DataRef kinds

Where in the UI. Layout value source, fieldBindings, editFilter watches, action targets.

Kind	Points at	Store	Read/write
`itemField`	Built-in item column	Current item’s SQLite/row fields listed in Item fields.	Read/write except createdAt (read-only).
`indexedItemField`	imageUris[n]	Nth gallery photo on the item.	Write replaces that slot.
`categoryProperty`	Category value	Property owned by a category. Must use the owning categoryId. Optional itemFrom itemVariable to read another item.	Read/write if scriptWritable allows writes from scripts.
`computed`	Computed definition	Named derived value on the template.	Read-only.
`localState`	Session slot	Temporary key for the open session.	Read/write; not persisted as item data.
`runtimeContext`	Host context	currentDateTime, currentUserId, privacyLevel, authState, canvasScale, canvasMode, colorScheme.	Read-only.
`itemMetric`	Lazy metric	Counts and flags (children, images, graph degree, fill rates, descendant timestamps…).	Read-only.
`expression`	Expression library	Evaluate another named expression.	Read-only result.
`itemVariable`	Item variable	Key in itemVariablesJson. Scripts create/update keys.	Read/write via scripts and some bindings.
`themeColor`	Theme token	App chrome or item-default theme colors, with auto/light/dark mode.	Read-only.
`itemHasClass`	Membership	Whether the item (or ancestor) has a class.	Read-only.
`itemHasCategory`	Membership	Whether the item has a category id.	Read-only.
`itemHasElement`	Membership	Whether the item’s element id matches.	Read-only.

Localized template strings are not a DataRef. Button labels, Containd text in Blockly, and chrome copy live in the translations matrix. You bind fields and properties; you translate strings. Source: containd/.../v2/types/binding.ts DataRef.