compatibility-synastry

Compatibility & Synastry

Use this skill whenever someone asks how two people work together — romantically, in friendship, or in partnership. Three complementary tools:

Tool	Question it answers
Synastry	"How do our energies interact?" (each person's planets aspecting the other's)
Composite	"What is the relationship itself like?" (a third chart for the bond)
Davison / Midpoint	"What's the time-space midpoint of our two charts?" (an alternative composite based on real averaged ephemeris time + location)

Required Information

Two complete subjects — for EACH person:

1. Full birth date
2. Birth time (precision matters; flag if missing)
3. Birth location

Standard Procedure for Birth-Data Endpoints

Any endpoint that takes a birth chart (natal, synastry, composite, transits, returns, progressions, Human Design, Vedic, ACG) MUST follow this sequence. Skipping any step produces a wrong chart — usually wrong by hours of arc.

Step 1 — Resolve location to coordinates

If you don't already have precise lat/lon, call:

GET /location/autocomplete?query=<city, country>&limit=5

Confirm the right hit with the user if there's ambiguity (e.g. "Portland, OR" vs "Portland, ME"). Record the latitude and longitude of the chosen result.

Step 2 — Resolve timezone for that location AT THE BIRTH DATE

Historical timezone rules matter. A city's UTC offset in 1962 may differ from today (DST rules, war time, jurisdiction changes). Always look up the timezone for the specific birth date.

POST /timezone/lookup
{ "latitude": <lat>, "longitude": <lon> }

Response gives an IANA timezone string like "America/Los_Angeles". The BirthLocation field below REQUIRES this — it is not optional.

Step 3 — Build the request body

The SubjectRequest schema requires birth_datetime, birth_location, and name. The IANA timezone goes into birth_location.timezone:

{
  "subject": {
    "name": "Subject",
    "birth_datetime": { "iso": "1990-04-15T14:30:00" },
    "birth_location": {
      "latitude": 41.8781,
      "longitude": -87.6298,
      "timezone": "America/Chicago",
      "city": "Chicago",
      "country": "United States"
    }
  }
}