Add: support for user-global configuration.

README.md

@@ -169,11 +169,17 @@ whatever is nearly done and then quits regardless.
 
 ## Files it writes
 
-Everything lives in `config/photosync/` in your game directory:
+By default everything lives in `config/photosync/` in your game directory:
 
 - `photosync.json` — settings, including your API key. Back it up accordingly.
 - `uploads.json` — the upload queue, so it survives a crash or a quit.
 
+Turn on *Store settings outside the game folder* in Settings → Storage and
+`photosync.json` moves to `~/.config/photosyncmod/` on Linux and macOS, or
+`%APPDATA%\photosyncmod\` on Windows, shared across your Minecraft installs.
+The game folder keeps `uploads.json` and a small `location.json` pointer that
+says where the settings file went.
+
 Screenshots themselves go where they always did, in `screenshots/`. PhotoSync
 never moves them, and only deletes one if you asked it to and the upload was
 confirmed.

platform/1.20.1/src/main/java/dev/photosync/platform/impl/GameAdapter.java

@@ -2,6 +2,7 @@ package dev.photosync.platform.impl;
 
 import dev.photosync.core.capture.CameraPose;
 import dev.photosync.mcapi.GameContext;
+import dev.photosync.platform.UserDataDirectory;
 import dev.photosync.platform.WindowTitle;
 import lombok.extern.slf4j.Slf4j;
 import net.fabricmc.loader.api.FabricLoader;
@@ -23,6 +24,7 @@ public final class GameAdapter implements GameContext {
      * loader's answers have not moved once in the supported range.
      */
     private final Path configDirectory = FabricLoader.getInstance().getConfigDir().resolve("photosync");
+    private final Path userDataDirectory = UserDataDirectory.resolve();
     private final String minecraftVersion = FabricLoader.getInstance()
             .getModContainer("minecraft")
             .map(container -> container.getMetadata().getVersion().getFriendlyString())
@@ -57,6 +59,11 @@ public final class GameAdapter implements GameContext {
         return configDirectory;
     }
 
+    @Override
+    public Path userDataDirectory() {
+        return userDataDirectory;
+    }
+
     @Override
     public void submit(Runnable task) {
         Minecraft game = Minecraft.getInstance();

platform/1.20.4/src/main/java/dev/photosync/platform/impl/GameAdapter.java

@@ -2,6 +2,7 @@ package dev.photosync.platform.impl;
 
 import dev.photosync.core.capture.CameraPose;
 import dev.photosync.mcapi.GameContext;
+import dev.photosync.platform.UserDataDirectory;
 import dev.photosync.platform.WindowTitle;
 import lombok.extern.slf4j.Slf4j;
 import net.fabricmc.loader.api.FabricLoader;
@@ -23,6 +24,7 @@ public final class GameAdapter implements GameContext {
      * loader's answers have not moved once in the supported range.
      */
     private final Path configDirectory = FabricLoader.getInstance().getConfigDir().resolve("photosync");
+    private final Path userDataDirectory = UserDataDirectory.resolve();
     private final String minecraftVersion = FabricLoader.getInstance()
             .getModContainer("minecraft")
             .map(container -> container.getMetadata().getVersion().getFriendlyString())
@@ -57,6 +59,11 @@ public final class GameAdapter implements GameContext {
         return configDirectory;
     }
 
+    @Override
+    public Path userDataDirectory() {
+        return userDataDirectory;
+    }
+
     @Override
     public void submit(Runnable task) {
         Minecraft game = Minecraft.getInstance();

platform/1.20.6/src/main/java/dev/photosync/platform/impl/GameAdapter.java

@@ -2,6 +2,7 @@ package dev.photosync.platform.impl;
 
 import dev.photosync.core.capture.CameraPose;
 import dev.photosync.mcapi.GameContext;
+import dev.photosync.platform.UserDataDirectory;
 import dev.photosync.platform.WindowTitle;
 import lombok.extern.slf4j.Slf4j;
 import net.fabricmc.loader.api.FabricLoader;
@@ -23,6 +24,7 @@ public final class GameAdapter implements GameContext {
      * loader's answers have not moved once in the supported range.
      */
     private final Path configDirectory = FabricLoader.getInstance().getConfigDir().resolve("photosync");
+    private final Path userDataDirectory = UserDataDirectory.resolve();
     private final String minecraftVersion = FabricLoader.getInstance()
             .getModContainer("minecraft")
             .map(container -> container.getMetadata().getVersion().getFriendlyString())
@@ -57,6 +59,11 @@ public final class GameAdapter implements GameContext {
         return configDirectory;
     }
 
