refactor patch management and add ownership safeguards

1 files changed, 685 insertions, 0 deletions

diff --git a/backend/patcher.py b/backend/patcher.py
new file mode 100644
index 0000000..59d08f1
--- /dev/null
+++ b/backend/patcher.py
@@ -0,0 +1,685 @@
+"""Patch ownership, safe cleanup, and Steam-game operations."""
+
+import os
+import shutil
+from datetime import datetime, timezone
+from pathlib import Path
+from typing import Callable
+
+from . import config
+from .assets import (
+    BACKUP_DIRECTORY_NAME,
+    FRAMEGEN_BACKENDS,
+    FSR4_UPSCALER_FILENAME,
+    INJECTOR_FILENAMES,
+    MARKER_FILENAME,
+    MANIFEST_SCHEMA_VERSION,
+    RESTORABLE_BACKUP_FILES,
+    SUPPORT_FILES,
+    VALID_DLL_NAMES,
+    VARIANT_EXTRA_FILENAMES,
+)
+from .bundle import BundleManager
+from .files import file_sha256, files_match, read_json, write_json
+from .steam import SteamLibrary
+
+
+Logger = Callable[[str], None]
+
+
+class PatchManager:
+    def __init__(self, home: Path, bundle: BundleManager, steam: SteamLibrary, logger: Logger):
+        self.home = home
+        self.bundle = bundle
+        self.steam = steam
+        self.logger = logger
+
+    def _log(self, message: str) -> None:
+        self.logger(f"[Framegen] {message}")
+
+    @staticmethod
+    def _relative_path(root: Path, path: Path) -> str:
+        return path.resolve().relative_to(root.resolve()).as_posix()
+
+    def _safe_path(self, root: Path, value: str | Path) -> Path:
+        candidate = Path(value)
+        if candidate.is_absolute():
+            resolved = candidate.resolve()
+        else:
+            resolved = (root / candidate).resolve()
+        try:
+            resolved.relative_to(root.resolve())
+        except ValueError as exc:
+            raise ValueError(f"Path escapes patch directory: {value}") from exc
+        return resolved
+
+    def _read_marker(self, marker_path: Path) -> dict:
+        return read_json(marker_path)
+
+    def _find_marker(self, install_root: Path, appid: str | None = None) -> Path | None:
+        if not install_root.exists():
+            return None
+        try:
+            markers = sorted(path for path in install_root.rglob(MARKER_FILENAME) if path.is_file())
+        except OSError:
+            return None
+        for marker in markers:
+            metadata = self._read_marker(marker)
+            if appid is None or str(metadata.get("appid")) == str(appid):
+                return marker
+        return None
+
+    def _marker_target(self, marker_path: Path, metadata: dict) -> Path:
+        target_value = metadata.get("target_relative") or metadata.get("target_dir") or str(marker_path.parent)
+        target = self._safe_path(marker_path.parent, target_value)
+        if not target.is_dir():
+            raise FileNotFoundError(f"Patch target directory does not exist: {target}")
+        return target
+
+    def _bundle_source_for_proxy(self, variant: str, dll_name: str) -> Path:
+        candidates = [
+            self.bundle.variant_proxy_path(variant, dll_name),
+            self.bundle.variant_injector_path(variant),
+            self.bundle.fgmod_path / "renames" / dll_name,
+            self.bundle.fgmod_path / "OptiScaler.dll",
+        ]
+        for candidate in candidates:
+            if candidate and candidate.exists():
+                return candidate
+        raise FileNotFoundError(f"No injector source found for {dll_name}")
+
+    def _copy_plan(self, target_dir: Path, variant: str) -> list[tuple[str, Path]]:
+        plan: list[tuple[str, Path]] = []
+        # The proxy is the only file selected by the user; all other files are bundle-owned.
