Dsh-ImageProview

In a dsh chat session, images the agent reads via read_image tend to vanish silently. The official UI classifies those messages as context nodes, which have no image seat, so only a path string survives. To make matters worse, read_image itself only accepts PNG, JPEG, WebP and GIF, meaning anything the agent produces in HEIC, TIFF, PSD, SVG or other formats never even becomes an attachment. Dsh-ImageProview was built to close that gap.

The plugin adds two kinds of image nodes to the chat flow. The first handles agent image attachments from read_image, reusing the durable attachment store with zero extra I/O. The second handles image files merely named in a message, fetching them on demand through the host route and rendering them in place. Rendering is delegated entirely to the official renderMessageImages pipeline, so thumbnail sizing, load and retry states, and the full-size lightbox are all native ui-attachment behaviour. No official component is overridden or reimplemented. Format coverage is broad: PNG, JPEG, GIF, WebP, AVIF, BMP, ICO and SVG are served byte-for-byte; HEIC, TIFF, PSD, JP2, TGA, Netpbm, EXR and JXL are transcoded to PNG via a sips, ImageMagick, and ffmpeg chain, with built-in zero-dependency TGA and Netpbm decoders as a fallback. Refreshing the page lights up past sessions too, because the projection is rebuilt from the session log.

This plugin is for developers whose dsh agent pipelines produce or reference images in non-standard formats, and for anyone who wants to see what the agent drew without switching to a file manager. On the security side, cross-site requests are refused by default, realpath is validated against an allow-list, and leading-byte sniffing rejects a shell script masquerading as a PNG.