refactor: convert app/scripts/lib/stream-utils.js to TypeScript

[Copilot]

[skip-e2e]
Converts app/scripts/lib/stream-utils.js to TypeScript as part of the ongoing TS migration effort, and removes its entry from files-to-convert.json.

Changes

• stream-utils.ts — renamed from .js with the following type additions:
  • StreamLike type capturing the internal stream properties accessed by isStreamWritable across implementations (node:stream, readable-stream v2/v3/v4, @metamask/object-multiplex)
  • setupMultiplex: parameter typed as Duplex, return typed as ObjectMultiplex
  • isStreamWritable: parameter typed as StreamLike, return typed as boolean; pipeline error callback typed as Error | null
  • pipeline import uses // @ts-expect-error (consistent with provider-stream.ts, phishing-stream.ts, cookie-handler-stream.ts)
  • Inner /** */ docblock inside isStreamWritable converted to /* */ to satisfy jsdoc/check-indentation

type StreamLike = {
  writable?: boolean;
  destroyed?: boolean;
  _writableState?: { ended: boolean };
};

export function setupMultiplex(connectionStream: Duplex): ObjectMultiplex { ... }
export function isStreamWritable(stream: StreamLike): boolean { ... }

• files-to-convert.json — removed "app/scripts/lib/stream-utils.js" entry

---

Note

Low Risk
Low risk TS migration change that primarily adds typings and adjusts imports/comments; runtime behavior should be unchanged aside from slightly stricter stream type expectations at compile time.

Overview
Converts app/scripts/lib/stream-utils from JS to TS, adding explicit types for setupMultiplex (now Duplex -> ObjectMultiplex) and isStreamWritable (now accepts a StreamLike shape used across multiple stream implementations).

Adjusts the readable-stream import to include Duplex with a @ts-expect-error and tightens the pipeline error callback type, and removes stream-utils.js from the TS migration dashboard list.

^{Reviewed by Cursor Bugbot for commit 0c2a1f1. Bugbot is set up for automated code reviews on this repo. Configure here.}

[metamaskbotv2]

Builds ready [b438d0c]

• builds: chrome, firefox
• builds (beta): chrome, firefox
• builds (flask): chrome, firefox
• builds (test): chrome, firefox
• builds (test-flask): chrome, firefox
• webpack builds: chrome, firefox
• webpack builds (beta): chrome, firefox
• webpack builds (flask): chrome, firefox
• webpack builds (test): chrome, firefox
• webpack builds (test-flask): chrome, firefox
• bundle size: Bundle Size Stats
• interaction-benchmark: Interaction Stats
• storybook: Storybook
• typescript migration: Dashboard
• all artifacts
• bundle viz:

  • background: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11
  • common: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21
  • ui: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20
  • content-script: 0
  • offscreen: 0

⚡ Performance Benchmarks (Total: 🟢 6 pass · 🟡 12 warn · 🔴 0 fail)

Baseline (latest main): f34f804 | Date: 9/10/58222 | Pipeline: 23941922795 | Baseline logs

Interaction Benchmarks

Benchmark	chrome-browserify
loadNewAccount	🟡 [Show logs]
confirmTx	🟡 [Show logs]
bridgeUserActions	🟡 [Show logs]

📈 Results compared to the previous 5 runs on main

• ↑ bridgeUserActions/bridge_load_page: +13%

🌐 Core Web Vitals — 🟢 good · 🟡 needs improvement · 🔴 poor (web.dev thresholds)

• 🟡 loadNewAccount/FCP: p75 2.5s
• 🟡 confirmTx/FCP: p75 2.5s
• 🟡 bridgeUserActions/FCP: p75 2.5s

Startup Benchmarks

Benchmark	chrome-browserify	chrome-webpack	firefox-browserify	firefox-webpack
startupStandardHome	🟢 [Show logs]	🟢 [Show logs]	🟢 [Show logs]	🟢 [Show logs]
startupPowerUserHome	🟡 [Show logs]	🟡 [Show logs]	🟡 [Show logs]	🟡 [Show logs]

