feat(ai): reichhaltigeres Logging fuer AI_FAILED-Diagnose

Der bisherige Log "[extract-from-photo] AI_FAILED after 43165ms,
385807 bytes" verriet nicht, ob es JSON-Parse, Schema-Validierung
oder ein SDK-Fehler war. Endpoint haengt jetzt e.message an;
gemini-client loggt den First-Attempt-Fehler vor dem Retry und
packt bei AI_FAILED beide Messages in den finalen Error.

Keine Prompt-/Response-Inhalte werden geloggt -- nur unsere eigenen
GeminiError-Messages (Zod-Pfade, "non-JSON output", SDK-toString).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/server/ai/gemini-client.ts

@@ -114,6 +114,7 @@ export async function extractRecipeFromImage(
   imageBuffer: Buffer,
   mimeType: string
 ): Promise<ExtractionResponse> {
+  let firstMsg: string | null = null;
   try {
     return await callGemini(imageBuffer, mimeType);
   } catch (e) {
@@ -132,6 +133,9 @@ export async function extractRecipeFromImage(
         : new GeminiError('AI_FAILED', String(e));
     }
 
+    firstMsg = e instanceof Error ? e.message : String(e);
+    console.warn(`[gemini-client] first attempt failed, retrying: ${firstMsg}`);
+
     await new Promise((r) => setTimeout(r, 500));
     try {
       return await callGemini(
@@ -140,11 +144,23 @@ export async function extractRecipeFromImage(
         'Dein vorheriger Output war ungültig. Bitte antworte ausschließlich mit JSON gemäß Schema.'
       );
     } catch (retryErr) {
-      if (retryErr instanceof GeminiError) throw retryErr;
+      const retryMsg = retryErr instanceof Error ? retryErr.message : String(retryErr);
+      if (retryErr instanceof GeminiError) {
+        if (retryErr.code === 'AI_FAILED') {
+          throw new GeminiError(
+            'AI_FAILED',
+            `retry failed: ${retryMsg} (first: ${firstMsg})`
+          );
+        }
+        throw retryErr;
+      }
       const retryStatus = getStatus(retryErr);
       if (retryStatus === 429)
         throw new GeminiError('AI_RATE_LIMITED', 'Gemini rate limit on retry');
-      throw new GeminiError('AI_FAILED', String(retryErr));
+      throw new GeminiError(
+        'AI_FAILED',
+        `retry failed: ${retryMsg} (first: ${firstMsg})`
+      );
     }
   }
 }

src/routes/api/recipes/extract-from-photo/+server.ts

@@ -121,9 +121,11 @@ export const POST: RequestHandler = async ({ request, getClientAddress }) => {
             : e.code === 'AI_NOT_CONFIGURED'
               ? 503
               : 503;
-      // Nur Code + Meta loggen, niemals Prompt/Response-Inhalt.
+      // Nur Code + Meta + Error-Message loggen, niemals Prompt/Response-Inhalt.
+      // e.message enthaelt z.B. Zod-Validierungspfade oder "non-JSON output" --
+      // kein AI-Content, aber die Diagnose-Info, warum AI_FAILED kam.
       console.warn(
-        `[extract-from-photo] ${e.code} after ${Date.now() - startedAt}ms, ${preprocessed.buffer.byteLength} bytes`
+        `[extract-from-photo] ${e.code} after ${Date.now() - startedAt}ms, ${preprocessed.buffer.byteLength} bytes: ${e.message}`
       );
       return errJson(status, e.code, 'Die Bild-Analyse ist fehlgeschlagen.');
     }