diff --git a/autogpt_platform/frontend/src/app/(platform)/build/components/BuilderChatPanel/__tests__/useBuilderChatPanel.test.ts b/autogpt_platform/frontend/src/app/(platform)/build/components/BuilderChatPanel/__tests__/useBuilderChatPanel.test.ts
index d1d4504df4..7711314fc2 100644
--- a/autogpt_platform/frontend/src/app/(platform)/build/components/BuilderChatPanel/__tests__/useBuilderChatPanel.test.ts
+++ b/autogpt_platform/frontend/src/app/(platform)/build/components/BuilderChatPanel/__tests__/useBuilderChatPanel.test.ts
@@ -359,6 +359,39 @@ describe("useBuilderChatPanel – flowID reset", () => {
 
     expect(result.current.sessionError).toBe(false);
   });
+
+  it("always clears messages on flowID change even when a cached session exists (prevents applied/unapplied mismatch)", async () => {
+    mockPostV2CreateSession.mockResolvedValue({
+      status: 200,
+      data: { id: "sess-cached" },
+    });
+    mockFlowID = "flow-1";
+
+    const { result, rerender } = renderHook(() => useBuilderChatPanel());
+
+    await openAndFlush(() => result.current.handleToggle());
+    expect(result.current.sessionId).toBe("sess-cached");
+
+    // Simulate chat messages from the first session
+    mockChatMessages = [
+      {
+        id: "msg-1",
+        role: "assistant",
+        parts: [{ type: "text", text: "Hello from session 1" }],
+      },
+    ];
+    mockSetMessages.mockClear();
+
+    // Navigate away and back to the same graph — cached session should be restored
+    // but messages must be cleared to stay in sync with the reset appliedActionKeys
+    mockFlowID = "flow-2";
+    rerender();
+    mockFlowID = "flow-1";
+    rerender();
+
+    // setMessages([]) must be called unconditionally regardless of cached session
+    expect(mockSetMessages).toHaveBeenCalledWith([]);
+  });
 });
 
 describe("useBuilderChatPanel – apply does not trigger cache refetch", () => {
diff --git a/autogpt_platform/frontend/src/app/(platform)/build/components/BuilderChatPanel/useBuilderChatPanel.ts b/autogpt_platform/frontend/src/app/(platform)/build/components/BuilderChatPanel/useBuilderChatPanel.ts
index 8a6a89efd4..099fe10edf 100644
--- a/autogpt_platform/frontend/src/app/(platform)/build/components/BuilderChatPanel/useBuilderChatPanel.ts
+++ b/autogpt_platform/frontend/src/app/(platform)/build/components/BuilderChatPanel/useBuilderChatPanel.ts
@@ -122,8 +122,10 @@ export function useBuilderChatPanel({
   const setEdges = useEdgeStore((s) => s.setEdges);
 
   // When the user navigates to a different graph: restore the cached session for
-  // that graph (preserving conversation history) and reset per-session UI state.
-  // Messages are only cleared when there is no prior session for the new graph.
+  // that graph (preserving the backend session) and reset all per-session UI state.
+  // Messages are always cleared on navigation — appliedActionKeys cannot be persisted
+  // so restoring messages while resetting action state would show previously applied
+  // actions as unapplied, allowing them to be re-applied and creating duplicate undo entries.
   useEffect(() => {
     const cachedSessionId = flowID
       ? (graphSessionCache.get(flowID) ?? null)
@@ -136,9 +138,7 @@ export function useBuilderChatPanel({
     isCreatingSessionRef.current = false;
     processedToolCallsRef.current = new Set();
     hasSentSeedMessageRef.current = false;
-    if (!cachedSessionId) {
-      setMessages([]);
-    }
+    setMessages([]);
     // setMessages is a stable function from useChat; excluding from deps is safe.
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [flowID]);