diff --git a/.github/workflows/code-review.yml b/.github/workflows/code-review.yml
index 5d94a0a712..588cee14fc 100644
--- a/.github/workflows/code-review.yml
+++ b/.github/workflows/code-review.yml
@@ -7,6 +7,8 @@ on:
 jobs:
   qoder-review:
     runs-on: ubuntu-latest
+    env:
+      QODER_PERSONAL_ACCESS_TOKEN: ${{ secrets.QODER_PERSONAL_ACCESS_TOKEN }}
     permissions:
       contents: read
       pull-requests: write
@@ -14,14 +16,20 @@ jobs:
     
     steps:
       - name: Checkout repository
+        if: ${{ env.QODER_PERSONAL_ACCESS_TOKEN != '' }}
         uses: actions/checkout@v4
         with:
           fetch-depth: 0
       
       - name: Run Qoder Code Review
+        if: ${{ env.QODER_PERSONAL_ACCESS_TOKEN != '' }}
         uses: QoderAI/qoder-action@v0
         with:
-          qoder_personal_access_token: ${{ secrets.QODER_PERSONAL_ACCESS_TOKEN }}
+          qoder_personal_access_token: ${{ env.QODER_PERSONAL_ACCESS_TOKEN }}
           prompt: |
             /review-pr
             REPO:${{ github.repository }} PR_NUMBER:${{ github.event.pull_request.number }}
+
+      - name: Skip Qoder Code Review
+        if: ${{ env.QODER_PERSONAL_ACCESS_TOKEN == '' }}
+        run: echo "Qoder review skipped because QODER_PERSONAL_ACCESS_TOKEN is unavailable."
diff --git a/.gitmodules b/.gitmodules
index acc910c38d..5a4998c24b 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -6,3 +6,7 @@
 	path = extern/yalantinglibs
 	url = https://github.com/alibaba/yalantinglibs.git
 	branch = v0.5.7
+[submodule "extern/ubdiag"]
+	path = extern/ubdiag
+	url = https://atomgit.com/liusiyu60/ubdiag
+	branch = fix/shm-probe-fastpath
diff --git a/extern/ubdiag b/extern/ubdiag
new file mode 160000
index 0000000000..7deea5f897
--- /dev/null
+++ b/extern/ubdiag
@@ -0,0 +1 @@
+Subproject commit 7deea5f89786784a2e2aa074d315a0a8e2561963
diff --git a/mooncake-common/FindUbDiag.cmake b/mooncake-common/FindUbDiag.cmake
new file mode 100644
index 0000000000..b4e7a53594
--- /dev/null
+++ b/mooncake-common/FindUbDiag.cmake
@@ -0,0 +1,277 @@
+# FindUbDiag.cmake Resolves UbDiag::ubdiag_lib with a three-layer fallback: 1.
+# Submodule (extern/ubdiag) — add_subdirectory if present 2. System package —
+# find_package(UbDiag QUIET) 3. Mock header  — mooncake-common/ubdiag-mock/
+# (no-op PerfPoint)
+#
+# Usage: include(${CMAKE_SOURCE_DIR}/mooncake-common/FindUbDiag.cmake)
+# target_link_libraries(your_target PRIVATE UbDiag::ubdiag_lib)
+
+if(TARGET UbDiag::ubdiag_lib)
+  return()
+endif()
+
+option(MOONCAKE_UBDIAG_BUILD_CLI
+  "Enable UbDiag CLI integration for vendored or system UbDiag" ON)
+option(MOONCAKE_UBDIAG_L1_SHARED
+  "Build vendored UbDiag as libubdiag.so so Mooncake and the CLI use one SDK" ON)
+option(MOONCAKE_UBDIAG_ENABLE_PERCENTILE
+  "Enable vendored UbDiag P99/P999/P9999 percentile calculation for Mooncake PerfPoint" ON)
+option(MOONCAKE_UBDIAG_ENABLE_PERFLOG
+  "Enable vendored UbDiag PerfLog timestamp logging for Mooncake PerfPoint" ON)
+option(MOONCAKE_UBDIAG_PERFPOINT_ONLY
+  "Disable vendored UbDiag OB/MemPoint/CachePoint extensions; keep Mooncake PerfPoint/P99/PerfLog/CSV" ON)
+option(MOONCAKE_UBDIAG_DISABLE_SYSTEM
+  "Skip Layer 2 system-package lookup, used only for forced mock verification" OFF)
+
+function(_mooncake_ubdiag_write_rpm_manifest layer cli_path library_path config_path)
+  set(_manifest "${CMAKE_BINARY_DIR}/mooncake_ubdiag_rpm.env")
+  file(WRITE "${_manifest}" "MOONCAKE_UBDIAG_LAYER=${layer}\n")
+  file(APPEND "${_manifest}" "MOONCAKE_UBDIAG_CLI_PATH=${cli_path}\n")
+  file(APPEND "${_manifest}" "MOONCAKE_UBDIAG_LIBRARY_PATH=${library_path}\n")
+  file(APPEND "${_manifest}" "MOONCAKE_UBDIAG_CONFIG_PATH=${config_path}\n")
+  set(MOONCAKE_UBDIAG_RPM_MANIFEST "${_manifest}"
+      CACHE FILEPATH "UbDiag RPM packaging manifest generated by Mooncake" FORCE)
+  set(MOONCAKE_UBDIAG_ACTIVE_LAYER "${layer}"
+      CACHE STRING "Active UbDiag integration layer: submodule, system, or mock" FORCE)
+endfunction()
+
+function(_mooncake_ubdiag_get_imported_location target out_var)
+  set(_location_props IMPORTED_LOCATION IMPORTED_LOCATION_NOCONFIG)
+  get_target_property(_configs ${target} IMPORTED_CONFIGURATIONS)
+  if(NOT _configs OR _configs MATCHES "-NOTFOUND$")
+    set(_configs)
+  endif()
+  foreach(_config IN LISTS _configs)
+    string(TOUPPER "${_config}" _config_upper)
+    list(APPEND _location_props "IMPORTED_LOCATION_${_config_upper}")
+  endforeach()
+  list(APPEND _location_props
+       IMPORTED_LOCATION_RELEASE
+       IMPORTED_LOCATION_RELWITHDEBINFO
+       IMPORTED_LOCATION_MINSIZEREL
+       IMPORTED_LOCATION_DEBUG)
+
+  foreach(_prop IN LISTS _location_props)
+    get_target_property(_location ${target} ${_prop})
+    if(_location AND NOT _location MATCHES "-NOTFOUND$")
+      set(${out_var} "${_location}" PARENT_SCOPE)
+      return()
+    endif()
+  endforeach()
+
+  set(${out_var} "" PARENT_SCOPE)
+endfunction()
+
+function(_mooncake_ubdiag_require_submodule_file source_dir relative_path)
