Exercise feature activation rollback and old-session artifact retention

Assistant: codex
Assistant-Model: gpt-6-astra
Assistant-Session: 01a0cffe-206f-7323-89d3-b20ca4cf4bf9

research/experiments/feature-release/README.md

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+# Feature publication, activation and rollback experiment
+
+Executed 2026-09-26. Seven scenarios in Chromium 151.0.7922.34 and Firefox 155.0;
+14/14 assertions met. [Review](../../reviews/FeatureReleaseExperiment.md),
+[results](result.json), [provenance](provenance.json).
+
+This is an authored synthetic host using real browser-native modules/import maps,
+not execution of the earlier FSD/single-spa examples or a production release system.
+The host API is fixed at 1. Reports R1/R2 support 1, R3 declares 2; Account A1 stays
+unchanged. Each new HTML document receives the current map. Published assets and
+activation bindings are separate in-memory controls in the test server.
+
+## Reproduce
+
+From this directory:
+
+```bash
+npm ci --ignore-scripts --cache /tmp/fep-npm-cache
+PLAYWRIGHT_BROWSERS_PATH=/tmp/fep-playwright-browsers node node_modules/playwright/cli.js install firefox
+PLAYWRIGHT_BROWSERS_PATH=/tmp/fep-playwright-browsers FEP_CHROMIUM_PATH=/path/to/chrome npm test
+```
+
+Playwright 1.63.0 is locked. Recorded runs used the same browser binaries identified
+by hashes in provenance.json, with an explicit Chromium executable override. Firefox
+required execution outside the workspace sandbox to access its temporary profile.
+No external network is used during cases. Loopback server/browser cleanup is automatic.
+Outputs default to `/tmp/fep-release-result.json` and an incomplete checkpoint at
+`/tmp/fep-release-checkpoint.json`; `FEP_RESULT_PATH` overrides the final destination.
+Any failed assertion produces nonzero exit. Receipts are not overwritten automatically.
+
+## Cases and limits
+
+| Case | Observed result in both browsers |
+| --- | --- |
+| X01 Publish R2 without changing binding | Fresh page still uses R1; no R2 request |
+| X02 Activate compatible R2 | Fresh page R2; old loaded and old lazy pages R1; Account A1 unchanged |
+| X03 Activate incompatible R3 | Host rejects mount, Account works; R3 module has already evaluated |
+| X04 Point binding to missing artifact | Reports error, Account navigation still usable |
+| X05 Roll binding back R2 → R1 | Fresh page R1; running page R2; explicit reload gets R1 |
+| X06 Retire R1 after activating R2 | Old loaded page retains R1; old lazy page fails; new page uses R2 |
+| X07 Fail shared startup module | Both navigation buttons remain disabled; feature loading never starts |
+
+Negative controls intentionally pass when the specified failure is observed. All
+responses disable HTTP caching, so this is not a CDN/cache invalidation test. Existing
+pages retain their document maps; dynamic map mutation/hot replacement is not tested.
+Only the host's deliberately tiny API-version contract is checked; module evaluation
+can already have side effects before that check. No backend writes, authentication,
+API migrations, atomic/concurrent map updates, accessibility audit or safe reload of
+unsaved work is modeled. The startup outage reflects this fixture's chosen dependency,
+not an assertion that every independently released frontend must fail that way.

research/experiments/feature-release/account-a1.js

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+export const version = 'A1';
+export const hostApi = 1;
+window.observed.evaluations.push(version);
+export function mount(node) { node.textContent = 'Account A1'; }

