diff --git a/docs/agents/backlog/playback-qa-1.json b/docs/agents/backlog/playback-qa-1.json
index 078fc023..5f910e39 100644
--- a/docs/agents/backlog/playback-qa-1.json
+++ b/docs/agents/backlog/playback-qa-1.json
@@ -1,9 +1,10 @@
 {
-  "id": "playback-qa-1",
-  "area": "playback-qa",
-  "status": "open",
-  "title": "Qualify local hosted-source fallback with independent regression and browser evidence",
-  "blockedOn": null,
-  "addedOn": "2026-10-20",
-  "filedAt": "0c1dd7e86be3e28edc96aca47f7753a98990dde0"
+ "id": "playback-qa-1",
+ "area": "playback-qa",
+ "status": "in-progress",
+ "title": "Qualify local hosted-source fallback with independent regression and browser evidence",
+ "blockedOn": null,
+ "addedOn": "2026-10-20",
+ "filedAt": "0c1dd7e86be3e28edc96aca47f7753a98990dde0",
+ "notes": "QA granted14:49:35Z/consumed14:49:46Z after request13:43:52Z (65m43 to grant,11s pickup; storage release→dispatch grant39m57 foreground/wakeup lag). Merged unstable7f99c045→124be143; focused4/4,lint11/11 and full env -u NODE_TEST_CONTEXT UNIT_TEST_TIMEOUT_MS=60000 npm test exit0 all429 unit files. Regression025771a8; six isolated mutants rejected/restored. Browser Chromium+Firefox3 scenarios each passed bounded native VP8 decode; zero external requests, no real WebTorrent/full app/wholeStage3 qualification. Browser scheduling intervention recorded. Preparing unchanged normal queue submission and durable landing verification; no new item."
 }
diff --git a/docs/testing/playback-qa-1-evidence.md b/docs/testing/playback-qa-1-evidence.md
new file mode 100644
index 00000000..87d92c7a
--- /dev/null
+++ b/docs/testing/playback-qa-1-evidence.md
@@ -0,0 +1,199 @@
+# playback-qa-1: bounded local fallback qualification
+
+Start UTC: 2026-10-20T13:38:36Z. Baseline: `bbc1be79e941add929c9c51f984778676822b5f2`.
+`git diff 0c1dd7e..HEAD -- js/app/playbackCoordinator.js js/services/playbackService.js`
+was empty; the filed scenario still applies. Product code and existing tests remain read-only.
+
+Plan:
+- Exercise actual coordinator → strategy → playback session, with real magnet derivation/validation.
+- Control probe/media/torrent IO only; check source, handoff payload, surfaced error and settlement.
+- Retain a focused regression only after dispatch approves the proposed approach.
+- Require disabled-fallback mutants to fail, restore scratch product copies, run coordinated normal gates and verify landing ancestry.
+
+## Scratch results
+
+`env -u NODE_TEST_CONTEXT node /tmp/bitvid-playback-qa-1/check.mjs`: exit0,3/3 scenarios
+(404 probe → torrent once; media error → torrent once; both fail → null result/error once).
+Initial scratch setup failed with absent worktree jsdom, then missing app callback; corrected the fixture
+before recording the3/3 result. No product change was made to obtain a pass.
+
+Worktree has no node_modules. Scratch used already-installed main checkout jsdom/playwright read-only;
+no dependency install or public sample download. Native test input was generated locally:
+
+```sh
+ffmpeg -hide_banner -loglevel error -f lavfi -i color=c=blue:s=64x64:r=10 -t 2 -an -c:v libvpx -y /tmp/bitvid-playback-qa-1/clip.webm
+node /tmp/bitvid-playback-qa-1/browser.mjs
+```
+
+Browser script: exit0; Chromium154.0.8037.97 and Firefox146.0.1,3/3 each.
+Both selected torrent once after a real local HEAD404; substituted torrent handler attached the generated
+WebM and awaited native play. Both selected a viable hosted mirror once after HEAD404, with no torrent call.
+Both settled null/error once when the alternate rejected; app session/result promise cleared.
