diff --git a/README.md b/README.md
index 2b86479..6e60d5d 100644
--- a/README.md
+++ b/README.md
@@ -1,17 +1,19 @@
 # Gitea dynamic runner
 
-为 Gitea Actions 按需创建一次性执行环境。对 workflow 提供两种稳定的 runner
-接口：
+为 Gitea Actions 按需创建一次性执行环境。workflow 分别声明 workload class 与
+placement driver：
 
 ```yaml
-runs-on: [self-hosted, pod]
+runs-on: [self-hosted, container, kubernetes]
 ```
 
 ```yaml
-runs-on: [self-hosted, vm]
+runs-on: [self-hosted, vm, opensandbox]
 ```
 
-`pod` 使用动态 Kubernetes Pod，`vm` 使用动态 Cloud Hypervisor microVM。每个环境
+兼容标签 `[self-hosted, pod]` 严格映射为 `container+kubernetes`，
+`[self-hosted, vm]` 和 `vm-dev` 严格映射为 `vm+opensandbox`；显式 driver 容量耗尽时
+不会回退到其他 driver。每个环境
 只执行一个 job，并在 job 结束后连同本地状态一起销毁。完整的设计约束见
 [`docs/design-principles.md`](docs/design-principles.md)。
 
@@ -24,8 +26,8 @@ runs-on: [self-hosted, vm]
 - `scheduler`：以常驻 Gitea RunnerService 身份直接领取 task，并把完整 assignment
   持久化到 JetStream；一个 registration 下按配置启动多个并发 `FetchTask` goroutine，
   同时提供仅允许 SPIFFE mTLS 的 RunnerService facade。
-- `pod-worker`：直接在 homelab Kubernetes 创建一次性 Pod。
-- `vm-worker`：通过 OpenSandbox Lifecycle API 从 `ci-vm` Pool 创建 Kata microVM。
+- `kubernetes-worker`：直接在 homelab Kubernetes 创建一次性 container workload。
+- `opensandbox-worker`：通过 OpenSandbox Lifecycle API 从 `ci-vm` Pool 创建 VM workload。
 - 三个组件默认在同一个 Go 进程启用。首轮集成期间不允许只启动 worker，因为 facade
   的 assignment claim registry 仍是进程内状态；支持安全拆分前进程会明确拒绝该配置。
 - `microvm-runner-launch`：为每个任务以 direct I/O 转换出 flat qcow2 root disk、创建 NoCloud seed 和 TAP，运行
@@ -42,8 +44,8 @@ runs-on: [self-hosted, vm]
 - `jwt-broker`：早期共享 Kubernetes runner 的过渡实验；目标架构不部署它，每个
   动态 Pod 或 VM 直接取得自己的 SPIFFE 身份。
 
-Pod 路径由 homelab 集群中的 `pod-worker` 直接创建 Kubernetes Pod。OpenSandbox 只用于
-VM/Kata workload；两个 backend 使用独立 durable consumer 和独立容量池。assignment 根据
+Container/Kubernetes 路径由 homelab 集群中的 `kubernetes-worker` 直接创建 Pod。
+OpenSandbox 只用于 VM/Kata workload；每个 placement 使用独立 durable consumer 和容量池。assignment 根据
 `runs-on` 进入对应池，池满时留在 JetStream pending，不会创建超出容量的 workload；任一
 执行层故障不会阻塞另一条部署。长期 RunnerService 协议路线见
 [`docs/runner-protocol-roadmap.md`](docs/runner-protocol-roadmap.md)。
@@ -70,12 +72,13 @@ credential 都从挂载文件读取，不接受明文环境变量：
 - `NATS_PRODUCER_PASSWORD_FILE`、`NATS_WORKER_PASSWORD_FILE`：分别使用现有最小权限的
   `ci-producer` publish 连接和 `ci-worker` pull/ACK 连接，controller 不合并权限。
 - `RUNNER_FACADE_CAPABILITY_KEY_FILE`：至少 32 字节的 controller HMAC key。
-- `OPENSANDBOX_API_KEY_FILE`：仅启用 `vm-worker` 时读取。
+- `OPENSANDBOX_API_KEY_FILE`：仅启用 `opensandbox-worker` 时读取。
 
 必要的非 secret 配置包括 `POD_EXECUTOR_IMAGE`（应使用 digest）、`SPIRE_AGENT_ID`、
 `RUNNER_FACADE_URL`、`RUNNER_FACADE_SPIFFE_ID` 和 `SPIFFE_ENDPOINT_SOCKET`。默认
 `COMPONENTS=all`、Pod 并发 4、VM 并发 1；首次 smoke test 应显式设为
-`COMPONENTS=scheduler,pod-worker`，先验证 Pod 链路，避免同时消耗 VM 容量。
+`COMPONENTS=scheduler,kubernetes-worker`，先验证 Kubernetes 链路，避免同时消耗 VM
+容量。旧组件名 `pod-worker`、`vm-worker` 只作为配置兼容别名保留。
 
 Pod task 的 terminal update 被 Gitea 接受后，controller 会在 Pod 上持久写入
 `ci.ddupan.top/terminal=true` label。生命周期 reconciler 只清理同时带该 label 且已经
diff --git a/cmd/gitea-dynamic-runner/controller.go b/cmd/gitea-dynamic-runner/controller.go
index 0d753f4..334b998 100644
--- a/cmd/gitea-dynamic-runner/controller.go
+++ b/cmd/gitea-dynamic-runner/controller.go
@@ -38,6 +38,15 @@ type runComponent func(context.Context) error
 
 func (function runComponent) Run(ctx context.Context) error { return function(ctx) }
 
+type terminalBackend interface {
+	MarkTerminal(context.Context, string) error
+}
+
+type placementRuntime struct {
+	backend terminalBackend
+	pool    *backendpool.Pool
+}
+
 type controllerConfig struct {
 	Components                                                          controller.Selection
 	TrustDomain, WorkloadAPIAddr                                        string
@@ -61,7 +70,7 @@ func runController(ctx context.Context) error {
 	if !slices.Contains(config.Components, controller.Scheduler) {
 		return errors.New("split worker deployment is not yet safe: scheduler/facade must be enabled with workers")
 	}
-	if !slices.Contains(config.Components, controller.PodWorker) && !slices.Contains(config.Components, controller.VMWorker) {
+	if !slices.Contains(config.Components, controller.KubernetesWorker) && !slices.Contains(config.Components, controller.OpenSandboxWorker) {
 		return errors.New("scheduler requires at least one local backend worker")
 	}
 
@@ -92,32 +101,19 @@ func runController(ctx context.Context) error {
 		return err
 	}
 	registry := runnerfacade.NewRegistry()
-	podPool := backendpool.New(config.PodCapacity)
-	vmPool := backendpool.New(config.VMCapacity)
-	var podExecutorBackend *podbackend.Backend
-	var vmExecutorBackend *opensandboxbackend.Backend
+	runtimes := make(map[taskassignment.Placement]placementRuntime)
 	giteaClient := giteaactions.NewClient(giteaactions.DefaultHTTPClient(), config.GiteaURL, config.GiteaUUID, config.GiteaToken)
 	facade := &runnerfacade.Facade{
 		Registry: registry, Capabilities: capabilities, Upstream: giteaClient,
 		OnTerminal: func(ctx context.Context, assignment taskassignment.Assignment) error {
-			switch assignment.Backend {
-			case taskassignment.BackendPod:
-				if podExecutorBackend == nil {
-					return errors.New("Pod lifecycle backend is not configured")
-				}
-				if err := podExecutorBackend.MarkTerminal(ctx, assignment.ID); err != nil {
-					return err
-				}
-				podPool.Release(assignment.ID)
-			case taskassignment.BackendVM:
-				if vmExecutorBackend == nil {
-					return errors.New("VM lifecycle backend is not configured")
-				}
-				if err := vmExecutorBackend.MarkTerminal(ctx, assignment.ID); err != nil {
-					return err
-				}
-				vmPool.Release(assignment.ID)
+			runtime, ok := runtimes[assignment.Placement]
+			if !ok {
+				return fmt.Errorf("placement runtime %s is not configured", assignment.Placement.Key())
 			}
+			if err := runtime.backend.MarkTerminal(ctx, assignment.ID); err != nil {
+				return err
+			}
+			runtime.pool.Release(assignment.ID)
 			return nil
 		},
 	}
@@ -127,11 +123,11 @@ func runController(ctx context.Context) error {
 	}
 
 	labels := []string{"self-hosted"}
-	if slices.Contains(config.Components, controller.PodWorker) {
-		labels = append(labels, string(taskassignment.BackendPod))
+	if slices.Contains(config.Components, controller.KubernetesWorker) {
+		labels = append(labels, "pod", string(taskassignment.WorkloadContainer), string(taskassignment.DriverKubernetes))
 	}
-	if slices.Contains(config.Components, controller.VMWorker) {
-		labels = append(labels, config.VMRunnerLabel)
+	if slices.Contains(config.Components, controller.OpenSandboxWorker) {
+		labels = append(labels, config.VMRunnerLabel, string(taskassignment.DriverOpenSandbox))
 	}
 	poller := taskscheduler.Poller{
 		Client: giteaClient,
@@ -168,7 +164,9 @@ func runController(ctx context.Context) error {
 		}),
 	}
 
