Goals:

• Extend casts with custom “cast actions”
• Reuse concepts from the existing frames standard where possible
• Keep it simple

Proposal:

• Use frames and frame messages to implement cast actions. A cast action is a frame with no image and one button.
• Install cast actions from URLs with meta tags, like frames.
• Consider extending reactions so actions can persist “receipts” to Hubs.

Implementation

We can reuse the existing frame message format and infrastructure to implement cast actions.

Specifically, a cast action can be implemented as a frame with no image and one button. In the signed message packet, the client can:

• Set frame_url to the cast action URL
• Set button_index to 1
• Set cast_id to the ID of the interacted cast