Second alignment step for #2248: document-level drag intake behind the new
DropOverlay atom, lightbox close icon and shared dialog mask, DeepSeek Chat
thumbnail rules (single 240px long edge with ratio clamp, 64px tiles, merged
consecutive assistant images), image limits raised to 20/10MiB/100MiB and
published to clients as the imageLimits projection, whole-batch intake
pre-check with product-copy banners, and attachment-error reasons mapped to
localized copy.
Single-click original preview in the composer rail and chat history; remove
control inside the thumbnail, revealed on hover/focus (always on touch);
hidden-scrollbar rail overflow paged by edge arrows with wheel panning and
end-reveal on add; image-intake rejections and prompt failures announce as a
transient top-center toast instead of inline strips.
The attachment atoms move to a new zero-cordis package
@deepseek-ai/dsh-client-ui-attachment (rail, message gallery, lightbox),
seeded as a platform module; the toast is a ui-primitives atom. Strings
arrive as label props bridged from the conversation dictionary.
creatixchu