Codex: Document Zookeeper attachment previews and prompt limits

content/pages/docs/zoo-design-studio/features/ml-ai/index.mdx

@@ -22,6 +22,26 @@ Most in-app ML and AI workflows route through
 there for the main user workflow around AI-assisted geometry creation, modification, and design
 reasoning.
 
+When you paste more than 5,000 characters into the prompt, Zoo Design Studio adds the pasted text
+as a `.txt` attachment. Any prompt text you've already typed stays in place, so you can add a short
+instruction before sending.
+
+Before sending, pasted-text attachments show their opening words as a preview. Hover over the
+preview to see the filename.
+
+Image attachments appear as square thumbnails. Before sending, remove an image with the button
+in its top-right corner. Pasted images and viewport screenshots get unique filenames so they stay
+separate across prompts; uploaded images keep their filenames.
+
+Click an image or text attachment to open a full preview before sending or from the conversation.
+UTF-8 text files up to 1 MiB can be previewed, regardless of filename or extension, with their original
+spacing and line breaks; larger files can still be attached and sent. Images fit inside the dialog.
+Restored attachments load when opened, and failed loads can be retried. Press Escape or click outside
+the dialog to close it.
+
+Prompts sent through the API have a 5,000-character limit. Oversized prompts are rejected
+before starting a turn; send larger text as a file attachment.
+
 ## Modes
 
 [Modes](/docs/zoo-design-studio/features/ml-ai/modes) covers Auto, Standard, and Thoughtful modes,