Jyotisha/docs/research/ephemeris_candidate_adapter_spike_2026_06_23.md

Ephemeris Candidate Adapter Spike - 2026-06-23

Purpose: decide whether a non-default candidate_backend is ready to enter the EphemerisAdapterContract parity gate.

Run:

python3 scripts/ephemeris_candidate_adapter_spike.py

swisseph_wasm_candidate

swisseph_wasm_candidate has local browser assets and package dependencies, so it is a plausible offline/PWA candidate. It is not a separate accuracy authority and it is not ready for runtime_setting_exposure.

The license_gate is the important blocker: Swiss Ephemeris WASM still follows Swiss Ephemeris licensing boundaries, so distribution claims must be reviewed before this becomes a user-selectable backend.

The local package metadata currently reports:

Package	package_license
@swisseph/browser	AGPL-3.0
swisseph-wasm	GPL-3.0-or-later

That means the WASM path is useful for local/PWA fallback experiments, but it must not be treated as a low-risk proprietary desktop dependency without a license decision.

xalen_ephemeris_candidate

xalen_ephemeris_candidate remains the best permissive-direction spike because vedika-io/xalen-ephemeris is tracked as Apache-2.0. There is no local executable mirror in this workspace yet, so the current spike status is documentation-only.

vedastro_service_adapter_candidate

vedastro_service_adapter_candidate is now recognized as a formal candidate backend shape, but only through a reviewed external service boundary.

It is still blocked for direct runtime_setting_exposure because the workspace does not yet contain:

1. a real adapter executor,
2. timeout / retry policy,
3. normalized parity rows that satisfy EphemerisAdapterContract,
4. response provenance fields that make external-service usage auditable.

This keeps VedAstro in the engineering path without pretending that its C# stack is a drop-in local Python replacement.

Gate

All candidates are blocked until parity_gate_required is satisfied:

1. Produce rows matching EphemerisAdapterContract.
2. Compare against swisseph_python baseline rows.
3. Pass longitude_delta_arcsec thresholds for Sun, Moon, Ascendant, Rahu, and Ketu.
4. Preserve ayanamsa_value, retrograde, backend metadata, node policy, and house policy.
5. Keep runtime_setting_exposure blocked until the above is verified.

Decision: do not expose any non-SwissEph runtime setting yet. The next implementation step is an isolated executable adapter only after local assets and license review are complete.