# Licensing gate

Status: **GO for an MIT package**, subject to the repository operator having
authority to publish the Zodiacs.org-authored TypeScript under the package's
MIT license.

## Provenance chain

The package implementation was adapted from these Zodiacs.org TypeScript
modules:

- `src/lib/engine/full.ts` — planetary positions and chart assembly
- `src/lib/engine/houses.ts` — independently implemented spherical
  trigonometry for angles, whole-sign houses, and Placidus houses
- `src/lib/engine/aspects.ts` — aspect matching
- `src/lib/engine/synastry.ts` — inter-chart aspect and balance summaries
- `src/lib/engine/returns.ts` — longitude crossing and Saturn-return scans
- `src/lib/time/localToUtc.ts` — host-`Intl` timezone conversion
- `src/lib/geo/search.ts` — client for the separately hosted GeoNames index

The computational dependency is `astronomy-engine@2.1.19`. Its installed npm
metadata declares MIT, names Donald Cross as author, and links to
`https://github.com/cosinekitty/astronomy`. Its distributed
`esm/astronomy.js` begins with a preserved MIT notice and a 2019–2023 Don Cross
copyright line. The package uses its geocentric vectors, coordinate rotations,
Moon state, sidereal time, and date helpers.

Repository and dependency searches found no Swiss Ephemeris runtime import,
package dependency, vendored source, or generated lookup table in this npm
package.

## Swiss Ephemeris exclusion

The website test suite contains Placidus reference constants generated with
`pyswisseph`. Those constants and their surrounding test block were
deliberately **not copied**. Package accuracy tests contain only:

- public JPL Horizons longitude vectors;
- geometric and astronomical invariants;
- synthetic aspect fixtures; and
- behavior computed directly by this package.

The Placidus implementation is the site's own formula-based TypeScript, not a
port or translation of Swiss Ephemeris code. This licensing decision must be
revisited before accepting any Swiss Ephemeris source, binary, table, or
generated fixture into the package.

## GeoNames and timezone data

The `./geo` entry point is code-only and bundles no place records. Compatible
indexes may be derived from GeoNames `cities15000`, `admin1CodesASCII`, and
`countryInfo`, which are CC BY 4.0. Downstream users who host or redistribute
that data are instructed to retain `NOTICE`.

Timezone conversion uses the host's `Intl`/ICU implementation. The package
does not redistribute tzdb, so historical timezone completeness is a runtime
property rather than a package-data guarantee.