calculated: Flow PT field type reference

Data type calculated. Read, write and clear probed on Task.workload (stock, editable: false), sort and _summarize on all four fields the site has:

entity	field	`calculated_function`	`renderer`	reads back as
Task	`workload`	`{duration}`	`duration`	`3000` (int, minutes)
Task	`workload_per_day`	`to_days({workload})/ceiling(to_days({duration}))`	`float`	`"0.972222"` (str)
Task	`workload_per_day_per_assignee`	`{workload_per_day}/{workload_assignee_count}`	`float`	`"1.0"` (str), null on 21 of 40 rows
Asset	`sg_calculated`	`CONCAT({code}, {id})`	`text`	`"charA1,226"` (str)

Version, Shot, Project, Sequence, Note, PublishedFile and Playlist have none; their computed columns are summary and pivot_column. None is editable here, and POST /schema/<Type>/fields answers the type with a 500 (probe 019): one exists because the web interface made it, or not at all.

operation	outcome
read	plain value in `attributes`
create or update	400 code 103 `API update() Task.workload is read only.`
clear	400, same string
filter, any relation	400 `API read() Task.workload's 'calculated' data type cannot be used in a filter.`
sort, `_search` on all four fields, `GET` on `workload`	200, on the computed value
`_summarize`, sum, count and grouping, all four fields	200

GET /schema/Task/fields/workload returns exactly four properties:

property	value on `Task.workload`	`editable`
`calculated_function`	`{duration}`	true
`renderer`	`duration`	true
`summary_default`	`sum`	true
`default_value`	`null`	false
the field's own `editable`	`false`	false

The result data type is never stated: renderer is the only declaration, and its values are not data_type values.

The value is read-only, the definition is not. PUT /schema/Task/fields/workload with {"properties": [{"property_name": "calculated_function", "value": "{duration}"}]} returns 200 and the full field record. The value sent was the one already there and no row was read back under a changed formula, so the 200 is all that is established. The schema names entity_type and no project, so a rewrite that takes effect changes every row of that type; settling that needs a disposable site and one row read before and after.

Read A plain value in attributes, never relationships (relationships is {} on a Task), returned when named in fields and in fields=* (37 of 56 Task attributes). The shape follows renderer, not the operands:

`renderer`	JSON shape	example
`duration`	int, minutes	`workload` 3000, matching `duration` 3000
`float`	string, 6 decimals	`"0.972222"`, `"1.0"`, `"0.625"`
`text`	string, numbers formatted	`"charA1,226"` for id 1226

PUT {"duration": 480} then reading the row back returns workload: 480 on the next request, through both GET /entity/tasks/<id> and _search; duration: null returns workload: null.

Write Every form tried on Task.workload, on a throwaway sandbox Task:

sent	result
`POST /entity/tasks {"workload": 480}`	400 `API create() Task.workload is read only.`
`PUT {"workload": 480}`	400 `API update() Task.workload is read only.`
`PUT {"workload": "480"}`	400, same string
`PUT {"workload": "{duration}*2"}`	400, same string

Every refusal, the POST create included, returns code 103 and source: {}, and the row reads back unchanged. Match on status and code: 103, not on source, which a type error fills with the field name. Nothing is accepted and discarded, unlike cached_display_name: editable: true, a 200, value dropped (probe 004).

Clear

sent	result
`null`	400 `API update() Task.workload is read only.`
`""`	400, same string
`0`	400, same string

The value stays whatever the formula computes. To empty one, write null to the field its formula reads: {"duration": null} gives workload: null, changing the operand too.

Filter No relation is accepted, and none is enumerated the way probe 017's types are:

["workload", "definitely_not_an_operator", null] -> 400
 title:  "API read() Task.workload's 'calculated' data type cannot be used in a filter."
 source: {"Task.workload": " data type cannot be used in a filter. Value: {"path" => "workload",
          "relation" => "definitely_not_an_operator", "values" => [nil]}"}

filter	result
`is` null, `is_not` null	400, same string
`is` 0, `is` 480	400, same string
`greater_than` 0, `less_than` 100000, `in` [480]	400, same string
any of the above on `workload_per_day` or `Asset.sg_calculated`	400, same string

Sorting and summarizing work, on the computed value:

call	result
`_search` `sort` `workload` / `-workload`, and `GET ?sort=-workload`	200, first 5 `[0,0,0,0,0]` / `[6000 x5]`
`sort` on `workload_per_day`, `workload_per_day_per_assignee`, `Asset.sg_calculated`	200 both ways, and the order reverses: `"0.625"` first ascending, `"1.0"` first descending
`_summarize` sum(`workload`) / sum(`workload_per_day`)	200 `{"workload": 5676600}` / `{"workload_per_day": 1677.978125}`, a number where the read is a string
`_summarize` grouping exact on `workload`	200, `group_name` `"1.25 days"`, `group_value` `"600.000000"`, 11 groups
`_summarize` grouping on `workload_per_day_per_assignee`	200, 8 groups, `group_value` `"0.892857"`
`_summarize` count and grouping on `Asset.sg_calculated`	200, `{"sg_calculated": 801}` and 801 groups

Traps

Filter it by rewriting the formula. ["workload", "is", 600] 400s; ["duration", "is", 600] gets the same rows for {duration}. There is no equivalent for CONCAT({code}, {id}): page and match client-side.
Sort is the one query verb that survives: top-N by a computed column is one call, on all four fields.
A float renderer returns a string, so sorted(rows, key=...) on the raw value sorts lexicographically and puts "0.9" after "0.625". Cast before comparing (field_types/float).
A text renderer formats numeric operands for display: CONCAT({code}, {id}) on id 1226 gives "charA1,226", a thousands separator inside a string a client might parse back.
Division by null yields null, not an error: workload_per_day_per_assignee is null on 21 of 40 rows where {workload_assignee_count} is 0. Fill rate measures the operands, so drop the type from fill ranking (probe 007).
default_value is present in properties and always null. Nothing sets it; do not read it as the value of an unpopulated row.