diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 76587286..b298b664 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -19,7 +19,7 @@ jobs:
     runs-on: ${{ github.repository == 'stainless-sdks/imagekit-python' && 'depot-ubuntu-24.04' || 'ubuntu-latest' }}
     if: github.event_name == 'push' || github.event.pull_request.head.repo.fork
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Install Rye
         run: |
@@ -44,7 +44,7 @@ jobs:
       id-token: write
     runs-on: ${{ github.repository == 'stainless-sdks/imagekit-python' && 'depot-ubuntu-24.04' || 'ubuntu-latest' }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Install Rye
         run: |
@@ -81,7 +81,7 @@ jobs:
     runs-on: ${{ github.repository == 'stainless-sdks/imagekit-python' && 'depot-ubuntu-24.04' || 'ubuntu-latest' }}
     if: github.event_name == 'push' || github.event.pull_request.head.repo.fork
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Install Rye
         run: |
diff --git a/.github/workflows/publish-pypi.yml b/.github/workflows/publish-pypi.yml
index 08adafc8..446c7cfd 100644
--- a/.github/workflows/publish-pypi.yml
+++ b/.github/workflows/publish-pypi.yml
@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Install Rye
         run: |
diff --git a/.github/workflows/release-doctor.yml b/.github/workflows/release-doctor.yml
index c36a89df..27e5f93d 100644
--- a/.github/workflows/release-doctor.yml
+++ b/.github/workflows/release-doctor.yml
@@ -12,7 +12,7 @@ jobs:
     if: github.repository == 'imagekit-developer/imagekit-python' && (github.event_name == 'push' || github.event_name == 'workflow_dispatch' || startsWith(github.head_ref, 'release-please') || github.head_ref == 'next')
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Check release environment
         run: |
diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 4808d97d..473ec8bf 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "5.1.0"
+  ".": "5.1.1"
 }
\ No newline at end of file
diff --git a/.stats.yml b/.stats.yml
index 265ca1f6..1fdb990a 100644
--- a/.stats.yml
+++ b/.stats.yml
@@ -1,4 +1,4 @@
 configured_endpoints: 48
-openapi_spec_url: https://storage.googleapis.com/stainless-sdk-openapi-specs/imagekit-inc%2Fimagekit-c028a7584d3508f268ce5c5b824b50af88eaa140620dd03a1b35f409f510603c.yml
-openapi_spec_hash: f9b780b2398a87678a13355e48cd515f
+openapi_spec_url: https://storage.googleapis.com/stainless-sdk-openapi-specs/imagekit-inc%2Fimagekit-84f0d75048a9268981a84800b4190e3691997ce57dcfc0876f38a5b3fce6bacd.yml
+openapi_spec_hash: 35607d4e850c8a60524223ff632c83bb
 config_hash: aeb6eb949d73382270bbd8bbf2e4cf2a
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 11482046..4bdf7d59 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,18 @@
 # Changelog
 
+## 5.1.1 (2026-01-20)
+
+Full Changelog: [v5.1.0...v5.1.1](https://github.com/imagekit-developer/imagekit-python/compare/v5.1.0...v5.1.1)
+
+### Bug Fixes
+
+* vocab field is required ([4ab29b2](https://github.com/imagekit-developer/imagekit-python/commit/4ab29b248b89398b4334d6e1946a35a561997b2a))
+
+
+### Chores
+
+* **internal:** update `actions/checkout` version ([7826590](https://github.com/imagekit-developer/imagekit-python/commit/782659076636d78290d488da3f834343550627c8))
+
 ## 5.1.0 (2026-01-16)
 
 Full Changelog: [v5.0.0...v5.1.0](https://github.com/imagekit-developer/imagekit-python/compare/v5.0.0...v5.1.0)
diff --git a/pyproject.toml b/pyproject.toml
index 39ea40bd..81c13404 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "imagekitio"
-version = "5.1.0"
+version = "5.1.1"
 description = "The official Python library for the ImageKit API"
 dynamic = ["readme"]
 license = "Apache-2.0"
diff --git a/src/imagekitio/_version.py b/src/imagekitio/_version.py
index ed8df8a5..b2e2ff26 100644
--- a/src/imagekitio/_version.py
+++ b/src/imagekitio/_version.py
@@ -1,4 +1,4 @@
 # File generated from our OpenAPI spec by Stainless. See CONTRIBUTING.md for details.
 
 __title__ = "imagekitio"
-__version__ = "5.1.0"  # x-release-please-version
+__version__ = "5.1.1"  # x-release-please-version
diff --git a/src/imagekitio/types/shared/extension_config.py b/src/imagekitio/types/shared/extension_config.py
index 04ae44f1..5cc15e93 100644
--- a/src/imagekitio/types/shared/extension_config.py
+++ b/src/imagekitio/types/shared/extension_config.py
@@ -90,19 +90,19 @@ class AITasksTaskSelectTags(BaseModel):
     type: Literal["select_tags"]
     """Task type that analyzes the image and adds matching tags from a vocabulary."""
 
