Index: CMakeLists.txt
===================================================================
diff -u -rac303b902c681a25ff0d910dd56ab309669e381f -r6cdf791210cfa0d96514094d33510e639f9bc0b6
--- CMakeLists.txt	(.../CMakeLists.txt)	(revision ac303b902c681a25ff0d910dd56ab309669e381f)
+++ CMakeLists.txt	(.../CMakeLists.txt)	(revision 6cdf791210cfa0d96514094d33510e639f9bc0b6)
@@ -6,6 +6,7 @@
 )
 
 include(cmake/Debug.cmake)
+include(cmake/PythonVenv.cmake)
 
 set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
Index: cmake/PythonVenv.cmake
===================================================================
diff -u
--- cmake/PythonVenv.cmake	(revision 0)
+++ cmake/PythonVenv.cmake	(revision 6cdf791210cfa0d96514094d33510e639f9bc0b6)
@@ -0,0 +1,113 @@
+# PythonVenv.cmake — project-wide Python venv shared by every component that
+# ships Python tooling (currently MsgUtils; LogReader will join later).
+#
+# Why a venv at all: PEP 668 distros (Debian/Ubuntu with Python 3.11+, etc.)
+# forbid `pip install` into the system or user site-packages. The venv lets
+# editable installs work without `--break-system-packages` and without
+# polluting the developer's machine.
+#
+# Why project-level (and not per-component): more than one component needs a
+# Python interpreter to install into; pointing each at the same venv keeps
+# every installed package mutually importable, avoids duplicate venv setup
+# code in every CMakeLists.txt, and makes "where do my Python deps live"
+# answerable in one place.
+#
+# Usage:
+#   include(cmake/PythonVenv.cmake)            # creates ${PROJECT_PYTHON}
+#   register_python_package(<absolute_dir>)    # pip install -e the given pyproject
+#
+# Re-installs only when the package's pyproject.toml changes — keyed via a
+# build-tree stamp file, so reconfigures stay fast.
+
+if(DEFINED PROJECT_PYTHON_INCLUDED)
+    return()
+endif()
+set(PROJECT_PYTHON_INCLUDED TRUE)
+
+find_package(Python3 REQUIRED COMPONENTS Interpreter)
+
+set(PROJECT_VENV_DIR ${CMAKE_BINARY_DIR}/.venv CACHE INTERNAL "Project Python venv root")
+set(PROJECT_PYTHON   ${PROJECT_VENV_DIR}/bin/python CACHE INTERNAL "Project venv python interpreter")
+
+# Probe pip inside the venv. A half-created venv (missing python3-venv on the
+# host) can have python but no pip — we want to catch that and report it
+# clearly rather than failing on the first `pip install`.
+execute_process(
+    COMMAND ${PROJECT_PYTHON} -m pip --version
+    RESULT_VARIABLE _venv_pip_ok
+    OUTPUT_QUIET
+    ERROR_QUIET
+)
+if(NOT _venv_pip_ok EQUAL 0)
+    message(STATUS "Creating project Python venv at ${PROJECT_VENV_DIR}")
+    file(REMOVE_RECURSE ${PROJECT_VENV_DIR})
+    execute_process(
+        COMMAND ${Python3_EXECUTABLE} -m venv ${PROJECT_VENV_DIR}
+        RESULT_VARIABLE _venv_result
+        OUTPUT_VARIABLE _venv_output
+        ERROR_VARIABLE _venv_output
+    )
+    if(NOT _venv_result EQUAL 0 OR NOT EXISTS ${PROJECT_PYTHON})
+        message(FATAL_ERROR
+            "Failed to create venv at ${PROJECT_VENV_DIR}.\n"
+            "Install the venv module (e.g. 'sudo apt install python3-venv' or 'python3-full' on Debian/Ubuntu, "
+            "matching your Python version).\n"
+            "Output:\n${_venv_output}")
+    endif()
+    execute_process(
+        COMMAND ${PROJECT_PYTHON} -m pip --version
+        RESULT_VARIABLE _venv_pip_ok
+        OUTPUT_QUIET
+        ERROR_QUIET
+    )
+    if(NOT _venv_pip_ok EQUAL 0)
+        message(FATAL_ERROR
+            "Venv at ${PROJECT_VENV_DIR} was created but pip is not available inside it. "
+            "Install the matching python3-venv package and reconfigure.")
+    endif()
+endif()
+
+# Editable installs via pyproject.toml require pip >= 21.3. Upgrade once per
+# configure; cheap when already up-to-date.
+execute_process(
+    COMMAND ${PROJECT_PYTHON} -m pip install --upgrade pip --quiet
+    RESULT_VARIABLE _pip_upgrade_result
+)
+if(NOT _pip_upgrade_result EQUAL 0)
+    message(FATAL_ERROR "Failed to upgrade pip in project venv (pip returned ${_pip_upgrade_result})")
+endif()
+
+# register_python_package(<absolute_dir>)
+#
+# Installs the pyproject at <absolute_dir> editable into the project venv.
+# Re-runs only when <absolute_dir>/pyproject.toml's mtime moves past a stamp
+# file in the build tree, so reconfiguring on an unchanged tree is a no-op.
+# Stamps are namespaced by the leaf directory name so two pyprojects in
+# different directories don't clobber each other.
+function(register_python_package _pkg_dir)
+    if(NOT IS_ABSOLUTE "${_pkg_dir}")
+        message(FATAL_ERROR "register_python_package: path must be absolute: ${_pkg_dir}")
+    endif()
+    set(_pyproject "${_pkg_dir}/pyproject.toml")
+    if(NOT EXISTS "${_pyproject}")
+        message(FATAL_ERROR "register_python_package: no pyproject.toml at ${_pkg_dir}")
+    endif()
+
+    get_filename_component(_leaf "${_pkg_dir}" NAME)
+    set(_stamp "${CMAKE_BINARY_DIR}/python-venv-stamps/${_leaf}.installed")
+
+    # Compare stamp mtime to the pyproject's. IS_NEWER_THAN treats a missing
+    # stamp as "older", so first configure always installs.
+    if("${_pyproject}" IS_NEWER_THAN "${_stamp}")
+        message(STATUS "Installing Python package ${_leaf} into project venv")
+        execute_process(
+            COMMAND ${PROJECT_PYTHON} -m pip install -e ${_pkg_dir} --quiet
+            RESULT_VARIABLE _pip_result
+        )
+        if(NOT _pip_result EQUAL 0)
+            message(FATAL_ERROR "Failed to install ${_leaf} into project venv (pip returned ${_pip_result})")
+        endif()
+        file(MAKE_DIRECTORY "${CMAKE_BINARY_DIR}/python-venv-stamps")
+        file(TOUCH "${_stamp}")
+    endif()
+endfunction()
Index: lib/MsgUtils/CMakeLists.txt
===================================================================
diff -u -rbde1243eb2ff6af2868f6c6ad0cb4f5760aaf68b -r6cdf791210cfa0d96514094d33510e639f9bc0b6
--- lib/MsgUtils/CMakeLists.txt	(.../CMakeLists.txt)	(revision bde1243eb2ff6af2868f6c6ad0cb4f5760aaf68b)
+++ lib/MsgUtils/CMakeLists.txt	(.../CMakeLists.txt)	(revision 6cdf791210cfa0d96514094d33510e639f9bc0b6)
@@ -11,74 +11,18 @@
 
