fix: close expired worker snapshot streams

docs/api/control-plane.md

@@ -92,6 +92,11 @@ Gateway 接收完整快照时必须拒绝缺失、格式错误或已到期的 `v
 保存在本地不可变视图。该整体期限到达后，调度直接按无候选处理，不再使用旧视图
 发起新的上游连接，也不查询 Redis 或 PostgreSQL 补偿。
 
+Controller 只会下发尚未到期的完整快照，并在最近一次成功下发快照的
+`valid_until` 到达时结束 `WatchSnapshots` 流。Gateway 的会话调用方必须在流结束后
+按带 jitter 的有界退避重建 Register/Watch 会话；在新快照通过校验并原子替换前，
+旧视图仍按其整体有效期 fail-closed。
+
 Delta 声明 `base_version`。Worker 只有在本地版本恰好等于 base 且 checksum
 验证成功时才能应用；否则丢弃 Delta 并请求完整 Snapshot。构建在后台完成，
 热路径只读取一次原子指针。

docs/development/implementation-plan.md

@@ -214,8 +214,9 @@ WorkerControlPlane 现已接入 Controller 生命周期：Register、ACK 和 Run
 Snapshot 并保持连接；Gateway 已具备 Register/Watch/ACK/Runtime 会话协调组件。
 按 Worker 的可下发 ownership 索引已进入 Redis 原子脚本，并可构建无凭据引用的
 已归属 Proxy payload。Snapshot 签发与 session 匹配在同一 Redis Lua 操作中完成，
-重注册会清除旧引用，避免迟到 Stream 覆盖新 session。Routing payload、凭据分发、
-Gateway 命令与 Outcome 上报仍未实现。
+重注册会清除旧引用，避免迟到 Stream 覆盖新 session。Worker 服务端会在最近完整
+Snapshot 的 `valid_until` 到达时结束流，令 Gateway 调用方可按退避策略重建会话；
+Routing payload、凭据分发、Gateway 命令与 Outcome 上报仍未实现。
 
 已新增公用 `domain/activitypool` 契约及并发安全内存参考实现，Provider
 Reconciler 通过 `UpsertFetched` 写入带供应商 TTL 和分配安全余量的批次；已覆盖

docs/requirements/completion-audit.md

@@ -53,8 +53,9 @@
   Register/Watch/ACK/Runtime 会话协调已实现。Redis 以 Worker 可下发 ownership
   索引构建无凭据引用的已归属 Proxy payload，并以租约收紧可用期；Routing payload、
   凭据分发、Outcome 和 Checker 尚未闭环。Snapshot 签发在 Redis 中原子匹配当前
-  `session_id`，重注册会清除旧引用，迟到旧 Stream 不会覆盖新 session。Gateway 会
-  校验并执行 Snapshot 整体 `valid_until`，过期视图不再分配新 Proxy。
+  `session_id`，重注册会清除旧引用，迟到旧 Stream 不会覆盖新 session。Controller
+  在最近成功下发的 Snapshot `valid_until` 到达时关闭流，Gateway 会校验并执行
+  Snapshot 整体 `valid_until`，过期视图不再分配新 Proxy。
 - `PostgreSQL 管理面`：已定义 `adminstate` 事务 seam、并发安全 MemoryStore、
   公用契约、100 并发 Routing CAS、租约 Outbox 和只含六张管理表的 Schema；pgx
   Adapter 已在真实 PostgreSQL 18 上通过同一契约、迁移幂等、审计/Outbox

internal/controller/worker/grpc_handler.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"crypto/sha256"
 	"errors"
+	"time"
 
 	controlplanev1 "proxy-pool/gen/controlplane/v1"
 	"proxy-pool/internal/domain/workerruntime"
@@ -78,10 +79,17 @@ func (handler *GRPCHandler) WatchSnapshots(request *controlplanev1.WatchSnapshot
 	if err != nil {
 		return grpcError(err)
 	}
+	var expiryTimer *time.Timer
+	var expiry <-chan time.Time
+	defer func() {
+		stopSnapshotExpiryTimer(expiryTimer)
+	}()
 	for {
 		select {
 		case <-stream.Context().Done():
 			return stream.Context().Err()
+		case <-expiry:
+			return nil
 		case snapshot, ok := <-updates:
 			if !ok {
 				return nil
@@ -92,6 +100,7 @@ func (handler *GRPCHandler) WatchSnapshots(request *controlplanev1.WatchSnapshot
 			if err := stream.Send(&controlplanev1.SnapshotEnvelope{Payload: &controlplanev1.SnapshotEnvelope_Full{Full: snapshot}}); err != nil {
 				return err
 			}
+			expiryTimer, expiry = resetSnapshotExpiryTimer(expiryTimer, snapshot.GetValidUntil().AsTime())
 		}
 	}
 }
@@ -99,7 +108,8 @@ func (handler *GRPCHandler) WatchSnapshots(request *controlplanev1.WatchSnapshot
 func (handler *GRPCHandler) issueSnapshot(ctx context.Context, workerID, sessionID string, snapshot *controlplanev1.WorkerSnapshot) error {
 	if snapshot == nil || snapshot.GetVersion() == 0 || snapshot.GetOwnershipEpoch() == 0 || len(snapshot.GetChecksum()) != sha256.Size ||
 		snapshot.GetGeneratedAt() == nil || snapshot.GetGeneratedAt().CheckValid() != nil ||
-		snapshot.GetValidUntil() == nil || snapshot.GetValidUntil().CheckValid() != nil {
+		snapshot.GetValidUntil() == nil || snapshot.GetValidUntil().CheckValid() != nil ||
+		!snapshot.GetValidUntil().AsTime().After(time.Now().UTC()) {
 		return ErrInvalidCommand
 	}
 	var checksum [sha256.Size]byte
@@ -109,6 +119,37 @@ func (handler *GRPCHandler) issueSnapshot(ctx context.Context, workerID, session
 	})
 }
 