-	if slices.Contains(config.Components, controller.PodWorker) {
+	if slices.Contains(config.Components, controller.KubernetesWorker) {
+		placement := taskassignment.KubernetesContainer
+		pool := backendpool.New(config.PodCapacity)
 		client, err := podbackend.NewInClusterClient()
 		if err != nil {
 			return err
@@ -179,57 +177,59 @@ func runController(ctx context.Context) error {
 			SPIRECluster: config.SPIRECluster, SPIREClass: config.SPIREClass,
 			SPIREAgentID: config.SPIREAgentID, ExecutorUID: config.PodExecutorUID,
 		}}
-		podExecutorBackend = &backend
+		runtimes[placement] = placementRuntime{backend: backend, pool: pool}
 		assignments, err := backend.RecoverAssignments(ctx)
 		if err != nil {
 			return err
 		}
 		for _, assignment := range assignments {
-			podPool.Restore(assignment.ID)
+			pool.Restore(assignment.ID)
 			if err := registry.RecoverClaimed(assignment); err != nil {
 				return fmt.Errorf("recover Pod facade claim %s: %w", assignment.ID, err)
 			}
 		}
-		component, err := workerComponent(ctx, workerJS, config, taskassignment.BackendPod, config.PodCapacity, taskworker.Worker{Backend: backend, Bootstrap: bootstrap, OnEvent: workerEventLogger(taskassignment.BackendPod)}, registry, podPool)
+		component, err := workerComponent(ctx, workerJS, config, placement, config.PodCapacity, taskworker.Worker{Backend: backend, Bootstrap: bootstrap, OnEvent: workerEventLogger(placement)}, registry, pool)
 		if err != nil {
 			return err
 		}
 		lifecycle := podbackend.Lifecycle{Backend: backend, OnError: func(err error) {
-			slog.Error("backend lifecycle error", "component", "lifecycle", "backend", taskassignment.BackendPod, "error", err)
+			slog.Error("backend lifecycle error", "component", "lifecycle", "placement", placement.Key(), "error", err)
 		}}
-		components[controller.PodWorker] = runComponent(func(ctx context.Context) error {
+		components[controller.KubernetesWorker] = runComponent(func(ctx context.Context) error {
 			group, groupContext := errgroup.WithContext(ctx)
 			group.Go(func() error { return component.Run(groupContext) })
 			group.Go(func() error { return lifecycle.Run(groupContext) })
 			return group.Wait()
 		})
 	}
-	if slices.Contains(config.Components, controller.VMWorker) {
+	if slices.Contains(config.Components, controller.OpenSandboxWorker) {
+		placement := taskassignment.OpenSandboxVM
+		pool := backendpool.New(config.VMCapacity)
 		lifecycle := opensandboxbackend.NewLifecycleClient(config.OpenSandboxURL, config.OpenSandboxAPIKey, &http.Client{Timeout: 60 * time.Second})
 		backend := opensandboxbackend.Backend{Lifecycle: lifecycle, Config: opensandboxbackend.Config{
 			Pool: config.OpenSandboxPool, Timeout: config.VMTimeout,
 			Entrypoint: []string{"/usr/local/bin/gitea-dynamic-runner", "executor"},
 			Env:        map[string]string{"SPIFFE_ENDPOINT_SOCKET": config.WorkloadAPIAddr},
 		}}
-		vmExecutorBackend = &backend
+		runtimes[placement] = placementRuntime{backend: backend, pool: pool}
 		assignments, err := backend.RecoverAssignments(ctx, config.TrustDomain)
 		if err != nil {
 			return err
 		}
 		for _, assignment := range assignments {
-			vmPool.Restore(assignment.ID)
+			pool.Restore(assignment.ID)
 			if err := registry.RecoverClaimed(assignment); err != nil {
 				return fmt.Errorf("recover VM facade claim %s: %w", assignment.ID, err)
 			}
 		}
-		component, err := workerComponent(ctx, workerJS, config, taskassignment.BackendVM, config.VMCapacity, taskworker.Worker{Backend: backend, Bootstrap: bootstrap, OnEvent: workerEventLogger(taskassignment.BackendVM)}, registry, vmPool)
+		component, err := workerComponent(ctx, workerJS, config, placement, config.VMCapacity, taskworker.Worker{Backend: backend, Bootstrap: bootstrap, OnEvent: workerEventLogger(placement)}, registry, pool)
 		if err != nil {
 			return err
 		}
 		lifecycleReconciler := opensandboxbackend.LifecycleReconciler{Backend: backend, OnError: func(err error) {
-			slog.Error("backend lifecycle error", "component", "lifecycle", "backend", taskassignment.BackendVM, "error", err)
+			slog.Error("backend lifecycle error", "component", "lifecycle", "placement", placement.Key(), "error", err)
 		}}
-		components[controller.VMWorker] = runComponent(func(ctx context.Context) error {
+		components[controller.OpenSandboxWorker] = runComponent(func(ctx context.Context) error {
 			group, groupContext := errgroup.WithContext(ctx)
 			group.Go(func() error { return component.Run(groupContext) })
 			group.Go(func() error { return lifecycleReconciler.Run(groupContext) })
@@ -291,25 +291,25 @@ func connectNATS(server, user, password, caFile, clientName string) (*nats.Conn,
 	return nats.Connect(server, options...)
 }
 
-func workerComponent(ctx context.Context, js jetstream.JetStream, config controllerConfig, backend taskassignment.Backend, capacity int, accepter assignmentqueue.Accepter, claims assignmentqueue.Claims, admission assignmentqueue.Admission) (controller.Component, error) {
-	consumer, err := assignmentqueue.OpenConsumer(ctx, js, config.Stream, config.SubjectBase, backend, capacity)
+func workerComponent(ctx context.Context, js jetstream.JetStream, config controllerConfig, placement taskassignment.Placement, capacity int, accepter assignmentqueue.Accepter, claims assignmentqueue.Claims, admission assignmentqueue.Admission) (controller.Component, error) {
+	consumer, err := assignmentqueue.OpenConsumer(ctx, js, config.Stream, config.SubjectBase, placement, capacity)
 	if err != nil {
 		return nil, err
 	}
 	return assignmentqueue.ConsumerComponent{
 		Consumer: consumer, Capacity: capacity,
 		Processor: assignmentqueue.Processor{TrustDomain: config.TrustDomain, Accepter: accepter, Claims: claims, Admission: admission, OnEvent: func(event assignmentqueue.Event) {
-			slog.Info("assignment transition", "component", "worker", "event", event.Name, "backend", event.Backend, "assignment", event.AssignmentID, "retry_delay", event.RetryDelay)
+			slog.Info("assignment transition", "component", "worker", "event", event.Name, "placement", event.Placement.Key(), "assignment", event.AssignmentID, "retry_delay", event.RetryDelay)
 		}},
 		OnError: func(err error) {
-			slog.Error("assignment processing error", "component", "worker", "backend", backend, "error", err)
+			slog.Error("assignment processing error", "component", "worker", "placement", placement.Key(), "error", err)
 		},
 	}, nil
 }
 
-func workerEventLogger(backend taskassignment.Backend) func(taskworker.Event) {
+func workerEventLogger(placement taskassignment.Placement) func(taskworker.Event) {
 	return func(event taskworker.Event) {
-		slog.Info("executor transition", "component", "worker", "event", event.Name, "backend", backend, "assignment", event.AssignmentID, "executor", event.Executor, "phase", event.Phase)
+		slog.Info("executor transition", "component", "worker", "event", event.Name, "placement", placement.Key(), "assignment", event.AssignmentID, "executor", event.Executor, "phase", event.Phase)
 	}
 }
 
