I have to be more specific: I wish non breakable links to posts as default behaviour in discourse, idempotent to the current functionality.
(A) A link (copied from the URL bar in a browser) to a post should always link to the post, even if the post is moved.
(B) Oneboxing (inline and full) should work for these permanent links:
original link: Filtering topic lists in Discourse - #3 by Moin
post: Build embedding / onebox support for topic filters - #2 by sam - Feature - Discourse Meta
https://meta.discourse.org/p/1820701
Suggestion
The only solution I see is to include the ID of the post in the URL: /t/{slug}/{topic-id}/position/{post-id}