Mixin basics: YAML mode vs JavaScript mode

Mixin merges your customizations into the active profile at load time (Settings → Profile Mixin). It has two authoring modes with very different behavior:

YAML mode: declarative override

mixin:
  dns:
    enable: true
    enhanced-mode: fake-ip
  log-level: debug

Whatever field you write replaces the same-named field wholesale. Great for DNS or log-level, where swapping the whole block is fine; wrong for rules — you almost certainly want "append", not "only these remain".

JavaScript mode: programmable merge

module.exports.parse = async (raw, { yaml }) => {
  const config = yaml.parse(raw);
  // insert two rules ahead of the originals
  config.rules = [
    "DOMAIN-SUFFIX,mybank.com,DIRECT",
    "DOMAIN-KEYWORD,ads,REJECT",
    ...config.rules,
  ];
  return yaml.stringify(config);
};

JS mode hands you the whole config object — insert rules, filter nodes by name, batch-edit node properties, anything.

Choosing

Only touching DNS / log level → YAML suffices. Anything involving rules or proxies lists → go straight to JS. Remember to flip the Mixin enable switch and re-select the profile to reload.