@@ -364,18 +364,18 @@ func loadControllerConfig() (controllerConfig, error) {
 	if config.WorkloadAPIAddr == "" || config.FacadeURL == "" || config.FacadeSPIFFEID == "" {
 		return controllerConfig{}, errors.New("SPIFFE_ENDPOINT_SOCKET, RUNNER_FACADE_URL, and RUNNER_FACADE_SPIFFE_ID are required")
 	}
-	if slices.Contains(selection, controller.PodWorker) && config.PodImage == "" {
-		return controllerConfig{}, errors.New("POD_EXECUTOR_IMAGE is required for pod-worker")
+	if slices.Contains(selection, controller.KubernetesWorker) && config.PodImage == "" {
+		return controllerConfig{}, errors.New("POD_EXECUTOR_IMAGE is required for kubernetes-worker")
 	}
-	if slices.Contains(selection, controller.PodWorker) && config.SPIREAgentID == "" {
-		return controllerConfig{}, errors.New("SPIRE_AGENT_ID is required for pod-worker")
+	if slices.Contains(selection, controller.KubernetesWorker) && config.SPIREAgentID == "" {
+		return controllerConfig{}, errors.New("SPIRE_AGENT_ID is required for kubernetes-worker")
 	}
-	if slices.Contains(selection, controller.VMWorker) {
+	if slices.Contains(selection, controller.OpenSandboxWorker) {
 		if config.VMRunnerLabel != "vm" && config.VMRunnerLabel != "vm-dev" {
 			return controllerConfig{}, errors.New("VM_RUNNER_LABEL must be vm or vm-dev")
 		}
 		if config.OpenSandboxURL == "" {
-			return controllerConfig{}, errors.New("OPENSANDBOX_API is required for vm-worker")
+			return controllerConfig{}, errors.New("OPENSANDBOX_API is required for opensandbox-worker")
 		}
 		config.OpenSandboxAPIKey, err = read("OPENSANDBOX_API_KEY_FILE")
 		if err != nil {
diff --git a/cmd/gitea-dynamic-runner/controller_test.go b/cmd/gitea-dynamic-runner/controller_test.go
index 0566001..a3ba373 100644
--- a/cmd/gitea-dynamic-runner/controller_test.go
+++ b/cmd/gitea-dynamic-runner/controller_test.go
@@ -34,7 +34,7 @@ func TestLoadControllerConfigUsesFileSecrets(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if len(config.Components) != 2 || config.Components[0] != controller.Scheduler || config.Components[1] != controller.PodWorker {
+	if len(config.Components) != 2 || config.Components[0] != controller.Scheduler || config.Components[1] != controller.KubernetesWorker {
 		t.Fatalf("components = %#v", config.Components)
 	}
 	if config.GiteaUUID != "scheduler-uuid" || config.GiteaToken != "scheduler-token" || config.NATSProducerPassword != "producer-password" || config.NATSWorkerPassword != "worker-password" {
diff --git a/docs/design-principles.md b/docs/design-principles.md
index 3f87fe8..d0122d1 100644
--- a/docs/design-principles.md
+++ b/docs/design-principles.md
@@ -2,19 +2,22 @@
 
 ## 对 workflow 的接口
 
-Runner 只向 workflow 暴露两个执行环境：
+Runner 将执行环境的能力类型与实现 driver 分开声明：
 
 ```yaml
-runs-on: [self-hosted, pod]
+runs-on: [self-hosted, container, kubernetes]
 ```
 
 ```yaml
-runs-on: [self-hosted, vm]
+runs-on: [self-hosted, vm, opensandbox]
 ```
 
 - `self-hosted` 是固定前缀。
-- `pod` 表示一次性 Kubernetes Pod，承担常规 CI、镜像构建和 kind 等任务。
-- `vm` 表示一次性 microVM，承担需要独立内核、KVM、systemd 或更强隔离的任务。
+- `container`、`vm` 是 workload class；`kubernetes`、`opensandbox` 是 placement driver。
+- 当前支持 `container+kubernetes` 和 `vm+opensandbox`。旧 `pod` 与 `vm` 标签分别是
+  两个组合的严格兼容别名，显式指定 driver 后不得因容量或故障回退到另一 driver。
+- container 承担常规 CI、镜像构建和 kind 等任务；VM 承担需要独立内核、KVM、
+  systemd 或更强隔离的任务。
 
 执行后端是基础设施选择，不是权限角色。workflow 不需要额外声明由 controller
 维护的 role 或权限 label。
diff --git a/docs/runner-protocol-roadmap.md b/docs/runner-protocol-roadmap.md
index f193c8c..9e66532 100644
--- a/docs/runner-protocol-roadmap.md
+++ b/docs/runner-protocol-roadmap.md
@@ -3,9 +3,9 @@
 ## 目标
 
 长期形态不依赖 `workflow_job` webhook 发现工作。controller 本身作为 Gitea Runner
-协议客户端注册，并声明 `self-hosted`、`pod` 和 `vm` labels；单个 registration 内按总
-配置容量启动多个 `FetchTask` goroutine，再将 task 按 `runs-on` 交给 Pod 或 VM 的独立
-容量池，由一次性 Pod 或 microVM 执行。
+协议客户端注册，并声明 workload class 与 driver labels；单个 registration 内按总
+配置容量启动多个 `FetchTask` goroutine，再将 task 按 `runs-on` 交给 placement 对应的
+独立容量池，由一次性 Pod 或 microVM 执行。
 
 ```text
 Gitea RunnerService
@@ -13,14 +13,14 @@ Gitea RunnerService
         ▼
 dynamic-runner scheduler
         │ 已领取的 task + lease
-        ├── Pod executor
-        └── microVM executor
+        ├── container.kubernetes executor
+        └── vm.opensandbox executor
                 │ logs / state / result
                 └──────────────────────► Gitea
 ```
 
-controller 使用单一 Go 二进制；默认在同一进程启用 `scheduler`、`pod-worker` 和
-`vm-worker`，也可通过 `--components` 只启用其中一部分。组件是独立应用服务边界，
+controller 使用单一 Go 二进制；默认在同一进程启用 `scheduler`、`kubernetes-worker`
+和 `opensandbox-worker`，也可通过 `--components` 只启用其中一部分。组件是独立应用服务边界，
 共享进程不意味着共享后端状态或把 assignment 降级为内存 channel。
 
 首轮集成的 facade pending/claimed registry 与三个组件同进程。虽然二进制保留组件选择
@@ -47,10 +47,13 @@ facade，并严格校验 facade 的 SPIFFE ID。这样无需修改 runner 或把
 
 ## 设计约束
 
-- 对 workflow 的接口保持 `[self-hosted, pod]` 和 `[self-hosted, vm]` 不变。
+- 规范接口为 `[self-hosted, container, kubernetes]` 和
+  `[self-hosted, vm, opensandbox]`。旧 `pod`、`vm`、`vm-dev` 标签保留严格映射，不能与
+  冲突 class/driver 混用；显式 driver 不允许自动回退。
 - scheduler 使用单一 Gitea runner UUID/token 和一个 `Declare`，不为并发槽位重复注册；
   `POD_CAPACITY + VM_CAPACITY` 决定并发 `FetchTask` goroutine 数量。
-- task 领取并持久化后按 backend 进入独立 durable consumer；对应容量池已满时延迟 NAK，
+- task 领取并持久化后按 placement 进入独立 durable consumer；v2 subject 为
+  `<subject-base>.<workload-class>.<driver>`。对应容量池已满时延迟 NAK，
   assignment 保持 JetStream pending，且不得创建超出配置容量的 workload。
 - scheduler Declare 后使用 RunnerService 长轮询；一旦 FetchTask 返回已分配 task，在
   JetStream publish 成功前只重试该 assignment，不领取下一项。
@@ -66,7 +69,7 @@ facade，并严格校验 facade 的 SPIFFE ID。这样无需修改 runner 或把
 - JetStream 只持久化和投递 assignment，不保存 executor 生命周期状态。Pod labels/annotations
   与 OpenSandbox metadata 是后端运行状态的权威来源，Gitea 是 task 终态的权威来源。
 - assignment 使用版本化 envelope 保存完整 Gitea protobuf task，并从 workflow `runs-on`
-  严格选择 pod 或 vm subject；消费者解码后重新派生 backend 与身份，拒绝被篡改的冗余字段。
+  严格选择 workload class 与 driver；消费者解码后重新派生 placement 与身份，拒绝被篡改的冗余字段。
 - JetStream 的 message ID 等于稳定 assignment ID `gitea-task-<task-id>`，仅用于发布去重，
   不承担 executor 生命周期记录。
 - worker 按稳定 assignment ID reconcile 后端资源，进程内只保留并发控制等可丢弃状态；
@@ -76,7 +79,7 @@ facade，并严格校验 facade 的 SPIFFE ID。这样无需修改 runner 或把
 - executor 成功 claim 后 ACK assignment。Gitea 接受 terminal update 后，facade 在后端
   metadata 写入持久 terminal marker；backend reconciler 仅在执行环境也进入终态后清理，
   从而关闭进程重启窗口且避免删除尚未完成结果上报的环境。
-- pod 与 vm 使用独立 durable consumer、进程内 admission pool 和并发上限。consumer 只负责将 assignment
+- 每个 placement 使用独立 durable consumer、进程内 admission pool 和并发上限。consumer 只负责将 assignment
   幂等落到后端；executor 与身份恢复 metadata 持久化后立即 `DoubleAck`。尚未取得
   Pod UID 等短暂未就绪状态以及临时后端错误使用延迟 NAK。
 - admission pool 只保存可重建的并发状态：启动时从 Pod labels/annotations 或 OpenSandbox
@@ -86,10 +89,10 @@ facade，并严格校验 facade 的 SPIFFE ID。这样无需修改 runner 或把
 - consumer 在 executor 使用上述 facade 成功 claim task 后确认 assignment；无需把完整
   task 写入 Pod annotation、OpenSandbox metadata 或环境变量。
 - Pod 与 VM 共享 task/executor 协议，只有环境创建和销毁实现不同。
-- scheduler 在 assignment 持久化到 JetStream 后即可继续领取；Pod 与 VM 分别由 durable
+- scheduler 在 assignment 持久化到 JetStream 后即可继续领取；各 placement 分别由 durable
   consumer 的 capacity 限制并发，不共享全局执行槽位。未知后端故障由对应 consumer 的
   NAK/redelivery 收敛，不能阻塞另一种 backend。
-- 两种 backend 都注入同一份 runner bootstrap 环境；Pod 仍由 homelab Kubernetes 原生
+- 两种现有 driver 都注入同一份 runner bootstrap 环境；container 仍由 homelab Kubernetes 原生
   创建，只有 VM 经 OpenSandbox 创建，bootstrap 机制不改变 backend 边界。
 