+  set(_required_file "${source_dir}/${relative_path}")
+  if(EXISTS "${_required_file}")
+    return()
+  endif()
+
+  # A pull updates the parent gitlink but does not repair deleted files in an
+  # already checked-out submodule. Restore only the required tracked file and
+  # leave every other local UbDiag change untouched.
+  find_program(_MOONCAKE_UBDIAG_GIT_EXECUTABLE NAMES git)
+  if(_MOONCAKE_UBDIAG_GIT_EXECUTABLE AND EXISTS "${source_dir}/.git")
+    execute_process(
+      COMMAND "${_MOONCAKE_UBDIAG_GIT_EXECUTABLE}"
+              -C "${source_dir}" checkout -- "${relative_path}"
+      RESULT_VARIABLE _restore_result
+      OUTPUT_QUIET
+      ERROR_QUIET)
+    if(_restore_result EQUAL 0 AND EXISTS "${_required_file}")
+      message(STATUS "UbDiag: restored missing tracked file ${relative_path}")
+      return()
+    endif()
+  endif()
+
+  message(FATAL_ERROR
+    "UbDiag L1 submodule is incomplete: ${_required_file} is missing.\n"
+    "Restore the recorded submodule contents with:\n"
+    "  git submodule sync --recursive\n"
+    "  git submodule update --init --checkout extern/ubdiag")
+endfunction()
+
+# Layer 1: Submodule (same pattern as extern/pybind11). UbDiag's generic
+# BUILD_TESTS / BUILD_EXAMPLES default to ON and collide with Mooncake option
+# names, so temporarily narrow them only while adding the submodule.
+if(EXISTS "${CMAKE_SOURCE_DIR}/extern/ubdiag/CMakeLists.txt")
+  file(STRINGS "${CMAKE_SOURCE_DIR}/extern/ubdiag/CMakeLists.txt"
+       _MOONCAKE_UBDIAG_PACKAGE_CONFIG_REFS
+       REGEX "UbDiagConfig\\.cmake\\.in")
+  if(_MOONCAKE_UBDIAG_PACKAGE_CONFIG_REFS)
+    _mooncake_ubdiag_require_submodule_file(
+      "${CMAKE_SOURCE_DIR}/extern/ubdiag" "cmake/UbDiagConfig.cmake.in")
+  endif()
+
+  set(_MOONCAKE_UBDIAG_SAVED_BUILD_EXAMPLES "${BUILD_EXAMPLES}")
+  set(_MOONCAKE_UBDIAG_HAD_BUILD_EXAMPLES_CACHE FALSE)
+  if(DEFINED CACHE{BUILD_EXAMPLES})
+    set(_MOONCAKE_UBDIAG_HAD_BUILD_EXAMPLES_CACHE TRUE)
+    get_property(_MOONCAKE_UBDIAG_BUILD_EXAMPLES_HELP CACHE BUILD_EXAMPLES PROPERTY HELPSTRING)
+  endif()
+  set(_MOONCAKE_UBDIAG_SAVED_BUILD_TESTS "${BUILD_TESTS}")
+  set(_MOONCAKE_UBDIAG_HAD_BUILD_TESTS_CACHE FALSE)
+  if(DEFINED CACHE{BUILD_TESTS})
+    set(_MOONCAKE_UBDIAG_HAD_BUILD_TESTS_CACHE TRUE)
+    get_property(_MOONCAKE_UBDIAG_BUILD_TESTS_HELP CACHE BUILD_TESTS PROPERTY HELPSTRING)
+  endif()
+  set(BUILD_EXAMPLES OFF)
+  set(BUILD_EXAMPLES OFF CACHE BOOL "Disable UbDiag examples when vendored by Mooncake" FORCE)
+  set(BUILD_TESTS OFF)
+  set(BUILD_TESTS OFF CACHE BOOL "Disable UbDiag tests when vendored by Mooncake" FORCE)
+  if(MOONCAKE_UBDIAG_L1_SHARED)
+    set(UBDIAG_BUILD_SHARED ON CACHE BOOL "Build vendored UbDiag as a shared library" FORCE)
+  endif()
+  if(MOONCAKE_UBDIAG_ENABLE_PERCENTILE)
+    set(ENABLE_PERCENTILE ON CACHE BOOL "Enable vendored UbDiag percentile calculation" FORCE)
+  endif()
+  if(MOONCAKE_UBDIAG_ENABLE_PERFLOG)
+    set(ENABLE_PERFLOG ON CACHE BOOL "Enable vendored UbDiag PerfLog support" FORCE)
+  endif()
+  if(MOONCAKE_UBDIAG_PERFPOINT_ONLY)
+    set(ENABLE_OB_MEMORY OFF CACHE BOOL "Disable vendored UbDiag eBPF memory observation" FORCE)
+    set(ENABLE_OB_CACHE OFF CACHE BOOL "Disable vendored UbDiag cache observation" FORCE)
+    set(ENABLE_MEMPOINT OFF CACHE BOOL "Disable vendored UbDiag MemPoint observation" FORCE)
+    set(UBDIAG_ENABLE_CACHEPOINT OFF CACHE BOOL "Disable vendored UbDiag CachePoint observation" FORCE)
+  endif()
+
+  add_subdirectory(${CMAKE_SOURCE_DIR}/extern/ubdiag
+                   ${CMAKE_BINARY_DIR}/extern/ubdiag_build EXCLUDE_FROM_ALL)
+
+  if(_MOONCAKE_UBDIAG_HAD_BUILD_EXAMPLES_CACHE)
+    set(BUILD_EXAMPLES "${_MOONCAKE_UBDIAG_SAVED_BUILD_EXAMPLES}"
+        CACHE BOOL "${_MOONCAKE_UBDIAG_BUILD_EXAMPLES_HELP}" FORCE)
+  else()
+    unset(BUILD_EXAMPLES CACHE)
+  endif()
+  set(BUILD_EXAMPLES "${_MOONCAKE_UBDIAG_SAVED_BUILD_EXAMPLES}")
+  if(_MOONCAKE_UBDIAG_HAD_BUILD_TESTS_CACHE)
+    set(BUILD_TESTS "${_MOONCAKE_UBDIAG_SAVED_BUILD_TESTS}"
+        CACHE BOOL "${_MOONCAKE_UBDIAG_BUILD_TESTS_HELP}" FORCE)
+  else()
+    unset(BUILD_TESTS CACHE)
+  endif()
+  set(BUILD_TESTS "${_MOONCAKE_UBDIAG_SAVED_BUILD_TESTS}")
+
+  if(TARGET ubdiag_lib)
+    set(_MOONCAKE_UBDIAG_SOURCE_DIR "${CMAKE_SOURCE_DIR}/extern/ubdiag")
+    # ubdiag's CMake uses CMAKE_SOURCE_DIR instead of CMAKE_CURRENT_SOURCE_DIR
+    # for its include paths. When consumed via add_subdirectory from Mooncake,
+    # CMAKE_SOURCE_DIR points to Mooncake's root, not ubdiag's. Fix it here.
+    target_include_directories(ubdiag_lib PUBLIC
+      $<BUILD_INTERFACE:${_MOONCAKE_UBDIAG_SOURCE_DIR}/include>
+      $<INSTALL_INTERFACE:include>)
+
+    foreach(_MOONCAKE_UBDIAG_LIB_TARGET
+            ubdiag_logger ubdiag_manager_lib ubdiag_runtime_lib ubdiag_bpf_loader)
+      if(TARGET ${_MOONCAKE_UBDIAG_LIB_TARGET})
+        target_include_directories(${_MOONCAKE_UBDIAG_LIB_TARGET} PUBLIC
