Add error details to APIError messages.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

core/anthropic/errors.py

@@ -46,9 +46,10 @@ def get_user_facing_error_message(
     if name == "OverloadedError":
         return "Provider is currently overloaded. Please retry."
     if name == "APIError":
+        raw = str(e)
         if status_code in (502, 503, 504):
             return "Provider is temporarily unavailable. Please retry."
-        return "Provider API request failed."
+        return f"Provider API request failed. Details: {raw[:150]}"
     if name.endswith("ProviderError") or name == "ProviderError":
         return "Provider request failed."