fix: strip XML preamble in devvit create icons

packages/cli/src/commands/create/icons.test.ts

@@ -0,0 +1,41 @@
+import { describe, expect, it } from 'vitest';
+
+import { stripXmlPreamble } from './icons.js';
+
+describe('stripXmlPreamble', () => {
+  it('strips <?xml?> declaration', () => {
+    const input = '<?xml version="1.0" encoding="UTF-8"?>\n<svg viewBox="0 0 24 24"></svg>';
+    expect(stripXmlPreamble(input)).toBe('<svg viewBox="0 0 24 24"></svg>');
+  });
+
+  it('strips <!DOCTYPE> declaration', () => {
+    const input =
+      '<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">\n<svg></svg>';
+    expect(stripXmlPreamble(input)).toBe('<svg></svg>');
+  });
+
+  it('strips XML comments before <svg>', () => {
+    const input = '<!-- generated by Inkscape -->\n<svg></svg>';
+    expect(stripXmlPreamble(input)).toBe('<svg></svg>');
+  });
+
+  it('strips combined preamble (<?xml?> + <!DOCTYPE> + comment)', () => {
+    const input = [
+      '<?xml version="1.0" encoding="UTF-8"?>',
+      '<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">',
+      '<!-- Created with Illustrator -->',
+      '<svg viewBox="0 0 100 100"></svg>',
+    ].join('\n');
+    expect(stripXmlPreamble(input)).toBe('<svg viewBox="0 0 100 100"></svg>');
+  });
+
+  it('returns input unchanged when no preamble exists', () => {
+    const input = '<svg viewBox="0 0 24 24"><path d="M0 0"/></svg>';
+    expect(stripXmlPreamble(input)).toBe(input);
+  });
+
+  it('handles leading whitespace before <svg>', () => {
+    const input = '  \n  <svg></svg>';
+    expect(stripXmlPreamble(input)).toBe('<svg></svg>');
+  });
+});

packages/cli/src/commands/create/icons.ts

@@ -9,6 +9,11 @@ import { dirExists } from '../../util/files.js';
 
 type SvgAsset = { name: string; contents: string };
 
+/** Strip XML preamble (<?xml?>, <!DOCTYPE>, comments) before the <svg> tag. */
+export function stripXmlPreamble(contents: string): string {
+  return contents.replace(/^[\s\S]*?(<svg)/i, '$1');
+}
+
 // TODO: When Blocks support is fully removed, this command can be removed as well, since icons will
 //  be loaded directly in the webview once we're fully in a Devvit Web world.
 export default class Icons extends DevvitCommand {
@@ -58,7 +63,7 @@ export default class Icons extends DevvitCommand {
       assets.map(async (asset) => {
         const name = path.relative(assetsPath, asset);
         const contents = await fsp.readFile(asset, 'utf-8');
-        return { name, contents };
+        return { name, contents: stripXmlPreamble(contents) };
       })
     );
   }