From 4b1f2a079e4d14fcff472c65547ce9afc047487b Mon Sep 17 00:00:00 2001
From: Sangbida Chaudhuri <101164840+sangbida@users.noreply.github.com>
Date: Tue, 13 Jan 2026 22:52:12 +1030
Subject: [PATCH] lightningd: use BIP86 derivation for P2TR in HTLC rebroadcast
 change outputs

---
 lightningd/onchain_control.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/lightningd/onchain_control.c b/lightningd/onchain_control.c
index 1e04cebd5..8d7f99f4e 100644
--- a/lightningd/onchain_control.c
+++ b/lightningd/onchain_control.c
@@ -1154,7 +1154,12 @@ static bool consider_onchain_htlc_tx_rebroadcast(struct channel *channel,
 	if (!amount_sat_eq(change, AMOUNT_SAT(0))) {
 		/* Append change output. */
 		struct pubkey final_key;
-		bip32_pubkey(ld, &final_key, channel->final_key_idx);
+		/* Use BIP86 derivation for P2TR if available, otherwise BIP32 */
+		if (ld->bip86_base) {
+			bip86_pubkey(ld, &final_key, channel->final_key_idx);
+		} else {
+			bip32_pubkey(ld, &final_key, channel->final_key_idx);
+		}
 		psbt_append_output(psbt,
 				   scriptpubkey_p2tr(tmpctx, &final_key),
 				   change);