`/model` fed `validate_requested_model()` a key resolved through
`agent.secret_scope.get_secret`, which (multiplexing off) reads only
`os.environ`. Hermes does not export `$HERMES_HOME/.env` into the process
environment, so a `custom_providers` entry whose `key_env` lives only in `.env`
probed `/v1/models` unauthenticated, got 401 and printed a spurious "could not
reach this custom endpoint's model listing" note while chat worked fine.
Resolve through `get_env_prefer_dotenv` — the chain `client_lifecycle` uses for
the real request — when no profile scope is installed. With a scope installed or
multiplexing active the scope stays authoritative: a scoped miss still returns
"" and never borrows another profile's `.env`/process value.
Slimmed from the contributor's two commits (same mechanism, fewer branches,
tests trimmed to two invariants).
Fixes#109315
liuhao1024
abdb31cd99