JSON-encoded canonical filter list. On trace, span, session, graph, and eval-task bounded reads, created_at/start_time datetime filters support equals, greater_than, greater_than_or_equal, less_than, less_than_or_equal, between, not_equals, not_between, is_null, and is_not_null. Missing bounds retain the finite default window: 30 days ago for the lower bound and request-time now for the upper bound. Between and not_between use half-open [start, end) ranges; not_equals excludes one DateTime64(6) microsecond. Because the physical created_at/start_time field is non-null, is_null returns an exact empty result without a ClickHouse read and is_not_null preserves the base window. Valid contradictions also return an exact empty result.

Zero-based numbered page. Pages whose required ordered work exceeds the finite read contract return HTTP 422 with code page_depth_exceeded; request an earlier page or narrow the time range.

Opaque continuation token returned by the previous page. When supplied, do not also send the numbered-page parameter.

JSON-encoded list of custom attribute keys to hydrate; only requested keys are returned. Each key resolves to its latest live span value by (start_time, span_id). Comma-separated simple keys remain supported.

Omit for backward-compatible complete bounded pages, which may label total_rows as a lower bound. Send false to require an exact total. Send true to opt in explicitly to lower-bound totals and, on the first page, a clearly labelled bounded partial result when the full ordered prefix cannot be proven inside the read budget.