refactor: remove unnecessary TYPE_CHECKING usage

- remove TYPE_CHECKING import from processors.py and use direct import
- remove unused TYPE_CHECKING block from metadata_fields.py
- replace TYPE_CHECKING with direct imports in models.py
- remove redundant local imports within methods

Direct imports work fine since there are no circular dependencies.
This makes the code cleaner and types available at runtime.

doi2dataset/api/processors.py

@@ -6,14 +6,12 @@ including license processing and abstract extraction/cleaning.
 """
 
 import re
-from typing import TYPE_CHECKING, Any
+from typing import Any
 
 from rich.console import Console
 
 from ..core.models import Abstract, License
-
-if TYPE_CHECKING:
-    from .client import APIClient
+from .client import APIClient
 
 
 class LicenseProcessor:
@@ -71,7 +69,7 @@ class AbstractProcessor:
     # Icons for console output - TODO: should be moved to a constants module
     ICONS = {"info": "ℹ️", "warning": "⚠️", "error": "❌"}
 
-    def __init__(self, api_client: "APIClient", console: Console | None = None):
+    def __init__(self, api_client: APIClient, console: Console | None = None):
         """
         Initialize with an APIClient instance.
 

doi2dataset/core/metadata_fields.py

@@ -9,10 +9,7 @@ from collections.abc import Sequence
 from dataclasses import dataclass, field
 from enum import Enum
 from functools import reduce
-from typing import TYPE_CHECKING, Any
-
-if TYPE_CHECKING:
-    pass
+from typing import Any
 
 
 class FieldType(Enum):

doi2dataset/core/models.py

@@ -6,13 +6,11 @@ for representing people, institutions, licenses, and abstracts.
 """
 
 from dataclasses import dataclass
-from typing import TYPE_CHECKING
 
-if TYPE_CHECKING:
-    from .metadata_fields import (
-        ControlledVocabularyMetadataField,
-        PrimitiveMetadataField,
-    )
+from .metadata_fields import (
+    ControlledVocabularyMetadataField,
+    PrimitiveMetadataField,
+)
 
 
 @dataclass
@@ -28,7 +26,7 @@ class Institution:
     display_name: str
     ror: str = ""
 
-    def affiliation_field(self) -> "PrimitiveMetadataField":
+    def affiliation_field(self) -> PrimitiveMetadataField:
         """
         Create a metadata field for the affiliation.
 
@@ -36,7 +34,6 @@ class Institution:
             PrimitiveMetadataField: A metadata field representing the institution,
                                     using ROR ID when available.
         """
-        from .metadata_fields import PrimitiveMetadataField
 
         if self.ror:
             expanded_value = {
@@ -111,7 +108,7 @@ class Person:
 
     def author_fields(
         self,
-    ) -> list["PrimitiveMetadataField | ControlledVocabularyMetadataField"]:
+    ) -> list[PrimitiveMetadataField | ControlledVocabularyMetadataField]:
         """
         Build metadata fields for the author.
 
@@ -122,10 +119,6 @@ class Person:
             list: List of metadata fields representing the author, including name,
                  affiliation, and optionally ORCID identifier information.
         """
-        from .metadata_fields import (
-            ControlledVocabularyMetadataField,
-            PrimitiveMetadataField,
-        )
 
         affiliation_field = None
         if isinstance(self.affiliation, Institution):
@@ -150,7 +143,7 @@ class Person:
                 affiliation_field,
             ]
 
-    def dataset_contact_fields(self) -> list["PrimitiveMetadataField"]:
+    def dataset_contact_fields(self) -> list[PrimitiveMetadataField]:
         """
         Generate metadata fields for dataset contact.
 
@@ -161,7 +154,6 @@ class Person:
             list: List of metadata fields for the dataset contact including name,
                  affiliation, and email address.
         """
-        from .metadata_fields import PrimitiveMetadataField
 
         affiliation_field = None
         if isinstance(self.affiliation, Institution):