diff --git a/services/dingtalk-login/server.mjs b/services/dingtalk-login/server.mjs
index 6932eb5..fde437c 100644
--- a/services/dingtalk-login/server.mjs
+++ b/services/dingtalk-login/server.mjs
@@ -27,20 +27,25 @@ function redacted(s) {
 }
 
 function scheduleCleanup(s) {
-  setTimeout(() => { closeSession(s.id); }, Math.max(0, s.expiresAt - Date.now())).unref?.();
+  if (s.cleanupTimer) clearTimeout(s.cleanupTimer);
+  s.cleanupTimer = setTimeout(() => { void closeSession(s.id); }, Math.max(0, s.expiresAt - Date.now()));
+  s.cleanupTimer.unref?.();
 }
 
-function closeSession(id) {
+async function closeSession(id) {
   const s = sessions.get(id);
   if (!s) return;
   s.state = "closed";
   sessions.delete(id);
-  s.context?.close().catch(() => {});
+  if (s.cleanupTimer) clearTimeout(s.cleanupTimer);
+  if (s.regrabTimer) clearInterval(s.regrabTimer);
+  const context = s.context;
+  s.context = null;
+  if (context) await context.close().catch(() => {});
 }
 
-function evictOld() {
-  const live = [...sessions.values()].sort((a, b) => a.createdAt - b.createdAt);
-  while (live.length > 3) closeSession(live.shift().id);
+async function closeAllSessions() {
+  await Promise.all([...sessions.keys()].map((id) => closeSession(id)));
 }
 
 // ---------- capture ----------
@@ -53,11 +58,11 @@ function loadCapture() {
   } catch { return null; }
 }
 
-function writeCapture(headers) {
+function writeCapture(headers, space) {
   const payload = {
     capturedAt: new Date().toISOString(),
     method: "GET",
-    url: `https://alidocs.dingtalk.com/box/api/v2/dentry/list?dentryUuid=${VERIFY_SPACE}`,
+    url: `https://alidocs.dingtalk.com/box/api/v2/dentry/list?dentryUuid=${space}`,
     headers,
   };
   // The scanner reads this file through a single-file bind mount: replacing
@@ -161,9 +166,12 @@ async function startSession(id, space) {
 
   let capturedHeaders = null;
   const finish = async (headers) => {
-    const probe = await boxApi(headers, `/box/api/v2/dentry/list?dentryUuid=${VERIFY_SPACE}&pageSize=1&orderType=SORT_KEY&sortType=desc&listDentrySource=2&withParentAncestors=true`);
+    // Validate the space the operator actually opened. Validating against an
+    // unrelated default space rejects perfectly good logins when that account
+    // has no access to the old/default knowledge base.
+    const probe = await boxApi(headers, `/box/api/v2/dentry/list?dentryUuid=${encodeURIComponent(space)}&pageSize=1&orderType=SORT_KEY&sortType=desc&listDentrySource=2&withParentAncestors=true`);
     if (probe.status === 200 && probe.body && probe.body.data && probe.body.data.spaceProfile) {
-      writeCapture(headers);
+      writeCapture(headers, space);
       s.state = "success"; s.error = null;
     } else {
       s.state = "failed"; s.error = "capture_validation_failed";
@@ -172,25 +180,30 @@ async function startSession(id, space) {
     scheduleCleanup(s);
   };
 
-  const captureRequest = async (request) => {
-    const url = request.url();
-    if (!url.includes("dingtalk.com")) return;
-    // Playwright request.headers() intentionally omits security-related
-    // headers on some Chromium builds, notably Cookie. allHeaders() is the
-    // complete API and is required for the capture consumed by the scanner.
+  const captureResponse = async (response) => {
+    if (capturedHeaders || response.status() !== 200) return;
+    const request = response.request();
+    let url;
+    try { url = new URL(response.url()); } catch { return; }
+    // Capture only a successful Box directory response. The first Alidocs
+    // request after OAuth may still carry a stale token; freezing that request
+    // caused the scan to remain failed even after a later valid token arrived.
+    if (url.hostname !== "alidocs.dingtalk.com" || url.pathname !== "/box/api/v2/dentry/list") return;
     const h = await request.allHeaders().catch(() => request.headers());
-    if (capturedHeaders) return;
     if (!h["a-token"] || !h.cookie) return;
+    let body;
+    try { body = await response.json(); } catch { return; }
+    if (!body?.data?.spaceProfile) return;
     capturedHeaders = { ...h };
     delete capturedHeaders["content-length"];
     delete capturedHeaders["accept-encoding"];
     delete capturedHeaders["host"];
     s.state = s.state === "qr" ? "scanned" : "reusing";
-    finish(capturedHeaders);
+    void finish(capturedHeaders);
   };
   // Login may redirect the original tab or open another page. Listening on
   // the whole context keeps credential capture alive across both paths.
-  context.on("request", captureRequest);
+  context.on("response", captureResponse);
 
   // Read the QR directly from DingTalk's canvas. Do NOT screenshot the DOM:
   // Playwright element screenshots on a high-DPR page can apply the crop in
@@ -233,6 +246,16 @@ async function startSession(id, space) {
   await page.goto(SCAN_URL(space), { waitUntil: "domcontentloaded", timeout: 45000 }).catch(() => {});
 
   if (page.url().includes("login.dingtalk.com") && !capturedHeaders) {
+    // The current DingTalk login UI leaves QR "自动登录" unchecked. Without
+    // it, the phone can accept the scan while the waiting web challenge stays
+    // on the login page. Select only the visible QR-mode checkbox.
+    await page.evaluate(() => {
+      const target = [...document.querySelectorAll('.module-qrcode-op-item')].find((el) => {
+        const r = el.getBoundingClientRect();
+        return r.width > 0 && r.height > 0 && (el.textContent || '').trim() === '自动登录';
+      });
+      if (target?.querySelector('.dingtalk-login-icon-checkbox-undone')) target.click();
+    }).catch(() => {});
     // The canvas is rendered after DOMContentLoaded. Keep the public state at
     // starting until a real QR exists so the UI shows its generation loader,
     // never an empty "please scan" panel.
@@ -260,6 +283,7 @@ async function startSession(id, space) {
       }
     }, 8000);
     regrab.unref?.();
+    s.regrabTimer = regrab;
   }
 }
 
@@ -276,7 +300,10 @@ const server = http.createServer(async (req, res) => {
   try {
     if (req.method === "GET" && url.pathname === "/healthz") return send(200, { status: "ok", state_configured: Boolean(STATE_FILE) });
     if (req.method === "POST" && url.pathname === "/sessions") {
-      evictOld();
+      // One persistent profile must have exactly one owner. Close and await
+      // every prior context before creating the next challenge; this makes
+      // cancel/retry deterministic and prevents stale QR/polling state.
+      await closeAllSessions();
       const body = await readJson();
       const space = extractSpace(body.space) || VERIFY_SPACE;
       const id = crypto.randomBytes(9).toString("hex");
@@ -289,7 +316,7 @@ const server = http.createServer(async (req, res) => {
       const s = sessions.get(sessionMatch[1]);
       if (!s) return send(404, { error: "session_not_found" });
       if (req.method === "GET") return send(200, redacted(s));
-      if (req.method === "DELETE") { closeSession(sessionMatch[1]); return send(200, { status: "closed" }); }
+      if (req.method === "DELETE") { await closeSession(sessionMatch[1]); return send(200, { status: "closed" }); }
     }
     if (req.method === "POST" && (url.pathname === "/spaces/resolve" || url.pathname === "/spaces/add")) {
       const body = await readJson();