chore(docs): keep runtime tracing server-safe

Co-authored-by: Junior Garcia <jrgarciadev@gmail.com>

apps/docs/env.ts

@@ -1,25 +1,29 @@
-import {appendFileSync} from "node:fs";
-
 import {createEnv} from "@t3-oss/env-nextjs";
 import {z} from "zod";
 
 // #region agent log
-appendFileSync(
-  "/opt/cursor/logs/debug.log",
-  `${JSON.stringify({
-    data: {
-      featurebaseEndpointPresent: process.env["FEATUREBASE_API_ENDPOINT"] !== undefined,
-      featurebaseKeyPresent: process.env["FEATUREBASE_API_KEY"] !== undefined,
-      loopsEndpointPresent: process.env["LOOPS_API_ENDPOINT"] !== undefined,
-      loopsKeyPresent: process.env["LOOPS_API_KEY"] !== undefined,
-      nodeEnv: process.env["NODE_ENV"] ?? null,
-    },
-    hypothesisId: "D",
-    location: "apps/docs/env.ts:module-evaluation",
-    message: "Validating documentation runtime environment",
-    timestamp: Date.now(),
-  })}\n`,
-);
+if (typeof window === "undefined") {
+  const fileSystem = process.getBuiltinModule("fs") as {
+    appendFileSync(path: string, data: string): void;
+  };
+
+  fileSystem.appendFileSync(
+    "/opt/cursor/logs/debug.log",
+    `${JSON.stringify({
+      data: {
+        featurebaseEndpointPresent: process.env["FEATUREBASE_API_ENDPOINT"] !== undefined,
+        featurebaseKeyPresent: process.env["FEATUREBASE_API_KEY"] !== undefined,
+        loopsEndpointPresent: process.env["LOOPS_API_ENDPOINT"] !== undefined,
+        loopsKeyPresent: process.env["LOOPS_API_KEY"] !== undefined,
+        nodeEnv: process.env["NODE_ENV"] ?? null,
+      },
+      hypothesisId: "D",
+      location: "apps/docs/env.ts:module-evaluation",
+      message: "Validating documentation runtime environment",
+      timestamp: Date.now(),
+    })}\n`,
+  );
+}
 // #endregion
 
 export const env = createEnv({