Modernize codebase for Python 3.10+ (#1223)

* Modernize codebase for Python 3.10+

- Update type hints to use X | Y instead of Union[X, Y]
- Replace Optional[T] with T | None throughout codebase
- Fix forward reference type annotations to work with pipe operator
- Keep Union for TypedDict fields with forward references (required)
- All tests passing with modern syntax

This prepares for Pydantic AI v1.0 which will require Python 3.10+

* Fix type annotation for _SessionLocal

The sessionmaker itself can be None, not the sessions it creates.
Changed from async_sessionmaker[AsyncSession | None] to
async_sessionmaker[AsyncSession] | None

Co-authored-by: Copilot <175728472+copilot-pull-request-reviewer[bot]@users.noreply.github.com>

* Fix jsonschema test compatibility with Union type

The test expects dataclass fields to use typing.Union which has __origin__
attribute. The new pipe syntax (field_type | None) creates types.UnionType
which doesn't have __origin__.

Keep using Union[field_type, None] for dynamically generated dataclass fields
to maintain backward compatibility with existing tests and user code that may
depend on the __origin__ attribute.

* lil tweak

---------

Co-authored-by: Copilot <175728472+copilot-pull-request-reviewer[bot]@users.noreply.github.com>

Author: zzstoatzz

CLAUDE.md

@@ -39,7 +39,7 @@ Marvin is a lightweight AI engineering toolkit for building natural language int
 ### Finding Things
 - Use `rg` for searching, not grep
 - Use `ls` and `tree` for navigation
-- Check git context with `gh` and `git` commands
+- Check git context with using the GitHub MCP server
 - Think like a hacker with good intentions - search in site-packages when needed
 
