diff --git a/src/node/build/build.ts b/src/node/build/build.ts
index 0b1da0c2d..3bce78bd9 100644
--- a/src/node/build/build.ts
+++ b/src/node/build/build.ts
@@ -65,39 +65,42 @@ export async function build(
     const { render } = await nativeImport(entryPath)
 
     await task('rendering pages', async () => {
-      const appChunk =
-        clientResult &&
-        (clientResult.output.find(
-          (chunk) =>
-            chunk.type === 'chunk' &&
-            chunk.isEntry &&
-            chunk.facadeModuleId?.endsWith('.js')
-        ) as Rolldown.OutputChunk)
-
-      const cssChunk = (
-        siteConfig.mpa ? serverResult : clientResult!
-      ).output.find(
-        (chunk) => chunk.type === 'asset' && chunk.fileName.endsWith('.css')
-      ) as Rolldown.OutputAsset
-
-      const assets = (siteConfig.mpa ? serverResult : clientResult!).output
-        .filter(
-          (chunk) => chunk.type === 'asset' && !chunk.fileName.endsWith('.css')
-        )
-        .map((asset) => siteConfig.site.base + asset.fileName)
+      const clientOutput: (Rolldown.OutputChunk | Rolldown.OutputAsset)[] =
+        clientResult?.output || []
+
+      const appChunk = clientOutput.find(
+        (chunk): chunk is Rolldown.OutputChunk =>
+          chunk.type === 'chunk' &&
+          chunk.isEntry &&
+          !!chunk.facadeModuleId?.endsWith('.js')
+      )
 
-      // default theme special handling: inject font preload
-      // custom themes will need to use `transformHead` to inject this
-      const additionalHeadTags: HeadConfig[] = []
-      const isDefaultTheme =
-        clientResult &&
-        clientResult.output.some(
-          (chunk) =>
-            chunk.type === 'chunk' &&
-            chunk.name === 'theme' &&
-            chunk.moduleIds.some((id) => id.includes('client/theme-default'))
-        )
+      const isDefaultTheme = clientOutput.some(
+        (chunk): chunk is Rolldown.OutputChunk =>
+          chunk.type === 'chunk' &&
+          chunk.name === 'theme' &&
+          chunk.moduleIds.some((id) => id.includes('client/theme-default'))
+      )
+
+      // ----
 
+      const resultOutput: (Rolldown.OutputChunk | Rolldown.OutputAsset)[] =
+        (siteConfig.mpa ? serverResult : clientResult)?.output || []
+
+      const cssChunk = resultOutput.find(
+        (chunk): chunk is Rolldown.OutputAsset =>
+          chunk.type === 'asset' && chunk.fileName.endsWith('.css')
+      )
+
+      // prettier-ignore
+      const assets = resultOutput.filter(
+        (chunk): chunk is Rolldown.OutputAsset =>
+          chunk.type === 'asset' && !chunk.fileName.endsWith('.css')
+      ).map((asset) => siteConfig.site.base + asset.fileName)
+
+      // ----
+
+      const additionalHeadTags: HeadConfig[] = []
       const metadataScript = generateMetadataScript(pageToHashMap, siteConfig)
 
       if (isDefaultTheme) {
diff --git a/src/node/build/bundle.ts b/src/node/build/bundle.ts
index ad25459b7..f851b3d58 100644
--- a/src/node/build/bundle.ts
+++ b/src/node/build/bundle.ts
@@ -2,6 +2,7 @@ import fs from 'node:fs'
 import { cp } from 'node:fs/promises'
 import path from 'node:path'
 import { fileURLToPath } from 'node:url'
+import pMap from 'p-map'
 import {
   build,
   normalizePath,
@@ -102,8 +103,8 @@ export async function bundle(
           app: path.resolve(APP_PATH, ssr ? 'ssr.js' : 'index.js'),
           ...input
         },
-        // important so that each page chunk and the index export things for each
-        // other
+        // important so that each page chunk and the index export things for
+        // each other
         preserveEntrySignatures: 'allow-extension',
         output: {
           sanitizeFileName,
@@ -170,42 +171,40 @@ export async function bundle(
     configFile: config.vite?.configFile
   })
 
-  let clientResult!: Rolldown.RolldownOutput | null
+  let clientResult: Rolldown.RolldownOutput | null = null
   let serverResult!: Rolldown.RolldownOutput
 
