Naming convention for field type templates? It seems that the naming convention for field types is undocumented. Looking at the classy theme shows a seemingly arbitrary convention. For example, the Text (formatted, long, with summary) type as displayed in the UI is apparently named field--text-with-summary.html.twig as a template file.

What are the naming conventions for field types and how could I have determined them myself?
The naming convention for field templates is documented here, Twig Template naming conventions


  
  field--node--[field-name]--[content-type].html.twig
  field--node--[field-name].html.twig
  field--node--[content-type].html.twig 
  field--[field-name].html.twig
  field--[field-type].html.twig field.html.twig
  


But field--text-with-summary.html.twig is one of those that is harder/trickier to figure out from just looking at the Field Type.





To make Drupal life easy for this, you can enable Twig Debug. See Locating Template Files with Debugging

Now when you inspect element with browser, you can see which template file is being used (the one with the "x") and what other available template file names (the ones with "*") you could use.