feat: 隔离 VM 集成测试标签

.gitea/workflows/vm-kind-smoke.yml

@@ -5,7 +5,7 @@ on:
 
 jobs:
   kind:
-    runs-on: [self-hosted, vm]
+    runs-on: [self-hosted, vm-dev]
     steps:
       - name: Verify Docker
         run: docker info

README.md

@@ -15,10 +15,15 @@ runs-on: [self-hosted, vm]
 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)。
 
+集成期间可将 `VM_RUNNER_LABEL=vm-dev`，只接取显式使用
+`runs-on: [self-hosted, vm-dev]` 的测试任务；生产 `vm` job 将保持在 Gitea pending，
+不会在 backend 修复过程中继续涌入。
+
 目标 Go controller 组件：
 
 - `scheduler`：以常驻 Gitea RunnerService 身份直接领取 task，并把完整 assignment
-  持久化到 JetStream；同时提供仅允许 SPIFFE mTLS 的 RunnerService facade。
+  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。
 - 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
@@ -37,8 +42,9 @@ runs-on: [self-hosted, vm]
   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，任一执行层故障不会阻塞另一条
+VM/Kata workload；两个 backend 使用独立 durable consumer 和独立容量池。assignment 根据
-部署。长期 RunnerService 协议路线见
+`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)。
 
 ## 开发

cmd/gitea-dynamic-runner/controller.go

@@ -22,6 +22,7 @@ import (
 	"k8s.io/client-go/tools/leaderelection/resourcelock"
 
 	"git.ddupan.top/panxiao81/gitea-dynamic-runner/internal/assignmentqueue"
+	"git.ddupan.top/panxiao81/gitea-dynamic-runner/internal/backendpool"
 	"git.ddupan.top/panxiao81/gitea-dynamic-runner/internal/controller"
 	"git.ddupan.top/panxiao81/gitea-dynamic-runner/internal/giteaactions"
 	"git.ddupan.top/panxiao81/gitea-dynamic-runner/internal/opensandboxbackend"
@@ -48,7 +49,7 @@ type controllerConfig struct {
 	PodNamespace, PodImage, PodServiceAccount, SPIRECluster, SPIREClass string
 	SPIREAgentID                                                        string
 	PodExecutorUID, PodCapacity                                         int
-	OpenSandboxURL, OpenSandboxAPIKey, OpenSandboxPool                  string
+	OpenSandboxURL, OpenSandboxAPIKey, OpenSandboxPool, VMRunnerLabel   string
 	VMTimeout, VMCapacity                                               int
 }
 
