fix: Fix issue where utility function get_tool_calls_and_descriptions_from_snapshot modifies agent_snapshot in place (#421)

* Fix issue where utility function modifies agent snapshot in place

* Pin lazy imports to be compatible with python 3.9

Author: sjrl

haystack_experimental/components/agents/human_in_the_loop/breakpoint.py

@@ -2,6 +2,8 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
+from copy import deepcopy
+
 from haystack.dataclasses.breakpoints import AgentSnapshot, ToolBreakpoint
 from haystack.utils import _deserialize_value_with_schema
 
@@ -31,7 +33,7 @@ def get_tool_calls_and_descriptions_from_snapshot(
     tool_caused_break_point = break_point.tool_name
 
     # Deserialize the tool invoker inputs from the snapshot
-    tool_invoker_inputs = _deserialize_value_with_schema(agent_snapshot.component_inputs["tool_invoker"])
+    tool_invoker_inputs = _deserialize_value_with_schema(deepcopy(agent_snapshot.component_inputs["tool_invoker"]))
     tool_call_messages = tool_invoker_inputs["messages"]
     state = tool_invoker_inputs["state"]
     tool_name_to_tool = {t.name: t for t in tool_invoker_inputs["tools"]}

pyproject.toml

@@ -29,6 +29,7 @@ classifiers = [
 dependencies = [
   "haystack-ai",
   "rich", # For pretty printing in the console used by human-in-the-loop utilities
+  "lazy-imports<1.2.0"  # 1.2.0 requires Python 3.10+, see https://github.com/bachorp/lazy-imports/releases/tag/1.2.0
 ]
 
 [project.urls]

test/components/agents/test_agent.py

@@ -2,6 +2,7 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
+import copy
 import os
 from pathlib import Path
 from typing import Any, Optional
@@ -12,13 +13,11 @@
 from haystack.components.generators.chat import OpenAIChatGenerator
 from haystack.core.errors import BreakpointException
 from haystack.core.pipeline.breakpoint import load_pipeline_snapshot
-from haystack.dataclasses import ChatMessage
+from haystack.dataclasses import ChatMessage, ToolCall
 from haystack.dataclasses.breakpoints import PipelineSnapshot
 from haystack.tools import Tool, create_tool_from_function
 
 from haystack_experimental.chat_message_stores.in_memory import InMemoryChatMessageStore
-from haystack_experimental.components.retrievers import ChatMessageRetriever
-from haystack_experimental.components.writers import ChatMessageWriter
 from haystack_experimental.components.agents.agent import Agent
 from haystack_experimental.components.agents.human_in_the_loop import (
     AlwaysAskPolicy,
@@ -34,6 +33,8 @@
 from haystack_experimental.components.agents.human_in_the_loop.breakpoint import (
     get_tool_calls_and_descriptions_from_snapshot,
 )
+from haystack_experimental.components.retrievers import ChatMessageRetriever
+from haystack_experimental.components.writers import ChatMessageWriter
 
 
 @pytest.fixture
@@ -50,6 +51,19 @@ def run(self, messages: list[ChatMessage], tools: Any) -> dict[str, list[ChatMes
         return {"replies": [ChatMessage.from_assistant("This is a mock response.")]}
 
 
+@component
+class MockChatGeneratorToolsResponse:
+    @component.output_types(replies=list[ChatMessage])
+    def run(self, messages: list[ChatMessage], tools: Any) -> dict[str, list[ChatMessage]]:
+        return {
+            "replies": [
+                ChatMessage.from_assistant(
+                    tool_calls=[ToolCall(tool_name="addition_tool", arguments={"a": 2, "b": 3})]
+                )
+            ]
+        }
+
+
 @component
 class MockAgent:
     def __init__(self, system_prompt: Optional[str] = None):
@@ -257,6 +271,35 @@ def test_from_dict(self, tools, confirmation_strategies, monkeypatch):
 
 
 class TestAgentConfirmationStrategy:
+    def test_get_tool_calls_and_descriptions_from_snapshot_no_mutation_of_snapshot(self, tools, tmp_path):
+        agent = Agent(
+            chat_generator=MockChatGeneratorToolsResponse(),
+            tools=tools,
+            confirmation_strategies={
+                "addition_tool": BreakpointConfirmationStrategy(snapshot_file_path=str(tmp_path)),
+            },
+        )
+        agent.warm_up()
+
+        # Run the agent to create a snapshot with a breakpoint
+        try:
+            agent.run([ChatMessage.from_user("What is 2+2?")])
+        except BreakpointException:
+            pass
+
+        # Load the latest snapshot from disk
+        loaded_snapshot = get_latest_snapshot(snapshot_file_path=str(tmp_path))
+
+        original_snapshot = copy.deepcopy(loaded_snapshot)
+
+        # Extract tool calls and descriptions
+        _ = get_tool_calls_and_descriptions_from_snapshot(
+            agent_snapshot=loaded_snapshot.agent_snapshot, breakpoint_tool_only=True
+        )
+
+        # Verify that the original snapshot has not been mutated
+        assert loaded_snapshot == original_snapshot
+
     @pytest.mark.skipif(not os.environ.get("OPENAI_API_KEY"), reason="OPENAI_API_KEY not set")
     @pytest.mark.integration
     def test_run_blocking_confirmation_strategy_modify(self, tools):