Env robustness: context-safe prompting + tool arg normalization

- Preserve full trajectory while truncating prompt view per turn (avoids context overflow)
- Add max_context_tokens support and wire from env config
- Normalize tool call arguments robustly (dict / stringified JSON / plain string)
- Avoid double-encoding tool arguments in Hermes parser
- Add tool-call metrics to AgentResult for debugging/optional shaping

Scope: environments/* only

environments/tool_call_parsers/hermes_parser.py

@@ -49,15 +49,22 @@ class HermesToolCallParser(ToolCallParser):
                     continue
 
                 tc_data = json.loads(raw_json)
+                # Handle arguments: could be dict or already a JSON string
+                raw_args = tc_data.get("arguments", {})
+                if isinstance(raw_args, str):
+                    # Already a string — pass through as-is.
+                    # It may be a JSON string ("{...}") or a plain string ("ls").
+                    args_str = raw_args
+                else:
+                    # Dict — serialize to JSON
+                    args_str = json.dumps(raw_args, ensure_ascii=False)
                 tool_calls.append(
                     ChatCompletionMessageToolCall(
                         id=f"call_{uuid.uuid4().hex[:8]}",
                         type="function",
                         function=Function(
                             name=tc_data["name"],
-                            arguments=json.dumps(
-                                tc_data.get("arguments", {}), ensure_ascii=False
-                            ),
+                            arguments=args_str,
                         ),
                     )
                 )