diff --git a/extension/dist/background.js b/extension/dist/background.js
index fa085bb6f..cf6eeb49f 100644
--- a/extension/dist/background.js
+++ b/extension/dist/background.js
@@ -759,6 +759,7 @@ const CONTAINER_TAB_GROUP_TITLE = {
   interactive: "OpenCLI Browser",
   automation: "OpenCLI Adapter"
 };
+const LEGACY_AUTOMATION_TAB_GROUP_TITLE = "OpenCLI";
 const AUTOMATION_TAB_GROUP_COLOR = "orange";
 let leaseMutationQueue = Promise.resolve();
 const ownedContainers = {
@@ -994,11 +995,70 @@ async function getOwnedContainerGroupId(role, windowId) {
     }
     container.groupId = null;
   }
-  const groups = await chrome.tabGroups.query({ windowId, title: CONTAINER_TAB_GROUP_TITLE[role] });
-  const existing = groups[0];
-  if (!existing) return null;
-  container.groupId = existing.id;
-  return existing.id;
+  for (const title of getOwnedContainerGroupTitles(role)) {
+    const groups = await chrome.tabGroups.query({ windowId, title });
+    const existing = groups[0];
+    if (existing) {
+      container.groupId = existing.id;
+      return existing.id;
+    }
+  }
+  return null;
+}
+function getOwnedContainerGroupTitles(role) {
+  return role === "automation" ? [CONTAINER_TAB_GROUP_TITLE.automation, LEGACY_AUTOMATION_TAB_GROUP_TITLE] : [CONTAINER_TAB_GROUP_TITLE.interactive];
+}
+async function focusOwnedWindowIfRequested(windowId, mode) {
+  if (mode !== "foreground") return;
+  const updateWindow = chrome.windows.update;
+  if (typeof updateWindow === "function") await updateWindow(windowId, { focused: true }).catch(() => {
+  });
+}
+async function toOwnedContainerDiscoveryCandidate(group) {
+  try {
+    const chromeWindow = await chrome.windows.get(group.windowId);
+    const reusableTabId = await findReusableOwnedContainerTab(group.windowId);
+    return {
+      windowId: group.windowId,
+      groupId: group.id,
+      focused: !!chromeWindow.focused,
+      hasReusableTab: reusableTabId !== void 0
+    };
+  } catch {
+    return null;
+  }
+}
+function selectOwnedContainerDiscoveryCandidate(candidates) {
+  if (candidates.length === 0) return null;
+  return [...candidates].sort((a, b) => {
+    if (a.focused !== b.focused) return a.focused ? -1 : 1;
+    if (a.hasReusableTab !== b.hasReusableTab) return a.hasReusableTab ? -1 : 1;
+    return a.groupId - b.groupId;
+  })[0];
+}
+async function discoverOwnedContainerFromTabGroup(role) {
+  const container = ownedContainers[role];
+  if (container.groupId !== null) {
+    try {
+      const group = await chrome.tabGroups.get(container.groupId);
+      await chrome.windows.get(group.windowId);
+      container.windowId = group.windowId;
+      return { windowId: group.windowId, groupId: group.id };
+    } catch {
+      container.windowId = null;
+      container.groupId = null;
+    }
+  }
+  for (const title of getOwnedContainerGroupTitles(role)) {
+    const groups = await chrome.tabGroups.query({ title });
+    const candidates = (await Promise.all(groups.map(toOwnedContainerDiscoveryCandidate))).filter((candidate) => candidate !== null);
+    const selected = selectOwnedContainerDiscoveryCandidate(candidates);
+    if (!selected) continue;
+    container.windowId = selected.windowId;
+    container.groupId = selected.groupId;
+    return { windowId: selected.windowId, groupId: selected.groupId };
+  }
+  return null;
 }
 async function ensureOwnedContainerTabGroup(role, windowId, tabIds) {
   const ids = [...new Set(tabIds.filter((id) => id !== void 0))];
@@ -1038,11 +1098,7 @@ async function ensureOwnedContainerWindowUnlocked(role, initialUrl, mode = "back