@@ -91,6 +92,8 @@ 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
 	giteaClient := giteaactions.NewClient(giteaactions.DefaultHTTPClient(), config.GiteaURL, config.GiteaUUID, config.GiteaToken)
@@ -105,6 +108,7 @@ func runController(ctx context.Context) error {
 				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")
@@ -112,6 +116,7 @@ func runController(ctx context.Context) error {
 				if err := vmExecutorBackend.MarkTerminal(ctx, assignment.ID); err != nil {
 					return err
 				}
+				vmPool.Release(assignment.ID)
 			}
 			return nil
 		},
@@ -126,14 +131,14 @@ func runController(ctx context.Context) error {
 		labels = append(labels, string(taskassignment.BackendPod))
 	}
 	if slices.Contains(config.Components, controller.VMWorker) {
-		labels = append(labels, string(taskassignment.BackendVM))
+		labels = append(labels, config.VMRunnerLabel)
 	}
 	poller := taskscheduler.Poller{
 		Client: giteaClient,
 		Scheduler: &taskscheduler.Scheduler{TrustDomain: config.TrustDomain, Dispatcher: assignmentqueue.Publisher{
 			JetStream: producerJS, SubjectBase: config.SubjectBase,
 		}},
-		Config:  taskscheduler.PollerConfig{Version: "gitea-dynamic-runner/0.4", Labels: labels},
+		Config:  taskscheduler.PollerConfig{Version: "gitea-dynamic-runner/0.4", Labels: labels, Capacity: config.PodCapacity + config.VMCapacity},
 		OnError: func(err error) { log.Printf("scheduler: %v", err) },
 	}
 	kubernetesConfig, err := rest.InClusterConfig()
@@ -180,11 +185,12 @@ func runController(ctx context.Context) error {
 			return err
 		}
 		for _, assignment := range assignments {
+			podPool.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}, registry)
+		component, err := workerComponent(ctx, workerJS, config, taskassignment.BackendPod, config.PodCapacity, taskworker.Worker{Backend: backend, Bootstrap: bootstrap}, registry, podPool)
 		if err != nil {
 			return err
 		}
@@ -209,11 +215,12 @@ func runController(ctx context.Context) error {
 			return err
 		}
 		for _, assignment := range assignments {
+			vmPool.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}, registry)
+		component, err := workerComponent(ctx, workerJS, config, taskassignment.BackendVM, config.VMCapacity, taskworker.Worker{Backend: backend, Bootstrap: bootstrap}, registry, vmPool)
 		if err != nil {
 			return err
 		}
@@ -280,14 +287,14 @@ 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) (controller.Component, error) {
+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)
 	if err != nil {
 		return nil, err
 	}
 	return assignmentqueue.ConsumerComponent{
 		Consumer: consumer, Capacity: capacity,
-		Processor: assignmentqueue.Processor{TrustDomain: config.TrustDomain, Accepter: accepter, Claims: claims},
+		Processor: assignmentqueue.Processor{TrustDomain: config.TrustDomain, Accepter: accepter, Claims: claims, Admission: admission},
 		OnError:   func(err error) { log.Printf("%s worker: %v", backend, err) },
 	}, nil
 }
@@ -338,7 +345,7 @@ func loadControllerConfig() (controllerConfig, error) {
 		FacadeListen: env("RUNNER_FACADE_LISTEN", ":8443"), FacadeURL: os.Getenv("RUNNER_FACADE_URL"), FacadeSPIFFEID: os.Getenv("RUNNER_FACADE_SPIFFE_ID"), CapabilityKey: []byte(capabilityKey),
 		PodNamespace: env("POD_NAMESPACE", "gitea-actions"), PodImage: os.Getenv("POD_EXECUTOR_IMAGE"), PodServiceAccount: env("POD_SERVICE_ACCOUNT", "gitea-task-executor"),
 		SPIRECluster: env("SPIRE_CLUSTER", "homelab"), SPIREClass: env("SPIRE_CLASS", "spire-mgmt-spire"), SPIREAgentID: os.Getenv("SPIRE_AGENT_ID"), PodExecutorUID: envInt("POD_EXECUTOR_UID", 2000), PodCapacity: envInt("POD_CAPACITY", 4),
-		OpenSandboxURL: os.Getenv("OPENSANDBOX_API"), OpenSandboxPool: env("OPENSANDBOX_POOL", "ci-vm"), VMTimeout: envInt("VM_TIMEOUT_SECONDS", 14400), VMCapacity: envInt("VM_CAPACITY", 1),
+		OpenSandboxURL: os.Getenv("OPENSANDBOX_API"), OpenSandboxPool: env("OPENSANDBOX_POOL", "ci-vm"), VMRunnerLabel: env("VM_RUNNER_LABEL", "vm"), VMTimeout: envInt("VM_TIMEOUT_SECONDS", 14400), VMCapacity: envInt("VM_CAPACITY", 1),
 	}
 	if config.WorkloadAPIAddr == "" || config.FacadeURL == "" || config.FacadeSPIFFEID == "" {
 		return controllerConfig{}, errors.New("SPIFFE_ENDPOINT_SOCKET, RUNNER_FACADE_URL, and RUNNER_FACADE_SPIFFE_ID are required")
@@ -350,6 +357,9 @@ func loadControllerConfig() (controllerConfig, error) {
 		return controllerConfig{}, errors.New("SPIRE_AGENT_ID is required for pod-worker")
 	}
 	if slices.Contains(selection, controller.VMWorker) {
+		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")
 		}

