feat(agent): add executor evidence v2 contract

src/test/java/com/superbiz/agent/service/ChatServiceSequentialAgentTest.java

@@ -273,6 +273,63 @@ class ChatServiceSequentialAgentTest {
         assertTrue(chatModel.verifierPromptText.contains("连接池 active 达到上限"));
     }
 
+    @Test
+    void executeChatComplexRendersExecutorEvidenceV2InsteadOfRawJsonOnPass() throws Exception {
+        ChatService chatService = createChatService();
+        ScriptedChatModel chatModel = new ScriptedChatModel();
+        chatModel.executorOutput = """
+                {
+                  "answer_version": "executor_evidence_v2",
+                  "claims": [
+                    {
+                      "claim_id": "claim-1",
+                      "claim_type": "symptom",
+                      "claim_text": "连接池 active 达到上限",
+                      "support_level": "direct",
+                      "evidence_bindings": [
+                        {
+                          "source_type": "tool_trace",
+                          "source_id": "trace-1",
+                          "tool_name": "query_metrics",
+                          "source_invocation_ids": [101],
+                          "evidence_excerpt": "active=50 max=50"
+                        }
+                      ]
+                    }
+                  ],
+                  "hypotheses": [
+                    {
+                      "hypothesis_text": "连接泄漏可能参与了连接池耗尽",
+                      "basis": "已有连接池满载证据，但缺少泄漏检测日志",
+                      "needed_evidence": ["连接泄漏检测日志"]
+                    }
+                  ],
+                  "recommended_actions": [
+                    {
+                      "action_text": "补充查询连接池泄漏检测日志",
+                      "reason": "用于确认是否存在连接未释放"
+                    }
+                  ],
+                  "missing_info": ["缺少连接泄漏检测日志"]
+                }
+                """;
+
+        ChatService.ChatResult result = chatService.executeChatComplex(
+                chatModel,
+                new ToolCallback[0],
+                "请分析 MySQL 连接池耗尽",
+                List.of(),
+                "sequential-v2-render-session"
+        );
+
+        assertTrue(result.answer().contains("已确认信息"));
+        assertTrue(result.answer().contains("连接池 active 达到上限"));
+        assertTrue(result.answer().contains("可能方向"));
+        assertTrue(result.answer().contains("建议下一步"));
+        assertFalse(result.answer().contains("\"answer_version\""));
+        assertFalse(result.answer().contains("executor_evidence_v2"));
+    }
+
     @Test
     void buildMethodToolsArrayIncludesLogsAndMetricsWhenAvailable() {
         ChatService chatService = new ChatService();