diff --git a/src/test/java/com/mythlane/gravityflip/command/DefineValidationTest.java b/src/test/java/com/mythlane/gravityflip/command/DefineValidationTest.java
new file mode 100644
index 0000000..d39128b
--- /dev/null
+++ b/src/test/java/com/mythlane/gravityflip/command/DefineValidationTest.java
@@ -0,0 +1,93 @@
+package com.mythlane.gravityflip.command;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * Pure-data tests for {@link DefineValidation} — no Hytale runtime dependency.
+ *
+ * <p>Covers :
+ * <ul>
+ *   <li>Name regex accepts alnum + underscore + dash, 1..32 chars.</li>
+ *   <li>Name regex rejects blank, spaces, special chars, non-ASCII, over-length.</li>
+ *   <li>Componentwise min/max return smallest/largest per axis.</li>
+ *   <li>Inflate-max-by-1 convention (max block is INSIDE the AABB only if we add 1 per axis).</li>
+ * </ul>
+ */
+class DefineValidationTest {
+
+    // ---------- name regex ----------
+
+    @Test
+    void validName_acceptsAlnumUnderscoreDash() {
+        assertTrue(DefineValidation.isValidName("abc"));
+        assertTrue(DefineValidation.isValidName("my-zone_1"));
+        assertTrue(DefineValidation.isValidName("Z"));
+        assertTrue(DefineValidation.isValidName("a".repeat(32)));
+        assertTrue(DefineValidation.isValidName("ABC_123-xyz"));
+    }
+
+    @Test
+    void validName_rejectsNullEmptyBlankAndInvalidChars() {
+        assertFalse(DefineValidation.isValidName(null));
+        assertFalse(DefineValidation.isValidName(""));
+        assertFalse(DefineValidation.isValidName(" "));
+        assertFalse(DefineValidation.isValidName("my zone"));
+        assertFalse(DefineValidation.isValidName("a".repeat(33)));
+        assertFalse(DefineValidation.isValidName("name!"));
+        assertFalse(DefineValidation.isValidName("名前"));
+        assertFalse(DefineValidation.isValidName("../etc/passwd"));
+        assertFalse(DefineValidation.isValidName("has.dot"));
+    }
+
+    // ---------- componentwise min/max ----------
+
+    @Test
+    void componentwiseMin_returnsSmallestPerAxis() {
+        int[] a = {5, 10, -3};
+        int[] b = {1, 20, -7};
+        assertArrayEquals(new int[]{1, 10, -7}, DefineValidation.componentwiseMin(a, b));
+    }
+
+    @Test
+    void componentwiseMax_returnsLargestPerAxis() {
+        int[] a = {5, 10, -3};
+        int[] b = {1, 20, -7};
+        assertArrayEquals(new int[]{5, 20, -3}, DefineValidation.componentwiseMax(a, b));
+    }
+
+    @Test
+    void componentwise_orderIndependent() {
+        int[] a = {1, 2, 3};
+        int[] b = {4, 5, 6};
+        assertArrayEquals(
+                DefineValidation.componentwiseMin(a, b),
+                DefineValidation.componentwiseMin(b, a));
+        assertArrayEquals(
+                DefineValidation.componentwiseMax(a, b),
+                DefineValidation.componentwiseMax(b, a));
+    }
+
+    // ---------- inflate-max convention (block inclusion) ----------
+
+    /**
+     * A block occupies the cube between (x,y,z) and (x+1,y+1,z+1). If an AABB's max is the
+     * raw block coord (maxBlockX, maxBlockY, maxBlockZ), a player standing on top of that
+     * block is OUTSIDE the AABB. We therefore inflate max by +1 per axis.
+     */
+    @Test
+    void boxFromCorners_inflateMax_includesMaxBlock() {
+        int[] mn = {0, 64, 0};
+        int[] mx = {10, 70, 10};
+        // Player feet at (10.5, 70.5, 10.5) — standing in the maxBlock cube.
+        double px = 10.5, py = 70.5, pz = 10.5;
+        // Without inflate: max = (10,70,10) — player OUT.
+        assertFalse(px < mx[0] && py < mx[1] && pz < mx[2]);
+        // With inflate: max = (11,71,11) — player IN.
+        int[] mxInflated = {mx[0] + 1, mx[1] + 1, mx[2] + 1};
+        assertTrue(px < mxInflated[0] && py < mxInflated[1] && pz < mxInflated[2]);
+    }
+}