diff --git a/src/components/favorites/QueryFavorites.tsx b/src/components/favorites/QueryFavorites.tsx
index 7e5233e..3cfd1b8 100644
--- a/src/components/favorites/QueryFavorites.tsx
+++ b/src/components/favorites/QueryFavorites.tsx
@@ -36,6 +36,8 @@ export function QueryFavorites() {
   const [editDescValue, setEditDescValue] = useState("");
   const [showNewCategory, setShowNewCategory] = useState(false);
   const [newCategoryName, setNewCategoryName] = useState("");
+  const [pendingFavorite, setPendingFavorite] = useState<Favorite | null>(null);
+  const [showConfirm, setShowConfirm] = useState(false);
   const [pendingDelete, setPendingDelete] = useState<{ cat: string; count: number } | null>(
     null,
   );
@@ -67,7 +69,7 @@ export function QueryFavorites() {
     return groups;
   }, [filtered, categories]);
 
-  const handleClick = (fav: Favorite) => {
+  const openFavorite = (fav: Favorite) => {
     const store = useEditorStore.getState();
     const activeTab = store.tabs.find((t) => t.id === store.activeTabId);
     if (activeTab && activeTab.type === "query") {
@@ -78,6 +80,30 @@ export function QueryFavorites() {
     }
   };
 
+  const handleClick = (fav: Favorite) => {
+    const store = useEditorStore.getState();
+    const activeTab = store.tabs.find((t) => t.id === store.activeTabId);
+    if (activeTab?.type === "query" && activeTab.isDirty) {
+      setPendingFavorite(fav);
+      setShowConfirm(true);
+      return;
+    }
+    openFavorite(fav);
+  };
+
+  const handleConfirmReplace = () => {
+    if (pendingFavorite) {
+      openFavorite(pendingFavorite);
+    }
+    setPendingFavorite(null);
+    setShowConfirm(false);
+  };
+
+  const handleCancelReplace = () => {
+    setPendingFavorite(null);
+    setShowConfirm(false);
+  };
+
   const handleDoubleClick = (fav: Favorite) => {
     const store = useEditorStore.getState();
     const tabId = store.addTab();
@@ -389,6 +415,13 @@ export function QueryFavorites() {
         }}
         onCancel={() => setPendingDelete(null)}
       />
+      <ConfirmDialog
+        isOpen={showConfirm}
+        title="Replace current tab content?"
+        message="Unsaved changes will be lost."
+        onConfirm={handleConfirmReplace}
+        onCancel={handleCancelReplace}
+      />
     </div>
   );
 }
diff --git a/src/components/favorites/__tests__/QueryFavorites.test.tsx b/src/components/favorites/__tests__/QueryFavorites.test.tsx
index d6c79af..811e24b 100644
--- a/src/components/favorites/__tests__/QueryFavorites.test.tsx
+++ b/src/components/favorites/__tests__/QueryFavorites.test.tsx
@@ -2,9 +2,15 @@ import { fireEvent, render, screen } from "@testing-library/react";
 import { afterEach, beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
 import { QueryFavorites } from "../QueryFavorites";
 
-const { useFavoritesStoreFn } = vi.hoisted(() => {
-  return { useFavoritesStoreFn: vi.fn() };
-});
+const { useFavoritesStoreFn, updateTabContent, addTab, editorState } = vi.hoisted(() => ({
+  useFavoritesStoreFn: vi.fn(),
+  updateTabContent: vi.fn(),
+  addTab: vi.fn(() => "newTabId"),
+  editorState: {
+    tabs: [{ id: "tab1", type: "query", content: "", isDirty: false }],
+    activeTabId: "tab1",
+  },
+}));
 
 vi.mock("../../../stores/favoritesStore", () => ({
   useFavoritesStore: useFavoritesStoreFn,
@@ -13,10 +19,9 @@ vi.mock("../../../stores/favoritesStore", () => ({
 vi.mock("../../../stores/editorStore", () => ({
   useEditorStore: {
     getState: vi.fn(() => ({
-      tabs: [{ id: "tab1", type: "query", content: "" }],
-      activeTabId: "tab1",
-      addTab: vi.fn(() => "newTabId"),
-      updateTabContent: vi.fn(),
+      ...editorState,
+      addTab,
+      updateTabContent,
     })),
   },
 }));
@@ -106,6 +111,12 @@ beforeEach(() => {
   storeState.updateFavorite.mockClear();
   storeState.addCategory.mockClear();
   storeState.deleteCategory.mockClear();
+  updateTabContent.mockReset();
+  addTab.mockReset().mockReturnValue("newTabId");
+  editorState.tabs = [
+    { id: "tab1", type: "query", content: "", isDirty: false },
+  ];
+  editorState.activeTabId = "tab1";
 });
 
