Source and license notes

Reviewed 2026-08-30. Behavioral reference: pinned upstream package. The upstream xlsx package has separate proprietary terms. It is a behavior/quality reference only; no upstream instructions, scripts or assets were copied.

Copied: nothing. Rewritten: all instructions, code, fixtures and classroom material. Prompthon adaptations: a distinct Structure boundary, tenant-scoped persistence, synthetic data, approval/readback safeguards, portable setup, English/Chinese exercises and reset behavior. The underlying openpyxl library is a declared dependency, not copied skill code.

See the shared source audit. Package-specific license conditions take precedence over an upstream repository's general license; in particular, xlsx material is not vendored.