diff --git a/CMakeLists.txt b/CMakeLists.txt
index b1dda88c..a55c8e22 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -75,9 +75,10 @@ set(DOX_EXCLUDE_PATTERNS [=[
 # in reverse topological order i.e. dependencies first
 
 add_subdirectory(xo-cmake)
-add_subdirectory(xo-reflectutil)  # header-only reflect support
-add_subdirectory(xo-facet)   # sep iface,data
 add_subdirectory(xo-indentlog)
+add_subdirectory(xo-reflectutil)  # header-only reflect support
+add_subdirectory(xo-arena)   # arena allocator (DArena)
+add_subdirectory(xo-facet)   # sep iface,data
 add_subdirectory(xo-allocutil)
 add_subdirectory(xo-refcnt)
 add_subdirectory(xo-subsys)
diff --git a/xo-alloc2/cmake/xo_alloc2Config.cmake.in b/xo-alloc2/cmake/xo_alloc2Config.cmake.in
index 65ab5b1c..e0b5e0b0 100644
--- a/xo-alloc2/cmake/xo_alloc2Config.cmake.in
+++ b/xo-alloc2/cmake/xo_alloc2Config.cmake.in
@@ -2,6 +2,7 @@
 
 include(CMakeFindDependencyMacro)
 #find_dependency(indentlog)
+find_depnedency(xo_arena)
 find_dependency(xo_facet)
 include("${CMAKE_CURRENT_LIST_DIR}/@PROJECT_NAME@Targets.cmake")
 check_required_components("@PROJECT_NAME@")
diff --git a/xo-alloc2/include/xo/alloc2/ArenaConfig.hpp b/xo-alloc2/include/xo/alloc2/ArenaConfig.hpp
deleted file mode 100644
index 7d3f3478..00000000
--- a/xo-alloc2/include/xo/alloc2/ArenaConfig.hpp
+++ /dev/null
@@ -1,70 +0,0 @@
-/** @file ArenaConfig.hpp
- *
- *  @author Roland Conybeare, Dec 2025
- **/
-
-#pragma once
-
-#include <string>
-#include <cstdint>
-
-namespace xo {
-    namespace mm {
-
-        /** @class ArenaConfig
-         *  @brief configuration for a @ref DArena instance
-         **/
-        struct ArenaConfig {
-            /** @defgroup mm-arenaconfig-ctors ArenaConfig ctors **/
-            ///@{
-
-            /** create anonymous arena with size @p z **/
-            static ArenaConfig simple(std::size_t z);
-
-            ///@}
-
-            /** @defgroup mm-arenaconfig-instance-vars ArenaConfig members **/
-            ///@{
-
-            /** optional name, for diagnostics **/
-            std::string name_;
-            /** desired arena size -- hard max = reserved virtual memory **/
-            std::size_t size_;
-            /** hugepage size -- using huge pages relieves some TLB pressure
-             *  (provided you use their full extent :)
-             **/
-            std::size_t hugepage_z_ = 2 * 1024 * 1024;
-            /** if non-zero, allocate extra space between allocs, and fill
-             *  with fixed test-pattern contents. Allows for simple
-             *  runtime arena sanitizing checks.
-             *  Will be rounded up to multiple of @ref padding::c_alloc_alignment
-             **/
-            std::size_t guard_z_ = 0;
-            /** if guard_z_ > 0, write at least that many copies
-             *  of this guard byte following each complete allocation
-             **/
-            std::uint8_t guard_byte_ = 0xfd;
-            /** if store_header_flag_ is true: mask bits for allocation size.
-             *  remaining bits can be stolen for other purposes
-             *  otherwise ignored
-             **/
-            /** true to store header (8 bytes) at the beginning of each allocation.
-             *  necessary and sufficient to allows iterating over allocs
-             *  present in arena
-             **/
-            bool store_header_flag_ = false;
-            /** mask applied to 8-byte alloc header.
-             *  bits set to 1 store alloc size; remaining
-             *  bits in alloc header can be used for other purposes.
-             **/
-            std::uint64_t header_size_mask_ = 0xffffffff;
-            /** true to enable debug logging **/
-            bool debug_flag_ = false;
-
-            ///@}
-        };
-
-    } /*namespace mm*/
-} /*namespace xo*/
-
-/* end ArenaConfig.hpp */
diff --git a/xo-alloc2/include/xo/alloc2/alloc/AAllocIterator.hpp b/xo-alloc2/include/xo/alloc2/alloc/AAllocIterator.hpp
index 4b9f4ab9..e7581dc4 100644
--- a/xo-alloc2/include/xo/alloc2/alloc/AAllocIterator.hpp
+++ b/xo-alloc2/include/xo/alloc2/alloc/AAllocIterator.hpp
@@ -23,7 +23,7 @@ namespace xo {
          **/
         struct AAllocIterator {
             using obj_AAllocIterator = xo::facet::obj<AAllocIterator>;
-            using typeseq = xo::facet::typeseq;
+            using typeseq = xo::reflect::typeseq;
 
             /** @defgroup mm-allociterator-methods AllocIterator methods **/
             ///@{
diff --git a/xo-alloc2/include/xo/alloc2/alloc/AAllocator.hpp b/xo-alloc2/include/xo/alloc2/alloc/AAllocator.hpp
index 0fce475c..588b439b 100644
--- a/xo-alloc2/include/xo/alloc2/alloc/AAllocator.hpp
+++ b/xo-alloc2/include/xo/alloc2/alloc/AAllocator.hpp
@@ -5,7 +5,7 @@
 
