## ADDED Requirements

### Requirement: ObserverPosition types

The system SHALL export a discriminated union `ObserverPosition` with three variants: `surface` (planet + coord), `atmospheric` (planet + coord + altitude), and `space` (Vec3 + frame).

#### Scenario: Surface observer construction

- **WHEN** an `ObserverPosition` of type `surface` is constructed with a valid `PlanetConfig` and `SphericalCoord`
- **THEN** the object validates successfully
- **AND** the `PlanetConfig` is accessible inline without lookup

### Requirement: CoordinateFrame types and conversion

The system SHALL export `CoordinateFrame` as a union of `heliocentric`, `galactic`, and `custom`, plus pure conversion functions `convertFrame`, `toHeliocentric`, and `toGalactic`.

#### Scenario: Identity conversion

- **WHEN** `convertFrame(vec, heliocentric, heliocentric)` is called
- **THEN** the result equals the input vector

### Requirement: CelestialBody shape

The system SHALL export a `CelestialBody` interface with name, type, altitude, azimuth, apparent magnitude, angular diameter, distance in AU, and heliocentric position.

#### Scenario: Body validation

- **WHEN** a `CelestialBody` object is constructed with all required fields
- **THEN** Zod validation succeeds

### Requirement: CatalogStar and ObservedStar shapes

The system SHALL export `CatalogStar` (catalog-space, no observer fields) and `ObservedStar` (extends `CatalogStar` with altitude, azimuth, and extincted magnitude).

#### Scenario: Observed star construction

- **WHEN** an `ObservedStar` is created from a `CatalogStar` with added `altitude`, `azimuth`, and `extinctedMagnitude`
- **THEN** the object satisfies both the `CatalogStar` and `ObservedStar` contracts

### Requirement: SolarProvider interface

The system SHALL export a `SolarProvider` interface with `getBodies`, `getBody`, `getSunrise`, and `getSunset`, all accepting `ObserverPosition`, `Date`, and optional `AbortSignal`.

#### Scenario: SolarProvider cancellation

- **WHEN** `getBodies` is called with an `AbortSignal` that is aborted before resolution
- **THEN** the promise rejects with an abort error

### Requirement: StarProvider interface

The system SHALL export a `StarProvider` interface with `getVisibleStars` (returns `ObservedStar[]`), `queryCone` (returns `CatalogStar[]`), and `getStar`.

#### Scenario: StarProvider query

- **WHEN** `getVisibleStars` is called with a surface observer and `StarQueryOptions`
- **THEN** the returned array contains only `ObservedStar` entries with `altitude` and `azimuth` populated

### Requirement: TidalProvider interface

The system SHALL export a `TidalProvider` interface with `predictHeight` and `getExtremes`, accepting `PlanetConfig`, `SphericalCoord`, `Date`, and optional `AbortSignal`.

#### Scenario: Tidal prediction cancellation

- **WHEN** `predictHeight` is called with an aborted signal
- **THEN** the promise rejects with an abort error

### Requirement: WeatherState and WeatherProvider interface

The system SHALL export `WeatherState` and `WeatherProvider` with a locked interface for future `@suaveplan/weather` integration.

#### Scenario: WeatherProvider registration

- **WHEN** a `WeatherProvider` is registered with `UniverseClient`
- **THEN** `UniverseScene.weather` is populated after `getScene`

### Requirement: UniverseClient plugin registry

The system SHALL provide `UniverseClient` with typed `register` methods for `solar`, `stars`, `tides`, and `weather` domains, returning `this` for chaining.

#### Scenario: Register all providers

- **WHEN** providers are registered for all four domains
- **AND** `getScene` is called with valid observer and time
- **THEN** the returned `UniverseScene` contains `bodies`, `stars`, `tides`, and `weather`

### Requirement: UniverseScene shape

The system SHALL export `UniverseScene` with `bodies`, `stars`, optional `tides`, and optional `weather`.

#### Scenario: Scene without optional providers

- **WHEN** only `solar` and `stars` providers are registered
- **AND** `getScene` is called
- **THEN** the scene has `bodies` and `stars`, with `tides` and `weather` undefined

### Requirement: StarPacket BitSchema

The system SHALL export a `StarPacket` BitSchema quantising RA, Dec, magnitude, altitude, azimuth, and spectral class into ~11 bytes per star.

#### Scenario: Pack and unpack stars

- **WHEN** an array of `ObservedStar` objects is packed via `packStars`
- **AND** the buffer is unpacked via `unpackStars` with the correct count
- **THEN** the unpacked array has the same length
- **AND** each field is within the quantisation error tolerance of the original

### Requirement: CelestialBodyPacket BitSchema

The system SHALL export a `CelestialBodyPacket` BitSchema quantising altitude, azimuth, angular diameter, apparent magnitude, and body type.

#### Scenario: Pack and unpack bodies

- **WHEN** an array of `CelestialBody` objects is packed via `packBodies`
- **AND** the buffer is unpacked via `unpackBodies` with the correct count
- **THEN** the unpacked array has the same length and matching fields within tolerance