Manifest - Lode Studio

Two files describe an expansion: meta.json is who it is, config.json is how to run it. Neither contains code, and both are read before anything of yours runs. Every problem in them is reported at once, naming the file and the field, so you fix the list rather than one error per reload:

meta.json: "id" must be lowercase a-z, 0-9 and _, got "My-Exp"
meta.json: "sdkVersion" is required, e.g. "^2.0.0"
config.json: start file "src/main.ts" does not exist

meta.json

meta.json

{
  "id": "my_expansion",
  "name": "My Expansion",
  "version": "1.0.0",
  "description": "Does cool things",
  "author": "Developer",
  "apiKey": "nmk_...",
  "sdkVersion": "^2.0.0",
  "permissions": ["project:read"],
  "dependencies": {}
}

Field	Required	Rules
`id`	yes	Lowercase `a-z`, `0-9` and `_`, at most 64 characters. Your expansion’s only identity: the folder name is ignored, and two installed expansions cannot share one.
`name`	yes	Shown in the app.
`version`	yes	Semantic version, `1.0.0`.
`apiKey`	yes	Your NMCrate secret for this `id`. See Publishing.
`sdkVersion`	yes	The SDK range you built against, e.g. `^2.0.0`. Ranges understood: `*`, `2`, `2.x`, `1.2.3`, `^1.2.3`, `~1.2.3`, comparators like `>=2.0.0 <3.0.0`, and `\|\|` between them.
`description`, `author`	no	Strings, shown in the app and used by NMCrate.
`permissions`	no	From the catalog in Permissions. Anything else is an error.
`dependencies`	no	Must be `{}` for now. Reserved for the NMCrate library system; your own libraries need no entry here.

Unknown keys are kept out of the way with a warning rather than failing the load. "type": "library" is reserved and currently refused.

id and version, in practice

The id appears in the routes of your pages (custom/my_expansion.home) and prefixes everything you register, so two expansions can both have a home page.
Changing id after release means NMCrate sees a different expansion, and per-project state saved under the old id is no longer read.
version is what the store shows and what an update compares against.

config.json

config.json

{ "start": "src/index.ts" }

Field	Required	Rules
`start`	no	The file the app runs first, relative to the expansion folder. Defaults to `src/index.ts`, then `src/index.js`. It must exist and be inside the folder.

A missing config.json is accepted with a warning and the defaults. These keys are reserved, accepted with a warning and otherwise ignored today: settings, locales, background, build, main.

Compatibility

sdkVersion is checked against the SDK the app provides, 2.0.0:

satisfied: loads normally
not satisfied: does not load, and the Expansions page says

Built for SDK ^3.0.0, but this app provides SDK 2.0.0. Update the app or the expansion.

Prereleases only match a range that mentions one, as in npm.