D025 - pros-link takes tracing and nothing else

Status: decided Date: 2026-09-26

pros-link's one dependency is tracing, without attributes. No runtime, TLS stack or serialisation framework; hashing and manifests live in pros-core. Each further dependency is argued for individually in the manifest. A refused port logs at debug and a per-service probe at trace.

Why: obSCEne takes this crate and holds a deliberate dependency list. tracing costs a few packages and no proc-macro, max_level_off compiles it away for a consumer that wants nothing, and without it the transport cannot say why a connection failed. A shut port is an ordinary answer, so a warning would fire on a successful check.

Rejected:

• No dependencies at all: the transport cannot report what it is doing.
• tracing with attributes: a proc-macro chain for #[instrument], which nothing uses.