cmd/gitea-dynamic-runner/controller_test.go

@@ -56,6 +56,7 @@ func TestLoadControllerConfigRequiresOpenSandboxSecretOnlyForVM(t *testing.T) {
 	t.Setenv("RUNNER_FACADE_URL", "https://facade:8443")
 	t.Setenv("RUNNER_FACADE_SPIFFE_ID", "spiffe://ddupan.top/controller")
 	t.Setenv("OPENSANDBOX_API", "http://opensandbox.internal")
+	t.Setenv("VM_RUNNER_LABEL", "vm-dev")
 	if _, err := loadControllerConfig(); err == nil {
 		t.Fatal("expected missing OpenSandbox API key file error")
 	}

docs/runner-protocol-roadmap.md

@@ -3,8 +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；它只在后端存在可用容量
+协议客户端注册，并声明 `self-hosted`、`pod` 和 `vm` labels；单个 registration 内按总
-时领取 task，然后将该 task 交给一个一次性 Pod 或 microVM 执行。
+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。
 
 ```text
 Gitea RunnerService
@@ -47,7 +48,10 @@ 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。
-- scheduler 在没有对应 backend 容量时不领取 task，避免本地形成不可控积压。
+- 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，
+  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。
 - 每个 executor 只执行一个 task，完成后销毁。
@@ -72,9 +76,11 @@ 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 和并发上限。consumer 只负责将 assignment
+- 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
   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
+  metadata 恢复非终态 assignment，terminal update 持久化成功后释放槽位，不引入新存储。
 - assignment ACK 后的运行、结果回报和清理由 backend reconciler 根据 Kubernetes、
   OpenSandbox 与 Gitea 的事实状态驱动，不继续占用 JetStream delivery。
 - consumer 在 executor 使用上述 facade 成功 claim task 后确认 assignment；无需把完整

internal/assignmentqueue/jetstream.go

@@ -57,6 +57,11 @@ type Claims interface {
 	WaitClaimed(context.Context, string) error
 }
 
+type Admission interface {
+	Acquire(string) bool
+	Release(string)
+}
+
 // Message is the subset of jetstream.Msg needed by one reconciliation.
 type Message interface {
 	Data() []byte
@@ -70,13 +75,14 @@ type Processor struct {
 	TrustDomain  string
 	Accepter     Accepter
 	Claims       Claims
+	Admission    Admission
 	RetryDelay   time.Duration
 	ClaimTimeout time.Duration
 }
 
 func (p Processor) Process(ctx context.Context, message Message) error {
-	if p.Accepter == nil || p.Claims == nil {
+	if p.Accepter == nil || p.Claims == nil || p.Admission == nil {
-		return errors.New("assignment accepter and claim registry are required")
+		return errors.New("assignment accepter, claim registry, and backend admission pool are required")
 	}
 	assignment, err := taskassignment.Unmarshal(message.Data(), p.TrustDomain)
 	if err != nil {
@@ -85,8 +91,16 @@ func (p Processor) Process(ctx context.Context, message Message) error {
 	if _, err := p.Claims.Offer(assignment); err != nil {
 		return errors.Join(err, message.TermWithReason("conflicting assignment"))
 	}
+	if !p.Admission.Acquire(assignment.ID) {
+		delay := p.RetryDelay
+		if delay <= 0 {
+			delay = 2 * time.Second
+		}
+		return message.NakWithDelay(delay)
+	}
 	accepted, err := p.Accepter.Accept(ctx, assignment)
 	if err != nil {
+		p.Admission.Release(assignment.ID)
 		delay := p.RetryDelay
 		if delay <= 0 {
 			delay = 15 * time.Second
@@ -153,7 +167,7 @@ func OpenConsumer(ctx context.Context, manager consumerManager, stream, subjectB
 		AckPolicy:     jetstream.AckExplicitPolicy,
 		AckWait:       5 * time.Minute,
 		MaxAckPending: capacity,
-		MaxDeliver:    20,
+		MaxDeliver:    1000,
 	})
 	if err != nil {
 		return nil, fmt.Errorf("open %s assignment consumer: %w", backend, err)

