Tolerate malformed LLM JSON escapes

packages/summarizer/summarizer.ts

@@ -372,6 +372,28 @@ function extractJsonObject(text: string): string {
   return trimmed;
 }
 
+function escapeInvalidJsonBackslashes(text: string): string {
+  return text.replace(/\\(?:u(?![0-9a-fA-F]{4})|(?!["\\/bfnrtu]))/g, "\\\\");
+}
+
+function parseLlmJson<T>(content: string, context: string): T {
+  const json = extractJsonObject(content);
+  try {
+    return JSON.parse(json) as T;
+  } catch (error) {
+    const repaired = escapeInvalidJsonBackslashes(json);
+    if (repaired !== json) {
+      try {
+        return JSON.parse(repaired) as T;
+      } catch {
+        // Fall through to the contextual error below.
+      }
+    }
+    const message = error instanceof Error ? error.message : String(error);
+    throw new SyntaxError(`${context}: ${message}`);
+  }
+}
+
 function summarizeSegmentierungsQualitaet(fragen: FrageMitAntwort[] | undefined): SegmentierungsQualitaet | undefined {
   const items = fragen ?? [];
   if (!items.length) return undefined;
@@ -961,9 +983,9 @@ ${JSON.stringify(data, null, 2)}`,
     );
   }
 
-  const parsed = JSON.parse(extractJsonObject(content)) as Partial<LlmScoringAssessment> & {
+  const parsed = parseLlmJson<Partial<LlmScoringAssessment> & {
     begruendung?: string;
-  };
+  }>(content, "Could not parse traffic light assessment JSON");
   const ausschlussgruende = Array.isArray(parsed.ausschlussgruende)
     ? parsed.ausschlussgruende.map((flag) => String(flag).trim()).filter(Boolean)
     : [];
@@ -1065,7 +1087,10 @@ Vorgaben:
     );
   }
 
-  const parsed = JSON.parse(extractJsonObject(content)) as { fragen?: Array<Partial<FrageMitAntwort>> };
+  const parsed = parseLlmJson<{ fragen?: Array<Partial<FrageMitAntwort>> }>(
+    content,
+    `Could not parse answer segmentation JSON for ${fallbackLabel}`,
+  );
   const byId = new Map((parsed.fragen ?? []).map((frage) => [String(frage.id ?? ""), frage]));
 
   return fragen.map((frage) => {
@@ -1149,7 +1174,7 @@ ${JSON.stringify(data, null, 2)}`,
     );
   }
 
-  const parsed = JSON.parse(extractJsonObject(content)) as Partial<SWOTAnalyse>;
+  const parsed = parseLlmJson<Partial<SWOTAnalyse>>(content, "Could not parse SWOT analysis JSON");
   const toStringArray = (value: unknown): string[] =>
     Array.isArray(value) ? value.map((item) => String(item).trim()).filter(Boolean) : [];