Index: lib/Comms/CMakeLists.txt
===================================================================
diff -u -refc0e8ccb0ee99f25834eb5a19dee1cf2e50c532 -r4dccc470aedf6f68a0ad73c1101f8a96188cbdb1
--- lib/Comms/CMakeLists.txt	(.../CMakeLists.txt)	(revision efc0e8ccb0ee99f25834eb5a19dee1cf2e50c532)
+++ lib/Comms/CMakeLists.txt	(.../CMakeLists.txt)	(revision 4dccc470aedf6f68a0ad73c1101f8a96188cbdb1)
@@ -47,11 +47,10 @@
     PUBLIC_HEADER "${INCLUDES}"
     ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/lib"
     LIBRARY_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/lib"
-    ADDITIONAL_CLEAN_FILES " \
-        ${CMAKE_CURRENT_SOURCE_DIR}/bin; \
-        ${CMAKE_CURRENT_SOURCE_DIR}/lib; \
-        ${CMAKE_CURRENT_SOURCE_DIR}/cmake \
-    "
+    ADDITIONAL_CLEAN_FILES
+        "${CMAKE_CURRENT_SOURCE_DIR}/bin"
+        "${CMAKE_CURRENT_SOURCE_DIR}/lib"
+        "${CMAKE_CURRENT_SOURCE_DIR}/cmake"
 )
 
 target_link_libraries(${PROJECT_NAME} PUBLIC
Index: lib/Comms/Comms.pro
===================================================================
diff -u -refc0e8ccb0ee99f25834eb5a19dee1cf2e50c532 -r4dccc470aedf6f68a0ad73c1101f8a96188cbdb1
--- lib/Comms/Comms.pro	(.../Comms.pro)	(revision efc0e8ccb0ee99f25834eb5a19dee1cf2e50c532)
+++ lib/Comms/Comms.pro	(.../Comms.pro)	(revision 4dccc470aedf6f68a0ad73c1101f8a96188cbdb1)
@@ -39,10 +39,13 @@
 
 INCLUDEPATH += $$PWD/include
 
-# MessageSpool uses the SQLite C API directly (see docs/SDD/AgentMigrationPlan.md
-# section 5.5). Requires libsqlite3-dev at build time.
 LIBS += -lsqlite3
 
+# qmake only removes the shared objects on distclean.
+# The following ensures that they are removed on clean, too.
+# It also ensures that all versioned symlinks (*.so.1, *.so.1.0, etc) are removed.
+QMAKE_CLEAN += $$DESTDIR/libComms.so*
+
 isEmpty(PREFIX): PREFIX = $$PWD/../../install
 
 target.path             = $$PREFIX/lib
Index: lib/MsgUtils/CMakeLists.txt
===================================================================
diff -u -ra5781739bcbe58c754aff8861561495624bc5b67 -r4dccc470aedf6f68a0ad73c1101f8a96188cbdb1
--- lib/MsgUtils/CMakeLists.txt	(.../CMakeLists.txt)	(revision a5781739bcbe58c754aff8861561495624bc5b67)
+++ lib/MsgUtils/CMakeLists.txt	(.../CMakeLists.txt)	(revision 4dccc470aedf6f68a0ad73c1101f8a96188cbdb1)
@@ -76,13 +76,12 @@
     PUBLIC_HEADER "${INCLUDES}"
     ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/lib"
     LIBRARY_OUTPUT_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/lib"
-    ADDITIONAL_CLEAN_FILES " \
-        ${CMAKE_CURRENT_SOURCE_DIR}/bin; \
-        ${CMAKE_CURRENT_SOURCE_DIR}/lib; \
-        ${CMAKE_CURRENT_SOURCE_DIR}/cmake; \
-        ${GENERATED_INCLUDES}; \
-        ${GENERATED_SRCS} \
-    "
+    ADDITIONAL_CLEAN_FILES
+        "${CMAKE_CURRENT_SOURCE_DIR}/bin"
+        "${CMAKE_CURRENT_SOURCE_DIR}/lib"
+        "${CMAKE_CURRENT_SOURCE_DIR}/cmake"
+        ${GENERATED_INCLUDES}
+        ${GENERATED_SRCS}
 )
 