+        plan.append(("__proxy__", self._bundle_source_for_proxy(variant, "dxgi.dll")))
+        for filename in SUPPORT_FILES:
+            source = self.bundle.fgmod_path / filename
+            if source.is_file():
+                plan.append((filename, source))
+        upscaler = self.bundle.variant_path(variant)
+        if upscaler.is_file():
+            plan.append((FSR4_UPSCALER_FILENAME, upscaler))
+        for extra in self.bundle.variant_extra_files(variant):
+            source = self.bundle.variant_extra_path(variant, extra["name"])
+            if source.is_file():
+                plan.append((extra["name"], source))
+
+        for source_root, relative_root in (
+            (self.bundle.fgmod_path / "plugins", Path("plugins")),
+            (self.bundle.fgmod_path / "D3D12_Optiscaler", Path("D3D12_Optiscaler")),
+        ):
+            if not source_root.is_dir():
+                continue
+            for source in sorted(path for path in source_root.rglob("*") if path.is_file()):
+                plan.append(((relative_root / source.relative_to(source_root)).as_posix(), source))
+        return plan
+
+    def _backup_destination(self, target_dir: Path, relative: str, source: Path, force: bool = False) -> str | None:
+        destination = self._safe_path(target_dir, relative)
+        if not destination.exists():
+            return None
+        if destination.is_dir():
+            raise IsADirectoryError(f"Patch destination is a directory: {destination}")
+        if not force and files_match(destination, source):
+            return None
+
+        if relative in RESTORABLE_BACKUP_FILES:
+            legacy_backup = destination.with_name(destination.name + ".b")
+            if not legacy_backup.exists():
+                shutil.copy2(destination, legacy_backup)
+            elif not files_match(legacy_backup, destination):
+                raise RuntimeError(f"Refusing to overwrite an existing backup: {legacy_backup}")
+            return self._relative_path(target_dir, legacy_backup)
+
+        backup = target_dir / BACKUP_DIRECTORY_NAME / relative
+        backup.parent.mkdir(parents=True, exist_ok=True)
+        if backup.exists():
+            if not files_match(backup, destination):
+                raise RuntimeError(f"Refusing to overwrite an existing backup: {backup}")
+        else:
+            shutil.copy2(destination, backup)
+        return self._relative_path(target_dir, backup)
+
+    def _cleanup_empty_directories(self, target_dir: Path, managed_files: list[str]) -> None:
+        directories = sorted(
+            {self._safe_path(target_dir, path).parent for path in managed_files},
+            key=lambda path: len(path.parts),
+            reverse=True,
+        )
+        for directory in directories:
+            if directory == target_dir:
+                continue
+            try:
+                directory.rmdir()
+            except OSError:
+                pass
+        backup_dir = target_dir / BACKUP_DIRECTORY_NAME
+        try:
+            backup_dir.rmdir()
+        except OSError:
+            pass
+
+    def _rollback(
+        self,
+        target_dir: Path,
+        managed: list[dict],
+        backups: list[dict],
+    ) -> None:
+        for entry in reversed(managed):
+            try:
+                path = self._safe_path(target_dir, entry["path"])
+                backup = next((item["backup"] for item in backups if item["path"] == entry["path"]), None)
+                if backup:
+                    backup_path = self._safe_path(target_dir, backup)
+                    if backup_path.exists():
+                        if path.exists():
+                            path.unlink()
+                        shutil.move(backup_path, path)
+                elif path.exists() and entry.get("sha256") == file_sha256(path):
+                    path.unlink()
+            except (OSError, ValueError):
+                continue
+        self._cleanup_empty_directories(target_dir, [entry["path"] for entry in managed])
+
+    def _patch_directory(
+        self,
+        target_dir: Path,
+        dll_name: str,
+        variant: str,
+        framegen_backend: str,
+        *,
+        appid: str,
+        game_name: str,
+        original_launch_options: str,
+        previous_variant: str | None = None,
+    ) -> dict:
+        if dll_name not in VALID_DLL_NAMES:
+            return {"status": "error", "message": f"Invalid proxy DLL name: {dll_name}"}
+        if not self.bundle.fgmod_path.exists() or not (self.bundle.fgmod_path / "OptiScaler.dll").exists():
+            return {"status": "error", "message": "OptiScaler bundle not installed. Run Install first."}
+
+        variant = self.bundle.selected_variant(variant)
+        framegen_backend = self.bundle.selected_backend(framegen_backend)
+        previous_marker = target_dir / MARKER_FILENAME
+        if previous_marker.exists():
+            return {"status": "error", "message": f"Patch marker already exists in {target_dir}; clean it up before patching."}
+        variant_overrides = self.bundle.variant_config_overrides(variant)
+        if previous_variant == "rdna2-valve-411-pre10" and variant != previous_variant:
+            variant_overrides.setdefault("FSR.Fsr4ForceModel", "auto")
+            variant_overrides.setdefault("Plugins.LoadCustomAmdxc64OnRdna2", "false")
+
+        managed: list[dict] = []
+        backups: list[dict] = []
+        try:
+            plan = self._copy_plan(target_dir, variant)
+            proxy_source = self._bundle_source_for_proxy(variant, dll_name)
+            plan[0] = (dll_name, proxy_source)
+            config_path = target_dir / "OptiScaler.ini"
+            if config_path.exists():
+                plan.append(("OptiScaler.ini", config_path))
+            elif (self.bundle.fgmod_path / "OptiScaler.ini").exists():
+                plan.append(("OptiScaler.ini", self.bundle.fgmod_path / "OptiScaler.ini"))
+
+            for relative, source in plan:
+                destination = self._safe_path(target_dir, relative)
+                if not source.is_file():
+                    continue
+                backup = self._backup_destination(
+                    target_dir,
+                    relative,
+                    source,
+                    # Preserve every pre-existing destination. Identical bytes do
+                    # not prove that a file belongs to this plugin.