 #pragma once
 
-#include "AllocError.hpp"
+#include <xo/arena/AllocError.hpp>
 #include "AllocInfo.hpp"
 //#include "AllocIterator.hpp"
 #include "AllocRange.hpp"
diff --git a/xo-alloc2/include/xo/alloc2/alloc/IAllocIterator_Any.hpp b/xo-alloc2/include/xo/alloc2/alloc/IAllocIterator_Any.hpp
index f946c397..1bed0ff1 100644
--- a/xo-alloc2/include/xo/alloc2/alloc/IAllocIterator_Any.hpp
+++ b/xo-alloc2/include/xo/alloc2/alloc/IAllocIterator_Any.hpp
@@ -20,7 +20,7 @@ namespace xo {
          *  @brief AllocIterator implementation for empty variant instance
          **/
         struct IAllocIterator_Any : public AAllocIterator {
-            using typeseq = xo::facet::typeseq;
+            using typeseq = xo::reflect::typeseq;
 
             const AAllocIterator * iface() const { return std::launder(this); }
 
diff --git a/xo-alloc2/include/xo/alloc2/alloc/IAllocIterator_Xfer.hpp b/xo-alloc2/include/xo/alloc2/alloc/IAllocIterator_Xfer.hpp
index e61e326c..251f4afd 100644
--- a/xo-alloc2/include/xo/alloc2/alloc/IAllocIterator_Xfer.hpp
+++ b/xo-alloc2/include/xo/alloc2/alloc/IAllocIterator_Xfer.hpp
@@ -18,7 +18,7 @@ namespace xo {
                   typename IAllocIterator_DRepr>
         struct IAllocIterator_Xfer : public AAllocIterator {
             using Impl = IAllocIterator_DRepr;
-            using typeseq = xo::facet::typeseq;
+            using typeseq = xo::reflect::typeseq;
 
             static const DRepr & _dcast(Copaque d) { return *(const DRepr *)d; }
             static DRepr & _dcast(Opaque d) { return *(DRepr *)d; }
@@ -48,9 +48,9 @@ namespace xo {
         };
 
         template <typename DRepr, typename IAllocIterator_DRepr>
-        xo::facet::typeseq
+        xo::reflect::typeseq
         IAllocIterator_Xfer<DRepr, IAllocIterator_DRepr>::s_typeseq
-        = facet::typeseq::id<DRepr>();
+        = reflect::typeseq::id<DRepr>();
 
         template <typename DRepr, typename IAllocIterator_DRepr>
         bool
diff --git a/xo-alloc2/include/xo/alloc2/alloc/RAllocIterator.hpp b/xo-alloc2/include/xo/alloc2/alloc/RAllocIterator.hpp
index 4e1a95f8..47d59f29 100644
--- a/xo-alloc2/include/xo/alloc2/alloc/RAllocIterator.hpp
+++ b/xo-alloc2/include/xo/alloc2/alloc/RAllocIterator.hpp
@@ -17,7 +17,7 @@ namespace xo {
         public:
             using ObjectType = Object;
             using DataPtr = Object::DataPtr;
-            using typeseq = xo::facet::typeseq;
+            using typeseq = xo::reflect::typeseq;
 
             RAllocIterator() {}
             RAllocIterator(Object::DataPtr data) : Object{std::move(data)} {}
diff --git a/xo-alloc2/include/xo/alloc2/arena/IAllocIterator_DArenaIterator.hpp b/xo-alloc2/include/xo/alloc2/arena/IAllocIterator_DArenaIterator.hpp
index dfe84005..5af231ac 100644
--- a/xo-alloc2/include/xo/alloc2/arena/IAllocIterator_DArenaIterator.hpp
+++ b/xo-alloc2/include/xo/alloc2/arena/IAllocIterator_DArenaIterator.hpp
@@ -6,7 +6,7 @@
 #pragma once
 
 #include "alloc/IAllocIterator_Xfer.hpp"
-#include "arena/DArenaIterator.hpp"
+#include <xo/arena/DArenaIterator.hpp>
 
 namespace xo {
     namespace mm { struct IAllocIterator_DArenaIterator; }
diff --git a/xo-alloc2/include/xo/alloc2/arena/IAllocator_DArena.hpp b/xo-alloc2/include/xo/alloc2/arena/IAllocator_DArena.hpp
index 9f18adc1..4a871822 100644
--- a/xo-alloc2/include/xo/alloc2/arena/IAllocator_DArena.hpp
+++ b/xo-alloc2/include/xo/alloc2/arena/IAllocator_DArena.hpp
@@ -5,7 +5,7 @@
 
 #include "alloc/AAllocator.hpp"
 #include "alloc/IAllocator_Xfer.hpp"
-#include "arena/DArena.hpp"
+#include <xo/arena/DArena.hpp>
 
 namespace xo {
     namespace mm { struct IAllocator_DArena; }
diff --git a/xo-alloc2/src/alloc2/ArenaConfig.cpp b/xo-alloc2/src/alloc2/ArenaConfig.cpp
deleted file mode 100644
index 7f4e4248..00000000
--- a/xo-alloc2/src/alloc2/ArenaConfig.cpp
+++ /dev/null
@@ -1,17 +0,0 @@
-/** @file ArenaConfig.cpp
- *
- *  @author Roland Conybeare, Dec 2025
- **/
-
-#include "ArenaConfig.hpp"
-namespace xo {
-    namespace mm {
-        ArenaConfig
-        ArenaConfig::simple(std::size_t z)
-        {
-            return ArenaConfig { .name_ = "anonymous", .size_ = z };
-        }
-    }
-}
-
-/* end ArenaConfig.cpp */
diff --git a/xo-alloc2/src/alloc2/CMakeLists.txt b/xo-alloc2/src/alloc2/CMakeLists.txt
index 1d66ead5..3a279746 100644
--- a/xo-alloc2/src/alloc2/CMakeLists.txt
+++ b/xo-alloc2/src/alloc2/CMakeLists.txt
@@ -3,23 +3,24 @@
 set(SELF_LIB xo_alloc2)
 set(SELF_SRCS
 
-    AllocError.cpp
-    AllocInfo.cpp
-    cmpresult.cpp
+#    AllocError.cpp
+#    AllocInfo.cpp
+#    cmpresult.cpp
 
     AAllocator.cpp
-    ArenaConfig.cpp
-    DArena.cpp
+#    ArenaConfig.cpp
+#    DArena.cpp
     IAllocator_Any.cpp
     IAllocator_DArena.cpp
 
     IAllocIterator_Any.cpp
-    DArenaIterator.cpp
+#    DArenaIterator.cpp
     IAllocIterator_DArenaIterator.cpp
 
