wallet: register scriptpubkey watches at startup

diff --git a/lightningd/lightningd.c b/lightningd/lightningd.c
index 682900c..44ed3fa 100644
--- a/lightningd/lightningd.c
+++ b/lightningd/lightningd.c
@@ -1367,17 +1367,29 @@ int main(int argc, char *argv[])
 	trace_span_end(ld->topology);
 
 	/*~ Stand up the watchman: it queues bwatch RPC requests until the
-	 * bwatch plugin reports ready, then replays them.  Must come after
-	 * setup_topology so start_block reflects the last-processed height.
+	 * bwatch plugin reports ready, then replays them.  Must come before
+	 * init_wallet_scriptpubkey_watches so the watches have somewhere to
+	 * enqueue, and after setup_topology so start_block reflects the
+	 * last-processed height.
 	 *
 	 * bwatch is opt-in for now: the --experimental-bwatch flag is
 	 * registered by the bwatch plugin, so peek at the configvar to gate
 	 * the lightningd side too.  Without it, ld->watchman stays NULL and
 	 * the watchman_* entry points are no-ops, leaving chain_topology as
 	 * the only chain watcher. */
-	if (bwatch_enabled(ld))
+	if (bwatch_enabled(ld)) {
 		ld->watchman = watchman_new(ld, ld);
 
+		/*~ Reads intvars and the addresses table, so needs a
+		 * transaction (the datastore writes it triggers self-wrap
+		 * when necessary). */
+		db_begin_transaction(ld->wallet->db);
+		trace_span_start("init_wallet_scriptpubkey_watches", ld->wallet);
+		init_wallet_scriptpubkey_watches(ld->wallet);
+		trace_span_end(ld->wallet);
+		db_commit_transaction(ld->wallet->db);
+	}
+
 	db_begin_transaction(ld->wallet->db);
 	trace_span_start("delete_old_htlcs", ld->wallet);
 	wallet_delete_old_htlcs(ld->wallet);
diff --git a/lightningd/test/run-find_my_abspath.c b/lightningd/test/run-find_my_abspath.c
index fc37822..ffd6cbe 100644
--- a/lightningd/test/run-find_my_abspath.c
+++ b/lightningd/test/run-find_my_abspath.c
@@ -92,6 +92,9 @@ void htlcs_notify_new_block(struct lightningd *ld UNNEEDED)
 void htlcs_resubmit(struct lightningd *ld UNNEEDED,
 		    struct htlc_in_map *unconnected_htlcs_in STEALS UNNEEDED)
 { fprintf(stderr, "htlcs_resubmit called!\n"); abort(); }
+/* Generated stub for init_wallet_scriptpubkey_watches */
+void init_wallet_scriptpubkey_watches(struct wallet *w UNNEEDED)
+{ fprintf(stderr, "init_wallet_scriptpubkey_watches called!\n"); abort(); }
 /* Generated stub for invoices_start_expiration */
 void invoices_start_expiration(struct lightningd *ld UNNEEDED)
 { fprintf(stderr, "invoices_start_expiration called!\n"); abort(); }
diff --git a/wallet/wallet.c b/wallet/wallet.c
index 0b12d37..5d54491 100644
--- a/wallet/wallet.c
+++ b/wallet/wallet.c
@@ -1011,6 +1011,43 @@ bool wallet_can_spend(struct wallet *w, const u8 *script, size_t script_len,
 	return true;
 }
 