+    @Override
+    public Path userDataDirectory() {
+        return userDataDirectory;
+    }
+
     @Override
     public void submit(Runnable task) {
         Minecraft game = Minecraft.getInstance();

platform/1.21.1/src/main/java/dev/photosync/platform/impl/GameAdapter.java

@@ -2,6 +2,7 @@ package dev.photosync.platform.impl;
 
 import dev.photosync.core.capture.CameraPose;
 import dev.photosync.mcapi.GameContext;
+import dev.photosync.platform.UserDataDirectory;
 import dev.photosync.platform.WindowTitle;
 import lombok.extern.slf4j.Slf4j;
 import net.fabricmc.loader.api.FabricLoader;
@@ -23,6 +24,7 @@ public final class GameAdapter implements GameContext {
      * loader's answers have not moved once in the supported range.
      */
     private final Path configDirectory = FabricLoader.getInstance().getConfigDir().resolve("photosync");
+    private final Path userDataDirectory = UserDataDirectory.resolve();
     private final String minecraftVersion = FabricLoader.getInstance()
             .getModContainer("minecraft")
             .map(container -> container.getMetadata().getVersion().getFriendlyString())
@@ -57,6 +59,11 @@ public final class GameAdapter implements GameContext {
         return configDirectory;
     }
 
+    @Override
+    public Path userDataDirectory() {
+        return userDataDirectory;
+    }
+
     @Override
     public void submit(Runnable task) {
         Minecraft game = Minecraft.getInstance();

platform/1.21.11/src/main/java/dev/photosync/platform/impl/GameAdapter.java

@@ -2,6 +2,7 @@ package dev.photosync.platform.impl;
 
 import dev.photosync.core.capture.CameraPose;
 import dev.photosync.mcapi.GameContext;
+import dev.photosync.platform.UserDataDirectory;
 import dev.photosync.platform.WindowTitle;
 import lombok.extern.slf4j.Slf4j;
 import net.fabricmc.loader.api.FabricLoader;
@@ -23,6 +24,7 @@ public final class GameAdapter implements GameContext {
      * loader's answers have not moved once in the supported range.
      */
     private final Path configDirectory = FabricLoader.getInstance().getConfigDir().resolve("photosync");
+    private final Path userDataDirectory = UserDataDirectory.resolve();
     private final String minecraftVersion = FabricLoader.getInstance()
             .getModContainer("minecraft")
             .map(container -> container.getMetadata().getVersion().getFriendlyString())
@@ -57,6 +59,11 @@ public final class GameAdapter implements GameContext {
         return configDirectory;
     }
 
+    @Override
+    public Path userDataDirectory() {
+        return userDataDirectory;
+    }
+
     @Override
     public void submit(Runnable task) {
         Minecraft game = Minecraft.getInstance();

platform/1.21.4/src/main/java/dev/photosync/platform/impl/GameAdapter.java

@@ -2,6 +2,7 @@ package dev.photosync.platform.impl;
 
 import dev.photosync.core.capture.CameraPose;
 import dev.photosync.mcapi.GameContext;
+import dev.photosync.platform.UserDataDirectory;
 import dev.photosync.platform.WindowTitle;
 import lombok.extern.slf4j.Slf4j;
 import net.fabricmc.loader.api.FabricLoader;
@@ -23,6 +24,7 @@ public final class GameAdapter implements GameContext {
      * loader's answers have not moved once in the supported range.
      */
     private final Path configDirectory = FabricLoader.getInstance().getConfigDir().resolve("photosync");
+    private final Path userDataDirectory = UserDataDirectory.resolve();
     private final String minecraftVersion = FabricLoader.getInstance()
             .getModContainer("minecraft")
             .map(container -> container.getMetadata().getVersion().getFriendlyString())
@@ -57,6 +59,11 @@ public final class GameAdapter implements GameContext {
         return configDirectory;
     }
 
+    @Override
+    public Path userDataDirectory() {
+        return userDataDirectory;
+    }
+
     @Override
     public void submit(Runnable task) {
         Minecraft game = Minecraft.getInstance();

platform/1.21.5/src/main/java/dev/photosync/platform/impl/GameAdapter.java

@@ -2,6 +2,7 @@ package dev.photosync.platform.impl;
 
 import dev.photosync.core.capture.CameraPose;
 import dev.photosync.mcapi.GameContext;
+import dev.photosync.platform.UserDataDirectory;
 import dev.photosync.platform.WindowTitle;
 import lombok.extern.slf4j.Slf4j;
 import net.fabricmc.loader.api.FabricLoader;
@@ -23,6 +24,7 @@ public final class GameAdapter implements GameContext {
      * loader's answers have not moved once in the supported range.
      */
     private final Path configDirectory = FabricLoader.getInstance().getConfigDir().resolve("photosync");
+    private final Path userDataDirectory = UserDataDirectory.resolve();
     private final String minecraftVersion = FabricLoader.getInstance()
             .getModContainer("minecraft")
             .map(container -> container.getMetadata().getVersion().getFriendlyString())
@@ -57,6 +59,11 @@ public final class GameAdapter implements GameContext {
         return configDirectory;
     }
 
