Release v26.0 Alpha 3 · StarsailsClover/MCDebugLauncher

What's Changed

Fabric classpath / library download

Loader libraries (intermediary, ASM 9.7.x, fabric-loader itself) are now downloaded at launch time when not already cached. Previously only path resolution was attempted, causing silent skips and resulting in ClassNotFoundException on startup and Fabric's duplicate-library rejection.
Added support for Fabric/Quilt-style library entries that carry only a Maven repository base URL rather than a full per-artifact download record.
Fabric intermediary mappings are now written to version.json and downloaded explicitly during mdl create, fixing the method_30611 crash observed with any mod including fabric-api alone.

NeoForge mainClass inheritance

VersionJson.mainClass is now treated as optional. Installer-produced JSONs that omit the field no longer cause a deserialization panic; the launcher falls back to the base Minecraft version JSON.

Agent server

Fixed LaunchOptions::default() call in the agent HTTP executor after the struct gained new fields in Alpha 2.

Game window title

The Minecraft window title is set to MDL: <instance> [mod1, mod2, ...] via the --title argument (Minecraft 1.14+), making it easy to identify which test session a game window belongs to.

Asset mirror support

Set the environment variable MDL_ASSETS_MIRROR to a CDN base URL (e.g. https://bmclapi2.bangbang93.com) to override the default Mojang asset server. Useful in regions where resources.download.minecraft.net is unreliable.

mdl agent single-instance lock

A second mdl agent invocation now exits immediately with a clear message showing the existing process PID and interface address, instead of failing with a raw port-binding error.

Fabric API auto-install

mdl create --loader fabric now automatically downloads and installs the latest compatible Fabric API from Modrinth into the instance mods/ directory. Non-fatal: logs a warning if the download fails.

Full Changelog: v26.0-alpha.2...v26.0-alpha.3