The Xcode 26.4 beta 2 seems to address the problem. A side effect it made the Xcode 26.3 unable to find metal toolchain at all - least the current workaround stopped working.

I re-installed macOS 26. RE-INSTALLED it, in case that is something with permissions. Only to face the very same bug with Xcode 26.2 I don't know what, why, and how, but this problem has no reasonable solution [object Object]

~ ❯ ls -alR /var/run/com.apple.security.cryptexd/ total 0 ls: /var/run/com.apple.security.cryptexd/: Permission denied I could change the permissions to "g+rx", but that group access is reset on system restart and does not persist

I tried that, unfirtunatly that did not change a thing here ~ ❯ sudo chmod o+rx /var/ ~ ❯ sudo chmod o+rx /var/run/ ~ ❯ sudo chmod o+rx /var/run/com.apple.security.cryptexd/ ~ ❯ sudo chmod o+rx /var/run/com.apple.security.cryptexd/mnt/ ~ ❯ cd /var/run/com.apple.security.cryptexd cd: permission denied: /var/run/com.apple.security.cryptexd

unfortunately that is not helping. ~ ❯ sudo chmod +r /var/run/com.apple.security.cryptexd/mnt/ ~ ❯ ls -al /var/run/com.apple.security.cryptexd/mnt/ ls: /var/run/com.apple.security.cryptexd/mnt/: Permission denied ~ ❯ cd /var/run/com.apple.security.cryptexd cd: permission denied: /var/run/com.apple.security.cryptexd ~ ❯ sudo chmod +r /var/run/com.apple.security.cryptexd ~ ❯ cd /var/run/com.apple.security.cryptexd cd: permission denied: /var/run/com.apple.security.cryptexd

❯ ls -l /private/var/run/com.apple.security.cryptexd/mnt/ ls: /private/var/run/com.apple.security.cryptexd/mnt/: Permission denied

the original message is exactly that command (but the formatting broke the output)

yes, it is reproducible. no reboot help

I reported it a while ago FB20178568 FB20645387 (no response so far)

That did not help to me. Toolchain download, but Xcode can't use the downloaded Toolchain for some reason: "EnableLiveAssetServerV2-com.apple.MobileAsset.MetalToolchain" = on; ProductName: macOS ProductVersion: 26.0.1 BuildVersion: 25A362

yes, Metal component is installed, but it "Failed to remount the Metal Toolchain" and Xcode can't use it for some reason

I analyzed again the alignViewportToDocumentEndLocationIfNeeded() you provided, and noticed that despite it being called from textViewportLayoutControllerDidLayout the viewportLayoutController.viewportRange! is sometimes nil (and crashes). I also noticed that the adjustement sometimes failing to adjust viewport to display the end of the document - all of that happens when scrolling is done fast - I'm aware it is vague, but I don't have more context to it myself, it looks misterious to me

I don't see any way to achieve that, unless you ensure the layout of the whole document that is also my experience. However, the NSTextView/UITextView somehow maintain stable scrollbar position while scrolling (moving the viewport). We struggle to understand how to archive the same with TextKit2 API. Any advice?

FYI the code you proposed is very slow and unusable in production setup. I wish we had a better way to calculate usageBoundsForTextContainer in a performanet and realiable (or usable really) way

The Xcode 16.3 can't build my project due to mysterious crashes, so this is impossible in the near future.