 target_link_libraries(${PROJECT_NAME} PUBLIC
Index: lib/MsgUtils/MsgUtils.pro
===================================================================
diff -u -ra5781739bcbe58c754aff8861561495624bc5b67 -r4dccc470aedf6f68a0ad73c1101f8a96188cbdb1
--- lib/MsgUtils/MsgUtils.pro	(.../MsgUtils.pro)	(revision a5781739bcbe58c754aff8861561495624bc5b67)
+++ lib/MsgUtils/MsgUtils.pro	(.../MsgUtils.pro)	(revision 4dccc470aedf6f68a0ad73c1101f8a96188cbdb1)
@@ -118,20 +118,15 @@
 HEADERS += $$GENERATED_INCLUDES
 SOURCES += $$GENERATED_SRCS
 
-# Create the dependencies between the object files and generated files so generated files
-# are made before trying to compile them into objects. 
-protoutils_obj.target   = LeahiMsgProtoUtils.o
-protoutils_obj.depends  = $$GEN_INCLUDE_DIR/LeahiMsgDefs.pb.h
-QMAKE_EXTRA_TARGETS    += protoutils_obj
+# Ensure the generated headers are dependencies of the object files that need them
+# and are created first.
+generated_headers_first.target  = $(OBJECTS)
+generated_headers_first.depends = \
+    $$GEN_INCLUDE_DIR/LeahiMsgDefs.h \
+    $$GEN_INCLUDE_DIR/LeahiMsgDefs.pb.h \
+    $$GEN_INCLUDE_DIR/LeahiMsgProtoUtils.h
+QMAKE_EXTRA_TARGETS    += generated_headers_first
 
-msgdefs_obj.target      = LeahiMsgDefs.o
-msgdefs_obj.depends     = $$GEN_INCLUDE_DIR/LeahiMsgDefs.h
-QMAKE_EXTRA_TARGETS    += msgdefs_obj
-
-pb_obj.target           = LeahiMsgDefs.pb.o
-pb_obj.depends          = $$GEN_INCLUDE_DIR/LeahiMsgDefs.pb.h
-QMAKE_EXTRA_TARGETS    += pb_obj
-
 INCLUDEPATH += $$PWD/include
 
 LIBS += -lprotobuf
@@ -158,6 +153,9 @@
 export_pri.files    = $$PWD/MsgUtils.pri
 INSTALLS           += export_pri
 
+# qmake only removes the shared objects on distclean, so remove them on clean too
+QMAKE_CLEAN += $$DESTDIR/libMsgUtils.so*
+
 QMAKE_CLEAN += \
     $$GEN_INCLUDE_DIR/LeahiMsgDefs.h \
     $$GEN_INCLUDE_DIR/LeahiMsgDefs.pb.h \
Index: lib/MsgUtils/cmake/MsgUtils.cmake
===================================================================
diff -u -r64243101dff61b5c1a40b96ef33080236999acf6 -r4dccc470aedf6f68a0ad73c1101f8a96188cbdb1
--- lib/MsgUtils/cmake/MsgUtils.cmake	(.../MsgUtils.cmake)	(revision 64243101dff61b5c1a40b96ef33080236999acf6)
+++ lib/MsgUtils/cmake/MsgUtils.cmake	(.../MsgUtils.cmake)	(revision 4dccc470aedf6f68a0ad73c1101f8a96188cbdb1)
@@ -93,6 +93,14 @@
     )
 
     add_custom_target(${_target_name} DEPENDS ${_output_ini})
+
+    # CMake adds every custom-command OUTPUT to the clean target. Unlike the other
+    # generated files, this INI is persistent, so a clean must not delete it.
+    # CMake offers no per-output exemption, so the directory-scoped property is required,
+    # but a side effect is that the calling directory must not rely on clean removing other
+    # custom outputs in this directory. It is ok for now since the _output_ini is the only
+    # file in the directory, but may need to be addressed later if more files are added.
+    set_directory_properties(PROPERTIES CLEAN_NO_CUSTOM TRUE)
 endfunction()
 
