It would be nice if developers can communicate regarding the re-running the test for the specific source file. For example, we have a source file named "runme.cpp". There is a test driver file for this file named "runme_test.cpp" which basically performs all kinds of testing for the source file. Every Time, "runme.cpp" is updated and ready for review, developer has to update the test driver file again and run it to make sure that it covers latest changes - which is pretty standard. Now, sometimes a review can just include minor updates like Incorrect Naming Conventions/Correct Indentations/Add more description & comments etc.
These types of review do not require a test driver file to be re-run. My suggestion here is to have another option 'RE-RUN' just like ACTION with two options - YES or NO and possibly give a green/red color indication on the top of the review or somewhere in description.
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This sounds specific to your local installation. Maybe it's better to implement this yourself locally as a custom field?
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I'm not exactly sure what this is asking for -- it sounds like you just want a more convenient way to post a comment asking revision authors to "Please re-run the optional tests."?
This is extremely niche/unusual and not something that makes sense to support in the upstream. You could try modifying Phabricator, or maybe use a Javascript bookmarklet.