The robots exclusion protocol expresses crawl preferences. Signal Vault permits its public archive while disallowing the canary directory for every declared crawler group. A normal visible link also exposes the canary download as part of the experiment.
A canary request is only an observation. A human may click it, a user may direct a fetch, or a client may have older crawl rules. It is not by itself proof of malicious behavior. The response contains a small, labelled research fixture and no private records.
Reference: Robots Exclusion Protocol (RFC 9309)