 ## 实现顺序
diff --git a/internal/assignmentqueue/jetstream.go b/internal/assignmentqueue/jetstream.go
index 74e8ce6..80de9d5 100644
--- a/internal/assignmentqueue/jetstream.go
+++ b/internal/assignmentqueue/jetstream.go
@@ -19,7 +19,7 @@ type publishAPI interface {
 	PublishMsg(context.Context, *nats.Msg, ...jetstream.PublishOpt) (*jetstream.PubAck, error)
 }
 
-// Publisher implements the scheduler dispatcher with one subject per backend.
+// Publisher implements the scheduler dispatcher with one subject per placement.
 type Publisher struct {
 	JetStream   publishAPI
 	SubjectBase string
@@ -38,7 +38,7 @@ func (p Publisher) Dispatch(ctx context.Context, assignment taskassignment.Assig
 		return errors.New("assignment subject base is required")
 	}
 	message := &nats.Msg{
-		Subject: base + "." + string(assignment.Backend),
+		Subject: base + "." + assignment.Placement.Key(),
 		Header:  nats.Header{jetstream.MsgIDHeader: []string{assignment.ID}},
 		Data:    body,
 	}
@@ -86,13 +86,13 @@ type Processor struct {
 type Event struct {
 	Name         string
 	AssignmentID string
-	Backend      taskassignment.Backend
+	Placement    taskassignment.Placement
 	RetryDelay   time.Duration
 }
 
 func (p Processor) event(name string, assignment taskassignment.Assignment, retryDelay time.Duration) {
 	if p.OnEvent != nil {
-		p.OnEvent(Event{Name: name, AssignmentID: assignment.ID, Backend: assignment.Backend, RetryDelay: retryDelay})
+		p.OnEvent(Event{Name: name, AssignmentID: assignment.ID, Placement: assignment.Placement, RetryDelay: retryDelay})
 	}
 }
 
@@ -178,24 +178,25 @@ type consumerManager interface {
 
 // OpenConsumer creates the durable backend cursor. Capacity is enforced both
 // server-side and by ConsumerComponent's local semaphore.
-func OpenConsumer(ctx context.Context, manager consumerManager, stream, subjectBase string, backend taskassignment.Backend, capacity int) (jetstream.Consumer, error) {
+func OpenConsumer(ctx context.Context, manager consumerManager, stream, subjectBase string, placement taskassignment.Placement, capacity int) (jetstream.Consumer, error) {
 	if manager == nil || stream == "" || strings.TrimSuffix(subjectBase, ".") == "" || capacity < 1 {
 		return nil, errors.New("JetStream manager, stream, subject base, and positive capacity are required")
 	}
-	if backend != taskassignment.BackendPod && backend != taskassignment.BackendVM {
-		return nil, fmt.Errorf("unsupported assignment backend %q", backend)
+	if err := placement.Validate(); err != nil {
+		return nil, err
 	}
+	key := placement.Key()
 	consumer, err := manager.CreateOrUpdateConsumer(ctx, stream, jetstream.ConsumerConfig{
-		Name:          string(backend),
-		Durable:       string(backend),
-		FilterSubject: strings.TrimSuffix(subjectBase, ".") + "." + string(backend),
+		Name:          key,
+		Durable:       key,
+		FilterSubject: strings.TrimSuffix(subjectBase, ".") + "." + key,
 		AckPolicy:     jetstream.AckExplicitPolicy,
 		AckWait:       5 * time.Minute,
 		MaxAckPending: capacity,
 		MaxDeliver:    1000,
 	})
 	if err != nil {
-		return nil, fmt.Errorf("open %s assignment consumer: %w", backend, err)
+		return nil, fmt.Errorf("open %s assignment consumer: %w", key, err)
 	}
 	return consumer, nil
 }
diff --git a/internal/assignmentqueue/jetstream_test.go b/internal/assignmentqueue/jetstream_test.go
index b053208..9c1490f 100644
--- a/internal/assignmentqueue/jetstream_test.go
+++ b/internal/assignmentqueue/jetstream_test.go
@@ -38,13 +38,13 @@ func (p *fakePublisher) PublishMsg(_ context.Context, message *nats.Msg, _ ...je
 	return &jetstream.PubAck{}, nil
 }
 
-func TestPublisherUsesBackendSubjectAndAssignmentDeduplication(t *testing.T) {
+func TestPublisherUsesPlacementSubjectAndAssignmentDeduplication(t *testing.T) {
 	api := &fakePublisher{}
 	publisher := Publisher{JetStream: api, SubjectBase: "ci.assignment"}
 	if err := publisher.Dispatch(context.Background(), testAssignment(t)); err != nil {
 		t.Fatal(err)
 	}
-	if api.message.Subject != "ci.assignment.pod" {
+	if api.message.Subject != "ci.assignment.container.kubernetes" {
 		t.Fatalf("subject = %q", api.message.Subject)
 	}
 	if api.message.Header.Get(jetstream.MsgIDHeader) != "gitea-task-42" {
@@ -139,7 +139,7 @@ func TestProcessorAcknowledgesPersistedHandoff(t *testing.T) {
 		t.Fatalf("events = %#v", events)
 	}
 	for index := range want {
-		if events[index].Name != want[index] || events[index].AssignmentID != "gitea-task-42" || events[index].Backend != taskassignment.BackendPod {
+		if events[index].Name != want[index] || events[index].AssignmentID != "gitea-task-42" || events[index].Placement != taskassignment.KubernetesContainer {
 			t.Fatalf("event[%d] = %#v", index, events[index])
 		}
 	}
@@ -210,12 +210,12 @@ func (m *fakeConsumerManager) CreateOrUpdateConsumer(_ context.Context, _ string
 	return nil, nil
 }
 
-func TestOpenConsumerUsesIndependentDurablePerBackend(t *testing.T) {
+func TestOpenConsumerUsesIndependentDurablePerPlacement(t *testing.T) {
 	manager := &fakeConsumerManager{}
-	if _, err := OpenConsumer(context.Background(), manager, "CI_RUNNER", "ci.assignment", taskassignment.BackendPod, 4); err != nil {
+	if _, err := OpenConsumer(context.Background(), manager, "CI_RUNNER", "ci.assignment", taskassignment.KubernetesContainer, 4); err != nil {
 		t.Fatal(err)
 	}
-	if manager.config.Durable != "pod" || manager.config.FilterSubject != "ci.assignment.pod" || manager.config.AckPolicy != jetstream.AckExplicitPolicy || manager.config.MaxAckPending != 4 || manager.config.MaxDeliver != 1000 {
+	if manager.config.Durable != "container.kubernetes" || manager.config.FilterSubject != "ci.assignment.container.kubernetes" || manager.config.AckPolicy != jetstream.AckExplicitPolicy || manager.config.MaxAckPending != 4 || manager.config.MaxDeliver != 1000 {
 		t.Fatalf("config = %#v", manager.config)
 	}
 }
diff --git a/internal/controller/components.go b/internal/controller/components.go
index 1fcdf48..e3db264 100644
--- a/internal/controller/components.go
+++ b/internal/controller/components.go
@@ -14,12 +14,12 @@ import (
 type ComponentName string
 
 const (
-	Scheduler ComponentName = "scheduler"
-	PodWorker ComponentName = "pod-worker"
-	VMWorker  ComponentName = "vm-worker"
+	Scheduler         ComponentName = "scheduler"
+	KubernetesWorker  ComponentName = "kubernetes-worker"
+	OpenSandboxWorker ComponentName = "opensandbox-worker"
 )
 
