custom entities

Q Which CustomEntityNN slots are enabled on a site, and where does the real display name come from?

Endpoint GET /api/v1/schema

Docs claim Custom entities are CustomEntityNN; the display name is in the schema; a slot cannot be enabled over REST.

Actual

total entity types in /schema: 114
custom entity slots present: 11
custom entity slots enabled:  11

enabled:                     (display names below are placeholders; real ones are studio-chosen)
  CustomEntity01           display='<custom entity display name>'
  CustomEntity02..07, 19, 29                                   (8 more, identical in shape)
  CustomEntity29_sg_scene_Connection display='Custom Entity29 Sg Scene Connection'
  CustomEntity66           display='<custom entity display name> '

sample of disabled slots (first 5):
  (none - every slot in /schema was visible)

slots absent from /schema: 89 (first: ['CustomEntity08', 'CustomEntity09', 'CustomEntity10'])

addressing an absent slot directly:
  GET /schema/CustomEntity08 -> 404
    {"errors":[{"id":"...","status":404,"code":103,"title":"Not Found","source":null,
                "detail":"Entity type 'CustomEntity08' does not exist.","meta":null}]}
  GET /schema/CustomEntity08/fields -> 404   same body
  CustomEntity09, both paths -> 404          same body

Teaches

• Presence in /schema is the enablement test, in both directions. A slot in the listing is enabled, and a slot absent from it is unaddressable: GET /schema/CustomEntity08 and GET /schema/CustomEntity08/fields both return 404 Entity type 'CustomEntity08' does not exist. Enumerate /schema rather than probing slot numbers.
• On the probed site every slot in /schema read visible: true, so visible: false was never observed. Treat absence, not visible, as the disabled signal. A site with a slot enabled and then disabled would settle whether visible can read False.
• Never hardcode a slot number: they are non-contiguous and site-specific. On the probed site the enabled slots are 01-07, 19, 29 and 66. Look a slot up by its name.value display name.
• A connection entity is its own type, CustomEntity29_sg_scene_Connection, and its display name is machine-derived from the type name rather than studio-chosen.
• Display names are free text and may include a trailing space (CustomEntity66 above), so match them trimmed.