+    @Override
+    public Path userDataDirectory() {
+        return userDataDirectory;
+    }
+
     @Override
     public void submit(Runnable task) {
         Minecraft game = Minecraft.getInstance();

platform/1.21.8/src/main/java/dev/photosync/platform/impl/GameAdapter.java

@@ -2,6 +2,7 @@ package dev.photosync.platform.impl;
 
 import dev.photosync.core.capture.CameraPose;
 import dev.photosync.mcapi.GameContext;
+import dev.photosync.platform.UserDataDirectory;
 import dev.photosync.platform.WindowTitle;
 import lombok.extern.slf4j.Slf4j;
 import net.fabricmc.loader.api.FabricLoader;
@@ -23,6 +24,7 @@ public final class GameAdapter implements GameContext {
      * loader's answers have not moved once in the supported range.
      */
     private final Path configDirectory = FabricLoader.getInstance().getConfigDir().resolve("photosync");
+    private final Path userDataDirectory = UserDataDirectory.resolve();
     private final String minecraftVersion = FabricLoader.getInstance()
             .getModContainer("minecraft")
             .map(container -> container.getMetadata().getVersion().getFriendlyString())
@@ -57,6 +59,11 @@ public final class GameAdapter implements GameContext {
         return configDirectory;
     }
 
+    @Override
+    public Path userDataDirectory() {
+        return userDataDirectory;
+    }
+
     @Override
     public void submit(Runnable task) {
         Minecraft game = Minecraft.getInstance();

platform/26.2/src/main/java/dev/photosync/platform/impl/GameAdapter.java

@@ -2,6 +2,7 @@ package dev.photosync.platform.impl;
 
 import dev.photosync.core.capture.CameraPose;
 import dev.photosync.mcapi.GameContext;
+import dev.photosync.platform.UserDataDirectory;
 import dev.photosync.platform.WindowTitle;
 import lombok.extern.slf4j.Slf4j;
 import net.fabricmc.loader.api.FabricLoader;
@@ -23,6 +24,7 @@ public final class GameAdapter implements GameContext {
      * loader's answers have not moved once in the supported range.
      */
     private final Path configDirectory = FabricLoader.getInstance().getConfigDir().resolve("photosync");
+    private final Path userDataDirectory = UserDataDirectory.resolve();
     private final String minecraftVersion = FabricLoader.getInstance()
             .getModContainer("minecraft")
             .map(container -> container.getMetadata().getVersion().getFriendlyString())
@@ -58,6 +60,11 @@ public final class GameAdapter implements GameContext {
         return configDirectory;
     }
 
+    @Override
+    public Path userDataDirectory() {
+        return userDataDirectory;
+    }
+
     @Override
     public void submit(Runnable task) {
         Minecraft game = Minecraft.getInstance();

platform/common/src/main/java/dev/photosync/platform/UserDataDirectory.java

@@ -0,0 +1,25 @@
+package dev.photosync.platform;
+
+import java.nio.file.Path;
+
+/**
+ * The OS-user-level directory PhotoSync offers for its settings file.
+ *
+ * <p>One rule, written once: Windows keeps per-user application data under
+ * {@code %APPDATA%}, everything else under {@code ~/.config} (the convention
+ * the Linux desktops and macOS share). Nine buckets compile this class, so a
+ * fix to the rule needs one edit instead of nine.
+ */
+public final class UserDataDirectory {
+
+    private UserDataDirectory() {
+    }
+
+    public static Path resolve() {
+        String appData = System.getenv("APPDATA");
+        Path base = appData == null || appData.isBlank()
+                ? Path.of(System.getProperty("user.home"), ".config")
+                : Path.of(appData);
+        return base.resolve("photosyncmod");
+    }
+}

shared/client/src/main/java/dev/photosync/client/PhotoSyncClient.java

@@ -2,6 +2,7 @@ package dev.photosync.client;
 
 import dev.photosync.core.PhotoSync;
 import dev.photosync.core.capture.CapturedScreenshot;
+import dev.photosync.core.config.ConfigLocations;
 import dev.photosync.core.config.NotificationKind;
 import dev.photosync.core.config.PhotoSyncConfig;
 import dev.photosync.core.upload.UploadEvent;
@@ -52,7 +53,9 @@ public final class PhotoSyncClient implements AutoCloseable {
     private final AutoCapture autoCapture;
 
     public PhotoSyncClient(ClientBridge bridge) {
-        this(bridge, new PhotoSync(bridge.game().configDirectory()), Theme.dark());
+        this(bridge, new PhotoSync(new ConfigLocations(
+                bridge.game().configDirectory(),
+                bridge.game().userDataDirectory())), Theme.dark());
     }
 
