Shadcn Message Scroller Load Earlier

When to use

• Chat and assistant transcripts in a bounded panel that open on the newest turn and offer a jump back to it
• Streaming replies that follow the bottom until the reader scrolls up, with sent questions lifted near the top
• Saved threads that reopen at a chosen turn, load older history above the reader or step between questions

When not to use

• The layout of a single turn, its avatar, sender name and timestamp around the body: use the Message component
• A sidebar, settings list or panel that overflows but never grows at the bottom: use the Scroll Area component
• A finished assistant screen with composer, thread list, citations and docked panels: use the AI Chat blocks

Agent notes

• Replace loadEarlier, a 700ms timer that widens the HISTORY slice, with a cursor fetch that prepends older rows
• Keep the load control outside MessageScrollerContent; a permanent first row never moves, so the prepend restore never fires
• Key rows by a stable id, never the index; with index keys the old first row never moves and the prepend restore silently skips
• The parts and hooks throw outside MessageScrollerProvider, so a header or footer control that calls a hook needs the provider above it too
• MessageScroller fills its parent through size-full, so bound the parent height or the page scrolls instead of the transcript
• Render MessageScrollerButton as a sibling of MessageScrollerViewport; placed inside it, the control scrolls away with the rows