metadata.json Schema

Full Schema

{
  "name": "my_module",
  "version": "1.0.0",
  "description": "What this module does",
  "author": "Author Name",
  "type": "core",
  "interface": "universal",
  "category": "general",
  "main": "my_module_plugin",
  "dependencies": [],
  "include": [],
  "capabilities": [],

  "nix": {
    "packages": {
      "build": [],
      "runtime": []
    },
    "external_libraries": [],
    "cmake": {
      "find_packages": [],
      "extra_sources": [],
      "extra_include_dirs": [],
      "extra_link_libraries": []
    }
  }
}

Required Fields

Field	Type	Description
`name`	string	Module identifier. Must match binary prefix: `my_module` -> `my_module_plugin.so`
`version`	string	Semantic version (`"1.0.0"`)
`type`	string	`"core"` for modules, `"ui_qml"` for UI apps
`main`	string	Plugin binary name without extension: `"my_module_plugin"` (optional for pure QML UI apps)

Universal Module Fields

Field	Value	Description
`interface`	`"universal"`	Signals that this module uses pure C++ impl + code generation

When "interface": "universal" is set, the build system expects logos-cpp-generator --from-header to run in preConfigure and produce Qt glue files.

Dependencies

"dependencies": ["storage_module", "crypto_module"]

Values must match the name field in the dependency module's own metadata.json. The runtime loads dependencies before the module.

Flake input attribute names should also match the dependency module names when possible. Example: if you depend on storage_module from repo logos-storage-module, the flake input should be named logos-storage-module.

External Libraries

"nix": {
  "external_libraries": [
    {
      "name": "mylib",
      "build_command": "make static-library",
      "output_pattern": "build/libmylib.*"
    }
  ]
}

For Go libraries, add "go_build": true. The external library source is provided as a non-flake input in flake.nix and mapped via externalLibInputs.

Nix Packages

"nix": {
  "packages": {
    "build": ["pkg-config"],
    "runtime": ["nlohmann_json", "openssl"]
  }
}

build packages are available during compilation only. runtime packages are linked and available at runtime.

CMake Configuration

"nix": {
  "cmake": {
    "find_packages": ["Threads", "OpenSSL"],
    "extra_sources": ["src/helper.cpp"],
    "extra_include_dirs": ["include"],
    "extra_link_libraries": ["Threads::Threads"]
  }
}

These values are passed to CMake by the logos_module() macro. They supplement, not replace, the automatic SDK and Qt dependencies.

UI App Specific Fields

{
  "type": "ui_qml",
  "view": "Main.qml",
  "icon": "icon.png",
  "category": "tools"
}

Field	Type	Description
`view`	string	Required for `ui_qml`. Path to QML entry point (e.g., `"Main.qml"` or `"qml/Main.qml"`)
`main`	string	Optional. If present, indicates a C++ backend plugin (e.g., `"my_app_plugin"`). If absent, the app is pure QML

Pure QML apps have no "main" field — no C++ compilation occurs. QML + backend apps have both "main" (C++ plugin) and "view" (QML entry point).

UI apps do not use "interface": "universal" — they use mkLogosQmlModule in their flake.nix.

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