explain_cost_change

com.plutus-cloud/plutus-cost-data · Verify this server

Explain a specific cost change: which timeline events line up with it, how strongly, and how much of the move Plutus could account for. Ask this about any point on a cost chart — it is not limited to anomalies the detector flagged (use list_anomalies for those; each already carries the same explanation). RENDER `explanation.sentences` AS WRITTEN. They are generated under a strict discipline and are the only phrasing this data supports: Plutus reports temporal and dimensional evidence, never causation. Each candidate carries a `claim` of "coincides" (temporal proximity only — the common case), "consistent_with" (proximity plus a confirmed link between that event source and this cost entity) or "accounts_for" (a known dollar amount that matches the move). Do not upgrade one to another, do not say an event "caused" or "led to" the change, and do not merge several candidates into a single narrative. Three separate numbers, never interchangeable: `change_evidence` is how sure we are a real change-point exists at all; `attribution_completeness` is what fraction of the move was localized to a specific part of the bill (a low value means "we do not know what this spend is yet", which is NOT the same as "nothing explains it"); `p_cause` is per candidate, and sums with `p_unknown` to 1. `tier: "unknown"` means we looked and found nothing that lines up — say that, rather than reaching for the top-ranked candidate anyway. Confidence is capped at 0.60 by design; there is no "high" tier today. Body: `dimension` + `value` name the slice (e.g. service=AmazonEC2), optional `cost_source_id` narrows it, and exactly one of `day` or `range` says when. A range is narrowed to the single biggest-moving day inside it, reported as `explained_day`. Mirrors POST /api/accounts/:accountId/cost-changes/explain.