Generally speaking, the logic is as follows.
If the post is not locked for editing for the current user:
- They will see "Edit question" if they have the post editing privilege or are the post owner.
- Otherwise they will see "Improve this question".
If the current user is the post owner, they will also see "Delete question" beside "Edit question" if the question isn't already deleted or locked for deletion.
On duplicate questions, moderators and gold tag badge users will see a button for editing duplicates as they had before.
But there are some closures that don't follow this general rule and don't show either the edit or the delete button. This is an oversight on my part due to the nuanced way post notices are constructed. Namely, the buttons aren't rendered if the post notice has a top but no bottom, i.e., no
<hr> or content below that.
- Any of the obsolete close reasons (e.g. "not constructive", "too localized", etc.) except "off topic".
- Duplicate questions closed prior to 2013-02-06, the date when we moved duplicate lists out of the question body and into the head.
These questions were closed a particularly long time ago, so they're probably past where a new CTA will get them edited to the point of reopening, so there's not a lot of benefit to showing them. Still, the unintentional inconsistency could be problematic. It's a real glass half bug, glass half feature situation.