+          $<BUILD_INTERFACE:${_MOONCAKE_UBDIAG_SOURCE_DIR}/include>
+          $<BUILD_INTERFACE:${_MOONCAKE_UBDIAG_SOURCE_DIR}/src>)
+      endif()
+    endforeach()
+
+    if(TARGET ubdiag)
+      target_include_directories(ubdiag PRIVATE
+        ${_MOONCAKE_UBDIAG_SOURCE_DIR}/include
+        ${_MOONCAKE_UBDIAG_SOURCE_DIR}/src
+        ${_MOONCAKE_UBDIAG_SOURCE_DIR}/src/cli)
+      if(MOONCAKE_UBDIAG_BUILD_CLI AND NOT TARGET mooncake_ubdiag_cli)
+        add_custom_target(mooncake_ubdiag_cli ALL DEPENDS ubdiag)
+      endif()
+    elseif(MOONCAKE_UBDIAG_BUILD_CLI)
+      message(WARNING "UbDiag: extern/ubdiag does not define the ubdiag CLI target")
+    endif()
+
+    add_library(UbDiag::ubdiag_lib ALIAS ubdiag_lib)
+    _mooncake_ubdiag_write_rpm_manifest(
+      "submodule"
+      "${CMAKE_BINARY_DIR}/extern/ubdiag_build/src/cli/ubdiag"
+      "${CMAKE_BINARY_DIR}/extern/ubdiag_build/src/sdk/libubdiag.so"
+      "${CMAKE_SOURCE_DIR}/extern/ubdiag/config/ubdiag.conf.example")
+    message(STATUS "UbDiag: using submodule (extern/ubdiag, CLI=${MOONCAKE_UBDIAG_BUILD_CLI})")
+    return()
+  endif()
+endif()
+
+# Layer 2: System package — only search standard system library paths
+# Using NO_DEFAULT_PATH + explicit PATHS to prevent cmake from recursively
+# searching CMAKE_SYSTEM_PREFIX_PATH subdirectories (e.g., UbDiag_bak, build artifacts)
+if(NOT MOONCAKE_UBDIAG_DISABLE_SYSTEM)
+  find_package(UbDiag QUIET
+      NO_DEFAULT_PATH
+      PATHS
+        /usr/lib64/cmake
+        /usr/local/lib64/cmake
+        /usr/lib/cmake
+        /usr/local/lib/cmake)
+  if(TARGET UbDiag::ubdiag_lib)
+    _mooncake_ubdiag_get_imported_location(UbDiag::ubdiag_lib _MOONCAKE_UBDIAG_SYSTEM_LIBRARY)
+
+    set(_MOONCAKE_UBDIAG_CLI_HINTS)
+    set(_MOONCAKE_UBDIAG_CONFIG_HINTS)
+    if(_MOONCAKE_UBDIAG_SYSTEM_LIBRARY)
+      get_filename_component(_MOONCAKE_UBDIAG_SYSTEM_LIB_DIR
+                             "${_MOONCAKE_UBDIAG_SYSTEM_LIBRARY}" DIRECTORY)
+      get_filename_component(_MOONCAKE_UBDIAG_SYSTEM_PREFIX
+                             "${_MOONCAKE_UBDIAG_SYSTEM_LIB_DIR}/.." ABSOLUTE)
+      list(APPEND _MOONCAKE_UBDIAG_CLI_HINTS
+           "${_MOONCAKE_UBDIAG_SYSTEM_PREFIX}/bin")
+      list(APPEND _MOONCAKE_UBDIAG_CONFIG_HINTS
+           "${_MOONCAKE_UBDIAG_SYSTEM_PREFIX}/etc/ubdiag")
+    endif()
+
+    find_program(MOONCAKE_UBDIAG_SYSTEM_CLI
+                 NAMES ubdiag
+                 HINTS ${_MOONCAKE_UBDIAG_CLI_HINTS}
+                 PATHS /usr/bin /usr/local/bin
+                 NO_DEFAULT_PATH)
+    if(MOONCAKE_UBDIAG_SYSTEM_CLI
+       AND NOT MOONCAKE_UBDIAG_SYSTEM_CLI MATCHES "-NOTFOUND$")
+      set(_MOONCAKE_UBDIAG_SYSTEM_CLI "${MOONCAKE_UBDIAG_SYSTEM_CLI}")
+      if(MOONCAKE_UBDIAG_BUILD_CLI AND NOT TARGET UbDiag::ubdiag_cli)
+        add_executable(UbDiag::ubdiag_cli IMPORTED GLOBAL)
+        set_target_properties(UbDiag::ubdiag_cli PROPERTIES
+                              IMPORTED_LOCATION "${_MOONCAKE_UBDIAG_SYSTEM_CLI}")
+      endif()
+      if(MOONCAKE_UBDIAG_BUILD_CLI AND NOT TARGET mooncake_ubdiag_cli)
+        add_custom_target(mooncake_ubdiag_cli ALL
+                          DEPENDS "${_MOONCAKE_UBDIAG_SYSTEM_CLI}")
+      endif()
+    else()
+      set(_MOONCAKE_UBDIAG_SYSTEM_CLI "")
+      if(MOONCAKE_UBDIAG_BUILD_CLI)
+        message(WARNING "UbDiag: system package found, but ubdiag CLI was not found under standard system paths")
+      endif()
+    endif()
+
+    find_file(MOONCAKE_UBDIAG_SYSTEM_CONFIG
+              NAMES ubdiag.conf
+              HINTS ${_MOONCAKE_UBDIAG_CONFIG_HINTS}
+              PATHS /etc/ubdiag /usr/local/etc/ubdiag
+              NO_DEFAULT_PATH)
+    if(MOONCAKE_UBDIAG_SYSTEM_CONFIG
+       AND NOT MOONCAKE_UBDIAG_SYSTEM_CONFIG MATCHES "-NOTFOUND$")
+      set(_MOONCAKE_UBDIAG_SYSTEM_CONFIG "${MOONCAKE_UBDIAG_SYSTEM_CONFIG}")
+    else()
+      set(_MOONCAKE_UBDIAG_SYSTEM_CONFIG "")
+    endif()
+
+    _mooncake_ubdiag_write_rpm_manifest(
+      "system"
+      "${_MOONCAKE_UBDIAG_SYSTEM_CLI}"
+      "${_MOONCAKE_UBDIAG_SYSTEM_LIBRARY}"
+      "${_MOONCAKE_UBDIAG_SYSTEM_CONFIG}")
+    message(STATUS "UbDiag: using system package (CLI=${_MOONCAKE_UBDIAG_SYSTEM_CLI})")
+    return()
+  endif()
+endif()
+
+# Layer 3: Mock fallback (no-op PerfPoint, guarantees compilation)
+add_library(ubdiag_mock INTERFACE)
+target_include_directories(
+  ubdiag_mock INTERFACE ${CMAKE_SOURCE_DIR}/mooncake-common/ubdiag-mock)
+add_library(UbDiag::ubdiag_lib ALIAS ubdiag_mock)
+_mooncake_ubdiag_write_rpm_manifest("mock" "" "" "")
+message(STATUS "UbDiag: using mock (no-op PerfPoint)")
diff --git a/mooncake-common/common.cmake b/mooncake-common/common.cmake
index eefa33bdb4..b2a56acc67 100644
--- a/mooncake-common/common.cmake
+++ b/mooncake-common/common.cmake
@@ -89,7 +89,6 @@ option(USE_UB "option for using UB protocol transport" OFF)
 option(USE_SUNRISE "option for enabling gpu features for Sunrise GPU with Tang runtime" OFF)
 
