fix: isolate plugin CLI import side effects

reme/plugin_cli.py

@@ -127,7 +127,13 @@ def _installed_manifest(plugin: InstalledPlugin) -> PluginManifest:
         path = Path(distribution.locate_file(relative))
         if path.is_file():
             return parse_plugin_manifest(path.read_text(encoding="utf-8"), plugin_name=plugin.name)
-    return load_package_manifest(plugin.target, plugin_name=plugin.name)
+    # Editable installs may not expose package data through ``locate_file``.
+    # Importlib resources then has to import the package, whose ``__init__``
+    # may still contain legacy registration side effects.
+    from .components.component_registry import R
+
+    with R.preserve(allow_mutation=True):
+        return load_package_manifest(plugin.target, plugin_name=plugin.name)
 
 
 def _plugin_details(plugin: InstalledPlugin) -> dict:
@@ -233,6 +239,7 @@ def _validate_installed(name: str) -> list[str]:
 
 
 def _validate_local(path: Path) -> list[str]:
+    from .components.component_registry import R
     from .plugin import Backend, Plugin, _load_backend
 
     project_file = path if path.name == "pyproject.toml" else path / "pyproject.toml"
@@ -249,18 +256,21 @@ def _validate_local(path: Path) -> list[str]:
     plugins = []
     sys.path.insert(0, str(source_root.resolve()))
     try:
-        for name, package in entry_points.items():
-            if not isinstance(name, str) or not isinstance(package, str) or ":" in package:
-                raise ValueError("Local validation requires package-only manifest entry points")
-            manifest_path = source_root.joinpath(*package.split(".")).joinpath(PLUGIN_MANIFEST)
-            if not manifest_path.is_file():
-                raise FileNotFoundError(f"Plugin manifest not found: {manifest_path}")
-            manifest = parse_plugin_manifest(manifest_path.read_text(encoding="utf-8"), plugin_name=name)
-            backends = tuple(
-                Backend(backend_name, _load_backend(target, plugin_name=name))
-                for backend_name, target in manifest.backends.items()
-            )
-            plugins.append(Plugin(name=name, backends=backends, config=manifest.application_defaults))
+        # Match installed-plugin loading: imports may execute compatibility
+        # decorators, but they must not mutate the frozen built-in template.
+        with R.preserve(allow_mutation=True):
+            for name, package in entry_points.items():
+                if not isinstance(name, str) or not isinstance(package, str) or ":" in package:
+                    raise ValueError("Local validation requires package-only manifest entry points")
+                manifest_path = source_root.joinpath(*package.split(".")).joinpath(PLUGIN_MANIFEST)
+                if not manifest_path.is_file():
+                    raise FileNotFoundError(f"Plugin manifest not found: {manifest_path}")
+                manifest = parse_plugin_manifest(manifest_path.read_text(encoding="utf-8"), plugin_name=name)
+                backends = tuple(
+                    Backend(backend_name, _load_backend(target, plugin_name=name))
+                    for backend_name, target in manifest.backends.items()
+                )
+                plugins.append(Plugin(name=name, backends=backends, config=manifest.application_defaults))
         _validate_plugins(plugins)
     finally:
         sys.path.remove(str(source_root.resolve()))

tests/unit/test_plugin_cli.py

@@ -7,6 +7,8 @@ from types import SimpleNamespace
 
 from reme import plugin_cli as plugin_cli_module
 from reme import reme as reme_module
+from reme.components import R
+from reme.enumeration import ComponentEnum
 
 
 class _FakeDistribution:
@@ -94,6 +96,34 @@ def test_show_plugin_reads_manifest_without_importing_backends(monkeypatch, tmp_
     assert "auto_fin" in output
 
 
+def test_show_plugin_preserves_registry_when_editable_fallback_imports_package(monkeypatch, tmp_path, capsys):
+    package = tmp_path / "fallback_plugin"
+    package.mkdir()
+    (package / "__init__.py").write_text("from .backend import FallbackStep\n", encoding="utf-8")
+    (package / "backend.py").write_text(
+        "from reme.components import ComponentMixin, R\n"
+        "from reme.enumeration import ComponentEnum\n"
+        "@R.register('fallback_import_side_effect')\n"
+        "class FallbackStep(ComponentMixin):\n"
+        "    component_type = ComponentEnum.STEP\n",
+        encoding="utf-8",
+    )
+    (package / "plugin.yaml").write_text(
+        """backends:
+  fallback_step: fallback_plugin.backend:FallbackStep
+""",
+        encoding="utf-8",
+    )
+    entry = _FakeEntryPoint("fallback", "fallback_plugin", _FakeDistribution(tmp_path / "missing"))
+    monkeypatch.syspath_prepend(str(tmp_path))
+    monkeypatch.setattr(plugin_cli_module.metadata, "entry_points", lambda: _FakeEntryPoints([entry]))
+
+    assert plugin_cli_module.plugin_cli(["show", "fallback"]) == 0
+
+    assert "fallback_step" in capsys.readouterr().out
+    assert R.get(ComponentEnum.STEP, "fallback_import_side_effect") is None
+
+
 def test_install_uses_current_python_pip(monkeypatch, capsys):
     commands = []
     monkeypatch.setattr(plugin_cli_module, "_run_pip", lambda command: commands.append(command) or 0)
@@ -146,6 +176,39 @@ def test_validate_local_auto_fin_project():
     assert names == ["auto-fin"]
 
 
+def test_validate_local_preserves_registry_during_backend_imports(tmp_path):
+    package = tmp_path / "src" / "decorated_plugin"
+    package.mkdir(parents=True)
+    (tmp_path / "pyproject.toml").write_text(
+        "[project]\n"
+        "name = 'decorated-plugin'\n"
+        "version = '0.1.0'\n"
+        "[project.entry-points.'reme.plugins']\n"
+        "decorated = 'decorated_plugin'\n"
+        "[tool.setuptools.package-dir]\n"
+        "'' = 'src'\n",
+        encoding="utf-8",
+    )
+    (package / "__init__.py").write_text("", encoding="utf-8")
+    (package / "backend.py").write_text(
+        "from reme.components import ComponentMixin, R\n"
+        "from reme.enumeration import ComponentEnum\n"
+        "@R.register('local_import_side_effect')\n"
+        "class DecoratedStep(ComponentMixin):\n"
+        "    component_type = ComponentEnum.STEP\n",
+        encoding="utf-8",
+    )
+    (package / "plugin.yaml").write_text(
+        """backends:
+  decorated_step: decorated_plugin.backend:DecoratedStep
+""",
+        encoding="utf-8",
+    )
+
+    assert plugin_cli_module._validate_local(tmp_path) == ["decorated"]
+    assert R.get(ComponentEnum.STEP, "local_import_side_effect") is None
+
+
 def test_plugin_command_errors_are_clean(monkeypatch, capsys):
     monkeypatch.setattr(plugin_cli_module.metadata, "entry_points", _FakeEntryPoints)