build: automatic block height update

diff --git a/shared/block_height.py b/shared/block_height.py
new file mode 100644
index 0000000..cc57e64
--- /dev/null
+++ b/shared/block_height.py
@@ -0,0 +1,9 @@
+# (c) Copyright 2026 by Coinkite Inc. This file is covered by license found in COPYING-CC.
+#
+# AUTO-generated.
+#
+# Updated: 2026-06-19 14:13:23 UTC
+
+BLOCK_HEIGHT = 932301
+
+# EOF
diff --git a/shared/chains.py b/shared/chains.py
index 67b4060..1531b74 100644
--- a/shared/chains.py
+++ b/shared/chains.py
@@ -8,6 +8,7 @@ from ubinascii import hexlify as b2a_hex
 from public_constants import AF_CLASSIC, AF_P2WPKH, AF_P2TR
 from public_constants import AF_P2SH, AF_P2WSH, AF_P2WPKH_P2SH, AF_P2WSH_P2SH
 from public_constants import AFC_PUBKEY, AFC_SEGWIT, AFC_BECH32, AFC_SCRIPT
+from block_height import BLOCK_HEIGHT
 from serializations import hash160, ser_compact_size, disassemble
 from ucollections import namedtuple
 from opcodes import OP_RETURN, OP_1, OP_16
@@ -297,7 +298,7 @@ class BitcoinMain(ChainsBase):
     # see <https://github.com/bitcoin/bitcoin/blob/master/src/chainparams.cpp#L140>
     ctype = 'BTC'
     name = 'Bitcoin Mainnet'
-    ccc_min_block = 939464          # Mar 5/2026
+    ccc_min_block = BLOCK_HEIGHT
 
     slip132 = {
         AF_CLASSIC:     Slip132Version(0x0488B21E, 0x0488ADE4, 'x'),
diff --git a/shared/manifest.py b/shared/manifest.py
index a2cc842..d8fa284 100644
--- a/shared/manifest.py
+++ b/shared/manifest.py
@@ -6,6 +6,7 @@ freeze_as_mpy('', [
 	'address_explorer.py',
 	'auth.py',
 	'backups.py',
+	'block_height.py',
 	'callgate.py',
 	'ccc.py',
 	'chains.py',
diff --git a/stm32/make_block_height.py b/stm32/make_block_height.py
new file mode 100644
index 0000000..6dd75ca
--- /dev/null
+++ b/stm32/make_block_height.py
@@ -0,0 +1,81 @@
+#!/usr/bin/env python3
+#
+# (c) Copyright 2026 by Coinkite Inc. This file is covered by license found in COPYING-CC.
+#
+# Capture current (mainnet) block height for SSSP/CCC features
+#
+import sys, time, datetime
+import urllib.request
+
+
+FILE_NAME = "../shared/block_height.py"
+
+
+def _get_block_height(url):
+    with urllib.request.urlopen(url) as response:
+        height_data = response.read().decode().strip()
+        return int(height_data)
+
+
+def get_block_height(url):
+    try:
+        return _get_block_height(url)
+    except:
+        time.sleep(2)
+        return _get_block_height(url)
+
+
+def parse_block_height_file():
+    with open(FILE_NAME, "r") as f:
+        for l in f.readlines():
+            if l.startswith("BLOCK_HEIGHT ="):
+                return int(l.split("=")[-1].strip())
+
+    return None
+
+
+def write_block_height_file(block_height):
+    now = datetime.datetime.now(datetime.timezone.utc)
+    with open(FILE_NAME, "wt") as f:
+        f.write('''\
+# (c) Copyright 2026 by Coinkite Inc. This file is covered by license found in COPYING-CC.
+#
+# AUTO-generated.
+#
+
+# As of %s UTC
+BLOCK_HEIGHT = %d
+
+# EOF
+''' % (now.strftime("%Y-%m-%d %H:%M:%S"), block_height))
+
+
+def main():
+    current_height = None
+    for _ in range(2):
+        bh_a = get_block_height("https://mempool.space/api/blocks/tip/height")
+        bh_b = get_block_height("https://blockstream.info/api/blocks/tip/height")
+        if bh_a == bh_b:
+            current_height = bh_a
+            break
+
+        time.sleep(5)
+
+    if current_height is None:
+        raise RuntimeError("Could not get current block height")
+
+    file_block_height = parse_block_height_file()
+    if file_block_height is None:
+        raise RuntimeError("Could not parse block height from file")
+
+    if current_height > file_block_height:
+        write_block_height_file(current_height)
+        sys.exit(1)
+    else:
+        sys.exit(0)
+
+
+if __name__ == "__main__":
+    main()
+
+# EOF
diff --git a/stm32/make_filetime.py b/stm32/make_filetime.py
index f795dc8..6ab9dfe 100755
--- a/stm32/make_filetime.py
+++ b/stm32/make_filetime.py
@@ -5,14 +5,14 @@
 # Capture build time and version number into a number used as the timestamp on
 # all created files for that Coldcard version.
 #
-import os, sys, time, datetime
+import os, sys, datetime
 