research/experiments/feature-release/experiment.mjs

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+import {chromium, firefox} from 'playwright';
+import {createServer} from 'node:http';
+import {once} from 'node:events';
+import {readFile,writeFile} from 'node:fs/promises';
+import {fileURLToPath} from 'node:url';
+import {createHash} from 'node:crypto';
+import assert from 'node:assert/strict';
+const dir=fileURLToPath(new URL('.',import.meta.url));
+const fileNames=['host.js','reports-r1.js','reports-r2.js','reports-r3.js','account-a1.js','shared.js'];
+const assets=new Map(await Promise.all(fileNames.map(async f=>['/'+f,await readFile(dir+f)])));
+let binding, published, sharedDown, requests;
+function reset(){binding={reports:'/reports-r1.js',account:'/account-a1.js',shared:'/shared.js'};published=new Set(['/host.js','/reports-r1.js','/account-a1.js','/shared.js']);sharedDown=false;requests=[];}
+reset();
+const server=createServer((req,res)=>{
+ const path=new URL(req.url,'http://localhost').pathname;
+ res.setHeader('Cache-Control','no-store');
+ if(path==='/'){
+ requests.push({path,status:200,binding:{...binding}});res.setHeader('Content-Type','text/html');
+ res.end(`<!doctype html><html lang="en"><title>Feature release probe</title><body><nav><button id="reports-nav" disabled>Reports</button><button id="account-nav" disabled>Account</button></nav><p id="status" role="status">starting</p><section id="reports"></section><section id="account"></section><script type="importmap">${JSON.stringify({imports:binding})}</script><script type="module" src="/host.js"></script></body></html>`);
+ }else if(path==='/shared.js'&&sharedDown){requests.push({path,status:503});res.writeHead(503,{'Content-Type':'text/plain'});res.end('synthetic startup outage');}
+ else if(published.has(path)&&assets.has(path)){requests.push({path,status:200});res.setHeader('Content-Type','application/javascript');res.end(assets.get(path));}
+ else{requests.push({path,status:404});res.writeHead(404,{'Content-Type':'text/plain'});res.end('artifact absent');}
+});
+server.listen(0,'127.0.0.1');await once(server,'listening');
+const url=`http://127.0.0.1:${server.address().port}`;
+const results=[];
+try{
+ for(const [engine,launcher]of [['chromium',chromium],['firefox',firefox]]){
+ const browser=await launcher.launch({headless:true,...(engine==='chromium'&&process.env.FEP_CHROMIUM_PATH?{executablePath:process.env.FEP_CHROMIUM_PATH}:{})});
+ try{
+ async function scenario(id,run){reset();const pages=[];const r={id,engine,browser:browser.version(),status:'pass'};
+ async function session(expected='ready'){const p=await browser.newPage();p.setDefaultTimeout(2500);pages.push(p);await p.goto(url);await p.locator('#status').filter({hasText:expected}).waitFor();return p;}
+ try{r.observation=await run(session);}catch(e){r.status='fail';r.error=e.message;}
+ r.sessions=await Promise.all(pages.map(p=>p.evaluate(()=>({text:document.body.innerText,observed:window.observed}))));r.requests=[...requests];results.push(r);for(const p of pages)await p.close();
+ await writeFile('/tmp/fep-release-checkpoint.json',JSON.stringify({status:'incomplete',results},null,2)+'\n');}
+ const reports=p=>p.evaluate(()=>window.loadReports());const account=p=>p.evaluate(()=>window.loadAccount());
+ await scenario('X01-publish-without-activation',async open=>{published.add('/reports-r2.js');const p=await open();assert.deepEqual(await reports(p),{ok:true,version:'R1'});assert(!requests.some(x=>x.path==='/reports-r2.js'));return {active:'R1',publishedButUnused:'R2'};});
+ await scenario('X02-compatible-activation-old-and-lazy',async open=>{
