From ed28f7350bdad374d92f92b033543f76ca0e61e3 Mon Sep 17 00:00:00 2001
From: Jimmy Song <jaejoon@gmail.com>
Date: Sun, 1 Mar 2026 04:06:49 -0600
Subject: [PATCH] Add regtest address support to address_to_script_pubkey

- Handle bcrt1q (P2WPKH len 44, P2WSH len 64) and bcrt1p (P2TR len 64)
  prefixes in address_to_script_pubkey()
- TxFetcher.get_url() now raises a clear ValueError for regtest instead
  of an unhelpful KeyError
- Add tests for regtest P2WPKH, P2WSH, and P2TR address roundtrips
- Add test for TxFetcher regtest error message

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 buidl/script.py           | 13 +++++++------
 buidl/test/test_script.py | 27 +++++++++++++++++++++++++++
 buidl/test/test_tx.py     |  7 +++++++
 buidl/tx.py               |  5 +++++
 4 files changed, 46 insertions(+), 6 deletions(-)

diff --git a/buidl/script.py b/buidl/script.py
index 0952b1e..006d6e2 100644
--- a/buidl/script.py
+++ b/buidl/script.py
@@ -613,15 +613,16 @@ def address_to_script_pubkey(s):
         # p2sh
         h160 = decode_base58(s)
         return P2SHScriptPubKey(h160)
-    elif s[:4] in ("bc1q", "tb1q"):
-        if len(s) == 42:
+    elif s[:4] in ("bc1q", "tb1q") or s[:6] == "bcrt1q":
+        # regtest p2wpkh is len 44, p2wsh is len 64 (2 extra for "bcrt" vs "bc"/"tb")
+        if len(s) in (42, 44):
             # p2wpkh
             return P2WPKHScriptPubKey(decode_bech32(s)[2])
-        elif len(s) == 62:
-            # p2wskh
+        elif len(s) in (62, 64):
+            # p2wsh
             return P2WSHScriptPubKey(decode_bech32(s)[2])
-    elif s[:4] in ("bc1p", "tb1p"):
-        if len(s) != 62:
+    elif s[:4] in ("bc1p", "tb1p") or s[:6] == "bcrt1p":
+        if len(s) not in (62, 64):
             raise RuntimeError(f"unknown type of address: {s}")
         # p2tr
         return P2TRScriptPubKey(decode_bech32(s)[2])
diff --git a/buidl/test/test_script.py b/buidl/test/test_script.py
index c0c8de4..7a011d7 100644
--- a/buidl/test/test_script.py
+++ b/buidl/test/test_script.py
@@ -8,6 +8,7 @@
     address_to_script_pubkey,
     P2PKHScriptPubKey,
     P2SHScriptPubKey,
+    P2TRScriptPubKey,
     P2WPKHScriptPubKey,
     P2WSHScriptPubKey,
     RedeemScript,
@@ -237,3 +238,29 @@ def test_addr_to_script_pubkey(self):
             res = address_to_script_pubkey(addr)
             self.assertEqual(scriptpubkey_type, type(res))
             self.assertEqual(res.address(network=network), addr)
+
+    def test_address_to_script_pubkey_regtest(self):
+        tests = (
+            # regtest P2WPKH (bcrt1q..., length 44)
+            (
+                P2WPKHScriptPubKey,
+                "bcrt1qw508d6qejxtdg4y5r3zarvary0c5xw7kygt080",
+                "regtest",
+            ),
+            # regtest P2WSH (bcrt1q..., length 64)
+            (
+                P2WSHScriptPubKey,
+                "bcrt1qrp33g0q5c5txsp9arysrx4k6zdkfs4nce4xj0gdcccefvpysxf3qzf4jry",
+                "regtest",
+            ),
+            # regtest P2TR (bcrt1p..., length 64)
+            (
+                P2TRScriptPubKey,
+                "bcrt1prp33g0q5c5txsp9arysrx4k6zdkfs4nce4xj0gdcccefvpysxf3qg74mmc",
+                "regtest",
+            ),
+        )
+        for scriptpubkey_type, addr, network in tests:
+            res = address_to_script_pubkey(addr)
+            self.assertEqual(scriptpubkey_type, type(res))
+            self.assertEqual(res.address(network=network), addr)
diff --git a/buidl/test/test_tx.py b/buidl/test/test_tx.py
index 769489a..42ed766 100644
--- a/buidl/test/test_tx.py
+++ b/buidl/test/test_tx.py
@@ -428,6 +428,13 @@ def test_coinbase_height(self):
         self.assertIsNone(tx.coinbase_height())
 
 
+class TxFetcherRegtestTest(OfflineTestCase):
+    def test_get_url_regtest(self):
+        with self.assertRaises(ValueError) as cm:
+            TxFetcher.get_url("regtest")
+        self.assertIn("regtest", str(cm.exception))
+
+
 @skipUnless(
     getenv("INCLUDE_NETWORK_TESTS"),
     reason="Requires (unreliable) network connection",
diff --git a/buidl/tx.py b/buidl/tx.py
index 3837759..4ab0be4 100644
--- a/buidl/tx.py
+++ b/buidl/tx.py
@@ -51,6 +51,11 @@ class TxFetcher:
 
     @classmethod
     def get_url(cls, network="mainnet"):
+        if network not in URL:
+            raise ValueError(
+                f"No URL available for network '{network}'. "
+                "TxFetcher only supports mainnet, testnet, and signet."
+            )
         return URL[network]
 
     @classmethod