MIME Bundles for Events

Serialize events (especially OutputEvent parts) into JSON-safe MIME bundles for UIs, logging, and replay.

Concept

• render(event) -> dict: canonical, JSON-serializable structure for all events.
• Rich parts converted via _repr_mimebundle_, _repr_html_, _repr_png_, with fallbacks to text/plain.

Example

{
  "event_type": "OutputEvent",
  "agent_name": "data_analyst",
  "parts": [
    {"text/plain": "'Here is the dataframe:'"},
    {"text/plain": "A B...", "text/html": "<div>...</div>"}
  ]
}

Benefits

• Web/UI friendly, observability ready.
• Standardizes multi-representation payloads.
• Graceful degradation with fallbacks.

Considerations

• Truncation and size limits to protect transports.
• Sanitize/escape HTML; base64 encoding for binaries.
• Single implementation used by streamers and hooks.

Related issue: Issue #3