feat: add proxy to url shortner

app/api/share/route.ts

@@ -0,0 +1,57 @@
+import { NextRequest, NextResponse } from "next/server";
+
+// Same-origin proxy for the URL-shortener create endpoint. Client components
+// (text-selection toolbar, share modal) call /api/share so the actual BFF
+// request happens server-side — this is the only way to read `BFF_URL`,
+// since Next.js does not expose non-`NEXT_PUBLIC_` env vars to the browser
+// bundle. Same pattern as /api/search.
+const BFF_BASE = process.env.BFF_URL || "http://localhost:8080";
+
+export async function POST(request: NextRequest) {
+  let body: unknown;
+  try {
+    body = await request.json();
+  } catch {
+    return NextResponse.json(
+      { success: false, error: { code: 400, message: "invalid JSON body" } },
+      { status: 400 },
+    );
+  }
+
+  const url =
+    body && typeof body === "object" && "url" in body
+      ? (body as { url: unknown }).url
+      : null;
+  if (typeof url !== "string" || !url.startsWith("/")) {
+    return NextResponse.json(
+      {
+        success: false,
+        error: { code: 400, message: "url must be a same-site path" },
+      },
+      { status: 400 },
+    );
+  }
+
+  try {
+    const res = await fetch(new URL("/api/v1/share", BFF_BASE).toString(), {
+      method: "POST",
+      headers: {
+        "Content-Type": "application/json",
+        Accept: "application/json",
+      },
+      body: JSON.stringify({ url }),
+      cache: "no-store",
+    });
+
+    const text = await res.text();
+    return new NextResponse(text, {
+      status: res.status,
+      headers: { "Content-Type": "application/json" },
+    });
+  } catch {
+    return NextResponse.json(
+      { success: false, error: { code: 502, message: "BFF unreachable" } },
+      { status: 502 },
+    );
+  }
+}

lib/bff.ts

@@ -122,40 +122,3 @@ export async function bffList<T>(
   return result ?? [];
 }
 
-/**
- * POST JSON to the BFF API. Used for mutations like the URL shortener; does
- * not participate in Next.js caching (each POST is a unique side-effect).
- *
- * Same envelope-unwrapping behavior as bff(): returns the inner `data`
- * value, throws BffError on non-2xx.
- */
-export async function bffPost<T>(
-  path: string,
-  body: Record<string, unknown>,
-): Promise<T> {
-  const url = apiUrl(path);
-
-  const res = await fetch(url, {
-    method: "POST",
-    headers: {
-      Accept: "application/json",
-      "Content-Type": "application/json",
-    },
-    body: JSON.stringify(body),
-    cache: "no-store",
-  });
-
-  if (!res.ok) {
-    const text = await res.text().catch(() => "");
-    throw new BffError(
-      res.status,
-      `BFF ${res.status} POST ${path}: ${text.slice(0, 200)}`,
-    );
-  }
-
-  const json = await res.json();
-  if (json && typeof json === "object" && "data" in json) {
-    return json.data as T;
-  }
-  return json as T;
-}

lib/share.ts

@@ -1,18 +1,22 @@
 /**
- * Short link client — talks to the BFF /share endpoints.
+ * Short link client.
  *
- * Used by the text-selection toolbar (`buildShortHighlightUrl`) and the
- * `/share/[code]` page (`resolveShortLink`).
+ * - `createShortLink` runs in the browser and POSTs to `/api/share`, a Next.js
+ *   route handler that proxies to the BFF. We can't call the BFF directly
+ *   from the browser because `BFF_URL` is not exposed to the client bundle
+ *   (no `NEXT_PUBLIC_` prefix). Same-origin proxy also avoids CORS.
+ *
+ * - `resolveShortLink` is only called from the `/share/[code]` server
+ *   component, so it can use `bff()` directly with the server-side env var.
  */
 
-import { bff, bffPost } from "@/lib/bff";
+import { bff } from "@/lib/bff";
 
 // Module-scoped cache: a single user shouldn't generate a fresh code every
 // time they re-click Share on the same selection. Keyed by the relative path
 // (including ?hl=…), this returns the same promise for repeat calls.
 const createCache = new Map<string, Promise<string | null>>();
 
-type CreateResponse = { code: string };
 type ResolveResponse = { url: string };
 
 /**
@@ -23,8 +27,20 @@ export function createShortLink(longPath: string): Promise<string | null> {
   const cached = createCache.get(longPath);
   if (cached) return cached;
 
-  const promise = bffPost<CreateResponse>("/share", { url: longPath })
-    .then((r) => r.code)
+  const promise = fetch("/api/share", {
+    method: "POST",
+    headers: {
+      "Content-Type": "application/json",
+      Accept: "application/json",
+    },
+    body: JSON.stringify({ url: longPath }),
+  })
+    .then(async (res) => {
+      if (!res.ok) return null;
+      const json = await res.json().catch(() => null);
+      const code = json?.data?.code;
+      return typeof code === "string" ? code : null;
+    })
     .catch(() => null);
 
   createCache.set(longPath, promise);