Compare graph history

Atlas saves the active integration graph immediately before and after each applied scan. These checkpoints make it possible to answer what changed across one scan or several scans without reading the source files again. They include active entities and relationships, including relationships marked rejected. They contain names and basic graph attributes, with redaction applied again at capture; they do not copy evidence, snippets, source paths or metadata.

Compare your first scan

1. Open the local app with atlas serve, then open Scans.
2. Preview a folder, then choose Apply scan. Preview does not create a checkpoint. An applied scan saves Before and After checkpoints.
3. In Compare graph history, leave the latest scan’s Before and After selected. The cards show entity and relationship counts at each end, plus added, changed and retired totals.
4. Expand a changed row to inspect its old and new values. Filter by entity or relationship, action, or name. Load more changes pages through the complete result when the initial list is bounded.

For a concrete example, scan a copy of examples/northstar into a workspace of your own, edit one input file in the copy, and scan the same folder again. Choose After for the first scan and After for the second to inspect the net graph change. Atlas compares saved states: a row added and then retired between the chosen points does not appear as a net change. The individual scan diff remains available in Scan history.

What counts as history

Checkpoints begin with scans applied on v0.4.0 or later, through either the web app or CLI. Earlier scans retain their original per-scan diff, but Atlas cannot rebuild their full historical graph from that bounded list. A fresh applied scan captures its own before and after states, including the graph that existed before upgrading. Loading the demo does not create a scan checkpoint; scanning the Northstar example files into your own workspace does.

An entity edited or a relationship reviewed between scans appears in the Before checkpoint of the next scan. The current Atlas graph continues to show today’s state; viewing history does not change it. A snapshot captures only active rows and relationship endpoints that are active at that moment. If a comparison has no net changes, the two selected graph states are equal for the captured attributes.

The comparison API is available locally at GET /api/scans/checkpoints and GET /api/scans/compare. It requires a workspace and ordered checkpoint pair, returns exact totals, and pages the detailed changes. No remote service or source-server scanning agent is involved.