 if (USE_UB)
-  add_compile_definitions(USE_UB)
   message(STATUS "ub transport is enabled")
   include(${CMAKE_CURRENT_LIST_DIR}/FindUrma.cmake)
 endif()
diff --git a/mooncake-common/ubdiag-mock/README.md b/mooncake-common/ubdiag-mock/README.md
new file mode 100644
index 0000000000..8e98b03e00
--- /dev/null
+++ b/mooncake-common/ubdiag-mock/README.md
@@ -0,0 +1,158 @@
+# UbDiag Mock — Mooncake 集成说明
+
+本目录是 Mooncake 项目的 UbDiag header-only mock，提供空操作的 PerfPoint，
+确保在未安装 UbDiag 的情况下 Mooncake 仍可正常编译。
+
+## 四种情况：用户拿到 Mooncake 后，每一步发生了什么
+
+### 情况 A：`git clone --recursive` — 完整 submodule 路径
+
+**Step 1 — git clone**：`--recursive` 触发 Git 读取 `.gitmodules`，自动拉取三个 submodule：
+```
+extern/pybind11/       ← 已拉取
+extern/yalantinglibs/  ← 已拉取
+extern/ubdiag/         ← 已拉取，commit f0a4a13（v0.4.0-56）
+```
+
+**Step 2 — cmake**：CMake 执行到 `FindUbDiag.cmake`，按顺序判断：
+```
+if(TARGET UbDiag::ubdiag_lib) → 否，第一次执行
+if(EXISTS "extern/ubdiag/CMakeLists.txt") → 是 → add_subdirectory(real ubdiag)
+```
+输出：`UbDiag: using submodule (extern/ubdiag)`，return。
+
+`EXCLUDE_FROM_ALL` 保证只编译 `ubdiag_lib` 自身，不编译它的 30+ 个单元测试和 examples。
+
+**Step 3 — make**：`real_client.cpp` 中 `#include "ubdiag/auto_perf.h"` 找到真实 UbDiag，`PerfPoint::Start()/End()` 走 SHM 写入，性能数据可被 `ubdiag watch` 实时采集。
+
+---
+
+### 情况 B：`git clone`（无 `--recursive`）— mock 回退路径
+
+**Step 1 — git clone**：只拉 Mooncake 自有代码。`extern/ubdiag/` 目录不存在。
+
+**Step 2 — cmake**：`FindUbDiag.cmake` 按顺序判断：
+```
+if(TARGET UbDiag::ubdiag_lib) → 否
+if(EXISTS "extern/ubdiag/CMakeLists.txt") → 否，目录不存在
+find_package(UbDiag QUIET) → 否，系统没装
+→ 走 Layer 3：创建 header-only INTERFACE library
+```
+```cmake
+add_library(ubdiag_mock INTERFACE)     # 没有 .cpp，只暴露头文件路径
+add_library(UbDiag::ubdiag_lib ALIAS ubdiag_mock)
+```
+输出：`UbDiag: using mock (no-op PerfPoint)`。
+
+**Step 3 — make**：编译器展开 `PerfPoint::Start()` / `End()` 的两个空函数体：
+```cpp
+void Start() {}         // 编译器 -O1 以上：零指令
+void End(int = 0) {}    // 同上
+```
+93+ 处 `PerfPoint(...)` 调用全部优化为空操作。Mooncake 完整编译运行，无需 systemtap-sdt-dev、libbpf 等任何 UbDiag 依赖。
+
+---
+
+### 情况 C：已有 clone（无 submodule），后来补拉
+
+**Step 1 — git submodule update**：`extern/ubdiag/` 从不存在变为存在，Git 拉取 commit `f0a4a13`。
+
+```bash
+git submodule update --init --recursive
+```
+
+**Step 2 — 重新 cmake + make**：`FindUbDiag.cmake` 再次执行时 `EXISTS "extern/ubdiag/CMakeLists.txt"` 从 false 变成 true，Layer 1 命中。mock → submodule 切换自动完成，**不需要改任何 cmake 参数。**
+
+```bash
+cd build && cmake .. && make -j
+```
+
+---
+
+### 情况 D：CI 环境已系统预装 UbDiag
+
+**Step 1 — 系统预装**：运维已通过 RPM 或 `make install` 部署 `libubdiag.so` + `UbDiagConfig.cmake`。
+
+```bash
+cd ubdiag && bash build.sh -r && cd build && sudo make install
+```
+
+**Step 2 — cmake**：`FindUbDiag.cmake` 执行时 Layer 1 未命中（submodule 不存在），但 Layer 2 `find_package(UbDiag QUIET)` 成功发现系统 .so。输出 `UbDiag: using system package`。链接系统 .so，不编译 submodule。适用于 CI/CD 等已预装环境。
+
+## 用户操作指南
+
+作为 Mooncake 新用户，**你不需要做任何选择**。
+
+| 你的操作 | 结果 | 编译期日志 |
+|---|---|---|
+| `git clone --recursive` | 使用真实 UbDiag (submodule)，性能诊断完整可用 | `UbDiag: using submodule` |
+| `git clone`（不拉 submodule） | 使用本目录 mock，性能探针静默失效，核心功能不受影响 | `UbDiag: using mock` |
+| `git clone` + `git submodule update --init` | 从 mock 切换到 submodule | `UbDiag: using submodule` |
+| 系统已预装 UbDiag | 链接系统 .so，不编译 submodule | `UbDiag: using system package` |
+
+以上路径全自动，由 `mooncake-common/FindUbDiag.cmake` 检测路径是否存在决定，**不需要传任何 cmake 参数或环境变量**。
+
+### 路径 1：全新 clone（推荐，一步到位）
+
+```bash
+git clone --recursive <mooncake-repo-url>
+cd Mooncake && mkdir build && cd build
+cmake .. && make -j
+```
+
+`--recursive` 自动拉取三个 submodule（pybind11 / yalantinglibs / ubdiag），CMake 自动检测编译。
+
+### 路径 2：已有 clone，补拉 submodule
+
+```bash
+cd Mooncake
+git submodule update --init --recursive   # 拉取 ubdiag 等 submodule
+cd build && cmake .. && make -j
+```
+
+### 路径 3：不拉 submodule，也能编译（完全不使用 UbDiag）
+
+普通 `git clone`（不带 `--recursive`、不执行 `submodule update`）直接 cmake 编译即可，不需要做任何额外操作。
+CMake 自动回退至本目录的 header-only mock，编译期输出 `UbDiag: using mock`：
+- 所有 `PerfPoint` 调用编译为空操作，零运行时开销
+- 不依赖任何 UbDiag 的 .so 或头文件，不需要安装 systemtap-sdt-dev、libbpf 等依赖
+- Mooncake 核心功能完整运行，仅性能探针失效
+
+### 路径 4（可选）：系统预装 UbDiag
+
+```bash
+cd ubdiag && bash build.sh -r && cd build && sudo make install
+cd Mooncake && mkdir build && cd build
+cmake .. && make -j
+```
+
+CMake 通过 `find_package(UbDiag)` 自动发现系统已安装的库。适用于 CI/CD 等已预装环境。
+
+## 三层优先级
+
+```
+submodule (extern/ubdiag)  >  system package (find_package QUIET)  >  mock fallback (本目录)
+```
+
+每个 `include(FindUbDiag.cmake)` 开头有 `if(TARGET ...) return()`，多次 include 幂等。
+
+## 文件说明
+
+| 文件 | 用途 |
+|---|---|
+| `ubdiag/auto_perf.h` | Header-only mock，提供空操作 PerfPoint 和 PerfKey/PerfLevel 定义 |
+
+## PerfLevel 对齐
+
+本 mock 的 PerfLevel 枚举值与真实 UbDiag v0.4.0 保持一致：
+
+```cpp
+#include <cstdint>
+
+enum class PerfLevel : uint8_t {
+    SUB_SYSTEM  = 1,
+    KEY_MODULE  = 2,
+    MODULE      = 3,
+    DEBUG       = 4,
+};
+```
diff --git a/mooncake-common/ubdiag-mock/ubdiag/auto_perf.h b/mooncake-common/ubdiag-mock/ubdiag/auto_perf.h
new file mode 100644
index 0000000000..9a3f883729
--- /dev/null
+++ b/mooncake-common/ubdiag-mock/ubdiag/auto_perf.h
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: Apache-2.0
+// Copyright 2024-present Mooncake contributors
+//
+// Header-only mock for UbDiag. Provides no-op PerfPoint and PerfKey
+// definitions so the codebase compiles without the UbDiag library.
+// All perf instrumentation becomes a no-op.
+//
+// Differences from the real extern/ubdiag/include/ubdiag/auto_perf.h:
+//   - PerfKey values are all 0 (mock doesn't need unique slot indices).
+//   - No auto-init static initializer (mock has no SHM, no PerfManager).
+//   - PerfLevel / PerfPoint are no-ops (no SHM writes).
+
+#pragma once
+
+#include <cstdint>
+#include <type_traits>
+
+// Process the perf-key definition file to populate the PerfKey enum.
+// UBDIAG_PERF_DEF_FILE must be defined by the includer before this header.
+enum class PerfKey : int {
+// All keys map to 0 — mock PerfPoint ignores the key entirely.
+#define PERF_KEY_DEF(name, file, label) name = 0,
+#include UBDIAG_PERF_DEF_FILE
+#undef PERF_KEY_DEF
+};
+
+namespace UbDiag {
+
+enum class PerfLevel : uint8_t {
+    SUB_SYSTEM = 1,
+    KEY_MODULE = 2,
+    MODULE = 3,
+    DEBUG = 4,
+};
+
+class PerfPoint {
+   public:
+    explicit PerfPoint(uint32_t slotIndex, PerfLevel level) {
+        (void)slotIndex;
+        (void)level;
+    }
+
+    // Template constructor: accepts any enum type (zero-overhead in real
+    // UbDiag). Mock forwards to the no-op core constructor.
+    template <typename E, typename = std::enable_if_t<std::is_enum_v<E>>>
+    explicit PerfPoint(E key, PerfLevel level = PerfLevel::SUB_SYSTEM)
+        : PerfPoint(static_cast<uint32_t>(key), level) {}
+
+    ~PerfPoint() {}
+
+    void Start() {}
+    void End(int /*rc*/ = 0) {}
+    void Abandon() {}
+};
+
+}  // namespace UbDiag
diff --git a/mooncake-integration/CMakeLists.txt b/mooncake-integration/CMakeLists.txt
index 42e3d1d97c..5bd064941b 100644
--- a/mooncake-integration/CMakeLists.txt
+++ b/mooncake-integration/CMakeLists.txt
@@ -107,7 +107,7 @@ if(WITH_STORE)
                       store/engram_store_py.cpp integration_utils.h)
   set_target_properties(store PROPERTIES INSTALL_RPATH "$ORIGIN")
 