+                    force=destination.exists(),
+                )
+                if backup:
+                    backups.append({
+                        "path": relative,
+                        "backup": backup,
+                        "sha256": file_sha256(self._safe_path(target_dir, backup)),
+                    })
+                destination.parent.mkdir(parents=True, exist_ok=True)
+                if destination.resolve() != source.resolve():
+                    shutil.copy2(source, destination)
+                managed.append({
+                    "path": relative,
+                    "sha256": file_sha256(destination),
+                    "source_sha256": file_sha256(source),
+                })
+
+            if config_path.exists() and not config.configure(
+                config_path,
+                framegen_backend,
+                variant_overrides=variant_overrides,
+                logger=self.logger,
+            ):
+                raise RuntimeError("Could not update OptiScaler.ini")
+            config_entry = next((entry for entry in managed if entry["path"] == "OptiScaler.ini"), None)
+            if config_entry:
+                config_entry["sha256"] = file_sha256(config_path)
+
+            payload = {
+                "schema_version": MANIFEST_SCHEMA_VERSION,
+                "appid": str(appid),
+                "game_name": game_name,
+                "dll_name": dll_name,
+                "target_dir": str(target_dir),
+                "target_relative": ".",
+                "original_launch_options": original_launch_options,
+                "backed_up_files": [item["path"] for item in backups],
+                "backups": backups,
+                "managed_files": managed,
+                "managed_directories": sorted({str(Path(item["path"]).parent) for item in managed if Path(item["path"]).parent != Path(".")}),
+                "optiscaler_version": self.bundle.fgmod_version(),
+                "fsr4_variant": variant,
+                "fsr4_variant_label": self.bundle.variant_info(variant)["label"],
+                "fsr4_upscaler_sha256": file_sha256(target_dir / FSR4_UPSCALER_FILENAME) if (target_dir / FSR4_UPSCALER_FILENAME).exists() else None,
+                "framegen_backend": framegen_backend,
+                "framegen_backend_label": FRAMEGEN_BACKENDS[framegen_backend],
+                "patched_at": datetime.now(timezone.utc).isoformat(),
+            }
+            # The marker is written last, so an interrupted copy is never advertised as a complete patch.
+            write_json(previous_marker, payload)
+            return {
+                "status": "success",
+                "message": f"OptiScaler files copied to {target_dir} using {self.bundle.variant_info(variant)['label']}",
+                "fsr4_variant": variant,
+                "fsr4_variant_label": self.bundle.variant_info(variant)["label"],
+                "fsr4_upscaler_sha256": payload["fsr4_upscaler_sha256"],
+                "optiscaler_version": payload["optiscaler_version"],
+                "framegen_backend": framegen_backend,
+            }
+        except (OSError, RuntimeError, ValueError) as exc:
+            self._rollback(target_dir, managed, backups)
+            self._log(f"Patch failed for {target_dir}: {exc}")
+            return {"status": "error", "message": f"Patch failed: {exc}"}
+
+    def _managed_entries(self, target_dir: Path, metadata: dict) -> tuple[list[tuple[dict, Path]], list[str]]:
+        entries: list[tuple[dict, Path]] = []
+        errors: list[str] = []
+        for entry in metadata.get("managed_files", []):
+            if not isinstance(entry, dict) or not entry.get("path"):
+                errors.append("Patch marker contains an invalid managed file entry.")
