With proof of work skipped, chaining headers from a checkpoint up to a
transaction's block proves nothing: a server can fabricate a header and
fake headers after a real checkpoint. The header must now hash-chain up to
the nearest checkpoint at or above its height, whose hash is hardcoded.
This also anchors heights below the first checkpoint. The cached anchor
state is renamed AnchoredDownTo and caches without it are re-verified
once. Blocks above the newest checkpoint remain a documented limit.
See ADR 0040.
Empty header range during checkpoint anchoring, send-all limits, SyncCache
roundtrip, corrupted config, derivation edge cases, spendability
boundaries, unit formatting, loader errors, in-flight cap, disposal under
load and wallet-lock contention. Also raises the synchronizer partial-result
timeouts so they hold under load.
davide