-var defaultComponents = []ComponentName{Scheduler, PodWorker, VMWorker}
+var defaultComponents = []ComponentName{Scheduler, KubernetesWorker, OpenSandboxWorker}
 
 // Selection parses --components. An empty value enables all components.
 type Selection []ComponentName
@@ -31,6 +31,12 @@ func ParseSelection(value string) (Selection, error) {
 	var selected Selection
 	for _, raw := range strings.Split(value, ",") {
 		name := ComponentName(strings.TrimSpace(raw))
+		switch name {
+		case "pod-worker":
+			name = KubernetesWorker
+		case "vm-worker":
+			name = OpenSandboxWorker
+		}
 		if !slices.Contains(defaultComponents, name) {
 			return nil, fmt.Errorf("unknown controller component %q", name)
 		}
diff --git a/internal/controller/components_test.go b/internal/controller/components_test.go
index a5cce8c..780dbc2 100644
--- a/internal/controller/components_test.go
+++ b/internal/controller/components_test.go
@@ -13,18 +13,18 @@ func TestParseSelectionDefaultsToAll(t *testing.T) {
 		if err != nil {
 			t.Fatal(err)
 		}
-		if len(selection) != 3 || selection[0] != Scheduler || selection[1] != PodWorker || selection[2] != VMWorker {
+		if len(selection) != 3 || selection[0] != Scheduler || selection[1] != KubernetesWorker || selection[2] != OpenSandboxWorker {
 			t.Fatalf("selection = %v", selection)
 		}
 	}
 }
 
 func TestParseSelectionAllowsOneOrMoreComponents(t *testing.T) {
-	selection, err := ParseSelection("vm-worker,scheduler,vm-worker")
+	selection, err := ParseSelection("opensandbox-worker,scheduler,opensandbox-worker")
 	if err != nil {
 		t.Fatal(err)
 	}
-	if len(selection) != 2 || selection[0] != VMWorker || selection[1] != Scheduler {
+	if len(selection) != 2 || selection[0] != OpenSandboxWorker || selection[1] != Scheduler {
 		t.Fatalf("selection = %v", selection)
 	}
 	if _, err := ParseSelection("webhook"); err == nil {
@@ -32,6 +32,16 @@ func TestParseSelectionAllowsOneOrMoreComponents(t *testing.T) {
 	}
 }
 
+func TestParseSelectionNormalizesLegacyWorkerNames(t *testing.T) {
+	selection, err := ParseSelection("pod-worker,vm-worker")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(selection) != 2 || selection[0] != KubernetesWorker || selection[1] != OpenSandboxWorker {
+		t.Fatalf("selection = %v", selection)
+	}
+}
+
 type componentFunc func(context.Context) error
 
 func (f componentFunc) Run(ctx context.Context) error { return f(ctx) }
@@ -45,14 +55,14 @@ func TestRunStartsSelectedComponentsAndCancelsPeers(t *testing.T) {
 			started <- Scheduler
 			return errors.New("poll failed")
 		}),
-		PodWorker: componentFunc(func(ctx context.Context) error {
-			started <- PodWorker
+		KubernetesWorker: componentFunc(func(ctx context.Context) error {
+			started <- KubernetesWorker
 			<-ctx.Done()
 			once.Do(func() { close(peerStopped) })
 			return ctx.Err()
 		}),
 	}
-	err := Run(context.Background(), Selection{Scheduler, PodWorker}, registry)
+	err := Run(context.Background(), Selection{Scheduler, KubernetesWorker}, registry)
 	if err == nil || !errors.Is(err, context.Canceled) && err.Error() != "component scheduler: poll failed" {
 		t.Fatalf("Run() error = %v", err)
 	}
diff --git a/internal/opensandboxbackend/backend.go b/internal/opensandboxbackend/backend.go
index d81d780..aaf5770 100644
--- a/internal/opensandboxbackend/backend.go
+++ b/internal/opensandboxbackend/backend.go
@@ -119,7 +119,10 @@ func (b Backend) RecoverAssignments(ctx context.Context, trustDomain string) ([]
 		return nil, err
 	}
 	result, err := b.Lifecycle.ListSandboxes(ctx, opensandbox.ListOptions{
-		Metadata: map[string]string{"ci.ddupan.top/backend": "vm"}, PageSize: 100,
+		Metadata: map[string]string{
+			"ci.ddupan.top/workload-class": "vm",
+			"ci.ddupan.top/driver":         "opensandbox",
+		}, PageSize: 100,
 	})
 	if err != nil {
 		return nil, fmt.Errorf("list recoverable sandboxes: %w", err)
@@ -172,8 +175,8 @@ func (b Backend) Create(ctx context.Context, assignment taskassignment.Assignmen
 	if err := b.validate(); err != nil {
 		return nil, err
 	}
-	if assignment.Backend != taskassignment.BackendVM {
-		return nil, fmt.Errorf("OpenSandbox backend cannot create %q assignment", assignment.Backend)
+	if assignment.Placement != taskassignment.OpenSandboxVM {
+		return nil, fmt.Errorf("OpenSandbox backend cannot create %q", assignment.Placement.Key())
 	}
 	environment := clone(b.Config.Env)
 	for key, value := range launch.Environment {
diff --git a/internal/opensandboxbackend/backend_test.go b/internal/opensandboxbackend/backend_test.go
index 4f8dfc0..885d30c 100644
--- a/internal/opensandboxbackend/backend_test.go
+++ b/internal/opensandboxbackend/backend_test.go
@@ -63,7 +63,7 @@ func backend(lifecycle Lifecycle) Backend {
 
 func assignment() taskassignment.Assignment {
 	return taskassignment.Assignment{
-		ID: "gitea-task-42", Backend: taskassignment.BackendVM,
+		ID: "gitea-task-42", Placement: taskassignment.OpenSandboxVM,
 		Task:     &runnerv1.Task{Id: 42},
 		Identity: taskidentity.Identity{Repository: "owner/repo", Task: "publish", SPIFFEID: "spiffe://ddupan.top/ci/owner/repo/publish"},
 	}
diff --git a/internal/podbackend/backend.go b/internal/podbackend/backend.go
index 8f24039..2cc85da 100644
--- a/internal/podbackend/backend.go
+++ b/internal/podbackend/backend.go
@@ -120,7 +120,7 @@ func (b Backend) RecoverAssignments(ctx context.Context) ([]taskassignment.Assig
 	if err := b.validate(); err != nil {
 		return nil, err
 	}
-	pods, err := b.API.ListPods(ctx, b.Config.Namespace, "ci.ddupan.top/backend=pod")
+	pods, err := b.API.ListPods(ctx, b.Config.Namespace, "ci.ddupan.top/workload-class=container,ci.ddupan.top/driver=kubernetes")
 	if err != nil {
 		return nil, fmt.Errorf("list recoverable assignment Pods: %w", err)
 	}
@@ -159,8 +159,8 @@ func (b Backend) Create(ctx context.Context, assignment taskassignment.Assignmen
 	if err := b.validate(); err != nil {
 		return nil, err
 	}
-	if assignment.Backend != taskassignment.BackendPod {
-		return nil, fmt.Errorf("Pod backend cannot create %q assignment", assignment.Backend)
+	if assignment.Placement != taskassignment.KubernetesContainer {
+		return nil, fmt.Errorf("Kubernetes backend cannot create %q", assignment.Placement.Key())
 	}
 	labels := clone(launch.Metadata.Labels)
 	labels["app.kubernetes.io/name"] = "gitea-dynamic-runner"
diff --git a/internal/podbackend/backend_test.go b/internal/podbackend/backend_test.go
index e1d96ba..e928ae8 100644
--- a/internal/podbackend/backend_test.go
+++ b/internal/podbackend/backend_test.go
@@ -59,7 +59,7 @@ func backend(api API) Backend {
 
