f - Update MPP completion condition in timeout check to match + leave comments

Author: alecchendev

lightning/src/ln/channelmanager.rs

@@ -3338,6 +3338,8 @@ where
 												_ => unreachable!(),
 											}
 										}
+										// The condition determining whether an MPP is complete must
+										// match exactly the condition used in `timer_tick_occurred`
 										if total_value >= msgs::MAX_VALUE_MSAT {
 											fail_htlc!(claimable_htlc, payment_hash);
 										} else if total_value - claimable_htlc.sender_intended_value >= $payment_data.total_msat {
@@ -3672,7 +3674,9 @@ where
 				if let OnionPayload::Invoice { .. } = htlcs[0].onion_payload {
 					// Check if we've received all the parts we need for an MPP (the value of the parts adds to total_msat).
 					// In this case we're not going to handle any timeouts of the parts here.
-					if htlcs[0].total_msat <= htlcs.iter().fold(0, |total, htlc| total + htlc.value) {
+					// This condition determining whether the MPP is complete here must match
+					// exactly the condition used in `process_pending_htlc_forwards`.
+					if htlcs[0].total_msat <= htlcs.iter().fold(0, |total, htlc| total + htlc.sender_intended_value) {
 						return true;
 					} else if htlcs.into_iter().any(|htlc| {
 						htlc.timer_ticks += 1;