diff --git a/src/main/java/com/mythlane/gravityflip/wand/spike/WandAssetSpike.java b/src/main/java/com/mythlane/gravityflip/wand/spike/WandAssetSpike.java
new file mode 100644
index 0000000..7720566
--- /dev/null
+++ b/src/main/java/com/mythlane/gravityflip/wand/spike/WandAssetSpike.java
@@ -0,0 +1,71 @@
+package com.mythlane.gravityflip.wand.spike;
+
+/**
+ * <h2>04-00 Spike artifact — NOT WIRED INTO THE PLUGIN.</h2>
+ *
+ * <p>This class is intentionally <strong>not referenced</strong> from
+ * {@code GravityFlipPlugin}. It exists purely as an executable-looking
+ * documentation of the empirical investigation that produced
+ * {@code .planning/phases/04-wand-commands/04-00-SPIKE-RESULT.md}.
+ *
+ * <p><b>Locked decision (see SPIKE-RESULT.md):</b> we will <em>not</em> register
+ * a brand-new {@code Item} asset store from a plugin — no decompiled builtin
+ * plugin does that, and it risks duplicating the core's Item store. Instead,
+ * Plan 04-01 will:
+ *
+ * <ol>
+ *   <li>Subclass {@link com.hypixel.hytale.server.core.modules.interaction.interaction.config.SimpleInstantInteraction}
+ *       as {@code GravityFlipWandInteraction} with its own {@code BuilderCodec}.</li>
+ *   <li>In {@code GravityFlipPlugin.setup()}, call:
+ *       <pre>{@code
+ *       getCodecRegistry(Interaction.CODEC)
+ *           .register("GravityFlipWand",
+ *                     GravityFlipWandInteraction.class,
+ *                     GravityFlipWandInteraction.CODEC);
+ *       }</pre>
+ *       This is the pattern used by PortalsPlugin:74, CreativeHubPlugin:149,
+ *       InstancesPlugin:158, CraftingPlugin:130, TeleporterPlugin:73,
+ *       ObjectivePlugin:210-211 — 8+ builtin precedents.</li>
+ *   <li>Plan 04-02 will identify the concrete vanilla itemID to hand out in
+ *       {@code /gravityflip wand} by iterating
+ *       {@code Item.getAssetStore().getAssetMap()} at runtime (disposable
+ *       probe), then hardcode the chosen itemID (likely a hatchet/axe variant
+ *       that already exposes Primary + Secondary interactions).</li>
+ * </ol>
+ *
+ * <p>The code below is illustrative only. It compiles against stubs in
+ * javadoc and is <strong>not invoked</strong>. Delete this class at the start
+ * of Plan 04-01.
+ *
+ * <h3>Why VANILLA_COPY and not a brand-new Item JSON?</h3>
+ *
+ * <p>Hypothesised pattern (rejected):
+ * <pre>{@code
+ * // UNPROVEN: no builtin plugin does this for Item.class.
+ * getAssetRegistry().register(
+ *     HytaleAssetStore.builder(Item.class, Item.ASSET_MAP)
+ *                     .setPath("Items")
+ *                     .build());
+ * }</pre>
+ *
+ * <p>User-confirmed pattern (adopted):
+ * <blockquote>
+ *   « On peut copier un item vanilla genre la hache et changer des propriétés
+ *   genre couleur etc. » — 2026-04-23
+ * </blockquote>
+ *
+ * <p>Copy an existing vanilla item (hatchet / pickaxe / sword — anything
+ * exposing {@code Primary} + {@code Secondary}) and hijack the click
+ * behaviour via the {@code Interaction.CODEC} registry. Visual polish
+ * (custom colour / display name) can be layered later without blocking v1.
+ */
+public final class WandAssetSpike {
+
+    /** Not callable. Not invoked. Documentation-only. */
+    private WandAssetSpike() {
+        throw new UnsupportedOperationException(
+                "WandAssetSpike is a 04-00 documentation artifact. "
+                + "See .planning/phases/04-wand-commands/04-00-SPIKE-RESULT.md. "
+                + "Delete this class at the start of Plan 04-01.");
+    }
+}