-  find_package(UbDiag REQUIRED)
+  include(${CMAKE_SOURCE_DIR}/mooncake-common/FindUbDiag.cmake)
   target_include_directories(store PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/store)
   target_link_libraries(store PRIVATE UbDiag::ubdiag_lib)
 
diff --git a/mooncake-p2p-store/CMakeLists.txt b/mooncake-p2p-store/CMakeLists.txt
index 5b9980de90..03efd1884a 100644
--- a/mooncake-p2p-store/CMakeLists.txt
+++ b/mooncake-p2p-store/CMakeLists.txt
@@ -2,7 +2,15 @@
 add_custom_target(build_p2p_store DEPENDS transfer_engine)
 add_custom_command(
     TARGET build_p2p_store
-    COMMAND bash build.sh ${CMAKE_CURRENT_BINARY_DIR} ${USE_ETCD} ${USE_REDIS} ${USE_HTTP} ${USE_ETCD_LEGACY} ${CMAKE_BINARY_DIR}
+    COMMAND bash build.sh
+            ${CMAKE_CURRENT_BINARY_DIR}
+            ${USE_ETCD}
+            ${USE_REDIS}
+            ${USE_HTTP}
+            ${USE_ETCD_LEGACY}
+            ${CMAKE_BINARY_DIR}
+            ${MOONCAKE_UBDIAG_ACTIVE_LAYER}
     WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+    VERBATIM
 )
 set_property(TARGET build_p2p_store PROPERTY EXCLUDE_FROM_ALL FALSE)
diff --git a/mooncake-p2p-store/build.sh b/mooncake-p2p-store/build.sh
index 520227b0c2..2fe3029e2d 100644
--- a/mooncake-p2p-store/build.sh
+++ b/mooncake-p2p-store/build.sh
@@ -13,8 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-if [ "$#" -ne 6 ]; then
-    echo "Usage: $0 TARGET_PATH USE_ETCD USE_REDIS USE_HTTP USE_ETCD_LEGACY BUILD_DIR"
+if [ "$#" -ne 7 ]; then
+    echo "Usage: $0 TARGET_PATH USE_ETCD USE_REDIS USE_HTTP USE_ETCD_LEGACY BUILD_DIR UBDIAG_LAYER"
     exit 1
 fi
 
