Mercurial in an air-gapped environment is a test of precision and discipline. Every command matters. Every byte transferred is deliberate. There is no network to lean on, no external repository to fetch from. You control the flow of data, commit history, and branch structure entirely within your sealed system.
An air-gapped Mercurial workflow begins with creating local clones on physically isolated machines. Updates move by secure, manual transfer—USB drives, encrypted files, or signed bundles. hg bundle and hg unbundle become core tools, packaging changes for offline application without risking contamination from the outside world. Push and pull exist only as physical operations, not over TCP.
Metadata integrity is paramount. Without direct compare to a remote repository, you rely on hashes, signatures, and reproducible builds. Ensuring branch alignment and avoiding divergence require strict process: designate a source of truth, timestamp every bundle, verify each application before merging.