 #   \brief  This function adds a custom command to generate a Protobuf file from inputted message conf files
Index: lib/MsgUtils/codegen.pri
===================================================================
diff -u -rb915ccc1a72fcca21908c35140af7ac7df1f1f37 -r4dccc470aedf6f68a0ad73c1101f8a96188cbdb1
--- lib/MsgUtils/codegen.pri	(.../codegen.pri)	(revision b915ccc1a72fcca21908c35140af7ac7df1f1f37)
+++ lib/MsgUtils/codegen.pri	(.../codegen.pri)	(revision 4dccc470aedf6f68a0ad73c1101f8a96188cbdb1)
@@ -2,8 +2,8 @@
 # Included by the components that generate code (e.g. MsgUtils and CloudConnect).
 #
 # qmake evaluates system() at qmake time, while QMAKE_EXTRA_COMPILERS /
-# QMAKE_EXTRA_TARGETS run at make time. The venv is created here (once, shared);
-# the generators are wired as make-time rules in the including .pro so they
+# QMAKE_EXTRA_TARGETS run at make time. The venv is created here once and shared.
+# The generators are wired as make-time rules in the including .pro so they
 # re-run on input change.
 
 PROJECT_ROOT = $$clean_path($$PWD/../..)
@@ -18,13 +18,42 @@
 PROJECT_PYTHON   = $$PROJECT_VENV_DIR/bin/python
 
 # Create the venv, then editable-install the msgutils package so the generator
-# scripts can `import msgutils`. Runs once per qmake invocation; pip is a skipped
-# when already satisfied.
+# scripts can `import msgutils`.
+#
+# A missing python3-venv reports nothing here and later becomes a generator rule
+# failing to find an interpreter. This checks and reports here if it is missing.
 !exists($$PROJECT_PYTHON) {
     message("Creating project Python venv at $$PROJECT_VENV_DIR")
-    system(python3 -m venv $$shell_quote($$PROJECT_VENV_DIR))
+
+    !system(python3 -m venv $$shell_quote($$PROJECT_VENV_DIR)) {
+        # $${} braces: qmake allows '.' in a variable name, so "$$VAR." reads as a
+        # variable named "VAR." and expands to nothing.
+        error("Could not create the Python venv at $${PROJECT_VENV_DIR}. On Debian/Ubuntu this usually means the venv module is missing: sudo apt install python3-venv")
+    }
+
+    # venv can exit 0 and still leave no interpreter (interrupted, disk full).
+    !exists($$PROJECT_PYTHON) {
+        error("The venv at $${PROJECT_VENV_DIR} was created but has no interpreter at $${PROJECT_PYTHON}. Remove the directory and re-run qmake.")
+    }
 }
-system($$shell_quote($$PROJECT_PYTHON) -m pip install --upgrade pip --quiet)
-system($$shell_quote($$PROJECT_PYTHON) -m pip install -e $$shell_quote($$MSGUTILS_SCRIPTS_DIR) --quiet)
 
+# Allow a machine with a working venv and no network can still build.
+!system($$shell_quote($$PROJECT_PYTHON) -m pip install --upgrade pip --quiet) {
+    warning("Could not upgrade pip in $${PROJECT_VENV_DIR}; continuing with the installed version.")
+}
+
+# The generators import msgutils, but a failed reinstall is survivable when the venv
+# already has it.
+!system($$shell_quote($$PROJECT_PYTHON) -m pip install -e $$shell_quote($$MSGUTILS_SCRIPTS_DIR) --quiet) {
+    !system($$shell_quote($$PROJECT_PYTHON) -c $$shell_quote(import msgutils)) {
+        error("Could not install msgutils from $${MSGUTILS_SCRIPTS_DIR} into $${PROJECT_VENV_DIR}, and it is not importable. The code generators cannot run.")
+    }
+    warning("Could not reinstall msgutils from $${MSGUTILS_SCRIPTS_DIR}; continuing with the copy already in the venv.")
+}
+
 PROTOC = protoc
+# Missing protoc reports nothing here and later becomes a generator rule failing with "command not found".
+# This checks and reports here if it is missing.
+!system($$PROTOC --version > /dev/null 2>&1) {
+    error("Could not run '$${PROTOC}'. On Debian/Ubuntu install it with: sudo apt install protobuf-compiler")
+}