@@ -24,6 +24,7 @@ USE_REDIS=$3
 USE_HTTP=$4
 USE_ETCD_LEGACY=$5
 BUILD_DIR=$6
+UBDIAG_LAYER=$7
 
 cd "src/p2pstore"
 if [ $? -ne 0 ]; then
@@ -35,7 +36,26 @@ EXT_LDFLAGS="-L$BUILD_DIR/mooncake-transfer-engine/src"
 EXT_LDFLAGS+=" -L$BUILD_DIR/mooncake-transfer-engine/src/common/base"
 EXT_LDFLAGS+=" -L$BUILD_DIR/mooncake-common"
 EXT_LDFLAGS+=" -L$BUILD_DIR/mooncake-common/src"
-EXT_LDFLAGS+=" -ltransfer_engine -lubdiag -lbase -lasio -lstdc++ -lnuma -lglog -libverbs -lmlx5 -ljsoncpp -lmooncake_common -lm"
+EXT_LDFLAGS+=" -ltransfer_engine"
+
+case "$UBDIAG_LAYER" in
+    submodule)
+        UBDIAG_LIB_DIR="$BUILD_DIR/extern/ubdiag_build/src/sdk"
+        EXT_LDFLAGS+=" -L$UBDIAG_LIB_DIR -lubdiag"
+        ;;
+    system)
+        EXT_LDFLAGS+=" -lubdiag"
+        ;;
+    mock)
+        echo "P2P Store: using UbDiag mock; skipping -lubdiag"
+        ;;
+    *)
+        echo "Error: Unknown UbDiag layer: $UBDIAG_LAYER"
+        exit 1
+        ;;
+esac
+
+EXT_LDFLAGS+=" -lbase -lasio -lstdc++ -lnuma -lglog -libverbs -lmlx5 -ljsoncpp -lmooncake_common -lm"
 
 if [ -d "/usr/local/cuda/lib64/stubs" ]; then
     EXT_LDFLAGS+=" -L/usr/local/cuda/lib64/stubs"
diff --git a/mooncake-store/src/CMakeLists.txt b/mooncake-store/src/CMakeLists.txt
index c6328b703e..e184329eb7 100644
--- a/mooncake-store/src/CMakeLists.txt
+++ b/mooncake-store/src/CMakeLists.txt
@@ -250,8 +250,8 @@ target_link_libraries(
          ${EXTRA_LIBS} ${SPDK_STATIC_LIBS} asio_shared mooncake_common
   PRIVATE transfer_engine)
 
-# UbDiag instrumentation
-find_package(UbDiag REQUIRED)
+# UbDiag instrumentation (resolved by FindUbDiag.cmake: submodule > system > mock)
+include(${CMAKE_SOURCE_DIR}/mooncake-common/FindUbDiag.cmake)
 target_link_libraries(mooncake_store PRIVATE UbDiag::ubdiag_lib)
 target_include_directories(mooncake_store PRIVATE
     ${CMAKE_CURRENT_SOURCE_DIR}/../../mooncake-integration/store)
diff --git a/mooncake-transfer-engine/src/CMakeLists.txt b/mooncake-transfer-engine/src/CMakeLists.txt
index 80c1cd0a3b..8704ed1533 100644
--- a/mooncake-transfer-engine/src/CMakeLists.txt
+++ b/mooncake-transfer-engine/src/CMakeLists.txt
@@ -1,5 +1,5 @@
 file(GLOB ENGINE_SOURCES "*.cpp")
-find_package(UbDiag REQUIRED)
+include(${CMAKE_SOURCE_DIR}/mooncake-common/FindUbDiag.cmake)
 add_subdirectory(common)
 add_subdirectory(transport)
 
@@ -164,6 +164,9 @@ if(USE_EFA)
   target_link_libraries(transfer_engine PUBLIC fabric efa_transport)
 endif()
 if(USE_UB)
+  target_compile_definitions(transfer_engine PUBLIC USE_UB)
   message(STATUS "Enabled USE_UB protocol support")
   target_link_libraries(transfer_engine PUBLIC ub_transport)
+  target_compile_definitions(transfer_engine PUBLIC USE_UB)
+  target_compile_definitions(ub_transport PRIVATE USE_UB)
 endif()
diff --git a/scripts/build_rpm.sh b/scripts/build_rpm.sh
index e41b241d26..08dd397637 100755
--- a/scripts/build_rpm.sh
+++ b/scripts/build_rpm.sh
@@ -10,10 +10,19 @@ set -x
 
 # Get build directory from environment variable or argument
 BUILD_DIR="${BUILD_DIR:-${1:-build}}"
-BUILD_DIR_ABS="$(pwd)/${BUILD_DIR}"
+if [[ "${BUILD_DIR}" = /* ]]; then
+    BUILD_DIR_ABS="${BUILD_DIR}"
+else
+    BUILD_DIR_ABS="$(pwd)/${BUILD_DIR}"
+fi
 
