fix: Add Pydantic v2 compatibility for OpenAPI/Swagger UI endpoints

src/google/adk/cli/adk_web_server.py

@@ -86,6 +86,8 @@
 from ..sessions.base_session_service import BaseSessionService
 from ..sessions.session import Session
 from ..utils.context_utils import Aclosing
+from ..utils.pydantic_v2_compatibility import create_robust_openapi_function
+from ..utils.pydantic_v2_compatibility import patch_types_for_pydantic_v2
 from .cli_eval import EVAL_SESSION_ID_PREFIX
 from .utils import cleanup
 from .utils import common
@@ -686,6 +688,13 @@ async def internal_lifespan(app: FastAPI):
     tracer_provider = trace.get_tracer_provider()
     register_processors(tracer_provider)
 
+    # Apply Pydantic v2 compatibility patches before creating FastAPI app
+    patches_applied = patch_types_for_pydantic_v2()
+    if patches_applied:
+      logger.info("Pydantic v2 compatibility patches applied successfully")
+    else:
+      logger.warning("Pydantic v2 compatibility patches could not be applied")
+
     # Run the FastAPI server.
     app = FastAPI(lifespan=internal_lifespan)
 
@@ -698,6 +707,12 @@ async def internal_lifespan(app: FastAPI):
           allow_headers=["*"],
       )
 
+    # Replace default OpenAPI function with robust version
+    app.openapi = create_robust_openapi_function(app)
+    logger.info(
+        "Robust OpenAPI generation enabled with Pydantic v2 error handling"
+    )
+
     @app.get("/list-apps")
     async def list_apps() -> list[str]:
       return self.agent_loader.list_agents()