     )
 
 xo_add_shared_library4(${SELF_LIB} ${PROJECT_NAME}Targets ${PROJECT_VERSION} 1 ${SELF_SRCS})
 # note: deps here must also appear in cmake/xo_alloc2Config.cmake.in
+xo_dependency(${SELF_LIB} xo_arena)
 xo_dependency(${SELF_LIB} xo_facet)
 xo_dependency(${SELF_LIB} indentlog)
diff --git a/xo-alloc2/src/alloc2/IAllocIterator_Any.cpp b/xo-alloc2/src/alloc2/IAllocIterator_Any.cpp
index befaea8c..86c2ba72 100644
--- a/xo-alloc2/src/alloc2/IAllocIterator_Any.cpp
+++ b/xo-alloc2/src/alloc2/IAllocIterator_Any.cpp
@@ -9,8 +9,8 @@
 namespace xo {
     namespace mm {
         using xo::facet::DVariantPlaceholder;
-        using xo::facet::typeseq;
         using xo::facet::valid_facet_implementation;
+        using xo::reflect::typeseq;
 
         void
         IAllocIterator_Any::_fatal() {
diff --git a/xo-alloc2/src/alloc2/IAllocator_DArena.cpp b/xo-alloc2/src/alloc2/IAllocator_DArena.cpp
index ed956240..a3bd9613 100644
--- a/xo-alloc2/src/alloc2/IAllocator_DArena.cpp
+++ b/xo-alloc2/src/alloc2/IAllocator_DArena.cpp
@@ -6,8 +6,8 @@
 #include "AllocIterator.hpp"
 #include "arena/IAllocator_DArena.hpp"
 #include "arena/IAllocIterator_DArenaIterator.hpp" // for alloc_range
-#include "arena/DArenaIterator.hpp"
-#include "padding.hpp"
+#include <xo/arena/DArenaIterator.hpp>
+#include <xo/arena/padding.hpp>
 #include <xo/facet/obj.hpp>
 #include <xo/indentlog/scope.hpp>
 #include <cassert>
diff --git a/xo-alloc2/utest/arena.test.cpp b/xo-alloc2/utest/arena.test.cpp
index 6c3278ba..9bd87202 100644
--- a/xo-alloc2/utest/arena.test.cpp
+++ b/xo-alloc2/utest/arena.test.cpp
@@ -5,11 +5,9 @@
 
 #include "xo/alloc2/Allocator.hpp"
 #include "xo/alloc2/alloc/IAllocator_Xfer.hpp"
-//#include "xo/alloc2/DArena.hpp"
 #include "xo/alloc2/arena/IAllocator_DArena.hpp"
-//#include "xo/alloc2/alloc/RAllocator.hpp"
 #include "xo/alloc2/print.hpp"
-#include "xo/alloc2/padding.hpp"
+#include "xo/arena/padding.hpp"
 #include <xo/facet/obj.hpp>
 #include <xo/indentlog/scope.hpp>
 #include <catch2/catch.hpp>
diff --git a/xo-alloc2/utest/random_allocs.cpp b/xo-alloc2/utest/random_allocs.cpp
index 654c6c9a..1f7f833f 100644
--- a/xo-alloc2/utest/random_allocs.cpp
+++ b/xo-alloc2/utest/random_allocs.cpp
@@ -4,8 +4,8 @@
  **/
 
