diff --git a/apps/server/src/routes/qr-reader.ts b/apps/server/src/routes/qr-reader.ts
index 71985a7..b09665c 100644
--- a/apps/server/src/routes/qr-reader.ts
+++ b/apps/server/src/routes/qr-reader.ts
@@ -44,8 +44,14 @@ export async function qrReaderRoutes(
 
   // No auth: the reader is a machine on the isolated device subnet and offers no
   // auth on its side. Public route, like the Dingtian input push.
-  const handler = async (req: { query: ReaderQuery }) => {
+  const handler = async (req: { query: ReaderQuery }, reply: import("fastify").FastifyReply) => {
     const q = req.query;
+    // The reader sends `Connection: keep-alive` but only ACTS on our verdict (beep,
+    // drive output) once the socket CLOSES — every vendor demo replies
+    // `Connection: close` and shuts the socket. Without it the reader waits out a
+    // ~10 s keep-alive timeout before beeping. So force-close the connection.
+    // See wiki/sources/qrcode-sdk.md, entities/gee-qr-er80.md.
+    reply.header("connection", "close");
     const cardid = (q.cardid ?? "").trim();
     const mjihao = q.mjihao != null ? Number(q.mjihao) : 0;
     const serial = (q.cjihao ?? "").trim();
diff --git a/wiki/entities/gee-qr-er80.md b/wiki/entities/gee-qr-er80.md
index 20fb5f3..dedb657 100644
--- a/wiki/entities/gee-qr-er80.md
+++ b/wiki/entities/gee-qr-er80.md
@@ -111,3 +111,12 @@ enter its serial here.
   `status:1` 2-beep when the QR matches a permit/open session.
 - `output` is replied as `0` (Access). Confirm on hardware whether the reader needs `1`/`2` (WG26/34)
   to drive its access line, vs. `0`.
+
+## ⚠️ Reply MUST set `Connection: close` (verified on hardware)
+
+The reader sends `Connection: keep-alive` but **only acts on the verdict (beep/output) once the TCP
+socket CLOSES**. Fastify's default keeps the connection alive → the reader waits out a **~10 s
+keep-alive timeout before beeping**, even though the server replied in ~15 ms. Every vendor demo
+replies **`Connection: close`** and shuts the socket. Fix: the endpoint sets
+`reply.header("connection","close")`. Symptom if regressed: correct accept/reject but a ~10 s lag
+before the beep. (The request arrives fast; the delay is entirely the reader waiting for close.)
diff --git a/wiki/log.md b/wiki/log.md
index ca1b2f2..5869505 100644
--- a/wiki/log.md
+++ b/wiki/log.md
@@ -691,3 +691,12 @@ guarantee. Recorded in [[dingtian-relay]] (new Hardening section).
   [[dingtian-relay]] connected. NOT for production. Registered in the catalog.
 - To get a live accept: assign Stub barrier to the reader's lane + a permit whose QR = the scanned
   code → status:1 (2-beep) + logged pulseOpen.
+
+## [2026-06-16] fix | QR reader 10s beep delay — reply must Connection: close
+- Live accept worked (status:1, pulseOpen, 2 beeps) but the beep came ~10 s LATE. Server responded
+  in 14.7 ms; user confirmed request is fast, only the beep lags → delay is the READER, not us.
+- Cause: reader sends `Connection: keep-alive` but only ACTS on the verdict once the socket CLOSES;
+  Fastify kept it alive → reader waited out a ~10 s keep-alive timeout. Every vendor demo replies
+  `Connection: close` + shuts the socket.
+- Fix: endpoint sets `reply.header("connection","close")`. Verified the header is now sent.
+- Updated [[gee-qr-er80]] (⚠️ Connection: close requirement).