OtOpcUa commits no plaintext secrets — the only secret-shaped committed value is
ServerHistorian:ApiKey='' (empty, disabled by default). Because the pre-host expander
is fail-closed AND section-agnostic, hard-committing a ${secret:} token would break
every dev/CI/integration boot for zero at-rest benefit. Instead document the token
delivery convention for all five config secrets (jwt/ldap/deploy/configdb/historian)
in docs/security.md and note the token option in the ServerHistorian comments.
Mechanism proven live: unseeded token boot fails with SecretNotFoundException at
pre-host expansion; seeded token resolves and boot proceeds. Behavior-neutral
(comment + doc only).
Joseph Doherty