feat(middleware): detect file intent in chat messages

surfsense_backend/tests/unit/middleware/test_file_intent_middleware.py

@@ -0,0 +1,116 @@
+import pytest
+from langchain_core.messages import AIMessage, HumanMessage
+
+from app.agents.new_chat.middleware.file_intent import (
+    FileIntentMiddleware,
+    FileOperationIntent,
+)
+
+pytestmark = pytest.mark.unit
+
+
+class _FakeLLM:
+    def __init__(self, response_text: str):
+        self._response_text = response_text
+
+    async def ainvoke(self, *_args, **_kwargs):
+        return AIMessage(content=self._response_text)
+
+
+@pytest.mark.asyncio
+async def test_file_write_intent_injects_contract_message():
+    llm = _FakeLLM(
+        '{"intent":"file_write","confidence":0.93,"suggested_filename":"ideas.md"}'
+    )
+    middleware = FileIntentMiddleware(llm=llm)
+    state = {
+        "messages": [HumanMessage(content="Create another random note for me")],
+        "turn_id": "123:456",
+    }
+
+    result = await middleware.abefore_agent(state, runtime=None)  # type: ignore[arg-type]
+
+    assert result is not None
+    contract = result["file_operation_contract"]
+    assert contract["intent"] == FileOperationIntent.FILE_WRITE.value
+    assert contract["suggested_path"] == "/ideas.md"
+    assert contract["turn_id"] == "123:456"
+    assert any(
+        "file_operation_contract" in str(msg.content)
+        for msg in result["messages"]
+        if hasattr(msg, "content")
+    )
+
+
+@pytest.mark.asyncio
+async def test_non_write_intent_does_not_inject_contract_message():
+    llm = _FakeLLM(
+        '{"intent":"file_read","confidence":0.88,"suggested_filename":null}'
+    )
+    middleware = FileIntentMiddleware(llm=llm)
+    original_messages = [HumanMessage(content="Read /notes.md")]
+    state = {"messages": original_messages, "turn_id": "abc:def"}
+
+    result = await middleware.abefore_agent(state, runtime=None)  # type: ignore[arg-type]
+
+    assert result is not None
+    assert result["file_operation_contract"]["intent"] == FileOperationIntent.FILE_READ.value
+    assert "messages" not in result
+
+
+@pytest.mark.asyncio
+async def test_file_write_null_filename_uses_semantic_default_path():
+    llm = _FakeLLM(
+        '{"intent":"file_write","confidence":0.74,"suggested_filename":null}'
+    )
+    middleware = FileIntentMiddleware(llm=llm)
+    state = {
+        "messages": [HumanMessage(content="create a random markdown file")],
+        "turn_id": "turn:1",
+    }
+
+    result = await middleware.abefore_agent(state, runtime=None)  # type: ignore[arg-type]
+
+    assert result is not None
+    contract = result["file_operation_contract"]
+    assert contract["intent"] == FileOperationIntent.FILE_WRITE.value
+    assert contract["suggested_path"] == "/notes.md"
+
+
+@pytest.mark.asyncio
+async def test_file_write_null_filename_infers_json_extension():
+    llm = _FakeLLM(
+        '{"intent":"file_write","confidence":0.71,"suggested_filename":null}'
+    )
+    middleware = FileIntentMiddleware(llm=llm)
+    state = {
+        "messages": [HumanMessage(content="create a sample json config file")],
+        "turn_id": "turn:2",
+    }
+
+    result = await middleware.abefore_agent(state, runtime=None)  # type: ignore[arg-type]
+
+    assert result is not None
+    contract = result["file_operation_contract"]
+    assert contract["intent"] == FileOperationIntent.FILE_WRITE.value
+    assert contract["suggested_path"] == "/notes.json"
+
+
+@pytest.mark.asyncio
+async def test_file_write_txt_suggestion_is_normalized_to_markdown():
+    llm = _FakeLLM(
+        '{"intent":"file_write","confidence":0.82,"suggested_filename":"random.txt"}'
+    )
+    middleware = FileIntentMiddleware(llm=llm)
+    state = {
+        "messages": [HumanMessage(content="create a random file")],
+        "turn_id": "turn:3",
+    }
+
+    result = await middleware.abefore_agent(state, runtime=None)  # type: ignore[arg-type]
+
+    assert result is not None
+    contract = result["file_operation_contract"]
+    assert contract["intent"] == FileOperationIntent.FILE_WRITE.value
+    assert contract["suggested_path"] == "/random.md"
+