image block

This canonical lookup describes the published image interaction shape, the present renderer support, its return path, and the trust boundary that applies when it is shown to a person.

Type	Contract	Agent may send	Platform may produce	Web renderer	Mobile renderer
image	Published	Allowed	Yes. A person's image/* attachment is stored as an image block the platform constructs itself; the server picks the block type from the asset's stored mime type, never from a caller-supplied field.	ImageBlock	ImageBlockView

image

Allowed

A referenced image asset.

Return path

None; this is display content.

Trust and visibility

The block references an asset id. Clients resolve media through participant-scoped platform URLs, not an agent-supplied URL. An agent-authored reference is checked at write time for image/* mime and for ownership by that agent.

Stability

Available end to end.

Field	Required	Published constraint
type	Yes	literal "image"
asset_id	Yes	string · ^ast_[0-9A-HJKMNP-TV-Z]{26}$
alt_text	No	string · 0–500 characters
width	No	integer · 1–100000
height	No	integer · 1–100000

JSON

{
  "type": "image",
  "asset_id": "ast_01ARZ3NDEKTSV4RRFFQ69G5FAV",
  "alt_text": "Boarding pass QR code",
  "width": 800,
  "height": 600
}

Web preview

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