Reload-Safe Configs

Reload-Safe Configs

DaisyConfig has the same runtime safety rule across every handle layer:

• current always exposes the last good typed value
• a successful reload replaces it
• a failed reload keeps the previous good value live

Simple handles

DaisyConfigHandle<T> is the simple unmanaged path:

when (val result = profileConfig.reload()) {
    is DaisyReloadResult.Success -> logger.info("Reloaded.")
    is DaisyReloadResult.Failure -> logger.warning(result.errors.joinToString { "${it.path}: ${it.message}" })
}

That protects a single file without adding versioning or migration semantics.

Managed handles

DaisyManagedConfigHandle<T> keeps the same last-good guarantee, but adds:

• config_version
• default-file creation
• missing-key merge
• ordered migrations
• migration reports

when (val result = settingsHandle.migrate()) {
    is DaisyManagedReloadResult.Success -> {
        logger.info("Version ${result.report.versionBefore ?: 1} -> ${result.report.versionAfter}")
    }
    is DaisyManagedReloadResult.Failure -> {
        logger.warning(result.errors.joinToString { "${it.path}: ${it.message}" })
    }
}

Managed module bundles

DaisyModuleHandle<S> applies the same safety rule to:

• typed settings
• optional lang
• one module text source

That means settings.yml and lang.yml move together as one runtime unit.

when (val result = spawnModule.migrate()) {
    is DaisyManagedBundleReloadResult.Success -> logger.info("Spawn module migrated.")
    is DaisyManagedBundleReloadResult.Failure -> logger.warning(result.errors.joinToString { "${it.path}: ${it.message}" })
}

Broken-file scenario

If a live file becomes invalid during reload:

• decode fails
• errors are returned
• the previous good typed value stays active

That rule is the same for:

• DaisyConfigHandle<T>
• DaisyManagedConfigHandle<T>
• DaisyModuleHandle<S>

Because a typo in YAML should not switch runtime state to a half-decoded config.