     /** Takes its collaborators explicitly so a test can drive it without a game. */

shared/client/src/main/resources/assets/photosync/lang/en_us.json

@@ -98,6 +98,12 @@
   "photosync.settings.cache": "Thumbnails kept in memory",
   "photosync.settings.video_badge": "Mark videos in the grid",
 
+  "photosync.settings.section.storage": "Storage",
+  "photosync.settings.user_config_location": "Store settings outside the game folder",
+  "photosync.settings.user_config_location.detail": "Settings move to %s and are shared across your Minecraft installs. The upload queue stays in the game folder.",
+  "photosync.settings.config_folder": "Config folder",
+  "photosync.settings.show_folder": "Show in folder",
+
   "photosync.settings.save": "Save",
   "photosync.settings.revert": "Revert",
   "photosync.settings.dirty": "Unsaved changes -- saved when you close this screen.",

shared/client/src/main/resources/assets/photosync/lang/zh_cn.json

@@ -98,6 +98,12 @@
   "photosync.settings.cache": "内存中保留的缩略图数量",
   "photosync.settings.video_badge": "在网格中标记视频",
 
+  "photosync.settings.section.storage": "存储",
+  "photosync.settings.user_config_location": "将设置存储在游戏文件夹之外",
+  "photosync.settings.user_config_location.detail": "设置将移动到 %s，并在你的多个 Minecraft 安装之间共享。上传队列仍保留在游戏文件夹中。",
+  "photosync.settings.config_folder": "配置文件夹",
+  "photosync.settings.show_folder": "在文件夹中显示",
+
   "photosync.settings.save": "保存",
   "photosync.settings.revert": "还原",
   "photosync.settings.dirty": "有未保存的更改——关闭此界面时保存。",

shared/core/src/main/java/dev/photosync/core/PhotoSync.java

@@ -1,5 +1,7 @@
 package dev.photosync.core;
 
+import dev.photosync.core.config.ConfigLocation;
+import dev.photosync.core.config.ConfigLocations;
 import dev.photosync.core.config.ConfigService;
 import dev.photosync.core.config.ConfigStore;
 import dev.photosync.core.config.PhotoSyncConfig;
@@ -14,7 +16,10 @@ import dev.photosync.core.upload.UploadQueue;
 import lombok.Getter;
 import lombok.extern.slf4j.Slf4j;
 
+import java.io.IOException;
+import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
 import java.time.Duration;
 import java.util.List;
 
@@ -22,9 +27,9 @@ import java.util.List;
  * Everything the mod does that is not Minecraft, assembled.
  *
  * <p>This is the seam the platform code sees: a Fabric entrypoint builds one of
- * these with a config directory and then only ever talks to the services hanging
- * off it. Nothing below this package knows what a {@code Screen} is, and nothing
- * here reaches back up.
+ * these with a {@link ConfigLocations} -- where the settings file may live --
+ * and then only ever talks to the services hanging off it. Nothing below this
+ * package knows what a {@code Screen} is, and nothing here reaches back up.
  *
  * <p>The wiring is done in a constructor rather than by a container because
  * there are seven objects and their order is fixed. The one piece of behaviour
@@ -37,6 +42,10 @@ public final class PhotoSync implements AutoCloseable {
     private static final String CONFIG_FILE = "photosync.json";
     private static final String QUEUE_FILE = "uploads.json";
 
+    @Getter
+    private final ConfigLocations locations;
+    private volatile ConfigLocation activeLocation;
+
     @Getter
     private final ProviderCatalog catalog;
     @Getter
@@ -52,19 +61,33 @@ public final class PhotoSync implements AutoCloseable {
     @Getter
     private final ThumbnailLoader thumbnails;
 
-    /** The standard set of backends. */
+    /** The standard set of backends, stored in the given directory. */
     public PhotoSync(Path directory) {
-        this(directory, List.of(new ImmichProviderFactory()));
+        this(ConfigLocations.fixed(directory), List.of(new ImmichProviderFactory()));
     }
 
