Summary

This pull request adds the app_context_changed event type to @slack/types. The event fires in the agent DM (agent_view) experience when the user's surrounding context changes (e.g. they navigate to a channel, canvas, list, or message).

• Adds AppContextChangedEvent to the SlackEvent discriminated union, covering the context entity kinds: slack#/types/channel_id, slack#/types/canvas_id, slack#/types/list_id, and slack#/types/message_context.
• Adds an app_context field to GenericMessageEvent, since the same context is delivered inline on messages.

Scoped to the type definitions only — handling the event is left to consumers (e.g. Bolt and the sample apps).

Testing

Subscribe to the event and let TypeScript narrow each entity by its type:

app.event('app_context_changed', async ({ event }) => {
  if (!event.context.entities) return;

  for (const entity of event.context.entities) {
    switch (entity.type) {
      case 'slack#/types/channel_id':
      case 'slack#/types/canvas_id':
      case 'slack#/types/list_id':
        console.log(entity.type, entity.value); // value: string
        break;
      case 'slack#/types/message_context':
        console.log(entity.value.message_ts, entity.value.channel_id); // value: { message_ts, channel_id }
        break;
    }
  }
});

Requirements

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.