plot-type-check

name	plot-type-check
description	Gate that a plot type is correctly implemented in RING-5 — BasePlot contract, engine-agnostic traces, PlotFactory registration, dual-engine render, config UI, serialization. Use to verify a new/changed chart type before merging (complements the add-plot-type build skill).

Plot-type check (the chart conformance gate)

A plot type is correct only if it is engine-agnostic and fully wired. To build one use the add-plot-type skill; this skill verifies the result. Types live in src/web/pages/ui/plotting/types/; the registry is src/web/pages/ui/plotting/plot_factory.py::PlotFactory.

Checklist

1. BasePlot contract — the class subclasses BasePlot and implements both abstract methods:
   • create_traces(self, data, config) -> TraceBuildResult
   • get_legend_column(self, config) -> str | None create_figure() is inherited — only overridden with good reason. (GroupedStackedBarPlot extends StackedBarPlot, not BasePlot directly — that's allowed.)
2. Engine-agnostic — the plot builds TraceConfig/TraceBuildResult only. No go.* and no plt.* inside the plot class. Styling is not the plot's job (it lives in FigureConfig + the connectors — see rendering-figureconfig).
3. plot_type set before super().__init__ in __init__.
4. Registered (snake_case) — present in PlotFactory._plot_classes with a snake_case key (grouped_bar, not groupedBar — shapers use camelCase, plots use snake_case) and a matching _plot_metadata entry (display_name, icon, category ∈ basic|comparison|distribution).
5. Exported from src/web/pages/ui/plotting/types/__init__.py (so registration runs).
6. Dual-engine — renders under both Plotly and Matplotlib (toggle ring5_engine_mode); the trace converters are trace_to_plotly.py / matplotlib_trace_renderer.py.
7. Config UI — if it needs options beyond the shared X/Y/color selectors, a component under src/web/components/plotting/config/ is wired via plot_config_ui.py/PlotConfigUIMixin, with per-plot-unique widget keys f"{prefix}_{field}_{plot_id}".
8. Serialization round-trips — BasePlot.to_dict/from_dict + PlotFactory rebuild it; any new state is plain/JSON-serializable so portfolios survive save/load.
9. Conventions — default palette wong; error-bar column is {y}.sd.
10. Coverage — there is a unit test exercising create_traces/create_figure with sample_data. dual_axis_bar_dot is WIP and intentionally excluded from coverage — don't count it as a model.

# registry sanity
grep -n "_plot_classes\|_plot_metadata" src/web/pages/ui/plotting/plot_factory.py
# engine-leak smell (should be empty inside types/)
grep -rn "import plotly\|plotly.graph_objects\|matplotlib\|plt\." src/web/pages/ui/plotting/types/

Keep this skill sharp

Canon, not history — edit in place when the plot contract moves:

• The abstract methods and registry shape above mirror base_plot.py and plot_factory.py. If a new abstract method is added or the metadata schema changes, update this checklist.
• New conformance failure caught in review? Add it here (and to add-plot-type if it's a build step); durable facts → a memory.

Verify after

make arch-check && ./python_venv/bin/mypy src/ && ./python_venv/bin/pytest tests/unit -k plot -q