feat: PostHog on the docs, through a same-site /relay proxy

docusaurus.config.mjs

@@ -16,6 +16,15 @@ const config = {
   title: 't1 Docs',
   tagline: 'Documentation for t1, the permissionless credit protocol for DeFi.',
   url: 'https://docs.t1protocol.com',
+  // PostHog project "t1" (shared with t1protocol.com, told apart by $host), sent
+  // through this site's own /relay proxy (netlify.toml) so ad blockers don't drop it.
+  headTags: [
+    {
+      tagName: 'script',
+      attributes: {},
+      innerHTML: 'if(!/^(localhost|127\\.0\\.0\\.1)$/.test(location.hostname)){!function(t,e){var o,n,p,r;e.__SV||(window.posthog=e,e._i=[],e.init=function(i,s,a){function g(t,e){var o=e.split(".");2==o.length&&(t=t[o[0]],e=o[1]),t[e]=function(){t.push([e].concat(Array.prototype.slice.call(arguments,0)))}}(p=t.createElement("script")).type="text/javascript",p.crossOrigin="anonymous",p.async=!0,p.src=s.api_host.replace(".i.posthog.com","-assets.i.posthog.com")+"/static/array.js",(r=t.getElementsByTagName("script")[0]).parentNode.insertBefore(p,r);var u=e;for(void 0!==a?u=e[a]=[]:a="posthog",u.people=u.people||[],u.toString=function(t){var e="posthog";return"posthog"!==a&&(e+="."+a),t||(e+=" (stub)"),e},u.people.toString=function(){return u.toString(1)+".people (stub)"},o="init capture register identify reset get_distinct_id captureException".split(" "),n=0;n<o.length;n++)g(u,o[n]);e._i.push([i,s,a])},e.__SV=1)}(document,window.posthog||[]);posthog.init("phc_ncQxnKfh4f3u4NFQW8GVC9sxKsNsR7WBqbFEjg6zdrtS",{api_host:location.origin+"/relay",ui_host:"https://us.posthog.com",capture_pageview:"history_change",capture_exceptions:true});}',
+    },
+  ],
   baseUrl: '/',
   onBrokenLinks: 'warn',
   onBrokenMarkdownLinks: 'warn',

netlify.toml

@@ -1,3 +1,17 @@
+# Same-origin proxy for PostHog (the headTags script in docusaurus.config.mjs),
+# also used by t1protocol.com, which Firebase Hosting cannot proxy itself.
+[[redirects]]
+from = "/relay/static/*"
+to = "https://us-assets.i.posthog.com/static/:splat"
+status = 200
+force = true
+
+[[redirects]]
+from = "/relay/*"
+to = "https://us.i.posthog.com/:splat"
+status = 200
+force = true
+
 [[redirects]]
 from = "/concepts/*"
 to = "/intro/:splat"