AutographLogger

Sink for the library's own diagnostic messages — a delivery that failed, or an event dropped because it did not validate. Set one on AutographConfig.logger to route these into your app's logging framework (Logcat, os_log, Timber, …) or to silence them; the default prints to the console, matching the library's historical behavior.

These are operational diagnostics about Autograph itself, not analytics events — they never reach a transport. A message is a single human-readable line, already prefixed with Autograph:. Keep an implementation cheap and thread-safe: it is called both on the caller's thread (when an event is dropped for failing validation) and on the stamping/delivery dispatcher (when a delivery fails). It need not be non-throwing — an exception it raises is swallowed, so a buggy logger can no more crash the app than a buggy EventValidator can — but the diagnostic is then simply lost.

This is a caller-implemented SPI (ADR 0001 §2c): a future capability that needs more than a line of text — a severity level, a structured payload — is added as a separate optional interface the core probes with is, never as a new method here, so an existing lambda implementor keeps working.