📈 Results compared to the previous 5 runs on main

• ↓ startupStandardHome/uiStartup: -10%
• ↓ startupStandardHome/load: -12%
• ↓ startupStandardHome/domContentLoaded: -13%
• ↑ startupStandardHome/domInteractive: +17%
• ↑ startupStandardHome/backgroundConnect: +13%
• ↓ startupStandardHome/initialActions: -38%
• ↓ startupStandardHome/loadScripts: -16%
• ↓ startupStandardHome/numNetworkReqs: -11%
• ↓ startupPowerUserHome/uiStartup: -12%
• ↑ startupPowerUserHome/backgroundConnect: +120%
• ↑ startupPowerUserHome/numNetworkReqs: +14%
• ↓ startupStandardHome/uiStartup: -13%
• ↓ startupStandardHome/load: -13%
• ↓ startupStandardHome/domContentLoaded: -12%
• ↓ startupStandardHome/backgroundConnect: -35%
• ↓ startupStandardHome/firstReactRender: -24%
• ↓ startupStandardHome/loadScripts: -12%
• ↓ startupStandardHome/numNetworkReqs: -29%
• ↓ startupPowerUserHome/domInteractive: -18%
• ↑ startupPowerUserHome/numNetworkReqs: +49%
• ↓ startupStandardHome/domInteractive: -59%
• ↓ startupStandardHome/initialActions: -38%
• ↓ startupStandardHome/numNetworkReqs: -18%
• ↑ startupPowerUserHome/domInteractive: +14%
• ↓ startupPowerUserHome/backgroundConnect: -21%
• ↑ startupPowerUserHome/setupStore: +17%
• ↓ startupStandardHome/domInteractive: -53%
• ↓ startupStandardHome/backgroundConnect: -17%
• ↓ startupStandardHome/initialActions: -44%
• ↓ startupStandardHome/setupStore: -63%
• ↓ startupPowerUserHome/domInteractive: -16%
• ↓ startupPowerUserHome/backgroundConnect: -25%
• ↓ startupPowerUserHome/firstReactRender: -11%
• ↓ startupPowerUserHome/setupStore: -24%

🌐 Core Web Vitals — 🟢 good · 🟡 needs improvement · 🔴 poor (web.dev thresholds)

• 🔴 startupPowerUserHome/INP: p75 624ms
• 🔴 startupPowerUserHome/INP: p75 688ms
• 🟡 startupPowerUserHome/LCP: p75 3.8s
• 🟡 startupPowerUserHome/LCP: p75 3.6s

User Journey Benchmarks

Benchmark	chrome-browserify
onboardingImportWallet	🟢 [Show logs]
onboardingNewWallet	🟢 [Show logs]
assetDetails	🟡 [Show logs]
solanaAssetDetails	🟡 [Show logs]
importSrpHome	🟡 [Show logs]
sendTransactions	🟡 [Show logs]
swap	🟡 [Show logs]

📈 Results compared to the previous 5 runs on main

• ↓ onboardingImportWallet/srpButtonToSrpForm: -11%
• ↓ onboardingImportWallet/metricsToWalletReadyScreen: -35%
• ↓ onboardingImportWallet/doneButtonToHomeScreen: -75%
• ↑ onboardingImportWallet/openAccountMenuToAccountListLoaded: +32%
• ↓ onboardingImportWallet/total: -39%
• ↑ onboardingNewWallet/srpButtonToPwForm: +14%
• ↓ onboardingNewWallet/skipBackupToMetricsScreen: -17%
• ↓ onboardingNewWallet/agreeButtonToOnboardingSuccess: -18%
• ↓ onboardingNewWallet/doneButtonToAssetList: -35%
• ↓ onboardingNewWallet/total: -29%
• ↓ assetDetails/assetClickToPriceChart: -64%
• ↓ assetDetails/total: -64%
• ↓ solanaAssetDetails/assetClickToPriceChart: -54%
• ↓ solanaAssetDetails/total: -54%
• ↑ importSrpHome/loginToHomeScreen: +11%
• ↓ importSrpHome/openAccountMenuAfterLogin: -68%
• ↓ importSrpHome/homeAfterImportWithNewWallet: -37%
• ↓ importSrpHome/total: -32%
• ↑ sendTransactions/openSendPageFromHome: +114%
• ↓ swap/openSwapPageFromHome: -86%
• ↑ swap/fetchAndDisplaySwapQuotes: +31%
• ↑ swap/total: +13%

🌐 Core Web Vitals — 🟢 good · 🟡 needs improvement · 🔴 poor (web.dev thresholds)

• 🟡 assetDetails/INP: p75 216ms
• 🟡 assetDetails/FCP: p75 2.4s
• 🟡 solanaAssetDetails/FCP: p75 2.4s
• 🟡 importSrpHome/INP: p75 216ms
• 🟡 importSrpHome/FCP: p75 2.5s
• 🟡 sendTransactions/INP: p75 216ms
• 🟡 sendTransactions/FCP: p75 2.4s
• 🟡 swap/FCP: p75 2.4s

🌐 Dapp Page Load Benchmarks

Current Commit: b438d0c | Date: 4/3/2026

📄 Localhost MetaMask Test Dapp

Samples: 100

Summary

• pageLoadTime-> current mean value: 984ms (±40ms) 🟢 | historical mean value: 1.03s ⬇️ (historical data)
• domContentLoaded-> current mean value: 691ms (±37ms) 🟢 | historical mean value: 723ms ⬇️ (historical data)
• firstContentfulPaint-> current mean value: 81ms (±9ms) 🟢 | historical mean value: 86ms ⬇️ (historical data)

