diff --git a/extension/src/background.test.ts b/extension/src/background.test.ts
index f9368251..f15964f1 100644
--- a/extension/src/background.test.ts
+++ b/extension/src/background.test.ts
@@ -73,6 +73,12 @@ function createChromeMock() {
         if (!tab) throw new Error(`Unknown tab ${tabId}`);
         return tab;
       }),
+      move: vi.fn(async (tabId: number, moveProps: { windowId: number; index: number }) => {
+        const tab = tabs.find((entry) => entry.id === tabId);
+        if (!tab) throw new Error(`Unknown tab ${tabId}`);
+        tab.windowId = moveProps.windowId;
+        return tab;
+      }),
       onUpdated: { addListener: vi.fn(), removeListener: vi.fn() } as Listener<(id: number, info: chrome.tabs.TabChangeInfo) => void>,
     },
     windows: {
@@ -219,6 +225,39 @@ describe('background tab isolation', () => {
     }));
   });
 
+  it('moves drifted tab back to automation window instead of creating a new one', async () => {
+    const { chrome, tabs } = createChromeMock();
+    // Tab 1 belongs to automation window 1 but drifted to window 2
+    tabs[0].windowId = 2;
+    tabs[0].url = 'https://twitter.com/home';
+    vi.stubGlobal('chrome', chrome);
+
+    const mod = await import('./background');
+    mod.__test__.setAutomationWindowId('site:twitter', 1);
+
+    const tabId = await mod.__test__.resolveTabId(1, 'site:twitter');
+
+    // Should have moved tab 1 back to window 1 and reused it
+    expect(chrome.tabs.move).toHaveBeenCalledWith(1, { windowId: 1, index: -1 });
+    expect(tabId).toBe(1);
+  });
+
+  it('falls through to re-resolve when drifted tab move fails', async () => {
+    const { chrome, tabs } = createChromeMock();
+    tabs[0].windowId = 2;
+    tabs[0].url = 'https://twitter.com/home';
+    // Make move fail
+    chrome.tabs.move = vi.fn(async () => { throw new Error('Cannot move tab'); });
+    vi.stubGlobal('chrome', chrome);
+
+    const mod = await import('./background');
+    mod.__test__.setAutomationWindowId('site:twitter', 1);
+
+    // Should still resolve (by finding/creating a tab in the correct window)
+    const tabId = await mod.__test__.resolveTabId(1, 'site:twitter');
+    expect(typeof tabId).toBe('number');
+  });
+
   it('idle timeout closes the automation window for site:notebooklm', async () => {
     const { chrome, tabs } = createChromeMock();
     tabs[0].url = 'https://notebooklm.google.com/';
diff --git a/extension/src/background.ts b/extension/src/background.ts
index a9d0439e..29766cd0 100644
--- a/extension/src/background.ts
+++ b/extension/src/background.ts
@@ -350,8 +350,19 @@ async function resolveTab(tabId: number | undefined, workspace: string, initialU
       const session = automationSessions.get(workspace);
       const matchesSession = session ? tab.windowId === session.windowId : false;
       if (isDebuggableUrl(tab.url) && matchesSession) return { tabId, tab };
-      if (session && !matchesSession) {
-        console.warn(`[opencli] Tab ${tabId} is not bound to workspace ${workspace}, re-resolving`);
+      if (session && !matchesSession && isDebuggableUrl(tab.url)) {
+        // Tab drifted to another window but content is still valid.
+        // Try to move it back instead of abandoning it.
+        console.warn(`[opencli] Tab ${tabId} drifted to window ${tab.windowId}, moving back to ${session.windowId}`);
+        try {
+          await chrome.tabs.move(tabId, { windowId: session.windowId, index: -1 });
+          const moved = await chrome.tabs.get(tabId);
+          if (moved.windowId === session.windowId && isDebuggableUrl(moved.url)) {
+            return { tabId, tab: moved };
+          }
+        } catch (moveErr) {
+          console.warn(`[opencli] Failed to move tab back: ${moveErr}`);
+        }
       } else if (!isDebuggableUrl(tab.url)) {
         console.warn(`[opencli] Tab ${tabId} URL is not debuggable (${tab.url}), re-resolving`);
       }
@@ -502,7 +513,22 @@ async function handleNavigate(cmd: Command, workspace: string): Promise<Result>
     }, 15000);
   });
 
-  const tab = await chrome.tabs.get(tabId);
+  let tab = await chrome.tabs.get(tabId);
+
+  // Post-navigation drift detection: if the tab moved to another window
+  // during navigation (e.g. a tab-management extension regrouped it),
+  // try to move it back to maintain session isolation.
+  const session = automationSessions.get(workspace);
+  if (session && tab.windowId !== session.windowId) {
+    console.warn(`[opencli] Tab ${tabId} drifted to window ${tab.windowId} during navigation, moving back to ${session.windowId}`);
+    try {
+      await chrome.tabs.move(tabId, { windowId: session.windowId, index: -1 });
+      tab = await chrome.tabs.get(tabId);
+    } catch (moveErr) {
+      console.warn(`[opencli] Failed to recover drifted tab: ${moveErr}`);
+    }
+  }
+
   return {
     id: cmd.id,
     ok: true,
diff --git a/extension/src/cdp.ts b/extension/src/cdp.ts
index 4e37179b..cbb8b2f7 100644
--- a/extension/src/cdp.ts
+++ b/extension/src/cdp.ts
@@ -79,6 +79,16 @@ export async function ensureAttached(tabId: number, aggressiveRetry: boolean = f
   }
 
   if (lastError) {
+    // Log detailed diagnostics for debugging extension conflicts
+    let finalUrl = 'unknown';
+    let finalWindowId = 'unknown';
+    try {
+      const tab = await chrome.tabs.get(tabId);
+      finalUrl = tab.url ?? 'undefined';
+      finalWindowId = String(tab.windowId);
+    } catch { /* tab gone */ }
+    console.warn(`[opencli] attach failed for tab ${tabId}: url=${finalUrl}, windowId=${finalWindowId}, error=${lastError}`);
+
     const hint = lastError.includes('chrome-extension://')
       ? '. Tip: another Chrome extension may be interfering — try disabling other extensions'
       : '';