Feature request: agent-emitted images inline in assistant messages (assistant-side rendering)

[usavv1547-cyber]

Summary

Allow the agent (assistant) to include images in its replies so they render inline in the conversation — e.g., charts/plots produced by the agent (matplotlib PNGs), diagrams, or screenshots of results. Today the protocol already reserves this, but nothing wires it end-to-end.

Why it matters

Agents routinely produce visual artifacts (backtest charts, data plots, architecture diagrams). Right now the only way to show them in the Web UI is a clickable file link, or a fragile workaround: serving the file from a local HTTP server and embedding a markdown image (http://127.0.0.1:PORT/x.png) — which only works because the markdown image renderer happens to allow http(s) URLs.

What already exists (verified in the current code)

1. Protocol — ImageBlock (type: 'image', attachment: ImageAttachmentRef) is already part of ContentBlockMap in packages/llm. The type comment explicitly says:

   "A durable raster image reference, valid in user or assistant content. The block is deliberately role-neutral; assistant-side rendering is forward compatibility — the current production adapters declare text-only output, so only user content carries images today."

2. Storage — dsh-attachment defines the durable attachment vocabulary and limits (maxImageBytes, maxImagesPerMessage, maxImagePixels, media types); dsh-attachment-local implements it.

3. UI components — dsh-client-ui-attachment already ships MessageImage / ImageGallery / ImageLightbox, keyed by attachment.attachmentId (currently used for user uploads).

What's missing

1. An agent-side channel to persist an image into the attachment store and emit an ImageBlock in assistant content (adapters currently declare text-only output).
2. Rendering of ImageBlock inside assistant message content in the conversation UI — the markdown renderer only handles ![]() images, and its URL sanitizer allows only http:/https:/mailto: (so data: URLs are rejected).
3. Session log / export support for image blocks (or graceful degradation).

Suggested minimal path

• Add a small tool/API for the agent to save an image (reuse SaveImageAttachment) and receive an ImageAttachmentRef to embed.
• In the message renderer, map ImageBlock → the existing MessageImage component, mirroring the user-side path.
• Handle image blocks in compaction and log export, or degrade gracefully.

Happy to iterate on the design if this aligns with the roadmap. Thanks for the project!