integration: clear cached Markdown when the options change

packages/starlight-codeblocks/src/integration.ts

@@ -1,3 +1,4 @@
+import { createHash } from 'node:crypto';
 import { existsSync } from 'node:fs';
 import { fileURLToPath } from 'node:url';
 import type { ExpressiveCodePlugin } from '@expressive-code/core';
@@ -49,8 +50,14 @@ export function codeblocksIntegration({
       'astro:config:setup'({ command, config, updateConfig, injectScript, logger }) {
         // The shapes `isSatteriProcessor()` and `isUnifiedProcessor()` check, without depending on either package.
         const processor = config.markdown.processor as
-          | { name?: string; options?: { mdastPlugins?: unknown[]; remarkPlugins?: unknown[] } }
+          | {
+              name?: string;
+              options?: { mdastPlugins?: unknown[]; remarkPlugins?: unknown[]; starlightCodeblocks?: string };
+            }
           | undefined;
+        // The content layer keeps rendered Markdown until its digest of the Astro config changes. That digest
+        // skips integrations and functions but covers these options, which both processors otherwise ignore.
+        if (processor?.options) processor.options.starlightCodeblocks = optionsDigest(options);
         if (processor?.name === 'unified') {
           processor.options?.remarkPlugins?.push(remarkFromSatteri(mdastPlugins(options, logger)));
         } else processor?.options?.mdastPlugins?.push(...mdastPlugins(options, logger));
@@ -81,6 +88,12 @@ export function codeblocksIntegration({
   };
 }
 
+const optionsDigest = (options: ResolvedOptions) =>
+  createHash('sha256')
+    .update(JSON.stringify(options, (_, value) => (typeof value === 'function' ? String(value) : value)))
+    .digest('base64url')
+    .slice(0, 16);
+
 /** The site's `ec.config.mjs`, imported fresh, as Expressive Code does. */
 export async function loadEcConfig(root: URL) {
   const url = new URL('./ec.config.mjs', root);

packages/starlight-codeblocks/test/astro.test.ts

@@ -11,7 +11,10 @@ import { mdastPlugins, restoreDirectives } from '../src/satteri/index.ts';
 
 afterEach(() => setRegistry(undefined));
 
-type Processor = { name: string; options: { features?: { directive?: boolean }; mdastPlugins: unknown[] } };
+type Processor = {
+  name: string;
+  options: { features?: { directive?: boolean }; mdastPlugins: unknown[]; starlightCodeblocks?: string };
+};
 
 async function setup(options: AstroCodeblocksOptions = {}, ecConfig?: string, others: string[] = []) {
   const root = mkdtempSync(join(tmpdir(), 'scb-'));
@@ -57,6 +60,13 @@ test('changes nothing outside code blocks unless the site turns on code tabs or
   expect(getRegistry()?.options).toMatchObject({ codeTabs: false, inlineHighlighting: false });
 });
 
+test('puts a digest of its options in the hashed Astro config, so that a change clears rendered Markdown', async () => {
+  const digest = async (options: AstroCodeblocksOptions) =>
+    (await setup(options)).processor.options.starlightCodeblocks;
+  expect(await digest({})).toBe(await digest({}));
+  expect(await digest({ footnotes: false })).not.toBe(await digest({}));
+});
+
 test('adds the inline code stylesheet on every page, and never the API card page styles', async () => {
   const { scripts } = await setup({ inlineHighlighting: {} });
   expect(scripts).toEqual(['import "virtual:starlight-codeblocks/inline-code.css";']);