An Esri or keyless terrain attempt that never settled kept the single-flight
retry open forever, so neither provider was retried again. Each attempt now
counts as failed after 60 seconds and the retry backs off as usual; its
signal is aborted, and a provider that lands after the deadline is released
rather than installed or cached.
CURRENT-STATE now says only the construction fallback to OSM is retried, not
the switch made after repeated Esri tile failures.