As Community-Tech team is rolling out Multiblocks, we're discovering a lot of gadgets and user scripts that assist sysops with issuing a user talk message after blocking a user. This is a very common workflow, so much so that I wonder if it should be part of Core. That seems better than reinventing the wheel over and over again.

Of course, not all wikis or individual sysops will follow this practice, so this should be configurable, perhaps via MediaWiki-extensions-CommunityConfiguration.

I envision a configuration where sysops can:

• State whether or not they want this functionality at all
• Provide a list of block templates that are commonly used
• Be able to customize parameters passed to the templates and the values passed to them
  • Use TemplateData to grab available params
  • Maybe a dropdown of values we offer, such as the expiry and the reason (the username can be provided, too, but that can also be substituted with {{subst:REVISIONUSER}}).
  • Also an option for free-form wikitext entry, if the template takes a supplemental message
• Whether to use substitution (in my opinion that should be enforced)

Then at Special:Block:

• A new checkbox, "Issue block notice to the User talk page", could go under the "Additional options" at the bottom
  • Note, should not be present for IP ranges, though the same is true currently for other options like "Watch the target's user page and talk page")
• Checking that will reveal a dropdown of the templates to select from, as configured by the community
  • And also a text field, if the template is configured to take a supplemental message
• If the block reason matches one of the templates (templated reasons like {{anonblock}}), auto-select that from the dropdown
• After a successful block is made, the talk page notice is sent and success/failure is shown to the user, beneath the current success message for the block itself. (They should be separate messages, I think)