fix: apply baseURL to production assets (#3734)

Author: pi0

src/build/plugins/public-assets.ts

@@ -6,7 +6,7 @@ import type { Nitro } from "nitro/types";
 import type { PublicAsset } from "nitro/types";
 import { relative, resolve } from "pathe";
 import type { Plugin } from "rollup";
-import { withTrailingSlash } from "ufo";
+import { joinURL, withTrailingSlash } from "ufo";
 import { virtual } from "./virtual.ts";
 
 const readAssetHandler: Record<
@@ -42,7 +42,10 @@ export function publicAssets(nitro: Nitro): Plugin {
           const etag = createEtag(assetData);
           const stat = await fsp.stat(fullPath);
 
-          const assetId = "/" + decodeURIComponent(id);
+          const assetId = joinURL(
+            nitro.options.baseURL,
+            decodeURIComponent(id)
+          );
 
           let encoding;
           if (id.endsWith(".gz")) {
@@ -114,7 +117,9 @@ export function readAsset (id) {
           nitro.options.publicAssets
             .filter((dir) => !dir.fallthrough && dir.baseURL !== "/")
             .map((dir) => [
-              withTrailingSlash(dir.baseURL),
+              withTrailingSlash(
+                joinURL(nitro.options.baseURL, dir.baseURL || "/")
+              ),
               { maxAge: dir.maxAge },
             ])
         );

src/presets/standard/preset.ts

@@ -5,6 +5,9 @@ const standard = defineNitroPreset(
     entry: "./standard/runtime/server",
     serveStatic: false,
     exportConditions: ["import", "default"],
+    output: {
+      publicDir: "{{ output.dir }}/public/{{ baseURL }}",
+    },
     commands: {
       preview: "npx srvx --prod ./",
     },