Speed up wallet synchronization, especially re-syncs of large wallets:
- Incremental address discovery: known indices from the previous sync
(NextReceiveIndex/NextChangeIndex) are fetched in a single parallel
burst instead of sequential gap-limit rounds, cutting round-trips from
O(used/gapLimit) to ~O(1). Receive and change chains scan in parallel.
- Merge tx download and Merkle verification into one parallel phase
(no barrier between them); the per-call semaphore is dropped in favor
of the transport-level in-flight gate.
- Persist verified block headers (SyncCache.BlockHeaders, height -> hex):
immutable once stored, so blockchain.block.header round-trips for
already-verified proofs are eliminated on later syncs.
- RetryOnBusyAsync with exponential backoff around server calls, treating
-101/-102 and "server busy"/"excessive resource usage" as transient.
Wire the new PreloadCaches/ExportCaches signatures through the desktop
view model and the CLI sync command.
davide
5ff2075a45