Chat¶

Introduction¶

The Chat method group lets a Product participate in the Polkadot App's chat surface by registering as a bot in a room, publishing typed messages, and rendering custom message types that the App displays inline. The underlying transport composes the Statement Store for signaling with the Bulletin Chain for content that has to outlive the gossip time to live (TTL). The Chat group exposes a higher-level surface on top of that pattern.

For the conceptual model of how Chat composes the two layers, see the Chat in the Polkadot App reference. This page documents the TrUAPI surface that powers it.

Conceptual Contract¶

Methods in this group fall into three families:

• Room and bot registration: A Product registers as a bot inside a room and creates simple group chats via host_chat_create_simple_group, introduced in v0.2. The registration call is gated by the standard Permissions surface.
• Publishing typed messages: The Host accepts Text, RichText, Actions, File, Reaction, and Custom message types. It handles encoding, attaches the per-Product account context, and dispatches to the Statement Store and Bulletin Chain underneath.
• Custom-message rendering (reverse subscription): product_chat_custom_message_render_subscribe lets the App ask the Product to render its own Custom message types in place. The Host opens a subscription against the Product, and the Product responds with rendered output for each message it owns.

Messages a Product submits before bot registration completes are queued automatically. The Product does not need to track registration state.

Where to Go Next¶