fix(middleware): handle string-serialized options in ClarificationMiddleware (#1997)

* fix(middleware): handle string-serialized options in ClarificationMiddleware (#1995)

Some models (e.g. Qwen3-Max) serialize array tool parameters as JSON
strings instead of native arrays. Add defensive type checking in
_format_clarification_message() to deserialize string options before
iteration, preventing per-character rendering.

* fix(middleware): normalize options after JSON deserialization

Address Copilot review feedback:
- Add post-deserialization normalization so options is always a list
  (handles json.loads returning a scalar string, dict, or None)
- Add test for JSON-encoded scalar string ("development")
- Fix test_json_string_with_mixed_types to use actual mixed types

backend/packages/harness/deerflow/agents/middlewares/clarification_middleware.py

@@ -1,5 +1,6 @@
 """Middleware for intercepting clarification requests and presenting them to the user."""
 
+import json
 import logging
 from collections.abc import Callable
 from typing import override
@@ -60,6 +61,20 @@ class ClarificationMiddleware(AgentMiddleware[ClarificationMiddlewareState]):
         context = args.get("context")
         options = args.get("options", [])
 
+        # Some models (e.g. Qwen3-Max) serialize array parameters as JSON strings
+        # instead of native arrays. Deserialize and normalize so `options`
+        # is always a list for the rendering logic below.
+        if isinstance(options, str):
+            try:
+                options = json.loads(options)
+            except (json.JSONDecodeError, TypeError):
+                options = [options]
+
+        if options is None:
+            options = []
+        elif not isinstance(options, list):
+            options = [options]
+
         # Type-specific icons
         type_icons = {
             "missing_info": "❓",