It seems as though that the status message key for locally blocked users and ips is the same message key, however, the message params are different. Perhaps we could differentiate using these somehow (though it feels completely wrong to do so)

After some digging around I got these findings so far:

• Relying on the message key returned from WikiPageEntityStorePermissionChecker.php is tricky. As mentioned in the previous comment, we would get the same message key both for when the permission target is an IP and when the permission target is a User (blockedtext).
• I found another edge case that will return a generic permission error message: When a user is blocked by ID and the option to also block the last IPs this user edited from, the message key that will be returned is autoblockedtext for any other user trying to edit from this IP (anon or not).
• Instead of relying on the message key we could rely on the BlockTarget instance that is included in the PermissionStatus returned from the permission manager in the above method (point 1). These can be either UserBlockTarget or AnonIpBlockTarget. That would however require a bit of a rewrite to our current method that relies on message keys. And requires some research if we can get the DatabaseBlock instance by the blockId (or otherwise somehow changing WikiPageEntityStorePermissionChecker to not throw away the DatabaseBlock instance).

Change #1215079 had a related patch set uploaded (by Itamar Givon; author: Itamar Givon):

[mediawiki/extensions/Wikibase@master] [WIP] Repo: Add block target info to api data

https://gerrit.wikimedia.org/r/1215079

Change #1215080 had a related patch set uploaded (by Itamar Givon; author: Itamar Givon):

[mediawiki/extensions/Wikibase@master] [WIP] CRUD: Improve error messages for blocked IPs

https://gerrit.wikimedia.org/r/1215080

Change #1215220 had a related patch set uploaded (by Itamar Givon; author: Itamar Givon):

[mediawiki/extensions/Wikibase@master] [WIP] CRUD: Refactor blocked user detection

https://gerrit.wikimedia.org/r/1215220

Change #1215728 had a related patch set uploaded (by Itamar Givon; author: Itamar Givon):

[mediawiki/core@master] Add Block Target Type to 'blockinfo'

https://gerrit.wikimedia.org/r/1215728

Change #1215729 had a related patch set uploaded (by Itamar Givon; author: Itamar Givon):

[mediawiki/extensions/Wikibase@master] Repo: Remove code to pass down a block target type

https://gerrit.wikimedia.org/r/1215729

Change #1215079 merged by jenkins-bot:

[mediawiki/extensions/Wikibase@master] Repo: Add block target info to api data

https://gerrit.wikimedia.org/r/1215079

Change #1215220 merged by jenkins-bot:

[mediawiki/extensions/Wikibase@master] CRUD: Refactor blocked user detection

https://gerrit.wikimedia.org/r/1215220

Change #1215080 merged by jenkins-bot:

[mediawiki/extensions/Wikibase@master] CRUD: Improve error messages for blocked IPs

https://gerrit.wikimedia.org/r/1215080

Change #1215728 abandoned by Itamar Givon:

[mediawiki/core@master] Add Block Target Type to 'blockinfo'

Reason:

We decided to prioritize work on T411913 instead

https://gerrit.wikimedia.org/r/1215728

Change #1215729 abandoned by Itamar Givon:

[mediawiki/extensions/Wikibase@master] Repo: Remove code to pass down a block target type

Reason:

We decided to prioritize T411913 instead

https://gerrit.wikimedia.org/r/1215729

Test wiki created on Patch demo by ItamarWMDE using patch(es) linked to this task:
https://627937483f.catalyst.wmcloud.org/w/

Ready for validation. Instructions on how to block an IP:

1. Go to https://627937483f.catalyst.wmcloud.org/w/
2. Make an anonymous edit (in the browser console):

$.ajax({
  url: 'https://627937483f.catalyst.wmcloud.org/w/rest.php/wikibase/v1/entities/items/Q1/statements', 
  type: 'POST',
  contentType: 'application/json',
  data: JSON.stringify({
    "statement": {
      "property": {
        "id": "P1"
      },
      "value": {
        "type": "value",
        "content": "test"
      }
    }
  })
});

3. Go to https://627937483f.catalyst.wmcloud.org/w/index.php?title=Item:Q1&action=history and check the ip address of the last edit.
4. Log in as user "Patch Demo"
5. Go to https://627937483f.catalyst.wmcloud.org/wiki/Special:Block
6. Block the IP address from step (3)
7. Log out
8. Try to make the same call as in step (2)

To also test global blocking:

9. Log in as "Patch Demo"
10. Unblock the ip by going to https://627937483f.catalyst.wmcloud.org/wiki/Special:BlockList and pressing the "remove block" link for the ip's entry
11. Go to https://627937483f.catalyst.wmcloud.org/wiki/Special:GlobalBlock and block the same ip from step (3)
12. Log out
13. Try to make the same call as in step (2)