Cross-chain hub future works

[doitian]

• [ ] 1. Persistent and tracking restoration. After restart, check the missing events for the active orders and restore the tracking workers.
• [x] 2. Support SHA256 hash in the contract. Allow negotiating the hash algorithm when openning the channel. #105
• [ ] 3. Resolve the performance issue that one HTTP connection is required for each active ReceiveBTC order to track the incoming HTLC in LND. See https://github.com/lightningnetwork/lnd/issues/3120

From #46

[doitian]

In issue #46, a workaround is implemented for the second action item. When the preimage is submitted through RemoveTlc, both the blake2b and sha256 algorithms are attempted.

However, it is important to note that the lock contract has not been updated. Therefore, if a dispute arises, the saved sha256 preimage cannot be utilized to claim the HTLC outputs.

As an alternative solution, it is suggested to configure the hash algorithm either when opening a channel or when adding a tlc. The lock contract must update to accept sha256 preimage as well.