The answer to “How should you @-mention someone you are replying to?”¹ can depend on many factors or a few. Context matters somewhat, sometimes.
We can simplify it to 2 questions, based on 1 directive:
* Elevate #IndieWeb domains, above any silo or @-@ identities
Two questions and answers:
1. Do they have an #IndieWeb domain? Then @-domain mention them², like you are speaking to them at their domain identity. This will notify them there, or at least reinforce their domain’s importance.
2. Was their post only published on a silo (or #fediverse instance), or was it POSSEd to a silo (or fediverse instance) and you plan to POSSE (or federate) your reply³? Then use their silo @-name (or @-@ address), in parentheses if (1). This will notify them on that silo (or instance), and may help thread your POSSE reply.
If the author has their own domain:
Reply to an IndieWeb post (& POSSE toot): https://tantek.com/2023/008/t1/
* @-domain (@-@)
Reply to an IndieWeb post (& POSSE tweet): https://tantek.com/2023/016/t1/
* @-domain [that matches their Twitter @-name]
Reply to a toot: https://tantek.com/2023/008/t4/
* @-domain (@-@)
Reply to a tweet: https://tantek.com/2023/002/t2/
* @-domain (Twitter @-name)
If the author does not have their own domain:
Reply to a toot: https://tantek.com/2023/002/t4/
Reply to a tweet: none since this series, though it would be of the form:
* Twitter @-name
This is day 17 of #100DaysOfIndieWeb #100Days, again finished the next day.
← Day 16: https://tantek.com/2023/017/t1/socialweb-blogs-reply-comment-post
→ Day 18: https://tantek.com/2023/019/t5/reply-domain-above-address-and-silo