 #include "random_allocs.hpp"
-#include "arena/DArena.hpp"
-#include "padding.hpp"
+#include <xo/arena/DArena.hpp>
+#include <xo/arena/padding.hpp>
 #include <xo/indentlog/scope.hpp>
 #include <xo/indentlog/print/tag.hpp>
 #include <catch2/catch.hpp>
diff --git a/xo-arena/CMakeLists.txt b/xo-arena/CMakeLists.txt
new file mode 100644
index 00000000..24d544ec
--- /dev/null
+++ b/xo-arena/CMakeLists.txt
@@ -0,0 +1,31 @@
+# xo-arena/CMakeLists.txt
+
+cmake_minimum_required(VERSION 3.10)
+
+project(xo_arena VERSION 1.0)
+enable_language(CXX)
+
+include(GNUInstallDirs)
+include(cmake/xo-bootstrap-macros.cmake)
+
+xo_cxx_toplevel_options3()
+
+# ----------------------------------------------------------------
+# c++ settings
+
+# one-time project-specific c++ flags. usually empty
+set(PROJECT_CXX_FLAGS "")
+add_definitions(${PROJECT_CXX_FLAGS})
+
+# ----------------------------------------------------------------
+# output targets
+
+add_subdirectory(src/arena)
+#add_subdirectory(utest)
+
+# ----------------------------------------------------------------
+# cmake export
+
+xo_export_cmake_config(${PROJECT_NAME} ${PROJECT_VERSION} ${PROJECT_NAME}Targets)
+
+# end CMakeLists.txt
diff --git a/xo-arena/README.md b/xo-arena/README.md
deleted file mode 100644
index 6c14c75c..00000000
--- a/xo-arena/README.md
+++ /dev/null
@@ -1 +0,0 @@
-# xo-arena
diff --git a/xo-arena/cmake/xo-bootstrap-macros.cmake b/xo-arena/cmake/xo-bootstrap-macros.cmake
new file mode 100644
index 00000000..2cf387e5
--- /dev/null
+++ b/xo-arena/cmake/xo-bootstrap-macros.cmake
@@ -0,0 +1,33 @@
+# ----------------------------------------------------------------
+# for example:
+#   $ PREFIX=/usr/local   # for example
+#   $ cmake -DCMAKE_MODULE_PATH=prefix -DCMAKE_INSTALL_PREFIX=$PREFIX -B .build
+#
+# will get
+#   CMAKE_MODULE_PATH
+# from xo-cmake-config --cmake-module-path
+#
+# and expect .cmake macros in
+#   CMAKE_MODULE_PATH/xo_macros/xo_cxx.cmake
+# ----------------------------------------------------------------
+
+find_program(XO_CMAKE_CONFIG_EXECUTABLE NAMES xo-cmake-config REQUIRED)
+
+if (("${CMAKE_MODULE_PATH}" STREQUAL "") OR ("${CMAKE_MODULE_PATH}" STREQUAL "prefix"))
+    message(FATAL "could not find xo-cmake-config executable")
+endif()
+
+if (NOT XO_SUBMODULE_BUILD)
+    if (("${CMAKE_MODULE_PATH}" STREQUAL "") OR ("${CMAKE_MODULE_PATH}" STREQUAL prefix))
+        # default to typical install location for xo-project-macros
+        execute_process(COMMAND ${XO_CMAKE_CONFIG_EXECUTABLE} --cmake-module-path OUTPUT_VARIABLE CMAKE_MODULE_PATH)
+        message(STATUS "CMAKE_MODULE_PATH=${CMAKE_MODULE_PATH}")
+    endif()
+endif()
+
+# needs to have been installed somewhere on CMAKE_MODULE_PATH,
+# (e.g. from xo-cmake with the same value for CMAKE_INSTALL_PREFIX)
+#
+include(xo_macros/xo_cxx)
+
+xo_cxx_bootstrap_message()
diff --git a/xo-arena/cmake/xo_arenaConfig.cmake.in b/xo-arena/cmake/xo_arenaConfig.cmake.in
new file mode 100644
index 00000000..1700fb8a
--- /dev/null
+++ b/xo-arena/cmake/xo_arenaConfig.cmake.in
@@ -0,0 +1,13 @@
+@PACKAGE_INIT@
+
+include(CMakeFindDependencyMacro)
+
+# note: changes to find_dependency() calls here
+#       must coordinate with xo_dependency() calls
+#       in CMakeLists.txt
+#
+find_dependency(xo_reflectutil)
+find_dependency(indentlog)
+
+include("${CMAKE_CURRENT_LIST_DIR}/@PROJECT_NAME@Targets.cmake")
+check_required_components("@PROJECT_NAME@")
diff --git a/xo-arena/include/xo/arena/.gitkeep b/xo-arena/include/xo/arena/.gitkeep
new file mode 100644
index 00000000..e69de29b
diff --git a/xo-alloc2/include/xo/alloc2/AllocError.hpp b/xo-arena/include/xo/arena/AllocError.hpp
similarity index 100%
rename from xo-alloc2/include/xo/alloc2/AllocError.hpp
rename to xo-arena/include/xo/arena/AllocError.hpp
diff --git a/xo-alloc2/include/xo/alloc2/AllocHeader.hpp b/xo-arena/include/xo/arena/AllocHeader.hpp
similarity index 100%
rename from xo-alloc2/include/xo/alloc2/AllocHeader.hpp
rename to xo-arena/include/xo/arena/AllocHeader.hpp
diff --git a/xo-alloc2/include/xo/alloc2/AllocHeaderConfig.hpp b/xo-arena/include/xo/arena/AllocHeaderConfig.hpp
similarity index 100%
rename from xo-alloc2/include/xo/alloc2/AllocHeaderConfig.hpp
rename to xo-arena/include/xo/arena/AllocHeaderConfig.hpp
diff --git a/xo-alloc2/include/xo/alloc2/AllocInfo.hpp b/xo-arena/include/xo/arena/AllocInfo.hpp
similarity index 100%
rename from xo-alloc2/include/xo/alloc2/AllocInfo.hpp
rename to xo-arena/include/xo/arena/AllocInfo.hpp
diff --git a/xo-alloc2/include/xo/alloc2/arena/ArenaConfig.hpp b/xo-arena/include/xo/arena/ArenaConfig.hpp
similarity index 97%
rename from xo-alloc2/include/xo/alloc2/arena/ArenaConfig.hpp
rename to xo-arena/include/xo/arena/ArenaConfig.hpp
index fcd95347..4d79637b 100644
--- a/xo-alloc2/include/xo/alloc2/arena/ArenaConfig.hpp
+++ b/xo-arena/include/xo/arena/ArenaConfig.hpp
@@ -6,7 +6,6 @@
 #pragma once
 
 #include "AllocHeaderConfig.hpp"
-//#include "alloc/AllocError.hpp"
 #include <string>
 #include <cstdint>
 
diff --git a/xo-alloc2/include/xo/alloc2/arena/DArena.hpp b/xo-arena/include/xo/arena/DArena.hpp
similarity index 98%
rename from xo-alloc2/include/xo/alloc2/arena/DArena.hpp
rename to xo-arena/include/xo/arena/DArena.hpp
index 45556d9f..f9c2e3c6 100644
--- a/xo-alloc2/include/xo/alloc2/arena/DArena.hpp
+++ b/xo-arena/include/xo/arena/DArena.hpp
@@ -8,7 +8,7 @@
 #include "ArenaConfig.hpp"
 #include "AllocError.hpp"
 #include "AllocInfo.hpp"
-#include <xo/facet/typeseq.hpp>
+#include <xo/reflectutil/typeseq.hpp>
 
 namespace xo {
     namespace mm {
@@ -46,7 +46,7 @@ namespace xo {
             /** @brief type for allocation header (if enabled) **/
             using header_type = AllocHeader;
             /** integer identifying a type (see xo::facet::typeid<T>()) **/
-            using typeseq = xo::facet::typeseq;
+            using typeseq = xo::reflect::typeseq;
 
             /** @brief mode argument for @ref _alloc **/
             enum class alloc_mode : uint8_t {
@@ -280,7 +280,7 @@ namespace xo {
         static T *
         construct_with(DArena & ialloc, Args&&... args)
         {
-            using xo::facet::typeseq;
+            using xo::reflect::typeseq;
 
