Inconsistent hostname resolution between /etc/hostname and /etc/hosts causes production failures in Arch Linux

Systemd-hostnamed resolves the system hostname by first reading the contents of /etc/hostname and then consulting /etc/hosts, a design intended to support dynamic host configuration. In local installations where both files contain matching entries, hostname services operate as expected, but in production or containerized setups the /etc/hosts file may be absent or differ, causing systemd-hostnamed to fall back to a static name and breaking service discovery. The challenge is to define a reliable method that guarantees the hostname used by systemd-hostnamed matches the intended identity regardless of environment differences.

How should the /etc/hostname and /etc/hosts entries be synchronized to ensure consistent hostname resolution across local and production systems? Which configuration practices prevent systemd-hostnamed from using an unintended static hostname when /etc/hosts is unavailable or mismatched? What explicit steps can be taken to verify that the resolved hostname aligns with the desired identity in all environments?