diff --git a/src/components/PreviewBlock.jsx b/src/components/PreviewBlock.jsx
index f3a7f9f..06498a2 100644
--- a/src/components/PreviewBlock.jsx
+++ b/src/components/PreviewBlock.jsx
@@ -1,5 +1,5 @@
 import { useState, useEffect, useCallback, useRef } from 'react'
-import { MODE_OPTIONS, previewStatus, modeHint } from '../lib/previewView'
+import { modeOptionsFor, previewStatus, modeHint, isDevUnavailableError, NO_DEV_HINT } from '../lib/previewView'
 import { isValidEnvName, buildEnvPayload, isDevPreview, dotColor, envValueTooLong, MAX_ENV_VARS } from '../lib/previewEnv'
 import {
   fetchPreview,
@@ -198,15 +198,16 @@ export default function PreviewBlock({ projectId }) {
               disabled={busy || inactive}
               onChange={(e) => run(() => setPreviewMode(projectId, e.target.value))}
             >
-              {MODE_OPTIONS.map((o) => <option key={o.value} value={o.value}>{o.label}</option>)}
+              {modeOptionsFor(data.devAvailable).map((o) => <option key={o.value} value={o.value} disabled={o.disabled}>{o.label}</option>)}
             </select>
           </div>
+          {data.devAvailable === false && <div className="text-grey" style={{ ...small, marginTop: 4 }}>{NO_DEV_HINT}</div>}
           {hint && <div className="text-grey" style={{ ...small, marginTop: 4 }}>{hint}</div>}
           <div style={{ marginTop: 8, display: 'flex', gap: 6, alignItems: 'flex-start' }}>
             <span style={{ width: 10, height: 10, borderRadius: '50%', background: dotColor(STATE_OF_COLOR[status.color]), display: 'inline-block', flexShrink: 0, marginTop: 4 }} />
             <span style={{ overflowWrap: 'anywhere' }}>{status.text}</span>
           </div>
-          {data.state === 'failed' && data.error && (
+          {data.state === 'failed' && data.error && !isDevUnavailableError(data.error) && (
             <div style={{ color: '#f87171', ...small, marginTop: 4, overflowWrap: 'anywhere' }}>{data.error}</div>
           )}
         </>
diff --git a/src/lib/previewView.js b/src/lib/previewView.js
index 13a25ed..8219d28 100644
--- a/src/lib/previewView.js
+++ b/src/lib/previewView.js
@@ -7,6 +7,18 @@ export const MODE_OPTIONS = [
   { value: 'off', label: 'Aus' },
 ]
 
+export const NO_DEV_HINT = 'Reines HTML braucht keinen Dev-Server – Änderungen erscheinen nach jedem Push automatisch.'
+const DEV_UNAVAILABLE = 'Dev-Modus hier nicht möglich'
+
+// Modus-Optionen; "Dev-Server" nur wählbar, wenn das Projekt ein dev-Skript hat (devAvailable !== false)
+export function modeOptionsFor(devAvailable) {
+  return MODE_OPTIONS.map((o) => (o.value === 'dev' && devAvailable === false
+    ? { ...o, label: 'Dev-Server (kein dev-Skript)', disabled: true }
+    : { ...o, disabled: false }))
+}
+
+export const isDevUnavailableError = (error) => typeof error === 'string' && error.startsWith(DEV_UNAVAILABLE)
+
 const dateFormat = new Intl.DateTimeFormat('de-DE', {
   timeZone: 'Europe/Berlin',
   day: '2-digit',
@@ -40,6 +52,7 @@ export function previewStatus(p) {
     case 'sleeping':
       return { color: 'yellow', text: 'Dev-Server schläft, startet beim nächsten Aufruf' }
     case 'failed':
+      if (isDevUnavailableError(p.error)) return { color: 'yellow', text: 'Dev-Modus hier nicht möglich – statische Version ist online' }
       return { color: 'red', text: 'Build fehlgeschlagen – letzte funktionierende Version ist online' }
     default:
       return { color: 'grey', text: 'Keine Preview' }
diff --git a/tests/unit/previewView.test.mjs b/tests/unit/previewView.test.mjs
index c6ede46..d586709 100644
--- a/tests/unit/previewView.test.mjs
+++ b/tests/unit/previewView.test.mjs
@@ -2,7 +2,7 @@ import test from 'node:test'
 import assert from 'node:assert/strict'
 import { loadModule } from './load.mjs'
 
-const { previewStatus, detectedLabel, modeHint, MODE_OPTIONS } = await loadModule('src/lib/previewView.js')
+const { previewStatus, detectedLabel, modeHint, MODE_OPTIONS, modeOptionsFor, isDevUnavailableError } = await loadModule('src/lib/previewView.js')
 
 test('previewStatus online: Datum in Europe/Berlin und sha7', () => {
   const s = previewStatus({ state: 'online', builtAt: '2026-09-30T13:05:00Z', builtSha: 'abcdef1234567890' })
@@ -61,3 +61,21 @@ test('MODE_OPTIONS', () => {
     { value: 'off', label: 'Aus' },
   ])
 })
+
+test('previewStatus failed + Dev-Modus nicht möglich => gelb, kein roter Build-Fehler', () => {
+  const s = previewStatus({ state: 'failed', error: 'Dev-Modus hier nicht möglich – statische Version ist online' })
+  assert.deepEqual(s, { color: 'yellow', text: 'Dev-Modus hier nicht möglich – statische Version ist online' })
+  assert.equal(previewStatus({ state: 'failed', error: 'Build kaputt' }).color, 'red')
+  assert.equal(isDevUnavailableError('Dev-Modus hier nicht möglich – x'), true)
+  assert.equal(isDevUnavailableError(''), false)
+})
+
+test('modeOptionsFor: dev nur bei devAvailable === false gesperrt', () => {
+  for (const a of [true, null, undefined]) {
+    assert.ok(modeOptionsFor(a).every((o) => !o.disabled))
+    assert.equal(modeOptionsFor(a).find((o) => o.value === 'dev').label, 'Dev-Server')
+  }
+  const o = modeOptionsFor(false)
+  assert.deepEqual(o.find((x) => x.value === 'dev'), { value: 'dev', label: 'Dev-Server (kein dev-Skript)', disabled: true })
+  assert.equal(o.filter((x) => x.disabled).length, 1)
+})