I've read through T3669: Make it easier to remember to submit inline comments when updating a diff, and as a user of 3 years, I still find myself forgetting to submit comments sometimes... until a coworker brings it up.

My current workflow is:

1. Send code for review—which is then rejected with comments.
2. Address each comments: for each comment, reply to it (unsubmitted) and make the relevant changes to the code.
3. Submit the diff
4. ??? Remember to go back to the UI and submit the comments ???

A couple of ideas (in order of favorite to least favorite) that would fix this and hopefully wouldn't be annoying for existing users who don't have this problem:

1. arc diff asks if you'd like to submit the unsubmitted comment. Mockup:

» arc diff
   You have not specified any reviewers. Continue anyway? [y/N] y  <-- example of existing UX
   You have unsubmitted comments. Submit them? [y/N] y             <-- this

2. If that's too noisy, maybe a config flag like arc.diff.submitcomments either a boolean, or possibly an enum of 3 states: prompt, true, false
3. Maybe add support for a conduit call so that I can programmatically submit comments (similar to T2538) after running arc diff
4. Current workaround may be to set an alias for arc diff --browse (is there a way to configure .arcrc to always include this flag?)