Crypto-ETF net flows

Aggregate spot-ETF net flows + per-product breakdown for BTC / ETH / SOL (or ALL). BTC and ETH: Farside Investors is NOT used by this API. The per-fund flow figures Kresmion holds for BTC and ETH trading sessions come from that compiler, which grants no redistribution licence, or from fund-issuer data not yet cleared for redistribution, so every BTC/ETH NYSE-session day is served with total_kind 'withheld', null flow values and withheld_reason 'source_not_licensed'; days with no NYSE session are a genuine zero and are served. Window sums, the 7-day headline, latest_session and per-fund flow_period_usd / flow_1d_usd are recomputed from the served days only, so for BTC/ETH they are null. meta-level flow_withheld says how many days were withheld. Fund AUM, the fund list and the coverage denominators are still served. SOL has no published per-fund flow source, so SOL flows are derived from each fund's AUM/NAV change (AUM from Stock Analysis, NAV and prices from a market-data vendor). Coverage: every day carries total_kind ('total' only when every fund active in Kresmion's fund registry that day is known, 'reported_subtotal' when only some are, 'withheld' as above), funds_known, funds_active, aum_coverage (0..1, null when any active fund's AUM is unknown) and missing_tickers. A day's net_flow_usd is the TOTAL and is null unless total_kind is 'total'; reported_subtotal_usd carries what the known funds add up to. Never present a reported_subtotal as a market total. Note the Grayscale mini trusts trade as BTC and ETH: /etf/history/BTC is that fund, not the asset.