test: validate mypy-diff CI for serialization fix

src/google/adk/events/event_actions.py

@@ -14,21 +14,42 @@
 
 from __future__ import annotations
 
+import json
 from typing import Any
+from typing import cast
 from typing import Optional
 
 from google.genai.types import Content
 from pydantic import alias_generators
 from pydantic import BaseModel
 from pydantic import ConfigDict
 from pydantic import Field
+from pydantic import field_serializer
 
 from ..auth.auth_tool import AuthConfig
 from ..tools.tool_confirmation import ToolConfirmation
 from .ui_widget import UiWidget
 
 
-class EventCompaction(BaseModel):
+def _make_json_serializable(obj: Any) -> Any:
+ """Recursively converts an object to a JSON-serializable form.
+
+ Non-serializable leaf values (e.g. Python callables stored in session state)
+ are replaced with a descriptive string so the overall structure can still be
+ persisted without crashing.
+ """
+ if isinstance(obj, dict):
+ return {k: _make_json_serializable(v) for k, v in obj.items()}
+ if isinstance(obj, (list, tuple)):
+ return [_make_json_serializable(v) for v in obj]
+ try:
+ json.dumps(obj)
+ return obj
+ except (TypeError, ValueError):
+ return f'<not serializable: {type(obj).__name__}>'
+
+
+class EventCompaction(BaseModel): # type: ignore[misc]
  """The compaction of the events."""
 
  model_config = ConfigDict(
@@ -48,7 +69,7 @@ class EventCompaction(BaseModel):
  """The compacted content of the events."""
 
 
-class EventActions(BaseModel):
+class EventActions(BaseModel): # type: ignore[misc]
  """Represents the actions attached to an event."""
 
  model_config = ConfigDict(
@@ -67,6 +88,10 @@ class EventActions(BaseModel):
  state_delta: dict[str, object] = Field(default_factory=dict)
  """Indicates that the event is updating the state with the given delta."""
 
+ @field_serializer('state_delta', mode='plain') # type: ignore[misc, untyped-decorator]
+ def _serialize_state_delta(self, value: dict[str, object]) -> dict[str, Any]:
+ return cast(dict[str, Any], _make_json_serializable(value))
+
  artifact_delta: dict[str, int] = Field(default_factory=dict)
  """Indicates that the event is updating an artifact. key is the filename,
  value is the version."""
@@ -107,6 +132,14 @@ class EventActions(BaseModel):
  """The agent state at the current event, used for checkpoint and resume. This
  should only be set by ADK workflow."""
 
+ @field_serializer('agent_state', mode='plain') # type: ignore[misc, untyped-decorator]
+ def _serialize_agent_state(
+ self, value: Optional[dict[str, Any]]
+ ) -> Optional[dict[str, Any]]:
+ if value is None:
+ return None
+ return cast(dict[str, Any], _make_json_serializable(value))
+
  rewind_before_invocation_id: Optional[str] = None
  """The invocation id to rewind to. This is only set for rewind event."""