Saves the snippet an extension ships into the editor's Studio list when a site is set up, on runtime:provision:snippets (MishkaCmsCore.Runtime.ExtensionProvision, which describes the payload as MishkaCmsCore.Runtime.ExtensionProvision.snippet_payload/0).

NOTHING IS EVER UPDATED, as in the rest of a provision: a site that already holds the snippet keeps its row, edited or not, and the name is not reported.

A REFUSED WRITE COMES BACK AS error, never as a raise. A plugin that raises is skipped and the event answers the payload it was given, so a raise here would read as "nothing to install" and the admin would never hear that their snippet was refused. The run raises with the reason instead.

It writes for whoever runs the provision, as the pages beside it are written: nobody (the seeds, the install wizard) writes as the system, a master through the master action with the site named, and a site admin through their own site's action under its tenant.