diff --git a/frontend-web/src/core/page-layout/chats-iframe-route.test.mjs b/frontend-web/src/core/page-layout/chats-iframe-route.test.mjs
index 4d237adb..246c2d70 100644
--- a/frontend-web/src/core/page-layout/chats-iframe-route.test.mjs
+++ b/frontend-web/src/core/page-layout/chats-iframe-route.test.mjs
@@ -45,14 +45,37 @@ test("requires an explicit chatMode=iframe opt-in for the Brainy page", () => {
   assert.equal(isExplicitBrainyIframeMode("chatMode=IFRAME"), true);
 });
 
-test("redirects accidental chats_iframe routes to standard full chat", () => {
+test("upgrades legacy iframe-source routes to the iframe protocol", () => {
   assert.equal(
     resolveStandardChatFallback(
       "/page/workspace/chats_iframe/new",
       "?from=iframe&hideChrome=1",
     ),
-    "/page/workspace/chats/new?hideChrome=1&chatMode=full",
+    "/page/workspace/chats_iframe/new?from=iframe&hideChrome=1&chatMode=iframe",
   );
+});
+
+test("honors an explicit chat mode over the legacy iframe source", () => {
+  assert.equal(
+    resolveStandardChatFallback(
+      "/page/workspace/chats_iframe/new",
+      "?from=iframe&chatMode=full",
+    ),
+    "/page/workspace/chats/new?chatMode=full",
+  );
+});
+
+test("treats a blank chat mode as absent for the legacy iframe source", () => {
+  assert.equal(
+    resolveStandardChatFallback(
+      "/page/workspace/chats_iframe/new",
+      "?from=iframe&chatMode=%20%20",
+    ),
+    "/page/workspace/chats_iframe/new?from=iframe&chatMode=iframe",
+  );
+});
+
+test("redirects chats_iframe routes without the iframe source to standard full chat", () => {
   assert.equal(
     resolveStandardChatFallback(
       "/page/workspace/chats_iframe/thread-123",
@@ -121,17 +144,17 @@ test("forces the iframe theme on the login route without changing normal login",
 test("preserves the iframe theme in the post-login redirect", () => {
   assert.equal(
     buildChatsIframeRedirectPath("?from=iframe&theme=dark-blue"),
-    "/page/workspace/chats_iframe/new?from=iframe&theme=dark-blue",
+    "/page/workspace/chats_iframe/new?from=iframe&chatMode=iframe&theme=dark-blue",
   );
   assert.equal(
     buildChatsIframeRedirectPath("?from=iframe"),
-    "/page/workspace/chats_iframe/new?from=iframe",
+    "/page/workspace/chats_iframe/new?from=iframe&chatMode=iframe",
   );
   assert.equal(
     buildChatsIframeRedirectPath(
       "?from=iframe&theme=dark-blue&ticket=secret&authToken=secret",
     ),
-    "/page/workspace/chats_iframe/new?from=iframe&theme=dark-blue",
+    "/page/workspace/chats_iframe/new?from=iframe&chatMode=iframe&theme=dark-blue",
   );
 });
 
@@ -141,7 +164,7 @@ test("keeps the iframe redirect ahead of login-method fallbacks", () => {
       "?from=iframe&theme=dark-blue&yUserId=user-1",
       "/page/workspace/chats/new",
     ),
-    "/page/workspace/chats_iframe/new?from=iframe&theme=dark-blue",
+    "/page/workspace/chats_iframe/new?from=iframe&chatMode=iframe&theme=dark-blue",
   );
   assert.equal(
     resolvePostLoginRedirectPath("?yUserId=user-1", "/page/workspace/chats/new"),
@@ -156,7 +179,7 @@ test("preserves iframe theme when a new chat becomes a thread", () => {
       "thread-123",
       "?from=iframe&theme=dark-blue&ticket=secret",
     ),
-    "/page/workspace/chats_iframe/thread-123?from=iframe&theme=dark-blue",
+    "/page/workspace/chats_iframe/thread-123?from=iframe&chatMode=iframe&theme=dark-blue",
   );
 });
 
diff --git a/frontend-web/src/core/page-layout/chats-iframe-route.ts b/frontend-web/src/core/page-layout/chats-iframe-route.ts
index 2868b00d..aadfb64d 100644
--- a/frontend-web/src/core/page-layout/chats-iframe-route.ts
+++ b/frontend-web/src/core/page-layout/chats-iframe-route.ts
@@ -23,7 +23,13 @@ export function buildChatsIframeRedirectPath(search: string): string {
     target.set("from", IFRAME_LOGIN_SOURCE);
   }
 
-  if (isExplicitBrainyIframeMode(search)) {
+  const requestedMode = source.get("chatMode")?.trim();
+  if (requestedMode) {
+    target.set("chatMode", requestedMode);
+  } else if (isChatsIframeLogin(search)) {
+    // Plugin links historically identify this protocol with `from=iframe`.
+    // Normalize that legacy marker into the explicit mode before handing the
+    // URL to the workspace route, so it does not fall back to the full chat.
     target.set("chatMode", "iframe");
   }
 
