feat: add artifacts logic (#8)

backend/src/tools/builtins/present_file_tool.py

@@ -1,8 +1,19 @@
-from langchain.tools import tool
+from typing import Annotated
+
+from langchain.tools import InjectedToolCallId, ToolRuntime, tool
+from langchain_core.messages import ToolMessage
+from langgraph.types import Command
+from langgraph.typing import ContextT
+
+from src.agents.thread_state import ThreadState
 
 
 @tool("present_files", parse_docstring=True)
-def present_file_tool(filepaths: list[str]) -> str:
+def present_file_tool(
+    runtime: ToolRuntime[ContextT, ThreadState],
+    filepaths: list[str],
+    tool_call_id: Annotated[str, InjectedToolCallId],
+) -> Command:
     """Make files visible to the user for viewing and rendering in the client interface.
 
     When to use the present_files tool:
@@ -22,4 +33,9 @@ def present_file_tool(filepaths: list[str]) -> str:
     Args:
         filepaths: List of absolute file paths to present to the user. **Only** files in `/mnt/user-data/outputs` can be presented.
     """
-    return "OK"
+    existing_artifacts = runtime.state.get("artifacts") or []
+    new_artifacts = existing_artifacts + filepaths
+    runtime.state["artifacts"] = new_artifacts
+    return Command(
+        update={"artifacts": new_artifacts, "messages": [ToolMessage("Successfully presented files", tool_call_id=tool_call_id)]},
+    )