 # Get output directory from environment variable or argument
 OUTPUT_DIR="${OUTPUT_DIR:-${2:-rpm-output}}"
+if [[ "${OUTPUT_DIR}" = /* ]]; then
+    OUTPUT_DIR_ABS="${OUTPUT_DIR}"
+else
+    OUTPUT_DIR_ABS="$(pwd)/${OUTPUT_DIR}"
+fi
 
 # Detect current host architecture
 HOST_ARCH=$(uname -m)
@@ -44,12 +53,13 @@ export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:${BUILD_DIR_ABS}/mooncake-common:/usr/lo
 # Clean previous build
 echo "Cleaning previous RPM build..."
 rm -rf rpmbuild/
-rm -rf ${OUTPUT_DIR}/
+rm -rf ${OUTPUT_DIR_ABS}/
 
 # Function to build RPM for a specific platform
 build_rpm_for_platform() {
     local PLATFORM=$1
     local LIB_DIR="lib64"
+    local UBDIAG_RPM_FILES=""
     
     echo "Building RPM for platform: ${PLATFORM}"
     
@@ -68,7 +78,7 @@ build_rpm_for_platform() {
     mkdir -p rpmbuild/BUILDROOT/${PACKAGE_NAME}-${PACKAGE_VERSION}-${PACKAGE_RELEASE}.${PLATFORM}
     
     # Create target directories in BUILDROOT
-    mkdir -p rpmbuild/BUILDROOT/${PACKAGE_NAME}-${PACKAGE_VERSION}-${PACKAGE_RELEASE}.${PLATFORM}/{usr/{bin,${LIB_DIR},include},etc/mooncake}
+    mkdir -p rpmbuild/BUILDROOT/${PACKAGE_NAME}-${PACKAGE_VERSION}-${PACKAGE_RELEASE}.${PLATFORM}/{usr/{bin,${LIB_DIR},include},etc/{mooncake,ubdiag}}
     
     # -------------------------------------------------------------------------
     # Copy executables
@@ -170,6 +180,109 @@ build_rpm_for_platform() {
     else
         echo "Warning: store.so not found in ${PLATFORM_BUILD_DIR}, skipping..."
     fi
+
+    # UbDiag runtime artifacts. L1 packages the vendored build output. L2 packages
+    # the customer-provided system UbDiag selected by FindUbDiag.cmake. The CLI
+    # and libubdiag must come from the same layer so feature flags and shared
+    # memory layout stay in sync. Do not package UbDiag headers or CMake package
+    # metadata here: Layer 2 must remain a customer-provided system package.
+    local UBDIAG_BUILD_DIR="${PLATFORM_BUILD_DIR}/extern/ubdiag_build"
+    local UBDIAG_RPM_MANIFEST="${PLATFORM_BUILD_DIR}/mooncake_ubdiag_rpm.env"
+    local MOONCAKE_UBDIAG_LAYER=""
+    local MOONCAKE_UBDIAG_CLI_PATH=""
+    local MOONCAKE_UBDIAG_LIBRARY_PATH=""
+    local MOONCAKE_UBDIAG_CONFIG_PATH=""
+
+    if [ -f "${UBDIAG_RPM_MANIFEST}" ]; then
+        echo "Reading UbDiag RPM manifest: ${UBDIAG_RPM_MANIFEST}"
+        . "${UBDIAG_RPM_MANIFEST}"
+    fi
+
+    if { [ -z "${MOONCAKE_UBDIAG_LAYER}" ] || [ "${MOONCAKE_UBDIAG_LAYER}" = "submodule" ]; } && [ -d "${UBDIAG_BUILD_DIR}" ]; then
+        echo "Copying vendored UbDiag CLI and SDK runtime library..."
+
+        if [ -f "${UBDIAG_BUILD_DIR}/src/cli/ubdiag" ]; then
+            cp "${UBDIAG_BUILD_DIR}/src/cli/ubdiag" rpmbuild/BUILDROOT/${PACKAGE_NAME}-${PACKAGE_VERSION}-${PACKAGE_RELEASE}.${PLATFORM}/usr/bin/
+            chmod 755 rpmbuild/BUILDROOT/${PACKAGE_NAME}-${PACKAGE_VERSION}-${PACKAGE_RELEASE}.${PLATFORM}/usr/bin/ubdiag
+            UBDIAG_RPM_FILES="${UBDIAG_RPM_FILES}
+/usr/bin/ubdiag"
+        else
+            echo "Error: vendored UbDiag build found, but ${UBDIAG_BUILD_DIR}/src/cli/ubdiag is missing"
+            return 1
+        fi
+
+        if compgen -G "${UBDIAG_BUILD_DIR}/src/sdk/libubdiag.so*" >/dev/null; then
+            for ubdiag_lib in "${UBDIAG_BUILD_DIR}"/src/sdk/libubdiag.so*; do
+                cp "${ubdiag_lib}" rpmbuild/BUILDROOT/${PACKAGE_NAME}-${PACKAGE_VERSION}-${PACKAGE_RELEASE}.${PLATFORM}/usr/${LIB_DIR}/
+            done
+            chmod 755 rpmbuild/BUILDROOT/${PACKAGE_NAME}-${PACKAGE_VERSION}-${PACKAGE_RELEASE}.${PLATFORM}/usr/${LIB_DIR}/libubdiag.so* 2>/dev/null || true
+            UBDIAG_RPM_FILES="${UBDIAG_RPM_FILES}
+/usr/${LIB_DIR}/libubdiag.so*"
+        elif [ -f "${UBDIAG_BUILD_DIR}/src/sdk/libubdiag.a" ]; then
+            cp "${UBDIAG_BUILD_DIR}/src/sdk/libubdiag.a" rpmbuild/BUILDROOT/${PACKAGE_NAME}-${PACKAGE_VERSION}-${PACKAGE_RELEASE}.${PLATFORM}/usr/${LIB_DIR}/
+            UBDIAG_RPM_FILES="${UBDIAG_RPM_FILES}
+/usr/${LIB_DIR}/libubdiag.a"
+        else
+            echo "Error: vendored UbDiag build found, but libubdiag was not built under ${UBDIAG_BUILD_DIR}/src/sdk"
+            return 1
+        fi
+
+        if [ -f extern/ubdiag/config/ubdiag.conf.example ]; then
+            cp extern/ubdiag/config/ubdiag.conf.example rpmbuild/BUILDROOT/${PACKAGE_NAME}-${PACKAGE_VERSION}-${PACKAGE_RELEASE}.${PLATFORM}/etc/ubdiag/ubdiag.conf
+            UBDIAG_RPM_FILES="${UBDIAG_RPM_FILES}
+%config(noreplace) /etc/ubdiag/ubdiag.conf"
+        else
+            echo "Warning: extern/ubdiag/config/ubdiag.conf.example not found, skipping UbDiag config..."
+        fi
+    elif [ "${MOONCAKE_UBDIAG_LAYER}" = "system" ]; then
+        echo "Copying system UbDiag CLI and SDK runtime library selected by Layer 2..."
+
+        if [ -z "${MOONCAKE_UBDIAG_CLI_PATH}" ] || [ ! -f "${MOONCAKE_UBDIAG_CLI_PATH}" ]; then
+            echo "Error: Layer 2 selected system UbDiag, but ubdiag CLI was not found"
+            echo "       Expected CLI path from manifest: ${MOONCAKE_UBDIAG_CLI_PATH}"
+            return 1
+        fi
+
+        cp "${MOONCAKE_UBDIAG_CLI_PATH}" rpmbuild/BUILDROOT/${PACKAGE_NAME}-${PACKAGE_VERSION}-${PACKAGE_RELEASE}.${PLATFORM}/usr/bin/ubdiag
+        chmod 755 rpmbuild/BUILDROOT/${PACKAGE_NAME}-${PACKAGE_VERSION}-${PACKAGE_RELEASE}.${PLATFORM}/usr/bin/ubdiag
+        UBDIAG_RPM_FILES="${UBDIAG_RPM_FILES}
+/usr/bin/ubdiag"
+
+        local UBDIAG_SYSTEM_LIB_DIR=""
+        if [ -n "${MOONCAKE_UBDIAG_LIBRARY_PATH}" ] && [ -e "${MOONCAKE_UBDIAG_LIBRARY_PATH}" ]; then
+            UBDIAG_SYSTEM_LIB_DIR="$(dirname "${MOONCAKE_UBDIAG_LIBRARY_PATH}")"
+        fi
+        if [ -z "${UBDIAG_SYSTEM_LIB_DIR}" ] || ! compgen -G "${UBDIAG_SYSTEM_LIB_DIR}/libubdiag.so*" >/dev/null; then
+            for ubdiag_lib_dir in /usr/lib64 /usr/local/lib64 /usr/lib /usr/local/lib; do
+                if compgen -G "${ubdiag_lib_dir}/libubdiag.so*" >/dev/null; then
+                    UBDIAG_SYSTEM_LIB_DIR="${ubdiag_lib_dir}"
+                    break
+                fi
+            done
+        fi
+        if [ -z "${UBDIAG_SYSTEM_LIB_DIR}" ] || ! compgen -G "${UBDIAG_SYSTEM_LIB_DIR}/libubdiag.so*" >/dev/null; then
+            echo "Error: Layer 2 selected system UbDiag, but libubdiag.so* was not found"
+            echo "       Expected library path from manifest: ${MOONCAKE_UBDIAG_LIBRARY_PATH}"
+            return 1
+        fi
+
+        for ubdiag_lib in "${UBDIAG_SYSTEM_LIB_DIR}"/libubdiag.so*; do
+            cp -P "${ubdiag_lib}" rpmbuild/BUILDROOT/${PACKAGE_NAME}-${PACKAGE_VERSION}-${PACKAGE_RELEASE}.${PLATFORM}/usr/${LIB_DIR}/
+        done
+        chmod 755 rpmbuild/BUILDROOT/${PACKAGE_NAME}-${PACKAGE_VERSION}-${PACKAGE_RELEASE}.${PLATFORM}/usr/${LIB_DIR}/libubdiag.so* 2>/dev/null || true
+        UBDIAG_RPM_FILES="${UBDIAG_RPM_FILES}
+/usr/${LIB_DIR}/libubdiag.so*"
+
+        if [ -n "${MOONCAKE_UBDIAG_CONFIG_PATH}" ] && [ -f "${MOONCAKE_UBDIAG_CONFIG_PATH}" ]; then
+            cp "${MOONCAKE_UBDIAG_CONFIG_PATH}" rpmbuild/BUILDROOT/${PACKAGE_NAME}-${PACKAGE_VERSION}-${PACKAGE_RELEASE}.${PLATFORM}/etc/ubdiag/ubdiag.conf
+            UBDIAG_RPM_FILES="${UBDIAG_RPM_FILES}
+%config(noreplace) /etc/ubdiag/ubdiag.conf"
+        else
+            echo "Warning: Layer 2 system UbDiag config not found, skipping UbDiag config..."
+        fi
+    else
+        echo "UbDiag layer is '${MOONCAKE_UBDIAG_LAYER:-unknown}', skipping UbDiag CLI packaging..."
+    fi
     
