diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index bb90b91..c5b77a8 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -32,10 +32,13 @@ jobs:
         uses: gradle/actions/setup-gradle@v4
 
       - name: Run JVM tests
-        run: ./gradlew :phosphor-core:jvmTest :phosphor-lumos:jvmTest
+        run: ./gradlew jvmTest
 
-      - name: Check formatting
-        run: ./gradlew :phosphor-core:ktlintCheck :phosphor-lumos:ktlintCheck
+      - name: Verify formatting
+        run: ./gradlew ktlintFormat --no-rebuild
+
+      - name: Check formatting diff
+        run: git diff --exit-code
 
   ios_compile:
     name: iOS Compile
@@ -59,7 +62,7 @@ jobs:
 
   test:
     name: Tests
-    runs-on: ubuntu-latest
+    runs-on: macos-latest
     needs: [jvm, ios_compile]
     if: ${{ always() }}
 
@@ -70,3 +73,21 @@ jobs:
             echo "Required CI jobs did not all pass."
             exit 1
           fi
+
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up JDK 21
+        uses: actions/setup-java@v4
+        with:
+          java-version: '21'
+          distribution: 'zulu'
+
+      - name: Setup Gradle
+        uses: gradle/actions/setup-gradle@v4
+
+      - name: Run build
+        run: ./gradlew build
+
+      - name: Run all tests
+        run: ./gradlew allTests
diff --git a/phosphor-core/src/commonMain/kotlin/link/socket/phosphor/field/VoxelSphere.kt b/phosphor-core/src/commonMain/kotlin/link/socket/phosphor/field/VoxelSphere.kt
index 40dcac4..68573d7 100644
--- a/phosphor-core/src/commonMain/kotlin/link/socket/phosphor/field/VoxelSphere.kt
+++ b/phosphor-core/src/commonMain/kotlin/link/socket/phosphor/field/VoxelSphere.kt
@@ -159,8 +159,11 @@ class VoxelSphere(val resolution: Int) {
 
 /**
  * Return true when this voxel's outward direction faces a viewer on the +Z axis.
+ *
+ * [orbRotation] is an Euler-style XYZ rotation in radians, matching [Vector3.rotatedBy].
+ * It is not a quaternion despite earlier naming.
  */
 fun Voxel.facingCamera(
-    orbQuaternion: Vector3,
+    orbRotation: Vector3,
     threshold: Float = 0.15f,
-): Boolean = unitDirection.rotatedBy(orbQuaternion).z > threshold
+): Boolean = unitDirection.rotatedBy(orbRotation).z > threshold
diff --git a/phosphor-core/src/commonTest/kotlin/link/socket/phosphor/renderer/SimulationFrameTest.kt b/phosphor-core/src/commonTest/kotlin/link/socket/phosphor/renderer/SimulationFrameTest.kt
index 3938243..b5f9ca8 100644
--- a/phosphor-core/src/commonTest/kotlin/link/socket/phosphor/renderer/SimulationFrameTest.kt
+++ b/phosphor-core/src/commonTest/kotlin/link/socket/phosphor/renderer/SimulationFrameTest.kt
@@ -7,6 +7,7 @@ import kotlin.test.assertNotNull
 import kotlinx.serialization.json.Json
 import link.socket.phosphor.render.AsciiCell
 import link.socket.phosphor.render.CellBuffer
+import link.socket.phosphor.test.assertFloatEquals
 
 class SimulationFrameTest {
     @Test
@@ -51,10 +52,10 @@ class SimulationFrameTest {
                 normalY = floatArrayOf(1f, 1f),
             )
 
-        assertEquals(0.2f, frame.cellAt(0, 0).luminance)
-        assertEquals(0.8f, frame.cellAt(1, 0).luminance)
-        assertEquals(-0.5f, frame.cellAt(0, 0).normalX)
-        assertEquals(1f, frame.cellAt(1, 0).normalY)
+        assertFloatEquals(0.2f, frame.cellAt(0, 0).luminance)
+        assertFloatEquals(0.8f, frame.cellAt(1, 0).luminance)
+        assertFloatEquals(-0.5f, frame.cellAt(0, 0).normalX)
+        assertFloatEquals(1f, frame.cellAt(1, 0).normalY)
     }
 
     @Test
diff --git a/phosphor-core/src/commonTest/kotlin/link/socket/phosphor/test/FloatAssertions.kt b/phosphor-core/src/commonTest/kotlin/link/socket/phosphor/test/FloatAssertions.kt
new file mode 100644
index 0000000..0d797ad
--- /dev/null
+++ b/phosphor-core/src/commonTest/kotlin/link/socket/phosphor/test/FloatAssertions.kt
@@ -0,0 +1,12 @@
+package link.socket.phosphor.test
+
+import kotlin.test.assertEquals
+import kotlin.test.assertNotNull
+
+internal fun assertFloatEquals(
+    expected: Float,
+    actual: Float?,
+    tolerance: Float = 1e-4f,
+) {
+    assertEquals(expected, assertNotNull(actual), absoluteTolerance = tolerance)
+}
diff --git a/phosphor-lumos/src/commonTest/kotlin/link/socket/phosphor/lumos/VoxelFrameBuilderTest.kt b/phosphor-lumos/src/commonTest/kotlin/link/socket/phosphor/lumos/VoxelFrameBuilderTest.kt
index cdc255d..0a6b390 100644
--- a/phosphor-lumos/src/commonTest/kotlin/link/socket/phosphor/lumos/VoxelFrameBuilderTest.kt
+++ b/phosphor-lumos/src/commonTest/kotlin/link/socket/phosphor/lumos/VoxelFrameBuilderTest.kt
@@ -203,10 +203,10 @@ class VoxelFrameBuilderTest {
 
         repeat(200) { builder.build(snapshot(atmosphere = fast), dt = 0.5f) }
 
-        assertTrue(builder.pulsePhase in 0f..twoPi)
-        assertTrue(builder.patternPhase in 0f..patternWrap)
-        assertTrue(builder.orbRotationX in 0f..twoPi)
-        assertTrue(builder.orbRotationY in 0f..twoPi)
+        assertWrappedPhase("pulsePhase", builder.pulsePhase, twoPi)
+        assertWrappedPhase("patternPhase", builder.patternPhase, patternWrap)
+        assertWrappedPhase("orbRotationX", builder.orbRotationX, twoPi)
+        assertWrappedPhase("orbRotationY", builder.orbRotationY, twoPi)
     }
 
     @Test
@@ -395,4 +395,16 @@ class VoxelFrameBuilderTest {
             atmosphere = atmosphere,
             atmosphereTransition = transition,
         )
+
+    private fun assertWrappedPhase(
+        name: String,
+        actual: Float,
+        upperBound: Float,
+    ) {
+        val tolerance = 1e-4f
+        assertTrue(
+            actual >= -tolerance && actual <= upperBound + tolerance,
+            "$name should stay in [0, $upperBound], got $actual",
+        )
+    }
 }