internal/assignmentqueue/jetstream_test.go

@@ -61,6 +61,28 @@ type fakeClaims struct {
 	claimed bool
 }
 
+type fakeAdmission struct {
+	allowed  bool
+	active   map[string]bool
+	released int
+}
+
+func (a *fakeAdmission) Acquire(assignmentID string) bool {
+	if !a.allowed {
+		return false
+	}
+	if a.active == nil {
+		a.active = make(map[string]bool)
+	}
+	a.active[assignmentID] = true
+	return true
+}
+
+func (a *fakeAdmission) Release(assignmentID string) {
+	delete(a.active, assignmentID)
+	a.released++
+}
+
 func (c *fakeClaims) Offer(taskassignment.Assignment) (<-chan struct{}, error) {
 	ready := make(chan struct{})
 	if c.claimed {
@@ -104,7 +126,7 @@ func encodedAssignment(t *testing.T) []byte {
 
 func TestProcessorAcknowledgesPersistedHandoff(t *testing.T) {
 	message := &fakeMessage{data: encodedAssignment(t)}
-	processor := Processor{TrustDomain: "ddupan.top", Accepter: &fakeAccepter{accepted: true}, Claims: &fakeClaims{claimed: true}}
+	processor := Processor{TrustDomain: "ddupan.top", Accepter: &fakeAccepter{accepted: true}, Claims: &fakeClaims{claimed: true}, Admission: &fakeAdmission{allowed: true}}
 	if err := processor.Process(context.Background(), message); err != nil {
 		t.Fatal(err)
 	}
@@ -115,7 +137,7 @@ func TestProcessorAcknowledgesPersistedHandoff(t *testing.T) {
 
 func TestProcessorRetriesUntilBackendHandoffIsDurable(t *testing.T) {
 	message := &fakeMessage{data: encodedAssignment(t)}
-	processor := Processor{TrustDomain: "ddupan.top", Accepter: &fakeAccepter{}, Claims: &fakeClaims{}, RetryDelay: 2 * time.Second}
+	processor := Processor{TrustDomain: "ddupan.top", Accepter: &fakeAccepter{}, Claims: &fakeClaims{}, Admission: &fakeAdmission{allowed: true}, RetryDelay: 2 * time.Second}
 	if err := processor.Process(context.Background(), message); err != nil {
 		t.Fatal(err)
 	}
@@ -126,10 +148,12 @@ func TestProcessorRetriesUntilBackendHandoffIsDurable(t *testing.T) {
 
 func TestProcessorRetriesBackendFailureAndTerminatesPoisonMessage(t *testing.T) {
 	retry := &fakeMessage{data: encodedAssignment(t)}
+	admission := &fakeAdmission{allowed: true}
 	processor := Processor{
 		TrustDomain: "ddupan.top",
 		Accepter:    &fakeAccepter{err: errors.New("backend unavailable")},
 		Claims:      &fakeClaims{},
+		Admission:   admission,
 		RetryDelay:  time.Minute,
 	}
 	if err := processor.Process(context.Background(), retry); err == nil {
@@ -138,6 +162,9 @@ func TestProcessorRetriesBackendFailureAndTerminatesPoisonMessage(t *testing.T)
 	if retry.nacked != time.Minute {
 		t.Fatalf("retry delay = %s", retry.nacked)
 	}
+	if admission.released != 1 {
+		t.Fatalf("released slots = %d", admission.released)
+	}
 
 	poison := &fakeMessage{data: []byte("not-json")}
 	if err := processor.Process(context.Background(), poison); err == nil {
@@ -148,6 +175,24 @@ func TestProcessorRetriesBackendFailureAndTerminatesPoisonMessage(t *testing.T)
 	}
 }
 
+func TestProcessorLeavesAssignmentPendingWhenBackendPoolIsFull(t *testing.T) {
+	message := &fakeMessage{data: encodedAssignment(t)}
+	accepter := &fakeAccepter{accepted: true}
+	processor := Processor{
+		TrustDomain: "ddupan.top",
+		Accepter:    accepter,
+		Claims:      &fakeClaims{},
+		Admission:   &fakeAdmission{},
+		RetryDelay:  3 * time.Second,
+	}
+	if err := processor.Process(context.Background(), message); err != nil {
+		t.Fatal(err)
+	}
+	if message.acked != 0 || message.nacked != 3*time.Second {
+		t.Fatalf("message = %#v", message)
+	}
+}
+
