fix: strip markdown code fences from LLM JSON responses

Claude wraps JSON in ```json ... ``` fences even when instructed to
return raw JSON. This caused all TopicResult validations to fail with
"Invalid JSON at line 1 column 1". Strip fences before parsing.

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

.vps-lab-config.json

@@ -8,13 +8,21 @@
     "clone_url": "https://git.mlhub.it/Michele/postgenerator.git"
   },
   "vps": {
-    "deployed": false,
-    "url": null,
+    "deployed": true,
+    "url": "https://lab.mlhub.it/postgenerator/",
+    "last_deploy": "2026-03-09T11:06:00Z",
     "container": "lab-postgenerator-app",
     "path": "/opt/lab-postgenerator/"
   },
   "supabase": {
     "enabled": false,
     "project_ref": null
+  },
+  "resources": {
+    "limits": {
+      "ram_mb": 1024,
+      "cpu_percent": 100
+    },
+    "deployed_at": "2026-03-09T11:06:00Z"
   }
 }

backend/services/llm_service.py

@@ -12,6 +12,7 @@ from __future__ import annotations
 import json
 import logging
 import random
+import re
 import time
 from typing import Type, TypeVar
 
@@ -111,9 +112,10 @@ class LLMService:
                     elapsed,
                 )
 
-                # Valida con Pydantic
+                # Rimuovi eventuali code fences markdown e valida con Pydantic
+                clean_text = self._strip_code_fences(raw_text)
                 try:
-                    result = response_schema.model_validate_json(raw_text)
+                    result = response_schema.model_validate_json(clean_text)
                     # Pausa inter-request dopo chiamata riuscita
                     time.sleep(self._inter_request_delay)
                     return result
@@ -259,6 +261,20 @@ class LLMService:
     # Metodi privati
     # ---------------------------------------------------------------------------
 
+    @staticmethod
+    def _strip_code_fences(text: str) -> str:
+        """Rimuove i code fences markdown dalla risposta LLM.
+
+        Claude a volte wrappa il JSON in ```json ... ``` anche quando
+        gli si chiede di rispondere solo con JSON.
+        """
+        stripped = text.strip()
+        # Rimuove ```json ... ``` o ``` ... ```
+        match = re.match(r"^```(?:json)?\s*\n?(.*?)\n?\s*```$", stripped, re.DOTALL)
+        if match:
+            return match.group(1).strip()
+        return stripped
+
     @staticmethod
     def _parse_retry_after(error: anthropic.RateLimitError) -> float:
         """Estrae il valore retry-after dall'eccezione RateLimitError.

frontend/src/api/hooks.ts

@@ -37,7 +37,7 @@ import type {
 export function useSettings() {
   return useQuery<Settings>({
     queryKey: ['settings'],
-    queryFn: () => apiGet<Settings>('/settings'),
+    queryFn: () => apiGet<Settings>('/settings/'),
     staleTime: 60_000,
   })
 }
@@ -56,7 +56,7 @@ export function useSettingsStatus() {
 export function useUpdateSettings() {
   const queryClient = useQueryClient()
   return useMutation<Settings, Error, Partial<Settings>>({
-    mutationFn: (settings) => apiPut<Settings>('/settings', settings),
+    mutationFn: (settings) => apiPut<Settings>('/settings/', settings),
     onSuccess: () => {
       queryClient.invalidateQueries({ queryKey: ['settings'] })
     },
@@ -199,7 +199,7 @@ export function useDownloadEditedCsv() {
 export function usePromptList() {
   return useQuery<PromptListResponse>({
     queryKey: ['prompts'],
-    queryFn: () => apiGet<PromptListResponse>('/prompts'),
+    queryFn: () => apiGet<PromptListResponse>('/prompts/'),
     staleTime: 30_000,
   })
 }