[Bug]: XPC peer validation uses non-public API xpc_dictionary_get_audit_token, blocking App Store redistribution

[devops-thiago]

I have done the following

• I have searched the existing issues
• If possible, I've reproduced the issue using the 'main' branch of this project

Steps to reproduce

1. Build the project (main, abff418).
2. nm -u bin/container-apiserver | grep audit_token

Output:

_xpc_dictionary_get_audit_token

The concrete consequence: we redistribute the engine inside a Mac App Store app (re-signed under our own identity), and App Store Connect rejected the upload with:

The app uses or references the following non-public or deprecated APIs:
• _xpc_dictionary_get_audit_token
Revise the binary and remove all references to any non-public or deprecated APIs.

Problem description

#896 added same-EUID validation of XPC peers by reading each message's audit token. xpc_dictionary_get_audit_token is not in the public XPC headers — the CAuditToken target exists solely to re-declare its prototype, which is itself the tell.

The check's purpose (client EUID == server EUID) is fully served by public API: for a launchd Mach service, every peer arrives on its own connection, so the connection's credentials and the message sender's are the same identity, and xpc_connection_get_euid is the documented way to read them.

We run this replacement in production: same enforcement, and the CAuditToken shim target can be deleted entirely. It also unblocks anyone embedding these binaries in an App Store submission. Happy to open a PR.

Environment

• OS: macOS 26.6 (25G72)
• Xcode: 26.6 (17F113)
• Container: 1.2.0 (present unchanged on main at abff418)

Code of Conduct

• I agree to follow this project's Code of Conduct