fix(workflows): Don't return Workflows while they're being deleted (#112541)

Fixes ISWF-2420.

Author: kcons

src/sentry/api/bases/rule.py

@@ -62,7 +62,9 @@ def convert_args(
         if use_workflow_engine:
             try:
                 arw = AlertRuleWorkflow.objects.get(
-                    rule_id=rule_id, workflow__organization=project.organization
+                    rule_id=rule_id,
+                    workflow__organization=project.organization,
+                    workflow__status=ObjectStatus.ACTIVE,
                 )
                 kwargs["rule"] = arw.workflow
             except AlertRuleWorkflow.DoesNotExist:

src/sentry/api/endpoints/project_rule_details.py

@@ -451,6 +451,10 @@ def delete(self, request: Request, project: Project, rule: Rule | Workflow) -> R
                     rule=rule, user_id=request.user.id, type=RuleActivityType.DELETED.value
                 )
                 scheduled = CellScheduledDeletion.schedule(rule, days=0, actor=request.user)
+                # The Rule's scheduled deletion should take care of the workflow, but
+                # we mark it pending immediately so we don't return it while the deletion is in progress.
+                for workflow in Workflow.objects.filter(alertruleworkflow__rule_id=rule.id):
+                    workflow.update(status=ObjectStatus.PENDING_DELETION)
 
             self.create_audit_entry(
                 request=request,

tests/sentry/api/endpoints/test_project_rule_details.py

@@ -267,6 +267,16 @@ def test_workflow_engine_granular_flag_single_written_rule(self) -> None:
         assert response.data["conditions"][0]["name"]
         assert response.data["filters"][0]["name"]
 
+    @with_feature("organizations:workflow-engine-issue-alert-endpoints-get")
+    def test_deleted_dual_written_rule_returns_404(self) -> None:
+        rule = self.create_project_rule(self.project)
+        # DELETE schedules deletion but we intentionally do NOT run it
+        self.get_success_response(
+            self.organization.slug, rule.project.slug, rule.id, method="delete", status_code=202
+        )
+        # GET should 404 even though the scheduled deletion hasn't executed
+        self.get_error_response(self.organization.slug, rule.project.slug, rule.id, status_code=404)
+
     def test_non_existing_rule(self) -> None:
         self.get_error_response(self.organization.slug, self.project.slug, 12345, status_code=404)