lightningd: scan outputs for BIP86 addresses

diff --git a/common/daemon.c b/common/daemon.c
index c3adac2..6515828 100644
--- a/common/daemon.c
+++ b/common/daemon.c
@@ -1,5 +1,8 @@
 #include "config.h"
 #include <assert.h>
+/*~ This is Ian Lance Taylor's libbacktrace.  It turns out that it's
+ * horrifically difficult to obtain a decent backtrace in C; the standard
+ * backtrace function is useless in most programs. */
 #include <backtrace-supported.h>
 #include <backtrace.h>
 #include <ccan/err/err.h>
diff --git a/lightningd/lightningd.c b/lightningd/lightningd.c
index f512822..fda955d 100644
--- a/lightningd/lightningd.c
+++ b/lightningd/lightningd.c
@@ -21,9 +21,8 @@
  * before anything else. */
 #include "config.h"
 
-/*~ This is Ian Lance Taylor's libbacktrace.  It turns out that it's
- * horrifically difficult to obtain a decent backtrace in C; the standard
- * backtrace function is useless in most programs. */
+/*~ Various bitcoin-related helpers live in the bitcoin/ directory */
+#include <bitcoin/script.h>
 
 /*~ These headers are from CCAN: http://ccodearchive.net.
  *
@@ -56,8 +55,8 @@
 #include <common/timeout.h>
 #include <common/trace.h>
 #include <common/version.h>
-#include <db/exec.h>
 
+#include <db/exec.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <header_versions_gen.h>
@@ -676,7 +675,7 @@ static void init_txfilter(struct wallet *w,
 	struct ext_key ext;
 	/*~ Note the use of ccan/short_types u64 rather than uint64_t.
 	 * Thank me later. */
-	u64 bip32_max_index;
+	u64 bip32_max_index, bip86_max_index;
 
 	bip32_max_index = db_get_intvar(w->db, "bip32_max_index", 0);
 	/*~ One of the C99 things I unequivocally approve: for-loop scope. */
@@ -686,6 +685,17 @@ static void init_txfilter(struct wallet *w,
 		}
 		txfilter_add_derkey(filter, ext.pub_key);
 	}
+
+	/* If BIP86 is enabled, also add BIP86-derived keys to the filter */
+	if (w->ld->bip86_base) {
+		bip86_max_index = db_get_intvar(w->db, "bip86_max_index", 0);
+		for (u64 i = 0; i <= bip86_max_index + w->keyscan_gap; i++) {
+			struct pubkey pubkey;
+			bip86_pubkey(w->ld, &pubkey, i);
+			u8 *script = scriptpubkey_p2tr(tmpctx, &pubkey);
+			txfilter_add_scriptpubkey(filter, take(script));
+		}
+	}
 }
 
 /*~ The normal advice for daemons is to move into the root directory, so you
diff --git a/lightningd/test/run-find_my_abspath.c b/lightningd/test/run-find_my_abspath.c
index 7f15dc1..9953225 100644
--- a/lightningd/test/run-find_my_abspath.c
+++ b/lightningd/test/run-find_my_abspath.c
@@ -227,6 +227,12 @@ struct wallet *wallet_new(struct lightningd *ld UNNEEDED, struct timers *timers
 /* Generated stub for wallet_sanity_check */
 bool wallet_sanity_check(struct wallet *w UNNEEDED)
 { fprintf(stderr, "wallet_sanity_check called!\n"); abort(); }
+/* Generated stub for bip86_pubkey */
+void bip86_pubkey(struct lightningd *ld UNNEEDED, struct pubkey *pubkey UNNEEDED, u32 index UNNEEDED)
+{ fprintf(stderr, "bip86_pubkey called!\n"); abort(); }
+/* Generated stub for txfilter_add_scriptpubkey */
+void txfilter_add_scriptpubkey(struct txfilter *filter UNNEEDED, const u8 *script TAKES UNNEEDED)
+{ fprintf(stderr, "txfilter_add_scriptpubkey called!\n"); abort(); }
 /* AUTOGENERATED MOCKS END */
 
 struct logger *crashlog;
diff --git a/wallet/wallet.c b/wallet/wallet.c
index e761929..0e0d5a0 100644
--- a/wallet/wallet.c
+++ b/wallet/wallet.c
@@ -148,6 +148,12 @@ static void our_addresses_add_for_index(struct wallet *w, u32 i)
 	/* FIXME: We could deprecate P2SH once we don't see
 	 * any, since we stopped publishing them in 24.02 */
 	if (!wallet_get_addrtype(w, i, &addrtype)) {
+		if (w->ld->bip86_base) {
+			/* Derive and add BIP86 script for this index */
+			our_addresses_add_bip86_for_index(w, i);
+			return;
+		}
+
 		const u8 *addr;
 		scriptpubkey = scriptpubkey_p2wpkh_derkey(NULL, ext.pub_key);
 		addr = scriptpubkey_p2sh(NULL, scriptpubkey);
@@ -205,7 +211,17 @@ static void our_addresses_init(struct wallet *w)
 	w->our_addresses_maxindex = 0;
 	w->our_addresses = new_htable(w, wallet_address_htable);
 
-	our_addresses_add_for_index(w, w->our_addresses_maxindex);
+	/* If BIP86 is enabled, prefill the address table up to keyscan_gap so
+	 * rescans immediately include BIP86 scripts without needing prior
+	 * address allocations. */
+	if (w->ld->bip86_base) {
+		for (u32 i = 0; i <= w->keyscan_gap; i++) {
+			our_addresses_add_for_index(w, i);
+		}
+		w->our_addresses_maxindex = w->keyscan_gap;
+	} else {
+		our_addresses_add_for_index(w, w->our_addresses_maxindex);
+	}
 }
 
 static void outpointfilters_init(struct wallet *w)