Merge pull request #157 from tnull/2022-08-improve-confirmable-doc

Improve 'Confirmed Transactions' section

Author: jkczyz

docs/blockchain_data/confirmed_transactions.md

@@ -4,20 +4,29 @@ Up until this point, we've explored how to notify LDK of chain activity using
 blocks. But what if you're sourcing chain activity from a place that doesn't
 provide a block-centric interface, like Electrum?
 
-LDK has a `chain::Confirm` interface to support this use case, analogous to the
-block-oriented `chain::Listen` interface which we've been using up until now.
-With this alternative approach, you still need to give LDK block headers, but
-only for blocks containing transactions of interest. These are identified by
-`chain::Filter` as before. You also need to notify LDK of any transactions with
-insufficient confirmation that have been reorganized out of the chain. Use the
-`transactions_confirmed` and `transaction_unconfirmed` methods, respectively.
+LDK's `ChannelManager` and `ChainMonitor` implement a `chain::Confirm` interface to support this
+use case, analogous to the block-oriented `chain::Listen` interface which we've been using up until
+now. With this alternative approach, you still need to give LDK information about chain activity,
+but only for transactions of interest. To this end, you must call `Confirm::transactions_confirmed`
+when any transactions identified by `chain::Filter`'s `register_tx`/`register_output` methods are
+confirmed.
 
-Additionally, you must notify LDK whenever a new chain tip is available using
-the `best_block_updated` method. See the documentation for a full picture of how
-this interface is intended to be used.
+You also need to notify LDK of any transactions with insufficient confirmations
+that have been reorganized out of the chain. Transactions that need to be monitored for such
+reorganization are returned by `Confirm::get_relevant_txids`. If any of these transactions become
+unconfirmed, you must call `Confirm::transaction_unconfirmed`.
+
+Lastly, you must notify LDK whenever a new chain tip is available using
+the `Confirm::best_block_updated` method. See the documentation for a full
+picture of how this interface is intended to be used.
+
+::: tip Note
+Note that the described methods of `Confirm` must be called both on the
+`ChannelManager` *and* the `ChainMonitor`.
+:::
 
 ::: tip Note
 Be advised that `chain::Confirm` is a less mature interface than
-`chain::Listen`. As such, there is not yet a utility like `lightning-block-sync`
-to use for interacting with clients like Electrum.
+`chain::Listen`. As such, there is not yet a utility like
+`lightning-block-sync` to use for interacting with clients like Electrum.
 :::