snapshot of https://github.com/tldraw/tldraw.git (main, 2026-09-23; blobs > 131072B omitted)

apps/docs/utils/asset-url.ts

@@ -0,0 +1,40 @@
+/**
+ * Resolves root-relative static URLs (`/images/...`, `/favicon.svg`) to absolute URLs when the
+ * docs app is deployed with `assetPrefix` (e.g. proxied via tldraw.dev per RUNBOOK). Next applies
+ * `assetPrefix` to `/_next/*` automatically; strings in MDX remain plain paths unless we prefix them.
+ *
+ * Precedence (first hit wins):
+ * 1. `ASSET_PREFIX` — server/build (Vercel / CI)
+ * 2. `NEXT_PUBLIC_ASSET_PREFIX` — same value inlined for client bundles when needed
+ * 3. `NEXT_PUBLIC_DOCS_ASSET_PREFIX` — alias for ops clarity (same behavior as #2)
+ * 4. `VERCEL_URL` — preview deployments
+ * 5. `NEXT_PUBLIC_VERCEL_URL` — client-side fallback for preview hostname
+ */
+function resolveAssetOrigin(): string | undefined {
+	const explicit =
+		process.env.ASSET_PREFIX?.trim() ||
+		process.env.NEXT_PUBLIC_ASSET_PREFIX?.trim() ||
+		process.env.NEXT_PUBLIC_DOCS_ASSET_PREFIX?.trim()
+	if (explicit) return explicit.replace(/\/$/, '')
+
+	const vercelUrl = process.env.VERCEL_URL?.trim() || process.env.NEXT_PUBLIC_VERCEL_URL?.trim()
+	if (vercelUrl) {
+		const host = vercelUrl.replace(/^https?:\/\//, '')
+		return `https://${host}`
+	}
+
+	return undefined
+}
+
+/**
+ * Prefix a root-relative public/static path for the current docs deployment.
+ * Use for MDX images, icons in metadata, and any `/…` URL that must load from the docs origin
+ * when the site is served behind a proxy or alternate host.
+ */
+export function assetUrl(path: string): string {
+	if (path.startsWith('//')) return path
+	if (!path.startsWith('/')) return path
+	const origin = resolveAssetOrigin()
+	if (!origin) return path
+	return `${origin}${path}`
+}