fix: canonical links (#214)

* fix: canonical links

* fix: transform page data

Author: sriramveeraghanta

docs/.vitepress/config.mts

@@ -109,9 +109,6 @@ export default withMermaid(defineConfig({
     ['meta', { name: 'keywords', content: 'plane, api, self-hosting, project management, developer documentation, kubernetes, docker, rest api, webhooks, plane api' }],
     ['meta', { name: 'theme-color', content: '#3b82f6' }],
 
-    // SEO: Canonical URL
-    ['link', { rel: 'canonical', href: 'https://developers.plane.so' }],
-
     // Open Graph meta tags
     ['meta', { property: 'og:type', content: 'website' }],
     ['meta', { property: 'og:title', content: 'Developer documentation | Plane' }],
@@ -126,6 +123,19 @@ export default withMermaid(defineConfig({
     ['meta', { name: 'twitter:image', content: 'https://media.docs.plane.so/logo/og-docs.webp' }],
   ],
 
+  transformPageData(pageData) {
+    const head = pageData.frontmatter.head ??= []
+    const hasCanonical = head.some(
+      ([tag, attrs]) => tag === 'link' && attrs?.rel === 'canonical'
+    )
+    if (!hasCanonical) {
+      const canonicalUrl = `https://developers.plane.so/${pageData.relativePath}`
+        .replace(/index\.md$/, '')
+        .replace(/\.md$/, '')
+      head.push(['link', { rel: 'canonical', href: canonicalUrl }])
+    }
+  },
+
   themeConfig: {
     siteTitle: false,
     logo: {