gkneighb opened a new pull request, #41860:
URL: https://github.com/apache/superset/pull/41860
### SUMMARY
Adds **histogram** and **box plot** chart type plugins to the MCP
`generate_chart` registry (#39922), extending the creatable chart types from 7
families to 9. These are the first statistical charts the MCP service can
generate — agents doing exploratory analysis previously had no way to look at a
value distribution or compare spreads.
Design notes:
- **Follows the plugin contract exactly**: each type is a self-contained
`ChartTypePlugin` under `superset/mcp_service/chart/plugins/` (schema
pre-validation with LLM-friendly fix suggestions, column-ref
extraction/canonicalization, form_data mapping, name generation), registered in
`plugins/__init__.py`. No registry or core changes.
- **form_data matches the frontend buildQuery contracts** for
`viz_type="histogram_v2"` (single `column` string, `groupby` names,
`bins`/`normalize`/`cumulative` — bins default 5, same as the controlPanel) and
`viz_type="box_plot"` (`columns` = distribute-across values, `groupby` = series
dimensions, `metrics`, `whiskerOptions`). Box plot whiskers use an enum-style
`whisker_type` (`tukey` / `min_max` / `percentile` with validated
`percentile_low < percentile_high`) that serializes to the exact strings the
frontend `boxplotOperator` parses, including its `"<low>/<high> percentiles"`
regex format — an LLM never has to guess the magic strings.
- **Config schemas are strict** (unknown fields rejected, SQL expressions
rejected on dimension-position columns, saved_metric rejected on the
histogram's binned column) with descriptive Pydantic errors, consistent with
the existing chart configs.
- `histogram_v2` added to the viz_type→chart_type alias map so clients that
send Superset's public viz name instead of the discriminator get translated
rather than rejected; `get_chart_type_schema` gains both types with examples;
`generate_chart` docstring and server instructions updated.
Part of a series extending MCP chart-type coverage (registry groundwork:
#39922).
### BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF
N/A (MCP service; no UI changes)
### TESTING INSTRUCTIONS
```bash
pytest tests/unit_tests/mcp_service/chart/test_histogram_boxplot_charts.py
# 24 new tests
pytest tests/unit_tests/mcp_service/chart/
# full chart suite
```
Manual: via an MCP client, `generate_chart` with
`{"dataset_id": <id>, "config": {"chart_type": "histogram", "column":
{"name": "<numeric_col>"}, "bins": 20}}`
returns a working preview; same for
`{"chart_type": "box_plot", "metrics": [{"name": "<col>", "aggregate":
"AVG"}], "distribute_across": [{"name": "<category_col>"}]}`.
### ADDITIONAL INFORMATION
- [ ] Has associated issue:
- [ ] Required feature flags:
- [ ] Changes UI
- [ ] Includes DB Migration (follow approval process in
[SIP-59](https://github.com/apache/superset/issues/13351))
- [ ] Migration is atomic, supports rollback & is backwards-compatible
- [ ] Confirm DB migration upgrade and downgrade tested
- [ ] Runtime estimates and downtime expectations provided
- [x] Introduces new feature or API
- [ ] Removes existing feature or API
🤖 Generated with [Claude Code](https://claude.com/claude-code)
https://claude.ai/code/session_014z1fQxTadTEvpCJLx9WnB8
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