   if (container.windowId !== null) {
     try {
       await chrome.windows.get(container.windowId);
-      if (mode === "foreground") {
-        const updateWindow = chrome.windows.update;
-        if (typeof updateWindow === "function") await updateWindow(container.windowId, { focused: true }).catch(() => {
-        });
-      }
+      await focusOwnedWindowIfRequested(container.windowId, mode);
       const initialTabId2 = await findReusableOwnedContainerTab(container.windowId);
       await ensureOwnedContainerTabGroup(role, container.windowId, [initialTabId2]);
       return {
@@ -1054,6 +1110,17 @@ async function ensureOwnedContainerWindowUnlocked(role, initialUrl, mode = "back
       container.groupId = null;
     }
   }
+  const discovered = await discoverOwnedContainerFromTabGroup(role);
+  if (discovered) {
+    await focusOwnedWindowIfRequested(discovered.windowId, mode);
+    const initialTabId2 = await findReusableOwnedContainerTab(discovered.windowId);
+    await ensureOwnedContainerTabGroup(role, discovered.windowId, [initialTabId2]);
+    await persistRuntimeState();
+    return {
+      windowId: discovered.windowId,
+      initialTabId: initialTabId2
+    };
+  }
   const startUrl = initialUrl && isSafeNavigationUrl(initialUrl) ? initialUrl : BLANK_PAGE;
   const win = await chrome.windows.create({
     url: startUrl,
diff --git a/extension/src/background.test.ts b/extension/src/background.test.ts
index 551db2162..7ab75bb81 100644
--- a/extension/src/background.test.ts
+++ b/extension/src/background.test.ts
@@ -158,7 +158,7 @@ function createChromeMock() {
       onEvent: { addListener: vi.fn() } as Listener<(source: any, method: string, params: any) => void>,
     },
     windows: {
-      get: vi.fn(async (windowId: number) => ({ id: windowId })),
+      get: vi.fn(async (windowId: number) => ({ id: windowId, focused: windowId === lastFocusedWindowId })),
       create: vi.fn(async ({ url, focused, width, height, type }: any) => ({ id: 1, url, focused, width, height, type })),
       remove: vi.fn(async (_windowId: number) => {}),
       onRemoved: { addListener: vi.fn() } as Listener<(windowId: number) => void>,
@@ -187,7 +187,15 @@ function createChromeMock() {
     },
   };
 
-  return { chrome, tabs, groups, query, create, update };
+  return {
+    chrome,
+    tabs,
+    groups,
+    query,
+    create,
+    update,
+    setLastFocusedWindowId: (windowId: number) => { lastFocusedWindowId = windowId; },
+  };
 }
 
 describe('background tab isolation', () => {
@@ -908,7 +916,7 @@ describe('background tab isolation', () => {
     const { chrome } = createChromeMock();
     chrome.windows.get = vi.fn(async (windowId: number) => {
       if (windowId === 90 || windowId === 91) throw new Error(`stale window ${windowId}`);
-      return { id: windowId };
+      return { id: windowId, focused: false };
     });
     vi.stubGlobal('chrome', chrome);
 
@@ -1050,6 +1058,166 @@ describe('background tab isolation', () => {
     expect(chrome.tabGroups.update).not.toHaveBeenCalled();
   });
 
+  it('discovers and reuses an existing OpenCLI Adapter group in another window before creating one', async () => {
+    const { chrome, tabs, groups } = createChromeMock();
+    tabs.push({
+      id: 77,
+      windowId: 7,
+      url: 'about:blank',
+      title: 'blank',
+      active: true,
+      status: 'complete',
+      groupId: -1,
+    });
+    groups.push({
+      id: 99,
+      windowId: 7,
+      title: 'OpenCLI Adapter',
+      color: 'orange',
+      collapsed: true,
+    });
