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Vibe codingHardvc-g349
Subject Ai code reviewLevel Senior~20 minCommon in Networking & APIs interviewsIndustries Software development, Telecom

Question

An AI wrote this TypeScript handler to decode incoming WebSocket frames in a Node server. Most messages work; some large or split messages come out mangled. Explain the framing bug(s), the trigger, and the fix.

ts
function onData(chunk: Buffer) {  const fin = (chunk[0] & 0x80) !== 0;  const opcode = chunk[0] & 0x0f;  const len = chunk[1] & 0x7f;          // payload length  const masked = (chunk[1] & 0x80) !== 0;  const maskStart = 2;  const payloadStart = maskStart + 4;  const payload = chunk.slice(payloadStart, payloadStart + len);  deliver(opcode, payload.toString());}
What a strong answer looks like

Treat the AI’s output as a draft to verify, not an answer to trust. Name the specific flaw and the input that triggers it, say how you’d catch it — tests, edge cases, reading critically — and how you’d re-prompt or decompose to get it right.

Learn the concepts
Describe your solution

Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.

Run or narrate your approach, then ask the coach.