When a file changes on disk

AI agents often rewrite a file while you have it open. Skimmark keeps watch on every file that has an open tab.

What Skimmark notices

A change to the file. Another app or an agent writes new text into it.
A replaced file. Many editors and agents save by writing a new copy and swapping it in. Skimmark treats that the same as a change.
A moved or deleted file. The file is gone from where you opened it. If it comes back to the same place, Skimmark notices that too.

Skimmark notices a change within about a second of the save.

Some saves change nothing: the app writes the same text that was already there. Skimmark ignores those.

Skimmark only watches files you have open. When you close a tab, Skimmark stops watching that file.

What you see

The file changed. The tab shows the new version in place, with no animation and no new tab. The notice bar says "File changed on disk." for 3 seconds.
The file was moved or deleted. The tab keeps showing the last version it had, and the notice bar says "File moved or deleted. Showing the last version." The notice stays while the file is gone.
The file comes back. If a file with the same name appears in the same place again, the tab loads it and the notice clears.
A tab you are not looking at. It updates quietly. If its file is gone, you see the notice when you switch to that tab.

If Skimmark cannot read the new version for another reason (for example, it no longer has permission), the tab keeps the last version and the notice bar says "Could not open" with the reason.

Screen readers announce each notice once, politely, without moving focus.

Your place is kept

When the tab you are reading updates, the view stays on the same text. Skimmark remembers the paragraph, heading, list item, or table at the top of the window and puts it back in the same spot, even when the change added or removed text above it.

The text you were reading was changed or removed. The view goes to the nearest heading above where you were. If there is no heading above it, the view goes to the top of the file.
You were at the very top of the file. You stay at the top.
A tab you are not looking at. It keeps its scroll position as it was. Your place is kept by text only in the tab on screen.
Images above your place. As they finish loading, Skimmark keeps your text where it was for a couple of seconds, until you scroll yourself.
Very long files (over about 100,000 characters). Skimmark does not track your place by text; the view stays at the same scroll position.

Good to know

Skimmark only reads your files to check them. It never changes them.
Other files in the same folder can change all they like. Only open files matter.
On a Mac where the system service that reports file changes is silent, Skimmark notices and switches to a backup method automatically.