+    vi.stubGlobal('chrome', chrome);
+
+    const mod = await import('./background');
+    const tabId = await mod.__test__.resolveTabId(undefined, adapterKey('twitter'));
+
+    expect(tabId).toBe(77);
+    expect(chrome.windows.create).not.toHaveBeenCalled();
+    expect(mod.__test__.getAutomationWindowId(adapterKey('twitter'))).toBe(7);
+    expect(tabs.find((tab) => tab.id === 77)?.groupId).toBe(99);
+    expect(chrome.tabs.group).toHaveBeenCalledWith({ groupId: 99, tabIds: [77] });
+    expect(chrome.tabGroups.update).not.toHaveBeenCalled();
+  });
+
+  it('prefers a focused OpenCLI Adapter group when multiple matching groups exist', async () => {
+    const { chrome, tabs, groups, setLastFocusedWindowId } = createChromeMock();
+    setLastFocusedWindowId(8);
+    tabs.push({
+      id: 77,
+      windowId: 7,
+      url: 'about:blank',
+      title: 'blank',
+      active: true,
+      status: 'complete',
+      groupId: -1,
+    });
+    tabs.push({
+      id: 78,
+      windowId: 8,
+      url: 'about:blank',
+      title: 'blank',
+      active: true,
+      status: 'complete',
+      groupId: -1,
+    });
+    groups.push(
+      {
+        id: 99,
+        windowId: 7,
+        title: 'OpenCLI Adapter',
+        color: 'orange',
+        collapsed: true,
+      },
+      {
+        id: 98,
+        windowId: 8,
+        title: 'OpenCLI Adapter',
+        color: 'orange',
+        collapsed: true,
+      },
+    );
+    vi.stubGlobal('chrome', chrome);
+
+    const mod = await import('./background');
+    const tabId = await mod.__test__.resolveTabId(undefined, adapterKey('twitter'));
+
+    expect(tabId).toBe(78);
+    expect(chrome.windows.create).not.toHaveBeenCalled();
+    expect(mod.__test__.getAutomationWindowId(adapterKey('twitter'))).toBe(8);
+    expect(tabs.find((tab) => tab.id === 78)?.groupId).toBe(98);
+    expect(chrome.tabs.group).toHaveBeenCalledWith({ groupId: 98, tabIds: [78] });
+  });
+
+  it('prefers an OpenCLI Adapter group with a reusable debuggable tab when none are focused', async () => {
+    const { chrome, tabs, groups, setLastFocusedWindowId } = createChromeMock();
+    setLastFocusedWindowId(2);
+    tabs.push({
+      id: 77,
+      windowId: 7,
+      url: 'chrome://settings',
+      title: 'settings',
+      active: true,
+      status: 'complete',
+      groupId: -1,
+    });
+    tabs.push({
+      id: 78,
+      windowId: 8,
+      url: 'about:blank',
+      title: 'blank',
+      active: true,
+      status: 'complete',
+      groupId: -1,
+    });
+    groups.push(
+      {
+        id: 97,
+        windowId: 7,
+        title: 'OpenCLI Adapter',
+        color: 'orange',
+        collapsed: true,
+      },
+      {
+        id: 98,
+        windowId: 8,
+        title: 'OpenCLI Adapter',
+        color: 'orange',
+        collapsed: true,
+      },
+    );
+    vi.stubGlobal('chrome', chrome);
+
+    const mod = await import('./background');
+    const tabId = await mod.__test__.resolveTabId(undefined, adapterKey('twitter'));
+
+    expect(tabId).toBe(78);
+    expect(chrome.windows.create).not.toHaveBeenCalled();
+    expect(mod.__test__.getAutomationWindowId(adapterKey('twitter'))).toBe(8);
+    expect(tabs.find((tab) => tab.id === 78)?.groupId).toBe(98);
+    expect(chrome.tabs.group).toHaveBeenCalledWith({ groupId: 98, tabIds: [78] });
+  });
+
+  it('discovers and reuses a legacy OpenCLI automation group before creating a duplicate', async () => {
+    const { chrome, tabs, groups } = createChromeMock();
+    tabs.push({
+      id: 78,
+      windowId: 8,
