dbt Charts gives agents a validate step with named warning codes before a chart is rendered
dbtcharts.com·low signal
Charts are declared in YAML wrapping SQL, where SQL says what data and YAML says how to see it, and `dct validate` checks both YAML syntax and SQL correctness before anything renders. The part worth stealing is the pre-render warning vocabulary, codes like WARN-BAR-BAND-WIDTH-TOO-NARROW and WARN-TABLE-COLUMNS-OVERFLOW, which gives a generating agent a machine-readable correction signal instead of a silently ugly chart. Boards live in the same repo as the dbt models, so CI validates them, and one definition renders to SVG, HTML, PNG, PDF or terminal.