FA-74104 / Feature flag rollout bucketing / Member archive

Global holdout exclusion: Holdout percentage admits one extra bucket · case 04

A 5 percent holdout actually withholds 6 percent of users, and 0 percent still withholds bucket 0.

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

h = crc32("holdout:" + user) % 100 and b = crc32(flag + ":" + user) % 100. Users listed exactly in force get treatment (forced). Otherwise h < holdout_pct puts the user in the global holdout (control, holdout). Otherwise b < rollout gives treatment, else control (reason rollout). Return [variant, reason, h, b].

Why this case matters

A global holdout measures the cumulative effect of all launches and must stay uncontaminated.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
holdout sample 16	`["control", "holdout", 48, 62]`	`["control", "rollout", 48, 62]`	Failed

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