FA-74069 / Feature flag rollout bucketing / Member archive

Mutually exclusive layer allocation: Range ends are inclusive · case 04

The user at a shared boundary is claimed by the earlier experiment, so adjacent ranges overlap.

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

bucket = int(md5(layer_salt + ":" + user) hex, 16) % 1000. experiments is an ordered list of {name, start, end, paused?} with start/end in percent (one decimal) converted to permille by round(x * 10); ranges are half-open [start, end). The first listed range containing the bucket decides: a paused experiment reserves its range (user gets None). Return [bucket, name or None].

Why this case matters

Layers keep concurrent experiments from overlapping on the same users.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
bucket at range end belongs to next range	`[988, "x"]`	`[988, "y"]`	Failed

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