     /** Takes the backend list explicitly so tests can run against a fake one. */
     public PhotoSync(Path directory, List<ProviderFactory> providers) {
+        this(ConfigLocations.fixed(directory), providers);
+    }
+
+    /** The standard set of backends, with a switchable storage location. */
+    public PhotoSync(ConfigLocations locations) {
+        this(locations, List.of(new ImmichProviderFactory()));
+    }
+
+    /** Takes the backend list explicitly so tests can run against a fake one. */
+    public PhotoSync(ConfigLocations locations, List<ProviderFactory> providers) {
+        this.locations = locations;
+        this.activeLocation = locations.resolve();
         this.catalog = new ProviderCatalog(providers);
-        this.config = new ConfigService(new ConfigStore(directory.resolve(CONFIG_FILE), catalog.preferred()));
+        this.config = new ConfigService(new ConfigStore(
+                locations.directory(activeLocation).resolve(CONFIG_FILE), catalog.preferred()));
         this.session = new ProviderSession(catalog);
-        // Reads and repairs the on-disk queue, so anything interrupted by the
-        // last quit is already pending again by the time uploads start.
-        this.queue = new UploadQueue(directory.resolve(QUEUE_FILE));
+        // The queue stays in the instance directory even when the settings file
+        // moves: its entries reference screenshot paths that are local to the
+        // instance, so a shared queue would point at the wrong files.
+        this.queue = new UploadQueue(locations.directory(ConfigLocation.INSTANCE).resolve(QUEUE_FILE));
         this.uploads = new UploadCoordinator(queue, session, () -> config.current().upload());
         this.browser = new TimelineBrowser(session);
         this.thumbnails = new ThumbnailLoader(session);
@@ -73,7 +96,9 @@ public final class PhotoSync implements AutoCloseable {
     /** Connects to the configured backend and starts draining the queue. */
     public PhotoSync start() {
         config.onChange(this::applyConnection);
+        config.onChange(this::applyLocation);
         applyConnection(config.current());
+        reconcileLocation();
         uploads.start();
         int resumed = queue.activeCount();
         if (resumed > 0) {
@@ -103,6 +128,61 @@ public final class PhotoSync implements AutoCloseable {
         uploads.wake();
     }
 
+    /** Where the settings file currently lives. */
+    public Path dataDirectory() {
+        return locations.directory(activeLocation);
+    }
+
+    /**
+     * Moves the settings file when the player switches storage location.
+     *
+     * <p>The upload queue is deliberately left in the instance directory; only
+     * the settings file follows the choice. The marker is written last, so a
+     * failure part-way leaves the old location authoritative for the next
+     * launch.
+     */
+    private void applyLocation(PhotoSyncConfig current) {
+        ConfigLocation next = current.location();
+        if (next == activeLocation) {
+            return;
+        }
+        try {
+            Path from = locations.directory(activeLocation);
+            Path to = locations.directory(next);
+            if (from.equals(to)) {
+                // A catalog with no real user directory (tests): nothing to move.
+                return;
+            }
+            Files.createDirectories(to);
+            moveFile(from.resolve(CONFIG_FILE), to.resolve(CONFIG_FILE));
+            config.relocate(to.resolve(CONFIG_FILE));
+            locations.writeMarker(next);
+            activeLocation = next;
+            log.info("PhotoSync settings moved to {}", to);
+        } catch (IOException e) {
+            log.error("Could not move PhotoSync settings to {}; keeping them in {}",
+                    locations.directory(next), locations.directory(activeLocation), e);
+            config.update(previous -> previous.toBuilder().location(activeLocation).build());
+        }
+    }
+
+    private static void moveFile(Path source, Path target) throws IOException {
+        if (Files.exists(source)) {
+            Files.move(source, target, StandardCopyOption.REPLACE_EXISTING);
+        }
+    }
+
+    /**
+     * Brings the settings file's own location field in line with the marker.
+     * They can only disagree when the file was hand-edited; the marker is the
+     * truth about where the file actually is.
+     */
+    private void reconcileLocation() {
+        if (config.current().location() != activeLocation) {
+            config.update(previous -> previous.toBuilder().location(activeLocation).build());
+        }
+    }
+
     @Override
     public void close() {
         thumbnails.close();

shared/core/src/main/java/dev/photosync/core/config/ConfigLocation.java

@@ -0,0 +1,11 @@
+package dev.photosync.core.config;
+
+/** Where PhotoSync keeps its settings file. */
+public enum ConfigLocation {
+
+    /** {@code config/photosync} inside the game directory -- the historical default, per instance. */
+    INSTANCE,
+
+    /** The OS-user-level directory, shared across Minecraft installs. */
+    USER
+}