+func resetSnapshotExpiryTimer(timer *time.Timer, deadline time.Time) (*time.Timer, <-chan time.Time) {
+	delay := time.Until(deadline)
+	if delay <= 0 {
+		delay = time.Nanosecond
+	}
+	if timer == nil {
+		timer = time.NewTimer(delay)
+		return timer, timer.C
+	}
+	if !timer.Stop() {
+		select {
+		case <-timer.C:
+		default:
+		}
+	}
+	timer.Reset(delay)
+	return timer, timer.C
+}
+
+func stopSnapshotExpiryTimer(timer *time.Timer) {
+	if timer == nil {
+		return
+	}
+	if !timer.Stop() {
+		select {
+		case <-timer.C:
+		default:
+		}
+	}
+}
+
 func (handler *GRPCHandler) AcknowledgeSnapshot(ctx context.Context, request *controlplanev1.AcknowledgeSnapshotRequest) (*emptypb.Empty, error) {
 	if request == nil || handler == nil || handler.service == nil || handler.identity == nil {
 		return nil, grpcError(ErrInvalidCommand)

internal/controller/worker/grpc_handler_test.go

@@ -2,6 +2,7 @@ package worker
 
 import (
 	"context"
+	"io"
 	"net"
 	"testing"
 	"time"
@@ -90,6 +91,52 @@ func TestGRPCHandlerStreamsIssuedFullSnapshots(t *testing.T) {
 	}
 }
 
+func TestGRPCHandlerClosesSnapshotStreamAtValidityDeadline(t *testing.T) {
+	checksum := make([]byte, 32)
+	checksum[0] = 1
+	full := &controlplanev1.WorkerSnapshot{
+		Version: 3, OwnershipEpoch: 9, Checksum: checksum,
+		GeneratedAt: timestamppb.New(time.Now()), ValidUntil: timestamppb.New(time.Now().Add(100 * time.Millisecond)),
+	}
+	service := &grpcServiceStub{}
+	client, cleanup := grpcWorkerClient(t, service, allowIdentity{}, holdingSnapshotSource{snapshot: full})
+	defer cleanup()
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+	defer cancel()
+	stream, err := client.WatchSnapshots(ctx, &controlplanev1.WatchSnapshotsRequest{WorkerId: "worker-a", SessionId: "session-a"})
+	if err != nil {
+		t.Fatalf("WatchSnapshots(): %v", err)
+	}
+	if received, err := stream.Recv(); err != nil || received.GetFull().GetVersion() != 3 {
+		t.Fatalf("first Recv() = %+v, %v", received, err)
+	}
+	if _, err := stream.Recv(); err != io.EOF {
+		t.Fatalf("Recv(after validity deadline) error = %v, want EOF", err)
+	}
+}
+
+func TestGRPCHandlerRejectsExpiredSnapshot(t *testing.T) {
+	checksum := make([]byte, 32)
+	checksum[0] = 1
+	full := &controlplanev1.WorkerSnapshot{
+		Version: 3, OwnershipEpoch: 9, Checksum: checksum,
+		GeneratedAt: timestamppb.New(time.Now().Add(-time.Minute)), ValidUntil: timestamppb.New(time.Now().Add(-time.Second)),
+	}
+	service := &grpcServiceStub{}
+	client, cleanup := grpcWorkerClient(t, service, allowIdentity{}, snapshotSourceStub{snapshots: []*controlplanev1.WorkerSnapshot{full}})
+	defer cleanup()
+	stream, err := client.WatchSnapshots(context.Background(), &controlplanev1.WatchSnapshotsRequest{WorkerId: "worker-a", SessionId: "session-a"})
+	if err != nil {
+		t.Fatalf("WatchSnapshots(): %v", err)
+	}
+	if _, err := stream.Recv(); status.Code(err) != codes.InvalidArgument {
+		t.Fatalf("Recv() code = %s, want InvalidArgument; error=%v", status.Code(err), err)
+	}
+	if service.issued.Version != 0 {
+		t.Fatalf("expired snapshot was issued: %+v", service.issued)
+	}
+}
+
 func TestGRPCHandlerDoesNotDeliverSnapshotWhenSessionBecomesStale(t *testing.T) {
 	checksum := make([]byte, 32)
 	checksum[0] = 1
@@ -157,6 +204,16 @@ type snapshotSourceStub struct {
 	snapshots []*controlplanev1.WorkerSnapshot
 }
 
+type holdingSnapshotSource struct {
+	snapshot *controlplanev1.WorkerSnapshot
+}
+
+func (source holdingSnapshotSource) Watch(_ context.Context, _ SnapshotWatchRequest) (<-chan *controlplanev1.WorkerSnapshot, error) {
+	updates := make(chan *controlplanev1.WorkerSnapshot, 1)
+	updates <- source.snapshot
+	return updates, nil
+}
+
 func (source snapshotSourceStub) Watch(_ context.Context, _ SnapshotWatchRequest) (<-chan *controlplanev1.WorkerSnapshot, error) {
 	updates := make(chan *controlplanev1.WorkerSnapshot, len(source.snapshots))
 	for _, snapshot := range source.snapshots {