fix(director): reject cancellation during the final asset stream read

src/director/packs/asset-stream-cancellation.test.mjs

@@ -0,0 +1,42 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { createAssetDirectorySource } from './source.js';
+test('cancellation during the terminating read cannot return a scene asset', async () => {
+  for (const cancel of [true, false]) {
+    const controller = new AbortController();
+    let reads = 0,
+      cancelled = 0,
+      released = 0;
+    const source = createAssetDirectorySource({
+      baseUrl: 'https://fixture.example/assets/',
+      fetchImpl: async () => ({
+        ok: true,
+        headers: new Headers({ 'content-type': 'application/octet-stream' }),
+        body: {
+          getReader() {
+            return {
+              async read() {
+                reads++;
+                if (reads === 1)
+                  return { done: false, value: new Uint8Array([1, 2]) };
+                if (cancel) controller.abort();
+                return { done: true };
+              },
+              async cancel() {
+                cancelled++;
+              },
+              releaseLock() {
+                released++;
+              },
+            };
+          },
+        },
+      }),
+    });
+    const pending = source({ path: 'scene.bin', signal: controller.signal });
+    if (cancel) await assert.rejects(pending, { name: 'AbortError' });
+    else assert.deepEqual([...(await pending).bytes], [1, 2]);
+    assert.equal(cancelled, 1);
+    assert.equal(released, 1);
+  }
+});

src/director/packs/source.js

@@ -41,6 +41,7 @@ export function createAssetDirectorySource({
       for (;;) {
         signal?.throwIfAborted();
         const { done, value } = await reader.read();
+        signal?.throwIfAborted();
         if (done) break;
         length += value.byteLength;
         if (length > maxBytes) throw new Error('Asset exceeds byte limit');