[change] Migrate TaskSearchRequest/FluentTasks, DataContractSpec yaml, test parity

- Add v9 TaskSearchRequest (msgspec.Struct) with json() method
- Add v9 FluentTasks that produces v9 DSL and TaskSearchRequest
- Add from_yaml()/to_yaml() to v9 DataContractSpec
- Update test_task_client.py to use v9 models
- Update open_lineage_test.py to use v9 FluentTasks
- Update data_contract_test.py to use v9 DataContractSpec
- Fix imports in atlan_fields_test, data_quality_rule_test, workflow_client
- Document test_packages.py legacy Asset import (ClassVar fields)
- Port v9 test files: credential, custom relationships, workflow, etc.
- Client layer: validate_arguments migration, msgspec Struct support
- Formatting changes

All 7650 tests pass (1852 v9 + 5798 legacy)

Author: Aryamanz29

pyatlan/client/admin.py

@@ -1,8 +1,6 @@
 # SPDX-License-Identifier: Apache-2.0
 # Copyright 2025 Atlan Pte. Ltd.
 
-from pyatlan.validate import validate_arguments
-
 from pyatlan.client.common import AdminGetAdminEvents, AdminGetKeycloakEvents, ApiCaller
 from pyatlan.errors import ErrorCode
 from pyatlan.model.keycloak_events import (
@@ -11,6 +9,7 @@
     KeycloakEventRequest,
     KeycloakEventResponse,
 )
+from pyatlan.validate import validate_arguments
 
 
 class AdminClient:

pyatlan/client/aio/admin.py

@@ -1,8 +1,6 @@
 # SPDX-License-Identifier: Apache-2.0
 # Copyright 2025 Atlan Pte. Ltd.
 
-from pyatlan.validate import validate_arguments
-
 from pyatlan.client.common import (
     AdminGetAdminEvents,
     AdminGetKeycloakEvents,
@@ -14,6 +12,7 @@
     AsyncKeycloakEventResponse,
 )
 from pyatlan.model.keycloak_events import AdminEventRequest, KeycloakEventRequest
+from pyatlan.validate import validate_arguments
 
 
 class AsyncAdminClient:

pyatlan/client/aio/asset.py

@@ -18,8 +18,6 @@
 )
 
 from pydantic.v1 import StrictStr, constr
-
-from pyatlan.validate import validate_arguments
 from tenacity import (
     retry,
     retry_if_exception_type,
@@ -86,6 +84,7 @@
 from pyatlan.model.fields.atlan_fields import AtlanField
 from pyatlan.model.response import AssetMutationResponse
 from pyatlan.model.search import IndexSearchRequest, Query
+from pyatlan.validate import validate_arguments
 
 if TYPE_CHECKING:
     from pyatlan.model.search import IndexSearchRequest

pyatlan/client/aio/audit.py

@@ -4,12 +4,11 @@
 
 import logging
 
-from pyatlan.validate import validate_arguments
-
 from pyatlan.client.common import AsyncApiCaller, AuditSearch
 from pyatlan.errors import ErrorCode
 from pyatlan.model.aio.audit import AsyncAuditSearchResults
 from pyatlan.model.audit import AuditSearchRequest
+from pyatlan.validate import validate_arguments
 
 LOGGER = logging.getLogger(__name__)
 

pyatlan/client/aio/batch.py

@@ -4,8 +4,6 @@
 
 from typing import TYPE_CHECKING, Dict, List, Optional, cast
 
-from pyatlan.validate import _is_model_instance, validate_arguments
-
 from pyatlan.client.asset import (
     AssetCreationHandling,
     AssetIdentity,
@@ -17,6 +15,7 @@
 from pyatlan.model.fluent_search import FluentSearch
 from pyatlan.model.response import AssetMutationResponse
 from pyatlan.model.search import DSL
+from pyatlan.validate import _is_model_instance, validate_arguments
 
 if TYPE_CHECKING:
     from pyatlan.client.aio.client import AsyncAtlanClient

pyatlan/client/aio/client.py

@@ -57,6 +57,7 @@
     CONNECTION_RETRY,
     VERSION,
     AtlanClient,
+    _is_msgspec_struct,
     get_python_version,
 )
 from pyatlan.client.common import ImpersonateUser
@@ -488,6 +489,12 @@ async def _create_params(
                 params["data"] = await async_request.json()
             elif api.consumes == APPLICATION_ENCODED_FORM:
                 params["data"] = request_obj
+            elif _is_msgspec_struct(request_obj):
+                from pyatlan_v9.model.core import AtlanRequest as V9AtlanRequest
+
+                params["data"] = V9AtlanRequest(
+                    instance=request_obj, client=self
+                ).json()
             else:
                 params["data"] = json.dumps(request_obj)
         return params

pyatlan/client/aio/contract.py

@@ -4,12 +4,11 @@
 
 from typing import Optional
 
-from pyatlan.validate import validate_arguments
-
 from pyatlan.client.common import AsyncApiCaller, ContractInit
 from pyatlan.client.constants import CONTRACT_INIT_API
 from pyatlan.errors import ErrorCode
 from pyatlan.model.assets import Asset
+from pyatlan.validate import validate_arguments
 
 
 class AsyncContractClient:

pyatlan/client/aio/credential.py

@@ -4,8 +4,6 @@
 
 from typing import TYPE_CHECKING, Any, Dict, Optional
 
-from pyatlan.validate import validate_arguments
-
 from pyatlan.client.common import (
     AsyncApiCaller,
     CredentialCreate,
@@ -23,6 +21,7 @@
     CredentialResponse,
     CredentialTestResponse,
 )
+from pyatlan.validate import validate_arguments
 
 if TYPE_CHECKING:
     pass

pyatlan/client/aio/file.py

@@ -2,8 +2,6 @@
 # Copyright 2025 Atlan Pte. Ltd.
 from __future__ import annotations
 
-from pyatlan.validate import validate_arguments
-
 from pyatlan.client.common import (
     AsyncApiCaller,
     FileDownload,
@@ -12,6 +10,7 @@
 )
 from pyatlan.errors import ErrorCode
 from pyatlan.model.file import PresignedURLRequest
+from pyatlan.validate import validate_arguments
 
 
 class AsyncFileClient:

pyatlan/client/aio/group.py

@@ -6,8 +6,6 @@
 
 from pydantic.v1 import parse_obj_as
 
-from pyatlan.validate import validate_arguments
-
 from pyatlan.client.common import (
     AsyncApiCaller,
     GroupCreate,
@@ -22,6 +20,7 @@
 from pyatlan.model.aio.user import AsyncUserResponse
 from pyatlan.model.group import AtlanGroup, CreateGroupResponse
 from pyatlan.model.user import UserRequest
+from pyatlan.validate import validate_arguments
 
 
 class AsyncGroupClient: