Opaque provider payload (Anthropic compaction block(s) / OpenAI compaction item). Never interpreted outside the originating backend.
Originating provider tag, e.g. 'anthropic' or 'openai-responses'.
Optional
Human-readable summary, when the provider exposes one.
Opaque provider payload (Anthropic compaction block(s) / OpenAI compaction item). Never interpreted outside the originating backend.