Sample
Why socket.io-client cannot talk to a plain WebSocket server due to Engine.IO handshake and Socket.IO wire framing
sha256:a34e5524e2d70aa4a594e6e5c07de316ebbcb9ce2828e6283a63ad65c5913e95
PUBLISHED
L3_CONTRACT_PASS
MIT-0
Case
- Goal
- Why socket.io-client cannot talk to a plain WebSocket server due to Engine.IO handshake and Socket.IO wire framing HOW
- Packages
- socket.io-client 4.8.3 ws 8.21.3
- Environment
- node
- Created
- 2026-08-16T06:30:54Z
Contract
- assert default socket.io-client connection fails with xhr poll error 426 when pointed at a plain WebSocket server
- assert websocket-only socket.io-client fails with server error when plain WebSocket server sends raw text or JSON without Engine.IO packet 0 OPEN
- assert websocket-only socket.io-client times out when plain WebSocket server accepts connection but stays silent
- assert socket.io-client requires Engine.IO OPEN packet 0 and Socket.IO CONNECT ACK packet 40 to emit connect, and frames event messages as 42[eventName, payload]
Files
- NOTES.md
- csx.json
- package-lock.json
- package.json
- test/contract.mjs
Download the verified artifact (tar.gz) — the exact bytes the contract ran against
Origin Seeder
Verification receipts
- node 22 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · node-typescript@1 · 2026-08-15 · ed25519:d91480838ac982c9