Add raw AI response to parse result for debugging

- Backend returns raw AI text alongside parsed fields
- Drawer shows expandable "Raw AI response" section when result has empty fields
- Scan Receipt shows raw response inline if no fields were extracted
- Helps diagnose model output issues without needing server logs

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

frontend/src/api/settings.ts

@@ -21,6 +21,7 @@ export interface ParsedReceipt {
   date: string | null;
   description: string | null;
   category: string | null;
+  raw: string | null;
 }
 
 export async function getAiSettings(): Promise<AiSettings> {

frontend/src/pages/transactions/TransactionDetailDrawer.tsx

@@ -260,7 +260,16 @@ export default function TransactionDetailDrawer({ transaction, accountName, cate
                           {parseResult.data.date        && <div className="flex justify-between"><span className="text-muted-foreground">Date</span><span className="font-medium">{parseResult.data.date}</span></div>}
                           {parseResult.data.description && <div className="flex justify-between gap-4"><span className="text-muted-foreground shrink-0">Description</span><span className="font-medium text-right">{parseResult.data.description}</span></div>}
                           {parseResult.data.category    && <div className="flex justify-between"><span className="text-muted-foreground">Category hint</span><span className="font-medium">{parseResult.data.category}</span></div>}
+                          {!parseResult.data.merchant && !parseResult.data.amount && !parseResult.data.description && (
+                            <div className="text-muted-foreground">No fields detected.</div>
+                          )}
                         </div>
+                        {parseResult.data.raw && (
+                          <details className="text-xs">
+                            <summary className="text-muted-foreground cursor-pointer hover:text-foreground">Raw AI response</summary>
+                            <pre className="mt-1.5 bg-background rounded p-2 text-xs overflow-x-auto whitespace-pre-wrap break-all border border-border">{parseResult.data.raw}</pre>
+                          </details>
+                        )}
                         <div className="flex gap-2 pt-1">
                           <button
                             onClick={() => applyMutation.mutate(parseResult.data)}

frontend/src/pages/transactions/TransactionList.tsx

@@ -104,8 +104,13 @@ export default function TransactionList() {
     setScanError(null);
     try {
       const parsed = await parseReceiptFile(file);
-      setReceiptParsed(parsed);
-      setShowForm(true);
+      const hasAnyField = parsed.merchant || parsed.amount || parsed.description || parsed.date;
+      if (!hasAnyField && parsed.raw) {
+        setScanError(`AI couldn't extract any fields. Raw response: "${parsed.raw}"`);
+      } else {
+        setReceiptParsed(parsed);
+        setShowForm(true);
+      }
     } catch (e: any) {
       setScanError(e?.response?.data?.detail ?? "Could not parse receipt. Check your AI settings.");
     } finally {