+Native decoding measured64×64, readyState4, currentTime>0:
+
+| Browser | Substituted torrent transport time | Hosted mirror time |
+| --- | ---: | ---: |
+| Chromium |0.001026s |0.002208s |
+| Firefox |0.000372s |0.160829s |
+
+Zero external requests in either browser. HTTP server bound only127.0.0.1:31847;
+all browser requests were origin-filtered; no real torrent client instantiated.
+Browser and server closed in finally blocks, released13:40:46Z. Preview3000 untouched.
+
+Fidelity: real imported product orchestration/magnet code, native video element, real local HTTP404/200,
+native VP8 decoding. Substituted app/modal callbacks and torrent transport; module harness does not boot
+full Application/UI/feed/relay fixture. Local HTTP is a loopback test exception, not HTTPS/CORS qualification.
+No actual WebTorrent, swarm, peer, torrent metadata/file selection or webseed consumption was measured.
+Hash/webseed preservation is at the torrent-handler boundary, not proof of subsequent network use.
+No claim for late stalls after successful startup, HLS, whole Stage3, CPU/RSS, full E2E, signer/wallet or production.
+
+## Coordination and contention
+
+First mailbox read was empty. Claim and inspection started; retention proposal/coordination sent13:39:50Z.
+Dispatch's13:38:29 mail was read only after the browser run; it required expensive-browser slot coordination
+while an admin drain and client gate were active. The bounded module browser run had already finished.
+No resource-contention error was observed in these six scenarios; overlapping gate impact was not measured. This scheduling miss was disclosed to dispatch13:40:48Z; no further browser/full gates will run without clearance.
+Sandbox loopback listen failedEPERM; approved elevated rerun completed in8.31s. No automatic review rejection. Lint also required an approved elevated rerun after git-spawnEPERM.
+Retention approval/full-gate scheduling wait began13:39:50Z; useful independent evidence work continued.
+
+## Reproduce bounded browser check
+
+Generate the clip above. Save the following as `/tmp/bitvid-playback-qa-1/browser.mjs`.
+It uses installed dependencies read-only at the stated main path; adjust only dependency/root paths for another checkout.
+
+```js
+import { createServer } from 'node:http';
+import { readFile } from 'node:fs/promises';
+import { chromium, firefox } from '/home/user/Documents/GitHub/bitvid/node_modules/playwright/index.mjs';
+import assert from 'node:assert/strict';
+const root='/home/user/Documents/GitHub/bitvid-playback-qa';
+const requests=[];
+const server=createServer(async(req,res)=>{
+ requests.push(req.url);
+ if(req.url==='/'){res.setHeader('Content-Type','text/html');res.end('<video muted></video>');return;}
+ if(req.url==='/dead.webm'){res.writeHead(404);res.end();return;}
+ try {
+  const path=req.url==='/clip.webm'?'/tmp/bitvid-playback-qa-1/clip.webm':root+req.url;
+  if(!/^\/(js|config)\/[a-zA-Z0-9/_.-]+$/.test(req.url)&&req.url!='/clip.webm')throw Error('blocked');
+  const data=await readFile(path);
+  res.setHeader('Content-Type',req.url.endsWith('.webm')?'video/webm':'text/javascript');res.end(data);
+ }catch{res.writeHead(404);res.end();}
+});
+try {
+ await new Promise((resolve,reject)=>{server.once('error',reject);server.listen(31847,'127.0.0.1',resolve);});
+ for(const [name,type] of [['chromium',chromium],['firefox',firefox]]){
+  const browser=await type.launch({headless:true,...(name==='chromium'?{executablePath:'/usr/bin/google-chrome',args:['--no-sandbox']}: {})});
+  try{
+   const page=await browser.newPage();const external=[];
+   await page.route('**/*',r=>new URL(r.request().url()).origin==='http://127.0.0.1:31847'?r.continue():(external.push(r.request().url()),r.abort()));
