Fix Agent unintentionally modifying stream for all Prompt Drivers

CHANGELOG.md

@@ -7,10 +7,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
-## Fixed
-
-- Exception when calling `Structure.to_json()` after it has run.
-
 ### Added
 
 - `PromptTask.conversation_memory` for setting the Conversation Memory on a Prompt Task.
@@ -19,6 +15,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `BranchTask` for selecting which Tasks (if any) to run based on a condition.
 - Support for `BranchTask` in `StructureVisualizer`.
 
+### Fixed
+
+- Exception when calling `Structure.to_json()` after it has run.
+- `Agent` unintentionally modifying `stream` for all Prompt Drivers.
+
 ## [1.0.0] - 2024-12-09
 
 ### Added

griptape/structures/agent.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from copy import copy
 from typing import TYPE_CHECKING, Callable, Optional, Union
 
 from attrs import Attribute, Factory, define, field
@@ -38,18 +39,20 @@ def validate_fail_fast(self, _: Attribute, fail_fast: bool) -> None:  # noqa: FB
     def __attrs_post_init__(self) -> None:
         super().__attrs_post_init__()
 
-        self.prompt_driver.stream = self.stream
+        # Make a copy to avoid unintentionally modifying the global default Prompt Driver's stream setting
+        prompt_driver = copy(self.prompt_driver)
+        prompt_driver.stream = self.stream
         if len(self.tasks) == 0:
             if self.tools:
                 task = ToolkitTask(
                     self.input,
-                    prompt_driver=self.prompt_driver,
+                    prompt_driver=prompt_driver,
                     tools=self.tools,
                     max_meta_memory_entries=self.max_meta_memory_entries,
                 )
             else:
                 task = PromptTask(
-                    self.input, prompt_driver=self.prompt_driver, max_meta_memory_entries=self.max_meta_memory_entries
+                    self.input, prompt_driver=prompt_driver, max_meta_memory_entries=self.max_meta_memory_entries
                 )
 
             self.add_task(task)

tests/unit/structures/test_agent.py

@@ -276,3 +276,11 @@ def test_is_running(self):
         task.state = BaseTask.State.RUNNING
 
         assert agent.is_running()
+
+    def test_stream_mutation(self):
+        prompt_driver = MockPromptDriver()
+        agent = Agent(prompt_driver=MockPromptDriver(), stream=True)
+
+        assert isinstance(agent.tasks[0], PromptTask)
+        assert agent.tasks[0].prompt_driver.stream is True
+        assert agent.tasks[0].prompt_driver is not prompt_driver