diff --git a/site/decodal-site/src/scripts/playground-examples.js b/site/decodal-site/src/scripts/playground-examples.js
index 40d3c3b..5aabc7d 100644
--- a/site/decodal-site/src/scripts/playground-examples.js
+++ b/site/decodal-site/src/scripts/playground-examples.js
@@ -3,6 +3,7 @@ export const playgroundExamples = [
     id: 'product-api-production',
     title: 'Production API deployment',
     activePath: 'main.dcdl',
+    entryPath: 'main.dcdl',
     files: {
       'main.dcdl': `let
     schema = import "./schemas/service.dcdl";
@@ -105,6 +106,7 @@ image = "registry.example.com/checkout-api:2026.06.15";
     id: 'tenant-enterprise-plan',
     title: 'Enterprise tenant contract',
     activePath: 'main.dcdl',
+    entryPath: 'main.dcdl',
     files: {
       'main.dcdl': `let
     schema = import "./schemas/tenant.dcdl";
@@ -192,6 +194,7 @@ Acme = {
     id: 'event-pipeline-prod',
     title: 'Event ingestion pipeline',
     activePath: 'main.dcdl',
+    entryPath: 'main.dcdl',
     files: {
       'main.dcdl': `let
     schema = import "./schemas/pipeline.dcdl";
@@ -276,6 +279,7 @@ privacy = ["redact_ip", "hash_user_id"];
     id: 'edge-cdn-policy',
     title: 'Edge CDN routing policy',
     activePath: 'main.dcdl',
+    entryPath: 'main.dcdl',
     files: {
       'main.dcdl': `let
     schema = import "./schemas/edge.dcdl";
@@ -340,6 +344,7 @@ StrictHeaders = {
     id: 'incident-escalation',
     title: 'Incident escalation policy',
     activePath: 'main.dcdl',
+    entryPath: 'main.dcdl',
     files: {
       'main.dcdl': `let
     schema = import "./schemas/oncall.dcdl";
diff --git a/site/decodal-site/src/scripts/playground.js b/site/decodal-site/src/scripts/playground.js
index f76166c..44128e6 100644
--- a/site/decodal-site/src/scripts/playground.js
+++ b/site/decodal-site/src/scripts/playground.js
@@ -7,7 +7,7 @@ import { keymap } from '@codemirror/view';
 import { decodal } from 'decodal-codemirror';
 import { playgroundExamples } from './playground-examples.js';
 
-const STORAGE_KEY = 'decodal-playground-project-v1';
+const STORAGE_KEY = 'decodal-playground-project-v2';
 const starterProject = playgroundExamples[0];
 
 const editorHost = document.getElementById('editor');
@@ -90,6 +90,7 @@ for (const example of playgroundExamples) {
 exampleSelect.value = starterProject.id;
 
 setActiveFile(project.activePath);
+updateRunLabel();
 renderFileTree();
 
 function loadProject() {
@@ -98,12 +99,22 @@ function loadProject() {
     if (stored && stored.files && typeof stored.activePath === 'string') {
       const files = normalizeFiles(stored.files);
       const activePath = files[stored.activePath] === undefined ? Object.keys(files)[0] : stored.activePath;
-      if (activePath) return { files, activePath };
+      if (activePath) {
+        const storedEntryPath = typeof stored.entryPath === 'string' ? normalizePath(stored.entryPath) : '';
+        const entryPath = files[storedEntryPath] === undefined
+          ? files['main.dcdl'] === undefined ? activePath : 'main.dcdl'
+          : storedEntryPath;
+        return { files, activePath, entryPath };
+      }
     }
   } catch (_error) {
     // Fall back to the starter project.
   }
-  return { files: cloneFiles(starterProject.files), activePath: starterProject.activePath };
+  return {
+    files: cloneFiles(starterProject.files),
+    activePath: starterProject.activePath,
+    entryPath: starterProject.entryPath ?? starterProject.activePath,
+  };
 }
 
 function cloneFiles(files) {
@@ -127,6 +138,7 @@ function loadExampleProject(exampleId) {
   const example = playgroundExamples.find((item) => item.id === exampleId) ?? starterProject;
   project.files = cloneFiles(example.files);
   project.activePath = example.activePath;
+  project.entryPath = example.entryPath ?? example.activePath;
   exampleSelect.value = example.id;
   setActiveFile(project.activePath);
   output.textContent = '';
@@ -166,16 +178,27 @@ function setActiveFile(path) {
   }
   project.activePath = normalized;
   setEditorText(project.files[normalized]);
-  activeFile.textContent = normalized;
+  activeFile.textContent = normalized === project.entryPath ? `${normalized} (entry)` : normalized;
   deleteFile.disabled = Object.keys(project.files).length <= 1;
   renderFileTree();
+  updateRunLabel();
   saveProject();
 }
 
+function updateRunLabel() {
+  const entryPath = project.files[project.entryPath] === undefined ? project.activePath : project.entryPath;
+  project.entryPath = entryPath;
+  run.textContent = `Run ${entryPath}`;
+  run.title = `Materialize ${entryPath}`;
+}
+
 function execute() {
   project.files[project.activePath] = getEditorText();
+  const entryPath = project.files[project.entryPath] === undefined ? project.activePath : project.entryPath;
+  project.entryPath = entryPath;
+  updateRunLabel();
   saveProject();
-  const result = JSON.parse(evaluateProject(project.activePath, JSON.stringify(project.files)));
+  const result = JSON.parse(evaluateProject(entryPath, JSON.stringify(project.files)));
   output.textContent = result.ok ? result.output : result.error;
   output.classList.toggle('error', !result.ok);
 }
@@ -224,8 +247,8 @@ function renderTreeList(children) {
       const button = document.createElement('button');
       button.type = 'button';
       button.className = child.path === project.activePath ? 'file active' : 'file';
-      button.textContent = child.name;
-      button.title = child.path;
+      button.textContent = child.path === project.entryPath ? `${child.name} *` : child.name;
+      button.title = child.path === project.entryPath ? `${child.path} (entry point)` : child.path;
       button.addEventListener('click', () => setActiveFile(child.path));
       item.append(button);
     } else {
@@ -276,5 +299,8 @@ deleteFile.addEventListener('click', () => {
   if (Object.keys(project.files).length <= 1) return;
   if (!confirm(`Delete ${project.activePath}?`)) return;
   delete project.files[project.activePath];
+  if (project.files[project.entryPath] === undefined) {
+    project.entryPath = Object.keys(project.files).sort()[0];
+  }
   setActiveFile(Object.keys(project.files).sort()[0]);
 });