shared/core/src/main/java/dev/photosync/core/config/ConfigLocations.java

@@ -0,0 +1,70 @@
+package dev.photosync.core.config;
+
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import dev.photosync.core.persistence.JsonFile;
+
+import java.io.IOException;
+import java.nio.file.Path;
+
+/**
+ * The two places PhotoSync's settings file may live, and the record of which
+ * one is active.
+ *
+ * <p>Which location is active cannot be stored inside the settings file itself,
+ * because the mod has to know where that file is before it can read it. So the
+ * choice is recorded in a small marker ({@code location.json}) that always
+ * lives in the instance directory: start-up reads the marker to pick a
+ * directory, and the settings screen rewrites it when the player switches. A
+ * missing or unreadable marker means the instance directory, which is also what
+ * every existing installation has, so nothing changes for them.
+ */
+public final class ConfigLocations {
+
+    private static final String MARKER_FILE = "location.json";
+
+    private final Path instanceDirectory;
+    private final Path userDirectory;
+    private final JsonFile marker;
+
+    public ConfigLocations(Path instanceDirectory, Path userDirectory) {
+        this.instanceDirectory = instanceDirectory;
+        this.userDirectory = userDirectory;
+        this.marker = new JsonFile(instanceDirectory.resolve(MARKER_FILE));
+    }
+
+    /** A catalog that offers no user directory, for tests and the plain constructor. */
+    public static ConfigLocations fixed(Path directory) {
+        return new ConfigLocations(directory, directory);
+    }
+
+    /** The active location: what the marker says, or the instance when it says nothing. */
+    public ConfigLocation resolve() {
+        JsonElement stored = marker.readTree().orElse(null);
+        if (stored == null || !stored.isJsonObject()) {
+            return ConfigLocation.INSTANCE;
+        }
+        JsonElement value = stored.getAsJsonObject().get("location");
+        if (value == null || !value.isJsonPrimitive()) {
+            return ConfigLocation.INSTANCE;
+        }
+        try {
+            return ConfigLocation.valueOf(value.getAsString());
+        } catch (IllegalArgumentException e) {
+            // A hand-edited marker names something that is not a location.
+            return ConfigLocation.INSTANCE;
+        }
+    }
+
+    /** The directory a location maps to. */
+    public Path directory(ConfigLocation location) {
+        return location == ConfigLocation.USER ? userDirectory : instanceDirectory;
+    }
+
+    /** Records the active location so the next launch looks in the right place. */
+    public void writeMarker(ConfigLocation location) throws IOException {
+        JsonObject written = new JsonObject();
+        written.addProperty("location", location.name());
+        marker.write(written);
+    }
+}

shared/core/src/main/java/dev/photosync/core/config/ConfigService.java

@@ -3,6 +3,7 @@ package dev.photosync.core.config;
 import lombok.extern.slf4j.Slf4j;
 
 import java.io.IOException;
+import java.nio.file.Path;
 import java.util.List;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.atomic.AtomicReference;
@@ -61,4 +62,9 @@ public final class ConfigService {
             log.error("Could not write {}", store.path(), e);
         }
     }
+
+    /** Points the store at a new file, after the settings file has been moved there. */
+    public void relocate(Path path) {
+        store.relocate(path);
+    }
 }

shared/core/src/main/java/dev/photosync/core/config/ConfigStore.java

@@ -25,7 +25,7 @@ import java.util.Optional;
 @Slf4j
 public final class ConfigStore {
 
-    private final JsonFile file;
+    private JsonFile file;
     private final ProviderId fallbackProvider;
 
     public ConfigStore(Path path, ProviderId fallbackProvider) {
@@ -37,6 +37,11 @@ public final class ConfigStore {
         return file.path();
     }
 
+    /** Points the store at a new file, after the settings file has been moved there. */
+    public void relocate(Path path) {
+        this.file = new JsonFile(path);
+    }
+
     /** Never throws: a broken config falls back to defaults rather than blocking start-up. */
     public PhotoSyncConfig load() {
         PhotoSyncConfig defaults = PhotoSyncConfig.defaults(fallbackProvider);

shared/core/src/main/java/dev/photosync/core/config/PhotoSyncConfig.java

@@ -21,7 +21,8 @@ public record PhotoSyncConfig(
         UploadSettings upload,
         AutoCaptureSettings autoCapture,
         NotificationSettings notifications,
-        BrowserSettings browser) {
+        BrowserSettings browser,
+        ConfigLocation location) {
 
     public static PhotoSyncConfig defaults(ProviderId provider) {
         return PhotoSyncConfig.builder()
@@ -32,6 +33,7 @@ public record PhotoSyncConfig(
                 .autoCapture(AutoCaptureSettings.defaults())
                 .notifications(NotificationSettings.defaults())
                 .browser(BrowserSettings.defaults())
+                .location(ConfigLocation.INSTANCE)
                 .build();
     }
 
