Pack authoring

Pastel consumes the standard Modrinth .mrpack format. A pack that accurately describes its dedicated-server files does not need Pastel-specific metadata.

Pastel applies indexed server files, then shared overrides, then server overrides. A later file replaces an earlier file at the same path. Client overrides are ignored. — Override order determines which file the dedicated server receives.

Archive structure

example-pack.mrpack
├── modrinth.index.json
├── overrides/
├── server-overrides/
└── client-overrides/

Use formatVersion: 1, game: "minecraft", a name, and a versionId. Set dependencies.minecraft; a modded pack should also declare exactly one loader. Each downloadable file needs at least one URL and supported hash. Pastel prefers SHA-512, followed by SHA-256 and SHA-1. When fileSize is greater than zero, the downloaded size must also match.

Paths must be clean, relative, slash-separated paths. Pastel rejects absolute paths, traversal components, backslashes, and ambiguous path components.

Dedicated-server files

Pastel installs a file unless env.server is unsupported.

`env.server`	Installed
`required`	Yes
`optional`	Yes; Pastel does not present a file picker.
Omitted	Yes
`unsupported`	No

Mark client-only mods as unsupported. A client-only jar marked required or optional commonly causes dedicated-server startup failures.

Overrides

Pastel applies overrides/ first and server-overrides/ second. A server override replaces a shared override at the same path. client-overrides/ is ignored.

Jars embedded under either override layer's mods/ directory become part of the managed mod set. Prefer normal indexed files when an artifact has a stable URL; the index records its expected size and hashes without making the pack archive larger.

Keep server data out of packs

Pastel refuses indexed files under world/, but does not apply that check to overrides or custom world paths. Overrides replace existing files on refresh. Keep worlds, secrets, operator lists, and other server-owner data out of them.

Loader support

Loader	Pack dependency	Behavior
Fabric	`fabric-loader`	Downloads a launcher for the declared Minecraft and loader versions.
NeoForge	`neoforge`	Uses an existing server launch tree or runs the official installer.
Forge	`forge`	Uses an existing server launch tree or runs the official installer.
Quilt	`quilt-loader`	Requires a prepared server launch tree, such as `quilt-server-launch.jar`; automatic installation is not available.
Vanilla	None	Requires a pack-provided `server.jar`.

For modded packs, declare minecraft alongside exactly one loader dependency. Vanilla packs only need minecraft. For Forge, Pastel combines a loader version without a Minecraft prefix with the declared Minecraft version when resolving the installer artifact.

Forge and NeoForge use the generated unix_args.txt or win_args.txt plus user_jvm_args.txt. In Pastel 0.1.7, an existing launch tree may be reused even after changing the dependency version. Test loader and Minecraft upgrades in a fresh server directory. Quilt and vanilla packs must include any libraries needed by their supplied launcher, not just its jar.

Distribution

Server owners can install the same pack through:

a Modrinth slug or project page;
a direct HTTPS .mrpack URL;
a local archive or unpacked directory; or
a Maven coordinate and explicitly configured repository.

Maven distribution uses the normal group/artifact/version/artifact-version.mrpack layout. Provide maven-metadata.xml for latest-version resolution and interactive updates. Pastel fetches .mrpack artifacts directly and does not require a POM. It does not accept a JSON, jar, or .pastel fallback for a Maven pack. Match the index's versionId to the Maven version so installed-version reporting and updates agree.

Author checklist

Test the .mrpack in a new, empty directory.
Mark every client-only file as unsupported on the server.
Include strong hashes and accurate sizes.
Test the exact Minecraft and loader pair declared by the index.
Keep worlds, credentials, and server-owner data out of overrides.
Preview changes with pastel refresh -dry-run.
Stop the server before installing, refreshing, or updating a pack.