+   await page.goto('http://127.0.0.1:31847');
+   const results=await page.evaluate(async()=>{
+    const {PlaybackService}=await import('/js/services/playbackService.js');
+    const {PlaybackStrategyService}=await import('/js/services/playbackStrategyService.js');
+    const {createPlaybackCoordinator}=await import('/js/app/playbackCoordinator.js');
+    const {deriveTorrentPlaybackConfig}=await import('/js/playbackUtils.js');
+    const {isValidMagnetUri}=await import('/js/utils/magnetValidators.js');
+    localStorage.setItem('unmutedAutoplay','false');
+    const results=[];
+    for(const mode of ['torrent-local-decode','mirror-local-decode','both-fail']){
+     const video=document.querySelector('video');video.pause();video.removeAttribute('src');video.load();
+     const calls=[],errors=[];const hash='ABCDEF0123456789abcdef0123456789ABCDEF01';
+     const url=location.origin+'/dead.webm';const mirror=location.origin+'/clip.webm';
+     const magnet=`magnet:?xt=urn:btih:${hash}`;
+     const service=new PlaybackService({deriveTorrentPlaybackConfig,isValidMagnetUri});
+     const strategy=new PlaybackStrategyService({playbackService:service,logger:{log(){}}});
+     const app={modalVideo:video,currentVideo:{},playbackStrategyService:strategy,videoModal:{updateStatus(){}},
+      waitForCleanup:async()=>{},cancelPendingViewLogging(){},clearActiveIntervals(){},showModalWithPoster(){},
+      teardownVideoElement:v=>v,applyModalLoadingPoster(){},resetTorrentStats(){},preparePlaybackLogging(){},autoplayModalVideo(){},forceRemoveModalPoster(){},showError:x=>errors.push(x),
+      probeUrl:async u=>{calls.push(['probe',u]);const r=await fetch(u,{method:'HEAD'});return {outcome:r.ok?'ok':'bad',status:r.status};},
+      playViaWebTorrent:async(m,o)=>{calls.push(['torrent',m,o]);if(mode==='both-fail')throw Error('local alternate unavailable');video.src=mirror;await video.play();return {substitutedTransport:true};}
+     };
+     const result=await createPlaybackCoordinator({}).playVideoWithFallback.call(app,{url,magnet,...(mode==='mirror-local-decode'?{sources:[mirror,mirror]}:{})});
+     if(result.source){await new Promise((resolve,reject)=>{if(video.currentTime>0)return resolve();video.addEventListener('timeupdate',resolve,{once:true});video.addEventListener('error',reject,{once:true});});}
+     results.push({mode,source:result.source,errors,calls,currentTime:video.currentTime,width:video.videoWidth,height:video.videoHeight,readyState:video.readyState,activeSession:app.activePlaybackSession,activePromise:app.activePlaybackResultPromise});
+    }
+    return results;
+   });
+   for(const r of results){
+    assert.equal(r.source,r.mode==='both-fail'?null:r.mode==='mirror-local-decode'?'url':'torrent');
+    assert.equal(r.calls.filter(c=>c[0]==='torrent').length,r.mode==='mirror-local-decode'?0:1);
+    assert.equal(r.errors.length,r.mode==='both-fail'?1:0);
+    assert.equal(r.activeSession,null);assert.equal(r.activePromise,null);
+    if(r.source){assert.equal(r.width,64);assert.equal(r.height,64);assert.ok(r.currentTime>0);}
+   }
+   assert.deepEqual(external,[]);console.log(JSON.stringify({browser:name,version:browser.version(),results,externalRequests:external.length}));
+  }finally{await browser.close();}
+ }
+ console.log(JSON.stringify({httpRequests:requests}));
+}finally{await new Promise(resolve=>server.close(resolve));}
+```
+
+## Retained regression and verification
+
+Dispatch approved the exact retained4-scenario approach13:41:49Z; read before13:42:54Z.
+`env -u NODE_TEST_CONTEXT node tests/fleet-playback-fallback.test.mjs`: exit0,4 tests/pass4/fail0/cancelled0/skipped0.
+`python3 /tmp/bitvid-playback-qa-1/mutants.py`: exit0; six mutants each rejected exit1.
