conversation-history-tail-pagination

name	conversation-history-tail-pagination
description	Prevent refresh regressions by paging conversation history from newest entries
domain	gateway-runtime
confidence	high
source	runtime incident: Quill refresh dropped latest turns when history exceeded page size

Context

When chat UIs request only one history page on load (for example limit=200, offset=0), oldest-first pagination can hide recent turns in long conversations. Users perceive this as missing history after refresh.

Patterns

Page from tail by default

• Build the full ordered timeline (oldest → newest).
• Interpret offset as distance from newest entry.
• Compute page window from the tail so offset=0 returns latest page.

Keep chronological order in page

Even when selecting from the tail, return entries oldest → newest inside the page so rendering remains natural.

Guard out-of-range offsets

If offset >= totalCount, return an empty page with the original totalCount.

Examples

var take = Math.Min(limit, totalCount - offset);
var startIndex = Math.Max(0, totalCount - offset - take);
var page = allEntries.Skip(startIndex).Take(take).ToList();

Anti-Patterns

• Oldest-first Skip(offset).Take(limit) for refresh endpoints.
• Returning newest-first arrays that reverse chronology in UI rendering.
• Omitting totalCount, which prevents deterministic paging behavior.