fix: 角色agent轮数15→30 + read_file截断8000→30000（减少分段读浪费）

pipeline_service/agent_loop.py

@@ -543,7 +543,7 @@ async def _exec_agent_tool(tool, params, workspace_dir):
             if not _is_safe_workdir(full): return 'FAIL: 路径不在允许范围'
             if not os.path.isfile(full): return f'FAIL: 文件不存在 {path}'
             with open(full, encoding='utf-8') as f:
-                return f.read()[:8000]
+                return f.read()[:30000]
         elif tool == 'write_file':
             path = p.get('path', '')
             content = p.get('content', '')
@@ -649,7 +649,7 @@ async def role_agent_run(project_id, role, agent_id=None, model_name=None):
         ask_question = None
 
         # ── Tool Loop（原生 function calling）──
-        for turn in range(15):
+        for turn in range(30):
             try:
                 resp = await llm_call_msgs_native(msgs, tools=tools_schema, model=model_name, temperature=0.4)
             except Exception as e: