f - Document the single-broadcast assumption for funding tracking

LDK calls broadcast_transactions once per signed funding or splice tx
today. Record that assumption and note what would need to change if
upstream starts rebroadcasting unconfirmed funding or splice
transactions.

No behavior change.

Generated with assistance from Claude Code.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: jkczyz

src/wallet/mod.rs

@@ -1715,6 +1715,12 @@ impl Wallet {
 		Ok(new_txid)
 	}
 
+	// TODO: `classify_funding` and `classify_splice` assume they are invoked once per
+	// transaction. LDK currently calls `broadcast_transactions` exactly once per signed
+	// funding or splice tx, so the assumption holds. If upstream adds rebroadcasting of
+	// unconfirmed funding/splice txs, add idempotency guards (e.g. skip when the txid is
+	// already tracked via `find_payment_by_txid`, and broaden the "last candidate" check
+	// in `classify_splice` to "any candidate").
 	pub(crate) fn classify_broadcast(
 		&self, tx: &Transaction, tx_type: &TransactionType,
 	) -> Result<(), Error> {