fix(appearance): preserve manual colorScheme override in production builds

Summary

Fix setColorScheme() not persisting after app reload (OTA update) on iOS when using darkMode: "class" in NativeWind.

Problem

When a React Native app using NativeWind 4.x with darkMode: "class" receives an OTA update and reloads, the manually set color scheme (e.g. "dark") is silently discarded and the app falls back to the system appearance.

Preconditions

• iOS device with light system theme
• App with user-selected dark theme stored in persistent storage (e.g. MMKV)
• OTA update triggers app JS bundle reload

Observed behavior

App reloads → displays light theme despite user preference being "dark".

Expected behavior

App reloads → displays dark theme as stored in user preferences.

Root Cause

appearance-observables.ts maintains two separate observables:

The colorScheme.get() method returns colorSchemeObservable.get() ?? systemColorScheme.get().

The bug: colorScheme.set(value) called Appearance.setColorScheme(value) (native side) but only updated colorSchemeObservable inside a NODE_ENV === "test" guard — meaning in production builds, colorSchemeObservable was never set and always remained undefined.

// Before (broken in production)
colorScheme.set(value) {
    appearance.setColorScheme(value); // native call
    if (process.env.NODE_ENV === "test") {
        colorSchemeObservable.set(...); // ← never runs in production
    }
}

The get() fallback then always resolved to systemColorScheme, which during OTA reload is briefly reset to the system value by the AppState "active" listener:

appStateListener = appState.addEventListener("change", (type) => {
  if (type === "active") {
    const colorScheme = appearance.getColorScheme() ?? "light"; // returns system "light"
    exports.systemColorScheme.set(colorScheme); // ← overwrites everything
  }
});

Result: colorSchemeObservable = undefined, systemColorScheme = "light" → app renders in light mode.

Why it worked on Android: Android does not fire an AppState "active" transition during OTA JS reload the same way iOS does, so systemColorScheme was not reset at the wrong moment.

Why timeouts didn't help: The issue is not a race condition — colorSchemeObservable was structurally never populated in production, regardless of timing.

Fix

Remove the NODE_ENV === "test" guard so colorSchemeObservable is always updated when colorScheme.set() is called. This makes the manual override survive any subsequent systemColorScheme changes triggered by Appearance or AppState events.

// After (correct)
colorScheme.set(value) {
    appearance.setColorScheme(value);
    // Always update so manual override is preserved regardless of environment
    colorSchemeObservable.set(value === "system" ? undefined : value);
}

Note: "system" maps to undefined (not "light") so that get() correctly falls through to the real-time systemColorScheme observable instead of being hardcoded.

Diff

- if (process.env.NODE_ENV === "test") {
-     colorSchemeObservable.set(value === "system" ? "light" : value);
- }
+ // Always update colorSchemeObservable so the manual override is preserved
+ // even when iOS resets the native appearance during OTA reload.
+ colorSchemeObservable.set(value === "system" ? undefined : value);

Testing

Affected versions

Reproduced on react-native-css-interop@0.2.3. Likely present in all prior versions with the same guard.