Mention your other models with @

Most of what I build is a variation of something I already built. A phone stand, then the same stand on a plate. A box, then a lid for that box. Until now the chat had no memory of your other models: you either described the first part all over again (and got a slightly different one back) or downloaded the file and uploaded it into the new chat.

Now you type @, pick the model, and the agent gets the real thing.

One real run

I had a phone stand from an earlier chat, 70 mm wide with a 12 mm lip. I wanted it on a square base with a cube next to it, mostly as a test of whether the agent would leave the stand alone.

In a new chat I typed "Put @", picked "Simple Phone Stand" from the list, and finished the sentence: "on a 100 mm square plate with a 20 mm tall cube beside it. Keep the stand exactly as it was."

The first thing the agent did was open the mentioned model. It got the stand's file, the OpenSCAD code that built it, and its seven parameters (width 70, lip 12, base depth 80 and so on). Then it wrote a Blender script that imports that file untouched and adds a 3 mm plate and the cube around it. Its reply: "the original stand is unchanged, placed on a 100 × 100 mm plate with a 20 mm cube beside it."

That's the point. It didn't build a new phone stand from the words "phone stand". It used mine.

How to mention a model

Type @ anywhere in the message box. A list of your models opens, newest first, each with its thumbnail. Keep typing to filter by name ("@pho" is enough for "Simple Phone Stand"), move with the arrow keys, press Enter or Tab to insert. On a phone the list opens above the message box and you tap the model.

Two more ways in:

• The "…" menu left of the message box has a "Mention a model" item, which types the @ for you.
• Paste a link to a GrandpaCAD chat (the address of any of your models, or a public /view/chat link) and it turns into the mention by itself.

The list puts models you've mentioned before near the top, then models from the workspace you're in, then the rest by date. Delete the @Name text from your message and the mention goes with it, so the agent never gets a model you took out of the sentence.

What the agent gets

A mention isn't a screenshot or a summary. When the agent opens a mentioned model it receives:

• the current file (3MF, STL, GLB...) as a URL it can pull straight into the build;
• the tool call that produced that file, source code included, so it can read how the part was made and reuse the approach;
• the model's parameters with their current values, and the last thing you asked for in that chat;
• links to up to eight earlier files from the same chat (file and format only, no code), in case the latest one isn't the one you meant.

Opening a model costs nothing; it isn't a generation. The build that follows is a normal one.

What it does with all that depends on what you ask. "Keep it exactly as it was" means it imports the file and models around it. "Make the same thing 20% wider" means it adapts the code, because a mesh can't be stretched without ruining the details. "Match the hole pattern" means it reads the numbers out of the source. Among the steps in the chat you'll see "Opened @Name", and the chip links back to the original, so you can always check which one it used.

Who can mention what

You can mention any model in a workspace you belong to, your teammates' models included, and any model that's been made public. Nothing else. A link to someone's private chat stays a plain link, and if the agent ever asks for a model you can't see, it gets a "not available" answer instead of the model.

A few things to know

• A mention points at a chat and opens whatever that chat's latest model is. Change the original later and a new mention picks up the new version; the models you already built from it stay as they are.
• Slider changes in the new chat don't reach the mentioned model. Its parameters came along as plain numbers.
• Editing a sent message keeps the mention as long as the @Name stays in the text.
• Mentions are a web chat feature for now. The MCP connection for ChatGPT and Claude doesn't have them yet.

Try it on something you already made

Open a new chat, type @, and pick the last thing you printed. Ask for the lid, the wall mount, the two-up version, the one with your name on it.