fix(firstleg): expose event bridge relay failures

firstleg/src/main/java/com/baiyue/firstleg/service/LoadingCompletedOutboxRelay.java

@@ -1,5 +1,6 @@
 package com.baiyue.firstleg.service;
 
+import com.baiyue.common.core.api.ApiResponse;
 import com.baiyue.common.event.EventEnvelope;
 import com.baiyue.common.event.EventEnvelopeValidator;
 import com.baiyue.firstleg.client.EventBridgeClient;
@@ -38,8 +39,7 @@ public class LoadingCompletedOutboxRelay {
                 EventEnvelope event=objectMapper.readValue(row.getPayloadJson(),EventEnvelope.class);
                 EventEnvelopeValidator.requireValid(event);
                 var response=client.receive(internalToken,event);
-                if(response==null || !response.successful() || response.data()==null
-                    || !event.eventId().equals(response.data().eventId())) throw new IllegalStateException("事件桥未确认头程跨区事件");
+                requireAcknowledgement(event, response);
                 repository.published(row.getId(),workerId,LocalDateTime.now());
             } catch(Exception exception) {
                 String error=safeError(exception);
@@ -50,11 +50,37 @@ public class LoadingCompletedOutboxRelay {
         }
     }
 
+    private void requireAcknowledgement(EventEnvelope event,
+                                        ApiResponse<EventBridgeClient.Acknowledgement> response) {
+        if(response==null) throw new IllegalStateException("事件桥未返回响应");
+        if(!response.successful()) {
+            throw new IllegalStateException("事件桥拒绝头程跨区事件: code=" + response.code()
+                + ", message=" + response.message() + ", requestId=" + response.requestId()
+                + ", traceId=" + response.traceId());
+        }
+        if(response.data()==null || !event.eventId().equals(response.data().eventId())) {
+            throw new IllegalStateException("事件桥 ACK 不匹配: expectedEventId=" + event.eventId()
+                + ", actualEventId=" + (response.data()==null?null:response.data().eventId()));
+        }
+    }
+
     private String safeError(Exception exception) {
-        String value=exception.getMessage();
-        if(value==null || value.isBlank()) value=exception.getClass().getSimpleName();
+        Throwable diagnostic=diagnosticCause(exception);
+        String message=diagnostic.getMessage();
+        String value=diagnostic.getClass().getSimpleName()
+            + ((message==null || message.isBlank())?"":": " + message);
         if(internalToken!=null && !internalToken.isBlank()) value=value.replace(internalToken,"***");
         value=value.replaceAll("[\\r\\n\\t]+"," ");
         return value.length()>500?value.substring(0,500):value;
     }
+
+    private Throwable diagnosticCause(Throwable failure) {
+        Throwable current=failure;
+        while(current.getCause()!=null && current.getCause()!=current
+            && ("NoFallbackAvailableException".equals(current.getClass().getSimpleName())
+                || "No fallback available.".equals(current.getMessage()))) {
+            current=current.getCause();
+        }
+        return current;
+    }
 }