+Restored scratch test run:4/4, exit0. No product changes in worktree.
+`npm run lint`: initial sandbox attempt exited2 at lint:hex (git spawnEPERM); approved elevated rerun exited0,11/11 scripts.
+Own temporary `node_modules` symlink reused existing main dependencies for lint; no install.
+No full unit/E2E/build started independently; normal queue gate awaits dispatch slot.
+
+Isolated mutation reproduction (copy product/test into the scratch tree first):
+
+```sh
+mkdir -p /tmp/bitvid-playback-qa-1/tree/tests/test-helpers
+cp -R js config /tmp/bitvid-playback-qa-1/tree/
+cp package.json /tmp/bitvid-playback-qa-1/tree/
+cp tests/test-helpers/setup-localstorage.mjs /tmp/bitvid-playback-qa-1/tree/tests/test-helpers/
+cp tests/fleet-playback-fallback.test.mjs /tmp/bitvid-playback-qa-1/tree/tests/
+python3 /tmp/bitvid-playback-qa-1/mutants.py
+env -u NODE_TEST_CONTEXT node /tmp/bitvid-playback-qa-1/tree/tests/fleet-playback-fallback.test.mjs
+```
+
+Save this as the stated mutants.py:
+
+```python
+from pathlib import Path
+import subprocess, os, json
+root=Path('/tmp/bitvid-playback-qa-1/tree')
+mutants=[
+ ('drop-session-cleanup','js/services/playbackStrategyService.js','this.activePlaybackSession = null;\n        if (typeof context.setActivePlaybackSession', '/* deliberately retain session */\n        if (typeof context.setActivePlaybackSession'),
+ ('disable-torrent-fallback','js/services/playbackService.js','if (torrentAttempted) return null;','return null; // deliberately disable alternate\n        if (torrentAttempted) return null;'),
+ ('drop-mirror-forwarding','js/services/playbackStrategyService.js','sources: Array.isArray(options.sources) ? options.sources : [],','sources: [],'),
+ ('corrupt-literal-hash','js/services/playbackService.js','playViaWebTorrent(this.magnetForPlayback, {','playViaWebTorrent(this.magnetForPlayback.toLowerCase(), {'),
+ ('drop-hosted-hint','js/services/playbackService.js','hostedUrlWebSeed: httpsUrl,','hostedUrlWebSeed: "",'),
+ ('drop-terminal-error','js/services/playbackStrategyService.js','context.showError(displayMessage);','/* deliberately suppress terminal UI error */'),
+]
+results=[]
+for name,path,old,new in mutants:
+ p=root/path; original=p.read_text(); assert original.count(old)==1
+ try:
+  p.write_text(original.replace(old,new));
+  r=subprocess.run(['env','-u','NODE_TEST_CONTEXT','node',str(root/'tests/fleet-playback-fallback.test.mjs')],capture_output=True,text=True,timeout=10)
+  Path('/tmp/bitvid-playback-qa-1/'+name+'.log').write_text(r.stdout+r.stderr)
+  assert r.returncode!=0, name+' survived'
+  results.append({'mutant':name,'exit':r.returncode,'failed':[l for l in r.stdout.splitlines() if l.startswith('not ok')]})
+ finally:p.write_text(original)
+print(json.dumps(results,indent=2))
+```
+
+Pre-gate checkpoint: regression commit `025771a84d95c05842193631c1ace70539558368`.
+Merged local unstable into own branch at `acb2fdef3baf74c2526babf79eea8a2451a3aa46`;
+sandbox ORIG_HEAD lock initially read-only, then approved elevated local merge succeeded.
+Post-merge focused check:4/4, exit0; `git diff --check`: exit0. New RULE-CHANGES read.
+Full+submit scheduling explicitly waits behind client then storage per dispatch13:43:52Z.
+
+## Granted merged integration check
+
+Authoritative dispatch mailbox grant header:2026-10-20T14:49:35Z; consumed14:49:46Z.
+Its initial body said14:11; dispatch corrected this explicitly in14:49:55 mail, consumed14:50:25Z.
