diff --git a/frontend/src/tools/kalkulator3d.jsx b/frontend/src/tools/kalkulator3d.jsx
index ef38c6d..03b7544 100644
--- a/frontend/src/tools/kalkulator3d.jsx
+++ b/frontend/src/tools/kalkulator3d.jsx
@@ -48,8 +48,14 @@ function compressImage(file) {
 
 // ── Stepper ───────────────────────────────────────────────────────────────────
 function Stepper({ label, value, onChange, step, unit, min = 0, hint }) {
-  const dec = () => onChange(Math.max(min, Math.round((value - step) * 10000) / 10000));
-  const inc = () => onChange(Math.round((value + step) * 10000) / 10000);
+  const [raw, setRaw] = useState(String(value));
+
+  // Sync wenn value sich von außen ändert (z.B. beim Bearbeiten eines Archiv-Eintrags)
+  useEffect(() => { setRaw(String(value)); }, [value]);
+
+  const dec = () => { const v = Math.max(min, Math.round((value - step) * 10000) / 10000); onChange(v); setRaw(String(v)); };
+  const inc = () => { const v = Math.round((value + step) * 10000) / 10000; onChange(v); setRaw(String(v)); };
+
   return (
     <div>
       <div style={{ color:'rgba(255,255,255,0.4)', fontSize:10, fontFamily:'monospace', marginBottom:5, letterSpacing:1 }}>
@@ -57,8 +63,18 @@ function Stepper({ label, value, onChange, step, unit, min = 0, hint }) {
       </div>
       <div style={{ display:'flex', alignItems:'center', background:'rgba(255,255,255,0.05)', borderRadius:8, border:'1px solid rgba(255,255,255,0.1)', overflow:'hidden' }}>
         <button onClick={dec} style={{ padding:'10px 12px', background:'transparent', border:'none', color:'rgba(255,255,255,0.6)', fontSize:20, cursor:'pointer', flexShrink:0, lineHeight:1 }}>−</button>
-        <input type="number" value={value} step={step}
-          onChange={e => onChange(parseFloat(e.target.value) || 0)}
+        <input
+          type="number" value={raw} step={step}
+          onChange={e => {
+            setRaw(e.target.value);
+            const parsed = parseFloat(e.target.value);
+            if (!isNaN(parsed)) onChange(Math.max(min, parsed));
+          }}
+          onBlur={() => {
+            const parsed = parseFloat(raw);
+            const safe = isNaN(parsed) ? min : Math.max(min, parsed);
+            onChange(safe); setRaw(String(safe));
+          }}
           style={{ flex:1, background:'transparent', border:'none', color:'#fff', fontSize:15, fontFamily:"'Space Mono',monospace", textAlign:'center', outline:'none', minWidth:0, padding:'10px 4px' }}
         />
         <button onClick={inc} style={{ padding:'10px 12px', background:'transparent', border:'none', color:'rgba(255,255,255,0.6)', fontSize:20, cursor:'pointer', flexShrink:0, lineHeight:1 }}>+</button>
@@ -69,11 +85,23 @@ function Stepper({ label, value, onChange, step, unit, min = 0, hint }) {
 }
 
 function SmallInput({ label, value, onChange, step = 0.01 }) {
+  const [raw, setRaw] = useState(String(value));
+  useEffect(() => { setRaw(String(value)); }, [value]);
   return (
     <div>
       <div style={{ color:'rgba(255,255,255,0.6)', fontSize:9, fontFamily:'monospace', marginBottom:3 }}>{label}</div>
-      <input type="number" value={value} step={step}
-        onChange={e => onChange(parseFloat(e.target.value) || 0)}
+      <input
+        type="number" value={raw} step={step}
+        onChange={e => {
+          setRaw(e.target.value);
+          const parsed = parseFloat(e.target.value);
+          if (!isNaN(parsed)) onChange(parsed);
+        }}
+        onBlur={() => {
+          const parsed = parseFloat(raw);
+          if (!isNaN(parsed)) { onChange(parsed); setRaw(String(parsed)); }
+          else setRaw(String(value));
+        }}
         style={{ ...S.inp, padding:'7px 8px', fontSize:13 }}
       />
     </div>
@@ -125,10 +153,12 @@ export default function Kalkulator3D({ toast, editData, onEditDone, mobile }) {
   const handleImagePick = async e => {
     const file = e.target.files?.[0];
     if (!file) return;
+    if (!file.type.startsWith('image/')) { toast('Nur Bilddateien erlaubt (JPG, PNG, …)', 'error'); e.target.value = ''; return; }
+    if (file.size > 20 * 1024 * 1024) { toast(`Bild zu groß (${(file.size/1024/1024).toFixed(1)} MB) – max. 20 MB`, 'error'); e.target.value = ''; return; }
     try {
       const compressed = await compressImage(file);
       setImage(compressed);
-    } catch { toast('Bild konnte nicht geladen werden', 'error'); }
+    } catch { toast('Bild konnte nicht verarbeitet werden – ist die Datei beschädigt?', 'error'); }
     e.target.value = '';
   };