-    vocabulary: List[str]
-    """Array of possible tag values.
-
-    Combined length of all strings must not exceed 500 characters. Cannot contain
-    the `%` character.
-    """
-
     max_selections: Optional[int] = None
     """Maximum number of tags to select from the vocabulary."""
 
     min_selections: Optional[int] = None
     """Minimum number of tags to select from the vocabulary."""
 
+    vocabulary: Optional[List[str]] = None
+    """Array of possible tag values.
+
+    Combined length of all strings must not exceed 500 characters. Cannot contain
+    the `%` character.
+    """
+
 
 class AITasksTaskSelectMetadata(BaseModel):
     field: str
diff --git a/src/imagekitio/types/shared/extensions.py b/src/imagekitio/types/shared/extensions.py
index f061a94c..94f132c8 100644
--- a/src/imagekitio/types/shared/extensions.py
+++ b/src/imagekitio/types/shared/extensions.py
@@ -92,19 +92,19 @@ class ExtensionItemAITasksTaskSelectTags(BaseModel):
     type: Literal["select_tags"]
     """Task type that analyzes the image and adds matching tags from a vocabulary."""
 
-    vocabulary: List[str]
-    """Array of possible tag values.
-
-    Combined length of all strings must not exceed 500 characters. Cannot contain
-    the `%` character.
-    """
-
     max_selections: Optional[int] = None
     """Maximum number of tags to select from the vocabulary."""
 
     min_selections: Optional[int] = None
     """Minimum number of tags to select from the vocabulary."""
 
+    vocabulary: Optional[List[str]] = None
+    """Array of possible tag values.
+
+    Combined length of all strings must not exceed 500 characters. Cannot contain
+    the `%` character.
+    """
+
 
 class ExtensionItemAITasksTaskSelectMetadata(BaseModel):
     field: str
diff --git a/src/imagekitio/types/shared_params/extension_config.py b/src/imagekitio/types/shared_params/extension_config.py
index b582a6c2..453fb735 100644
--- a/src/imagekitio/types/shared_params/extension_config.py
+++ b/src/imagekitio/types/shared_params/extension_config.py
@@ -90,19 +90,19 @@ class AITasksTaskSelectTags(TypedDict, total=False):
     type: Required[Literal["select_tags"]]
     """Task type that analyzes the image and adds matching tags from a vocabulary."""
 
-    vocabulary: Required[SequenceNotStr[str]]
-    """Array of possible tag values.
-
-    Combined length of all strings must not exceed 500 characters. Cannot contain
-    the `%` character.
-    """
-
     max_selections: int
     """Maximum number of tags to select from the vocabulary."""
 
     min_selections: int
     """Minimum number of tags to select from the vocabulary."""
 
+    vocabulary: SequenceNotStr[str]
+    """Array of possible tag values.
+
+    Combined length of all strings must not exceed 500 characters. Cannot contain
+    the `%` character.
+    """
+
 
 class AITasksTaskSelectMetadata(TypedDict, total=False):
     field: Required[str]
diff --git a/src/imagekitio/types/shared_params/extensions.py b/src/imagekitio/types/shared_params/extensions.py
index 02858543..f4c81491 100644
--- a/src/imagekitio/types/shared_params/extensions.py
+++ b/src/imagekitio/types/shared_params/extensions.py
@@ -92,19 +92,19 @@ class ExtensionItemAITasksTaskSelectTags(TypedDict, total=False):
     type: Required[Literal["select_tags"]]
     """Task type that analyzes the image and adds matching tags from a vocabulary."""
 
-    vocabulary: Required[SequenceNotStr[str]]
-    """Array of possible tag values.
-
-    Combined length of all strings must not exceed 500 characters. Cannot contain
-    the `%` character.
-    """
-
     max_selections: int
     """Maximum number of tags to select from the vocabulary."""
 
     min_selections: int
     """Minimum number of tags to select from the vocabulary."""
 
