# Method Summary

The SPARC-facing phase detector uses directly observable rotation-curve quantities.

## 1. Baryonic velocity proxy

The pipeline constructs a baryonic velocity contribution from the SPARC gas, disk, and bulge components.

## 2. Acceleration ratio

Because both observed and baryonic accelerations are of the form `V^2 / r`, the radial coordinate cancels in their ratio:

```text
Phi(r) = g_obs(r) / g_bar(r) = V_obs(r)^2 / V_bar(r)^2
```

## 3. Log phase-amplification field

```text
y(r) = ln Phi(r)
```

## 4. Radial phase drift

```text
B_y = y_outer - y_inner
```

This is the main radial phase-state statistic used in the quickstart test.

## 5. Baryonic structural proxy

The package computes a structural stress proxy from galaxy-level baryonic observables. The central test is whether this proxy predicts or correlates with radial phase drift.

## 6. No-knob rule

The law layer is not retuned per galaxy. The detector measures phase-state behaviour; it does not change the frozen law after inspecting each galaxy.
