Baselines and branches

A baseline is the accepted screenshot of a story that the next capture is diffed against. A diff only exists relative to a baseline: without one, a story is new, not changed. Establishing baselines is what your very first build does.

Per branch. A pull request's baseline for each story is the most recent accepted screenshot on its ancestor - usually your main branch. So your feature branch diffs against main, and you see only the changes your branch introduces, not the whole history.

Only when a change is accepted - by you in the dashboard, or by your agent over MCP. Accepting promotes the candidate screenshot to the new baseline for that branch. When the PR merges, its accepted baselines carry forward to main, and every branch that later branches off inherits them.

Nine times out of ten the branch is simply behind. Someone accepted a change on main after you branched, so your baseline is older than the latest accepted screenshot. Rebase or merge main in and the phantom diff resolves.

Maybe, and it is worth a look rather than a shrug. If a changed story has nothing to do with your diff, do not dismiss it as flake and do not just re-run. It can mean a baseline moved that should not have - a story carried forward against a screenshot nobody verified. Investigate the unexplained change before you accept it; that habit is the only thing that catches a silently wrong baseline.