Fix structured attachment rendering

src/web-dashboard-attachments.test.ts

@@ -0,0 +1,46 @@
+import fs from 'fs';
+import os from 'os';
+import path from 'path';
+
+import { afterEach, describe, expect, it } from 'vitest';
+
+import { createWebDashboardHandler } from './web-dashboard-server.js';
+
+const ONE_PIXEL_PNG = Buffer.from(
+  'iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mP8/x8AAwMCAO+/p9sAAAAASUVORK5CYII=',
+  'base64',
+);
+
+const tempFiles: string[] = [];
+
+afterEach(() => {
+  for (const file of tempFiles.splice(0)) {
+    fs.rmSync(file, { force: true });
+  }
+});
+
+describe('web dashboard attachment previews', () => {
+  it('serves validated direct temp image attachments', async () => {
+    const filePath = path.join(
+      os.tmpdir(),
+      `bar-chart-label-fit-playwright-${Date.now()}.png`,
+    );
+    fs.writeFileSync(filePath, ONE_PIXEL_PNG);
+    tempFiles.push(filePath);
+    const handler = createWebDashboardHandler({
+      readStatusSnapshots: () => [],
+      getTasks: () => [],
+      getPairedTasks: () => [],
+    });
+
+    const response = await handler(
+      new Request(
+        `http://localhost/api/attachments?path=${encodeURIComponent(filePath)}`,
+      ),
+    );
+
+    expect(response.status).toBe(200);
+    expect(response.headers.get('content-type')).toBe('image/png');
+    expect(Buffer.from(await response.arrayBuffer())).toEqual(ONE_PIXEL_PNG);
+  });
+});