5 files changed, 69 insertions, 9 deletions
diff --git a/app/graphql/mutations/work_items/create.rb b/app/graphql/mutations/work_items/create.rb
index c29dbb899b5..2e136d409ab 100644
--- a/app/graphql/mutations/work_items/create.rb
+++ b/app/graphql/mutations/work_items/create.rb
@@ -53,9 +53,6 @@ module Mutations
       private
 
       def global_id_compatibility_params(params)
-        # TODO: remove this line when the compatibility layer is removed
-        # See: https://gitlab.com/gitlab-org/gitlab/-/issues/257883
-        params[:work_item_type_id] = ::Types::GlobalIDType[::WorkItems::Type].coerce_isolated_input(params[:work_item_type_id]) if params[:work_item_type_id]
         params[:work_item_type_id] = params[:work_item_type_id]&.model_id
 
         params
diff --git a/app/graphql/mutations/work_items/create_from_task.rb b/app/graphql/mutations/work_items/create_from_task.rb
index 278c1bc65a9..4da709401a6 100644
--- a/app/graphql/mutations/work_items/create_from_task.rb
+++ b/app/graphql/mutations/work_items/create_from_task.rb
@@ -55,8 +55,6 @@ module Mutations
       private
 
       def find_object(id:)
-        # TODO: Remove coercion when working on https://gitlab.com/gitlab-org/gitlab/-/issues/257883
-        id = ::Types::GlobalIDType[::WorkItem].coerce_isolated_input(id)
         GitlabSchema.find_by_gid(id)
       end
     end
diff --git a/app/graphql/mutations/work_items/delete.rb b/app/graphql/mutations/work_items/delete.rb
index 3d72ebbd95d..1830ab5443c 100644
--- a/app/graphql/mutations/work_items/delete.rb
+++ b/app/graphql/mutations/work_items/delete.rb
@@ -38,8 +38,6 @@ module Mutations
       private
 
       def find_object(id:)
-        # TODO: Remove coercion when working on https://gitlab.com/gitlab-org/gitlab/-/issues/257883
-        id = ::Types::GlobalIDType[::WorkItem].coerce_isolated_input(id)
         GitlabSchema.find_by_gid(id)
       end
     end
diff --git a/app/graphql/mutations/work_items/delete_task.rb b/app/graphql/mutations/work_items/delete_task.rb
new file mode 100644
index 00000000000..87620a28fa1
--- /dev/null
+++ b/app/graphql/mutations/work_items/delete_task.rb
@@ -0,0 +1,69 @@
+# frozen_string_literal: true
+
+module Mutations
+  module WorkItems
+    class DeleteTask < BaseMutation
+      graphql_name 'WorkItemDeleteTask'
+
+      description "Deletes a task in a work item's description." \
+                  ' Available only when feature flag `work_items` is enabled. This feature is experimental and' \
+                  ' is subject to change without notice.'
+
+      authorize :update_work_item
+
+      argument :id, ::Types::GlobalIDType[::WorkItem],
+               required: true,
+               description: 'Global ID of the work item.'
+      argument :lock_version, GraphQL::Types::Int,
+               required: true,
+               description: 'Current lock version of the work item containing the task in the description.'
+      argument :task_data, ::Types::WorkItems::DeletedTaskInputType,
+               required: true,
+               description: 'Arguments necessary to delete a task from a work item\'s description.',
+               prepare: ->(attributes, _ctx) { attributes.to_h }
+
+      field :work_item, Types::WorkItemType,
+            null: true,
+            description: 'Updated work item.'
+
+      def resolve(id:, lock_version:, task_data:)
+        work_item = authorized_find!(id: id)
+        task_data[:task] = authorized_find_task!(task_data[:id])
+
+        unless work_item.project.work_items_feature_flag_enabled?
+          return { errors: ['`work_items` feature flag disabled for this project'] }
+        end
+
+        result = ::WorkItems::DeleteTaskService.new(
+          work_item: work_item,
+          current_user: current_user,
+          lock_version: lock_version,
+          task_params: task_data
+        ).execute
+
+        response = { errors: result.errors }
+        response[:work_item] = work_item if result.success?
+
+        response
+      end
+
+      private
+
+      def authorized_find_task!(task_id)
+        task = ::Gitlab::Graphql::Lazy.force(GitlabSchema.find_by_gid(task_id))
+
+        if current_user.can?(:delete_work_item, task)
+          task
+        else
+          # Fail early if user cannot delete task
+          raise_resource_not_available_error!
+        end
+      end
+
+      # method used by `authorized_find!(id: id)`
+      def find_object(id:)
+        GitlabSchema.find_by_gid(id)
+      end
+    end
+  end
+end
diff --git a/app/graphql/mutations/work_items/update.rb b/app/graphql/mutations/work_items/update.rb
index 091237d6fa0..20319301482 100644
--- a/app/graphql/mutations/work_items/update.rb
+++ b/app/graphql/mutations/work_items/update.rb
@@ -52,8 +52,6 @@ module Mutations
       private
 
       def find_object(id:)
-        # TODO: Remove coercion when working on https://gitlab.com/gitlab-org/gitlab/-/issues/257883
-        id = ::Types::GlobalIDType[::WorkItem].coerce_isolated_input(id)
         GitlabSchema.find_by_gid(id)
       end
     end