Fix container system status false negative under a Seatbelt sandbox. (#2316)

- `launchctl list` does not work as expected in the sandbox.
- Probe with `launchctl print <domain>/<label>` instead,
  which launchd does allow a sandboxed process, and key
  off exit codes: 0 means registered, 113 (ENOSERVICE)
  means not registered, and anything else is an error rather
  than being mistranslated into a negative.
- The probe is advisory in `system status`, so an indeterminate
  answer falls through to the XPC health check, whose success 
  is authoritative.

Signed-off-by: Renlord Yang <renlord@apple.com>

Sources/ContainerCommands/System/SystemStatus.swift

@@ -42,7 +42,8 @@ extension Application {
         public init() {}
 
         public func run() async throws {
-            let isRegistered = try ServiceManager.isRegistered(fullServiceLabel: "\(prefix)apiserver")
+            let domain = try ServiceManager.getDomainString()
+            let isRegistered = (try? ServiceManager.isRegistered(fullServiceLabel: "\(domain)/\(prefix)apiserver")) ?? true
             if !isRegistered {
                 try Output.render(payload: StatusPayload(status: "unregistered"), format: format) {
                     "apiserver is not running and not registered with launchd"

Sources/ContainerPlugin/ServiceManager.swift

@@ -18,6 +18,10 @@ import ContainerizationError
 import Foundation
 
 public struct ServiceManager {
+    enum LaunchctlStatus {
+        static let noSuchService: Int32 = 113
+    }
+
     private static func runLaunchctlCommand(args: [String]) throws -> Int32 {
         let launchctl = Foundation.Process()
         launchctl.executableURL = URL(fileURLWithPath: "/bin/launchctl")
@@ -94,8 +98,40 @@ public struct ServiceManager {
 
     /// Check if a service has been registered or not.
     public static func isRegistered(fullServiceLabel label: String) throws -> Bool {
-        let exitStatus = try runLaunchctlCommand(args: ["list", label])
-        return exitStatus == 0
+        let result = try runLaunchctlPrint(target: label)
+        return try Self.interpretPrintStatus(result.status, target: label, standardError: result.standardError)
+    }
+
+    private static func runLaunchctlPrint(target: String) throws -> (status: Int32, standardError: String) {
+        let launchctl = Foundation.Process()
+        launchctl.executableURL = URL(fileURLWithPath: "/bin/launchctl")
+        launchctl.arguments = ["print", target]
+
+        let stderrPipe = Pipe()
+        launchctl.standardOutput = FileHandle.nullDevice
+        launchctl.standardError = stderrPipe
+
+        try launchctl.run()
+        let errorData = stderrPipe.fileHandleForReading.readDataToEndOfFile()
+        launchctl.waitUntilExit()
+
+        return (launchctl.terminationStatus, String(decoding: errorData, as: UTF8.self))
+    }
+
+    static func interpretPrintStatus(_ status: Int32, target: String = "", standardError: String = "") throws -> Bool {
+        switch status {
+        case 0:
+            return true
+        case LaunchctlStatus.noSuchService:
+            return false
+        default:
+            var message = "command `launchctl print \(target)` failed with status \(status)"
+            let details = standardError.trimmingCharacters(in: .whitespacesAndNewlines)
+            if !details.isEmpty {
+                message += ", message: \(details)"
+            }
+            throw ContainerizationError(.internalError, message: message)
+        }
     }
 
     private static func getLaunchdSessionType() throws -> String {

Tests/ContainerPluginTests/ServiceManagerTests.swift

@@ -0,0 +1,55 @@
+//===----------------------------------------------------------------------===//
+// Copyright © 2026 Apple Inc. and the container project authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//===----------------------------------------------------------------------===//
+
+import Foundation
+import Testing
+
+@testable import ContainerPlugin
+
+struct ServiceManagerTests {
+    @Test
+    func testInterpretPrintStatusSuccessMeansRegistered() throws {
+        #expect(try ServiceManager.interpretPrintStatus(0))
+    }
+
+    @Test
+    func testInterpretPrintStatusNoSuchServiceMeansUnregistered() throws {
+        #expect(try !ServiceManager.interpretPrintStatus(ServiceManager.LaunchctlStatus.noSuchService))
+    }
+
+    @Test
+    func testInterpretPrintStatusUnexpectedStatusThrows() throws {
+        let statuses: [Int32] = [1, 3, 64, 112]
+        for status in statuses {
+            #expect {
+                _ = try ServiceManager.interpretPrintStatus(
+                    status,
+                    target: "gui/501/com.apple.container.apiserver",
+                    standardError: "marker"
+                )
+            } throws: { error in
+                "\(error)".contains("status \(status), message: marker")
+            }
+        }
+    }
+
+    @Test
+    func testIsRegisteredUnknownLabel() throws {
+        let domain = try ServiceManager.getDomainString()
+        let label = "\(domain)/com.apple.container.bogus-\(UUID().uuidString)"
+        #expect(try !ServiceManager.isRegistered(fullServiceLabel: label))
+    }
+}