diff --git a/src/main/java/it/cnr/isti/workflow/manager/mcp/MCPAgentService.java b/src/main/java/it/cnr/isti/workflow/manager/mcp/MCPAgentService.java
index 2a8e7a2..7d730f6 100644
--- a/src/main/java/it/cnr/isti/workflow/manager/mcp/MCPAgentService.java
+++ b/src/main/java/it/cnr/isti/workflow/manager/mcp/MCPAgentService.java
@@ -595,6 +595,13 @@ public class MCPAgentService {
             Mono<Void> requestMono = client().delete()
                     .uri("/sessions/{sessionId}", sessionId)
                     .retrieve()
+                    // A session the bridge no longer has is the outcome this method wants, not a
+                    // failure to report: the bridge expires sessions on its own, so 404 is the
+                    // ordinary answer for anything the idle sweep reaches second. Treated as an
+                    // error it cost far more than noise - the removal below never ran, so the sweep
+                    // retried the same dead session every minute forever, and each attempt counted
+                    // against the circuit breaker that guards real MCP calls.
+                    .onStatus(status -> status.value() == 404, clientResponse -> Mono.empty())
                     .onStatus(status -> status.isError(), clientResponse -> clientResponse.bodyToMono(String.class)
                             .defaultIfEmpty("MCP bridge returned an error without body")
                         .flatMap(body -> {
diff --git a/src/test/java/it/cnr/isti/workflow/manager/mcp/MCPAgentServiceTest.java b/src/test/java/it/cnr/isti/workflow/manager/mcp/MCPAgentServiceTest.java
index ea4c58b..4d0d9ed 100644
--- a/src/test/java/it/cnr/isti/workflow/manager/mcp/MCPAgentServiceTest.java
+++ b/src/test/java/it/cnr/isti/workflow/manager/mcp/MCPAgentServiceTest.java
@@ -185,6 +185,38 @@ class MCPAgentServiceTest {
         assertTrue(documentError.getMessage().contains("must be PDF"));
     }
 
+    @Test
+    void closingASessionTheBridgeNoLongerHasStopsTrackingIt() throws Exception {
+        // The bridge expires sessions on its own, so the idle sweep regularly finds one already
+        // gone. Treating that 404 as a failure left the session in activeSessions, so the sweep
+        // retried the same dead session every minute forever - and every attempt counted against
+        // the circuit breaker that guards real MCP calls.
+        AtomicInteger deleteCalls = new AtomicInteger();
+        HttpServer bridge = HttpServer.create(new InetSocketAddress("127.0.0.1", 0), 0);
+        bridge.createContext("/sessions/gone-session", exchange -> {
+            deleteCalls.incrementAndGet();
+            assertEquals("DELETE", exchange.getRequestMethod());
+            writeJson(exchange, 404, "{\"detail\":\"Session gone-session not found\"}");
+        });
+        bridge.start();
+        try {
+            MCPAgentService service = serviceForBridge(bridge);
+            ReflectionTestUtils.setField(service, "closeTimeoutSeconds", 2L);
+            @SuppressWarnings("unchecked")
+            Map<String, Long> activeSessions =
+                    (Map<String, Long>) ReflectionTestUtils.getField(service, "activeSessions");
+            activeSessions.put("gone-session", System.currentTimeMillis());
+
+            service.closeSessionQuietly("gone-session");
+
+            assertEquals(1, deleteCalls.get());
+            assertFalse(activeSessions.containsKey("gone-session"),
+                    "a session the bridge has already dropped must not be swept again");
+        } finally {
+            bridge.stop(0);
+        }
+    }
+
     private MCPAgentService serviceForBridge(HttpServer bridge) throws Exception {
         MCPAgentService service = new MCPAgentService(
                 WebClient.builder(),