ReasoningTokenShare metric

@synalinks_export("synalinks.metrics.ReasoningTokenShare")
class ReasoningTokenShare(LMOperationalMetric):
    """Fraction of completion tokens spent on reasoning:
    reasoning_tokens / completion_tokens. Signals whether a thinking
    model is actually thinking on the workload.

    Example:

    ```python
    program.compile(
        metrics=[
            synalinks.metrics.ReasoningTokenShare(),
        ],
    )
    ```
    """

    def __init__(self, name="reasoning_token_share"):
        super().__init__(name=name)

    def result(self):
        completion = self._delta("completion_tokens")
        if completion <= 0:
            return 0.0
        return self._delta("reasoning_tokens") / completion