@@ -49,6 +51,7 @@ public record PhotoSyncConfig(
                 .autoCapture((autoCapture == null ? AutoCaptureSettings.defaults() : autoCapture).normalized())
                 .notifications((notifications == null ? NotificationSettings.defaults() : notifications).normalized())
                 .browser((browser == null ? BrowserSettings.defaults() : browser).normalized())
+                .location(location == null ? ConfigLocation.INSTANCE : location)
                 .build();
     }
 

shared/core/src/test/java/dev/photosync/core/config/ConfigLocationsTest.java

@@ -0,0 +1,62 @@
+package dev.photosync.core.config;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+/** The marker that decides where the settings file lives. */
+class ConfigLocationsTest {
+
+    @TempDir
+    Path temp;
+
+    @Test
+    void resolvesTheInstanceDirectoryWhenThereIsNoMarker() {
+        ConfigLocations locations = new ConfigLocations(temp.resolve("instance"), temp.resolve("user"));
+        assertEquals(ConfigLocation.INSTANCE, locations.resolve());
+        assertEquals(temp.resolve("instance"), locations.directory(ConfigLocation.INSTANCE));
+        assertEquals(temp.resolve("user"), locations.directory(ConfigLocation.USER));
+    }
+
+    @Test
+    void remembersTheChoiceAcrossInstances() throws Exception {
+        Path instance = temp.resolve("instance");
+        ConfigLocations locations = new ConfigLocations(instance, temp.resolve("user"));
+        locations.writeMarker(ConfigLocation.USER);
+
+        // A fresh PhotoSync reads the same marker and arrives at the same answer.
+        ConfigLocations reopened = new ConfigLocations(instance, temp.resolve("user"));
+        assertEquals(ConfigLocation.USER, reopened.resolve());
+    }
+
+    @Test
+    void fallsBackToTheInstanceDirectoryForAGarbageMarker() throws Exception {
+        Path instance = temp.resolve("instance");
+        Files.createDirectories(instance);
+        Files.writeString(instance.resolve("location.json"), "not json");
+
+        ConfigLocations locations = new ConfigLocations(instance, temp.resolve("user"));
+        assertEquals(ConfigLocation.INSTANCE, locations.resolve());
+    }
+
+    @Test
+    void fallsBackToTheInstanceDirectoryForAnUnknownLocation() throws Exception {
+        Path instance = temp.resolve("instance");
+        Files.createDirectories(instance);
+        Files.writeString(instance.resolve("location.json"), "{\"location\":\"elsewhere\"}");
+
+        ConfigLocations locations = new ConfigLocations(instance, temp.resolve("user"));
+        assertEquals(ConfigLocation.INSTANCE, locations.resolve());
+    }
+
+    @Test
+    void fixedCatalogTreatsTheUserDirectoryAsTheInstanceDirectory() {
+        ConfigLocations locations = ConfigLocations.fixed(temp.resolve("dir"));
+        assertEquals(ConfigLocation.INSTANCE, locations.resolve());
+        assertEquals(locations.directory(ConfigLocation.INSTANCE), locations.directory(ConfigLocation.USER));
+    }
+}

shared/core/src/test/java/dev/photosync/core/config/PhotoSyncRelocationTest.java

@@ -0,0 +1,105 @@
+package dev.photosync.core.config;
+
+import dev.photosync.core.PhotoSync;
+import dev.photosync.core.capture.CaptureOrigin;
+import dev.photosync.core.capture.CapturedScreenshot;
+import dev.photosync.core.provider.AlbumRef;
+import dev.photosync.core.provider.immich.ImmichProviderFactory;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/** Switching the storage location really moves the settings file, and nothing else. */
+class PhotoSyncRelocationTest {
+
+    @TempDir
+    Path temp;
+
+    private ConfigLocations locations() {
+        return new ConfigLocations(temp.resolve("instance"), temp.resolve("user"));
+    }
+
+    private PhotoSync started(ConfigLocations locations) {
+        PhotoSync core = new PhotoSync(locations, List.of(new ImmichProviderFactory()));
+        core.start();
+        return core;
+    }
+
+    @Test
+    void movesSettingsFileAndRemembersTheChoice() throws Exception {
+        Path instance = temp.resolve("instance");
+        Path user = temp.resolve("user");
+        ConfigLocations locations = locations();
+
+        PhotoSync core = started(locations);
+        core.config().update(current -> current.toBuilder().albumId("first").build());
+        assertTrue(Files.exists(instance.resolve("photosync.json")));
+
+        core.config().update(current -> current.toBuilder().location(ConfigLocation.USER).build());
+
+        // The file followed the setting, and the marker says where it went.
+        assertFalse(Files.exists(instance.resolve("photosync.json")));
+        assertTrue(Files.exists(user.resolve("photosync.json")));
+        assertEquals(ConfigLocation.USER, locations.resolve());
+        assertEquals(ConfigLocation.USER, core.config().current().location());
+        assertEquals(user, core.dataDirectory());
+
+        // Later saves land in the new place.
+        core.config().update(current -> current.toBuilder().albumId("second").build());
+        assertTrue(Files.readString(user.resolve("photosync.json")).contains("\"second\""));
+
+        core.close();
+
+        // A fresh PhotoSync resolves the marker and reads the moved file.
+        PhotoSync reopened = started(locations);
+        assertEquals(ConfigLocation.USER, reopened.config().current().location());
+        assertEquals("second", reopened.config().current().albumId());
+        reopened.close();
+    }
+
+    @Test
+    void switchesBackToTheInstanceDirectory() throws Exception {
+        Path instance = temp.resolve("instance");
+        Path user = temp.resolve("user");
+        ConfigLocations locations = locations();
+
+        PhotoSync core = started(locations);
+        core.config().update(current -> current.toBuilder().location(ConfigLocation.USER).build());
+        assertTrue(Files.exists(user.resolve("photosync.json")));
+
+        core.config().update(current -> current.toBuilder().location(ConfigLocation.INSTANCE).build());
+
+        assertTrue(Files.exists(instance.resolve("photosync.json")));
+        assertFalse(Files.exists(user.resolve("photosync.json")));
+        assertEquals(ConfigLocation.INSTANCE, locations.resolve());
+        assertEquals(instance, core.dataDirectory());
+        core.close();
+    }
+
+    @Test
+    void leavesTheUploadQueueInTheInstanceDirectory() throws Exception {
+        Path instance = temp.resolve("instance");
+        Path user = temp.resolve("user");
+        Path shot = temp.resolve("screenshot.png");
+        Files.writeString(shot, "fake png");
+        ConfigLocations locations = locations();
+
+        PhotoSync core = started(locations);
+        core.queue().enqueue(CapturedScreenshot.of(shot, CaptureOrigin.MANUAL), AlbumRef.library(), "test");
+        assertTrue(Files.exists(instance.resolve("uploads.json")));
+
+        core.config().update(current -> current.toBuilder().location(ConfigLocation.USER).build());
+
+        // The queue references instance-local screenshot paths, so it stays put.
+        assertTrue(Files.exists(instance.resolve("uploads.json")));
+        assertFalse(Files.exists(user.resolve("uploads.json")));
+        core.close();
+    }
+}

