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Undo, pivots and images with an agent

An agent joined to your session (Build with an AI agent), Claude on claude.ai (Use theprototype from claude.ai and voice) and the in-app Assistant can take back their own steps, set the point a thing turns about, and put images into your library.

Every call works like the agent's other tools: everyone in the session sees the change at once, one call is one undo step (Ctrl+Z, or Undo on the call's line in Agent activity), and a viewer's agent cannot use the tools that change things.

Try it

Templates ▸ Agent workshop opens a plain room (a floor, a table with a lamp, a crate, a ball and a door). Ask for a curvy vase on the table, a handrail along the edge, a star-shaped sign above the door, a wood floor or a glass ball, then say "undo that". While Claude is connected, the Connect Claude row says so until it has used one of these tools.

Undo that (undo_last)

undo_last takes back the agent's own last call, or its last few with count (up to 20, newest first). It never touches anybody else's work. If someone has changed the same objects since, it changes nothing and says who changed what, so the agent can tell you instead of undoing over your edit. Selecting an object is not editing it: an object you only have selected does not stop the undo.

On claude.ai and in voice mode, "undo that" or "take that back" calls it. In the in-app Assistant one prompt is one step.

The point a thing turns about (set_pivot)

set_pivot sets the point an object turns and scales about, without moving it: a head that nods at the neck, a lamp that tilts at its joint, a door on its hinge. It is the same setting as the Inspector's Origin rows.

  • at: a point in the world, in metres · local: a point in the object's own space · preset: bottom, center, median, world or children · reset: true: back to the object's centre.
  • After it, the agent's rotate and scale, animation clips and Spin / Orbit nodes all turn the object about that point. The scene list shows it as pivot.
  • Up to 100 objects in one call. A position given in the same change is taken as written.

Several parts on one joint (create_pivot)

create_pivot makes a group at a point and puts objects in it, so turning the group swings them all about that point: the parts of an arm about a shoulder, a shade and a bulb about the lamp's joint. at is a point or center, bottom or top of the objects together; the objects stay where they are. Objects that share a parent group keep it (the pivot goes inside). Up to 500 objects.

Since 1.59 the point can also be local: [x, y, z] in the space of the group the objects are already in — the numbers list_scene shows inside it (at the top of the scene that is world space). That is the easy way for parts an agent built inside a group.

Images into the library (add_image)

add_image puts one image into the shared library and returns its hash, which a texture slot takes (set_material, or a material's map). Give exactly one source:

  • url: an https address. The site must allow other origins (CORS), and addresses on your computer or your local network are refused, also after a redirect. It gives up after 20 seconds.
  • data: base64, or in parts with chunk. This is how an agent passes an image it generated or has on its own machine.
  • canvas: an image the agent describes: rectangles, circles, lines, text, gradients, checkers, stripes and seeded noise. Good for textures, signs and labels.

PNG, JPEG, WebP, GIF (the first frame) and AVIF are taken; SVG and HEIC are refused. Limits: 16 MB in, 40 megapixels, 4096 pixels on the long side (larger is scaled down), a canvas 2048 pixels and 500 steps. Only the pixels are kept: the image is redrawn and saved again, so location data and anything else inside the file is gone. The same rules apply to an https texture given to set_material.

Cookbook

  • A nodding head: set the head's pivot at the neck (at: [0, 1.5, 0]), then rotate it or give it a clip.
  • A tilting lamp: create_pivot with the shade and the bulb at bottom, named Lamp joint; rotate that group.
  • A wood-ish floor from nothing: add_image with a 512 × 512 canvas of brown noise and faint stripes, then put the hash on the floor's material.
  • "Undo that": the agent calls undo_last; if it refuses, it tells you who changed what instead of trying again.

On claude.ai these tools are reached through the connector's tool families: edit_shape (pivot, pivot_group), assets (image), and undo_last as itself.