diff --git a/background/signup-flow-helpers.js b/background/signup-flow-helpers.js
index 0009105..35f372e 100644
--- a/background/signup-flow-helpers.js
+++ b/background/signup-flow-helpers.js
@@ -36,22 +36,9 @@
         return null;
       }
 
-      if (typeof chrome?.tabs?.get === 'function' && typeof chrome?.windows?.update === 'function') {
-        try {
-          const tab = await chrome.tabs.get(tabId);
-          const windowId = Number(tab?.windowId);
-          if (Number.isInteger(windowId) && windowId >= 0) {
-            await chrome.windows.update(windowId, { state: 'normal', focused: true }).catch(() => {});
-            await chrome.windows.update(windowId, {
-              focused: true,
-              width: 1200,
-              height: 900,
-            }).catch(() => {});
-          }
-        } catch {
-          // Best-effort only. Step 2 still has content-side entry retries.
-        }
-      }
+      // Do not request window focus here. The automation tab is already
+      // locked to the selected Chrome window; raising that window would
+      // interrupt the user's active workspace.
 
       if (typeof addLog === 'function') {
         await addLog(
diff --git a/background/steps/submit-signup-email.js b/background/steps/submit-signup-email.js
index 49e75f0..c484f09 100644
--- a/background/steps/submit-signup-email.js
+++ b/background/steps/submit-signup-email.js
@@ -185,31 +185,11 @@
       });
     }
 
-    async function normalizeSignupTabWindowForStep2(tabId) {
-      if (
-        !Number.isInteger(tabId)
-        || typeof chrome?.tabs?.get !== 'function'
-        || typeof chrome?.windows?.update !== 'function'
-      ) {
-        return;
-      }
-
-      try {
-        const tab = await chrome.tabs.get(tabId);
-        const windowId = Number(tab?.windowId);
-        if (!Number.isInteger(windowId) || windowId < 0) {
-          return;
-        }
-
-        await chrome.windows.update(windowId, { state: 'normal', focused: true }).catch(() => {});
-        await chrome.windows.update(windowId, {
-          focused: true,
-          width: 1200,
-          height: 900,
-        }).catch(() => {});
-      } catch {
-        // Best-effort only: content-side retries still handle layout recovery.
-      }
+    async function keepSignupTabWindowInBackgroundForStep2(tabId) {
+      // Intentionally no-op: the task tab is locked to the selected Chrome
+      // window by the tab-runtime layer. Step 2 must not focus/raise that
+      // window while the user is working in another app or browser window.
+      void tabId;
     }
 
     async function ensureSignupPhoneEntryReady(tabId) {
@@ -257,7 +237,7 @@
         signupTabId = (await ensureSignupEntryPageReady(2)).tabId;
       } else {
         await chrome.tabs.update(signupTabId, { active: true });
-        await normalizeSignupTabWindowForStep2(signupTabId);
+        await keepSignupTabWindowInBackgroundForStep2(signupTabId);
         await waitForStep2SignupTabToSettle(
           signupTabId,
           '步骤 2：已切换到注册页标签，正在等待页面加载完成并额外稳定 3 秒...'
diff --git a/tests/background-signup-step2-branching.test.js b/tests/background-signup-step2-branching.test.js
index 7a3b663..864f685 100644
--- a/tests/background-signup-step2-branching.test.js
+++ b/tests/background-signup-step2-branching.test.js
@@ -442,7 +442,12 @@ test('step 2 waits for the existing signup tab to settle before probing the entr
         update: async () => {
           events.push('tab-update');
         },
-        get: async () => ({ url: 'https://chatgpt.com/' }),
+        get: async () => ({ id: 17, windowId: 91, url: 'https://chatgpt.com/' }),
+      },
+      windows: {
+        update: async () => {
+          throw new Error('step 2 must not focus or raise the automation window');
+        },
       },
     },
     completeStepFromBackground: async (step, payload) => {
@@ -565,6 +570,16 @@ test('signup flow helper waits for the signup entry tab to settle for step 2 bef
       logs.push({ message, level, meta });
     },
     buildGeneratedAliasEmail: () => '',
+    chrome: {
+      tabs: {
+        get: async () => ({ id: 23, windowId: 92, url: 'https://chatgpt.com/' }),
+      },
+      windows: {
+        update: async () => {
+          throw new Error('signup entry helper must not focus or raise the automation window');
+        },
+      },
+    },
     ensureContentScriptReadyOnTab: async () => {
       events.push('content-ready');
     },