Function layer_config

crates/core/src/plugin.rs:909–924

Layers `right` (higher precedence) onto `left` in place. Objects merge recursively and arrays/scalars are replaced by `right`, except the top-level `components` array, whose entries pair by `kind` in order of appearance so multi-instance kinds are not collapsed. Internal helper shared by plugin initialization and `plugins.toml` discovery.

(left: &mut Json, right: Json)

/// multi-instance kinds are not collapsed. Internal helper shared by plugin
/// initialization and `plugins.toml` discovery.
fn layer_config(left: &mut Json, right: Json) {
    match (left, right) {
        (Json::Object(left), Json::Object(right)) => {
            for (key, value) in right {
                match (key.as_str(), left.get_mut(&key)) {
                    ("components", Some(existing)) => merge_plugin_components(existing, value),
                    (_, Some(existing)) => merge_json_value(existing, value),
                    (_, _) => {
                        left.insert(key, value);
                    }
                }
            }
        }
        (left, right) => *left = right,
    }
}

/// Merges `right` components into `left` by `kind`, pairing repeated kinds positionally.
fn merge_plugin_components(left: &mut Json, right: Json) {