Xcode

Not needed! As of Xcode 15, logs can be filtered by library by right clicking them in the output.

Setting the OS_ACTIVITY_MODE = disable environment variable for the current scheme may hide noisy system library messages from the output. Possibly all NSLogs as well though?

pluginkit is a command line program that can help deal with extensions. In particular, it may be of use assigning the right extension to launch.

• List extensions by type: pluginkit -m -p com.apple.dt.Xcode.extension.source-editor
• Verbose output, with duplicates: pluginkit -m -p com.apple.dt.Xcode.extension.source-editor -A -D -vvv
• Remove problematic extension: pluginkit -r path/to/extension
• Add an undetected one (maybe): pluginkit -a path/to/appex

If the problem is instead with multiple copies of Xcode.app, re-register the main one.

$ PATH=/System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support:"$PATH"
$ lsregister -f /Applications/Xcode.app