📈 Detailed Results

Metric	Mean	Std Dev	Min	Max	P95	P99
pageLoadTime	984ms	40ms	954ms	1.28s	1.02s	1.28s
domContentLoaded	691ms	37ms	669ms	964ms	718ms	964ms
firstPaint	81ms	9ms	68ms	152ms	92ms	152ms
firstContentfulPaint	81ms	9ms	68ms	152ms	92ms	152ms
largestContentfulPaint	0ms	0ms	0ms	0ms	0ms	0ms

Bundle size diffs

• background: 58 Bytes (0%)
• ui: 5 Bytes (0%)
• common: 20 Bytes (0%)

[github-actions]

CLA Signature Action: All authors have signed the CLA. You may need to manually re-run the blocking PR check if it doesn't pass in a few minutes.

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
92.9% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[metamaskbotv2]

Builds ready [0c2a1f1]

• builds: chrome, firefox
• builds (beta): chrome, firefox
• builds (flask): chrome, firefox
• builds (test): chrome, firefox
• builds (test-flask): chrome, firefox
• webpack builds: chrome, firefox
• webpack builds (beta): chrome, firefox
• webpack builds (flask): chrome, firefox
• webpack builds (test): chrome, firefox
• webpack builds (test-flask): chrome, firefox
• bundle size: Bundle Size Stats
• interaction-benchmark: Interaction Stats
• storybook: Storybook
• typescript migration: Dashboard
• all artifacts
• bundle viz:

  • background: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11
  • common: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21
  • ui: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20
  • content-script: 0
  • offscreen: 0

⚡ Performance Benchmarks (Total: 🟢 6 pass · 🟡 12 warn · 🔴 0 fail)

Baseline (latest main): f34f804 | Date: 9/10/58222 | Pipeline: 24008405906 | Baseline logs

Interaction Benchmarks

Benchmark	chrome-browserify
loadNewAccount	🟡 [Show logs]
confirmTx	🟡 [Show logs]
bridgeUserActions	🟡 [Show logs]

📈 Results compared to the previous 5 runs on main

• ↓ loadNewAccount/load_new_account: -18%
• ↓ loadNewAccount/total: -18%
• ↑ bridgeUserActions/bridge_load_asset_picker: +15%

🌐 Core Web Vitals — 🟢 good · 🟡 needs improvement · 🔴 poor (web.dev thresholds)

• 🟡 loadNewAccount/FCP: p75 2.5s
• 🟡 confirmTx/FCP: p75 2.5s
• 🟡 bridgeUserActions/FCP: p75 2.5s

Startup Benchmarks

Benchmark	chrome-browserify	chrome-webpack	firefox-browserify	firefox-webpack
startupStandardHome	🟢 [Show logs]	🟢 [Show logs]	🟢 [Show logs]	🟢 [Show logs]
startupPowerUserHome	🟡 [Show logs]	🟡 [Show logs]	🟡 [Show logs]	🟡 [Show logs]

📈 Results compared to the previous 5 runs on main

• ↓ startupStandardHome/uiStartup: -15%
• ↓ startupStandardHome/load: -17%
• ↓ startupStandardHome/domContentLoaded: -19%
• ↑ startupStandardHome/initialActions: +25%
• ↓ startupStandardHome/loadScripts: -22%
• ↓ startupPowerUserHome/uiStartup: -16%
• ↑ startupPowerUserHome/backgroundConnect: +88%
• ↑ startupPowerUserHome/firstReactRender: +11%
• ↑ startupPowerUserHome/setupStore: +39%
• ↑ startupPowerUserHome/numNetworkReqs: +13%
• ↓ startupStandardHome/uiStartup: -12%
• ↓ startupStandardHome/load: -12%
• ↓ startupStandardHome/domContentLoaded: -11%
• ↓ startupStandardHome/backgroundConnect: -34%
• ↓ startupStandardHome/firstReactRender: -24%
• ↓ startupStandardHome/loadScripts: -11%
• ↓ startupStandardHome/numNetworkReqs: -29%
• ↓ startupPowerUserHome/domInteractive: -24%
• ↓ startupPowerUserHome/firstPaint: -11%
• ↓ startupStandardHome/domInteractive: -56%
• ↑ startupStandardHome/initialActions: +25%
• ↓ startupStandardHome/numNetworkReqs: -18%
• ↓ startupPowerUserHome/uiStartup: -11%
• ↓ startupPowerUserHome/backgroundConnect: -30%
• ↓ startupStandardHome/domInteractive: -25%
• ↑ startupStandardHome/initialActions: +11%
• ↓ startupStandardHome/setupStore: -54%
• ↓ startupPowerUserHome/domInteractive: -13%
• ↓ startupPowerUserHome/backgroundConnect: -29%
• ↓ startupPowerUserHome/firstReactRender: -11%
• ↓ startupPowerUserHome/numNetworkReqs: -13%

