add-mod-loader

name	add-mod-loader
description	Add support for a new Minecraft mod loader (like a new Forge fork or new loader project). Use when implementing a new loader backend, adding loader version fetching, or wiring a loader into the launch pipeline.

Adding a New Mod Loader

Follow this sequence when adding support for a new mod loader.

1. Add to LoaderType Enum

File: src-tauri/src/models/instance.rs

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "lowercase")]
pub enum LoaderType {
    Vanilla,
    Fabric,
    Forge,
    Neoforge,
    Quilt,
    NewLoader,  // ← add here
}

2. Create the Loader Service

File: src-tauri/src/services/new_loader.rs

Implement: get_loader_versions, get_game_versions, ensure_loader_libraries.

Rules: use shared HTTP client, cache metadata in paths::meta_dir(), return main class + library paths + JVM args + game args.

3. Register in Services Module

File: src-tauri/src/services/mod.rs — add pub mod new_loader;

4. Add to Launch Pipeline

File: src-tauri/src/services/launch.rs — add match arm in the loader type block.

5. Add Meta Commands

File: src-tauri/src/commands/meta.rs — add version/game-version fetch commands. Register in lib.rs.

6. Add TypeScript Wrappers

File: src/ipc/commands.ts — typed wrappers for the new meta commands.

7. Update Create Instance UI

File: src/modals/CreateCustom.tsx — add loader to selection, fetch versions.

8. Update Mod Search

Ensure loader name matches what the mod search APIs expect.

Verification

• Can create an instance with the new loader
• Loader libraries download correctly
• Game launches with correct main class
• Mods searchable and installable
• Existing loaders still work