Keep the comment as it may be useful in the future.

Signed-off-by: Sasha Bogicevic <[email protected]>

Author: v0d1ch

hydra-node/src/Hydra/HeadLogic.hs

@@ -323,6 +323,15 @@ onOpenNetworkReqTx env ledger st ttl tx =
         | ttl > 0 ->
             wait (WaitOnNotApplicableTx err)
         | otherwise ->
+            -- XXX: We are removing invalid txs from allTxs here to
+            -- prevent them piling up infinitely. However, this is not really
+            -- covered by the spec and this could be problematic in case of
+            -- conflicting transactions paired with network latency and/or
+            -- message resubmission. For example: Assume tx2 depends on tx1, but
+            -- only tx2 is seen by a participant and eventually times out
+            -- because of network latency when receiving tx1. The leader,
+            -- however, saw both as valid and requests a snapshot including
+            -- both. This is a valid request and it could make the head stuck.
             newState TxInvalid{headId, utxo = localUTxO, transaction = tx, validationError = err}
 
   maybeRequestSnapshot nextSn outcome =