+static void watch_newindex_scripts(struct lightningd *ld,
+				   u64 keyidx,
+				   enum addrtype addrtype)
+{
+	struct pubkey pubkey;
+	const u8 *scriptpubkey;
+	bool legacy = (ld->bip86_base == NULL);
+	u32 start_block = UINT32_MAX;
+
+	if (ld->bip86_base)
+		bip86_pubkey(ld, &pubkey, keyidx);
+	else
+		bip32_pubkey(ld, &pubkey, keyidx);
+
+	if (addrtype & ADDR_BECH32) {
+		scriptpubkey = scriptpubkey_p2wpkh(tmpctx, &pubkey);
+		wallet_add_bwatch_scriptpubkey(ld, keyidx, start_block,
+					       scriptpubkey,
+					       tal_bytelen(scriptpubkey));
+
+		/* Pre-24.11 ADDR_ALL can include legacy wrapped form. */
+		if (addrtype == ADDR_ALL && legacy) {
+			const u8 *p2sh = scriptpubkey_p2sh(tmpctx, scriptpubkey);
+			wallet_add_bwatch_scriptpubkey(ld, keyidx, start_block,
+						       p2sh,
+						       tal_bytelen(p2sh));
+		}
+	}
+
+	if (addrtype & ADDR_P2TR) {
+		scriptpubkey = scriptpubkey_p2tr(tmpctx, &pubkey);
+		wallet_add_bwatch_scriptpubkey(ld, keyidx, start_block,
+					       scriptpubkey,
+					       tal_bytelen(scriptpubkey));
+	}
+}
+
 s64 wallet_get_newindex(struct lightningd *ld, enum addrtype addrtype)
 {
 	struct db_stmt *stmt;
@@ -1034,6 +1071,8 @@ s64 wallet_get_newindex(struct lightningd *ld, enum addrtype addrtype)
 	db_bind_int(stmt, wallet_addrtype_in_db(addrtype));
 	db_exec_prepared_v2(take(stmt));
 
+	watch_newindex_scripts(ld, newidx, addrtype);
+
 	return newidx;
 }
 
@@ -8033,6 +8072,33 @@ void wallet_add_bwatch_scriptpubkey(struct lightningd *ld,
 				    script, script_len, start_block);
 }
 
+/* Register perennial bwatch watches for every scriptpubkey wallet_can_spend()
+ * recognizes, including keyscan_gap lookahead.  UINT32_MAX avoids a per-key
+ * startup rescan; existing outputs come from migration and catch-up comes from
+ * bwatch polling. */
+void init_wallet_scriptpubkey_watches(struct wallet *w)
+{
+	struct wallet_address_htable_iter it;
+	u64 bip32_max_index = db_get_intvar(w->db, "bip32_max_index", 0);
+	u64 bip86_max_index = db_get_intvar(w->db, "bip86_max_index", 0);
+	u64 max_index = bip32_max_index > bip86_max_index
+		? bip32_max_index : bip86_max_index;
+	u32 start_block = UINT32_MAX;
+
+	/* Extend the table to cover every key we've derived plus lookahead;
+	 * same rule wallet_can_spend applies. */
+	while (w->our_addresses_maxindex < max_index + w->keyscan_gap)
+		our_addresses_add_for_index(w, ++w->our_addresses_maxindex);
+
+	for (struct wallet_address *waddr
+		     = wallet_address_htable_first(w->our_addresses, &it);
+	     waddr;
+	     waddr = wallet_address_htable_next(w->our_addresses, &it)) {
+		wallet_add_bwatch_scriptpubkey(w->ld, waddr->index, start_block,
+					       waddr->swl.script, waddr->swl.len);
+	}
+}
+
 /* Insert a wallet-owned UTXO row into our_outputs.  If the outpoint was
  * previously inserted unconfirmed (blockheight=0) and we now have a real
  * blockheight, promote the row so coin selection can treat it as
@@ -8223,14 +8289,6 @@ static void bwatch_got_utxo(struct wallet *w,
 	watchman_watch_outpoint(w->ld,
 				owner_wallet_utxo(tmpctx, &output->outpoint),
 				&output->outpoint, start_block);
-
-	/* Unconfirmed: keep watching the scriptpubkey so bwatch tells us when
-	 * the output confirms.  UINT32_MAX = perennial watch: never skip on
-	 * reorg, never rescan. */
-	if (!blockheight)
-		wallet_add_bwatch_scriptpubkey(w->ld, keyindex, UINT32_MAX,
-					       output->txout->script,
-					       output->txout->script_len);
 }
 
 /* A wallet/spk watch owner suffix is "<keyindex>/<form>", as written by
diff --git a/wallet/wallet.h b/wallet/wallet.h
index 366a558..607fa8d 100644
--- a/wallet/wallet.h
+++ b/wallet/wallet.h
@@ -2098,4 +2098,9 @@ void wallet_add_bwatch_scriptpubkey(struct lightningd *ld,
 				    const u8 *script,
 				    size_t script_len);
 
+/* Register a bwatch watch for every scriptpubkey wallet_can_spend
+ * recognizes: every HD key up through {bip32,bip86}_max_index plus the
+ * keyscan_gap lookahead, in the address forms actually issued. */
+void init_wallet_scriptpubkey_watches(struct wallet *w);
+
 #endif /* LIGHTNING_WALLET_WALLET_H */