fix(events): use the WebSocket global and drop the ws dependency

[georgeglarson]

HUMAN:

Human verified, Screenshot attached.

---

AGENT:

Ported from OpenHands/typescript-client#370 (closed unmerged when that repo was archived and the client moved here; the moved files are byte-identical to the pre-fix versions, so the bug crossed repos untouched). Verified end-to-end from clients/typescript:

• Reproduced the issue on main first: npm ci && npm run build, then the repro from the linked issue — onError receives WebSocket implementation not available on Node 22.22.2 despite globalThis.WebSocket existing.
• Same repro on this branch: the error is gone; the client reads the global and attempts the connection.
• npx jest src/__tests__/package-import.test.ts → 8 passed, including new cases asserting each client opens the exact expected URL against a fake globalThis.WebSocket.
• npm test → 311 passed, 18 suites. npm run lint → 0 errors (and two fewer pre-existing any warnings in these files). npm run format:check → clean. npm run build → clean.

Why

The package is emitted as ESM, and Node 22 provides a standards-compatible globalThis.WebSocket. The conversation and bash event clients only checked window.WebSocket, then attempted require('ws') — which is unavailable in ESM — so starting either client in a Node ESM process reported WebSocket implementation not available even though the global exists. Full repro in the linked issue.

Summary

• Read globalThis.WebSocket directly in both event clients and drop the ws dependency (every supported runtime supplies the global: browsers, and Node.js since 22.4).
• Keep the "no implementation" condition deferred to connect() time and surfaced via the existing onError callback, so importing the package barrel still never throws.
• Rewrite the package-import tests to delete the global for real instead of mocking ws, and add coverage pinning the URL each client opens.

Issue Number

Fixes #4846.

How to Test

cd clients/typescript
npm ci
npm run build
node --input-type=module -e "const {WebSocketCallbackClient}=await import('./dist/events/websocket-client.js'); const client=new WebSocketCallbackClient({host:'http://127.0.0.1:9',conversationId:'test',callback:()=>{},onError:(e)=>console.error('ONERROR:',e.message)}); client.start(); client.stop()"

On main this prints ONERROR: ... WebSocket implementation not available; on this branch it does not. Then npm test and npx jest src/__tests__/package-import.test.ts.

Video/Screenshots

Design Doc

N/A — small runtime-detection fix.

Type

• Bug fix
• Feature
• Refactor
• Breaking change
• Docs / chore

Notes

The same change was previously reviewed as OpenHands/typescript-client#370 and went unmerged only because that repository was archived on 2026-08-30 when the client moved into this repo (OpenHands/typescript-client#371). Consumers on Node < 22.4 would lose the ws fallback, but the package already requires Node 22-era tooling throughout its CI and the global has been unflagged since Node 22.4.

[all-hands-bot]

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