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ASTROCARTOGRAPHY_BACKEND_STANDARD

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TheDaniel166 edited this page Oct 15, 2026 · 3 revisions

Astrocartography Backend Standard

Version: 0.1 Date: 2026-06-11 Status: Active backend admission packet for Phase 10 REST evaluation Scope: moira.astrocartography

This standard records the backend truth that may be exposed by the REST server for P10-01 Astrocartography. It is not a map-rendering standard and does not admit dense grid, contour, or tiled map products.

It is downstream of:

  • wiki/00_foundations/ENGINE_VS_SERVICE_BOUNDARY.md
  • docs/architecture/MOIRA_SERVER_ROUTE_ADMISSION_CHECKLIST.md
  • docs/architecture/MOIRA_SERVER_PHASE10_LEDGER.md
  • wiki/03_validation/VALIDATION_EXPERIMENTAL.md

1. Governing Object

The governing object is the AstroCartoGraphy geographic line family for one chart epoch:

  • MC meridian
  • IC meridian
  • Ascendant sampled curve
  • Descendant sampled curve
  • subplanetary zenith point
  • subplanetary nadir point

These are geographic products on Earth. They are not chart aspects, house cusps, map projections, or rendered graphics.

2. Public Engine Surface

Authoritative module:

  • moira/astrocartography.py

Public vessels:

  • ACGLine
  • SubPlanetaryPoint

Public functions:

  • acg_lines(planet_ra_dec, gmst_deg, lat_step=2.0, jd_ut=None, refraction=False)
  • acg_from_chart(chart, bodies=None, lat_step=2.0, refraction=False)
  • subplanetary_points(planet_ra_dec, gmst_deg)
  • subplanetary_from_chart(chart, bodies=None)

Facade exposure:

  • SpatialFacadeMixin.astrocartography(...)
  • SpatialFacadeMixin.subplanetary_points(...)

3. Frame And Input Truth

Direct low-level inputs:

  • body name
  • apparent geocentric right ascension in degrees
  • apparent geocentric declination in degrees
  • Greenwich apparent sidereal time in degrees
  • optional Julian Day for lunar topocentric handling
  • optional latitude sampling step
  • optional refraction flag

Chart-backed inputs:

  • ChartContext
  • optional selected bodies
  • optional latitude sampling step
  • optional refraction flag

Frame doctrine:

  • RA/Dec are apparent geocentric equatorial coordinates of date unless the caller explicitly owns another direct-input source.
  • gmst_deg is Greenwich apparent sidereal time in degrees.
  • MC/IC line longitudes are geographic longitudes.
  • ASC/DSC points are sampled (latitude, longitude) geographic pairs.
  • Subplanetary point latitude is WGS-84 geodetic latitude derived from the geocentric declination.
  • Subplanetary point longitude is wrapped to [-180, 180).

4. Result Semantics

ACGLine preserves:

  • planet
  • line_type
  • longitude
  • points

Line-type invariants:

  • MC and IC lines use longitude and have no sampled points.
  • ASC and DSC lines use sampled points and have no single longitude.
  • One body yields four ACG lines.

SubPlanetaryPoint preserves:

  • planet
  • point_type
  • latitude
  • longitude

Point-type invariants:

  • one body yields one Zenith point and one Nadir point
  • nadir latitude is the negative of zenith latitude
  • nadir longitude is antipodal to zenith longitude

5. Bounded Output Policy

First REST admission may expose:

  • bounded ACG line products
  • bounded subplanetary point products

First REST admission must not expose:

  • dense map grids
  • rendered maps
  • tiled map products
  • contour extraction
  • unbounded body catalogs
  • fixed-star all-catalog ACG sweeps

Sampling policy:

  • lat_step must be finite and in (0, 178].
  • REST transport should use a stricter operational default and maximum body count before admission.
  • ASC/DSC sampling is a line approximation, not a rendered cartographic path.

6. Validation And Evidence

Existing validation:

  • tests/unit/test_astrocartography.py
  • tests/unit/test_session_fixes.py
  • wiki/03_validation/VALIDATION_EXPERIMENTAL.md

Covered invariants include:

  • four line vessels per body
  • MC/IC antipodal meridian behavior
  • zero-declination ASC/DSC meridian behavior
  • high-declination circumpolar latitude skipping
  • ASC/DSC symmetry around the MC meridian
  • WGS-84 geodetic latitude conversion for subplanetary points
  • chart wrapper delegation to apparent sidereal time and sky-position truth
  • small-body subplanetary points through the admitted planet_at surface
  • rejection of invalid sampling and non-finite coordinate inputs

7. REST Admission Position

P10-01 Astrocartography is eligible to move from evaluation to transport design for bounded line and subplanetary products.

REST design must still decide:

  • direct RA/Dec route shape
  • chart-backed route shape
  • maximum body count
  • REST lat_step bounds
  • response provenance fields
  • whether small bodies are admitted in first transport or constrained to chart-contained bodies only

Do not admit dense grid or map-rendering routes as part of first P10-01 transport.

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