 out_fname, version = sys.argv[1:]
 
 assert out_fname.endswith('.c'), out_fname
 
 if os.path.exists(out_fname):
-    # to help deterministic builds, don't replace the file from git if verison # is right
+    # to help deterministic builds, don't replace the file from git if version # is right
     with open(out_fname, 'rt') as fd:
         if ('// version: %s\n' % version) in fd.read():
             print("==> %s already version %s; not changing it" % (out_fname, version))
@@ -22,7 +22,7 @@ if os.path.exists(out_fname):
 today = datetime.date.today()
 value = ((today.year - 1980) << 25) | (today.month << 21) | (today.day << 16) 
 
-# only 2second resolution for times, so can only support minor verion up to x.x.5 and hard to see
+# only 2second resolution for times, so can only support minor version up to x.x.5 and hard to see
 # anyway, let's omit ... worst case, use the date instead
 ver = ''.join(v for v in version if v in '0123456789.')     # strip letter codes from end
 h, m, _ = [int(x) for x in ver.split('b')[0].split('.')]
diff --git a/stm32/shared.mk b/stm32/shared.mk
index 6bf29a3..e0e03d2 100644
--- a/stm32/shared.mk
+++ b/stm32/shared.mk
@@ -82,6 +82,18 @@ $(BOARD)/file_time.c: make_filetime.py *-Makefile shared.mk
 	./make_filetime.py $(BOARD)/file_time.c $(VERSION_STRING)
 	cp $(BOARD)/file_time.c .
 
+
+.PHONY: block_height
+
+block_height:
+	@python3 make_block_height.py; \
+	if [ $$? -eq 0 ]; then \
+		echo "Block Height file already up-to-date."; \
+	else \
+		echo "Block Height file updated."; \
+		git commit -m "update block height" ../shared/block_height.py; \
+	fi
+
 # Make a factory release: using key #1
 # - when executed in a repro w/o the required key, it defaults to key zero
 # - and that's what happens inside the Docker build
@@ -91,7 +103,7 @@ production.bin: firmware-signed.bin Makefile
 SUBMAKE = $(MAKE) -f $(PARENT_MKFILE)
 
 .PHONY: release
-release: submods-match code-committed
+release: submods-match code-committed block_height
 	$(SUBMAKE) clean
 	$(SUBMAKE) repro
 	test -f built/production.bin
@@ -118,7 +130,7 @@ rc1:
 rc2: RC2_TIMESTAMP = $(shell date "+%F_%H%M")
 rc2: RC2_FNAME = ./RC2-$(RC2_TIMESTAMP)-$(HW_MODEL)-coldcard.dfu
 rc2: RC2_FNAME_FACT = ./RC2-$(RC2_TIMESTAMP)-$(HW_MODEL)-factory.dfu
-rc2: submods-match code-committed
+rc2: submods-match code-committed block_height
 	$(SUBMAKE) clean
 	$(SUBMAKE) repro
 	test -f built/production.bin