 type fakeConsumerManager struct{ config jetstream.ConsumerConfig }
 
 func (m *fakeConsumerManager) CreateOrUpdateConsumer(_ context.Context, _ string, config jetstream.ConsumerConfig) (jetstream.Consumer, error) {
@@ -160,7 +205,7 @@ func TestOpenConsumerUsesIndependentDurablePerBackend(t *testing.T) {
 	if _, err := OpenConsumer(context.Background(), manager, "CI_RUNNER", "ci.assignment", taskassignment.BackendPod, 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 {
+	if manager.config.Durable != "pod" || manager.config.FilterSubject != "ci.assignment.pod" || manager.config.AckPolicy != jetstream.AckExplicitPolicy || manager.config.MaxAckPending != 4 || manager.config.MaxDeliver != 1000 {
 		t.Fatalf("config = %#v", manager.config)
 	}
 }

internal/backendpool/pool.go

@@ -0,0 +1,50 @@
+// Package backendpool manages runtime capacity independently for each executor backend.
+package backendpool
+
+import "sync"
+
+type Pool struct {
+	mu       sync.Mutex
+	capacity int
+	active   map[string]struct{}
+}
+
+func New(capacity int) *Pool {
+	return &Pool{capacity: capacity, active: make(map[string]struct{})}
+}
+
+// Acquire reserves a backend slot without blocking. Redelivery of the same
+// assignment is idempotent and succeeds even while the pool is full.
+func (p *Pool) Acquire(assignmentID string) bool {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if _, exists := p.active[assignmentID]; exists {
+		return true
+	}
+	if assignmentID == "" || len(p.active) >= p.capacity {
+		return false
+	}
+	p.active[assignmentID] = struct{}{}
+	return true
+}
+
+func (p *Pool) Restore(assignmentID string) {
+	if assignmentID == "" {
+		return
+	}
+	p.mu.Lock()
+	p.active[assignmentID] = struct{}{}
+	p.mu.Unlock()
+}
+
+func (p *Pool) Release(assignmentID string) {
+	p.mu.Lock()
+	delete(p.active, assignmentID)
+	p.mu.Unlock()
+}
+
+func (p *Pool) Active() int {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	return len(p.active)
+}

internal/backendpool/pool_test.go

@@ -0,0 +1,26 @@
+package backendpool
+
+import "testing"
+
+func TestPoolSeparatesRuntimeCapacityFromDeliveries(t *testing.T) {
+	pool := New(2)
+	if !pool.Acquire("one") || !pool.Acquire("two") || pool.Acquire("three") {
+		t.Fatal("capacity was not enforced")
+	}
+	if !pool.Acquire("one") {
+		t.Fatal("redelivery must be idempotent")
+	}
+	pool.Release("one")
+	if !pool.Acquire("three") || pool.Active() != 2 {
+		t.Fatalf("active=%d", pool.Active())
+	}
+}
+
+func TestRestoreMayTemporarilyExceedReducedCapacity(t *testing.T) {
+	pool := New(1)
+	pool.Restore("one")
+	pool.Restore("two")
+	if pool.Active() != 2 || pool.Acquire("three") {
+		t.Fatalf("active=%d", pool.Active())
+	}
+}

internal/opensandboxbackend/backend.go

@@ -3,9 +3,13 @@ package opensandboxbackend
 
 import (
 	"context"
+	"encoding/base64"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"net/http"
+	"sort"
+	"strings"
 	"time"
 
 	opensandbox "github.com/alibaba/OpenSandbox/sdks/sandbox/go"
@@ -17,6 +21,8 @@ import (
 
 const assignmentMetadata = "ci.ddupan.top/assignment-id"
 const terminalMetadata = "ci.ddupan.top/terminal"
+const annotationsMetadataPrefix = "ci.ddupan.top/annotations-"
+const metadataValueLimit = 63
 
 type Lifecycle interface {
 	ListSandboxes(context.Context, opensandbox.ListOptions) (*opensandbox.ListSandboxesResponse, error)
@@ -123,7 +129,11 @@ func (b Backend) RecoverAssignments(ctx context.Context, trustDomain string) ([]
 		if sandbox.Metadata[terminalMetadata] == "true" {