 afterEach(() => {
@@ -128,6 +139,50 @@ describe("QueryFavorites", () => {
     const { container } = render(<QueryFavorites />);
     expect(container.querySelector(".flex.h-full.flex-col")).toBeInTheDocument();
   });
+
+  it("confirms before replacing a dirty query tab", () => {
+    editorState.tabs = [
+      {
+        id: "tab1",
+        type: "query",
+        content: "SELECT unsaved_work",
+        isDirty: true,
+      },
+    ];
+    render(<QueryFavorites />);
+
+    fireEvent.click(screen.getByText("Get Active Users"));
+
+    expect(screen.getByText("Replace current tab content?")).toBeInTheDocument();
+    expect(screen.getByText("Unsaved changes will be lost.")).toBeInTheDocument();
+    expect(updateTabContent).not.toHaveBeenCalled();
+
+    fireEvent.click(screen.getByRole("button", { name: "Confirm" }));
+
+    expect(updateTabContent).toHaveBeenCalledWith(
+      "tab1",
+      "SELECT * FROM users WHERE active = 1",
+    );
+    expect(screen.queryByText("Unsaved changes will be lost.")).not.toBeInTheDocument();
+  });
+
+  it("keeps dirty query content when replacement is cancelled", () => {
+    editorState.tabs = [
+      {
+        id: "tab1",
+        type: "query",
+        content: "SELECT unsaved_work",
+        isDirty: true,
+      },
+    ];
+    render(<QueryFavorites />);
+
+    fireEvent.click(screen.getByText("Get Active Users"));
+    fireEvent.click(screen.getByRole("button", { name: "Cancel" }));
+
+    expect(updateTabContent).not.toHaveBeenCalled();
+    expect(screen.queryByText("Unsaved changes will be lost.")).not.toBeInTheDocument();
+  });
 });
 
 // ─────────────────────────────────────────────────────────────────────────
@@ -213,3 +268,52 @@ describe("QueryFavorites — delete category confirmation (#337)", () => {
     expect(screen.getByText("1 favorite will be moved to Uncategorized.")).toBeInTheDocument();
   });
 });
+
+// ─────────────────────────────────────────────────────────────────────────
+// Issue #341: confirm before overwriting a dirty editor tab.
+// ─────────────────────────────────────────────────────────────────────────
+describe("QueryFavorites — dirty-tab overwrite confirmation (#341)", () => {
+  it("confirms before replacing a dirty query tab", () => {
+    editorState.tabs = [
+      {
+        id: "tab1",
+        type: "query",
+        content: "SELECT unsaved_work",
+        isDirty: true,
+      },
+    ];
+    render(<QueryFavorites />);
+
+    fireEvent.click(screen.getByText("Get Active Users"));
+
+    expect(screen.getByText("Replace current tab content?")).toBeInTheDocument();
+    expect(screen.getByText("Unsaved changes will be lost.")).toBeInTheDocument();
+    expect(updateTabContent).not.toHaveBeenCalled();
+
+    fireEvent.click(screen.getByRole("button", { name: "Confirm" }));
+
+    expect(updateTabContent).toHaveBeenCalledWith(
+      "tab1",
+      "SELECT * FROM users WHERE active = 1",
+    );
+    expect(screen.queryByText("Unsaved changes will be lost.")).not.toBeInTheDocument();
+  });
+
+  it("keeps dirty query content when replacement is cancelled", () => {
+    editorState.tabs = [
+      {
+        id: "tab1",
+        type: "query",
+        content: "SELECT unsaved_work",
+        isDirty: true,
+      },
+    ];
+    render(<QueryFavorites />);
+
+    fireEvent.click(screen.getByText("Get Active Users"));
+    fireEvent.click(screen.getByRole("button", { name: "Cancel" }));
+
+    expect(updateTabContent).not.toHaveBeenCalled();
+    expect(screen.queryByText("Unsaved changes will be lost.")).not.toBeInTheDocument();
+  });
+});