# Continued Cassini–Mercury study

Started 5 September 2026, 19:51 UTC, after the user requested an overnight
attempt to repair the joint model. This is a new exploratory study. Earlier
results and failed candidates remain frozen.

The target is one explicitly specified effective action with (a) a sensible
constraint and propagation structure on the backgrounds tested, (b) the
Cassini quadrupole and light-propagation constraints, and (c) Mercury's
relativistic motion. Agreement with published marginal summaries is distinct
from fitting raw tracking observations. MESSENGER's published beta estimate
already uses a Cassini gamma prior; no independent joint likelihood is implied.

Work streams, to be pursued sequentially or with independent numerical jobs:

1. Audit the failed scalar principal action. Check alternatives to a generic
   propagating khronon, especially the separately defined kinetic-conformal
   constraint system. A singular parameter limit is not a derivation of a new
   degree-of-freedom count.
2. Test whether a stable response modification can preserve the galaxy proxy
   and both solar tests in the original propagating metric family. Keep tail,
   quadrupole and stability failures, including analytic obstructions.
3. For any surviving effective candidate, derive its stationary equations and
   scalar constraints from the same action. Check the full range of response
   coefficients and directions, and a spatially varying 3D constraint operator.
4. Derive or verify the appropriate PPN coefficients, including preferred-frame
   terms; integrate the relevant Mercury perturbations and light delays.
   Separate an isolated high-acceleration calculation from unsolved global
   relativistic matching to the Galactic field.
5. Strengthen the external-field and numerical controls if the original static
   response is retained. Changing the kinetic action alone does not require
   pretending that already verified static results are new predictions.
6. Inspect obvious consistency costs, including homogeneous cosmology and
   special-background degeneracy. A successful local solar candidate must not
   be advertised as a complete cosmological or quantum theory.
7. Publish only reproducible calculations, clear assumptions and their actual
   limitations. Attribute imported gravity frameworks. Preserve the earlier
   failed extension as part of the research record.

Numerical conventions and primary observational sources are inherited from
[CASSINI_MERCURY_PROTOCOL.md](CASSINI_MERCURY_PROTOCOL.md). New theory sources
will be recorded alongside their use. The overnight time allowance is not a
guarantee that a physically satisfactory repair exists.
