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Breaks a Smart+ ad (or ad group) down by creative material, one row per Spark post, video or image, from TikTok's Smart+ material report. For a Spark post `tiktokItemId` is the TikTok post id. Conversion metrics are TikTok web (pixel) events. `purchases`, `purchaseValue` and `roas` come from Complete Payment, or from Place an Order (legacy ON_WEB_ORDER pixels) when that reports more; the two are never summed. TikTok allows two dimensions per report, so rows are keyed by the Smart+ ad (`level=ad`) or by the ad group (`level=adGroup`), not both. A row is identified by `smartPlusAdId` + `materialId` at `level=ad` and by `adGroupId` + `materialId` at `level=adGroup`; each appears once across all pages. Rows are sorted by `spend` descending, then the Smart+ ad or ad group id, then `materialId`, and the full result is cached for 10 minutes per account, advertiser and query, so pages read within that window are consistent and `totalRows` counts distinct rows. When the result spans more than one TikTok page it is read per Smart+ ad (or ad group) listed on the advertiser, every status included, and those reads can return more rows than TikTok's unfiltered report declares, so `totalRows` can be larger than that count; when the unfiltered report fits one page (100 rows or fewer) it is served as is. Each TikTok read is checked against the row count it declares itself, and a short read is retried once. A shortfall of at most 2 rows (or 1% of the rows, whichever is more) is served with `missingRows` set to that number; a larger one answers 502 instead of a short result. Metrics TikTok returns empty come back as null.