 func assignment() taskassignment.Assignment {
 	return taskassignment.Assignment{
-		ID: "gitea-task-42", Backend: taskassignment.BackendPod,
+		ID: "gitea-task-42", Placement: taskassignment.KubernetesContainer,
 		Task: &runnerv1.Task{Id: 42},
 		Identity: taskidentity.Identity{
 			Repository: "owner/repo", Task: "publish",
diff --git a/internal/runnerbootstrap/bootstrap.go b/internal/runnerbootstrap/bootstrap.go
index c4151ee..e04499a 100644
--- a/internal/runnerbootstrap/bootstrap.go
+++ b/internal/runnerbootstrap/bootstrap.go
@@ -13,12 +13,13 @@ import (
 )
 
 const (
-	EnvAssignmentID = "CI_ASSIGNMENT_ID"
-	EnvCapability   = "CI_RUNNER_CAPABILITY"
-	EnvFacadeURL    = "CI_RUNNER_FACADE_URL"
-	EnvFacadeID     = "CI_RUNNER_FACADE_SPIFFE_ID"
-	EnvSPIFFEID     = "CI_SPIFFE_ID"
-	EnvBackend      = "CI_RUNNER_BACKEND"
+	EnvAssignmentID  = "CI_ASSIGNMENT_ID"
+	EnvCapability    = "CI_RUNNER_CAPABILITY"
+	EnvFacadeURL     = "CI_RUNNER_FACADE_URL"
+	EnvFacadeID      = "CI_RUNNER_FACADE_SPIFFE_ID"
+	EnvSPIFFEID      = "CI_SPIFFE_ID"
+	EnvWorkloadClass = "CI_WORKLOAD_CLASS"
+	EnvDriver        = "CI_WORKLOAD_DRIVER"
 )
 
 // Bootstrap emits assignment-scoped launch configuration. FacadeURL is the
@@ -48,7 +49,8 @@ func (b Bootstrap) Environment(assignment taskassignment.Assignment) (map[string
 		EnvFacadeURL:             b.FacadeURL,
 		EnvFacadeID:              b.FacadeSPIFFEID,
 		EnvSPIFFEID:              assignment.Identity.SPIFFEID,
-		EnvBackend:               string(assignment.Backend),
+		EnvWorkloadClass:         string(assignment.Placement.Class),
+		EnvDriver:                string(assignment.Placement.Driver),
 		"SPIFFE_ENDPOINT_SOCKET": b.WorkloadAPIAddr,
 	}, nil
 }
@@ -67,7 +69,7 @@ type Registration struct {
 	Ephemeral bool     `json:"ephemeral"`
 }
 
-func RegistrationJSON(assignmentID, capability, localProxyURL string, backend taskassignment.Backend) ([]byte, error) {
+func RegistrationJSON(assignmentID, capability, localProxyURL string, placement taskassignment.Placement) ([]byte, error) {
 	if assignmentID == "" || capability == "" {
 		return nil, errors.New("assignment ID and runner capability are required")
 	}
@@ -75,13 +77,13 @@ func RegistrationJSON(assignmentID, capability, localProxyURL string, backend ta
 	if err != nil || parsed.Scheme != "http" || parsed.Host == "" {
 		return nil, errors.New("local runner proxy URL must be an absolute http URL")
 	}
-	if backend != taskassignment.BackendPod && backend != taskassignment.BackendVM {
-		return nil, fmt.Errorf("unsupported runner backend %q", backend)
+	if err := placement.Validate(); err != nil {
+		return nil, err
 	}
 	registration := Registration{
 		Warning: "Generated for one preassigned task by gitea-dynamic-runner.",
 		UUID:    assignmentID, Name: assignmentID, Token: capability,
-		Address: localProxyURL, Labels: []string{"self-hosted", string(backend)}, Ephemeral: true,
+		Address: localProxyURL, Labels: []string{"self-hosted", string(placement.Class), string(placement.Driver)}, Ephemeral: true,
 	}
 	data, err := json.MarshalIndent(registration, "", "  ")
 	if err != nil {
diff --git a/internal/runnerbootstrap/bootstrap_test.go b/internal/runnerbootstrap/bootstrap_test.go
index 0ab3fbf..5f2aaa9 100644
--- a/internal/runnerbootstrap/bootstrap_test.go
+++ b/internal/runnerbootstrap/bootstrap_test.go
@@ -25,7 +25,7 @@ func testBootstrap(t *testing.T) Bootstrap {
 
 func testAssignment() taskassignment.Assignment {
 	return taskassignment.Assignment{
-		ID: "gitea-task-42", Backend: taskassignment.BackendPod,
+		ID: "gitea-task-42", Placement: taskassignment.KubernetesContainer,
 		Identity: taskidentity.Identity{SPIFFEID: "spiffe://ddupan.top/ci/owner/repo/publish"},
 	}
 }
@@ -46,7 +46,7 @@ func TestEnvironmentIsDeterministicAndAssignmentScoped(t *testing.T) {
 	if first[EnvAssignmentID] != "gitea-task-42" || first[EnvSPIFFEID] != testAssignment().Identity.SPIFFEID {
 		t.Fatalf("environment = %#v", first)
 	}
-	if first[EnvBackend] != "pod" || first[EnvFacadeID] == "" {
+	if first[EnvWorkloadClass] != "container" || first[EnvDriver] != "kubernetes" || first[EnvFacadeID] == "" {
 		t.Fatalf("environment = %#v", first)
 	}
 	if first["SPIFFE_ENDPOINT_SOCKET"] != "unix:///run/spire/agent-sockets/spire-agent.sock" {
@@ -55,7 +55,7 @@ func TestEnvironmentIsDeterministicAndAssignmentScoped(t *testing.T) {
 }
 
 func TestRegistrationMatchesOfficialRunnerSchema(t *testing.T) {
-	data, err := RegistrationJSON("gitea-task-42", "capability", "http://127.0.0.1:8080", taskassignment.BackendVM)
+	data, err := RegistrationJSON("gitea-task-42", "capability", "http://127.0.0.1:8080", taskassignment.OpenSandboxVM)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -66,13 +66,13 @@ func TestRegistrationMatchesOfficialRunnerSchema(t *testing.T) {
 	if registration.UUID != "gitea-task-42" || registration.Token != "capability" || registration.Address != "http://127.0.0.1:8080" || !registration.Ephemeral {
 		t.Fatalf("registration = %#v", registration)
 	}
-	if len(registration.Labels) != 2 || registration.Labels[0] != "self-hosted" || registration.Labels[1] != "vm" {
+	if len(registration.Labels) != 3 || registration.Labels[0] != "self-hosted" || registration.Labels[1] != "vm" || registration.Labels[2] != "opensandbox" {
 		t.Fatalf("labels = %#v", registration.Labels)
 	}
 }
 
 func TestRegistrationRejectsNonLocalTLSAddress(t *testing.T) {
-	if _, err := RegistrationJSON("id", "capability", "https://facade.example", taskassignment.BackendPod); err == nil {
+	if _, err := RegistrationJSON("id", "capability", "https://facade.example", taskassignment.KubernetesContainer); err == nil {
 		t.Fatal("expected local proxy URL validation error")
 	}
 }
diff --git a/internal/runnerbootstrap/executor.go b/internal/runnerbootstrap/executor.go
index 4158b81..c3415e0 100644
--- a/internal/runnerbootstrap/executor.go
+++ b/internal/runnerbootstrap/executor.go
@@ -17,7 +17,7 @@ import (
 type ExecutorConfig struct {
 	AssignmentID    string
 	Capability      string
-	Backend         taskassignment.Backend
+	Placement       taskassignment.Placement
 	FacadeURL       string
 	FacadeSPIFFEID  string
 	WorkloadAPIAddr string
@@ -71,7 +71,7 @@ func RunExecutor(ctx context.Context, config ExecutorConfig) error {
 		defer os.RemoveAll(workDir)
 	}
 	registration, err := RegistrationJSON(
-		config.AssignmentID, config.Capability, "http://"+listener.Addr().String(), config.Backend,
+		config.AssignmentID, config.Capability, "http://"+listener.Addr().String(), config.Placement,
 	)
 	if err != nil {
 		return err
@@ -144,13 +144,13 @@ func waitForFacade(ctx context.Context, endpoint string) error {
 // the assignment-scoped values injected by the backend. The Workload API
 // address follows SPIFFE_ENDPOINT_SOCKET through go-spiffe when not set here.
 func ExecutorConfigFromEnvironment() (ExecutorConfig, error) {
-	backend := taskassignment.Backend(os.Getenv(EnvBackend))
-	if backend != taskassignment.BackendPod && backend != taskassignment.BackendVM {
-		return ExecutorConfig{}, fmt.Errorf("invalid %s %q", EnvBackend, backend)
+	placement := taskassignment.Placement{Class: taskassignment.WorkloadClass(os.Getenv(EnvWorkloadClass)), Driver: taskassignment.Driver(os.Getenv(EnvDriver))}
+	if err := placement.Validate(); err != nil {
+		return ExecutorConfig{}, err
 	}
 	config := ExecutorConfig{
 		AssignmentID: os.Getenv(EnvAssignmentID), Capability: os.Getenv(EnvCapability),
-		Backend: backend, FacadeURL: os.Getenv(EnvFacadeURL), FacadeSPIFFEID: os.Getenv(EnvFacadeID),
+		Placement: placement, FacadeURL: os.Getenv(EnvFacadeURL), FacadeSPIFFEID: os.Getenv(EnvFacadeID),
 		RunnerBinary: os.Getenv("GITEA_RUNNER_BINARY"), RunnerConfig: os.Getenv("GITEA_RUNNER_CONFIG_FILE"),
 		ListenAddress: "127.0.0.1:0",
 		Stdout:        os.Stdout, Stderr: os.Stderr,
diff --git a/internal/taskassignment/assignment.go b/internal/taskassignment/assignment.go
index 497df49..2c5f0aa 100644
--- a/internal/taskassignment/assignment.go
+++ b/internal/taskassignment/assignment.go
@@ -6,7 +6,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"slices"
 	"strconv"
 
