Required inputs
Requested observable
Celestial body
Observer contract when local
Shared instant and ephemeris
Ordered execution
Work the protocol
- 1
Classify the output as Earth-center or observer-relative.
- 2
Require an observer for topocentric work.
- 3
Hold instant and ephemeris constant across comparisons.
- 4
Calculate both origins only when the protocol asks for a comparison.
- 5
Label each output at the field level.
Outputs
- Origin decision
- Eligible input set
- Parallel positions when requested
Done only when
- Every position names its origin.
- Shared inputs are frozen.
- No interpretation chooses the geometry.
Fail closed
Refusal conditions
- Topocentric output lacks an observer.
- Origin changes after seeing a sign label.
- Two origins are averaged.