             typeseq t = typeseq::id<T>();
             std::byte * mem = ialloc.alloc(t, sizeof(T));
diff --git a/xo-alloc2/include/xo/alloc2/arena/DArenaIterator.hpp b/xo-arena/include/xo/arena/DArenaIterator.hpp
similarity index 100%
rename from xo-alloc2/include/xo/alloc2/arena/DArenaIterator.hpp
rename to xo-arena/include/xo/arena/DArenaIterator.hpp
diff --git a/xo-alloc2/include/xo/alloc2/cmpresult.hpp b/xo-arena/include/xo/arena/cmpresult.hpp
similarity index 100%
rename from xo-alloc2/include/xo/alloc2/cmpresult.hpp
rename to xo-arena/include/xo/arena/cmpresult.hpp
diff --git a/xo-alloc2/include/xo/alloc2/padding.hpp b/xo-arena/include/xo/arena/padding.hpp
similarity index 100%
rename from xo-alloc2/include/xo/alloc2/padding.hpp
rename to xo-arena/include/xo/arena/padding.hpp
diff --git a/xo-alloc2/src/alloc2/AllocError.cpp b/xo-arena/src/arena/AllocError.cpp
similarity index 100%
rename from xo-alloc2/src/alloc2/AllocError.cpp
rename to xo-arena/src/arena/AllocError.cpp
diff --git a/xo-alloc2/src/alloc2/AllocInfo.cpp b/xo-arena/src/arena/AllocInfo.cpp
similarity index 100%
rename from xo-alloc2/src/alloc2/AllocInfo.cpp
rename to xo-arena/src/arena/AllocInfo.cpp
diff --git a/xo-arena/src/arena/CMakeLists.txt b/xo-arena/src/arena/CMakeLists.txt
new file mode 100644
index 00000000..111bbe15
--- /dev/null
+++ b/xo-arena/src/arena/CMakeLists.txt
@@ -0,0 +1,24 @@
+# xo-arena/src/CMakeLists.txt
+
+set(SELF_LIB xo_arena)
+set(SELF_SRCS
+    cmpresult.cpp
+    AllocError.cpp
+    AllocInfo.cpp
+    DArena.cpp
+    DArenaIterator.cpp
+)
+
+xo_add_shared_library4(${SELF_LIB} ${PROJECT_NAME}Targets ${PROJECT_VERSION} 1 ${SELF_SRCS})
+xo_install_include_tree3(include/xo/arena)
+
+# ----------------------------------------------------------------
+# input dependencies
+#
+# NOTE: dependency set here must be kept consistent with
+#       xo-arena/cmake/xo_arenaConfig.cmake.in
+
+xo_dependency(${SELF_LIB} xo_reflectutil)
+xo_dependency(${SELF_LIB} indentlog)
+
+# end src/CMakeLists.txt
diff --git a/xo-alloc2/src/alloc2/DArena.cpp b/xo-arena/src/arena/DArena.cpp
similarity index 98%
rename from xo-alloc2/src/alloc2/DArena.cpp
rename to xo-arena/src/arena/DArena.cpp
index 82557e4b..5c0e3641 100644
--- a/xo-alloc2/src/alloc2/DArena.cpp
+++ b/xo-arena/src/arena/DArena.cpp
@@ -3,19 +3,19 @@
  *  @author Roland Conybeare, Dec 2025
  **/
 
-#include "alloc/AAllocator.hpp"
-#include "arena/DArena.hpp"
-#include "arena/DArenaIterator.hpp"
-#include "xo/alloc2/padding.hpp"
-#include "xo/indentlog/scope.hpp"
-#include "xo/indentlog/print/tag.hpp"
+//#include "alloc/AAllocator.hpp"
+#include "DArena.hpp"
+#include "DArenaIterator.hpp"
+#include <xo/arena/padding.hpp>
+#include <xo/indentlog/scope.hpp>
+#include <xo/indentlog/print/tag.hpp>
 #include <cassert>
 #include <sys/mman.h> // for ::munmap()
 #include <unistd.h> // for ::getpagesize()
 #include <string.h> // for ::memset()
 
 namespace xo {
-    using xo::facet::typeseq;
+    using xo::reflect::typeseq;
     using std::byte;
     using std::cerr;
     using std::endl;
diff --git a/xo-alloc2/src/alloc2/DArenaIterator.cpp b/xo-arena/src/arena/DArenaIterator.cpp
similarity index 98%
rename from xo-alloc2/src/alloc2/DArenaIterator.cpp
rename to xo-arena/src/arena/DArenaIterator.cpp
index b9873e31..931108bb 100644
--- a/xo-alloc2/src/alloc2/DArenaIterator.cpp
+++ b/xo-arena/src/arena/DArenaIterator.cpp
@@ -3,8 +3,8 @@
  *  @author Roland Conybeare, Dec 2025
  **/
 
