feat(agent): add executor evidence output contract

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

@@ -226,6 +226,53 @@ class ChatServiceSequentialAgentTest {
         assertTrue(chatModel.sawVerifierPrompt);
     }
 
+    @Test
+    void verifierReceivesStructuredExecutorPayloadFields() throws Exception {
+        ChatService chatService = createChatService();
+        ScriptedChatModel chatModel = new ScriptedChatModel();
+        chatModel.executorOutput = """
+                {
+                  "answer_version": "executor_evidence_v1",
+                  "diagnosis_summary": "已确认连接池 active 达到上限。",
+                  "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": [],
+                  "recommended_actions": [],
+                  "missing_info": [],
+                  "user_facing_answer": "已确认连接池 active 达到上限。"
+                }
+                """;
+
+        ChatService.ChatResult result = chatService.executeChatComplex(
+                chatModel,
+                new ToolCallback[0],
+                "请分析 MySQL 连接池耗尽",
+                List.of(),
+                "sequential-structured-executor-session"
+        );
+
+        assertEquals("已确认连接池 active 达到上限。", result.answer());
+        assertTrue(chatModel.verifierPromptText.contains("\"executor_structured_output\""));
+        assertTrue(chatModel.verifierPromptText.contains("\"executor_output_parse_status\""));
+        assertTrue(chatModel.verifierPromptText.contains("\"status\" : \"valid\""));
+        assertTrue(chatModel.verifierPromptText.contains("连接池 active 达到上限"));
+    }
+
     @Test
     void buildMethodToolsArrayIncludesLogsAndMetricsWhenAvailable() {
         ChatService chatService = new ChatService();
@@ -353,6 +400,7 @@ class ChatServiceSequentialAgentTest {
         private String plannerPromptText = "";
         private String executorPromptText = "";
         private String verifierPromptText = "";
+        private String executorOutput = "EXECUTOR_FINAL_ANSWER";
         private boolean sawVerifierPrompt;
         private final java.util.List<String> verifierOutputs;
         private int verifierOutputIndex;
@@ -396,7 +444,7 @@ class ChatServiceSequentialAgentTest {
             } else if (promptText.contains("EXECUTOR_TEST_PROMPT")) {
                 agentCalls.add("chat_executor");
                 executorPromptText = promptText;
-                text = "EXECUTOR_FINAL_ANSWER";
+                text = executorOutput;
             } else if (promptText.contains("VERIFIER_TEST_PROMPT")) {
                 agentCalls.add("chat_verifier");
                 verifierPromptText = promptText;