fix(appointment): retain safe synchronization failure diagnostics

lastleg-service/src/main/java/com/baiyue/lastleg/appointmentwork/AppointmentWorkSynchronizationJob.java

@@ -21,7 +21,20 @@ public class AppointmentWorkSynchronizationJob {
             cursor=result.complete()?null:result.nextCursor();
         } catch(RuntimeException error) {
             cursor=null;
-            log.warn("Appointment work synchronization incomplete; next scan restarts from first page: {}",error.getClass().getSimpleName());
+            log.warn("Appointment work synchronization incomplete; next scan restarts from first page: {}",failureDiagnostic(error));
         }
     }
+    /** Keep causes and code locations, never exception messages that may contain remote payloads or credentials. */
+    static String failureDiagnostic(Throwable error) {
+        var causes=new java.util.ArrayList<String>();
+        var seen=java.util.Collections.newSetFromMap(new java.util.IdentityHashMap<Throwable,Boolean>());
+        for(var current=error;current!=null && causes.size()<6 && seen.add(current);current=current.getCause()) {
+            String status=current instanceof org.springframework.web.server.ResponseStatusException response?"["+response.getStatusCode().value()+"]":"";
+            String location=java.util.Arrays.stream(current.getStackTrace())
+                .filter(frame->frame.getClassName().startsWith("com.baiyue.") && !frame.getClassName().equals(AppointmentWorkPolicy.class.getName()))
+                .findFirst().map(frame->"@"+frame.getClassName()+":"+frame.getLineNumber()).orElse("");
+            causes.add(current.getClass().getSimpleName()+status+location);
+        }
+        return String.join(" <- ",causes);
+    }
 }

lastleg-service/src/test/java/com/baiyue/lastleg/appointmentwork/AppointmentWorkSynchronizationJobTest.java

@@ -0,0 +1,16 @@
+package com.baiyue.lastleg.appointmentwork;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.http.HttpStatus;
+import org.springframework.web.server.ResponseStatusException;
+import static org.assertj.core.api.Assertions.assertThat;
+
+class AppointmentWorkSynchronizationJobTest {
+    @Test void diagnosticKeepsCauseAndCodeWithoutRemoteMessages() {
+        var cause=new IllegalArgumentException("Authorization: Bearer secret; private remote body");
+        var error=new ResponseStatusException(HttpStatus.SERVICE_UNAVAILABLE,"private response",cause);
+        assertThat(AppointmentWorkSynchronizationJob.failureDiagnostic(error))
+            .contains("ResponseStatusException[503]", "IllegalArgumentException", "AppointmentWorkSynchronizationJobTest:")
+            .doesNotContain("secret", "private", "Authorization", "Bearer");
+    }
+}