fix: proxy should ignore /opengraph-image path, not redirect it

Author: jakejarvis

lib/middleware.test.ts

@@ -1,10 +1,16 @@
-/* @vitest-environment node */
 import { describe, expect, it } from "vitest";
 import { getProxyAction } from "./middleware";
 
 describe("getProxyAction", () => {
   it("skips root path", () => {
-    expect(getProxyAction("/")).toEqual({ type: "skip" });
+    expect(getProxyAction("/")).toBeNull();
+  });
+
+  it("skips opengraph-image route", () => {
+    // This is essential for the dynamic OG image route [domain]/opengraph-image.tsx
+    expect(getProxyAction("/example.com/opengraph-image")).toBeNull();
+    // Also check nested paths just in case, though our routing is [domain]
+    expect(getProxyAction("/https://example.com/opengraph-image")).toBeNull();
   });
 
   it("matches clean domain", () => {
@@ -56,11 +62,11 @@ describe("getProxyAction", () => {
   });
 
   it("skips IPv6 literals", () => {
-    expect(getProxyAction("/[::1]")).toEqual({ type: "skip" });
+    expect(getProxyAction("/[::1]")).toBeNull();
   });
 
   it("skips IPv6 literals with port", () => {
-    expect(getProxyAction("/[::1]:8080")).toEqual({ type: "skip" });
+    expect(getProxyAction("/[::1]:8080")).toBeNull();
   });
 
   it("redirects port on valid domain", () => {
@@ -74,7 +80,7 @@ describe("getProxyAction", () => {
 
   it("skips invalid domains", () => {
     // toRegistrableDomain returns null for "invalid-domain"
-    expect(getProxyAction("/invalid-domain")).toEqual({ type: "skip" });
+    expect(getProxyAction("/invalid-domain")).toBeNull();
   });
 
   it("redirects messy input", () => {

lib/middleware.ts

@@ -7,18 +7,26 @@ import { toRegistrableDomain } from "@/lib/domain-server";
 export const SCHEME_PREFIX_REGEX = /^https?[:/]+([^/]+)/i;
 
 export type ProxyAction =
-  | { type: "skip" }
   | { type: "match" }
-  | { type: "redirect"; destination: string };
+  | { type: "redirect"; destination: string }
+  | null;
 
 /**
  * Pure function to decide the proxy action based on the URL path.
  * Decoupled from NextRequest/NextResponse for easier testing.
+ * Returns null to skip processing (e.g. invalid domains, root path, etc).
  */
 export function getProxyAction(path: string): ProxyAction {
   // Fast path: root path or empty
   if (path.length <= 1) {
-    return { type: "skip" };
+    return null;
+  }
+
+  // Special case for OpenGraph images: /example.com/opengraph-image
+  // This pattern is used by Next.js OG image generation for the dynamic route [domain]/opengraph-image.tsx
+  // We should skip middleware processing for this specific suffix to allow the route to handle it.
+  if (path.endsWith("/opengraph-image")) {
+    return null;
   }
 
   // 1. Get raw input (remove leading slash)
@@ -61,7 +69,7 @@ export function getProxyAction(path: string): ProxyAction {
   // 6. Strip Port
   // IPv6 literals in brackets (e.g. [::1]) are not supported.
   if (authority.includes("[") || authority.includes("]")) {
-    return { type: "skip" };
+    return null;
   }
 
   // Safe to split on colon as valid domains don't contain colons
@@ -70,14 +78,14 @@ export function getProxyAction(path: string): ProxyAction {
   candidate = authority.trim();
 
   if (!candidate) {
-    return { type: "skip" };
+    return null;
   }
 
   // 7. Validate and Normalize
   // This will return null for invalid domains, including IPs if rdapper handles them as such.
   const registrable = toRegistrableDomain(candidate);
   if (!registrable) {
-    return { type: "skip" };
+    return null;
   }
 
   // 8. Redirect if necessary
@@ -96,20 +104,25 @@ export function getProxyAction(path: string): ProxyAction {
 export function handleProxyRequest(request: NextRequest) {
   const action = getProxyAction(request.nextUrl.pathname);
 
-  const headers = new Headers();
-  headers.set("x-middleware-decision", action.type);
+  if (action === null) {
+    return NextResponse.next();
+  }
 
   if (action.type === "redirect") {
     const url = request.nextUrl.clone();
     url.pathname = action.destination;
     url.search = "";
     url.hash = "";
     return NextResponse.redirect(url, {
-      headers,
+      headers: {
+        "x-middleware-decision": action.type,
+      },
     });
   }
 
   return NextResponse.next({
-    headers,
+    headers: {
+      "x-middleware-decision": action.type,
+    },
   });
 }