Plotly (Python) — consistent idioms

Plotly is stable, but it offers two APIs and generated code picks the wrong one or mixes them: hand-assembling go.Figure(data=[go.Scatter(...)]) trace loops for charts plotly.express builds in one line, then rebuilding figures to change a title instead of update_layout. The other failure axis is environment: fig.show() in places with no renderer. This skill pins the px-first idiom set for Plotly 5.x/6.x.

Canonical idioms — always X, never Y