+Request13:43:52→grant14:49:35=65m43s resource/coordination wait; grant consumption11s.
+Storage release14:09:38→grant14:49:35=39m57s dispatch foreground/wakeup latency, not worker/test time.
+The earlier worker reply interpreted14:11 as intended grant time; this was incorrect. It was a stale body timestamp only, with no14:11 send or delivery delay. Dispatch wake/checkpoint lag39m57s is the valid delay metric; grant consumption was11s.
+
+Merged verified unstable7f99c045 into own branch at `124be14310a314bd4ca99d075a7aacc207c238ac`.
+`env -u NODE_TEST_CONTEXT node tests/fleet-playback-fallback.test.mjs`: exit0,4/4.
+`env -u NODE_TEST_CONTEXT npm run lint`: exit0,11/11 on merged tree (approved outside sandbox for git spawn).
+`git diff --check`: exit0.
+`env -u NODE_TEST_CONTEXT UNIT_TEST_TIMEOUT_MS=60000 npm test`: exit0, all429 unit files passed, including the new regression; completed14:55:44Z. Actual process exit was checked, not a log-reading command. No timeout/failure or assertion changes.
+No browser/build repeat: relevant playback/magnet chain unchanged by predecessor landings.
diff --git a/docs/testing/playback-qa-1-integrity.md b/docs/testing/playback-qa-1-integrity.md
new file mode 100644
index 00000000..fc86cb52
--- /dev/null
+++ b/docs/testing/playback-qa-1-integrity.md
@@ -0,0 +1,64 @@
+# playback-qa-1 test integrity
+
+Approved by dispatch mailbox `20261020T134149-dispatch-c71c3f.md`.
+Scope: new dependency-free `tests/fleet-playback-fallback.test.mjs`; no existing expectations changed.
+
+```yaml
+test_integrity_note:
+  change_type: ["new_tests"]
+  scenarios:
+    - id: SCN-playback-primary-404
+      given: "dual-source video; primary probe returns definitive 404"
+      when: "actual app coordinator invokes strategy and playback session"
+      then: "torrent selected once; literal hash and original/hosted webseeds preserved; source/UI state and session settle"
+    - id: SCN-playback-primary-media-error
+      given: "dual-source video; successful probe followed by media error and stalled events"
+      when: "actual playback watchdog receives the failures"
+      then: "torrent selected once with preserved handoff and cleared session"
+    - id: SCN-playback-viable-mirror
+      given: "primary 404 and duplicated viable hosted mirror"
+      when: "actual playback orchestration tries sources"
+      then: "mirror selected once, URL success/source surfaced, no torrent invocation"
+    - id: SCN-playback-terminal-both-fail
+      given: "primary 404 and alternate handler rejection"
+      when: "actual playback orchestration runs"
+      then: "promise settles with error/null source, one UI error, session/promise released"
+  observable_outcomes:
+    - "app source, returned source/error/alternate instance, status and surfaced errors"
+    - "torrent boundary payload preserves exact original xt/hash and webseed hints"
+    - "ordered probe/media attempts and exactly one alternate selection"
+    - "no active app/strategy session or pending result after settlement"
+  determinism_controls:
+    - "fixed magnets/URLs; no sockets, peers, fetch or external service"
+    - "EventTarget media double emits controlled playing/error/stalled events"
+    - "probe and torrent IO controlled at injected app boundaries"
+    - "real coordinator, strategy, PlaybackService, magnet derivation and validator"
+    - "2s test failure bound; no sleeps/retries or replaced selection/watchdog logic"
+  anti_cheat_rationale:
+    prevents:
+      - "hard-coded source/result without actual alternate invocation"
+      - "over-mocking orchestration or magnet normalization"
+      - "skipping viable mirror or duplicate alternate selection"
+      - "hash corruption, lost hosted hint, suppressed UI error, unclosed session"
+      - "snapshot rubber-stamping and retry/sleep-based flake masking"
+  relaxation:
+    did_relax_any_assertion: false
+    if_true_explain_spec_basis: ""
+```
+
+Six deliberate product mutations were made only in an isolated copy under `/tmp/bitvid-playback-qa-1/tree`.
