fix(connect): clean up leaked onConnect/WebUSB/BroadcastChannel listeners

[mroz22]

Summary

Three isolated listener / subscription leak fixes, split out of the broader audit in #27978 so they can be reviewed independently. Each touches a single file in a distinct package and adds the missing cleanup.

Fixes

• @trezor/connect-common — ServiceWorkerWindowChannel
connect() added a chrome.runtime.onConnect listener via an inline closure that was never removed. onConnect is a global Chrome event (unlike port.onMessage, which is port-scoped), so the leaked closure survived the whole extension lifetime and re-connect() stacked more. Now the listener is stored on the instance, registration is guarded against duplicates, and disconnect() removes it.

• @trezor/react-native-usb — WebUSB
set onconnect / set ondisconnect called onDeviceConnected/Disconnect() without storing the returned EventSubscription, so reassigning a handler leaked the native Android/iOS listener and assigning null registered a broken callback instead of removing. Setters now .remove() the previous subscription and accept null to clear.

• @trezor/connect-explorer — trezorConnectActions.init()
  Deeplink mode created a new BroadcastChannel('trezor_connect_callback') on every init() without closing the previous one. BroadcastChannel stays registered internally until close(), so repeated init stacked channels that all replied to every callback URL. Now the previous channel is closed before a new one is created.

Why split out

Three single-file, single-concern fixes in packages no other PR in the leak-audit stream touches. Each is trivially reviewable and independently revertible.

Related PRs (listener-leak audit stream)

• fix: audit and patch event listener leaks across transport/connect/desktop packages #27978 — fix: audit and patch event listener leaks across transport/connect/desktop packages (origin of these commits)
• fix(suite-desktop): clean up accumulated Electron listeners on re-init #28241 — fix(suite-desktop): clean up accumulated Electron listeners on re-init (sibling split-out: the two desktop fixes)
• feat(utils): introduce listener disposer helper for Connect/transport sites #27982 — feat(utils): introduce listener disposer helper for Connect/transport sites
• This PR cherry-picks the three isolated single-file fixes out of fix: audit and patch event listener leaks across transport/connect/desktop packages #27978 for independent review.

Test plan

• lint:js clean on all three changed files
• CI type-check + unit (full monorepo build)

🤖 Generated with Claude Code

🌐 Preview deployments

🌐 Suite Web preview: https://dev.suite.sldev.cz/suite-web/mroz22/isolated-listener-leaks/web/

🔍 Currents Test Results

🔍 Suite web test results: View in Currents

🔒 Quarantined E2E Tests

Trezor Suite (web) — 10 test(s)

Test	Type
Account metadata > dropbox provider	🤖 auto
Export transactions > Go to account and try to export all possible variants (pdf, csv, json)	🤖 auto
Passphrase with cardano > verify cardano address behind passphrase	🤖 auto
Cardano > Basic cardano walkthrough	🤖 auto
Public Keys > Check ada XPUB	🤖 auto
Account types suite > Add-account-types-non-BTC-coins	🤖 auto
Quarantine test: "Onboarding - create wallet,Success (basic)"	🙋 manual
Quarantine test: "Database migration,Db migration between: release/22.5/web => develop/web"	🙋 manual
Quarantine test: "Multiple sessions,Session overtaken by another"	🙋 manual
Quarantine test: "Recovery T2T1 - dry run,Recovery after partial recovery"	🙋 manual

Updated: 2026-06-01T15:08:09.674Z • 10 test(s) total

[mroz22]

CI Maintenance — 2026-06-02

All CI checks green. No reviews detected.

Actions taken this session:

• Copilot review requested

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Generated by Claude Code

[Copilot]

Pull request overview

Three small, independently revertible listener/subscription cleanup fixes split out of the broader leak audit in #27978. Each adds the missing teardown for a long-lived listener so repeated init()/connect() no longer stack handlers.

Changes:

• ServiceWorkerWindowChannel.connect() stores the chrome.runtime.onConnect callback, guards against duplicate registration, and removes it in disconnect().
• WebUSB.onconnect/ondisconnect setters now store the returned EventSubscription, .remove() the previous one on overwrite, and accept null to clear.
• trezorConnectActions.init() closes the previous deeplink BroadcastChannel before creating a new one.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
packages/connect-common/src/messageChannel/serviceworker-window.ts	Track onConnect listener as an instance field; guard duplicate registration; remove in disconnect().
packages/react-native-usb/src/index.ts	Store and dispose EventSubscription returned by onDeviceConnected/onDeviceDisconnect; accept null to clear.
packages/connect-explorer/src/actions/trezorConnectActions.ts	Close the previous module-scoped BroadcastChannel before creating a new one on re-init.

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