Interface ScanResult

Per-handler discovery failures. Non-empty implies truncatedAt is set.

Highest HD index at which any handler confirmed a contract (-1 if none), including hits past ScanResult.truncatedAt. Safe to record unconditionally: the HD watermark it feeds is a monotonic max over a scan that always restarts at 0, so it cannot skip an index — while withholding it risks re-issuing a funded index as a fresh receive address.

First index a handler failed at, making it indeterminate — neither a hit nor a confirmed miss. The scan stops there, so indices >= truncatedAt are unverified and the caller must retry (scanning is idempotent). undefined when the scan closed a genuine gap.