 			continue
 		}
-		assignment, err := taskassignment.FromMetadata(sandbox.Metadata, sandbox.Metadata, trustDomain)
+		annotations, err := decodeAnnotations(sandbox.Metadata)
+		if err != nil {
+			return nil, fmt.Errorf("decode sandbox %s annotations: %w", sandbox.ID, err)
+		}
+		assignment, err := taskassignment.FromMetadata(sandbox.Metadata, annotations, trustDomain)
 		if err != nil {
 			return nil, fmt.Errorf("recover sandbox %s: %w", sandbox.ID, err)
 		}
@@ -169,8 +179,12 @@ func (b Backend) Create(ctx context.Context, assignment taskassignment.Assignmen
 	for key, value := range launch.Environment {
 		environment[key] = value
 	}
-	sandboxMetadata := clone(launch.Metadata.Annotations)
+	sandboxMetadata := clone(launch.Metadata.Labels)
-	for key, value := range launch.Metadata.Labels {
+	annotations, err := encodeAnnotations(launch.Metadata.Annotations)
+	if err != nil {
+		return nil, fmt.Errorf("encode sandbox annotations: %w", err)
+	}
+	for key, value := range annotations {
 		sandboxMetadata[key] = value
 	}
 	request := opensandbox.CreateSandboxRequest{
@@ -194,7 +208,11 @@ func (b Backend) BindIdentity(ctx context.Context, executor *taskworker.Executor
 	if err != nil {
 		return fmt.Errorf("verify sandbox identity metadata: %w", err)
 	}
-	if sandbox.Metadata["ci.ddupan.top/spiffe-id"] != identity.SPIFFEID {
+	annotations, err := decodeAnnotations(sandbox.Metadata)
+	if err != nil {
+		return fmt.Errorf("decode sandbox identity metadata: %w", err)
+	}
+	if annotations["ci.ddupan.top/spiffe-id"] != identity.SPIFFEID {
 		return fmt.Errorf("sandbox %s has inconsistent SPIFFE identity metadata", executor.Name)
 	}
 	return nil
@@ -243,3 +261,50 @@ func clone(source map[string]string) map[string]string {
 	}
 	return result
 }
+
+// OpenSandbox metadata follows Kubernetes label-value constraints, unlike Pod
+// annotations. Store the annotation map as deterministic URL-safe base64
+// chunks so repository paths and SPIFFE IDs remain lossless and recoverable.
+func encodeAnnotations(annotations map[string]string) (map[string]string, error) {
+	data, err := json.Marshal(annotations)
+	if err != nil {
+		return nil, err
+	}
+	encoded := base64.RawURLEncoding.EncodeToString(data)
+	result := make(map[string]string, (len(encoded)+metadataValueLimit-1)/metadataValueLimit)
+	for index := 0; len(encoded) > 0; index++ {
+		length := min(metadataValueLimit, len(encoded))
+		result[fmt.Sprintf("%s%03d", annotationsMetadataPrefix, index)] = encoded[:length]
+		encoded = encoded[length:]
+	}
+	return result, nil
+}
+
+func decodeAnnotations(metadata map[string]string) (map[string]string, error) {
+	keys := make([]string, 0)
+	for key := range metadata {
+		if strings.HasPrefix(key, annotationsMetadataPrefix) {
+			keys = append(keys, key)
+		}
+	}
+	if len(keys) == 0 {
+		return nil, errors.New("sandbox annotation metadata is missing")
+	}
+	sort.Strings(keys)
+	var encoded strings.Builder
+	for index, key := range keys {
+		if key != fmt.Sprintf("%s%03d", annotationsMetadataPrefix, index) {
+			return nil, errors.New("sandbox annotation metadata chunks are incomplete")
+		}
+		encoded.WriteString(metadata[key])
+	}
+	data, err := base64.RawURLEncoding.DecodeString(encoded.String())
+	if err != nil {
+		return nil, err
+	}
+	var annotations map[string]string
+	if err := json.Unmarshal(data, &annotations); err != nil {
+		return nil, err
+	}
+	return annotations, nil
+}

internal/opensandboxbackend/backend_test.go

