schema

Q Which schema endpoints exist, what does each cost, and what shape does each return?

Endpoint GET /api/v1/schema[/<EntityType>[/fields[/<field>]]] ± project_id

Docs claim Schema is readable over REST; project scoping via project_id.

Actual

200   573ms     13368b  /schema
                            dict, 114 keys, first: ['ActionMenuItem', 'ApiUser', 'ApiUserProjectConnection', 'AppWelcomeUserConnection', 'Asset']
200   264ms       138b  /schema/Version
                            dict, 2 keys, first: ['name', 'visible']
200   327ms     48111b  /schema/Version/fields
                            dict, 71 keys, first: ['sg_first_frame', 'sg_uploaded_movie', 'flagged', 'sg_uploaded_movie_transcoding_status', 'tasks']
200   586ms      1211b  /schema/Version/fields/sg_status_list
                            dict, 11 keys, first: ['name', 'description', 'custom_metadata', 'entity_type', 'data_type']
200   358ms     13395b  /schema?{'project_id': 70}
                            dict, 114 keys, first: ['ActionMenuItem', 'ApiUser', 'ApiUserProjectConnection', 'AppWelcomeUserConnection', 'Asset']
200   329ms     48139b  /schema/Version/fields?{'project_id': 70}
                            dict, 71 keys, first: ['sg_first_frame', 'sg_uploaded_movie', 'flagged', 'sg_uploaded_movie_transcoding_status', 'tasks']

every enumeration spelling guessed, all 404:
404   315ms       178b  /schema/entity_types
                            {"errors":[{"id":"db7b1e42661b995196c86ec0c9fab48d","status":404,"code":103,"title":"Not Found","source":null,"detail":"Entity type 'entity_types' does not exist.","meta":null}]}
404              177b  /schema/entity_type    detail: "Entity type 'entity_type' does not exist."
404              174b  /schema/entities       detail: "Entity type 'entities' does not exist."
404              171b  /schema/types          detail: "Entity type 'types' does not exist."
404              172b  /schema/_types         detail: "Entity type '_types' does not exist."
404              138b  /entity_types          detail: null
404              138b  /entity                detail: null
404              138b  /api/v1/entity         detail: null

Teaches

• A connection type's REST slug collapses the doubled underscore. Asset_linked_projects_Connection is addressable as itself or as asset_linked_projects_connections, while the naive snake_case rule gives asset_linked_projects__connections, which 404s. Ten types on the probed site are affected (recipes/003).

Sizes below are from the probed site.

• /schema/<x> addresses one entity type, so an enumeration path under it is read as a type name and 404s saying so: entity_types, entity_type, entities, types and _types each return Entity type '<x>' does not exist. Off that prefix, /entity_types, /entity and /api/v1/entity 404 with detail: null. /schema is the type list; there is nothing lighter.
• There is no cheap middle tier: anything about a type costs the /fields call, so drill straight to one field with /fields/<field> when you know the name.
• project_id is accepted on both /schema and /fields and does change the body (13368 → 13395b, 48111 → 48139b), so a project-scoped schema is not the site schema. Cache the two under separate keys (see the .schema-cache/<site>/<site|pNNN>/ split).
• Site settings are not under /schema. GET /preferences returns 200 with 17 keys, hours_per_day and duration_units among them (field_types/duration).
• Nothing in a field's block names where the field came from. visible.editable is the closest reading and the sg_ prefix is not one at all (probe 056).
• Counts are site state, not API constants. On the probed site, /schema returned 114 types and Version 71 fields, against 113 and 61 on an earlier run. Measure and cache; never hardcode a count or a field list.