+ const loaded=await open();assert.equal((await reports(loaded)).version,'R1');const lazy=await open();published.add('/reports-r2.js');binding.reports='/reports-r2.js';const fresh=await open();
+ assert.equal((await reports(fresh)).version,'R2');assert.equal((await reports(loaded)).version,'R1');assert.equal((await reports(lazy)).version,'R1');for(const p of [loaded,lazy,fresh])assert.equal((await account(p)).version,'A1');
+ return {fresh:'R2',oldLoaded:'R1',oldLazy:'R1',account:'A1',hostUnchanged:true};});
+ await scenario('X03-incompatible-module',async open=>{published.add('/reports-r3.js');binding.reports='/reports-r3.js';const p=await open();assert.deepEqual(await reports(p),{ok:false,message:'incompatible host API'});assert.equal((await account(p)).version,'A1');const o=await p.evaluate(()=>window.observed);assert(o.evaluations.includes('R3'));assert(!o.mounts.some(x=>x.name==='reports'));return {incompatibleMountRejected:true,moduleAlreadyEvaluated:true,accountUsable:true};});
+ await scenario('X04-missing-artifact',async open=>{binding.reports='/missing.js';const p=await open();assert.equal((await reports(p)).ok,false);await p.locator('#account-nav').click();await p.locator('#account').filter({hasText:'Account A1'}).waitFor();assert(requests.some(x=>x.path==='/missing.js'&&x.status===404));return {localLoadFailure:true,navigationUsable:true};});
+ await scenario('X05-rollback-fresh-versus-running',async open=>{published.add('/reports-r2.js');binding.reports='/reports-r2.js';const old=await open();assert.equal((await reports(old)).version,'R2');binding.reports='/reports-r1.js';const fresh=await open();assert.equal((await reports(fresh)).version,'R1');assert.equal((await reports(old)).version,'R2');await old.reload();await old.locator('#status').filter({hasText:'ready'}).waitFor();assert.equal((await reports(old)).version,'R1');return {freshAfterRollback:'R1',runningBeforeReload:'R2',afterExplicitReload:'R1'};});
+ await scenario('X06-retired-old-artifact',async open=>{const loaded=await open();assert.equal((await reports(loaded)).version,'R1');const lazy=await open();published.add('/reports-r2.js');binding.reports='/reports-r2.js';published.delete('/reports-r1.js');assert.equal((await reports(loaded)).version,'R1');assert.equal((await reports(lazy)).ok,false);const fresh=await open();assert.equal((await reports(fresh)).version,'R2');return {oldLoadedStillWorks:true,oldLazyFails:true,newSession:'R2'};});
+ await scenario('X07-shared-startup-outage',async open=>{sharedDown=true;const p=await open('startup failed');assert.equal(await p.locator('#reports-nav').isDisabled(),true);assert.equal(await p.locator('#account-nav').isDisabled(),true);assert(requests.some(x=>x.path==='/shared.js'&&x.status===503));assert(!requests.some(x=>x.path==='/reports-r1.js'));return {bothNavigationActionsBlocked:true,featureLoadingNeverStarted:true};});
+ }finally{await browser.close();}
+ }
+}finally{await new Promise(resolve=>server.close(resolve));}
+const files={};for(const f of [...fileNames,'experiment.mjs','package.json','package-lock.json'])files[f]=createHash('sha256').update(await readFile(dir+f)).digest('hex');
+const output=process.env.FEP_RESULT_PATH||'/tmp/fep-release-result.json';const result={date:new Date().toISOString(),node:process.version,kind:'synthetic-native-es-module-browser-experiment',files,results,passed:results.filter(x=>x.status==='pass').length,total:results.length};await writeFile(output,JSON.stringify(result,null,2)+'\n');console.log(JSON.stringify({output,passed:result.passed,total:result.total,failures:results.filter(x=>x.status==='fail')},null,2));if(result.passed!==result.total)process.exitCode=1;

