v1.89.0

Added

• Two new values for BenchRunCfg.regression_method: "delta" and "absolute". Each selects a dedicated detector and its threshold comes from a new BenchRunCfg field:
  • "delta" uses regression_delta: largest acceptable absolute-unit change of the current run's mean from the mean of all historical per-time means, respecting the result variable's OptDir. Useful when a percent threshold obscures sensitivity at tiny baselines or when CI wants a flat unit ceiling on drift.
  • "absolute" uses regression_absolute: hard directional threshold (ceiling for OptDir.minimize, floor for OptDir.maximize) against the current run's mean. No history required — fires on the very first recording.
• detect_delta() and detect_absolute() public detectors in bencher.regression, mirroring the detect_percentage / detect_adaptive shape so they participate in the shared plot/report pipeline.
• detect_regressions() now runs with a single over_time point when regression_method="absolute", so contractual limits can gate even the initial benchmark run.
• Gallery examples example_regression_delta and example_regression_absolute demonstrating the new methods.

Changed

• Regression diagnostic plot: when the adaptive detector produces both a MAD band and a percent band, they are now merged into a single combined acceptance band (the union of both — matching the adaptive gate, which flags a regression only when both tests fail). Previously the plot layered two separately-coloured bands.