The backend `sync` command is a blocking, uninterruptible full chain scan (do_sync(true);
does not honor the shutdown flag), and balance/list block until synced. Previously
startSync() ran on the main thread (would freeze wallet creation) and the worker could
block, making the destructor join() hang at shutdown.
Redesign:
- bridge is now std::shared_ptr<LiteClientBridge>, shared with a detached sync thread so
detaching is safe and litelib_shutdown isn't called while a running sync still holds the
bridge; the controller's own ref prevents premature shutdown during normal operation.
- startSync() launches the blocking `sync` on a detached thread (non-blocking; never joined).
- refreshModel() gates on syncDone_: while syncing it publishes syncstatus progress only;
once synced it does the full balance/addresses/list refresh (now fast).
- destructor joins only the fast poll worker and detaches the sync thread -> no hang.
- syncComplete() accessor added.
Tests (deterministic, via a blocking-sync fake; counters made atomic for the detached
thread): testLiteWalletControllerShutdownDoesNotHangDuringSync (destructor returns <1.5s
with sync blocked); refresh/worker tests wait for syncComplete()/a balance-bearing model.
Stable across repeated runs; lite+backend and full-node apps build clean.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>