_Originally posted by @S3RK in https://github.com/bitcoin/bitcoin/pull/24984#pullrequestreview-952900468_

> With current implementation we don't save the rescan progress and on the next load we will have to start from scratch. Is it possible to save the last processed blocked at shutdown?

It would be nice if wallet code would call `WriteBestBlock` and save the last scan position if it is interrupted during a sync. This could be implemented by trying to save the scan position during the shutdown, or by just periodically saving the scan position after an interval, similar to indexing code which saves sync position once every 30 seconds:

https://github.com/bitcoin/bitcoin/blob/f0a834e2f10a0aa60c7cc76e9f3eb090168a32e5/src/index/base.cpp#L170-L175
Mutex m_unlock_mutex;
    bool Unlock(const SecureString& strWalletPassphrase, bool accept_no_keys = false);
    bool ChangeWalletPassphrase(const SecureString& strOldWalletPassphrase, const SecureString& strNewWalletPassphrase);
    bool EncryptWallet(const SecureString& strWalletPassphrase);
    void GetKeyBirthTimes(std::map<CKeyID, int64_t> &mapKeyBirth) const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
    unsigned int ComputeTimeSmart(const CWalletTx& wtx, bool rescanning_old_block) const;
    /**
     * Increment the next transaction order id
     * @return next transaction order id
     */
    int64_t IncOrderPosNext(WalletBatch *batch = nullptr) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
    DBErrors ReorderTransactions();
    void MarkDirty();
    
    
    
    
    
    
    using UpdateWalletTxFn = std::function<bool(CWalletTx& wtx, bool new_tx)>;
    CWalletTx* AddToWallet(CTransactionRef tx, const TxState& state, const UpdateWalletTxFn& update_wtx=nullptr, bool fFlushOnClose=true, bool rescanning_old_block = false);
    bool LoadToWallet(const uint256& hash, const UpdateWalletTxFn& fill_wtx) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
    void transactionAddedToMempool(const CTransactionRef& tx, uint64_t mempool_sequence) override;
    void blockConnected(const CBlock& block, int height) override;
    void blockDisconnected(const CBlock& block, int height) override;
    void updatedBlockTip() override;
    int64_t RescanFromTime(int64_t startTime, const WalletRescanReserver& reserver, bool update);
    struct ScanResult {
        enum { SUCCESS, FAILURE, USER_ABORT } status = SUCCESS;