Snapshots

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What Are Snapshots?

A snapshot records everything about your instance that affects the build result:

• Profile setup — the metadata (Minecraft version, loader, mod list, settings)
• Directory contents — everything in import/, live/, and persist/

Snapshots don't directly touch build/. Instead, they capture the inputs so you can reproduce an exact game state later. When you restore a snapshot, your metadata and directory contents are restored — and the next deploy rebuilds build/ from that state.

When to Use Snapshots

• Before a risky change — updating a major mod, switching loaders, tweaking configs
• Before experimenting — trying out a new modpack configuration you might want to undo
• For "save scumming" your mod setup — keep a snapshot of your stable setup and one for experimentation

Creating a Snapshot

1. Select your instance.
2. Open the Snapshots section.
3. Click Create Snapshot.
4. Give it a name and optional description.

Polymerium records the current profile setup and the contents of persist/, import/, and live/.

Restoring a Snapshot

1. Open the Snapshots section for your instance.
2. Select a snapshot from the list.
3. Click Restore.

Polymerium restores the profile metadata and directory contents to the state they were in when the snapshot was taken. Your game directory (build/) will be rebuilt on the next deploy to match that state.

Restoring a snapshot doesn't immediately modify build/. The next deploy will reproduce the snapshot's state.

Comparing Snapshots (Diff)

You can compare two snapshots to see exactly what changed between them:

• Metadata changes — different mods, version, or loader settings
• Added files — new files in persist/, import/, or live/
• Removed files — files that existed in the earlier snapshot but not the later one
• Modified files — same path but different contents

This is useful for understanding what a mod update or config change actually did to your instance.

Snapshot Storage

Snapshots store the actual profile setup data and directory file contents — not references to a cache. This means snapshots are self-contained and can be restored even if the shared cache has been cleared.

Snapshots vs. Backups

Snapshots are lighter than a full backup and faster to create. They capture the inputs, not the entire deployed output — which is all you need, since build/ can always be reconstructed.