DannyFengTianYu
07b9090259
Read the durable display transcript when creating a branch instead of copying the compacted model projection. Hydrate the Desktop branch boundary from persisted history, avoid stale whole-chat counts, and seed the new tile from the backend snapshot. Add regression coverage for compacted histories, visible-message counts, selected prefixes, and hydration races. (cherry picked from commit c3d2d759ae104395adde215b2e293ccf8e895684)