Read a compact source-linked brief or incremental observations

Public edition window only. The default balanced mode returns a bounded five-story snapshot diversified across category, event class, and publisher, with a resumeCursor but no page cursor. That checkpoint continues as a complete chronological change stream, including when a client repeats mode=balanced. chronological and all preserve the complete sequence order: nextCursor pages through unread results and resumeCursor marks all matching observations visible at response start as caught up. Stable IDs identify exact normalized content, not inferred global events.