Actually, this is not just a question and closer to feature request. But there is almost nothing should be done in dart_code_metrics to implement this feature.

A relatively new dart analyze command (which replaces dartanalyzer) uses analysis server to perform linting. dart tool launches analysis server and communicates with it to get code analysis issues. I actually spent some time and investigated this scenario. I see that plugins (and dart_code_metrics plugin) in such scenario are being loaded and work properly.

But issues found by dart_code_metrics are not reported in this scenario: analysis server shutted down too early by dart tool.

There is an issue in Dart SDK repository which blocks us from using the plugin inside dart analyze workflow:
dart analyze does not know when analyzer plugin results are complete

I decided to open this issue just to track Dart SDK issue . The issue has P3 status and I hope it will be fixed relatively soon. My proposal is document ability to run dart_code_metrics using dart analyze after Dart SDK issue is fixed.

I suppose it would be more convenient to use the plugin with "standard" workflow with dart analyze , please let me know what do you think about this.