fix: improve CodingPage filter UX and prevent race conditions

- Show grand total count (data.total) instead of items.length
- Display active fallgruppe filter label prominently
- Add AbortController to cancel stale requests on rapid filter changes
- Clarify badge to show "X / Y auf dieser Seite codiert"

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/pages/CodingPage.tsx

@@ -59,11 +59,12 @@ export function CodingPage() {
 
   // Fetch coding queue
   useEffect(() => {
+    const controller = new AbortController()
     setLoading(true)
     const params: Record<string, string | number> = { page, per_page: 50 }
     if (fallgruppe !== '__all__') params.fallgruppe = fallgruppe
 
-    api.get<CaseListResponse>('/coding/queue', { params })
+    api.get<CaseListResponse>('/coding/queue', { params, signal: controller.signal })
       .then((res) => {
         setData(res.data)
         // Initialize form states for each case
@@ -75,8 +76,14 @@ export function CodingPage() {
         setSavedIds(new Set())
         setErrors({})
       })
-      .catch(() => setData(null))
+      .catch(() => {
-      .finally(() => setLoading(false))
+        if (!controller.signal.aborted) setData(null)
+      })
+      .finally(() => {
+        if (!controller.signal.aborted) setLoading(false)
+      })
+
+    return () => controller.abort()
   }, [page, fallgruppe])
 
   const updateFormField = (caseId: number, field: keyof CodingFormState, value: unknown) => {
@@ -124,19 +131,32 @@ export function CodingPage() {
     }
   }
 
-  // Count coded cases
+  // Count coded cases on current page
   const codedCount = data
     ? data.items.filter((c) => savedIds.has(c.id) || c.gutachten_typ !== null).length
     : 0
-  const totalCount = data?.items.length ?? 0
+  const grandTotal = data?.total ?? 0
+  const activeFilterLabel = fallgruppe !== '__all__'
+    ? FALLGRUPPEN_LABELS[fallgruppe] || fallgruppe
+    : null
 
   return (
     <div className="p-6 space-y-4">
       <div className="flex flex-wrap items-center justify-between gap-4">
+        <div>
           <h1 className="text-2xl font-bold">Coding-Warteschlange</h1>
+          {!loading && data && (
+            <p className="text-sm text-muted-foreground mt-0.5">
+              {grandTotal} {grandTotal === 1 ? 'Fall' : 'Fälle'} offen
+              {activeFilterLabel && (
+                <> — gefiltert nach <span className="font-medium text-foreground">{activeFilterLabel}</span></>
+              )}
+            </p>
+          )}
+        </div>
         <div className="flex items-center gap-3">
           <Badge variant="outline" className="text-sm py-1 px-3">
-            {codedCount} von {totalCount} Fälle codiert
+            {codedCount} / {data?.items.length ?? 0} auf dieser Seite codiert
           </Badge>
           <Select value={fallgruppe} onValueChange={(v) => { setFallgruppe(v); setPage(1) }}>
             <SelectTrigger className="w-[180px]">
@@ -152,11 +172,11 @@ export function CodingPage() {
       </div>
 
       {/* Progress bar */}
-      {data && totalCount > 0 && (
+      {data && grandTotal > 0 && (
         <div className="h-2 w-full rounded-full bg-muted overflow-hidden">
           <div
             className="h-full rounded-full bg-primary transition-all duration-300"
-            style={{ width: `${(codedCount / totalCount) * 100}%` }}
+            style={{ width: `${(codedCount / (data.items.length || 1)) * 100}%` }}
           />
         </div>
       )}