Optional client/conversation identity for one additional message cache. An empty value disables its use without evicting it (for summaries). Reuse requires the same scope and an exact token prefix on this model and device. A different nonempty scope discards the previous user's checkpoint. Only complete input frames are saved, never generated text. Calls remain serialized on the inference owner. Additional sequence storage on the selected device lasts until clearContextCache() or close().

provider.contextCacheScope = clientId+":"+conversationId