076 page visibility: Flow PT REST finding

Q How many Page and PageSetting rows does a script, an Admin and an Artist read, and does a person read other people's per-user overrides?

Endpoint POST /entity/pages/_search ; POST /entity/page_settings/_search ; GET /entity/page_settings/<id>

Docs claim Silent.

Actual

            pages  (project, site)   PageSetting on them  shared  per-user
  script     1107  (994, 113)        1134                 1109    25, all another's
  Admin      2048  (1352, 696)       2076                 2050    22 another's, 4 own
  Artist      107  (0, 107)           120                  109    11, all another's

Admin reads 941 pages the script does not, and none the script reads are missing:
  shared {true: 900, false: 41}; ui_category {defaults: 480, app: 303, project: 115, admin: 23, other: 20}
  page_type {canvas: 433, detail: 271, stream_detail: 227, ...}; created by that Admin 550, by another 391
  GET /entity/pages/<one of those ids> as the script -> 404; PageSetting for them as the script: 0 of 941
Artist reads 1000 fewer than the script, 0 extra, and no project page at all

fields=current_user_can_see, _search pages of 500:
  script  all 200          Artist  all 200
  Admin   pages 1 and 2 -> 400 {"code": 104, "title": "Read failed for entity type [Page]", "source": null, "detail": null}
          pages 3 and 4 -> 200; the same rows without that field -> 200

as the Artist, another user's override:
  GET /entity/page_settings/<id> -> 200, settings_json a list
  _search [["user", "is_not", null]] -> 200, 28 rows: every user-owned row on the site

Teaches

The script user does not see every page. Every other count in this corpus is an api_admin number and the widest read on the site (probe 027); on Page an Admin reads 941 more, 41 of them unshared. To list the pages a person sees, read as that person with sudo_as_login; the script's list is neither a superset nor theirs.
A page the script cannot see answers 404 by id, and its PageSetting rows do not come back under page in [...] either.
On the probed site the Artist reads no project page at all and 107 site-level ones, so a Page+ list for an Artist is empty for projects even where probe 027 shows that Artist reading 8 projects.
current_user_can_see can fail a whole read. As an Admin, asking for it in fields turned two pages of 500 into 400 code 104 Read failed for entity type [Page] with detail null, and the same rows read fine without it. Leave the field out of listings; read it per page if it matters.
Overrides are not private over REST. A person reads every other person's PageSetting row, by id and by _search, so a column layout is visible site-wide.