Harden AI writer response handling

src/vk_parser_app/workers/ai_writer.py

@@ -41,6 +41,7 @@ Rules:
 - Pick exactly one category from the categories list in input and return its numeric id as category_id.
 - Do not add links or hashtags to rewritten text.
 - Return JSON only. No markdown. No text outside JSON.
+- Never return an empty object. Never omit the "rewrites" key.
 - Return one rewrite for every input post id.
 - The "text" field must be a ready-to-publish Russian post with normal paragraph line breaks encoded as JSON string newlines.
 - The "notes" field must be a short editor note in Russian or null.
@@ -434,6 +435,8 @@ class AIWriterWorker:
             for p in posts
         }
         batch_id = await self.create_batch(provider, model, prompt, payload)
+        response = None
+        usage = None
         try:
             response, usage = await self.call_ai(provider, model, api_key, api_base, prompt, payload, temperature, timeout)
             rewrites = validate_rewrites(response, set(post_ids), categories, source_tags_by_id)
@@ -443,7 +446,7 @@ class AIWriterWorker:
             return True
         except Exception as exc:
             await self.mark_posts_failed(post_ids, str(exc))
-            await self.finish_batch(batch_id, "failed", error=str(exc))
+            await self.finish_batch(batch_id, "failed", response=response, error=str(exc), usage=usage)
             logger.exception("AI writer batch failed: id={} error={}", batch_id, exc)
             return True