The study facade exposes the orchestration objects users may import directly:
Study, StudyExactAsyncStepSession, StudyExactAsyncStepResumeHandle, and
RunExecutionFailed.
Study carries separate generic axes for evaluator/kernel payload attempts and
run-method feedback records. Exact-async step sessions and resume handles keep
the same split: suspended sessions store payload attempts, and finish()
materializes successful payloads into request-aligned records immediately before
calling RunMethod.tell_attempts(...).
Exact-async resume handles are live evaluator/session handles, not durable checkpoint artifacts. The built-in joblib async evaluator keeps suspended work inside the same evaluator instance's process-local runtime state, so those handles are not a crash-recovery or process-restart persistence format.
Use the root facade or variopt.artifacts for EvaluationAttemptBatch,
EvaluationFailure, KernelDiagnostics, and KernelStatus. Use
variopt.artifacts for artifact-construction names that are intentionally not
exported from the trimmed root facade, including EvaluationSuccess.
Deep modules such as variopt.kernel are importable implementation modules,
not supported artifact facades.
::: variopt.study