Our Sentry project has server-side fingerprint rules defined, and we also want to set an SDK-level fingerprint on certain events. We need to know whether the SDK-level fingerprint and the project-level fingerprint rules merge, or whether one takes precedence over the other.

Server-side fingerprint rules take precedence over SDK-level fingerprinting. They do not merge. When an event matches one of your project's server-side fingerprint rules, Sentry replaces the fingerprint set by the SDK with the fingerprint from the matching rule. When no server-side rule matches the event, Sentry keeps the fingerprint the SDK set.

So, for a given event:

If you want to refine Sentry's default grouping instead of replacing it, include the {{ default }} variable in the fingerprint array. This works in both SDK fingerprinting and server-side rules, and it folds the normal grouping hash into your custom fingerprint rather than overriding it entirely. Omit {{ default }} to override grouping completely.

For matching syntax and variables, see the Fingerprint Rules documentation and the SDK Fingerprinting documentation.