[#479] Add Builder Code (ERC-8021) attribution

lib/builder-code.ts

@@ -0,0 +1,20 @@
+/**
+ * Base Builder Code (ERC-8021) attribution for PlotLink transactions.
+ *
+ * Appends a Builder Code suffix to transaction calldata so Base indexers
+ * can attribute onchain activity back to PlotLink.
+ *
+ * Register at base.dev and set NEXT_PUBLIC_BUILDER_CODE in env vars.
+ */
+
+import { Attribution } from "ox/erc8021";
+
+const BUILDER_CODE = process.env.NEXT_PUBLIC_BUILDER_CODE ?? "";
+
+/**
+ * Pre-computed ERC-8021 data suffix for the configured Builder Code.
+ * Returns undefined if Builder Code is not configured (attribution disabled).
+ */
+export const DATA_SUFFIX: `0x${string}` | undefined = BUILDER_CODE
+  ? Attribution.toDataSuffix({ codes: [BUILDER_CODE] })
+  : undefined;

lib/wagmi.ts

@@ -3,6 +3,7 @@ import { base, baseSepolia } from "wagmi/chains";
 import { injected } from "wagmi/connectors";
 import { farcasterMiniApp } from "@farcaster/miniapp-wagmi-connector";
 import { createFallbackTransport } from "./rpc";
+import { DATA_SUFFIX } from "./builder-code";
 
 const IS_MAINNET = process.env.NEXT_PUBLIC_CHAIN_ID === "8453";
 
@@ -14,6 +15,7 @@ export const config = createConfig({
     [baseSepolia.id]: IS_MAINNET ? http() : createFallbackTransport(),
   },
   ssr: true,
+  ...(DATA_SUFFIX ? { dataSuffix: DATA_SUFFIX } : {}),
 });
 
 declare module "wagmi" {

package.json

@@ -21,6 +21,7 @@
     "@supabase/supabase-js": "^2.99.1",
     "@tanstack/react-query": "^5.90.21",
     "next": "16.1.6",
+    "ox": "^0.14.8",
     "react": "19.2.3",
     "react-dom": "19.2.3",
     "viem": "^2.47.2",