---
title: What "seen" means
slug: seen-snapshots
summary: Skimmark remembers each file as you last saw it, so it can later show what changed since. Where that copy lives and why it stays on your computer.
---

# What "seen" means

When an AI agent rewrites a file, you want to know what it changed since you last looked. Skimmark keeps a copy of each file as you last saw it. That copy is the file's **seen version**.

## When Skimmark saves the seen version

- **The first time you open a file**, Skimmark saves the version it shows you as the seen version.
- **When you mark it seen**, Skimmark replaces it with the version on your screen: see [Mark as seen](mark-as-seen.md).
- **Later opens and live updates** do not replace it. If an agent changes the file while you read, the seen version stays the one from before.
- **Closing a tab** does not change it. Neither does quitting Skimmark.

Skimmark saves the file exactly as it is on disk, byte for byte, including line endings. Files over 20 MB are not saved.

If you open the same file under another name that points to it (a symbolic link, or on Windows the same path typed in different upper and lower case), Skimmark treats it as the same file and keeps one seen version.

## See and clear what changed

To see what changed since the seen version, turn on Changes: see [Seeing what changed](changes-view.md). To accept what you see as the new seen version, press **Seen**: see [Mark as seen](mark-as-seen.md).

## Where seen versions live

Skimmark keeps seen versions in a `snapshots` folder inside its own app data folder, never next to your files:

| System | Folder |
|---|---|
| Mac | `~/Library/Application Support/com.skimmark.app/snapshots` |
| Windows | `%APPDATA%\com.skimmark.app\snapshots` |
| Linux | `~/.local/share/com.skimmark.app/snapshots` |

Each seen version is one file with a long random-looking name. `index.json` in the same folder lists which file each one belongs to and when it was saved.

## Privacy

Seen versions stay on this computer. Skimmark does not upload them or send them anywhere.

They are full copies of your files, so they hold whatever your files hold. To remove them all, quit Skimmark and delete the `snapshots` folder. The next time you open a file, Skimmark starts again from the version it shows you.