+                continue
+            try:
+                path = self._safe_path(target_dir, entry["path"])
+            except ValueError as exc:
+                errors.append(str(exc))
+                continue
+            expected = str(entry.get("sha256") or "")
+            if not expected:
+                errors.append(f"Patch marker has no hash for {entry['path']}.")
+            elif path.exists() and (not path.is_file() or file_sha256(path).lower() != expected.lower()):
+                errors.append(f"Refusing to remove modified managed file: {path}")
+            entries.append((entry, path))
+        return entries, errors
+
+    def _restore_backups(self, target_dir: Path, metadata: dict) -> list[str]:
+        restored: list[str] = []
+        for item in metadata.get("backups", []):
+            if not isinstance(item, dict) or not item.get("path") or not item.get("backup"):
+                raise ValueError("Patch marker contains an invalid backup entry.")
+            path = self._safe_path(target_dir, item["path"])
+            backup = self._safe_path(target_dir, item["backup"])
+            if not backup.exists():
+                continue
+            if not backup.is_file():
+                raise ValueError(f"Patch backup is not a file: {backup}")
+            expected = str(item.get("sha256") or "")
+            if expected and file_sha256(backup).lower() != expected.lower():
+                raise RuntimeError(f"Refusing to restore a modified backup: {backup}")
+            if path.exists():
+                raise RuntimeError(f"Refusing to overwrite a file while restoring backup: {path}")
+            path.parent.mkdir(parents=True, exist_ok=True)
+            shutil.move(backup, path)
+            restored.append(str(item["path"]))
+
+        # Older releases used ``name.b`` backups and listed only their base names.
+        for raw_name in metadata.get("backed_up_files", []):
+            name = Path(str(raw_name)).name
+            if name not in RESTORABLE_BACKUP_FILES:
+                continue
+            original = self._safe_path(target_dir, name)
+            backup = self._safe_path(target_dir, name + ".b")
+            if backup.exists() and not original.exists():
+                shutil.move(backup, original)
+                restored.append(name)
+        return restored
+
+    def _validate_backups(self, target_dir: Path, metadata: dict) -> None:
+        for item in metadata.get("backups", []):
+            if not isinstance(item, dict) or not item.get("path") or not item.get("backup"):
+                raise ValueError("Patch marker contains an invalid backup entry.")
+            self._safe_path(target_dir, item["path"])
+            backup = self._safe_path(target_dir, item["backup"])
+            if not backup.exists():
+                continue
+            if not backup.is_file():
+                raise ValueError(f"Patch backup is not a file: {backup}")
+            expected = str(item.get("sha256") or "")
+            if expected and file_sha256(backup).lower() != expected.lower():
+                raise RuntimeError(f"Refusing to restore a modified backup: {backup}")
+
+    def _legacy_owned_paths(self, target_dir: Path, metadata: dict) -> list[Path]:
+        paths: list[Path] = []
+        for entry in metadata.get("managed_files", []):
+            if isinstance(entry, dict) and entry.get("path"):
+                try:
+                    paths.append(self._safe_path(target_dir, entry["path"]))
+                except ValueError:
+                    continue
+
+        variant = self.bundle.normalize_variant(metadata.get("fsr4_variant"))
+        proxy_sources = [
+            self.bundle.fgmod_path / "OptiScaler.dll",
+            self.bundle.fgmod_path / "renames",
+            self.bundle.variant_dir(variant) / "renames",
+        ]
+        for filename in INJECTOR_FILENAMES:
+            target = target_dir / filename
+            if not target.is_file():
+                continue
+            matches_bundle = False
+            for source in proxy_sources:
+                candidate = source if source.is_file() and source.name == filename else source / filename
+                if candidate.is_file() and files_match(target, candidate):
+                    matches_bundle = True
+                    break
+            if matches_bundle:
+                paths.append(target)
+        for filename in SUPPORT_FILES + VARIANT_EXTRA_FILENAMES + [FSR4_UPSCALER_FILENAME]:
+            target = target_dir / filename
+            if target.is_file() and self.bundle.is_managed_support_file(target):
+                paths.append(target)
+        for relative in (Path("plugins/OptiPatcher.asi"),):
+            target = target_dir / relative
+            source = self.bundle.fgmod_path / relative
+            if target.is_file() and source.is_file() and files_match(target, source):
+                paths.append(target)
