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name: extension-development description: "Build and debug sktime-compatible estimators, extension templates, tags, soft dependencies, and focused estimator checks." disable-model-invocation: true metadata: disco-role: operating license: BSD 3-Clause

Extension Development

Use this sub-skill when implementing, debugging, or maintaining an sktime-compatible estimator or extension package.

Route here

• Choose an extension template for a forecaster, transformer, classifier, regressor, clusterer, detector, aligner, splitter, metric, or parameter fitter.
• Implement private hooks such as _fit, _predict, _transform, or _split.
• Set tags for mtypes, capabilities, soft dependencies, maintainers, and tests.
• Debug check_estimator, get_test_params, or focused pytest failures.
• Isolate soft dependencies and decide when tests:vm is required.

Route away

User-level forecasting, panel learning, data conversion, or evaluation workflows belong to their respective sub-skills. Release automation and CI-specific host setup are outside this operating skill unless explicitly requested.

References and helper

• Extension templates for scitype-to-template mapping and private method contracts.
• Testing and maintenance for check_estimator, test scenarios, soft dependency policy, and focused checks.
• Troubleshooting for common estimator failures.
• Use scripts/scaffold_estimator.py to list template mappings or generate a tiny stub, and scripts/check_estimator_smoke.py for focused conformance diagnostics.