An AI agent is the assistant you chat with in an AI app such as Claude or ChatGPT. Once you connect the app, the agent works on the same saved projects you edit in the builder. It does not need the builder to be open.
What it may do depends on the two permissions you gave its app on the consent page, Build and Publish. An app has one of them or both, never neither, and they cover every project you own.
What every connected app can read
Whichever permission it has, a connected app can read your plan, how many projects you use and your limits. It can list your projects and see the names of each one's templates, sections, layouts and patterns. It can also see whether a project is connected to a Ghost site, and the copy of that site's posts and tags that the builder's preview uses.
With Build
An agent with Build does most of what you do in the builder:
Create, rename, duplicate and favorite projects, move them to the trash or back, and delete a project in the trash for good.
Change templates, layouts, sections and blocks, patterns, custom blocks, and the variants and formats that set how blocks such as the Button look.
Change Styles, such as fonts, colors and spacing, and Project settings, such as custom code and redirects.
Search the built-in patterns by what a section should do, and check its own work for problems such as text that is hard to read on its background, demo pictures or demo text left on the page.
Reset a project, a pattern or a block's look to how it came.
Upload images, write their alt text, and delete them.
Add Google fonts, upload fonts, and remove them.
See and delete the versions in History.
On Pro, save a version, restore one, and download the theme file.
Before it changes the design, the agent reads the project's agent instructions and follows them, then Fantasma's design advice for agents. The agent reaches the same limits as you, and a block goes only where the builder would let you put it. It cannot use your selection on the canvas, your clipboard or your undo history, so tell it which page and which section you mean.
With Publish
An agent with Publish can:
Connect a project to your Ghost site, replace that site, remove the connection, and check it.
Refresh the copy of your Ghost posts that the preview uses.
On Pro, publish the theme to the connected Ghost site.
Submit a project to the Community Gallery, or withdraw it.
To connect a Ghost site, the agent asks you for your Admin API key or Staff access token in the chat, and Fantasma stores it with the project. To keep the key out of the chat, connect your Ghost site yourself in Project settings › Ghost. That article also shows where Ghost Admin keeps the key. The agent then publishes over that connection.
What the agent asks you first
Before some actions, Fantasma tells the agent to name the project and what will happen, and to wait for your yes in the chat:
Publishing a theme to Ghost.
Connecting a project to a Ghost site, replacing that site, or removing the connection.
Deleting a project from the trash for good, or deleting an image, a font, a saved version or an agent instructions file.
Restoring a version, which replaces the project's content.
Resetting a project, a pattern or a block's look.
Submitting a project to the Community Gallery or withdrawing it.
Fantasma shows no approval screen of its own for these. It checks that the agent says you agreed, but it cannot see your chat, so read the agent's question before you say yes. Moving a project to the trash needs no yes, because you can restore it from the trash for 14 days.
Changes go to your project, not your site
Every change an agent makes is saved to your project in Fantasma, the same as an edit in the builder. Your live Ghost site changes only when the theme is published or uploaded in Ghost Admin, or when you upload redirects or routes.yaml to Ghost yourself.
If the project is open in the builder while an agent works, the builder shows the agent's changes when you come back to its browser tab. If you also changed the project in that tab, Fantasma shows "This project was changed in another window", saves your edits as a backup version in History, and you reload to see the agent's version.
What an agent cannot do
Change your plan, start a subscription or cancel one.
Upload redirects to Ghost. You do that in Project settings › Redirects.
Use what your plan does not include. On Free, it cannot download, publish, save a version or restore one, the same as you.
Fantasma tells the agent to change only the projects you ask about, but its permissions reach all of them. Name the project in each request, and leave Publish off when you do not need it, as Change or remove an agent's access shows.
An AI agent is the assistant you chat with in an AI app such as Claude or ChatGPT. Once you connect the app, the agent works on the same saved projects you edit in the builder. It does not need the builder to be open.
What it may do depends on the two permissions you gave its app on the consent page, Build and Publish. An app has one of them or both, never neither, and they cover every project you own.
What every connected app can read
Whichever permission it has, a connected app can read your plan, how many projects you use and your limits. It can list your projects and see the names of each one's templates, sections, layouts and patterns. It can also see whether a project is connected to a Ghost site, and the copy of that site's posts and tags that the builder's preview uses.
With Build
An agent with Build does most of what you do in the builder:
DESIGN.md.Before it changes the design, the agent reads the project's agent instructions and follows them, then Fantasma's design advice for agents. The agent reaches the same limits as you, and a block goes only where the builder would let you put it. It cannot use your selection on the canvas, your clipboard or your undo history, so tell it which page and which section you mean.
With Publish
An agent with Publish can:
To connect a Ghost site, the agent asks you for your Admin API key or Staff access token in the chat, and Fantasma stores it with the project. To keep the key out of the chat, connect your Ghost site yourself in Project settings › Ghost. That article also shows where Ghost Admin keeps the key. The agent then publishes over that connection.
What the agent asks you first
Before some actions, Fantasma tells the agent to name the project and what will happen, and to wait for your yes in the chat:
Fantasma shows no approval screen of its own for these. It checks that the agent says you agreed, but it cannot see your chat, so read the agent's question before you say yes. Moving a project to the trash needs no yes, because you can restore it from the trash for 14 days.
Changes go to your project, not your site
Every change an agent makes is saved to your project in Fantasma, the same as an edit in the builder. Your live Ghost site changes only when the theme is published or uploaded in Ghost Admin, or when you upload redirects or
routes.yamlto Ghost yourself.If the project is open in the builder while an agent works, the builder shows the agent's changes when you come back to its browser tab. If you also changed the project in that tab, Fantasma shows "This project was changed in another window", saves your edits as a backup version in History, and you reload to see the agent's version.
What an agent cannot do
Fantasma tells the agent to change only the projects you ask about, but its permissions reach all of them. Name the project in each request, and leave Publish off when you do not need it, as Change or remove an agent's access shows.
To start, follow Build a theme with an AI agent.