split container slot reconciliation

AGENTS_CHANGELOG.md

@@ -191,5 +191,6 @@
 
 - daemon server 将请求读取、进度回调、更新/重启分派、诊断分派拆开，保留协议错误文本与响应行为。
 - `runServe` 将 native/container 运行时构建与资源关闭拆出，避免入口函数承担全部分支。
+- 容器槽位现场核对拆为容器检查、已提交部署校验和活动槽位选择，减少单函数分支嵌套。
 
 验证：`GOCACHE=/tmp/yms-go-cache go test ./...`、`git diff --check` 通过。

internal/backendupdate/container.go

@@ -337,40 +337,19 @@ func (u *Updater) resolveContainerSlots(
 	if err != nil {
 		return 0, deploymentconfig.BackendSlot{}, "", err
 	}
-	active, activeErr := u.engine.InspectContainer(ctx, activeSlot.ContainerName)
-	if activeErr != nil && !errors.Is(activeErr, containerengine.ErrNotFound) {
-		return 0, deploymentconfig.BackendSlot{}, "", fmt.Errorf("inspect active backend container %s: %w", activeSlot.ContainerName, activeErr)
+	active, activeFound, err := u.inspectSlotContainer(ctx, activeSlot.ContainerName, "active")
+	if err != nil {
+		return 0, deploymentconfig.BackendSlot{}, "", err
 	}
-	inactive, inactiveErr := u.engine.InspectContainer(ctx, inactiveSlot.ContainerName)
-	if inactiveErr != nil && !errors.Is(inactiveErr, containerengine.ErrNotFound) {
-		return 0, deploymentconfig.BackendSlot{}, "", fmt.Errorf("inspect inactive backend container %s: %w", inactiveSlot.ContainerName, inactiveErr)
+	inactive, inactiveFound, err := u.inspectSlotContainer(ctx, inactiveSlot.ContainerName, "inactive")
+	if err != nil {
+		return 0, deploymentconfig.BackendSlot{}, "", err
 	}
-	activeFound := activeErr == nil
-	inactiveFound := inactiveErr == nil
-
-	if hasDeployment {
-		if deployment.ActivePort != activePort {
-			return 0, deploymentconfig.BackendSlot{}, "", fmt.Errorf("committed backend container port %d does not match gateway active port %d", deployment.ActivePort, activePort)
-		}
-		if deployment.ContainerName != activeSlot.ContainerName {
-			return 0, deploymentconfig.BackendSlot{}, "", fmt.Errorf("committed backend container %s does not match gateway slot container %s", deployment.ContainerName, activeSlot.ContainerName)
-		}
-		if !activeFound {
-			return 0, deploymentconfig.BackendSlot{}, "", fmt.Errorf("committed active backend container %s is missing", activeSlot.ContainerName)
-		}
-		if active.ID != deployment.ContainerID {
-			return 0, deploymentconfig.BackendSlot{}, "", fmt.Errorf("active backend container %s identity does not match committed deployment", activeSlot.ContainerName)
-		}
+	if err := validateCommittedContainer(deployment, activePort, activeSlot, active, activeFound, hasDeployment); err != nil {
+		return 0, deploymentconfig.BackendSlot{}, "", err
 	}
-
 	if activeFound {
-		if !active.Running || active.Dead {
-			return 0, deploymentconfig.BackendSlot{}, "", fmt.Errorf("active backend container %s is not running", activeSlot.ContainerName)
-		}
-		if inactiveFound && inactive.Running && !inactive.Dead {
-			return 0, deploymentconfig.BackendSlot{}, "", fmt.Errorf("inactive backend container %s is unexpectedly running", inactiveSlot.ContainerName)
-		}
-		return inactivePort, inactiveSlot, activeSlot.ContainerName, nil
+		return selectRunningContainerSlot(inactivePort, activeSlot, inactiveSlot, active, inactive, inactiveFound)
 	}
 	if hasHistory {
 		return 0, deploymentconfig.BackendSlot{}, "", fmt.Errorf("active backend container %s is missing on a server with committed backend container transaction history", activeSlot.ContainerName)
@@ -381,6 +360,46 @@ func (u *Updater) resolveContainerSlots(
 	return inactivePort, inactiveSlot, "", nil
 }
 
+func (u *Updater) inspectSlotContainer(ctx context.Context, name string, role string) (containerengine.Container, bool, error) {
+	container, err := u.engine.InspectContainer(ctx, name)
+	if errors.Is(err, containerengine.ErrNotFound) {
+		return containerengine.Container{}, false, nil
+	}
+	if err != nil {
+		return containerengine.Container{}, false, fmt.Errorf("inspect %s backend container %s: %w", role, name, err)
+	}
+	return container, true, nil
+}
+
+func validateCommittedContainer(deployment transaction.BackendContainerDeployment, activePort int, activeSlot deploymentconfig.BackendSlot, active containerengine.Container, found bool, hasDeployment bool) error {
+	if !hasDeployment {
+		return nil
+	}
+	if deployment.ActivePort != activePort {
+		return fmt.Errorf("committed backend container port %d does not match gateway active port %d", deployment.ActivePort, activePort)
+	}
+	if deployment.ContainerName != activeSlot.ContainerName {
+		return fmt.Errorf("committed backend container %s does not match gateway slot container %s", deployment.ContainerName, activeSlot.ContainerName)
+	}
+	if !found {
+		return fmt.Errorf("committed active backend container %s is missing", activeSlot.ContainerName)
+	}
+	if active.ID != deployment.ContainerID {
+		return fmt.Errorf("active backend container %s identity does not match committed deployment", activeSlot.ContainerName)
+	}
+	return nil
+}
+
+func selectRunningContainerSlot(inactivePort int, activeSlot, inactiveSlot deploymentconfig.BackendSlot, active, inactive containerengine.Container, inactiveFound bool) (int, deploymentconfig.BackendSlot, string, error) {
+	if !active.Running || active.Dead {
+		return 0, deploymentconfig.BackendSlot{}, "", fmt.Errorf("active backend container %s is not running", activeSlot.ContainerName)
+	}
+	if inactiveFound && inactive.Running && !inactive.Dead {
+		return 0, deploymentconfig.BackendSlot{}, "", fmt.Errorf("inactive backend container %s is unexpectedly running", inactiveSlot.ContainerName)
+	}
+	return inactivePort, inactiveSlot, activeSlot.ContainerName, nil
+}
+
 // resolvedImage 拉取并解析后得到的镜像信息。
 type resolvedImage struct {
 	// ImmutableReference 带摘要的不可变镜像引用。