     # -------------------------------------------------------------------------
     # Copy header files (only core headers for real_client and dummy_client)
@@ -324,6 +437,7 @@ ${PACKAGE_DESCRIPTION}
 /usr/${LIB_DIR}/libetcd_wrapper.so
 /usr/${LIB_DIR}/libmooncake_engine.so
 /usr/${LIB_DIR}/libmooncake_store_python.so
+${UBDIAG_RPM_FILES}
 /usr/include/mooncake/*.h
 /usr/include/mooncake/*.hpp
 /etc/mooncake/master.yaml
@@ -352,16 +466,16 @@ EOF
     fi
     
     # Create platform-specific output directory
-    mkdir -p ${OUTPUT_DIR}/${PLATFORM}
+    mkdir -p ${OUTPUT_DIR_ABS}/${PLATFORM}
     
     # Build the RPM
     rpmbuild -bb \
         --define "_topdir $(pwd)/rpmbuild" \
-        --define "_rpmdir $(pwd)/${OUTPUT_DIR}" \
+        --define "_rpmdir ${OUTPUT_DIR_ABS}" \
         rpmbuild/SPECS/${PACKAGE_NAME}-${PLATFORM}.spec
     
     # Move RPM to platform-specific directory
-    mv ${OUTPUT_DIR}/${PLATFORM}/*.rpm ${OUTPUT_DIR}/ 2>/dev/null || true
+    mv ${OUTPUT_DIR_ABS}/${PLATFORM}/*.rpm ${OUTPUT_DIR_ABS}/ 2>/dev/null || true
     
     # Cleanup BUILDROOT for next platform
     rm -rf rpmbuild/BUILDROOT/
@@ -395,7 +509,7 @@ fi
 # List created RPM files
 echo "RPM packages built successfully!"
 echo "Created RPM files:"
-ls -la ${OUTPUT_DIR}/*.rpm 2>/dev/null || echo "No RPM files created"
+ls -la ${OUTPUT_DIR_ABS}/*.rpm 2>/dev/null || echo "No RPM files created"
 
 # Cleanup
-rm -rf rpmbuild/
\ No newline at end of file
+rm -rf rpmbuild/