m=>m.type),['COMPLETE_ASSETS','COMPLETE_ASSETS']);
  f.root.navigator.onLine=false;f.root.Lazy.warm();await Promise.resolve();assert.equal(sent.length,2);
 });

frontend/sw.js

@@ -265,7 +265,8 @@ self.addEventListener('fetch', (e) => {
     return;
   }
 
-  if (ASSET_SYNC && request.mode === 'navigate') e.waitUntil(completeAssets());
+  // The page schedules completion after first paint/idle via Lazy.warm(). Do
+  // not start a six-file background burst from this foreground fetch event.
 
   // Only intercept GET/HEAD — let POST (sync endpoint) go through unmodified
   if (request.method !== 'GET' && request.method !== 'HEAD') return;
@@ -597,8 +598,8 @@ async function activateAssets() {
   for (const req of await cache.keys()) if(new URL(req.url).pathname.startsWith('/__ytp_candidate/')) await cache.delete(req);
   await self.clients.claim();
   if(old && old.current.buildTag !== m.buildTag) for(const c of await self.clients.matchAll({type:'window',includeUncontrolled:true})) c.postMessage({type:'SW_UPDATE_AVAILABLE',version:VERSION});
-  // Completion owns a message-event lifetime, not the activation barrier.
+  // Resume completion after activation, but with one request at a time so
-  // In particular, a legacy client's four-second reload must not wait for it.
+  // foreground navigation retains most of the available bandwidth.
   self.registration.active.postMessage({ type: 'COMPLETE_ASSETS' });
   try { console.info('[asset-sync] storage', await self.navigator.storage.estimate()); } catch {}
 }

perf/README.md

@@ -496,3 +496,17 @@ control matrix: Chromium and WebKit, all four layouts, dark/light/contrast, and
 geometry, themed selects and switches, the clipped native file picker, and
 button wrapping; desktop screenshots and measurements are written to
 `plans/settings-shots/`.
+
+## Transient retry verification
+
+`retry.mjs` starts the real Bun server behind the local traffic-shaping proxy, then
+injects one HTTP 503 into search, one dropped related-video request, and one lazy
+chunk load failure. Each path must recover automatically without exposing the
+manual related/player Retry affordance. It runs Chromium and WebKit by default;
+choose `--browser chromium|webkit` and `--profile lte|lossy|unthrottled` to narrow
+it. Retry logic is limited to idempotent GET requests and chunk loads; explicit
+save/retry POST actions remain user initiated.
+
+```bash
+node perf/retry.mjs --browser all --profile lossy
+```