shared/mc-api/src/main/java/dev/photosync/mcapi/GameContext.java

@@ -26,9 +26,23 @@ public interface GameContext {
      */
     Optional<CameraPose> cameraPose();
 
-    /** {@code .minecraft/config}, where PhotoSync keeps its settings and upload queue. */
+    /**
+     * The game-instance config directory (the {@code config/photosync} folder
+     * inside the game directory), where PhotoSync historically keeps its
+     * settings and upload queue. The settings file can be moved to
+     * {@link #userDataDirectory()} from the settings screen; the upload queue
+     * always stays here.
+     */
     Path configDirectory();
 
+    /**
+     * The OS-user-level directory offered as the alternative home for the
+     * settings file: {@code ~/.config/photosyncmod} on Linux and macOS,
+     * {@code %APPDATA%\photosyncmod} on Windows. Only used once the player
+     * chooses it; {@link #configDirectory()} stays the default.
+     */
+    Path userDataDirectory();
+
     /**
      * Runs a task on the render thread, or immediately if already on it.
      *

shared/ui/src/main/java/dev/photosync/ui/screen/SettingsScreen.java

@@ -2,6 +2,7 @@ package dev.photosync.ui.screen;
 
 import dev.photosync.core.config.AutoCaptureSettings;
 import dev.photosync.core.config.BrowserSettings;
+import dev.photosync.core.config.ConfigLocation;
 import dev.photosync.core.config.NotificationSettings;
 import dev.photosync.core.config.PhotoSyncConfig;
 import dev.photosync.core.config.UploadSettings;
@@ -122,6 +123,7 @@ public final class SettingsScreen extends PhotoSyncScreen {
         rows.clear();
         measuredLineHeight = -1;
 
+        buildStorage();
         buildConnection();
         buildUpload();
         buildAutoCapture();
@@ -129,6 +131,24 @@ public final class SettingsScreen extends PhotoSyncScreen {
         buildBrowser();
     }
 
+    private void buildStorage() {
+        heading("photosync.settings.section.storage");
+        Toggle outsideGame = new Toggle(chrome, chrome.translate("photosync.settings.user_config_location"),
+                () -> draft().location() == ConfigLocation.USER,
+                value -> edit(config -> config.toBuilder()
+                        .location(value ? ConfigLocation.USER : ConfigLocation.INSTANCE)
+                        .build()));
+        outsideGame.describedAs(chrome.translate("photosync.settings.user_config_location.detail",
+                ui.core().locations().directory(ConfigLocation.USER)));
+        rows.add(new Row("photosync.settings.user_config_location", content.add(outsideGame), true));
+        control("photosync.settings.config_folder",
+                new Button(chrome, chrome.translate("photosync.settings.show_folder"), this::revealConfigFolder));
+    }
+
+    private void revealConfigFolder() {
+        ui.game().reveal(ui.core().dataDirectory());
+    }
+
     private void buildConnection() {
         heading("photosync.settings.section.connection");