also return preimage on listinvoices.

lightningd/invoice.c

@@ -61,6 +61,7 @@ static void json_add_invoice(struct json_stream *response,
 					    "msatoshi_received",
 					    "amount_received_msat");
 		json_add_u64(response, "paid_at", inv->paid_timestamp);
+		json_add_preimage(response, "payment_preimage", &inv->r);
 	}
 	if (inv->description)
 		json_add_string(response, "description", inv->description);
@@ -572,7 +573,6 @@ static void gossipd_incoming_channels_reply(struct subd *gossipd,
 	json_add_sha256(response, "payment_hash", &details->rhash);
 	json_add_u64(response, "expires_at", details->expiry_time);
 	json_add_string(response, "bolt11", details->bolt11);
-	json_add_preimage(response, "preimage", &details->r);
 
 	/* Warn if there's not sufficient incoming capacity. */
 	if (tal_count(info->b11->routes) == 0) {

tests/test_pay.py

@@ -517,6 +517,7 @@ def test_sendpay(node_factory):
     assert only_one(l2.rpc.listinvoices('testpayment2')['invoices'])['status'] == 'paid'
     assert only_one(l2.rpc.listinvoices('testpayment2')['invoices'])['pay_index'] == 1
     assert only_one(l2.rpc.listinvoices('testpayment2')['invoices'])['msatoshi_received'] == rs['msatoshi']
+    assert only_one(l2.rpc.listinvoices('testpayment2')['invoices'])['payment_preimage'] == preimage
 
     # Balances should reflect it.
     def check_balances():