The set of targets that should be scanned is built where the set that was
scanned is already known: in the existing exporter. Anything else needs the
same derivation twice, and two derivations are two truths. That also settles
where the coverage metric comes from.
The AAR of 2026-08-01 decided one thing outright. Its third finding says a
stale-scan rule cannot report an image that never scanned, because no series
exists to hang the expression on. A coverage figure built from existing series
is therefore blind to exactly the gap it is meant to show, so it has to come
from the desired set instead.
Two prices are written down rather than discovered later: a target that leaves
the set must lose its report, or an image no one runs keeps reporting; and more
targets mean more messages, roughly 65 instead of 29 per round, which Gate 5
has to measure since the reporting path itself is out of scope.
ADR-0026 generalises it — derive targets, never maintain them — with the
condition that makes it safe: a derivation that fails looks like full coverage,
not like an outage, so its freshness is itself alerted.
Thore Cimbal
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