-#include "arena/DArenaIterator.hpp"
-#include "arena/DArena.hpp"
+#include "DArenaIterator.hpp"
+#include "DArena.hpp"
 #include <xo/indentlog/scope.hpp>
 #include <xo/indentlog/print/tag.hpp>
 #include <cassert>
diff --git a/xo-alloc2/src/alloc2/cmpresult.cpp b/xo-arena/src/arena/cmpresult.cpp
similarity index 100%
rename from xo-alloc2/src/alloc2/cmpresult.cpp
rename to xo-arena/src/arena/cmpresult.cpp
diff --git a/xo-cmake/bin/scaffold-headeronly b/xo-cmake/bin/scaffold-headeronly
new file mode 100755
index 00000000..b4455677
--- /dev/null
+++ b/xo-cmake/bin/scaffold-headeronly
@@ -0,0 +1,282 @@
+#!/usr/bin/env bash
+#
+# scaffold-headeronly - Create a new xo library subdirectory
+#
+# Usage: scaffold-headeronly [--mode=headeronly|shared] <name>
+#   where <name> is the short name (e.g., "arena" creates "xo-arena")
+#
+
+set -euo pipefail
+
+usage() {
+    echo "Usage: $0 [--mode=headeronly|shared] <name>"
+    echo "  Creates xo-<name>/ with library scaffolding"
+    echo ""
+    echo "Options:"
+    echo "  --mode=headeronly  Create header-only library (default)"
+    echo "  --mode=shared      Create shared library with src/ directory"
+    echo ""
+    echo "Example: $0 arena"
+    echo "  Creates xo-arena/CMakeLists.txt"
+    echo "          xo-arena/cmake/xo-bootstrap-macros.cmake"
+    echo "          xo-arena/cmake/xo_arenaConfig.cmake.in"
+    echo "          xo-arena/include/xo/arena/"
+    echo ""
+    echo "Example: $0 --mode=shared mylib"
+    echo "  Creates xo-mylib/CMakeLists.txt"
+    echo "          xo-mylib/cmake/xo-bootstrap-macros.cmake"
+    echo "          xo-mylib/cmake/xo_mylibConfig.cmake.in"
+    echo "          xo-mylib/include/xo/mylib/"
+    echo "          xo-mylib/src/CMakeLists.txt"
+    exit 1
+}
+
+# Default mode
+MODE="headeronly"
+
+# Parse arguments
+while [[ $# -gt 0 ]]; do
+    case "$1" in
+        --mode=*)
+            MODE="${1#--mode=}"
+            if [[ "$MODE" != "headeronly" && "$MODE" != "shared" ]]; then
+                echo "Error: --mode must be 'headeronly' or 'shared'"
+                exit 1
+            fi
+            shift
+            ;;
+        --help|-h)
+            usage
+            ;;
+        -*)
+            echo "Error: unknown option $1"
+            usage
+            ;;
+        *)
+            break
+            ;;
+    esac
+done
+
+if [[ $# -ne 1 ]]; then
+    usage
+fi
+
+NAME="$1"
+
+# Validate name: alphanumeric and underscores only
+if [[ ! "$NAME" =~ ^[a-zA-Z][a-zA-Z0-9_]*$ ]]; then
+    echo "Error: name must start with letter and contain only alphanumeric/underscores"
+    exit 1
+fi
+
+# Derive names
+DIR_NAME="xo-${NAME}"
+LIB_NAME="xo_${NAME}"
+PROJECT_NAME="xo_${NAME}"
+
+# Get script directory to find umbrella root
+XO_UMBRELLA_ROOT=$(git rev-parse --show-toplevel)
+
+TARGET_DIR="${XO_UMBRELLA_ROOT}/${DIR_NAME}"
+
+if [[ -d "$TARGET_DIR" ]]; then
+    echo "Error: ${TARGET_DIR} already exists"
+    exit 1
+fi
+
+echo "Creating ${DIR_NAME} (${MODE}) in ${XO_UMBRELLA_ROOT}..."
+
+# Create directories
+mkdir -p "${TARGET_DIR}/cmake"
+mkdir -p "${TARGET_DIR}/include/xo/${NAME}"
+
+if [[ "$MODE" == "shared" ]]; then
+    mkdir -p "${TARGET_DIR}/src"
+fi
+
+# Create CMakeLists.txt (different content based on mode)
+if [[ "$MODE" == "headeronly" ]]; then
+    cat > "${TARGET_DIR}/CMakeLists.txt" << EOF
+# ${DIR_NAME}/CMakeLists.txt
+
+cmake_minimum_required(VERSION 3.10)
+
+project(${PROJECT_NAME} VERSION 1.0)
+enable_language(CXX)
+
+include(GNUInstallDirs)
+include(cmake/xo-bootstrap-macros.cmake)
+
+xo_cxx_toplevel_options3()
+
+# ----------------------------------------------------------------
+# c++ settings
+
+# one-time project-specific c++ flags. usually empty
+set(PROJECT_CXX_FLAGS "")
+add_definitions(\${PROJECT_CXX_FLAGS})
+
+# ----------------------------------------------------------------
+# output targets
+
+#add_subdirectory(utest)
+
+# ----------------------------------------------------------------
+# header-only library
+
+set(SELF_LIB ${LIB_NAME})
+xo_add_headeronly_library(\${SELF_LIB})
+xo_install_library4(\${SELF_LIB} \${PROJECT_NAME}Targets)
+xo_export_cmake_config(\${PROJECT_NAME} \${PROJECT_VERSION} \${PROJECT_NAME}Targets)
+
+# ----------------------------------------------------------------
+# input dependencies
+#
+# NOTE: dependency set here must be kept consistent with
+#       ${DIR_NAME}/cmake/${LIB_NAME}Config.cmake.in
+
+#xo_headeronly_dependency(\${SELF_LIB} xo_flatstring)
+
+# end CMakeLists.txt
+EOF
+else
+    # Shared library mode
+    cat > "${TARGET_DIR}/CMakeLists.txt" << EOF
+# ${DIR_NAME}/CMakeLists.txt
+
+cmake_minimum_required(VERSION 3.10)
+
+project(${PROJECT_NAME} VERSION 1.0)
+enable_language(CXX)
+
+include(GNUInstallDirs)
+include(cmake/xo-bootstrap-macros.cmake)
+
+xo_cxx_toplevel_options3()
+
+# ----------------------------------------------------------------
+# c++ settings
+
+# one-time project-specific c++ flags. usually empty
+set(PROJECT_CXX_FLAGS "")
+add_definitions(\${PROJECT_CXX_FLAGS})
+
+# ----------------------------------------------------------------
+# output targets
+
+add_subdirectory(src)
+#add_subdirectory(utest)
+
+# ----------------------------------------------------------------
+# cmake export
+
+xo_export_cmake_config(\${PROJECT_NAME} \${PROJECT_VERSION} \${PROJECT_NAME}Targets)
+
+# end CMakeLists.txt
+EOF
+fi
+
+# Create cmake/xo-bootstrap-macros.cmake
+cat > "${TARGET_DIR}/cmake/xo-bootstrap-macros.cmake" << EOF
+# ----------------------------------------------------------------
+# for example:
+#   $ PREFIX=/usr/local   # for example
+#   $ cmake -DCMAKE_MODULE_PATH=prefix -DCMAKE_INSTALL_PREFIX=\$PREFIX -B .build
+#
+# will get
+#   CMAKE_MODULE_PATH
+# from xo-cmake-config --cmake-module-path
+#
+# and expect .cmake macros in
+#   CMAKE_MODULE_PATH/xo_macros/xo_cxx.cmake
+# ----------------------------------------------------------------
+
+find_program(XO_CMAKE_CONFIG_EXECUTABLE NAMES xo-cmake-config REQUIRED)
+
+if (("\${CMAKE_MODULE_PATH}" STREQUAL "") OR ("\${CMAKE_MODULE_PATH}" STREQUAL "prefix"))
+    message(FATAL "could not find xo-cmake-config executable")
+endif()
+
+if (NOT XO_SUBMODULE_BUILD)
+    if (("\${CMAKE_MODULE_PATH}" STREQUAL "") OR ("\${CMAKE_MODULE_PATH}" STREQUAL prefix))
+        # default to typical install location for xo-project-macros
+        execute_process(COMMAND \${XO_CMAKE_CONFIG_EXECUTABLE} --cmake-module-path OUTPUT_VARIABLE CMAKE_MODULE_PATH)
+        message(STATUS "CMAKE_MODULE_PATH=\${CMAKE_MODULE_PATH}")
+    endif()
+endif()
+
+# needs to have been installed somewhere on CMAKE_MODULE_PATH,
+# (e.g. from xo-cmake with the same value for CMAKE_INSTALL_PREFIX)
+#
+include(xo_macros/xo_cxx)
+
+xo_cxx_bootstrap_message()
+EOF
+
+# Create cmake/xo_${NAME}Config.cmake.in
+cat > "${TARGET_DIR}/cmake/${LIB_NAME}Config.cmake.in" << EOF
+@PACKAGE_INIT@
+
+include(CMakeFindDependencyMacro)
+
+# note: changes to find_dependency() calls here
+#       must coordinate with xo_dependency() calls
+#       in CMakeLists.txt
+#
+#find_dependency(xo_flatstring)
+
+include("\${CMAKE_CURRENT_LIST_DIR}/@PROJECT_NAME@Targets.cmake")
+check_required_components("@PROJECT_NAME@")
+EOF
+
+# Create src/CMakeLists.txt for shared library mode
+if [[ "$MODE" == "shared" ]]; then
+    cat > "${TARGET_DIR}/src/CMakeLists.txt" << EOF
+# ${DIR_NAME}/src/CMakeLists.txt
+
+set(SELF_LIB ${LIB_NAME})
+set(SELF_SRCS
+    # Add source files here, e.g.:
+    # ${NAME}.cpp
+)
+
+xo_add_shared_library4(\${SELF_LIB} \${PROJECT_NAME}Targets \${PROJECT_VERSION} 1 \${SELF_SRCS})
+xo_install_include_tree3(include/xo/${NAME})
+
+# ----------------------------------------------------------------
+# input dependencies
+#
+# NOTE: dependency set here must be kept consistent with
+#       ${DIR_NAME}/cmake/${LIB_NAME}Config.cmake.in
+
+#xo_dependency(\${SELF_LIB} xo_indentlog)
+
+# end src/CMakeLists.txt
+EOF
+fi
+
+# Create placeholder .gitkeep in include dir
+touch "${TARGET_DIR}/include/xo/${NAME}/.gitkeep"
+
+echo ""
+echo "Created ${DIR_NAME}/ (${MODE}) with:"
+echo "  ${DIR_NAME}/CMakeLists.txt"
+echo "  ${DIR_NAME}/cmake/xo-bootstrap-macros.cmake"
+echo "  ${DIR_NAME}/cmake/${LIB_NAME}Config.cmake.in"
+echo "  ${DIR_NAME}/include/xo/${NAME}/"
+if [[ "$MODE" == "shared" ]]; then
+    echo "  ${DIR_NAME}/src/CMakeLists.txt"
+fi
+echo ""
+echo "Next steps:"
+if [[ "$MODE" == "headeronly" ]]; then
+    echo "  1. Add header files to ${DIR_NAME}/include/xo/${NAME}/"
+    echo "  2. Add ${DIR_NAME} to umbrella CMakeLists.txt"
+    echo "  3. Uncomment dependencies as needed in CMakeLists.txt and Config.cmake.in"
+else
+    echo "  1. Add header files to ${DIR_NAME}/include/xo/${NAME}/"
+    echo "  2. Add source files to ${DIR_NAME}/src/ and update src/CMakeLists.txt SELF_SRCS"
+    echo "  3. Add ${DIR_NAME} to umbrella CMakeLists.txt"
+    echo "  4. Uncomment dependencies as needed in src/CMakeLists.txt and Config.cmake.in"
+fi
diff --git a/xo-facet/include/xo/facet/OObject.hpp b/xo-facet/include/xo/facet/OObject.hpp
index 93b532d7..37298fef 100644
--- a/xo-facet/include/xo/facet/OObject.hpp
+++ b/xo-facet/include/xo/facet/OObject.hpp
@@ -6,7 +6,7 @@
 #pragma once
 
