Why should I check file permissions before starting a Kaspa node on Linux?

On Linux, the files that make up your Kaspa node database must be owned by the same user account that runs the kaspad service, or the node will fail to start. File permissions control which user can read and write each file on the system — if the database files were copied or synced by a different user (for example, during a fast-sync from another node), the service account may not have access to them. Checking ownership before you start kaspad saves you from a confusing startup failure that has nothing to do with the node software itself.