+Each failed exit1; originals were restored in finally, and the complete original suite passed4/4 again.
+
+| Mutant | Scenarios rejecting it |
+| --- | --- |
+| Disable torrent alternate entirely |404, media error, both fail |
+| Drop mirror forwarding in strategy |viable mirror |
+| Lowercase handoff magnet, corrupting literal mixed-case hash |404, media error, both fail |
+| Erase hostedUrlWebSeed hint |404, media error, both fail |
+| Suppress terminal UI error |both fail |
+| Retain strategy active session on finish |all4 |
+
+Each new scenario rejects at least one mutant. No product mutation was committed.
+
+Fidelity limits and native local decoding results: [evidence](playback-qa-1-evidence.md).
+The retained media double validates orchestration, not a browser decoder or real WebTorrent.
diff --git a/tests/fleet-playback-fallback.test.mjs b/tests/fleet-playback-fallback.test.mjs
new file mode 100644
index 00000000..f1caa08a
--- /dev/null
+++ b/tests/fleet-playback-fallback.test.mjs
@@ -0,0 +1,207 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import "./test-helpers/setup-localstorage.mjs";
+import { createPlaybackCoordinator } from "../js/app/playbackCoordinator.js";
+import { PlaybackStrategyService } from "../js/services/playbackStrategyService.js";
+import { PlaybackService } from "../js/services/playbackService.js";
+import { deriveTorrentPlaybackConfig } from "../js/playbackUtils.js";
+import { isValidMagnetUri } from "../js/utils/magnetValidators.js";
+
+// Real coordinator/strategy/session/magnet helpers; only IO and modal rendering
+// are substituted. This proves orchestration, not native decoding or WebTorrent.
+const primary = "https://localhost/dead.webm";
+const mirror = "https://localhost/mirror.webm";
+const seed = "https://localhost/original.webm";
+const hash = "ABCDEF0123456789abcdef0123456789ABCDEF01";
+const magnet = `magnet:?xt=urn:btih:${hash}&ws=${encodeURIComponent(seed)}`;
+
+class ControlledMedia extends EventTarget {
+  dataset = {};
+  isConnected = true;
+  src = "";
+  readyState = 0;
+  networkState = 0;
+  currentTime = 0;
+  paused = true;
+  error = null;
+  constructor(onPlay) {
+    super();
+    this.onPlay = onPlay;
+  }
+  pause() {
+    this.paused = true;
+  }
+  load() {
+    this.error = null;
+  }
+  removeAttribute(name) {
+    if (name === "src") this.src = "";
+  }
+  async play() {
+    this.onPlay(this);
+  }
+}
+
+async function runScenario(mode) {
+  const probes = [],
+    mediaStarts = [],
+    torrents = [],
+    errors = [],
+    statuses = [];
+  const torrentInstance = { fixture: "alternate-IO" };
+  const video = new ControlledMedia((element) => {
+    mediaStarts.push(element.src);
+    if (element.src === mirror) {
+      element.dispatchEvent(new Event("playing"));
+    } else {
+      // Repeated failures must still lead to just one alternate selection.
