tapfreighter: provide package response in SendStateWaitTxConf

Rename deliverTxBroadcastResp to deliverOutboundPkgResp and execute it
in SendStateWaitTxConf instead of SendStateBroadcast. This change allows
the RequestShipment caller to unblock when skipping the anchor
transaction broadcast and proceeding directly to tx confirmation wait.

Author: ffranr

tapfreighter/chain_porter.go

@@ -1558,17 +1558,19 @@ func (p *ChainPorter) stateStep(currentPkg sendPackage) (*sendPackage, error) {
 				"transaction %v: %w", txHash, err)
 		}
 
-		// With the transaction broadcast, we'll deliver a
-		// notification via the transaction broadcast response channel.
-		currentPkg.deliverTxBroadcastResp()
-
 		// Set send state to the next state to evaluate.
 		currentPkg.SendState = SendStateWaitTxConf
 		return &currentPkg, nil
 
 	// At this point, transaction broadcast is complete. We go on to wait
 	// for the transfer transaction to confirm on-chain.
 	case SendStateWaitTxConf:
+		// The state machine now transitions to waiting for the transfer
+		// transaction to be confirmed on-chain. Before entering this
+		// state, we return the outbound package response to unblock the
+		// caller's send request.
+		currentPkg.deliverOutboundPkgResp()
+
 		err := p.waitForTransferTxConf(&currentPkg)
 		return &currentPkg, err
 

tapfreighter/parcel.go

@@ -789,9 +789,9 @@ func outputAnchor(anchorTx *tapsend.AnchorTransaction, vOut *tappsbt.VOutput,
 	}, nil
 }
 
-// deliverTxBroadcastResp delivers a response for the parcel back to the
+// deliverOutboundPkgResp delivers a response for the parcel back to the
 // receiver over the response channel.
-func (s *sendPackage) deliverTxBroadcastResp() {
+func (s *sendPackage) deliverOutboundPkgResp() {
 	// Ensure that we have a response channel to deliver the response over.
 	// We may not have one if the package send process was recommenced after
 	// a restart.