CB-575: filter MCP cancellation warnings

bridged/src/main/java/dev/ltms/bridged/logging/McpCancelledNotificationFilter.java

@@ -0,0 +1,30 @@
+package dev.ltms.bridged.logging;
+
+import ch.qos.logback.classic.Level;
+import ch.qos.logback.classic.Logger;
+import ch.qos.logback.classic.turbo.TurboFilter;
+import ch.qos.logback.core.spi.FilterReply;
+import io.modelcontextprotocol.spec.McpSchema;
+import org.slf4j.Marker;
+
+/** Suppresses only the SDK warning for the normal MCP cancellation notification. */
+public final class McpCancelledNotificationFilter extends TurboFilter {
+
+    static final String LOGGER = "io.modelcontextprotocol.spec.McpStreamableServerSession";
+    static final String UNHANDLED_NOTIFICATION = "No handler registered for notification method: {}";
+
+    @Override
+    public FilterReply decide(Marker marker, Logger logger, Level level, String format, Object[] params,
+                              Throwable throwable) {
+        if (level == Level.WARN
+                && LOGGER.equals(logger.getName())
+                && UNHANDLED_NOTIFICATION.equals(format)
+                && params != null
+                && params.length == 1
+                && params[0] instanceof McpSchema.JSONRPCNotification notification
+                && "notifications/cancelled".equals(notification.method())) {
+            return FilterReply.DENY;
+        }
+        return FilterReply.NEUTRAL;
+    }
+}

bridged/src/main/resources/logback.xml

@@ -1,4 +1,13 @@
 <configuration>
+    <!--
+      CB-575: MCP SDK 2.0.0 has no public notification registration API. It registers only
+      notifications/initialized and notifications/roots/list_changed, so other client notifications
+      still warn when unhandled. Clients may legitimately send notifications/cancelled; suppress only
+      that SDK WARN because it would devalue the action-needed WARN level used by M4 fleet health.
+      If a later SDK handles cancellation, this filter simply stops matching and can be removed.
+    -->
+    <turboFilter class="dev.ltms.bridged.logging.McpCancelledNotificationFilter"/>
+
     <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
         <encoder>
             <pattern>%d{HH:mm:ss.SSS} %-5level [%thread] %logger{28} - %msg%n</pattern>

bridged/src/test/java/dev/ltms/bridged/logging/McpCancelledNotificationFilterTest.java

@@ -0,0 +1,37 @@
+package dev.ltms.bridged.logging;
+
+import ch.qos.logback.classic.Level;
+import ch.qos.logback.classic.Logger;
+import ch.qos.logback.classic.spi.ILoggingEvent;
+import ch.qos.logback.core.read.ListAppender;
+import io.modelcontextprotocol.spec.McpSchema;
+import org.junit.jupiter.api.Test;
+import org.slf4j.LoggerFactory;
+
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class McpCancelledNotificationFilterTest {
+
+    @Test
+    void suppressesOnlyTheCancelledNotificationWarning() {
+        Logger logger = (Logger) LoggerFactory.getLogger(McpCancelledNotificationFilter.LOGGER);
+        ListAppender<ILoggingEvent> appender = new ListAppender<>();
+        appender.start();
+        logger.addAppender(appender);
+        try {
+            logger.warn(McpCancelledNotificationFilter.UNHANDLED_NOTIFICATION,
+                    new McpSchema.JSONRPCNotification("notifications/cancelled", Map.of("requestId", 7)));
+            logger.warn(McpCancelledNotificationFilter.UNHANDLED_NOTIFICATION,
+                    new McpSchema.JSONRPCNotification("notifications/progress", Map.of("progress", 1)));
+
+            assertEquals(1, appender.list.size());
+            assertEquals(Level.WARN, appender.list.getFirst().getLevel());
+            assertTrue(appender.list.getFirst().getFormattedMessage().contains("notifications/progress"));
+        } finally {
+            logger.detachAppender(appender);
+        }
+    }
+}

bridged/src/test/resources/logback-test.xml

@@ -16,6 +16,9 @@
           AuditLogTest, which attaches its own ListAppender and asserts on emitted records.
     -->
 
+    <!-- Keep the test logger behaviour aligned with the production cancellation filter. -->
+    <turboFilter class="dev.ltms.bridged.logging.McpCancelledNotificationFilter"/>
+
     <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
         <encoder>
             <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
@@ -34,4 +37,4 @@
         <appender-ref ref="STDOUT"/>
     </root>
 
-</configuration>
+</configuration>