research/experiments/feature-release/host.js

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+const HOST_API = 1;
+window.observed = {mounts: [], errors: [], evaluations: [], hostApi: HOST_API};
+const report = document.getElementById('reports');
+const account = document.getElementById('account');
+async function load(name, target) {
+  try {
+    const feature = name === 'reports' ? await import('reports') : await import('account');
+    // Compatibility gate, not a security boundary: module evaluation already happened.
+    if (feature.hostApi !== HOST_API) throw new Error('incompatible host API');
+    feature.mount(target);
+    window.observed.mounts.push({name, version: feature.version});
+    return {ok: true, version: feature.version};
+  } catch (error) {
+    target.textContent = `${name} unavailable`;
+    window.observed.errors.push({name, message: error.message});
+    return {ok: false, message: error.message};
+  }
+}
+window.loadReports = () => load('reports', report);
+window.loadAccount = () => load('account', account);
+try {
+  await import('shared');
+  for (const button of document.querySelectorAll('button')) button.disabled = false;
+  document.getElementById('status').textContent = 'ready';
+} catch {
+  document.getElementById('status').textContent = 'startup failed';
+}
+document.getElementById('reports-nav').onclick = window.loadReports;
+document.getElementById('account-nav').onclick = window.loadAccount;

research/experiments/feature-release/package-lock.json

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+{
+  "name": "fep-feature-release",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "name": "fep-feature-release",
+      "dependencies": {
+        "playwright": "1.63.0"
+      }
+    },
+    "node_modules/playwright": {
+      "version": "1.63.0",
+      "resolved": "https://registry.npmjs.org/playwright/-/playwright-1.63.0.tgz",
+      "integrity": "sha512-+7ziBLidS4NaNCdt57SUDT+wYmmd5fmiQejUic/kb+YsYSCPyOOE9sebzMjNmQrsnNpDJqd4WHvV/8lfKfUDUg==",
+      "license": "Apache-2.0",
+      "dependencies": {
+        "playwright-core": "1.63.0"
+      },
+      "bin": {
+        "playwright": "cli.js"
+      },
+      "engines": {
+        "node": ">=20"
+      }
+    },
+    "node_modules/playwright-core": {
+      "version": "1.63.0",
+      "resolved": "https://registry.npmjs.org/playwright-core/-/playwright-core-1.63.0.tgz",
+      "integrity": "sha512-rYCsBF/M5HjUch52bbtVONEFjv6Xu8sm8h72dNlR5bzIE1fvC/bxgspzkjSfU+MweEMmPM8KJebG6nnyxo5mCg==",
+      "license": "Apache-2.0",
+      "bin": {
+        "playwright-core": "cli.js"
+      },
+      "engines": {
+        "node": ">=20"
+      }
+    }
+  }
+}

research/experiments/feature-release/package.json

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+{
+  "name": "fep-feature-release",
+  "private": true,
+  "type": "module",
+  "scripts": {"test": "node experiment.mjs"},
+  "dependencies": {"playwright": "1.63.0"}
+}

research/experiments/feature-release/provenance.json

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+{
+  "date": "2026-09-26",
+  "packages": {
+    "node_modules/playwright": {
+      "version": "1.63.0",
+      "resolved": "https://registry.npmjs.org/playwright/-/playwright-1.63.0.tgz",
+      "integrity": "sha512-+7ziBLidS4NaNCdt57SUDT+wYmmd5fmiQejUic/kb+YsYSCPyOOE9sebzMjNmQrsnNpDJqd4WHvV/8lfKfUDUg=="
+    },
+    "node_modules/playwright-core": {
+      "version": "1.63.0",
+      "resolved": "https://registry.npmjs.org/playwright-core/-/playwright-core-1.63.0.tgz",
+      "integrity": "sha512-rYCsBF/M5HjUch52bbtVONEFjv6Xu8sm8h72dNlR5bzIE1fvC/bxgspzkjSfU+MweEMmPM8KJebG6nnyxo5mCg=="
+    }
+  },
+  "chromium": {
+    "version": "151.0.7922.34",
+    "executable_sha256": "0b20b130e7edd9dd51873be867761295fe0cfad490c2b9a64f95bd3cfc08fa71",
+    "selection": "preinstalled Chromium build 1234, explicit executable override; not claimed to be Playwright 1.63 bundled revision"
+  },
+  "firefox": {
+    "playwright_build": "1543",
+    "executable_sha256": "062272ac4d851eade5b75db2dc7c14569d96cb3ca38f949337cdc1b74367e35b",
+    "version": "155.0"
+  },
+  "execution": "Local loopback server, native ES modules and import maps; synthetic host/artifacts; no production or single-spa deployment",
+  "http_cache": "All responses use Cache-Control: no-store; no service worker or CDN",
+  "activation": "Runner changes an in-memory binding used only in newly served documents; no client hot-rebinding or concurrent deployment protocol"
+}

research/experiments/feature-release/reports-r1.js

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+export const version = 'R1';
+export const hostApi = 1;
+window.observed.evaluations.push(version);
+export function mount(node) { node.textContent = 'Reports R1'; }

research/experiments/feature-release/reports-r2.js

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+export const version = 'R2';
+export const hostApi = 1;
+window.observed.evaluations.push(version);
+export function mount(node) { node.textContent = 'Reports R2'; }

research/experiments/feature-release/reports-r3.js

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+export const version = 'R3';
+export const hostApi = 2;
+window.observed.evaluations.push(version);
+export function mount(node) { node.textContent = 'Reports R3 incompatible'; }

research/experiments/feature-release/shared.js

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+export const sharedVersion = 'S1';