Add built-in integrations conditionally (#796)

Co-authored-by: Chris Swithinbank <swithinbank@gmail.com>

3 files changed, 22 insertions, 16 deletions

diff --git a/.changeset/happy-tips-burn.md b/.changeset/happy-tips-burn.md
new file mode 100644
index 00000000..6cffe4d9
--- /dev/null
+++ b/.changeset/happy-tips-burn.md
@@ -0,0 +1,11 @@
+---
+'@astrojs/starlight': minor
+---
+
+Add the `@astrojs/sitemap` and `@astrojs/mdx` integrations only if they are not detected in the Astro configuration.
+
+⚠️ **BREAKING CHANGE** The minimum supported version of Astro is now v3.2.0. Make sure you update Astro at the same time as updating Starlight:
+
+```sh
+npm install astro@latest
+```
diff --git a/packages/starlight/index.ts b/packages/starlight/index.ts
index 50e37d04..a52b994f 100644
--- a/packages/starlight/index.ts
+++ b/packages/starlight/index.ts
@@ -10,7 +10,7 @@ import { errorMap } from './utils/error-map';
 import { StarlightConfigSchema, type StarlightUserConfig } from './utils/user-config';
 import { rehypeRtlCodeSupport } from './integrations/code-rtl-support';
 
-export default function StarlightIntegration(opts: StarlightUserConfig): AstroIntegration[] {
+export default function StarlightIntegration(opts: StarlightUserConfig): AstroIntegration {
 	const parsedConfig = StarlightConfigSchema.safeParse(opts, { errorMap });
 
 	if (!parsedConfig.success) {
@@ -34,7 +34,15 @@ export default function StarlightIntegration(opts: StarlightUserConfig): AstroIn
 					pattern: '[...slug]',
 					entryPoint: '@astrojs/starlight/index.astro',
 				});
+				const integrations: AstroIntegration[] = [];
+				if (!config.integrations.find(({ name }) => name === '@astrojs/sitemap')) {
+					integrations.push(starlightSitemap(userConfig));
+				}
+				if (!config.integrations.find(({ name }) => name === '@astrojs/mdx')) {
+					integrations.push(mdx());
+				}
 				const newConfig: AstroUserConfig = {
+					integrations,
 					vite: {
 						plugins: [vitePluginStarlightUserConfig(userConfig, config)],
 					},
@@ -50,19 +58,6 @@ export default function StarlightIntegration(opts: StarlightUserConfig): AstroIn
 				updateConfig(newConfig);
 			},
 
-			'astro:config:done': ({ config }) => {
-				const integrations = config.integrations.map(({ name }) => name);
-				for (const builtin of ['@astrojs/mdx', '@astrojs/sitemap']) {
-					if (integrations.filter((name) => name === builtin).length > 1) {
-						throw new Error(
-							`Found more than one instance of ${builtin}.\n` +
-								`Starlight includes ${builtin} by default.\n` +
-								'Please remove it from your integrations array in astro.config.mjs'
-						);
-					}
-				}
-			},
-
 			'astro:build:done': ({ dir }) => {
 				const targetDir = fileURLToPath(dir);
 				const cwd = dirname(fileURLToPath(import.meta.url));
@@ -78,5 +73,5 @@ export default function StarlightIntegration(opts: StarlightUserConfig): AstroIn
 		},
 	};
 
-	return [starlightSitemap(userConfig), Starlight, mdx()];
+	return Starlight;
 }
diff --git a/packages/starlight/package.json b/packages/starlight/package.json
index 5e3dfc63..dc9f928a 100644
--- a/packages/starlight/package.json
+++ b/packages/starlight/package.json
@@ -32,7 +32,7 @@
     "./404.astro": "./404.astro"
   },
   "peerDependencies": {
-    "astro": "^3.0.0"
+    "astro": "^3.2.0"
   },
   "devDependencies": {
     "@types/node": "^18.16.19",