+        d3d12_source = self.bundle.fgmod_path / "D3D12_Optiscaler"
+        d3d12_target = target_dir / "D3D12_Optiscaler"
+        if d3d12_source.is_dir() and d3d12_target.is_dir():
+            for source in d3d12_source.rglob("*"):
+                if source.is_file():
+                    candidate = d3d12_target / source.relative_to(d3d12_source)
+                    if candidate.is_file() and files_match(candidate, source):
+                        paths.append(candidate)
+        unique: list[Path] = []
+        seen: set[str] = set()
+        for path in paths:
+            if str(path) not in seen:
+                unique.append(path)
+                seen.add(str(path))
+        return unique
+
+    def _unpatch_target(self, target_dir: Path, marker_path: Path | None) -> dict:
+        metadata = self._read_marker(marker_path) if marker_path else {
+            "backed_up_files": [
+                name for name in RESTORABLE_BACKUP_FILES
+                if (target_dir / f"{name}.b").is_file()
+            ],
+        }
+        try:
+            if marker_path and marker_path.exists() and not metadata:
+                return {"status": "error", "message": f"Patch marker is unreadable: {marker_path}"}
+            schema_version = int(metadata.get("schema_version") or 1) if metadata else 1
+            if schema_version >= MANIFEST_SCHEMA_VERSION:
+                entries, errors = self._managed_entries(target_dir, metadata)
+                if errors:
+                    return {"status": "error", "message": " ".join(errors)}
+                self._validate_backups(target_dir, metadata)
+                managed_paths = [path for _, path in entries]
+                for _, path in entries:
+                    if path.exists():
+                        path.unlink()
+                restored = self._restore_backups(target_dir, metadata)
+                self._cleanup_empty_directories(target_dir, [str(path.relative_to(target_dir)) for path in managed_paths])
+            else:
+                owned = self._legacy_owned_paths(target_dir, metadata)
+                entries, errors = self._managed_entries(target_dir, metadata)
+                if errors:
+                    return {"status": "error", "message": " ".join(errors)}
+                owned.extend(path for _, path in entries if path not in owned)
+                for path in owned:
+                    if path.is_file():
+                        path.unlink()
+                restored = self._restore_backups(target_dir, metadata)
+                self._cleanup_empty_directories(target_dir, [str(path.relative_to(target_dir)) for path in owned])
+            if marker_path and marker_path.exists():
+                marker_path.unlink()
+            return {
+                "status": "success",
+                "message": f"OptiScaler files removed from {target_dir}",
+                "restored_files": restored,
+            }
+        except (OSError, RuntimeError, ValueError) as exc:
+            self._log(f"Unpatch failed for {target_dir}: {exc}")
+            return {"status": "error", "message": f"Unpatch failed: {exc}"}
+
+    def resolve_target_directory(self, directory: str) -> Path:
+        target = Path(directory).expanduser()
+        if not target.exists():
+            raise FileNotFoundError(f"Target directory does not exist: {directory}")
+        if not target.is_dir():
+            raise NotADirectoryError(f"Target path is not a directory: {directory}")
+        if not os.access(target, os.W_OK | os.X_OK):
+            raise PermissionError(f"Insufficient permissions for {directory}")
+        return target.resolve()
+
+    def manual_patch_directory(
+        self,
+        directory: str,
+        dll_name: str,
+        fsr4_variant: str,
+        framegen_backend: str | None = None,
+    ) -> dict:
+        try:
+            target = self.resolve_target_directory(directory)
+        except (FileNotFoundError, NotADirectoryError, PermissionError) as exc:
+            return {"status": "error", "message": str(exc)}
+        marker = target / MARKER_FILENAME
+        previous_metadata = self._read_marker(marker) if marker.exists() else {}
+        previous_variant = previous_metadata.get("fsr4_variant")
+        if marker.exists():
+            if str(previous_metadata.get("appid")) not in ("", "manual", "None"):
+                return {"status": "error", "message": "This directory is managed by an AppID patch; unpatch it there first."}
+            cleanup = self._unpatch_target(target, marker)
+            if cleanup["status"] != "success":
+                return cleanup
+        return self._patch_directory(
+            target,
+            dll_name,
+            self.bundle.selected_variant(fsr4_variant),
+            self.bundle.selected_backend(framegen_backend),
+            appid="manual",
+            game_name="Manual patch",
+            original_launch_options="",
+            previous_variant=previous_variant,
+        )
