fix: fail closed when a BEFORE_LLM rewrite does not end with a user message

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/praisonai-agents/praisonaiagents/agent/chat_mixin.py

@@ -2081,8 +2081,13 @@ Your Goal: {self.goal}"""
             if isinstance(messages[0], dict) and messages[0].get("role") == "system":
                 system = messages.pop(0).get("content")
             last = messages.pop() if messages else {}
+            if not isinstance(last, dict) or last.get("role") != "user":
+                # ``LLM.get_response`` always sends the prompt as a user turn; fail closed
+                # rather than silently re-role a rewritten assistant/tool message.
+                logging.warning(f"Agent {self.name} BEFORE_LLM rewrite must end with a user message")
+                return llm_kwargs, "[LLM request blocked by hook: rewritten messages must end with a user message]"
             llm_kwargs = {**llm_kwargs, 'system_prompt': system, 'chat_history': messages,
-                          'prompt': last.get("content") if isinstance(last, dict) else last}
+                          'prompt': last.get("content")}
         return llm_kwargs, None
 
     def _custom_llm_after_input(self, llm_kwargs, response, tally, start_time):

src/praisonai-agents/tests/unit/agent/test_llm_hooks_custom_llm_path.py

@@ -122,3 +122,16 @@ def test_before_llm_message_rewrite_reaches_the_provider(calls):
     assert sent[0]["role"] == "system"
     assert all("my secret" not in str(m.get("content")) for m in sent)
     assert any(m.get("content") == "[redacted]" for m in sent)
+
+
+def test_rewrite_ending_in_non_user_message_fails_closed(calls):
+    registry = HookRegistry()
+
+    def append_assistant(data):
+        messages = list(data.messages) + [{"role": "assistant", "content": "injected"}]
+        return HookResult(decision="allow", modified_input={"messages": messages})
+
+    registry.register_function(HookEvent.BEFORE_LLM, append_assistant, sequential=True)
+    result = _agent(registry).chat("hi")
+    assert calls["n"] == 0
+    assert "must end with a user message" in result