@@ -31,7 +31,8 @@ func (f *fakeLifecycle) GetSandbox(_ context.Context, id string) (*opensandbox.S
 			return &item, nil
 		}
 	}
-	return &opensandbox.SandboxInfo{ID: id, Metadata: map[string]string{"ci.ddupan.top/spiffe-id": assignment().Identity.SPIFFEID}}, nil
+	metadata, _ := encodeAnnotations(map[string]string{"ci.ddupan.top/spiffe-id": assignment().Identity.SPIFFEID})
+	return &opensandbox.SandboxInfo{ID: id, Metadata: metadata}, nil
 }
 func (f *fakeLifecycle) PatchSandboxMetadata(_ context.Context, id string, patch opensandbox.MetadataPatch) (*opensandbox.SandboxInfo, error) {
 	for index := range f.items {
@@ -89,12 +90,38 @@ func TestCreateUsesPoolAndPersistsRecoveryMetadata(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if lifecycle.created.Extensions["poolRef"] != "ci-vm" || lifecycle.created.Metadata[assignmentMetadata] != assignment().ID || lifecycle.created.Env["CI_SPIFFE_ID"] != assignment().Identity.SPIFFEID || executor.Name != "sandbox-42" {
+	if lifecycle.created.Extensions["poolRef"] != "ci-vm" || lifecycle.created.Metadata[assignmentMetadata] != assignment().ID || lifecycle.created.Metadata["ci.ddupan.top/runner"] != "true" || lifecycle.created.Env["CI_SPIFFE_ID"] != assignment().Identity.SPIFFEID || executor.Name != "sandbox-42" {
 		t.Fatalf("request=%#v executor=%#v", lifecycle.created, executor)
 	}
 	if lifecycle.created.Env["CI_RUNNER_CAPABILITY"] != "capability" {
 		t.Fatalf("environment = %#v", lifecycle.created.Env)
 	}
+	annotations, err := decodeAnnotations(lifecycle.created.Metadata)
+	if err != nil || annotations["ci.ddupan.top/repository"] != "owner/repo" || annotations["ci.ddupan.top/spiffe-id"] != assignment().Identity.SPIFFEID {
+		t.Fatalf("annotations=%#v err=%v", annotations, err)
+	}
+	for _, value := range lifecycle.created.Metadata {
+		if len(value) > metadataValueLimit {
+			t.Fatalf("metadata value exceeds %d characters: %q", metadataValueLimit, value)
+		}
+	}
+}
+
+func TestAnnotationMetadataRoundTripPreservesSlashValues(t *testing.T) {
+	want := taskworker.BackendMetadata(assignment()).Annotations
+	encoded, err := encodeAnnotations(want)
+	if err != nil {
+		t.Fatal(err)
+	}
+	got, err := decodeAnnotations(encoded)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for key, value := range want {
+		if got[key] != value {
+			t.Fatalf("%s=%q, want %q", key, got[key], value)
+		}
+	}
 }
 
 func TestBindIdentityVerifiesPersistedMetadata(t *testing.T) {

internal/taskassignment/assignment.go

@@ -102,7 +102,7 @@ func backendFromTask(task *runnerv1.Task) (Backend, error) {
 		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))
+	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)
 	}

internal/taskassignment/assignment_test.go

@@ -28,6 +28,7 @@ func TestNewSelectsBackendFromRunsOn(t *testing.T) {
 	}{
 		{"[self-hosted, pod]", BackendPod},
 		{"[self-hosted, vm]", BackendVM},
+		{"[self-hosted, vm-dev]", BackendVM},
 	} {
 		assignment, err := New(task(t, test.labels), "ddupan.top")
 		if err != nil {

internal/taskscheduler/poller.go

@@ -4,8 +4,11 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"sync/atomic"
 	"time"
 
+	"golang.org/x/sync/errgroup"
+
 	runnerv1 "gitea.dev/actionslib/runner/v1"
 )
 
@@ -19,10 +22,12 @@ type PollerConfig struct {
 	Labels       []string
 	EmptyBackoff time.Duration
 	ErrorBackoff time.Duration
+	Capacity     int
 }
 
-// Poller is the scheduler component. Once Gitea assigns a task, it never
