ref(workflow_engine): Route detector deletion through validators (#102919)

Adds delete() method to BaseDetectorTypeValidator to consolidate all
CRUD operations (create, update, delete) within validators. This allows
detector-specific logic to be cleanly overridden in subclass validators
and replaces the need for lifecycle hooks.

- Validators already handle create() and update() with access to old
state
  via self.instance
- Validators can raise ValidationError for user-facing errors (e.g.,
billing
  seat failures)
- Overriding delete() allows immediate actions when a user perceives
their
  detector as deleted (e.g., freeing billing seats, stopping checks)
- Additional async cleanup still happens via data source-specific
deletion
  tasks that the detector cascades into

The default implementation schedules the detector for deletion and
updates
its status. Subclasses can override to perform detector-specific cleanup
before calling super().delete().

Author: evanpurkhiser

src/sentry/workflow_engine/endpoints/organization_detector_details.py

@@ -20,9 +20,7 @@
     RESPONSE_UNAUTHORIZED,
 )
 from sentry.apidocs.parameters import DetectorParams, GlobalParams
-from sentry.constants import ObjectStatus
 from sentry.db.postgres.transactions import in_test_hide_transaction_boundary
-from sentry.deletions.models.scheduleddeletion import RegionScheduledDeletion
 from sentry.grouping.grouptype import ErrorGroupType
 from sentry.incidents.grouptype import MetricIssue
 from sentry.incidents.metric_issue_detector import schedule_update_project_config
@@ -202,8 +200,10 @@ def delete(self, request: Request, organization: Organization, detector: Detecto
         if detector.type == ErrorGroupType.slug:
             return Response(status=403)
 
-        RegionScheduledDeletion.schedule(detector, days=0, actor=request.user)
-        detector.update(status=ObjectStatus.PENDING_DELETION)
+        validator = get_detector_validator(
+            request, detector.project, detector.type, instance=detector
+        )
+        validator.delete()
 
         DetectorLifeCycleHooks.on_pending_delete(detector)
 

src/sentry/workflow_engine/endpoints/validators/base/detector.py

@@ -9,6 +9,8 @@
 from sentry import audit_log
 from sentry.api.fields.actor import ActorField
 from sentry.api.serializers.rest_framework import CamelSnakeSerializer
+from sentry.constants import ObjectStatus
+from sentry.deletions.models.scheduleddeletion import RegionScheduledDeletion
 from sentry.issues import grouptype
 from sentry.issues.grouptype import GroupType
 from sentry.utils.audit import create_audit_entry
@@ -144,6 +146,18 @@ def update(self, instance: Detector, validated_data: dict[str, Any]):
         DetectorLifeCycleHooks.on_after_update(instance)
         return instance
 
+    def delete(self) -> None:
+        """
+        Delete the detector by scheduling it for deletion.
+
+        Subclasses can override this to perform detector-specific cleanup before
+        deletion (e.g., removing billing seats, cleaning up external resources).
+        They should call super().delete() to perform the actual deletion.
+        """
+        assert self.instance is not None
+        RegionScheduledDeletion.schedule(self.instance, days=0, actor=self.context["request"].user)
+        self.instance.update(status=ObjectStatus.PENDING_DELETION)
+
     def _create_data_source(self, validated_data_source, detector: Detector):
         data_source_creator = validated_data_source["_creator"]
         data_source = data_source_creator.create()

tests/sentry/workflow_engine/endpoints/test_validators.py

@@ -5,6 +5,8 @@
 from rest_framework.exceptions import ErrorDetail, ValidationError
 
 from sentry import audit_log
+from sentry.constants import ObjectStatus
+from sentry.deletions.models.scheduleddeletion import RegionScheduledDeletion
 from sentry.incidents.grouptype import MetricIssue
 from sentry.incidents.metric_issue_detector import (
     MetricIssueComparisonConditionValidator,
@@ -247,3 +249,19 @@ def test_validate_type_incompatible(self) -> None:
             assert validator.errors.get("type") == [
                 ErrorDetail(string="Detector type not compatible with detectors", code="invalid")
             ]
+
+    def test_delete(self) -> None:
+        """Test that delete() schedules the detector for deletion"""
+        validator = MockDetectorValidator(data=self.valid_data, context=self.context)
+        assert validator.is_valid()
+        detector = validator.save()
+
+        delete_validator = MockDetectorValidator(instance=detector, data={}, context=self.context)
+        delete_validator.delete()
+
+        assert RegionScheduledDeletion.objects.filter(
+            model_name="Detector", object_id=detector.id
+        ).exists()
+
+        detector.refresh_from_db()
+        assert detector.status == ObjectStatus.PENDING_DELETION