 find_package(Protobuf REQUIRED)
 find_package(absl REQUIRED)
-find_package(Python3 REQUIRED COMPONENTS Interpreter)
 find_package(QT NAMES Qt6 Qt5 REQUIRED COMPONENTS Core)
 find_package(Qt${QT_VERSION_MAJOR} REQUIRED COMPONENTS Core Network SerialBus)
 
 set(MSGUTILS_SCRIPTS_DIR ${CMAKE_SOURCE_DIR}/scripts/MsgUtils)
 
-# Create a build-local venv so pip install works on distros that enforce PEP 668
-# (Debian/Ubuntu with Python 3.11+, etc.) without polluting system or user site-packages.
-set(MSGUTILS_VENV_DIR ${CMAKE_CURRENT_BINARY_DIR}/msgutils-venv)
-set(MSGUTILS_PYTHON ${MSGUTILS_VENV_DIR}/bin/python)
-# Probe pip inside the venv — a half-created venv missing python3-venv has python but no pip.
-execute_process(
-    COMMAND ${MSGUTILS_PYTHON} -m pip --version
-    RESULT_VARIABLE _venv_pip_ok
-    OUTPUT_QUIET
-    ERROR_QUIET
-)
-if(NOT _venv_pip_ok EQUAL 0)
-    message(STATUS "Creating msgutils Python venv at ${MSGUTILS_VENV_DIR}")
-    file(REMOVE_RECURSE ${MSGUTILS_VENV_DIR})
-    execute_process(
-        COMMAND ${Python3_EXECUTABLE} -m venv ${MSGUTILS_VENV_DIR}
-        RESULT_VARIABLE _venv_result
-        OUTPUT_VARIABLE _venv_output
-        ERROR_VARIABLE _venv_output
-    )
-    if(NOT _venv_result EQUAL 0 OR NOT EXISTS ${MSGUTILS_PYTHON})
-        message(FATAL_ERROR
-            "Failed to create venv at ${MSGUTILS_VENV_DIR}.\n"
-            "Install the venv module (e.g. 'sudo apt install python3-venv' or 'python3-full' on Debian/Ubuntu, "
-            "matching your Python version).\n"
-            "Output:\n${_venv_output}")
-    endif()
-    # Verify pip is actually usable in the new venv.
-    execute_process(
-        COMMAND ${MSGUTILS_PYTHON} -m pip --version
-        RESULT_VARIABLE _venv_pip_ok
-        OUTPUT_QUIET
-        ERROR_QUIET
-    )
-    if(NOT _venv_pip_ok EQUAL 0)
-        message(FATAL_ERROR
-            "Venv at ${MSGUTILS_VENV_DIR} was created but pip is not available inside it. "
-            "Install the matching python3-venv package and reconfigure.")
-    endif()
-endif()
-
+# The project-wide venv ({CMAKE_BINARY_DIR}/.venv) is set up by
+# cmake/PythonVenv.cmake at the top level; ${PROJECT_PYTHON} resolves to its
+# interpreter. We install the msgutils package editable so the generator
+# scripts below can `import msgutils` regardless of how they're invoked.
 include(cmake/MsgUtils.cmake)
+register_python_package(${MSGUTILS_SCRIPTS_DIR})
 
