fix: strip final tags from session messages

src/agents/session-tool-result-guard.test.ts

@@ -142,4 +142,26 @@ describe("installSessionToolResultGuard", () => {
       .map((e) => (e as { message: AgentMessage }).message);
     expect(messages.map((m) => m.role)).toEqual(["assistant", "toolResult"]);
   });
+
+  it("strips <final> tags from assistant text blocks", () => {
+    const sm = SessionManager.inMemory();
+    installSessionToolResultGuard(sm);
+
+    sm.appendMessage({
+      role: "assistant",
+      content: [
+        { type: "text", text: "<final>Hey!</final>" },
+        { type: "text", text: "More <final>text</final> here." },
+      ],
+    } as AgentMessage);
+
+    const messages = sm
+      .getEntries()
+      .filter((e) => e.type === "message")
+      .map((e) => (e as { message: AgentMessage }).message);
+
+    const assistant = messages[0] as { content?: Array<{ type?: string; text?: string }> };
+    expect(assistant.content?.[0]?.text).toBe("Hey!");
+    expect(assistant.content?.[1]?.text).toBe("More text here.");
+  });
 });