Document portal paths not accessible after reboot even when permissions persist

[haydntrowell]

I'm developing a GTK4/Rust text editor distributed as a Flatpak. I've had a long-standing issue where my recent files list stops working after a reboot, and wanted to check if this is a known issue and whether there's a solution or workaround I'm missing.

I store recently opened files by saving the URI returned by gio::File::for_path(...).uri(). For files opened via the file chooser portal, this gives us paths like file:///run/user/1000/doc/ec355f77/basic-report.typ.

Here's what I've confirmed through testing:

• flatpak permission-show confirms that permissions persist across reboots as the document IDs are still there
• After a reboot, the stored URIs resolve to paths via GIO (gio::File::for_uri(...).path() returns Some)
• However, path.exists() returns false for those paths, and attempting to open them gives "No such file or directory"

I was pointed to issues #1362 and #1845 as potentially related. Is this a known limitation of the document portal, and is there a recommended way for sandboxed apps to re-open previously accessed files without requiring the user to go through the file chooser again?