@@ -89,21 +95,25 @@ export function resolveStandardChatFallback(
   pathname: string,
   search: string,
 ): string | null {
-  if (
-    !isChatsIframeWorkspacePath(pathname) ||
-    isExplicitBrainyIframeMode(search)
-  ) {
+  if (!isChatsIframeWorkspacePath(pathname) || isExplicitBrainyIframeMode(search)) {
     return null;
   }
 
+  const normalizedSearch = search.startsWith("?") ? search.slice(1) : search;
+  const params = new URLSearchParams(normalizedSearch);
+  const requestedMode = params.get("chatMode")?.trim();
+  if (isChatsIframeLogin(search) && !requestedMode) {
+    params.set("chatMode", "iframe");
+    const targetSearch = params.toString();
+    return targetSearch ? `${pathname}?${targetSearch}` : pathname;
+  }
+
   const routePrefix = "/page/workspace/chats_iframe/";
   const routeSuffix = pathname.slice(routePrefix.length);
   const targetPath =
     routeSuffix && routeSuffix !== "new"
       ? `/page/workspace/chats/${routeSuffix}`
       : "/page/workspace/chats/new";
-  const normalizedSearch = search.startsWith("?") ? search.slice(1) : search;
-  const params = new URLSearchParams(normalizedSearch);
   params.delete("from");
   params.set("chatMode", "full");
   const targetSearch = params.toString();
diff --git a/frontend-web/src/pages/IframeChatPage.tsx b/frontend-web/src/pages/IframeChatPage.tsx
index ca66cb18..4bf84389 100644
--- a/frontend-web/src/pages/IframeChatPage.tsx
+++ b/frontend-web/src/pages/IframeChatPage.tsx
@@ -1,7 +1,6 @@
 "use client";
 
 import {
-  ArrowRightIcon,
   BookMarkedIcon,
   BotIcon,
   BrainCircuitIcon,
@@ -709,7 +708,7 @@ export default function IframeChatPage() {
                   <div className="mb-6 flex min-h-40 flex-col items-center justify-center px-4 text-center">
                     <div className="text-2xl font-medium">你好</div>
                     <div className="mt-2 text-sm text-muted-foreground">
-                      选择智能体进入问答，或直接使用通用问答
+                      选择智能体进入问答
                     </div>
                     <div className="mt-4 flex flex-wrap items-center justify-center gap-2">
                       <label className="relative inline-flex h-9 min-w-40 items-center rounded-full border border-[#eee3d5] bg-[#fffaf5] px-3 text-[#7e6a57] shadow-sm transition-colors hover:bg-white">
@@ -740,21 +739,10 @@ export default function IframeChatPage() {
                           ▾
                         </span>
                       </label>
-                      <Button
-                        type="button"
-                        variant="outline"
-                        size="sm"
-                        disabled={isUploading}
-                        onClick={() => enterStandardChat()}
-                        className="rounded-full"
-                      >
-                        直接进入通用问答
-                        <ArrowRightIcon className="ml-1 size-3.5" />
-                      </Button>
                     </div>
                     {!selectorLoading && fallbackAgents.length === 0 && (
                       <div className="mt-3 text-xs text-muted-foreground">
-                        暂无可选智能体，仍可直接进入通用问答
+                        暂无可选智能体
                       </div>
                     )}
                   </div>
diff --git a/frontend-web/src/pages/LoginPage.tsx b/frontend-web/src/pages/LoginPage.tsx
index 7262ce3d..5acae55c 100644
--- a/frontend-web/src/pages/LoginPage.tsx
+++ b/frontend-web/src/pages/LoginPage.tsx
@@ -76,7 +76,6 @@ function summarizeStoredUserInfo(): Record<string, unknown> | null {
 }
 
 const DEFAULT_USERNAME = 'guest';
-const IFRAME_LOGIN_SOURCE = 'iframe';
 const IFRAME_CHAT_MODE = 'iframe';
 const DEFAULT_REDIRECT_PATH = '/page/workspace/chats/new';
 const FULL_CHAT_MODE = 'full';
@@ -104,15 +103,13 @@ export default function LoginPage() {
     searchParams.get('chatMode')?.trim().toLowerCase() ?? '';
   const brainyIframeRequested = requestedChatMode === IFRAME_CHAT_MODE;
   // Wujie is an application container, not the Brainy iframe protocol. It
-  // must therefore land on the regular full ChatPage. Legacy `from=iframe`
-  // links now do the same; only the explicit `chatMode=iframe` protocol opt-in
-  // is allowed to open IframeChatPage.
+  // must therefore land on the regular full ChatPage. Plugin links with
+  // `from=iframe` are normalized into the explicit iframe protocol mode.
   const fullChatRequested = useMemo(
     () =>
       !brainyIframeRequested &&
       (isWujieEnv() ||
-        requestedChatMode === FULL_CHAT_MODE ||
-        searchParams.get('from') === IFRAME_LOGIN_SOURCE),
+        requestedChatMode === FULL_CHAT_MODE),
     [brainyIframeRequested, requestedChatMode, searchParams],
   );
   const isIframeLogin = useMemo(