 #include "facet_implementation.hpp"
-#include "typeseq.hpp"
+#include <xo/reflectutil/typeseq.hpp>
 #include <new>
 #include <cstring>
 #include <cstddef>
@@ -64,6 +64,7 @@ namespace xo {
             using DataType = DRepr;
             using DataPtr = DRepr*;
             using Opaque = void *;
+            using typeseq = xo::reflect::typeseq;
 
             /* required for vtable swapping to work */
             //static_assert(std::is_trivially_copyable_v<AFacet>);
diff --git a/xo-facet/utest/CMakeLists.txt b/xo-facet/utest/CMakeLists.txt
index 81ec6d99..eec41c06 100644
--- a/xo-facet/utest/CMakeLists.txt
+++ b/xo-facet/utest/CMakeLists.txt
@@ -8,6 +8,7 @@ set(UTEST_SRCS
 
 if (ENABLE_TESTING)
     xo_add_utest_executable(${UTEST_EXE} ${UTEST_SRCS})
+    xo_self_dependency(${UTEST_EXE} xo_arena)
     xo_external_target_dependency(${UTEST_EXE} Catch2 Catch2::Catch2)
 endif()
 
diff --git a/xo-gc/include/xo/gc/DX1Collector.hpp b/xo-gc/include/xo/gc/DX1Collector.hpp
index bde9f04d..33c9f56d 100644
--- a/xo-gc/include/xo/gc/DX1Collector.hpp
+++ b/xo-gc/include/xo/gc/DX1Collector.hpp
@@ -10,8 +10,8 @@
 #include "object_age.hpp"
 #include "role.hpp"
 #include <xo/alloc2/Allocator.hpp>
-#include <xo/alloc2/arena/ArenaConfig.hpp>
-#include <xo/alloc2/arena/DArena.hpp>
+#include <xo/arena/DArena.hpp>
+#include <xo/arena/ArenaConfig.hpp>
 #include <memory>
 #include <array>
 
diff --git a/xo-gc/include/xo/gc/DX1CollectorIterator.hpp b/xo-gc/include/xo/gc/DX1CollectorIterator.hpp
index af1e867a..98a1f1d2 100644
--- a/xo-gc/include/xo/gc/DX1CollectorIterator.hpp
+++ b/xo-gc/include/xo/gc/DX1CollectorIterator.hpp
@@ -7,8 +7,8 @@
 
