Fix vanilla instance creation issue by implementing proper mod loader profile management

[Copilot]

This PR addresses the critical issue where ChaiLauncher was creating vanilla instances instead of properly modded ones when installing modpacks or creating modded instances. The root cause was that the system created mod loader profiles but instances still used vanilla version identifiers when launching.

Problem

When users installed modpacks or created modded instances, ChaiLauncher would:

• Install mod loaders and create proper profiles (e.g., fabric-loader-0.15.7-1.20.1)
• But register instances with vanilla version identifiers (e.g., 1.20.1)
• Result in instances that appeared vanilla when launching, even though mod loaders were installed

Solution

Fixed Profile Management

• install_mod_loader() now returns the created profile name instead of void
• Instance metadata uses the mod loader profile as the version identifier
• Launch system reads actual instance metadata to detect modded instances properly

Enhanced Modpack Installation

// Now properly detects game version and mod loader from modpack metadata
let (game_version, mod_loader) = get_modpack_details(&modpack_id, &version_id, &platform).await;

// Uses the actual mod loader profile name as instance version
let instance_version = get_modpack_profile_name(&modpack_id, &version_id, &platform).await;

Improved Launch Detection

• launch_instance command now reads from storage to get actual instance metadata
• Properly detects modded instances and logs launch type
• Fixed hardcoded is_modded: false that was overriding correct detection

Added Diagnostic Tools

• diagnose_instances command to analyze instance status and identify issues
• fix_vanilla_instances command to automatically repair incorrectly marked instances
• Both commands check mod directories, profiles, and metadata consistency

Before vs After

Before: Instance uses version "1.20.1" → Launcher loads vanilla profile → Mods don't work
After: Instance uses version "fabric-loader-0.15.7-1.20.1" → Launcher loads modded profile → Mods work correctly

This ensures that modpacks and modded instances are truly functional with working mod loaders, not just directory structures with vanilla profiles.

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[tristanpoland]

@copilot we have an issue where we never actually install the mods into the instance folder we need to ensure src-tauri\src\libium_integration is being used to properly install the mods and overrides as well as the mod loader rn it creates vanilla instances

[Copilot]

@copilot we have an issue where we never actually install the mods into the instance folder we need to ensure src-tauri\src\libium_integration is being used to properly install the mods and overrid...

I've implemented a comprehensive mod loader installation system that addresses the issue you identified. The problem was that ChaiLauncher was creating vanilla instances even when installing modpacks because it wasn't actually installing the underlying mod loaders (Fabric, Forge, etc.).

Key Changes (commit 77174ba):

New Mod Loader Installation System:

• Added install_mod_loader() function that downloads and installs mod loader profiles and libraries
• Supports Fabric, Quilt, Forge, and NeoForge with proper API integration
• Downloads mod loader profiles and extracts libraries to the correct directories

Enhanced Instance Creation:

• create_modded_instance now actually installs the mod loader during instance creation
• Added create_instance_with_loader for creating instances with optional mod loader support
• Added install_instance_mod_loader to upgrade existing vanilla instances to modded ones

Improved Modpack Installation:

• Modpack installation now properly installs the underlying mod loader first
• Enhanced Modrinth modpack support with proper .mrpack extraction
• Extracts mods and overrides to correct directories
• Detects mod loader and game version from modpack metadata

The src-tauri\src\libium_integration module is now properly connected to instance creation and will ensure mods and mod loaders are correctly installed rather than just creating empty directory structures.

[tristanpoland]

@copilot The instance is still just entirely vanilla still look into the code deeply to understand how each install type works and fix it all

[Copilot]

@copilot The instance is still just entirely vanilla still look into the code deeply to understand how each install type works and fix it all

I've identified and fixed the core issue causing vanilla instances. The problem was that mod loader installation was creating profiles but instances were still using vanilla version identifiers.

Root Cause Fixed (commit e6983e9):

Profile Management:

• Mod loader installation now returns the actual profile name (e.g., fabric-loader-0.15.7-1.20.1)
• Instance metadata uses mod loader profiles as version instead of vanilla versions
• Launch system properly detects modded instances from storage

Modpack Installation Enhanced:

• Fixed hardcoded game versions - now detects from modpack metadata
• Added mod extraction logging to show what's being installed
• Returns actual mod count instead of 0

Diagnostic Tools Added:

• diagnose_instances command to analyze instance status
• fix_vanilla_instances command to automatically fix incorrectly marked instances

The instances should now be properly modded with working mod loaders. For existing instances, you can use the diagnostic commands to identify and fix any that are still incorrectly marked as vanilla.

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