+// Poller is the scheduler component. Each fetcher keeps its assigned task
-// fetches another one until the current assignment is durably dispatched.
+// until that assignment is durably dispatched; all fetchers share one runner
+// declaration and a monotonic tasks version.
 type Poller struct {
 	Client    PollClient
 	Scheduler *Scheduler
@@ -49,9 +54,21 @@ func (p Poller) Run(ctx context.Context) error {
 	if errorBackoff <= 0 {
 		errorBackoff = 5 * time.Second
 	}
-	var tasksVersion int64
+	capacity := p.Config.Capacity
+	if capacity < 1 {
+		capacity = 1
+	}
+	var tasksVersion atomic.Int64
+	group, groupContext := errgroup.WithContext(ctx)
+	for range capacity {
+		group.Go(func() error { return p.runFetcher(groupContext, &tasksVersion, emptyBackoff, errorBackoff) })
+	}
+	return group.Wait()
+}
+
+func (p Poller) runFetcher(ctx context.Context, tasksVersion *atomic.Int64, emptyBackoff, errorBackoff time.Duration) error {
 	for {
-		response, err := p.Client.FetchTask(ctx, tasksVersion)
+		response, err := p.Client.FetchTask(ctx, tasksVersion.Load())
 		if err != nil {
 			if ctx.Err() != nil {
 				return nil
@@ -69,7 +86,7 @@ func (p Poller) Run(ctx context.Context) error {
 			}
 			continue
 		}
-		tasksVersion = response.GetTasksVersion()
+		storeMaximum(tasksVersion, response.GetTasksVersion())
 		task := response.GetTask()
 		if task == nil {
 			if !wait(ctx, emptyBackoff) {
@@ -93,6 +110,14 @@ func (p Poller) Run(ctx context.Context) error {
 	}
 }
 
+func storeMaximum(value *atomic.Int64, candidate int64) {
+	for current := value.Load(); candidate > current; current = value.Load() {
+		if value.CompareAndSwap(current, candidate) {
+			return
+		}
+	}
+}
+
 func (p Poller) report(err error) {
 	if p.OnError != nil {
 		p.OnError(err)

internal/taskscheduler/poller_test.go

@@ -115,3 +115,52 @@ func TestPollerRetriesAssignedTaskBeforeFetchingAnother(t *testing.T) {
 		t.Fatalf("dispatches=%d fetches-before-dispatch=%d declares=%d", dispatcher.calls, dispatcher.fetchesAtSuccess, client.declared)
 	}
 }
+
+type blockingPollClient struct {
+	mu       sync.Mutex
+	declared int
+	started  chan struct{}
+}
+
+func (c *blockingPollClient) Declare(context.Context, string, []string) error {
+	c.mu.Lock()
+	c.declared++
+	c.mu.Unlock()
+	return nil
+}
+
+func (c *blockingPollClient) FetchTask(ctx context.Context, _ int64) (*runnerv1.FetchTaskResponse, error) {
+	c.started <- struct{}{}
+	<-ctx.Done()
+	return nil, ctx.Err()
+}
+
+func TestPollerStartsConfiguredNumberOfFetchersAfterOneDeclare(t *testing.T) {
+	client := &blockingPollClient{started: make(chan struct{}, 3)}
+	poller := Poller{
+		Client:    client,
+		Scheduler: &Scheduler{TrustDomain: "ddupan.top", Dispatcher: &retryDispatcher{done: make(chan struct{})}},
+		Config: PollerConfig{
+			Version: "dev", Labels: []string{"self-hosted:host", "pod:host", "vm:host"}, Capacity: 3,
+		},
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	finished := make(chan error, 1)
+	go func() { finished <- poller.Run(ctx) }()
+	for range 3 {
+		select {
+		case <-client.started:
+		case <-time.After(time.Second):
+			t.Fatal("configured fetchers did not start")
+		}
+	}
+	cancel()
+	if err := <-finished; err != nil {
+		t.Fatal(err)
+	}
+	client.mu.Lock()
+	defer client.mu.Unlock()
+	if client.declared != 1 {
+		t.Fatalf("declares = %d", client.declared)
+	}
+}

internal/taskworker/worker.go

@@ -178,6 +178,7 @@ 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),