fix: CLI context pollution between sessions

extensions/cli/src/session.test.ts

@@ -360,7 +360,7 @@ describe("SessionManager", () => {
       const firstSession = createSession();
       const firstSessionId = firstSession.sessionId;
 
-      vi.mocked(uuidv4).mockReturnValue("new-uuid-456" as any);
+      vi.mocked(uuidv4).mockReturnValue("new-uuid-456");
 
       const secondSession = startNewSession();
 
@@ -381,7 +381,7 @@ describe("SessionManager", () => {
         },
       ];
 
-      vi.mocked(uuidv4).mockReturnValue("new-uuid-789" as any);
+      vi.mocked(uuidv4).mockReturnValue("new-uuid-789");
 
       const session = startNewSession(history);
 
@@ -392,7 +392,7 @@ describe("SessionManager", () => {
     it("should set the new session as current", () => {
       const originalSession = createSession();
 
-      vi.mocked(uuidv4).mockReturnValue("new-session-id" as any);
+      vi.mocked(uuidv4).mockReturnValue("new-session-id");
 
       const newSession = startNewSession();
       const currentSession = getCurrentSession();
@@ -401,4 +401,100 @@ describe("SessionManager", () => {
       expect(currentSession).not.toBe(originalSession);
     });
   });
+
+  describe("session isolation", () => {
+    it("should not pollute new sessions with previous session history", () => {
+      // Simulate first CLI session
+      vi.mocked(uuidv4).mockReturnValue("session-1");
+      const session1 = createSession();
+      const history1: ChatHistoryItem[] = [
+        {
+          message: {
+            role: "user",
+            content: "Tell me about dogs",
+          },
+          contextItems: [],
+        },
+        {
+          message: {
+            role: "assistant",
+            content: "Dogs are loyal companions...",
+          },
+          contextItems: [],
+        },
+      ];
+      updateSessionHistory(history1);
+
+      // Simulate starting a new CLI session (without --resume)
+      vi.mocked(uuidv4).mockReturnValue("session-2");
+      const session2 = startNewSession([]);
+
+      // New session should have clean state
+      expect(session2.sessionId).toBe("session-2");
+      expect(session2.sessionId).not.toBe(session1.sessionId);
+      expect(session2.history).toEqual([]);
+      expect(session2.history.length).toBe(0);
+    });
+
+    it("should create independent sessions for concurrent operations", () => {
+      // Create first session with some data
+      vi.mocked(uuidv4).mockReturnValue("concurrent-1");
+      const session1 = createSession();
+      updateSessionTitle("Session 1");
+      updateSessionHistory([
+        {
+          message: {
+            role: "user",
+            content: "First session message",
+          },
+          contextItems: [],
+        },
+      ]);
+
+      // Start a new session
+      vi.mocked(uuidv4).mockReturnValue("concurrent-2");
+      const session2 = startNewSession([]);
+
+      // Verify session2 is clean
+      expect(session2.title).toBe("Untitled Session");
+      expect(session2.history).toEqual([]);
+      expect(session2.sessionId).not.toBe(session1.sessionId);
+    });
+
+    it("should properly clear session state when transitioning between sessions", () => {
+      // First session with complex history
+      vi.mocked(uuidv4).mockReturnValue("complex-session-1");
+      const session1 = createSession();
+      updateSessionTitle("Complex Session");
+      const complexHistory: ChatHistoryItem[] = [
+        {
+          message: {
+            role: "user",
+            content: "What were we discussing?",
+          },
+          contextItems: [],
+        },
+        {
+          message: {
+            role: "assistant",
+            content: "We were discussing dogs earlier.",
+          },
+          contextItems: [],
+        },
+      ];
+      updateSessionHistory(complexHistory);
+
+      // Verify first session has data
+      expect(getCurrentSession().history.length).toBe(2);
+
+      // Start fresh session
+      vi.mocked(uuidv4).mockReturnValue("fresh-session-2");
+      const session2 = startNewSession([]);
+
+      // Verify clean state
+      expect(session2.history.length).toBe(0);
+      expect(session2.title).toBe("Untitled Session");
+      expect(getCurrentSession().sessionId).toBe("fresh-session-2");
+    });
+  });
 });