update

backend/config.py

@@ -266,7 +266,10 @@ FORMAT_PURPOSE = {
 #        "judge" = mapping/judge/check agents — cold (low temperature,
 #                  no thinking) for stable verdicts; Claude/local map to "fast",
 #        "guide" = large generation (proposals, writer).
-DEFAULT_PROVIDER = "claude"
+# Kein Provider-Default im Code (Betreiber-Vorgabe): die .env entscheidet.
+DEFAULT_PROVIDER = os.getenv("DEFAULT_PROVIDER", "")
+if not DEFAULT_PROVIDER:
+    raise RuntimeError("DEFAULT_PROVIDER fehlt in der .env (z. B. DEFAULT_PROVIDER=minimax)")
 PROVIDERS = {
     "claude": {
         "cli": "claude",