Checks variable ranges/types, expressions, constraints, evaluator
    availability and parameter schemas, and administrator budgets.  Use
    ``strict`` to surface non-deterministic evaluators and oversized budgets.
    

    ``execution_mode="sync"`` waits for completion and returns the summary.
    ``execution_mode="async"`` returns immediately with a ``run_id`` and
    ``status``; poll it with ``optimization.get_result``.  A repeated
    ``client_request_id`` returns the existing run instead of starting a
    duplicate.
    

    Full candidate populations are never returned; ``top_solutions`` is
    capped by the run's ``top_k``.  Set ``include_top_solutions=false`` for a
    smaller response.
    

    Default page size is 20; the administrator maximum is enforced.  Pass the
    returned ``next_cursor`` to fetch the next page.
    

    Cancellation is cooperative first; if the worker does not stop within
    the grace period, its process group is terminated.  ``accepted`` and
    ``termination_confirmed`` are reported separately.
    

    When objective definitions, variables, constraints, evaluator versions or
    parameters differ, ``comparable=false`` and no single improvement
    percentage is produced.