Add deepcopy() support to Chat instances (#96)

* Allow Chat instances to be deepcopied

* Update changelog

* Update chatlas/_chat.py

Co-authored-by: Copilot <[email protected]>

* Update types

---------

Co-authored-by: Copilot <[email protected]>

Author: cpsievert

CHANGELOG.md

@@ -11,7 +11,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changes
 
-* `ChatDatabricks()`'s `model` now defaults to `databricks-claude-3-7-sonnet` instead of `databricks-dbrx-instruct`
+* `ChatDatabricks()`'s `model` now defaults to `databricks-claude-3-7-sonnet` instead of `databricks-dbrx-instruct`. (#95)
+
+### Improvements
+
+* `Chat` instances can now be deep copied, which is useful for forking the chat session. (#96)
 
 ### Bug fixes
 

chatlas/_chat.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import copy
 import inspect
 import os
 import sys
@@ -1545,6 +1546,21 @@ def __repr__(self):
             res += "\n" + turn.__repr__(indent=2)
         return res + "\n"
 
+    def __deepcopy__(self, memo):
+        result = self.__class__.__new__(self.__class__)
+
+        # Avoid recursive references
+        memo[id(self)] = result
+
+        # Copy all attributes except the problematic provider attribute
+        for key, value in self.__dict__.items():
+            if key != "provider":
+                setattr(result, key, copy.deepcopy(value, memo))
+            else:
+                setattr(result, key, value)
+
+        return result
+
 
 class ChatResponse:
     """

chatlas/types/openai/_submit.py

@@ -70,6 +70,7 @@ class SubmitInputArgs(TypedDict, total=False):
             "gpt-4o-search-preview-2025-03-11",
             "gpt-4o-mini-search-preview-2025-03-11",
             "chatgpt-4o-latest",
+            "codex-mini-latest",
             "gpt-4o-mini",
             "gpt-4o-mini-2024-07-18",
             "gpt-4-turbo",

pyproject.toml

@@ -103,6 +103,10 @@ build-backend = "hatchling.build"
 [tool.hatch.version]
 source = "vcs"
 
+# Need this to have github refs in dependencies
+# [tool.hatch.metadata]
+# allow-direct-references = true
+
 [tool.hatch.build]
 skip-excluded-dirs = true
 

tests/test_chat.py

@@ -175,3 +175,20 @@ def test_json_serialize():
     # Completion objects, at least of right now, aren't included in the JSON
     turns[1].completion = None
     assert turns == turns_restored
+
+
+# Chat can be deepcopied/forked
+def test_deepcopy_chat():
+    import copy
+
+    chat = ChatOpenAI()
+    chat.chat("Hi", echo="none")
+    chat_fork = copy.deepcopy(chat)
+
+    assert len(chat.get_turns()) == 2
+    assert len(chat_fork.get_turns()) == 2
+
+    chat_fork.chat("Bye", echo="none")
+
+    assert len(chat.get_turns()) == 2
+    assert len(chat_fork.get_turns()) == 4