# GRAV-BRIDGE-I v0.1.0 Guide

## Purpose

GRAV-BRIDGE-I is the third instrument in the chain:

`STRUC-I + STRUC-PERC-I -> GRAV-BRIDGE-I`

It does not reproduce either structural chamber. It ingests their frozen galaxy-level outputs
and tests whether they improve prediction of the SPARC gravitational discrepancy on galaxies
excluded from fitting.

## Registered models

- **M0:** nonlinear spline of local `log10_g_bar`.
- **M1:** M0 plus nonlinear normalized radius.
- **M2:** M1 plus ordinary whole-profile controls.
- **M_I:** M2 plus STRUC-I features.
- **M_P:** M2 plus STRUC-PERC-I features.
- **M_IP:** M2 plus both chamber feature families.

Using M2 as the common structural base prevents chamber features from receiving credit for
ordinary ladder length, range, IQR, median gap, or gap variance.

## Validation

Five folds are formed by galaxy. Every radial point belonging to a galaxy remains in one fold.
Fit weights make each galaxy contribute equal total weight despite different numbers of radii.
The primary score is galaxy-balanced RMSE.

## Nulls

1. **Cross-galaxy signature permutation:** moves all chamber signatures together between galaxies.
2. **Galaxy target-curve permutation:** moves complete discrepancy curves between galaxies and
   linearly samples the source curve at the recipient's normalized radii.

## Starting the chamber

Windows: double-click `RUN_GRAV_BRIDGE_I.bat`.

Command line registered run: double-click `RUN_REGISTERED_ANALYSIS.bat`.

Linux/macOS: `./RUN_GRAV_BRIDGE_I.sh`.


## Windows environment location

The launcher uses `%LOCALAPPDATA%\\UNNS\\GBI010` rather than a nested local `.venv`. See `WINDOWS_ERROR_206_REPAIR.md`.

---

## v0.3 project interpretation

This document belongs to the external transfer experiment. Numerical, technical, protocol, or provenance content above is preserved. The transfer result tests one static global architecture: it does not negate the galaxy-specific structural information carried by the curves. Complete curves retain identity, and ρ is the leading channel for local or regime-conditioned follow-up.