+    vocabulary: SequenceNotStr[str]
+    """Array of possible tag values.
+
+    Combined length of all strings must not exceed 500 characters. Cannot contain
+    the `%` character.
+    """
+
 
 class ExtensionItemAITasksTaskSelectMetadata(TypedDict, total=False):
     field: Required[str]
diff --git a/tests/api_resources/beta/v2/test_files.py b/tests/api_resources/beta/v2/test_files.py
index 391e3694..fdeae5ab 100644
--- a/tests/api_resources/beta/v2/test_files.py
+++ b/tests/api_resources/beta/v2/test_files.py
@@ -62,9 +62,9 @@ def test_method_upload_with_all_params(self, client: ImageKit) -> None:
                         {
                             "instruction": "What types of clothing items are visible in this image?",
                             "type": "select_tags",
-                            "vocabulary": ["shirt", "tshirt", "dress", "trousers", "jacket"],
                             "max_selections": 1,
                             "min_selections": 0,
+                            "vocabulary": ["shirt", "tshirt", "dress", "trousers", "jacket"],
                         },
                         {
                             "instruction": "Is this a luxury or high-end fashion item?",
@@ -217,9 +217,9 @@ async def test_method_upload_with_all_params(self, async_client: AsyncImageKit)
                         {
                             "instruction": "What types of clothing items are visible in this image?",
                             "type": "select_tags",
-                            "vocabulary": ["shirt", "tshirt", "dress", "trousers", "jacket"],
                             "max_selections": 1,
                             "min_selections": 0,
+                            "vocabulary": ["shirt", "tshirt", "dress", "trousers", "jacket"],
                         },
                         {
                             "instruction": "Is this a luxury or high-end fashion item?",
diff --git a/tests/api_resources/test_dummy.py b/tests/api_resources/test_dummy.py
index 74f515a0..8d6dd188 100644
--- a/tests/api_resources/test_dummy.py
+++ b/tests/api_resources/test_dummy.py
@@ -70,9 +70,9 @@ def test_method_create_with_all_params(self, client: ImageKit) -> None:
                         {
                             "instruction": "What types of clothing items are visible in this image?",
                             "type": "select_tags",
-                            "vocabulary": ["shirt", "tshirt", "dress", "trousers", "jacket"],
                             "max_selections": 1,
                             "min_selections": 0,
+                            "vocabulary": ["shirt", "tshirt", "dress", "trousers", "jacket"],
                         },
                         {
                             "instruction": "Is this a luxury or high-end fashion item?",
@@ -887,9 +887,9 @@ async def test_method_create_with_all_params(self, async_client: AsyncImageKit)
                         {
                             "instruction": "What types of clothing items are visible in this image?",
                             "type": "select_tags",
-                            "vocabulary": ["shirt", "tshirt", "dress", "trousers", "jacket"],
                             "max_selections": 1,
                             "min_selections": 0,
+                            "vocabulary": ["shirt", "tshirt", "dress", "trousers", "jacket"],
                         },
                         {
                             "instruction": "Is this a luxury or high-end fashion item?",
diff --git a/tests/api_resources/test_files.py b/tests/api_resources/test_files.py
index c9aa9cdf..c41be9b2 100644
--- a/tests/api_resources/test_files.py
+++ b/tests/api_resources/test_files.py
@@ -62,9 +62,9 @@ def test_method_update_with_all_params_overload_1(self, client: ImageKit) -> Non
                         {
                             "instruction": "What types of clothing items are visible in this image?",
                             "type": "select_tags",
-                            "vocabulary": ["shirt", "tshirt", "dress", "trousers", "jacket"],
                             "max_selections": 1,
                             "min_selections": 0,
+                            "vocabulary": ["shirt", "tshirt", "dress", "trousers", "jacket"],
                         },
                         {
                             "instruction": "Is this a luxury or high-end fashion item?",
@@ -465,9 +465,9 @@ def test_method_upload_with_all_params(self, client: ImageKit) -> None:
                         {
                             "instruction": "What types of clothing items are visible in this image?",
                             "type": "select_tags",
-                            "vocabulary": ["shirt", "tshirt", "dress", "trousers", "jacket"],
                             "max_selections": 1,
                             "min_selections": 0,
+                            "vocabulary": ["shirt", "tshirt", "dress", "trousers", "jacket"],
                         },
                         {
                             "instruction": "Is this a luxury or high-end fashion item?",
@@ -615,9 +615,9 @@ async def test_method_update_with_all_params_overload_1(self, async_client: Asyn
                         {
                             "instruction": "What types of clothing items are visible in this image?",
                             "type": "select_tags",
-                            "vocabulary": ["shirt", "tshirt", "dress", "trousers", "jacket"],
                             "max_selections": 1,
                             "min_selections": 0,
+                            "vocabulary": ["shirt", "tshirt", "dress", "trousers", "jacket"],
                         },
                         {
                             "instruction": "Is this a luxury or high-end fashion item?",
@@ -1018,9 +1018,9 @@ async def test_method_upload_with_all_params(self, async_client: AsyncImageKit)
                         {
                             "instruction": "What types of clothing items are visible in this image?",
                             "type": "select_tags",
-                            "vocabulary": ["shirt", "tshirt", "dress", "trousers", "jacket"],
                             "max_selections": 1,
                             "min_selections": 0,
+                            "vocabulary": ["shirt", "tshirt", "dress", "trousers", "jacket"],
                         },
                         {
                             "instruction": "Is this a luxury or high-end fashion item?",