What the SDK does without an account

next-evolve is MIT-licensed, but on its own it doesn't run experiments: the configuration (the signed bundle), the statistics and the dashboard come from Evolve Cloud. Without a working connection, your site keeps working as if Evolve weren't there.

#No account, no key, or no bundle yet

If EVOLVE_SECRET_KEY isn't set, the key is invalid, or the site has never started an experiment:

Every page renders control: the props in your code.
No cookies are set.
Nothing is recorded (no assignments means no exposures; the collect route drops visitors without an evolve_id cookie).
There's no network call on the request path. In the background the SDK tries to fetch a bundle (every 60 s) and logs no bundle yet (no experiment has started): serving control or bundle fetch failed (…), at most once a minute.
npx next-evolve pull writes an empty build bundle and never fails the build.

Removing Evolve is the same as never having added it: delete the <Optimizable> wrappers (render the component directly) or leave them; they render control.

#The cloud becomes unreachable

Up to 14 days: the app serves the last bundle it verified. Experiments keep running with their last weights, events keep being written to your database, and the next aggregate after the outage counts them.
After 14 days (the bundle's expiry): control for everyone, no new cookies. Events from visitors who already have an evolve_id cookie, and server events (evolve.track, /api/evolve/track), are still written; new visitors aren't recorded.

#The site is deleted

Deleting a site in the dashboard publishes an empty bundle first, so apps that fetch it serve control within one poll (or at once, through the sync webhook). After the site's data is purged (a day later), the cloud answers every request for that site's keys with 410 {"error":"site_deleted"}. The SDK treats that one answer as final: it drops its cached bundle and serves control right away, refuses the old bundle from the build bundle, disk cache or Global Config, and next-evolve pull writes an empty build bundle. Only a newer signed bundle from the cloud would end it.

#The key is revoked

The cloud answers 401, which the SDK treats like an outage: the last bundle serves until it expires (at most 14 days), then control. That's on purpose: a 401 also happens during key rotation (the old key revoked before the new one is deployed) or in a preview environment with the wrong key, and neither should switch production to control. Only 410 site_deleted does. There's no instant kill switch; to stop an experiment at once, pause it in the dashboard.

#Your database is missing or down

Serving never touches the database, so variants keep serving. Measurement stops: on serverless hosts events are dropped (one retry); on long-running Node up to 10,000 rows are buffered and written when the database is back (oldest dropped first beyond that). The aggregate route answers 503 database_error.