-# Upgrade pip to ensure pyproject.toml-based editable installs are supported (requires pip >= 21.3).
-execute_process(
-    COMMAND ${MSGUTILS_PYTHON} -m pip install --upgrade pip --quiet
-    RESULT_VARIABLE _pip_upgrade_result
-)
-if(NOT _pip_upgrade_result EQUAL 0)
-    message(FATAL_ERROR "Failed to upgrade pip in msgutils venv (pip returned ${_pip_upgrade_result})")
-endif()
-
-# install the Python package in editable mode so that the generated protobuf files can be imported by the Python scripts
-# without needing to be copied to the Python package directory
-execute_process(
-    COMMAND ${MSGUTILS_PYTHON} -m pip install -e ${MSGUTILS_SCRIPTS_DIR} --quiet
-    RESULT_VARIABLE _pip_result
-)
-if(NOT _pip_result EQUAL 0)
-    message(FATAL_ERROR "Failed to install msgutils Python package (pip returned ${_pip_result})")
-endif()
-
 # set(DENALI_MSG_CSV ${CMAKE_CURRENT_SOURCE_DIR}/../../data/FW_Messages_List.csv)
 set(LEAHI_MSG_CSV ${CMAKE_CURRENT_SOURCE_DIR}/../../data/Leahi_Staging_FW_Messages_List.csv)
 set(LEAHI_MSG_CONF ${CMAKE_CURRENT_SOURCE_DIR}/../../data/LeahiUnhandled.conf)
Index: lib/MsgUtils/cmake/MsgUtils.cmake
===================================================================
diff -u -r2c00c6e743844c9a71fa03ce5a5c436ef3836484 -r6cdf791210cfa0d96514094d33510e639f9bc0b6
--- lib/MsgUtils/cmake/MsgUtils.cmake	(.../MsgUtils.cmake)	(revision 2c00c6e743844c9a71fa03ce5a5c436ef3836484)
+++ lib/MsgUtils/cmake/MsgUtils.cmake	(.../MsgUtils.cmake)	(revision 6cdf791210cfa0d96514094d33510e639f9bc0b6)
@@ -37,7 +37,7 @@
             ${_header_path}
             ${_source_path}
         COMMAND
-            ${MSGUTILS_PYTHON} ${MSGUTILS_SCRIPTS_DIR}/GenerateMsgDefsCpp.py
+            ${PROJECT_PYTHON} ${MSGUTILS_SCRIPTS_DIR}/GenerateMsgDefsCpp.py
                 --namespace ${_namespace}
                 --header_dir ${_header_dir}
                 --source_dir ${_source_dir}
@@ -79,7 +79,7 @@
         OUTPUT
             ${_protobuf_abs_filename}
         COMMAND
-            ${MSGUTILS_PYTHON} ${MSGUTILS_SCRIPTS_DIR}/GenerateProtobuf.py
+            ${PROJECT_PYTHON} ${MSGUTILS_SCRIPTS_DIR}/GenerateProtobuf.py
                 --namespace ${_namespace}
                 --output_dir ${_output_path}
                 ${${_input_confs}}
@@ -128,7 +128,7 @@
             ${_header_path}
             ${_source_path}
         COMMAND
-            ${MSGUTILS_PYTHON} ${MSGUTILS_SCRIPTS_DIR}/GenerateMsgDefsCpp.py
+            ${PROJECT_PYTHON} ${MSGUTILS_SCRIPTS_DIR}/GenerateMsgDefsCpp.py
                 --namespace ${_namespace}
                 --header_dir ${_header_dir}
                 --source_dir ${_source_dir}
@@ -170,7 +170,7 @@
         OUTPUT
             ${_protobuf_abs_filename}
         COMMAND
-            ${MSGUTILS_PYTHON} ${MSGUTILS_SCRIPTS_DIR}/GenerateProtobuf.py
+            ${PROJECT_PYTHON} ${MSGUTILS_SCRIPTS_DIR}/GenerateProtobuf.py
                 --namespace ${_namespace}
                 --output_dir ${_output_path}
                 ${${_input_csvs}}