handleWatchEvent(config: Config,extensions: string[],event: string,filePath: string,onEventFunc: (event: string,file: string) => unknown,onFinishFunc: ((path: string,event: string) => void) | null | undefined): void
Routes a file-system event to fsTree mutation and optional rebuild trigger.
unlinkDir bypasses the extension filter so deleted directories always clean up fsTree.
config: Config