`model.key_env` is not custom-only: the Desktop settings UI stores REGISTRY
provider keys there (e.g. HERMES_CUSTOM_LMSTUDIO_API_KEY with provider
lmstudio, #106336) and auth._model_level_key_env honours it. The previous
predicate (`not custom or route_changed`) therefore wiped that pointer on a
same-provider same-base_url model re-pick and silently broke the user's
credential. The pointer now clears ONLY when provider or base_url changed;
the inline api_key/api rule is unchanged.
Custom-endpoint activation (model_setup_flows_custom) popped base_url /
api_key but never key_env, so a stale pointer from a previous endpoint
outranked the credential it had just written — pop it alongside.
Tests: the same-route re-pick case now covers a registry provider (red on
the old predicate), and the two clear_model_endpoint_credentials tests are
folded into one invariant.
teknium1
5bccc4e238