Cancel disconnected offer analysis and stop remaining provider calls

server/request-lifetime.mjs

@@ -0,0 +1,9 @@
+/** Request completion is normal; premature response closure cancels dependent work. */
+export function requestLifetime(req, res) {
+  const controller = new AbortController();
+  const abort = () => controller.abort();
+  const closed = () => {if (!res.writableFinished) abort();};
+  req.once('aborted',abort);res.once('close',closed);
+  if(req.aborted || res.destroyed) abort();
+  return {signal:controller.signal,dispose(){req.off('aborted',abort);res.off('close',closed);}};
+}