+  // prettier-ignore
   await task('building client + server bundles', async () => {
-    clientResult = config.mpa
-      ? null
-      : ((await build(
-          await resolveViteConfig(false)
-        )) as Rolldown.RolldownOutput)
-    serverResult = (await build(
-      await resolveViteConfig(true)
-    )) as Rolldown.RolldownOutput
+    if (!config.mpa) clientResult =
+      (await build(await resolveViteConfig(false))) as Rolldown.RolldownOutput
+    serverResult =
+      (await build(await resolveViteConfig(true))) as Rolldown.RolldownOutput
   })
 
   if (config.mpa) {
     // in MPA mode, we need to copy over the non-js asset files from the
     // server build since there is no client-side build.
-    await Promise.all(
-      serverResult.output.map(async (chunk) => {
+    await pMap(
+      serverResult.output,
+      async (chunk) => {
         if (!chunk.fileName.endsWith('.js')) {
           const tempPath = path.resolve(config.tempDir, chunk.fileName)
           const outPath = path.resolve(config.outDir, chunk.fileName)
           await cp(tempPath, outPath)
         }
-      })
+      },
+      { concurrency: config.buildConcurrency }
     )
+
     // also copy over public dir
     const publicDir = path.resolve(config.srcDir, 'public')
     if (fs.existsSync(publicDir)) {
       // dereference symlinks like vite's own publicDir copy does, and so that
       // copying over an existing symlinked file does not fail with EEXIST
-      await cp(publicDir, config.outDir, {
-        recursive: true,
-        dereference: true
-      })
+      await cp(publicDir, config.outDir, { recursive: true, dereference: true })
     }
+
     // build <script client> bundle
     if (Object.keys(clientJSMap).length) {
       clientResult = await buildMPAClient(clientJSMap, config)
diff --git a/src/node/build/render.ts b/src/node/build/render.ts
index 570418ffe..b09821f8b 100644
--- a/src/node/build/render.ts
+++ b/src/node/build/render.ts
@@ -24,9 +24,9 @@ export async function renderPage(
   render: (path: string) => Promise<SSGContext>,
   config: SiteConfig,
   page: string, // foo.md
-  result: Rolldown.RolldownOutput | null,
-  appChunk: Rolldown.OutputChunk | null,
-  cssChunk: Rolldown.OutputAsset | null,
+  result: Rolldown.RolldownOutput | null | undefined,
+  appChunk: Rolldown.OutputChunk | null | undefined,
+  cssChunk: Rolldown.OutputAsset | null | undefined,
   assets: string[],
   pageToHashMap: Record<string, string>,
   metadataScript: { html: string; inHead: boolean },
@@ -140,10 +140,10 @@ export async function renderPage(
   let inlinedScript = ''
   if (config.mpa && result) {
     const matchingChunk = result.output.find(
-      (chunk) =>
+      (chunk): chunk is Rolldown.OutputChunk =>
         chunk.type === 'chunk' &&
         chunk.facadeModuleId === slash(path.join(config.srcDir, page))
-    ) as Rolldown.OutputChunk
+    )
     if (matchingChunk) {
       if (!matchingChunk.code.includes('import')) {
         inlinedScript = `<script type="module">${matchingChunk.code}</script>`
@@ -227,12 +227,13 @@ function resolvePageImports(
   }
   srcPath = normalizePath(srcPath)
   const pageChunk = result.output.find(
-    (chunk) => chunk.type === 'chunk' && chunk.facadeModuleId === srcPath
-  ) as Rolldown.OutputChunk
+    (chunk): chunk is Rolldown.OutputChunk =>
+      chunk.type === 'chunk' && chunk.facadeModuleId === srcPath
+  )
   return [
     ...appChunk.imports,
     // ...appChunk.dynamicImports,
-    ...pageChunk.imports
+    ...(pageChunk?.imports || [])
     // ...pageChunk.dynamicImports
   ]
 }
diff --git a/src/node/plugin.ts b/src/node/plugin.ts
index 09bc3e88f..e415bde67 100644
--- a/src/node/plugin.ts
+++ b/src/node/plugin.ts
@@ -53,14 +53,13 @@ const staticRestoreRE = /__VP_STATIC_(START|END)__/g
 // media queries.
 const scriptClientRE = /<script\b[^>]*client\b[^>]*>([^]*?)<\/script>/
 
-const isPageChunk = (
-  chunk: Rolldown.OutputAsset | Rolldown.OutputChunk
-): chunk is Rolldown.OutputChunk & { facadeModuleId: string } =>
+const isPageChunk = <T extends Rolldown.OutputChunk | Rolldown.RenderedChunk>(
+  chunk: Rolldown.OutputAsset | T
+): chunk is T =>
   !!(
     chunk.type === 'chunk' &&
     chunk.isEntry &&
-    chunk.facadeModuleId &&
-    chunk.facadeModuleId.endsWith('.md')
+    chunk.facadeModuleId?.endsWith('.md')
   )
 
 const cleanUrl = (url: string): string => url.replace(/[?#].*$/s, '')
@@ -285,7 +284,7 @@ export async function createVitePressPlugin(
     },
 
     renderChunk(code, chunk) {
-      if (!ssr && isPageChunk(chunk as Rolldown.OutputChunk)) {
+      if (!ssr && isPageChunk(chunk)) {
         // For each page chunk, inject marker for start/end of static strings.
         // we do this here because in generateBundle the chunks would have been
         // minified and we won't be able to safely locate the strings.