2. Fixed slices per candidate

Status: accepted, 2026-10-16

Context

Experiments get ramped, with :cdn going from 0% to 5% to 20%. The obvious layout puts candidates end to end (:cdn takes buckets 0–20, :edge takes 20–40), but then growing :cdn shifts every :edge unit, and someone who was on :edge can end up on :cdn halfway through the experiment.

Decision

Candidates are sorted by name and each owns a fixed block of 10,000/n buckets. A candidate takes the first weight × 100 buckets of its own block, capped at the block size.

Consequences

Changing a weight only moves units between that candidate and :default, and a test.check property checks this. In exchange, with n candidates none of them can go above 100/n percent. Adding or removing a candidate moves every block, so it should come with a new revision. Most experiments should have one or two candidates, where the cap is 100% or 50%.