Supported receiver-confinement guarantee for anonymous XPC connections on macOS 27.0.1

I’m assessing whether the public C XPC APIs provide the recipient guarantee needed for a local security boundary.

The proposed path uses a dedicated anonymous listener, a transferred xpc_endpoint_t, and xpc_connection_create_from_endpoint. Before releasing protected data, I need to establish which process occurrence can receive it and whether that binding continues to hold through delivery. Here, “process occurrence” means one running instance, including protection against confusing it with a later instance that reuses its PID.

The target reports macOS 27.0.1 (26A434), Darwin 27.0.0, arm64, and xnu-13432.1.9~1/RELEASE_ARM64_T6000. The selected Command Line Tools SDK reports macOS 27.0, SDK build 26A425. These are read-only inventory results; I have not run an XPC prototype for this question.

Is there a supported public API contract that lets the sending application, or a separately authorized local verifier, establish before protected data becomes accessible that this connection’s actual receiver is the authenticated process occurrence and remains confined to it for that send?

I specifically need to understand whether that guarantee covers endpoint copying or forwarding, repeated or concurrent connections created from one endpoint, process replacement, queued messages, and replies or access-capable attachments. I am asking about the selected C connection API; I do not assume equivalent behavior across the C and Swift session APIs.

If a supported mechanism exists, which APIs, OS versions, privileges or entitlements are required, and where is the guarantee documented? If the public API does not expose this guarantee, a clear statement of that limit would help me choose an appropriate transport boundary.

The distinction I need to resolve is between authenticating a peer at one point and ensuring that protected outgoing data reaches only that same process occurrence. I am seeking the supported security contract, without requesting access to private implementation details.