9e551d2931
Per review: existing providers should not be retroactively re-versioned or handed a changed payload. Version 1 is now the implicit historical on_pre_compress() contract (best-effort, raw message list) that every pre-existing provider is already on; the fail-closed checkpoint contract becomes version 2. MemoryManager routes the raw transcript to v1 providers unchanged and hands the host-normalized evidence list only to v2+ checkpoint providers, so the plugin surface contract for shipped providers is byte-identical with the gate off.