+
+    def manual_unpatch_directory(self, directory: str) -> dict:
+        try:
+            target = self.resolve_target_directory(directory)
+        except (FileNotFoundError, NotADirectoryError, PermissionError) as exc:
+            return {"status": "error", "message": str(exc)}
+        marker = target / MARKER_FILENAME
+        return self._unpatch_target(target, marker if marker.exists() else None)
+
+    def list_installed_games(self) -> dict:
+        try:
+            return {
+                "status": "success",
+                "games": [
+                    {
+                        "appid": str(game["appid"]),
+                        "name": game["name"],
+                        "install_found": Path(game["install_path"]).exists(),
+                    }
+                    for game in self.steam.find_installed_games()
+                ],
+            }
+        except Exception as exc:
+            self._log(str(exc))
+            return {"status": "error", "message": str(exc)}
+
+    def get_game_status(self, appid: str) -> dict:
+        try:
+            game_info = self.steam.game_record(str(appid))
+            if not game_info:
+                return {
+                    "status": "success", "appid": str(appid), "install_found": False, "patched": False,
+                    "dll_name": None, "target_dir": None, "fsr4_variant": None, "fsr4_variant_label": None,
+                    "framegen_backend": None, "message": "Game not found in Steam library.",
+                }
+            install_root = Path(game_info["install_path"])
+            base = {
+                "status": "success", "appid": str(appid), "name": game_info["name"],
+                "install_found": install_root.exists(), "patched": False, "dll_name": None,
+                "target_dir": None, "fsr4_variant": None, "fsr4_variant_label": None,
+                "framegen_backend": None,
+            }
+            if not install_root.exists():
+                return {**base, "message": "Game install directory not found."}
+            marker = self._find_marker(install_root, str(appid))
+            if not marker:
+                return {**base, "message": "Not patched."}
+            metadata = self._read_marker(marker)
+            target_dir = self._marker_target(marker, metadata)
+            dll_name = str(metadata.get("dll_name") or "dxgi.dll")
+            upscaler = target_dir / FSR4_UPSCALER_FILENAME
+            upscaler_sha256 = file_sha256(upscaler) if upscaler.is_file() else None
+            variant = self.bundle.detect_variant(target_dir, upscaler_sha256) or self.bundle.normalize_variant(metadata.get("fsr4_variant"))
+            backend = self.bundle.normalize_backend(metadata.get("framegen_backend") or self.bundle.selected_backend())
+            dll_present = (target_dir / dll_name).is_file()
+            return {
+                **base,
+                "patched": dll_present,
+                "dll_name": dll_name,
+                "target_dir": str(target_dir),
+                "patched_at": metadata.get("patched_at"),
+                "optiscaler_version": metadata.get("optiscaler_version"),
+                "fsr4_variant": variant,
+                "fsr4_variant_label": self.bundle.variant_info(variant)["label"],
+                "fsr4_upscaler_sha256": upscaler_sha256,
+                "framegen_backend": backend,
+                "framegen_backend_label": FRAMEGEN_BACKENDS[backend],
+                "message": f"Patched using {dll_name} with {self.bundle.variant_info(variant)['label']}." if dll_present else f"Marker found but {dll_name} is missing. Reinstall recommended.",
+            }
+        except Exception as exc:
+            self._log(f"get_game_status failed for {appid}: {exc}")
+            return {"status": "error", "message": str(exc)}
+
+    @staticmethod
+    def build_managed_launch_options(dll_name: str) -> str:
+        if dll_name == "OptiScaler.asi":
+            return "SteamDeck=0 %command%"
+        base = dll_name.replace(".dll", "")
+        return f"WINEDLLOVERRIDES={base}=n,b SteamDeck=0 %command%"
+
+    @staticmethod
+    def is_managed_launch_options(options: str) -> bool:
+        normalized = " ".join((options or "").replace('"', "").split())
+        if not normalized:
+            return False
+        return any(
+            dll_name != "OptiScaler.asi" and f"WINEDLLOVERRIDES={dll_name.replace('.dll', '')}=n,b" in normalized
+            for dll_name in VALID_DLL_NAMES
+        ) or "fgmod/fgmod" in normalized
+
+    def patch_game(
+        self,
+        appid: str,
+        dll_name: str,
+        current_launch_options: str,
+        fsr4_variant: str,
+        framegen_backend: str | None = None,
+    ) -> dict:
+        try:
+            if dll_name not in VALID_DLL_NAMES:
+                return {"status": "error", "message": f"Invalid proxy DLL name: {dll_name}"}
+            game_info = self.steam.game_record(str(appid))
