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Feature Flag Evaluation Lab

Watch one request move from a versioned flag snapshot through prerequisites, sticky rollout, variant assignment, and a local kill switch.

Scenario controlsChange the request context and watch the same flag produce a different verdict.
control planeflag snapshotversion 129local evaluatorSDK cachestream currentsafety railcache + kill switchdependency greenrequest contextMaria from BerlinDE · promaria-berlin-44rule engineprerequisitescountry okplan oksticky cohortbucket 26threshold 25%hold on classicrequest pathclassic pathnot in cohortdependency healthybucket bar: green means the subject is inside the rollout thresholdreq
Snapshot state
version 129
Live stream connected. New control-plane versions can replace the local cache.
Rule path
Country and plan pass prerequisites, so percentage rollout decides the outcome.
Rollout verdict
Bucket 26 sits above the 25% threshold.
Safety override
Local dependency health is green, so the kill switch does not override the variant.
Live flag shapeThis is the kind of runtime policy the evaluator is applying.
flag payments_orchestrator_v2 fallback classic if country in [DE, GR, CZ, PT, NL] and plan in [pro, business] serve v2 when hash(payments_orchestrator_v2 + ':' + userId) % 100 < 25 else serve classic if paymentsDependencyHealthy is false force classic
Step 1 / 7The control plane publishes a versioned flag snapshot

A feature flag usually starts as config, not as a request-time network lookup. The control plane stores the rules, rollout percentage, fallback, and audit version for this release.

Operators change policy once in the control plane; applications reuse the published snapshot many times.

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