Composite: temporarily inconsistent overlay registrations in DB

[kofa73]

Describe the bug

• When I start, image 12650 does not have an overlay:

sqlite> select * from overlay;
12292|12293
12290|12291
12291|12292
12293|12294

• When an overlay is added to an image, an entry is added to the table overlay, connecting the two image IDs:

sqlite> select * from overlay;
12292|12293
12290|12291
12291|12292
12293|12294
12650|12638

My processing stack is (observe that the overlay is a black-and-white version of the image, for demonstration purposes):

• I'll now add another composite instance, and use the same overlay:

sqlite> select * from overlay;
12292|12293
12290|12291
12291|12292
12293|12294
12650|12638

The DB contents do not change, which is OK, 12650 is only associate with one image as overlay.

• I'll now replace the overlay image with another in the 2nd composite instance (this is a colour version):

sqlite> select * from overlay;
12292|12293
12290|12291
12291|12292
12293|12294
12650|12639

Observe that 12638 disappeared from the DB, only 12639 is shown.

• Leaving the darkroom fixes this:

sqlite> select * from overlay;
12292|12293
12290|12291
12291|12292
12293|12294
12650|12638
12650|12639

While probably not a serious issue (the registration gets fixed), I'm wondering if it were possible to always keep the DB in sync with the modules.

Steps to reproduce

See above

Expected behavior

dt should keep the DB consistent at all times

Logfile | Screenshot | Screencast

No response

Commit

No response

Where did you obtain darktable from?

downloaded from www.darktable.org

darktable version

4.9.0+925~gb7288e18b2

What OS are you using?

Linux

What is the version of your OS?

Ubuntu 24.04

Describe your system?

No response

Are you using OpenCL GPU in darktable?

None

If yes, what is the GPU card and driver?

No response

Please provide additional context if applicable. You can attach files too, but might need to rename to .txt or .zip

No response