diff -Nru kylin-ai-vector-engine-1.2.0.1/debian/changelog kylin-ai-vector-engine-1.2.0.1/debian/changelog
--- kylin-ai-vector-engine-1.2.0.1/debian/changelog	2026-05-07 13:38:34.000000000 +0200
+++ kylin-ai-vector-engine-1.2.0.1/debian/changelog	2026-10-20 16:31:16.000000000 +0200
@@ -1,3 +1,10 @@
+kylin-ai-vector-engine (1.2.0.1-1.1) unstable; urgency=medium
+
+  * Non-maintainer upload.
+  * Fix FTBFS with fmt 11 in the embedded folly copy. (Closes: #1150444)
+
+ -- Anton Gladky <gladk@debian.org>  Tue, 20 Oct 2026 16:31:16 +0200
+
 kylin-ai-vector-engine (1.2.0.1-1) unstable; urgency=medium
 
   * Initial release
diff -Nru kylin-ai-vector-engine-1.2.0.1/debian/patches/0001-folly-fix-build-with-fmt-11.patch kylin-ai-vector-engine-1.2.0.1/debian/patches/0001-folly-fix-build-with-fmt-11.patch
--- kylin-ai-vector-engine-1.2.0.1/debian/patches/0001-folly-fix-build-with-fmt-11.patch	1970-01-01 01:00:00.000000000 +0100
+++ kylin-ai-vector-engine-1.2.0.1/debian/patches/0001-folly-fix-build-with-fmt-11.patch	2026-10-20 16:31:16.000000000 +0200
@@ -0,0 +1,31 @@
+From: Anton Gladky <gladk@debian.org>
+Date: Tue, 20 Oct 2026 12:00:00 +0200
+Subject: folly: fix FTBFS with fmt 11
+
+With fmt 11, formatting a folly::StringPiece through FMT_COMPILE is
+ambiguous, because folly::Range is detected both as a string-like type
+and as a type with a custom formatter:
+
+  error: call of overloaded 'write<char>(..., const folly::Range<const char*>&)'
+  is ambiguous
+
+Pass a std::string instead, which fmt formats unambiguously.
+
+Bug-Debian: https://bugs.debian.org/1150444
+Forwarded: not-needed
+Last-Update: 2026-10-20
+---
+ thirdparty/folly/folly/Singleton.cpp | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/thirdparty/folly/folly/Singleton.cpp
++++ b/thirdparty/folly/folly/Singleton.cpp
+@@ -168,7 +168,7 @@ void singletonPrintDestructionStackTrace
+   auto const msg = fmt::format(
+       FOLLY_FMT_COMPILE(
+           "nullptr_t should be passed if you want {} to be default constructed"),
+-      folly::StringPiece(demangle(type)));
++      demangle(type).toStdString());
+   throw std::logic_error(msg);
+ }
+
diff -Nru kylin-ai-vector-engine-1.2.0.1/debian/patches/series kylin-ai-vector-engine-1.2.0.1/debian/patches/series
--- kylin-ai-vector-engine-1.2.0.1/debian/patches/series	1970-01-01 01:00:00.000000000 +0100
+++ kylin-ai-vector-engine-1.2.0.1/debian/patches/series	2026-10-20 16:31:16.000000000 +0200
@@ -0,0 +1 @@
+0001-folly-fix-build-with-fmt-11.patch