When implementing HTTP/SSE adapters or transforming network responses/streams, enforce three rules: (1) preserve required response headers/trace metadata while normalizing body-related headers, (2) respect protocol framing so streamed events can’t merge, and (3) prevent hanging outbound calls with timeouts.

Apply this as a checklist:

Example patterns:

// 1) HTTP response transformation: preserve trace/version headers
function buildTransformedResponse(upstream: Response, data: any) {
  const newHeaders = new Headers(upstream.headers);
  // normalize payload headers for the transformed body
  newHeaders.set("Content-Type", "application/json");
  newHeaders.delete("Content-Length");
  return new Response(JSON.stringify(data), {
    status: upstream.status,
    headers: newHeaders,
  });
}

// 2) SSE framing: always end events with a delimiter
function enqueueSseEvent(controller: TransformStreamDefaultController, prefix: string, payload: string) {
  controller.enqueue(new TextEncoder().encode(`${prefix}${payload}\n\n`));
}

// 3) Outbound request timeout
async function fetchWithTimeout(url: string, init: RequestInit = {}, timeoutMs = 7000) {
  const ac = new AbortController();
  const t = setTimeout(() => ac.abort(), timeoutMs);
  try {
    return await fetch(url, { ...init, signal: ac.signal });
  } finally {
    clearTimeout(t);
  }
}

Teams should require these checks in code review for any networking code that adapts/streams/transforms data.