Validation and Lifecycle Hooks

Implement ConfigExtension on the config class to participate in the load/save/validate lifecycle:

@Config(name = "mymod")
public final class MyModConfig implements ConfigExtension {

    public int hudScale = 2;
    public String worldPreset = "default";

    @Override
    public void afterLoad() {
        // Fix up values after loading — clamp ranges, derive computed fields, etc.
        hudScale = Math.max(1, Math.min(8, hudScale));
    }

    @Override
    public void beforeSave() {
        // Normalize values before writing to disk, if needed.
        // Most configs leave this empty.
    }

    @Override
    public void validate(List<Violation> violations) {
        // Report constraint violations. Must be side-effect free.
        if (hudScale < 1 || hudScale > 8) {
            violations.add(Violation.of("hud-scale.range", "hudScale must be between 1 and 8, was " + hudScale));
        }
    }
}

Hook order and contract:

• afterLoad runs after deserialization, before validation. Use it to normalize or clamp values.
• validate runs after afterLoad, on every load and before every update is published. It must be side-effect free — correct values in afterLoad, report them in validate.
• beforeSave runs immediately before serialization.

Handling validation failures:

Under FALLBACK update policy, violations come back on the UpdateResult:

UpdateResult result = holder.updateAndSave(config -> config.hudScale = 99);
if (!result.accepted()) {
    result.violations().forEach(v -> LOGGER.warn("{}: {}", v.id(), v.message()));
}

Under STRICT, the same violations ride on EasyConfigException.violations().

Validation on load: if the file on disk contains values that fail validate, the behavior depends on readFailurePolicy. Under FALLBACK, the file is backed up and defaults are written. Under STRICT, the load throws.