 	"gitea.dev/actionslib/pkg/model"
@@ -16,34 +15,27 @@ import (
 	"git.ddupan.top/panxiao81/gitea-dynamic-runner/internal/taskidentity"
 )
 
-const wireVersion = 1
-
-type Backend string
-
-const (
-	BackendPod Backend = "pod"
-	BackendVM  Backend = "vm"
-)
+const wireVersion = 2
 
 // Assignment is the only document persisted in the handoff queue.
 type Assignment struct {
-	ID       string
-	Backend  Backend
-	Task     *runnerv1.Task
-	Identity taskidentity.Identity
+	ID        string
+	Placement Placement
+	Task      *runnerv1.Task
+	Identity  taskidentity.Identity
 }
 
 // FromMetadata reconstructs the minimal assignment needed to authorize an
-// already-running executor after a controller restart. Backend metadata was
+// already-running executor after a controller restart. Placement metadata was
 // originally derived from the trusted Gitea task and is validated again here.
 func FromMetadata(labels, annotations map[string]string, trustDomain string) (Assignment, error) {
 	taskID, err := strconv.ParseInt(labels["ci.ddupan.top/task-id"], 10, 64)
 	if err != nil || taskID < 1 {
 		return Assignment{}, errors.New("backend metadata has invalid task ID")
 	}
-	backend := Backend(labels["ci.ddupan.top/backend"])
-	if backend != BackendPod && backend != BackendVM {
-		return Assignment{}, errors.New("backend metadata has invalid backend")
+	placement := Placement{Class: WorkloadClass(labels["ci.ddupan.top/workload-class"]), Driver: Driver(labels["ci.ddupan.top/driver"])}
+	if err := placement.Validate(); err != nil {
+		return Assignment{}, err
 	}
 	id := labels["ci.ddupan.top/assignment-id"]
 	if id != fmt.Sprintf("gitea-task-%d", taskID) {
@@ -56,15 +48,15 @@ func FromMetadata(labels, annotations map[string]string, trustDomain string) (As
 	if err != nil {
 		return Assignment{}, err
 	}
-	return Assignment{ID: id, Backend: backend, Task: &runnerv1.Task{Id: taskID}, Identity: identity}, nil
+	return Assignment{ID: id, Placement: placement, Task: &runnerv1.Task{Id: taskID}, Identity: identity}, nil
 }
 
 type envelope struct {
-	Version  int                   `json:"version"`
-	ID       string                `json:"id"`
-	Backend  Backend               `json:"backend"`
-	Task     []byte                `json:"task"`
-	Identity taskidentity.Identity `json:"identity"`
+	Version   int                   `json:"version"`
+	ID        string                `json:"id"`
+	Placement Placement             `json:"placement"`
+	Task      []byte                `json:"task"`
+	Identity  taskidentity.Identity `json:"identity"`
 }
 
 // New derives all trusted assignment fields from the task fetched from Gitea.
@@ -76,40 +68,28 @@ func New(task *runnerv1.Task, trustDomain string) (Assignment, error) {
 	if err != nil {
 		return Assignment{}, err
 	}
-	backend, err := backendFromTask(task)
+	placement, err := placementFromTask(task)
 	if err != nil {
 		return Assignment{}, err
 	}
 	return Assignment{
-		ID:       fmt.Sprintf("gitea-task-%d", task.GetId()),
-		Backend:  backend,
-		Task:     task,
-		Identity: identity,
+		ID:        fmt.Sprintf("gitea-task-%d", task.GetId()),
+		Placement: placement,
+		Task:      task,
+		Identity:  identity,
 	}, nil
 }
 
-func backendFromTask(task *runnerv1.Task) (Backend, error) {
+func placementFromTask(task *runnerv1.Task) (Placement, error) {
 	workflow, err := model.ReadWorkflow(bytes.NewReader(task.GetWorkflowPayload()))
 	if err != nil {
-		return "", fmt.Errorf("parse task workflow for backend: %w", err)
+		return Placement{}, fmt.Errorf("parse task workflow for placement: %w", err)
 	}
 	jobIDs := workflow.GetJobIDs()
 	if len(jobIDs) != 1 || workflow.GetJob(jobIDs[0]) == nil {
-		return "", fmt.Errorf("task workflow must contain exactly one non-empty job")
+		return Placement{}, fmt.Errorf("task workflow must contain exactly one non-empty job")
 	}
-	labels := workflow.GetJob(jobIDs[0]).RunsOnLabels()
-	if !slices.Contains(labels, "self-hosted") {
-		return "", fmt.Errorf("task runs-on labels must include self-hosted: %v", labels)
-	}
-	hasPod := slices.Contains(labels, string(BackendPod))
-	hasVM := slices.Contains(labels, string(BackendVM)) || slices.Contains(labels, "vm-dev")
-	if hasPod == hasVM {
-		return "", fmt.Errorf("task runs-on labels must select exactly one of pod or vm: %v", labels)
-	}
-	if hasPod {
-		return BackendPod, nil
-	}
-	return BackendVM, nil
+	return PlacementFromLabels(workflow.GetJob(jobIDs[0]).RunsOnLabels())
 }
 
 // Marshal encodes a versioned assignment. Protobuf preserves the exact Gitea task.
@@ -117,13 +97,16 @@ func Marshal(assignment Assignment) ([]byte, error) {
 	if assignment.Task == nil {
 		return nil, errors.New("assignment task is required")
 	}
+	if err := assignment.Placement.Validate(); err != nil {
+		return nil, err
+	}
 	task, err := proto.Marshal(assignment.Task)
 	if err != nil {
 		return nil, fmt.Errorf("marshal Gitea task: %w", err)
 	}
 	return json.Marshal(envelope{
 		Version: wireVersion,
-		ID:      assignment.ID, Backend: assignment.Backend,
+		ID:      assignment.ID, Placement: assignment.Placement,
 		Task: task, Identity: assignment.Identity,
 	})
 }
@@ -145,7 +128,7 @@ func Unmarshal(data []byte, trustDomain string) (Assignment, error) {
 	if err != nil {
 		return Assignment{}, err
 	}
-	if wire.ID != canonical.ID || wire.Backend != canonical.Backend || wire.Identity != canonical.Identity {
+	if wire.ID != canonical.ID || wire.Placement != canonical.Placement || wire.Identity != canonical.Identity {
 		return Assignment{}, errors.New("assignment metadata does not match its Gitea task")
 	}
 	return canonical, nil
diff --git a/internal/taskassignment/assignment_test.go b/internal/taskassignment/assignment_test.go
index d2413db..0733338 100644
--- a/internal/taskassignment/assignment_test.go
+++ b/internal/taskassignment/assignment_test.go
@@ -21,29 +21,37 @@ func task(t *testing.T, labels string) *runnerv1.Task {
 	}
 }
 
