diff --git a/.env.example b/.env.example
index 5c5d5264..ff460c59 100644
--- a/.env.example
+++ b/.env.example
@@ -17,6 +17,14 @@ DEPLOYMENT_MODE="local"
 # Optional build-time release identifier. Use the same value for every replica
 # in one rollout; when omitted, each build generates a unique identifier.
 NEXT_DEPLOYMENT_ID=""
+# Optional build-time override of the Next.js output mode ("standalone" or
+# "export"). Unset defaults to the standard output on Vercel (its build
+# adapter cannot consume standalone output) and "standalone" elsewhere.
+NEXT_OUTPUT_MODE=""
+# Auto-injected by Vercel during its builds; do not set manually. It switches
+# the Next.js output mode away from standalone because Vercel's build adapter
+# cannot consume standalone output.
+VERCEL=""
 ALLOW_INSECURE_LOCAL_PRODUCTION="false"
 # Retained to opt deployment-gated media/image proxy surfaces into HTTP.
 ALLOW_LOCAL_NETWORK_PROXY=""
diff --git a/docs/environment-variables.md b/docs/environment-variables.md
index 2a3a0ff0..cc94b4ed 100644
--- a/docs/environment-variables.md
+++ b/docs/environment-variables.md
@@ -52,13 +52,14 @@ corepack pnpm byok:generate
 
 ## Deployment safety
 
-| Variable                          | Purpose                                                                                                                                                                                     |
-| --------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
-| `DEPLOYMENT_MODE`                 | Selects local or hosted deployment safeguards and shared-store expectations. It does not block user-configured HTTP or private-network targets.                                             |
-| `NEXT_DEPLOYMENT_ID`              | Optional build-time release ID shared by every replica in one rollout; drives Next.js version-skew protection and PWA cache rotation.                                                       |
-| `ALLOW_INSECURE_LOCAL_PRODUCTION` | Explicitly allows production `local` mode without `ACCESS_PASSWORD`. Use only for private deployments that are not exposed to the internet.                                                 |
-| `ALLOW_LOCAL_NETWORK_PROXY`       | Allows HTTP on deployment-gated media/image proxy surfaces. Private addresses themselves are no longer blocked; provider, search, RAG, plugin, and MCP policies do not depend on this flag. |
-| `TRUST_PROXY_HEADERS`             | Trust forwarded proxy headers only when the hosting platform strips spoofed values.                                                                                                         |
+| Variable                          | Purpose                                                                                                                                                                                                                                        |
+| --------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| `DEPLOYMENT_MODE`                 | Selects local or hosted deployment safeguards and shared-store expectations. It does not block user-configured HTTP or private-network targets.                                                                                                |
+| `NEXT_DEPLOYMENT_ID`              | Optional build-time release ID shared by every replica in one rollout; drives Next.js version-skew protection and PWA cache rotation.                                                                                                          |
+| `NEXT_OUTPUT_MODE`                | Optional build-time override of the Next.js output mode (`standalone` or `export`). Unset defaults to the standard output on Vercel, whose build adapter cannot consume standalone builds, and `standalone` for Docker and self-hosted builds. |
+| `ALLOW_INSECURE_LOCAL_PRODUCTION` | Explicitly allows production `local` mode without `ACCESS_PASSWORD`. Use only for private deployments that are not exposed to the internet.                                                                                                    |
+| `ALLOW_LOCAL_NETWORK_PROXY`       | Allows HTTP on deployment-gated media/image proxy surfaces. Private addresses themselves are no longer blocked; provider, search, RAG, plugin, and MCP policies do not depend on this flag.                                                    |
+| `TRUST_PROXY_HEADERS`             | Trust forwarded proxy headers only when the hosting platform strips spoofed values.                                                                                                                                                            |
 
 `TRUST_PROXY_HEADERS` affects request identity used by deployment diagnostics
 and rate limiting. Leave it `false` unless Neo Chat is behind a trusted proxy
diff --git a/next.config.ts b/next.config.ts
index 2eca848f..06164b70 100644
--- a/next.config.ts
+++ b/next.config.ts
@@ -48,6 +48,19 @@ function getDeploymentId(phase: string): string {
   return resolveDeploymentId(process.env, fallbackDeploymentId);
 }
 
+function resolveOutputMode(): NextConfig["output"] {
+  // Vercel's build adapter expects .next/next-server.js.nft.json, which
+  // standalone builds do not emit; Vercel packages functions itself, so it
+  // keeps the default output while Docker and self-hosted builds use
+  // standalone. NEXT_OUTPUT_MODE overrides the platform default explicitly.
+  const override = process.env.NEXT_OUTPUT_MODE?.trim();
+  if (override && override !== "standalone" && override !== "export") {
+    console.warn(`Ignoring unsupported NEXT_OUTPUT_MODE: "${override}"`);
+  }
+  if (override === "standalone" || override === "export") return override;
+  return process.env.VERCEL ? undefined : "standalone";
+}
+
 function createNextConfig(phase: string): NextConfig {
   const deploymentId = getDeploymentId(phase);
   const isE2EServer =
@@ -55,7 +68,7 @@ function createNextConfig(phase: string): NextConfig {
 
   return {
     /* config options here */
-    output: "standalone",
+    output: resolveOutputMode(),
     ...(isE2EServer && {
       distDir: ".next-e2e",
       typescript: { tsconfigPath: "tsconfig.e2e.json" },
diff --git a/src/__tests__/envExample.test.ts b/src/__tests__/envExample.test.ts
index a6913e4c..53dc89bc 100644
--- a/src/__tests__/envExample.test.ts
+++ b/src/__tests__/envExample.test.ts
@@ -9,6 +9,8 @@ const REQUIRED_ENV_KEYS = [
   "BYOK_ALLOW_EPHEMERAL_KEY",
   "DEPLOYMENT_MODE",
   "NEXT_DEPLOYMENT_ID",
+  "NEXT_OUTPUT_MODE",
+  "VERCEL",
   "ALLOW_INSECURE_LOCAL_PRODUCTION",
   "ALLOW_LOCAL_NETWORK_PROXY",
   "TRUST_PROXY_HEADERS",