/**
 * test_runtime_health_backoff — Story 6.5 regression suite.
 *
 * Three scenarios:
 *   1. Exponential schedule: failure N produces delay ≈ 10s * 2^(N-1)
 *      with a 1h cap; explicit unit test on the pure function.
 *   2. markFailure + markHealthy: failures accumulate, until extends with
 *      backoff, markHealthy resets to failures=0 and clears
 *      permanentlyDown.
 *   3. Retry budget breach: more than MAX_FAILURES failures within the
 *      window flips permanentlyDown=true and isCoolingDown()=true.
 *
 * Prints TEST_RUNTIME_HEALTH_BACKOFF_OK on full pass.
 */
export {};
