a .kern file is a zip archive containing manifest.json (required), an optional dist/index.js esm ui bundle, an optional dist/index.css, and any other assets the bundle references.

the manifest declares metadata, a dynamic config form, lifecycle commands, starter files, and ui tabs.

jsonc
{
  "id": "web_api",
  "displayName": "Web API Server",
  "version": "1.0.0",
  "author": "kern/official",
  "description": "Run a Node.js/Express web API with env-based config, health checks, and pm2 or nodemon for hot reload.",
  "uiEntry": "dist/index.js",

  "configSchema": [
    { "key": "port", "label": "Port", "type": "text", "default": "3000" },
    { "key": "log_level", "label": "Log Level", "type": "select",
      "options": ["debug","info","warn","error"], "default": "info" }
  ],

  "lifecycle": {
    "start": { "command": "node", "args": ["{{userOverrides.entry}}"] },
    "start.nodemon": { "command": "nodemon", "args": ["{{userOverrides.entry}}"], "useShell": true }
  },

  "scaffold": {
    "env": { "path": ".env", "content": "PORT={{userOverrides.port}}\nLOG_LEVEL={{userOverrides.log_level}}\n" },
    "readme": { "path": "README.md", "content": "Web API ({{userOverrides.port}})…" }
  },

  "tabs": [ { "id": "setup", "label": "Setup" }, { "id": "logs", "label": "Logs" } ]
}

| field | type | required | notes | |---|---|---|---| | id | string | yes | unique, lowercase, underscores. the registry key. | | displayName | string | yes | human name. | | version | string | yes | semver. | | author | string | yes | kern/sample, kern/official, or a github handle. | | description | string | yes | one-liner for cards/detail. | | uiEntry | path | no | dist/index.js — the esm bundle exposing mount(hostApi). | | configSchema | field[] | no | the dynamic config form (see config-schema). | | lifecycle | object | no | named lifecycle steps (see lifecycle). | | scaffold | object | no | starter files written into a fresh instance (see scaffold). | | tabs | tab[] | no | declarative tabs the plugin registers in the detail view. |