🌐 Core Web Vitals — 🟢 good · 🟡 needs improvement · 🔴 poor (web.dev thresholds)

• 🔴 startupPowerUserHome/INP: p75 760ms
• 🔴 startupPowerUserHome/INP: p75 592ms
• 🟡 startupPowerUserHome/LCP: p75 3.4s
• 🟡 startupPowerUserHome/INP: p75 232ms
• 🟡 startupPowerUserHome/LCP: p75 3.6s

User Journey Benchmarks

Benchmark	chrome-browserify
onboardingImportWallet	🟢 [Show logs]
onboardingNewWallet	🟢 [Show logs]
assetDetails	🟡 [Show logs]
solanaAssetDetails	🟡 [Show logs]
importSrpHome	🟡 [Show logs]
sendTransactions	🟡 [Show logs]
swap	🟡 [Show logs]

📈 Results compared to the previous 5 runs on main

• ↑ onboardingImportWallet/pwFormToMetricsScreen: +22%
• ↓ onboardingImportWallet/doneButtonToHomeScreen: -75%
• ↑ onboardingImportWallet/openAccountMenuToAccountListLoaded: +42%
• ↓ onboardingImportWallet/total: -41%
• ↑ onboardingNewWallet/createPwToRecoveryScreen: +12%
• ↓ onboardingNewWallet/skipBackupToMetricsScreen: -15%
• ↑ onboardingNewWallet/agreeButtonToOnboardingSuccess: +45%
• ↓ onboardingNewWallet/doneButtonToAssetList: -32%
• ↓ onboardingNewWallet/total: -27%
• ↓ assetDetails/assetClickToPriceChart: -65%
• ↓ assetDetails/total: -65%
• ↓ solanaAssetDetails/assetClickToPriceChart: -59%
• ↓ solanaAssetDetails/total: -59%
• ↑ importSrpHome/loginToHomeScreen: +27%
• ↓ importSrpHome/openAccountMenuAfterLogin: -67%
• ↓ importSrpHome/homeAfterImportWithNewWallet: -29%
• ↓ importSrpHome/total: -22%
• ↑ sendTransactions/openSendPageFromHome: +168%
• ↑ sendTransactions/total: +13%
• ↓ swap/openSwapPageFromHome: -85%
• ↑ swap/fetchAndDisplaySwapQuotes: +31%
• ↑ swap/total: +14%

🌐 Core Web Vitals — 🟢 good · 🟡 needs improvement · 🔴 poor (web.dev thresholds)

• 🟡 assetDetails/INP: p75 232ms
• 🟡 assetDetails/FCP: p75 2.6s
• 🟡 solanaAssetDetails/FCP: p75 2.7s
• 🟡 importSrpHome/INP: p75 264ms
• 🟡 importSrpHome/FCP: p75 2.9s
• 🟡 sendTransactions/INP: p75 216ms
• 🟡 sendTransactions/FCP: p75 2.5s
• 🟡 swap/FCP: p75 2.5s

🌐 Dapp Page Load Benchmarks

Current Commit: 0c2a1f1 | Date: 4/5/2026

📄 Localhost MetaMask Test Dapp

Samples: 100

Summary

• pageLoadTime-> current mean value: 1.04s (±147ms) 🟡 | historical mean value: 1.04s ⬆️ (historical data)
• domContentLoaded-> current mean value: 732ms (±146ms) 🟢 | historical mean value: 728ms ⬆️ (historical data)
• firstContentfulPaint-> current mean value: 95ms (±125ms) 🟢 | historical mean value: 86ms ⬆️ (historical data)

📈 Detailed Results

Metric	Mean	Std Dev	Min	Max	P95	P99
pageLoadTime	1.04s	147ms	996ms	2.48s	1.08s	2.48s
domContentLoaded	732ms	146ms	696ms	2.16s	769ms	2.16s
firstPaint	95ms	125ms	64ms	1.34s	100ms	1.34s
firstContentfulPaint	95ms	125ms	64ms	1.34s	100ms	1.34s
largestContentfulPaint	0ms	0ms	0ms	0ms	0ms	0ms

Bundle size diffs [🚨 Warning! Bundle size has increased!]

• background: 58 Bytes (0%)
• ui: 10.28 KiB (0.12%)
• common: 2.42 KiB (0.02%)