+      element.dispatchEvent(new Event("error"));
+      element.dispatchEvent(new Event("stalled"));
+    }
+  });
+  const service = new PlaybackService({
+    deriveTorrentPlaybackConfig,
+    isValidMagnetUri
+  });
+  const strategy = new PlaybackStrategyService({
+    playbackService: service,
+    logger: { log() {} }
+  });
+  const app = {
+    modalVideo: video,
+    currentVideo: {},
+    playbackStrategyService: strategy,
+    videoModal: { updateStatus: (message) => statuses.push(message) },
+    waitForCleanup: async () => {},
+    cancelPendingViewLogging() {},
+    clearActiveIntervals() {},
+    showModalWithPoster() {},
+    teardownVideoElement: (element) => element,
+    applyModalLoadingPoster() {},
+    resetTorrentStats() {},
+    preparePlaybackLogging() {},
+    autoplayModalVideo() {},
+    forceRemoveModalPoster() {},
+    probeUrl: async (url) => {
+      probes.push(url);
+      return mode === "media-error" || url === mirror
+        ? { outcome: "ok", status: 200 }
+        : { outcome: "bad", status: 404 };
+    },
+    playViaWebTorrent: async (uri, options) => {
+      torrents.push({ uri, options });
+      if (mode === "both-fail") throw new Error("local alternate unavailable");
+      return torrentInstance;
+    },
+    showError: (message) => errors.push(message)
+  };
+  const result = await createPlaybackCoordinator({}).playVideoWithFallback.call(
+    app,
+    {
+      url: primary,
+      magnet,
+      ...(mode === "mirror" ? { sources: [primary, mirror, mirror] } : {})
+    }
+  );
+
+  assert.equal(
+    app.activePlaybackSession,
+    null,
+    "finished session released from app"
+  );
+  assert.equal(
+    app.activePlaybackResultPromise,
+    null,
+    "finished promise released from app"
+  );
+  assert.equal(strategy.activePlaybackSession, null);
+  assert.equal(strategy.activePlaybackResultPromise, null);
+  assert.equal(service.currentSession.isActive(), false);
+  // Stale media notifications after settlement must not start another alternate.
+  video.dispatchEvent(new Event("error"));
+  video.dispatchEvent(new Event("stalled"));
+  return {
+    result,
+    probes,
+    mediaStarts,
+    torrents,
+    errors,
+    statuses,
+    app,
+    torrentInstance
+  };
+}
+
+function assertTorrentHandoff(torrents) {
+  assert.equal(torrents.length, 1, "alternate selected exactly once");
+  const { uri, options } = torrents[0];
+  assert.equal(
+    uri.split("&")[0],
+    `magnet:?xt=urn:btih:${hash}`,
+    "literal original xt/hash preserved"
+  );
+  const hints = uri
+    .split("&")
+    .filter((part) => part.startsWith("ws="))
+    .map((part) => decodeURIComponent(part.slice(3)));
+  assert.ok(hints.includes(seed), "original webseed preserved");
+  assert.ok(
+    hints.includes(primary),
+    "hosted webseed preserved in normalized magnet"
+  );
+  assert.equal(options.hostedUrlWebSeed, primary);
+  assert.deepEqual(options.urlList, [seed, primary]);
+}
+
+for (const mode of ["probe-404", "media-error", "both-fail", "mirror"]) {
+  test(
+    `actual playback orchestration: ${mode}`,
+    { timeout: 2000 },
+    async () => {
+      const {
+        result,
+        probes,
+        mediaStarts,
+        torrents,
+        errors,
+        statuses,
+        app,
+        torrentInstance
+      } = await runScenario(mode);
+      assert.deepEqual(
+        probes,
+        mode === "mirror" ? [primary, mirror] : [primary]
+      );
+      assert.deepEqual(
+        mediaStarts,
+        mode === "media-error" ? [primary] : mode === "mirror" ? [mirror] : []
+      );
+      if (mode === "mirror") {
+        assert.equal(result.source, "url");
+        assert.equal(app.playSource, "url");
+        assert.equal(
+          torrents.length,
+          0,
+          "viable hosted mirror prevents torrent fallback"
+        );
+        assert.deepEqual(errors, []);
+        assert.ok(statuses.includes("✅ Streaming from hosted URL"));
+      } else {
+        assertTorrentHandoff(torrents);
+        if (mode === "both-fail") {
+          assert.equal(result.source, null);
+          assert.ok(result.error instanceof Error);
+          assert.equal(app.playSource, null);
+          assert.equal(errors.length, 1, "one surfaced terminal error");
+          assert.match(errors[0], /^Playback error:/);
+        } else {
+          assert.equal(result.source, "torrent");
+          assert.equal(result.torrentInstance, torrentInstance);
+          assert.equal(app.playSource, "torrent");
+          assert.deepEqual(errors, []);
+          assert.ok(statuses.includes("Switching to WebTorrent..."));
+        }
+      }
+    }
+  );
+}