 #include "AllocInfo.hpp"
 #include "generation.hpp"
-#include "arena/DArenaIterator.hpp"
-#include "cmpresult.hpp"
+#include <xo/arena/DArenaIterator.hpp>
+#include <xo/arena/cmpresult.hpp>
 
 namespace xo {
     namespace mm {
diff --git a/xo-gc/utest/DX1CollectorIterator.test.cpp b/xo-gc/utest/DX1CollectorIterator.test.cpp
index 58a498c5..99347fad 100644
--- a/xo-gc/utest/DX1CollectorIterator.test.cpp
+++ b/xo-gc/utest/DX1CollectorIterator.test.cpp
@@ -8,7 +8,7 @@
 #include "DX1CollectorIterator.hpp"
 #include "detail/IAllocator_DX1Collector.hpp"
 #include "detail/IAllocIterator_DX1CollectorIterator.hpp"
-#include "arena/ArenaConfig.hpp"
+#include <xo/arena/ArenaConfig.hpp>
 #include "padding.hpp"
 #include <xo/indentlog/scope.hpp>
 #include <xo/indentlog/print/tag.hpp>
diff --git a/xo-gc/utest/random_allocs.cpp b/xo-gc/utest/random_allocs.cpp
index 654c6c9a..1f7f833f 100644
--- a/xo-gc/utest/random_allocs.cpp
+++ b/xo-gc/utest/random_allocs.cpp
@@ -4,8 +4,8 @@
  **/
 
 #include "random_allocs.hpp"
-#include "arena/DArena.hpp"
-#include "padding.hpp"
+#include <xo/arena/DArena.hpp>
+#include <xo/arena/padding.hpp>
 #include <xo/indentlog/scope.hpp>
 #include <xo/indentlog/print/tag.hpp>
 #include <catch2/catch.hpp>
diff --git a/xo-object2/include/xo/object2/DList.hpp b/xo-object2/include/xo/object2/DList.hpp
index f6296933..dc0729bf 100644
--- a/xo-object2/include/xo/object2/DList.hpp
+++ b/xo-object2/include/xo/object2/DList.hpp
@@ -8,6 +8,7 @@
 #include <xo/gc/GCObject.hpp>
 //#include "xo/alloc2/gcobject/RGCObject.hpp"
 #include <xo/facet/obj.hpp>
+#include <xo/indentlog/print/ppindentinfo.hpp>
 
 namespace xo {
     namespace scm {
@@ -16,6 +17,7 @@ namespace xo {
             using size_type = std::size_t;
             using AGCObject = xo::mm::AGCObject;
             using AAllocator = xo::mm::AAllocator;
+            using ppindentinfo = xo::print::ppindentinfo;
 
             DList(xo::obj<AGCObject> h,
                   DList * r) : head_{h}, rest_{r} {}
diff --git a/xo-object2/src/object2/DList.cpp b/xo-object2/src/object2/DList.cpp
index ea725773..65b18a69 100644
--- a/xo-object2/src/object2/DList.cpp
+++ b/xo-object2/src/object2/DList.cpp
@@ -4,6 +4,7 @@
  **/
 
 #include "DList.hpp"
+#include <xo/indentlog/print/pretty.hpp>
 #include <xo/indentlog/print/tag.hpp>
 
 namespace xo {
@@ -84,7 +85,6 @@ namespace xo {
             return l->head_;
         }
 
-#ifdef NOT_YET
         bool
         DList::pretty(const ppindentinfo & ppii) const
         {
@@ -95,19 +95,24 @@ namespace xo {
             ppstate * pps = ppii.pps();
 
             if (ppii.upto()) {
-/* perhaps print on one line */
-                if (!pps->print_upto("(")
+                /* perhaps print on one line */
+                if (!pps->print_upto("(...)"))
                     return false;
 
+#ifdef NOT_YET
                 /* TODO: probably use iterators here, when available */
                 const DList * l = this;
                 while (!l->is_empty()) {
                     obj<APrintable>(l->head_.data());
 
                 }
+#endif
+                return true;
+            } else {
+                pps->write("(...)");
+                return false;
             }
         }
-#endif
 
     } /*namespace scm*/
 } /*namespace xo*/
diff --git a/xo-object2/utest/X1Collector.test.cpp b/xo-object2/utest/X1Collector.test.cpp
index 1174635c..8b37c8ab 100644
--- a/xo-object2/utest/X1Collector.test.cpp
+++ b/xo-object2/utest/X1Collector.test.cpp
@@ -16,8 +16,8 @@
 #include <xo/gc/detail/IAllocator_DX1Collector.hpp>
 #include <xo/gc/detail/ICollector_DX1Collector.hpp>
 
-#include <xo/alloc2/AllocInfo.hpp>
-#include <xo/alloc2/padding.hpp>
+#include <xo/arena/AllocInfo.hpp>
+#include <xo/arena/padding.hpp>
 
 #include <xo/indentlog/scope.hpp>
 #include <xo/indentlog/print/tag.hpp>
diff --git a/xo-ratio/utest/CMakeLists.txt b/xo-ratio/utest/CMakeLists.txt
index f1ebac58..81379c30 100644
--- a/xo-ratio/utest/CMakeLists.txt
+++ b/xo-ratio/utest/CMakeLists.txt
@@ -20,6 +20,7 @@ if (ENABLE_TESTING)
     xo_headeronly_dependency(${SELF_EXE} xo_reflectutil)
     xo_dependency(${SELF_EXE} randomgen)
     xo_dependency(${SELF_EXE} indentlog)
+    xo_dependency(${SELF_EXE} xo_flatstring)
     xo_external_target_dependency(${SELF_EXE} Catch2 Catch2::Catch2)
 endif()