fix(sandbox): keep preview cache project-relative

Author: iamjr15

apps/agent-worker/src/durable-objects/agent-run-app-builder.ts

@@ -587,6 +587,7 @@ async function startAppBuilderDevServer(
       cwd: workspace.dir,
       env: {
         CHEATCODE_APP_RUNTIME: "next",
+        CHEATCODE_NEXT_DIST_DIR: "../cache/next",
         CHOKIDAR_USEPOLLING: "true",
         WATCHPACK_POLLING: "1000",
       },

apps/agent-worker/src/durable-objects/project-sandbox-package-runtime.ts

@@ -54,11 +54,13 @@ export function projectPackageEnvironment(
   if (!workspaceSlug) return requested;
   const modulesDir = projectLocalModulesDir(workspaceSlug);
   const requestedNodePath = requested?.["NODE_PATH"];
+  const requestedNextDistDir = requested?.["CHEATCODE_NEXT_DIST_DIR"];
   const preferredRuntime = requested?.["CHEATCODE_APP_RUNTIME"] === "expo" ? "expo" : "next";
   const fallbackRuntime = preferredRuntime === "expo" ? "next" : "expo";
   return {
     ...requested,
-    CHEATCODE_NEXT_DIST_DIR: `${projectLocalCacheDir(workspaceSlug)}/next`,
+    CHEATCODE_NEXT_DIST_DIR:
+      requestedNextDistDir ?? `../../home/node/.cheatcode/projects/${workspaceSlug}/cache/next`,
     NODE_PATH: [
       modulesDir,
       `${APP_RUNTIME_ROOT}/${preferredRuntime}/node_modules`,