Expand description
m4a subservice: the node-side messenger key vault (m4a-agent 0.4).
Keys live in the vault under <data_dir>/m4a/.m4a-agent/. The vault master
key is never on disk and never created here: it comes from the environment
variable named by HATCHERY_M4A_MASTER_KEY_VAR (a secret the host
injects). Identity is by key signature; no password exists. Agents never see
this service, its vault or the master key.