This milestone is mostly about merging the new native histograms (AKA sparse histograms AKA high-res histograms) into the main branch (and hide it behind a feature flag), and only after that about declaring native histograms a stable feature (ultimately no-op'ing the feature flag). Therefore, the priorities have a slightly different meaning (because the issues do not affect the released Prometheus versions before we merge to the main branch):

• P0: Prometheus, if built from the sparsehistogram branch, doesn't work properly until this is fixed.
• P1: We must fix this before merging to main (e.g. Prometheus might not work properly even if the feature flag is not set)
• P2: We can merge to main without this but we need to fix this to declare Histograms stable.
• P3: Nice to have. Can be introduced later without a breaking change.
• P4: The future! Do not focus on this for now. (Labeled as Pmaybe.)