-func TestNewSelectsBackendFromRunsOn(t *testing.T) {
+func TestNewSelectsPlacementFromRunsOn(t *testing.T) {
 	for _, test := range []struct {
-		labels  string
-		backend Backend
+		labels    string
+		placement Placement
 	}{
-		{"[self-hosted, pod]", BackendPod},
-		{"[self-hosted, vm]", BackendVM},
-		{"[self-hosted, vm-dev]", BackendVM},
+		{"[self-hosted, pod]", KubernetesContainer},
+		{"[self-hosted, container]", KubernetesContainer},
+		{"[self-hosted, container, kubernetes]", KubernetesContainer},
+		{"[self-hosted, vm]", OpenSandboxVM},
+		{"[self-hosted, vm-dev]", OpenSandboxVM},
+		{"[self-hosted, vm, opensandbox]", OpenSandboxVM},
 	} {
 		assignment, err := New(task(t, test.labels), "ddupan.top")
 		if err != nil {
 			t.Fatal(err)
 		}
-		if assignment.Backend != test.backend || assignment.ID != "gitea-task-42" {
+		if assignment.Placement != test.placement || assignment.ID != "gitea-task-42" {
 			t.Fatalf("assignment = %#v", assignment)
 		}
 	}
 }
 
-func TestNewRejectsAmbiguousBackend(t *testing.T) {
+func TestNewRejectsInvalidPlacement(t *testing.T) {
 	for _, labels := range []string{
 		"[self-hosted]",
 		"[self-hosted, pod, vm]",
+		"[self-hosted, pod, container]",
+		"[self-hosted, pod, kubernetes]",
+		"[self-hosted, container, opensandbox]",
+		"[self-hosted, vm, kubernetes]",
+		"[self-hosted, container, kubernetes, opensandbox]",
 		"[pod]",
 	} {
 		if _, err := New(task(t, labels), "ddupan.top"); err == nil {
@@ -65,27 +73,28 @@ func TestAssignmentWireRoundTripAndValidation(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if got.ID != want.ID || got.Backend != want.Backend || got.Identity != want.Identity || !bytes.Equal(got.Task.WorkflowPayload, want.Task.WorkflowPayload) {
+	if got.ID != want.ID || got.Placement != want.Placement || got.Identity != want.Identity || !bytes.Equal(got.Task.WorkflowPayload, want.Task.WorkflowPayload) {
 		t.Fatalf("round trip = %#v, want %#v", got, want)
 	}
 
-	tampered := bytes.Replace(data, []byte(`"backend":"pod"`), []byte(`"backend":"vm"`), 1)
+	tampered := bytes.Replace(data, []byte(`"driver":"kubernetes"`), []byte(`"driver":"opensandbox"`), 1)
 	if _, err := Unmarshal(tampered, "ddupan.top"); err == nil {
-		t.Fatal("expected tampered backend to fail")
+		t.Fatal("expected tampered placement to fail")
 	}
 }
 
 func TestFromMetadataRecoversMinimalAssignment(t *testing.T) {
 	assignment, err := FromMetadata(map[string]string{
-		"ci.ddupan.top/assignment-id": "gitea-task-42",
-		"ci.ddupan.top/task-id":       "42",
-		"ci.ddupan.top/backend":       "vm",
+		"ci.ddupan.top/assignment-id":  "gitea-task-42",
+		"ci.ddupan.top/task-id":        "42",
+		"ci.ddupan.top/workload-class": "vm",
+		"ci.ddupan.top/driver":         "opensandbox",
 	}, map[string]string{
 		"ci.ddupan.top/repository": "owner/repo",
 		"ci.ddupan.top/job-key":    "publish",
 		"ci.ddupan.top/spiffe-id":  "spiffe://ddupan.top/ci/owner/repo/publish",
 	}, "ddupan.top")
-	if err != nil || assignment.Task.GetId() != 42 || assignment.Backend != BackendVM {
+	if err != nil || assignment.Task.GetId() != 42 || assignment.Placement != OpenSandboxVM {
 		t.Fatalf("assignment=%#v err=%v", assignment, err)
 	}
 }
diff --git a/internal/taskassignment/placement.go b/internal/taskassignment/placement.go
new file mode 100644
index 0000000..8b218a5
--- /dev/null
+++ b/internal/taskassignment/placement.go
@@ -0,0 +1,76 @@
+package taskassignment
+
+import (
+	"errors"
+	"fmt"
+	"slices"
+)
+
+type WorkloadClass string
+
+const (
+	WorkloadContainer WorkloadClass = "container"
+	WorkloadVM        WorkloadClass = "vm"
+)
+
+type Driver string
+
+const (
+	DriverKubernetes  Driver = "kubernetes"
+	DriverOpenSandbox Driver = "opensandbox"
+)
+
+type Placement struct {
+	Class  WorkloadClass `json:"workload_class"`
+	Driver Driver        `json:"driver"`
+}
+
+var (
+	KubernetesContainer = Placement{Class: WorkloadContainer, Driver: DriverKubernetes}
+	OpenSandboxVM       = Placement{Class: WorkloadVM, Driver: DriverOpenSandbox}
+)
+
+func (p Placement) Validate() error {
+	switch p {
+	case KubernetesContainer, OpenSandboxVM:
+		return nil
+	default:
+		return fmt.Errorf("unsupported workload placement %s/%s", p.Class, p.Driver)
+	}
+}
+
+func (p Placement) Key() string { return string(p.Class) + "." + string(p.Driver) }
+
+func PlacementFromLabels(labels []string) (Placement, error) {
+	if !slices.Contains(labels, "self-hosted") {
+		return Placement{}, fmt.Errorf("task runs-on labels must include self-hosted: %v", labels)
+	}
+	legacyPod := slices.Contains(labels, "pod")
+	container := slices.Contains(labels, string(WorkloadContainer))
+	vm := slices.Contains(labels, string(WorkloadVM)) || slices.Contains(labels, "vm-dev")
+	kubernetes := slices.Contains(labels, string(DriverKubernetes))
+	opensandbox := slices.Contains(labels, string(DriverOpenSandbox))
+
+	if legacyPod {
+		if container || vm || kubernetes || opensandbox {
+			return Placement{}, errors.New("legacy pod label cannot be combined with workload or VM driver labels")
+		}
+		return KubernetesContainer, nil
+	}
+	if container == vm {
+		return Placement{}, fmt.Errorf("task runs-on labels must select exactly one workload class: %v", labels)
+	}
+	if kubernetes && opensandbox {
+		return Placement{}, fmt.Errorf("task runs-on labels select multiple drivers: %v", labels)
+	}
+	if container {
+		if opensandbox {
+			return Placement{}, fmt.Errorf("opensandbox does not support container workloads")
+		}
+		return KubernetesContainer, nil
+	}
+	if kubernetes {
+		return Placement{}, fmt.Errorf("kubernetes does not support VM workloads")
+	}
+	return OpenSandboxVM, nil
+}
diff --git a/internal/taskworker/worker.go b/internal/taskworker/worker.go
index ea590ad..f307df9 100644
--- a/internal/taskworker/worker.go
+++ b/internal/taskworker/worker.go
@@ -206,10 +206,11 @@ func (w Worker) launchSpec(assignment taskassignment.Assignment) (LaunchSpec, er
 func BackendMetadata(assignment taskassignment.Assignment) Metadata {
 	return Metadata{
 		Labels: map[string]string{
-			"ci.ddupan.top/runner":        "true",
-			"ci.ddupan.top/assignment-id": assignment.ID,
-			"ci.ddupan.top/task-id":       strconv.FormatInt(assignment.Task.GetId(), 10),
-			"ci.ddupan.top/backend":       string(assignment.Backend),
+			"ci.ddupan.top/runner":         "true",
+			"ci.ddupan.top/assignment-id":  assignment.ID,
+			"ci.ddupan.top/task-id":        strconv.FormatInt(assignment.Task.GetId(), 10),
+			"ci.ddupan.top/workload-class": string(assignment.Placement.Class),
+			"ci.ddupan.top/driver":         string(assignment.Placement.Driver),
 		},
 		Annotations: map[string]string{
 			"ci.ddupan.top/repository": assignment.Identity.Repository,
diff --git a/internal/taskworker/worker_test.go b/internal/taskworker/worker_test.go
index efdf111..c76ae1d 100644
--- a/internal/taskworker/worker_test.go
+++ b/internal/taskworker/worker_test.go
@@ -53,9 +53,9 @@ func (t *fakeTasks) Report(_ context.Context, _ int64, phase Phase) error {
 
 func assignment() taskassignment.Assignment {
 	return taskassignment.Assignment{
-		ID:      "gitea-task-42",
-		Backend: taskassignment.BackendPod,
-		Task:    &runnerv1.Task{Id: 42},
+		ID:        "gitea-task-42",
+		Placement: taskassignment.KubernetesContainer,
+		Task:      &runnerv1.Task{Id: 42},
 		Identity: taskidentity.Identity{
 			Repository: "owner/repo",
 			Task:       "publish",