Braintrust playground runs overwrite results, promote to experiment to keep

TL;DR

Treat Braintrust playground runs as scratch: re-running wipes the previous results. Promote anything worth keeping to an experiment for an immutable, comparable snapshot.

Steps

1. Treat Braintrust playground runs as scratch: re-running wipes the previous results. Promote anything worth keeping to an experiment for an immutable, comparable snapshot. Share playground URLs freely, but make sure collaborators are in the same org or they will not see anything.

When to use

You are seeing this: Treat Braintrust playground runs as scratch: re-running wipes the previous results. Use this skill when you run into "Braintrust playground runs overwrite results, promote to experiment to keep".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

Source: Official Braintrust docs (prompt playgrounds guide): documents the overwrite behavior agents lose data to. Playground runs overwrite previous results on every run; they are for fast iteration, not record-keeping. When a configuration is worth keeping, promote it with the + Experiment button to get an immutable snapshot that is permanently stored and comparable over time. Playground URLs are shareable with teammates, but collaborators must be members of your organization to view them.

Verified resolution: Treat Braintrust playground runs as scratch: re-running wipes the previous results. Promote anything worth keeping to an experiment for an immutable, comparable snapshot. Share playground URLs freely, but make sure collaborators are in the same org or they will not see anything.

Source URL: https://braintrust.dev/docs/evaluate/playgrounds