--- ../tests/src/workspace/convention.cpp	2026-09-25 14:56:49.048513990 +0300
+++ ../tests/src/workspace/convention.cpp	2026-09-25 15:03:18.117427186 +0300
@@ -15,6 +15,16 @@
 using namespace lito_test;
 using PathBuf = rstd::path::PathBuf;
 
+auto workspace_pmacro_source_options(ref<rstd::path::Path> support)
+    -> lito::source::SourceResolutionOptions {
+    auto options = lito::source::SourceResolutionOptions {};
+    options.sources.builtin_packages.push(lito::source::BuiltinPackageSourceEntry {
+        .id     = "pmacro"_Str,
+        .source = lito::source::BuiltinPackageSource::Path(PathBuf::from(support)),
+    });
+    return options;
+}
+
 auto associated_workspace_tree() -> lito::source::SourceTreeResult<lito::source::SourceTree> {
     constexpr ProjectFile files[] = {
         { "lito.toml"_str, R"([workspace]
@@ -445,8 +455,24 @@
     ASSERT_TRUE(tree.is_ok());
     auto project = materialize("associated-test-workspace"_str, *tree);
     ASSERT_TRUE(project.is_ok());
+
+    constexpr ProjectFile support_files[] = {
+        { "lito.toml"_str, R"([package]
+name = "pmacro"
+version = "0.1.0"
+
+[plugin]
+module = "pmacro"
+sources = ["lib.cppm"]
+)"_str },
+        { "lib.cppm"_str, "export module pmacro;\n"_str },
+    };
+    auto support = materialize("associated-test-workspace-pmacro"_str, support_files);
+    ASSERT_TRUE(support.is_ok());
+
     auto directory = project->root.clone();
-    auto graph     = lito::package::resolve_package_graph(directory.as_path());
+    auto graph = lito::package::resolve_package_graph(
+        directory.as_path(), workspace_pmacro_source_options(support->root.as_path()));
     ASSERT_TRUE(graph.is_ok());
     ASSERT_EQ(graph->roots.len(), usize(4));
     auto library = project_root_role(*graph, "fixture-conventional-workspace-library"_str);
@@ -464,7 +490,8 @@
 
     auto production = lito::package::resolve_package_selection(
         lito::package::PackageSelection { .root = directory.clone() },
-        lito::package::PackageSelectionPurpose::Production);
+        lito::package::PackageSelectionPurpose::Production,
+        workspace_pmacro_source_options(support->root.as_path()));
     ASSERT_TRUE(production.is_ok());
     ASSERT_EQ(production->selected_root_names.len(), usize(1));
     EXPECT_EQ(production->selected_root_names[usize {}].as_str(),
@@ -472,7 +499,8 @@
 
     auto tests = lito::package::resolve_package_selection(
         lito::package::PackageSelection { .root = directory.clone() },
-        lito::package::PackageSelectionPurpose::Test);
+        lito::package::PackageSelectionPurpose::Test,
+        workspace_pmacro_source_options(support->root.as_path()));
     ASSERT_TRUE(tests.is_ok());
     EXPECT_EQ(tests->selected_root_names.len(), usize(2));
     EXPECT_TRUE(