From fa2f839cbd4ab27a45558dd9b34343db4aa34653 Mon Sep 17 00:00:00 2001
From: Sameh Khamis <sameh@halfpixel.ai>
Date: Tue, 15 Sep 2026 08:12:13 -0700
Subject: [PATCH] fix: validate feature services before allocating scene owners

---
 src/app/operations.js       | 14 ++++++++------
 src/app/operations.test.mjs | 19 +++++++++++++++++++
 2 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/src/app/operations.js b/src/app/operations.js
index f5e93c78c..f5104e960 100644
--- a/src/app/operations.js
+++ b/src/app/operations.js
@@ -1,3 +1,4 @@
+import { requireFeatureSource } from '../sources/featureSource.js';
 import { createOverpassFeatureSource } from '../sources/overpassFeatures.js';
 import { createSurfaceServices } from './surfaceServices.js';
 import { createAnnotationResolver } from '../annotations/resolver.js';
@@ -14,17 +15,18 @@ export function createApplicationOperations({ requests, signal, eventTarget }) {
     if (typeof requests?.[name]?.[method] !== 'function')
       throw new TypeError(`Missing application request service: ${name}`);
   }
+  const features = requireFeatureSource(
+    requests.features ??
+      createOverpassFeatureSource({
+        boundarySource: requests.boundaries,
+        signal,
+      }),
+  );
   const surface = createSurfaceServices({
     terrainSource: requests.terrain,
     signal,
     eventTarget,
   });
-  const features =
-    requests.features ??
-    createOverpassFeatureSource({
-      boundarySource: requests.boundaries,
-      signal,
-    });
   const annotationResolver = createAnnotationResolver({
     featureSource: features,
     signal,
diff --git a/src/app/operations.test.mjs b/src/app/operations.test.mjs
index fa1424750..6a8ca8966 100644
--- a/src/app/operations.test.mjs
+++ b/src/app/operations.test.mjs
@@ -163,3 +163,22 @@ test('annotation lookup and cached outlines use the supplied source independentl
     { name: 'AbortError' },
   );
 });
+
+test('invalid feature adapters fail before surface listeners are installed', () => {
+  let installed = 0;
+  assert.throws(
+    () =>
+      createApplicationOperations({
+        signal: new AbortController().signal,
+        requests: { ...requests({ getHeights: async () => [] }), features: {} },
+        eventTarget: {
+          addEventListener() {
+            installed++;
+          },
+          removeEventListener() {},
+        },
+      }),
+    /Missing feature operation/,
+  );
+  assert.equal(installed, 0);
+});