Jadpo is experimental and not ready for production. These docs follow the compiler's main branch as of 5 Nov 2026. What's built · Install 0.3.0

ReferenceErrors

Errors Reads and writes · rule

`data.patch_overlap`

Supplied-field block sets a field the patch already sets.

Area 6, Reads and writes; not declinable; the next step is usually the agent's.

example

type ItemName = Text {    max_length: 80}entity Item {    id: Uuid    name: ItemName    nickname: ItemName?}type ItemChanges = Input {    pick: [Item.name, Item.nickname]    optional: all}action edit(item: Item, amendment: ItemChanges) -> Item {    return Item.update(item) {        patch: amendment        when_supplied: {            name: {                nickname: none            }        }    }}

jadpo checkcheck failed: 1 error, 1 file

error nickname is set by the patch and by when_supplied:

--> main.jadpo:21:17

   |21 |                 nickname: none   |                 ^^^^^^^^ set twice

reason: ItemChanges supplies nickname already, so a value here would compete with the request's.
next: Remove nickname from when_supplied:, or from ItemChanges (agent)
rule: data.patch_overlap
help: https://jadpo.dev/docs/errors/data.patch_overlap

Markdown for agents: /docs/errors/data.patch_overlap.md.Built from Jadpo main at aee2e8f.