fix: properly prefix endpoint path with base in SSR (#7047)

* fix: properly prefix endpoint path with base in SSR

* chore: sssss

* chore: changeset

.changeset/clean-carpets-battle.md

@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fix `/_image` endpoint not being prefixed with the `base` path in build SSR

packages/astro/src/assets/services/service.ts

@@ -1,4 +1,5 @@
 import { AstroError, AstroErrorData } from '../../core/errors/index.js';
+import { joinPaths } from '../../core/path.js';
 import { VALID_OPTIMIZABLE_FORMATS } from '../consts.js';
 import { isESMImportedImage } from '../internal.js';
 import type { ImageOutputFormat, ImageTransform } from '../types.js';
@@ -195,7 +196,7 @@ export const baseService: Omit<LocalImageService, 'transform'> = {
 		options.quality && searchParams.append('q', options.quality.toString());
 		options.format && searchParams.append('f', options.format);
 
-		return '/_image?' + searchParams;
+		return joinPaths(import.meta.env.BASE_URL, '/_image?') + searchParams;
 	},
 	parseURL(url) {
 		const params = url.searchParams;

packages/astro/test/core-image.test.js

@@ -447,6 +447,27 @@ describe('astro:image', () => {
 			expect(src.length).to.be.greaterThan(0);
 			expect(src.startsWith('/blog')).to.be.true;
 		});
+
+		it('has base path prefix in SSR', async () => {
+			const fixtureWithBase = await loadFixture({
+				root: './fixtures/core-image-ssr/',
+				output: 'server',
+				adapter: testAdapter(),
+				experimental: {
+					assets: true,
+				},
+				base: '/blog',
+			});
+			await fixtureWithBase.build();
+			const app = await fixtureWithBase.loadTestAdapterApp();
+			const request = new Request('http://example.com/blog/');
+			const response = await app.render(request);
+			expect(response.status).to.equal(200);
+			const html = await response.text();
+			const $ = cheerio.load(html);
+			const src = $('#local img').attr('src');
+			expect(src.startsWith('/blog')).to.be.true;
+		});
 	});
 
 	describe('build ssg', () => {