+      url: 'about:blank',
+      title: 'blank',
+      active: true,
+      status: 'complete',
+      groupId: -1,
+    });
+    groups.push({
+      id: 98,
+      windowId: 8,
+      title: 'OpenCLI',
+      color: 'orange',
+      collapsed: true,
+    });
+    vi.stubGlobal('chrome', chrome);
+
+    const mod = await import('./background');
+    const tabId = await mod.__test__.resolveTabId(undefined, adapterKey('twitter'));
+
+    expect(tabId).toBe(78);
+    expect(chrome.windows.create).not.toHaveBeenCalled();
+    expect(mod.__test__.getAutomationWindowId(adapterKey('twitter'))).toBe(8);
+    expect(tabs.find((tab) => tab.id === 78)?.groupId).toBe(98);
+    expect(chrome.tabs.group).toHaveBeenCalledWith({ groupId: 98, tabIds: [78] });
+    expect(chrome.tabGroups.update).not.toHaveBeenCalled();
+  });
+
   it('reuses a persisted automation group id after service worker restart even if the user renamed it', async () => {
     const { chrome, tabs, groups } = createChromeMock();
     groups.push({
diff --git a/extension/src/background.ts b/extension/src/background.ts
index 2925c13bc..57f51e4c0 100644
--- a/extension/src/background.ts
+++ b/extension/src/background.ts
@@ -204,6 +204,7 @@ const CONTAINER_TAB_GROUP_TITLE: Record<OwnedWindowRole, string> = {
   interactive: 'OpenCLI Browser',
   automation: 'OpenCLI Adapter',
 };
+const LEGACY_AUTOMATION_TAB_GROUP_TITLE = 'OpenCLI';
 const AUTOMATION_TAB_GROUP_COLOR: chrome.tabGroups.ColorEnum = 'orange';
 let leaseMutationQueue: Promise<void> = Promise.resolve();
 const ownedContainers: Record<OwnedWindowRole, {
@@ -491,11 +492,87 @@ async function getOwnedContainerGroupId(role: OwnedWindowRole, windowId: number)
     container.groupId = null;
   }
 
-  const groups = await chrome.tabGroups.query({ windowId, title: CONTAINER_TAB_GROUP_TITLE[role] });
-  const existing = groups[0];
-  if (!existing) return null;
-  container.groupId = existing.id;
-  return existing.id;
+  for (const title of getOwnedContainerGroupTitles(role)) {
+    const groups = await chrome.tabGroups.query({ windowId, title });
+    const existing = groups[0];
+    if (existing) {
+      container.groupId = existing.id;
+      return existing.id;
+    }
+  }
+  return null;
+}
+
+function getOwnedContainerGroupTitles(role: OwnedWindowRole): string[] {
+  return role === 'automation'
+    ? [CONTAINER_TAB_GROUP_TITLE.automation, LEGACY_AUTOMATION_TAB_GROUP_TITLE]
+    : [CONTAINER_TAB_GROUP_TITLE.interactive];
+}
+
+type OwnedContainerDiscoveryCandidate = {
+  windowId: number;
+  groupId: number;
+  focused: boolean;
+  hasReusableTab: boolean;
+};
+
+async function focusOwnedWindowIfRequested(windowId: number, mode: WindowMode): Promise<void> {
+  if (mode !== 'foreground') return;
+  const updateWindow = (chrome.windows as unknown as { update?: (windowId: number, updateInfo: { focused?: boolean }) => Promise<unknown> }).update;
+  if (typeof updateWindow === 'function') await updateWindow(windowId, { focused: true }).catch(() => {});
+}
+
+async function toOwnedContainerDiscoveryCandidate(group: chrome.tabGroups.TabGroup): Promise<OwnedContainerDiscoveryCandidate | null> {
+  try {
+    const chromeWindow = await chrome.windows.get(group.windowId);
+    const reusableTabId = await findReusableOwnedContainerTab(group.windowId);
+    return {
+      windowId: group.windowId,
+      groupId: group.id,
+      focused: !!chromeWindow.focused,
+      hasReusableTab: reusableTabId !== undefined,
+    };
+  } catch {
+    // Ignore stale browser-session group/window state and keep looking.
