Support custom payload fields in the agentcore dev Web UI

[ohinhyuk]

Description

Thanks for building AgentCore — it’s been really helpful for developing and running AI agents.

The agentcore dev Web UI currently seems to support only a session ID and prompt.

It would be useful to also provide custom request context. For example:

{
  "prompt": "Why did this change?",
  "context": {
    "current_menu": "sales_forecast",
    "reference_date": "2026-08-01"
  }
}

In real applications, agents often need request-specific context such as the current page/menu, reference date, selected item, or filters. This context can change between requests, so a session ID alone is not enough.

Currently, this can be tested by calling /invocations directly, but not through the dev Web UI.

Would it be possible to add an optional JSON payload/context editor to the agentcore dev Web UI?

Thanks again for all the work on AgentCore!

Acceptance Criteria

• The agentcore dev Web UI allows users to provide additional custom JSON fields alongside the prompt.

Additional Context

No response