+            if not game_info:
+                return {"status": "error", "message": "Game not found in Steam library."}
+            install_root = Path(game_info["install_path"])
+            if not install_root.exists():
+                return {"status": "error", "message": "Game install directory does not exist."}
+            if self.steam.is_game_running(game_info):
+                return {"status": "error", "message": "Close the game before patching."}
+            if not self.bundle.fgmod_path.exists():
+                return {"status": "error", "message": "OptiScaler bundle not installed. Run Install first."}
+
+            existing_marker = self._find_marker(install_root)
+            existing_metadata = self._read_marker(existing_marker) if existing_marker else {}
+            if existing_marker and str(existing_metadata.get("appid")) not in (str(appid), "manual", "None"):
+                return {"status": "error", "message": "Another Framegen patch marker was found in this game install."}
+            original_options = current_launch_options or ""
+            stored_options = str(existing_metadata.get("original_launch_options") or "")
+            if stored_options and not self.is_managed_launch_options(stored_options):
+                original_options = stored_options
+            if self.is_managed_launch_options(original_options):
+                original_options = ""
+
+            if existing_marker:
+                old_target = self._marker_target(existing_marker, existing_metadata)
+                cleanup = self._unpatch_target(old_target, existing_marker)
+                if cleanup["status"] != "success":
+                    return cleanup
+            target_dir, _ = self.steam.guess_patch_target(game_info)
+            result = self._patch_directory(
+                target_dir,
+                dll_name,
+                self.bundle.selected_variant(fsr4_variant),
+                self.bundle.selected_backend(framegen_backend),
+                appid=str(appid),
+                game_name=game_info["name"],
+                original_launch_options=original_options,
+                previous_variant=existing_metadata.get("fsr4_variant"),
+            )
+            if result["status"] != "success":
+                return result
+            backend = result.get("framegen_backend") or self.bundle.selected_backend(framegen_backend)
+            return {
+                **result,
+                "appid": str(appid),
+                "name": game_info["name"],
+                "dll_name": dll_name,
+                "target_dir": str(target_dir),
+                "launch_options": self.build_managed_launch_options(dll_name),
+                "original_launch_options": original_options,
+                "framegen_backend": backend,
+                "message": f"Patched {game_info['name']} using {dll_name} with {result.get('fsr4_variant_label') or self.bundle.variant_info(fsr4_variant)['label']}.",
+            }
+        except Exception as exc:
+            self._log(f"patch_game failed for {appid}: {exc}")
+            return {"status": "error", "message": str(exc)}
+
+    def unpatch_game(self, appid: str) -> dict:
+        try:
+            game_info = self.steam.game_record(str(appid))
+            if not game_info:
+                return {"status": "error", "message": "Game not found in Steam library."}
+            install_root = Path(game_info["install_path"])
+            if not install_root.exists():
+                return {"status": "success", "appid": str(appid), "name": game_info["name"], "launch_options": "", "message": "Game install directory does not exist."}
+            if self.steam.is_game_running(game_info):
+                return {"status": "error", "message": "Close the game before unpatching."}
+            marker = self._find_marker(install_root, str(appid))
+            if not marker:
+                return {"status": "success", "appid": str(appid), "name": game_info["name"], "launch_options": "", "message": "No Framegen patch found for this game."}
+            metadata = self._read_marker(marker)
+            target_dir = self._marker_target(marker, metadata)
+            original_options = str(metadata.get("original_launch_options") or "")
+            cleanup = self._unpatch_target(target_dir, marker)
+            if cleanup["status"] != "success":
+                return {**cleanup, "appid": str(appid), "name": game_info["name"]}
+            self._log(f"unpatch_game success: appid={appid} target={target_dir}")
+            return {
+                "status": "success",
+                "appid": str(appid),
+                "name": game_info["name"],
+                "launch_options": original_options,
+                "message": f"Unpatched {game_info['name']}.",
+            }
+        except Exception as exc:
+            self._log(f"unpatch_game failed for {appid}: {exc}")
+            return {"status": "error", "message": str(exc)}