Your team wants to move from Claude Code to Codex, or try a new model in OpenCode. That changes more than the model. The tools, permissions, instructions and checks around it change too. Fullbeam compares both complete setups on your merged PRs before you hand the new one to everyone.
Every result links back to the setup, the tasks and the commit it came from. If something wasn't measured, you see that too, instead of a number that looks complete.
They can. The same model behaves differently with different tools, instructions and checks. So Fullbeam pins everything on both sides: model, agent, instructions, skills, MCP tools, permissions and checks. Every run starts from the commit before the PR.
Pull tasks from the codebases where the new setup would become the default: maintenance, migrations, incident fixes and feature work your team already merged.
Each task runs several times on each setup. You see how much the cost varies, how often each setup fails, and which tasks only the new one breaks. One good demo doesn't get to decide the rollout.
The new setup might take routine test fixes while the current one keeps infrastructure and auth work. Fullbeam records that split. Your own tools roll it out.
Use the new setup where it wins, keep the current one where it falls short, and leave out of the rollout any kind of work you can't call yet.