docs: BED-10188 API spec for get extension retention policy

packages/go/openapi/src/openapi.yaml

@@ -392,6 +392,8 @@ paths:
     $ref: './paths/graph.graphs.acl-inheritance.yaml'
   # /api/v2/graph-retention-policies/base/policy:
   #   $ref: './paths/graph-retention-policies.base.policy.yaml'
+  # /api/v2/graph-retention-policies/extensions/{extension_id}/policy:
+  #   $ref: './paths/graph-retention-policies.extensions.id.policy.yaml'
 
   # opengraph extensions
   /api/v2/extensions:

packages/go/openapi/src/paths/graph-retention-policies.extensions.id.policy.yaml

@@ -0,0 +1,53 @@
+# Copyright 2026 Specter Ops, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+parameters:
+  - $ref: './../parameters/header.prefer.yaml'
+  - name: extension_id
+    description: Extension ID
+    in: path
+    required: true
+    schema:
+      type: integer
+      format: int64
+get:
+  operationId: GetExtensionRetentionPolicy
+  summary: Get Extension Retention Policy
+  tags:
+    - Graph Retention Policies
+    - Enterprise
+  responses:
+    200:
+      description: OK
+      content:
+        application/json:
+          schema:
+            type: object
+            properties:
+              data:
+                $ref: './../schemas/model.graph-extension-retention-policy.yaml'
+    400:
+      $ref: './../responses/bad-request.yaml'
+    401:
+      $ref: './../responses/unauthorized.yaml'
+    403:
+      $ref: './../responses/forbidden.yaml'
+    404:
+      $ref: './../responses/not-found.yaml'
+    429:
+      $ref: './../responses/too-many-requests.yaml'
+    500:
+      $ref: './../responses/internal-server-error.yaml'

packages/go/openapi/src/schemas/model.graph-extension-retention-policy.yaml

@@ -0,0 +1,25 @@
+# Copyright 2026 Specter Ops, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+type: object
+description: The data to describe an extension retention policy
+allOf:
+  - $ref: './model.graph-retention-policy.yaml'
+  - type: object
+    properties:
+      extension_id:
+        type: integer
+