+    return null;
+  }
+}
+
+function selectOwnedContainerDiscoveryCandidate(candidates: OwnedContainerDiscoveryCandidate[]): OwnedContainerDiscoveryCandidate | null {
+  if (candidates.length === 0) return null;
+  return [...candidates].sort((a, b) => {
+    if (a.focused !== b.focused) return a.focused ? -1 : 1;
+    if (a.hasReusableTab !== b.hasReusableTab) return a.hasReusableTab ? -1 : 1;
+    return a.groupId - b.groupId;
+  })[0];
+}
+
+async function discoverOwnedContainerFromTabGroup(role: OwnedWindowRole): Promise<{ windowId: number; groupId: number } | null> {
+  const container = ownedContainers[role];
+  if (container.groupId !== null) {
+    try {
+      const group = await chrome.tabGroups.get(container.groupId);
+      await chrome.windows.get(group.windowId);
+      container.windowId = group.windowId;
+      return { windowId: group.windowId, groupId: group.id };
+    } catch {
+      container.windowId = null;
+      container.groupId = null;
+    }
+  }
+
+  for (const title of getOwnedContainerGroupTitles(role)) {
+    const groups = await chrome.tabGroups.query({ title });
+    const candidates = (await Promise.all(groups.map(toOwnedContainerDiscoveryCandidate)))
+      .filter((candidate): candidate is OwnedContainerDiscoveryCandidate => candidate !== null);
+    const selected = selectOwnedContainerDiscoveryCandidate(candidates);
+    if (!selected) continue;
+    container.windowId = selected.windowId;
+    container.groupId = selected.groupId;
+    return { windowId: selected.windowId, groupId: selected.groupId };
+  }
+
+  return null;
 }
 
 async function ensureOwnedContainerTabGroup(role: OwnedWindowRole, windowId: number, tabIds: Array<number | undefined>): Promise<void> {
@@ -560,10 +637,7 @@ async function ensureOwnedContainerWindowUnlocked(
   if (container.windowId !== null) {
     try {
       await chrome.windows.get(container.windowId);
-      if (mode === 'foreground') {
-        const updateWindow = (chrome.windows as unknown as { update?: (windowId: number, updateInfo: { focused?: boolean }) => Promise<unknown> }).update;
-        if (typeof updateWindow === 'function') await updateWindow(container.windowId, { focused: true }).catch(() => {});
-      }
+      await focusOwnedWindowIfRequested(container.windowId, mode);
       const initialTabId = await findReusableOwnedContainerTab(container.windowId);
       await ensureOwnedContainerTabGroup(role, container.windowId, [initialTabId]);
       return {
@@ -576,6 +650,18 @@ async function ensureOwnedContainerWindowUnlocked(
     }
   }
 
+  const discovered = await discoverOwnedContainerFromTabGroup(role);
+  if (discovered) {
+    await focusOwnedWindowIfRequested(discovered.windowId, mode);
+    const initialTabId = await findReusableOwnedContainerTab(discovered.windowId);
+    await ensureOwnedContainerTabGroup(role, discovered.windowId, [initialTabId]);
+    await persistRuntimeState();
+    return {
+      windowId: discovered.windowId,
+      initialTabId,
+    };
+  }
+
   const startUrl = (initialUrl && isSafeNavigationUrl(initialUrl)) ? initialUrl : BLANK_PAGE;
 
   // Note: Do NOT set `state` parameter here. Chrome 146+ rejects 'normal' as an invalid