Data Import & Validation (Streaming + Error CSV + Metrics + Idempotency) When to use this skill Use when working on: - ETL / import pipelines (CSV/XLSX/JSON) into a DB - Parsers that currently load whole files into memory - Data validation/coercion, error isolation, auditability, and reproducibility - Any import job that must be safe to re-run (idempotent) Non-negotiables (contract) 1) Process input files sequentially (no “load everything then insert”) to control memory. 2) Validate and coerce types explicitly (define allowed coercions; reject ambiguous cases). 3) Irreparable records must be…