feat: implement rewriteExerciseLinks function for relative exercise links

Author: jung-thomas

docs/.vitepress/plugins/md-expand-tutorials.test.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect, beforeEach } from 'vitest'
-import { expandTutorialsInSource } from './md-expand-tutorials.js'
+import { expandTutorialsInSource, rewriteExerciseLinks } from './md-expand-tutorials.js'
 
 // Simulates the in-memory cache for testing (no Vite context needed)
 const fakeCache = new Map<string, string>([
@@ -81,3 +81,20 @@ describe('expandTutorialsInSource', () => {
     expect(result).toBe(src)
   })
 })
+
+describe('rewriteExerciseLinks', () => {
+  it('rewrites ../exN/README.md to /exercises/exN/', () => {
+    const src = '👉 [Exercise 2](../ex2/README.md)'
+    expect(rewriteExerciseLinks(src)).toBe('👉 [Exercise 2](/exercises/ex2/)')
+  })
+
+  it('rewrites all occurrences in a document', () => {
+    const src = 'See [ex1](../ex1/README.md) and [ex8](../ex8/README.md).'
+    expect(rewriteExerciseLinks(src)).toBe('See [ex1](/exercises/ex1/) and [ex8](/exercises/ex8/).')
+  })
+
+  it('does not modify unrelated links', () => {
+    const src = '[GitHub](https://github.com) and [prereqs](../prerequisites.md)'
+    expect(rewriteExerciseLinks(src)).toBe(src)
+  })
+})

docs/.vitepress/plugins/md-expand-tutorials.ts

@@ -4,6 +4,16 @@ import { getTutorialContent } from './external-tutorials.js'
 /** URL prefix all SAP tutorial links share. */
 const SAP_TUTORIAL_PATTERN = /https:\/\/developers\.sap\.com\/tutorials\/([a-z0-9-]+)\.html/g
 
+/**
+ * Rewrites relative exercise README links to VitePress clean URLs.
+ * e.g. ../ex2/README.md → /exercises/ex2/
+ * These links are valid on GitHub but 404 in the VitePress site because
+ * the wrapper pages live at docs/exercises/exN/index.md, not README.md.
+ */
+export function rewriteExerciseLinks(src: string): string {
+  return src.replace(/\.\.\/(ex\d)\/README\.md/g, '/exercises/$1/')
+}
+
 /**
  * Performs pre-parse source substitution on a single markdown source string.
  * Exported separately so it can be unit-tested without a MarkdownIt instance.
@@ -63,7 +73,8 @@ export function expandTutorialsInSource(
 export function expandTutorialsPlugin(md: MarkdownIt): void {
   const originalRender = md.render.bind(md)
   md.render = function (src: string, env?: unknown): string {
-    const expanded = expandTutorialsInSource(src, getTutorialContent)
+    const rewritten = rewriteExerciseLinks(src)
+    const expanded = expandTutorialsInSource(rewritten, getTutorialContent)
     return originalRender(expanded, env)
   }
 }