Add known working config profile for reverting changes

tests/test_plugin_helper.py

@@ -861,6 +861,97 @@ sha256 = "{sha256_file(asset)}"
             self.assertIn("example", updated["plugins"])
             self.assertNotIn("example", updated["disabledPlugins"])
 
+    def test_save_and_restore_known_good_set(self) -> None:
+        from plugin_helper.operations import restore_known_good_set, save_known_good_set
+        from plugin_helper.state import load_known_good_state, save_installed_state
+
+        with tempfile.TemporaryDirectory() as tmp:
+            work = Path(tmp)
+            instance_root = work / "instances"
+            instance = instance_root / "1.40.8"
+            state = work / "state"
+            registry_dir = work / "registry"
+            locks_dir = work / "locks"
+            registry_dir.mkdir()
+            locks_dir.mkdir()
+            instance.mkdir(parents=True)
+            (instance / "Beat Saber_Data").mkdir()
+            (instance / "Plugins").mkdir()
+
+            plugins_state: dict[str, dict] = {}
+            registry_entries: list[str] = []
+            lock_entries: list[str] = []
+            for plugin_id, name, filename in (
+                ("alpha", "Alpha", "Alpha.dll"),
+                ("beta", "Beta", "Beta.dll"),
+                ("gamma", "Gamma", "Gamma.dll"),
+            ):
+                asset = plugin_downloads_dir(state, "1.40.8", plugin_id) / filename
+                asset.write_bytes(f"{plugin_id} dll".encode())
+                registry_entries.append(
+                    f"""
+[[plugins]]
+id = "{plugin_id}"
+name = "{name}"
+repo = "owner/{plugin_id}"
+asset_patterns = ["*.dll"]
+install_strategy = "dll-to-plugins"
+""".lstrip()
+                )
+                lock_entries.append(
+                    f"""
+[[plugins]]
+id = "{plugin_id}"
+repo = "owner/{plugin_id}"
+tag = "v1.0.0"
+asset = "{filename}"
+sha256 = "{sha256_file(asset)}"
+""".lstrip()
+                )
+                if plugin_id in ("alpha", "beta"):
+                    (instance / "Plugins" / filename).write_bytes(f"{plugin_id} dll".encode())
+                    plugins_state[plugin_id] = {
+                        "installedAt": "2026-06-14T17:18:40Z",
+                        "files": [{"path": f"Plugins/{filename}", "sha256": sha256_file(asset), "size": asset.stat().st_size}],
+                    }
+
+            (registry_dir / "plugins.toml").write_text("".join(registry_entries), encoding="utf-8")
+            (locks_dir / "1.40.8.lock.toml").write_text(
+                f"""
+beat_saber_version = "1.40.8"
+instance = "1.40.8"
+{"".join(lock_entries)}
+""".lstrip(),
+                encoding="utf-8",
+            )
+            save_installed_state(state, "1.40.8", {"instance": "1.40.8", "plugins": plugins_state, "disabledPlugins": {}})
+
+            known_good = save_known_good_set(instance="1.40.8", state_root=state)
+            self.assertEqual(known_good["pluginIds"], ["alpha", "beta"])
+            self.assertEqual(load_known_good_state(state, "1.40.8")["pluginIds"], ["alpha", "beta"])
+
+            # Simulate the user disabling alpha and a new mod pulling in gamma as a dependency.
+            disable_plugin("1.40.8", instance, state, "alpha", False)
+            with patch("plugin_helper.operations.repo_root", return_value=work):
+                enable_disabled_plugin(
+                    instance="1.40.8",
+                    instance_path=instance,
+                    state_root=state,
+                    plugin_id="gamma",
+                    repo=work,
+                )
+
+                result = restore_known_good_set(instance="1.40.8", instance_path=instance, state_root=state, repo=work)
+
+            self.assertEqual(result["disabled"], ["gamma"])
+            self.assertEqual(result["enabled"], ["alpha"])
+            self.assertEqual(result["disableErrors"], [])
+            self.assertEqual(result["enableErrors"], [])
+
+            updated = load_installed_state(state, "1.40.8")
+            self.assertEqual(set(updated["plugins"]), {"alpha", "beta"})
+            self.assertIn("gamma", updated["disabledPlugins"])
+
     def test_zip_to_pending_targets_ipa_pending(self) -> None:
         with tempfile.TemporaryDirectory() as tmp:
             work = Path(tmp)
@@ -1892,6 +1983,51 @@ class PluginHelperTuiTests(unittest.IsolatedAsyncioTestCase):
             self.assertNotIn("example", updated["disabledPlugins"])
             self.assertIn("Enabled 1 plugins", app.status_message)
 
+    async def test_save_known_good_records_currently_enabled_plugins(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            app, _instance, state = _make_two_plugin_tui_fixture(Path(tmp))
+
+            async with app.run_test() as pilot:
+                await pilot.press("s")
+                await pilot.pause()
+
+            from plugin_helper.state import load_known_good_state
+
+            known_good = load_known_good_state(state, "1.40.8")
+            self.assertEqual(known_good["pluginIds"], ["alpha", "beta"])
+            self.assertIn("Saved known-good set: 2 enabled plugins", app.status_message)
+
+    async def test_restore_known_good_reverts_manual_changes(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            app, instance, state = _make_two_plugin_tui_fixture(Path(tmp))
+
+            async with app.run_test() as pilot:
+                await pilot.press("s")
+                await pilot.pause()
+                # Manually disable beta after saving the known-good set.
+                await pilot.press("down")
+                await pilot.press("space")
+                await pilot.pause()
+                self.assertFalse((instance / "Plugins" / "Beta.dll").exists())
+
+                await pilot.press("g")
+                await pilot.pause()
+                self.assertIn("Restored known-good set", app.status_message)
+
+            self.assertTrue((instance / "Plugins" / "Beta.dll").exists())
+            updated = load_installed_state(state, "1.40.8")
+            self.assertEqual(set(updated["plugins"]), {"alpha", "beta"})
+
+    async def test_restore_known_good_without_saved_set_reports_status(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            app, _instance, _state = _make_two_plugin_tui_fixture(Path(tmp))
+
+            async with app.run_test() as pilot:
+                await pilot.press("g")
+                await pilot.pause()
+
+            self.assertIn("No known-good set saved yet", app.status_message)
+
     async def test_space_reports_hash_mismatch_without_state_update(self) -> None:
         with tempfile.TemporaryDirectory() as tmp:
             app, instance, state = _make_tui_fixture(Path(tmp), hash_mismatch=True)