perf/retry.mjs

@@ -0,0 +1,108 @@
+#!/usr/bin/env node
+// Foreground transient-failure regression check over the real Bun server and
+// shaped local proxy. Injects one 503/connection drop, then requires recovery
+// without exposing the application's manual Retry/error affordances.
+import assert from 'node:assert/strict';
+import { spawn } from 'node:child_process';
+import { cpSync, mkdirSync, rmSync } from 'node:fs';
+import { join, resolve } from 'node:path';
+import { createServer } from 'node:net';
+import { chromium, webkit } from 'playwright';
+import { createThrottleProxy } from './proxy.mjs';
+
+const repo = resolve(new URL('..', import.meta.url).pathname);
+const scratch = join(repo, 'perf/.tmp/retry');
+const profile = process.argv.includes('--profile') ? process.argv[process.argv.indexOf('--profile') + 1] : 'lossy';
+const engines = process.argv.includes('--browser') ? process.argv[process.argv.indexOf('--browser') + 1] : 'all';
+assert.ok(['all', 'chromium', 'webkit'].includes(engines));
+rmSync(scratch, { recursive: true, force: true }); mkdirSync(scratch, { recursive: true });
+const results = [];
+const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));
+async function freePort() { const s = createServer(); await new Promise(r => s.listen(0, '127.0.0.1', r)); const p = s.address().port; await new Promise(r => s.close(r)); return p; }
+async function poll(fn, timeout = 30000) { const end = Date.now() + timeout; while (Date.now() < end) { if (await fn()) return true; await sleep(100); } return false; }
+
+for (const engine of engines === 'all' ? ['chromium', 'webkit'] : [engines]) {
+  const cwd = join(scratch, engine); mkdirSync(cwd); cpSync(join(repo, 'frontend'), join(cwd, 'public'), { recursive: true });
+  const port = await freePort(); let log = '';
+  const child = spawn('bun', [join(repo, 'server/server.js')], { cwd, env: { ...process.env, PORT: String(port), ASSET_HASHING: '1', ASSET_SYNC: '1', BUILD_TAG: '', DB_PATH: join(cwd, 'db.sqlite'), DATA_DIR: join(cwd, 'data'), MEDIA_DIR: join(cwd, 'media'), UPLOAD_DIR: join(cwd, 'uploads') }, stdio: ['ignore', 'pipe', 'pipe'] });
+  for (const stream of [child.stdout, child.stderr]) stream.on('data', chunk => log = (log + chunk).slice(-8000));
+  let browser, context, proxy;
+  const result = { engine, profile, injected: [], recovered: [], visibleErrors: [] }; results.push(result);
+  try {
+    if (!await poll(async () => { try { return (await fetch(`http://127.0.0.1:${port}/api/version`)).ok; } catch { return false; } })) throw Error(`server failed: ${log}`);
+    proxy = createThrottleProxy({ targetPort: port, profile }); proxy.startTracking();
+    const origin = `http://127.0.0.1:${await proxy.listen()}`;
+    browser = await ({ chromium, webkit })[engine].launch({ headless: true });
+    context = await browser.newContext({ serviceWorkers: 'block' });
+    await context.route('**/*', route => route.request().url().startsWith(origin) ? route.continue() : route.abort());
+    const page = await context.newPage();
+    page.on('console', msg => { if (msg.type() === 'error') result.visibleErrors.push(msg.text()); });
+    page.on('pageerror', error => result.visibleErrors.push(error.message));
+
+    const searchUrl = '**/api/search?q=retry-transport-test*'; let searchCalls = 0;
+    await context.route(searchUrl, async route => {
+      searchCalls++; result.injected.push({ path: '/api/search', attempt: searchCalls, fault: searchCalls === 1 ? '503' : null });
+      if (searchCalls === 1) return route.fulfill({ status: 503, contentType: 'application/json', body: JSON.stringify({ error: 'temporary proxy fault' }) });
+      return route.fulfill({ contentType: 'application/json', body: JSON.stringify({ ok: true, results: [{ id: 'abcdefghijk', title: 'Retry fixture result', channel: 'Harness', duration: 60, thumbnail: '' }] }) });
+    });
+    await page.goto(origin);
+    await page.waitForFunction(() => typeof data !== 'undefined' && document.querySelector('#searchInput'));
+    let versionCalls = 0;
+    await context.route('**/api/version', async route => {
+      versionCalls++; result.injected.push({ path: '/api/version', attempt: versionCalls, fault: versionCalls === 1 ? '503' : null });
+      if (versionCalls === 1) return route.fulfill({ status: 503, contentType: 'application/json', body: JSON.stringify({ error: 'temporary version check failure' }) });
+      return route.fulfill({ contentType: 'application/json', body: JSON.stringify({ buildTag: 'retry-harness' }) });
+    });
+    assert.equal(await page.evaluate(() => fetchServerBuild()), 'retry-harness');
+    assert.equal(versionCalls, 2, `${engine}: update version check did not retry`);
+    result.recovered.push({ path: '/api/version', attempts: versionCalls });
+
+    await page.locator('#searchInput').fill('retry-transport-test'); await page.locator('#searchForm').evaluate(form => form.requestSubmit());
+    await page.locator('.card').filter({ hasText: 'Retry fixture result' }).waitFor({ timeout: 25000 });
+    result.recovered.push({ path: '/api/search', attempts: searchCalls });
+    assert.equal(searchCalls, 2, `${engine}: search did not retry exactly once`);
+    assert.equal(await page.locator('.retry-btn,.related-retry').count(), 0, `${engine}: transient search exposed a manual retry`);
+
+    let streamCalls = 0;
+    await context.route('**/api/streams?v=abcdefghijk*', async route => {
+      streamCalls++; result.injected.push({ path: '/api/streams', attempt: streamCalls, fault: streamCalls === 1 ? '503' : null });
+      if (streamCalls === 1) return route.fulfill({ status: 503, contentType: 'application/json', body: JSON.stringify({ error: 'temporary upstream failure' }) });
+      return route.fulfill({ contentType: 'application/json', body: JSON.stringify({ ok: true, data: { meta: { id: 'abcdefghijk', title: 'Stream fixture' }, qualities: [] } }) });
+    });
+    const streams = await page.evaluate(() => API.getStreams('abcdefghijk'));
+    assert.equal(streamCalls, 2, `${engine}: stream lookup did not retry`);
+    assert.equal(streams.ok, true);
+    result.recovered.push({ path: '/api/streams', attempts: streamCalls });
+
+    let relatedCalls = 0;
+    await context.route('**/api/related?*', async route => {
+      relatedCalls++; result.injected.push({ path: '/api/related', attempt: relatedCalls, fault: relatedCalls === 1 ? 'connection-reset' : null });
+      if (relatedCalls === 1) return route.abort('failed');
+      return route.fulfill({ contentType: 'application/json', body: JSON.stringify({ ok: true, results: [{ id: 'lmnopqrstuv', title: 'Related recovered', channel: 'Harness' }] }) });
+    });
+    const relatedState = await page.evaluate(async () => {
+      current = { meta: { id: 'abcdefghijk', title: 'Retry fixture result', channel: 'Harness' } };
+      await loadRelated(); return relatedState.status;
+    });
+    assert.equal(relatedCalls, 2, `${engine}: related discovery did not retry`);
+    assert.equal(relatedState, 'ready');
+    assert.equal(await page.locator('.related-retry').count(), 0, 'transient failure must not expose manual Retry');
+    result.recovered.push({ path: '/api/related', attempts: relatedCalls });
+
+    let chunkCalls = 0;
+    await context.route('**/video-edit.js?v=*', async route => {
+      chunkCalls++; result.injected.push({ path: '/video-edit.js', attempt: chunkCalls, fault: chunkCalls === 1 ? 'connection-reset' : null });
+      if (chunkCalls === 1) return route.abort('failed');
+      return route.continue();
+    });
+    await page.evaluate(() => Lazy.load('feature:video-edit'));
+    assert.equal(chunkCalls, 2, `${engine}: lazy chunk did not retry`);
+    assert.equal(await page.locator('.retry-btn,.related-retry').count(), 0);
+    result.recovered.push({ path: '/video-edit.js', attempts: chunkCalls });
+    const unexpected = result.visibleErrors.filter(message => !/Failed to load resource|Load failed/.test(message));
+    assert.deepEqual(unexpected, [], `${engine}: page errors after transient recovery`);
+    console.log(JSON.stringify(result));
+  } catch (error) { console.error(engine, log); throw error; }
+  finally { await context?.close(); await browser?.close(); await proxy?.close?.(); child.kill('SIGTERM'); }
+}
+console.log(`Retry recovery passed (${results.length} engine(s), ${profile}).`);