 ### Linter Philosophy

docs/api-reference/marvin-agents-actor.mdx

@@ -35,7 +35,7 @@ class Actor(name: str, instructions: str | None = None, description: str | None
   ```
 - **`get_current`**
   ```python
-  def get_current(cls) -> Optional[Actor]
+  def get_current(cls) -> Actor | None
   ```
   Get the current actor from context.
 - **`get_end_turn_tools`**

docs/api-reference/marvin-engine-orchestrator.mdx

@@ -35,7 +35,7 @@ class Orchestrator(tasks: list[Task[Any]], thread: Thread | str | None = None, h
       - ready: tasks that are ready to be run
 - **`get_current`**
   ```python
-  def get_current(cls) -> Optional[Orchestrator]
+  def get_current(cls) -> Orchestrator | None
   ```
   Get the current orchestrator from context.
 - **`handle_event`**

docs/api-reference/marvin-thread.mdx

@@ -107,7 +107,7 @@ Main runtime object for managing conversation context.
   Add a user message to the thread.
 - **`get_current`**
   ```python
-  def get_current(cls) -> Optional[Thread]
+  def get_current(cls) -> Thread | None
   ```
   Get the current thread from context.
 - **`get_llm_calls`**

docs/api-reference/marvin-utilities-jsonschema.mdx

@@ -79,7 +79,7 @@ Create a field with simplified default handling.
 
 ### `create_numeric_type`
 ```python
-def create_numeric_type(base: Type[Union[int, float]], schema: Mapping[str, Any]) -> type | Annotated[Any, ...]
+def create_numeric_type(base: Type[int | float], schema: Mapping[str, Any]) -> type | Annotated[Any, ...]
 ```
 Create numeric type with optional constraints.
 

docs/api-reference/marvin-utilities-types.mdx

@@ -96,12 +96,12 @@ Attributes:
     function (Callable): The original function object.
     signature (inspect.Signature): The signature object of the function.
     name (str): The name of the function.
-    docstring (Optional[str]): The docstring of the function.
+    docstring (str | None): The docstring of the function.
     parameters (List[ParameterModel]): The parameters of the function.
-    return_annotation (Optional[Any]): The return annotation of the function.
+    return_annotation (Any | None): The return annotation of the function.
     source_code (str): The source code of the function.
     bound_parameters (dict[str, Any]): The parameters of the function bound with values.
-    return_value (Optional[Any]): The return value of the function call.
+    return_value (Any | None): The return value of the function call.
 
 **Methods:**
 

src/marvin/_internal/deprecation.py

@@ -7,7 +7,7 @@
 import functools
 import warnings
 from datetime import datetime, timedelta
-from typing import Any, Callable, Optional, TypeVar
+from typing import Any, Callable, TypeVar
 
 from typing_extensions import ParamSpec
 
@@ -22,8 +22,8 @@ class MarvinDeprecationWarning(DeprecationWarning):
 
 def generate_deprecation_message(
     name: str,
-    start_date: Optional[datetime] = None,
-    end_date: Optional[datetime] = None,
+    start_date: datetime | None = None,
+    end_date: datetime | None = None,
     help: str = "",
 ) -> str:
     """Generate a deprecation warning message."""
@@ -45,8 +45,8 @@ def generate_deprecation_message(
 
 def deprecated_class(
     *,
-    start_date: Optional[datetime] = None,
-    end_date: Optional[datetime] = None,
+    start_date: datetime | None = None,
+    end_date: datetime | None = None,
     stacklevel: int = 2,
     help: str = "",
 ) -> Callable[[type[T]], type[T]]:
@@ -85,8 +85,8 @@ def new_init(self: T, *args: Any, **kwargs: Any) -> None:
 
 def deprecated_callable(
     *,
-    start_date: Optional[datetime] = None,
-    end_date: Optional[datetime] = None,
+    start_date: datetime | None = None,
+    end_date: datetime | None = None,
     stacklevel: int = 2,
     help: str = "",
 ) -> Callable[[Callable[P, R]], Callable[P, R]]:

src/marvin/agents/actor.py

@@ -4,7 +4,7 @@
 from contextvars import ContextVar
 from dataclasses import dataclass, field
 from pathlib import Path
-from typing import TYPE_CHECKING, Any, Optional, Sequence, TypeVar
+from typing import TYPE_CHECKING, Any, Sequence, TypeVar
 
 import pydantic_ai
 from pydantic_ai.agent import AgentRunResult
@@ -22,7 +22,7 @@
     from marvin.handlers.handlers import AsyncHandler, Handler
 T = TypeVar("T")
 # Global context var for current actor
-_current_actor: ContextVar[Optional["Actor"]] = ContextVar(
+_current_actor: ContextVar["Actor | None"] = ContextVar(
     "current_actor",
     default=None,
 )
@@ -79,7 +79,7 @@ def __exit__(self, exc_type: Any, exc_val: Any, exc_tb: Any):
             _current_actor.reset(self._tokens.pop())
 
     @classmethod
-    def get_current(cls) -> Optional["Actor"]:
+    def get_current(cls) -> "Actor | None":
         """Get the current actor from context."""
         return _current_actor.get()
 

src/marvin/engine/orchestrator.py

@@ -4,7 +4,7 @@
 from contextvars import ContextVar
 from dataclasses import dataclass
 from pathlib import Path
-from typing import Any, Literal, Optional, Sequence, TypeVar
+from typing import Any, Literal, Sequence, TypeVar
 
 from pydantic_ai.agent import AgentRunResult
 from pydantic_ai.mcp import MCPServer
@@ -348,7 +348,7 @@ async def _get_messages(
         return user_prompt, [system_prompt] + message_history
 
     @classmethod
-    def get_current(cls) -> Optional["Orchestrator"]:
+    def get_current(cls) -> "Orchestrator | None":
         """Get the current orchestrator from context."""
         return _current_orchestrator.get()
 

src/marvin/memory/providers/postgres.py

@@ -1,5 +1,5 @@
 import uuid
-from typing import Dict, Optional
+from typing import Dict
 
 # async pg
 import anyio
@@ -103,8 +103,8 @@ class PostgresMemory(MemoryProvider):
     )
 
     # We'll store an async engine + session factory:
-    _engine: Optional[AsyncEngine] = None
-    _SessionLocal: Optional[async_sessionmaker[AsyncSession]] = None
+    _engine: AsyncEngine | None = None
+    _SessionLocal: async_sessionmaker[AsyncSession] | None = None
 
     # Cache for dynamically generated table classes
     _table_class_cache: Dict[str, Base] = {}