test(agentcompat): isolate stress resource sampling

Co-authored-by: naiba/CloudCode <hi+cloudcode@nai.ba>

integration/agentcompat/internal/scenario/held_session_set_real_fixture.go

@@ -40,7 +40,12 @@ func startHeldSessionSetRealFixture(ctx context.Context, paths contract.Paths, p
 	fixture.preparedBinary = prepared
 	for ordinal := 1; ordinal <= heldSessionSetAgentCount; ordinal++ {
 		uuid := fmt.Sprintf("00000000-0000-0000-0000-%012d", 700+ordinal)
-		instance, startErr := agent.Start(ctx, agent.AgentStartConfig{PreparedBinary: prepared, Endpoint: dashboardInstance.Endpoint(), Secret: dashboardInstance.AgentSecret(), UUID: uuid})
+		startConfig := canonicalHeldSessionAgentStartConfig()
+		startConfig.PreparedBinary = prepared
+		startConfig.Endpoint = dashboardInstance.Endpoint()
+		startConfig.Secret = dashboardInstance.AgentSecret()
+		startConfig.UUID = uuid
+		instance, startErr := agent.Start(ctx, startConfig)
 		if startErr != nil {
 			return nil, fixture.close(ctx, startErr)
 		}
@@ -81,6 +86,11 @@ func startHeldSessionSetRealFixture(ctx context.Context, paths contract.Paths, p
 	return fixture, nil
 }
 
+func canonicalHeldSessionAgentStartConfig() agent.AgentStartConfig {
+	// Connection counting opens short-lived NETLINK_INET_DIAG descriptors during state reports; exclude probes from stress residue snapshots.
+	return agent.AgentStartConfig{SkipConnectionCount: true}
+}
+
 func validateHeldSessionSetRealFixture(fixture *heldSessionSetRealFixture, plan StressPlan) error {
 	if fixture == nil || fixture.dashboard == nil || fixture.preparedBinary == nil || len(fixture.agents) != heldSessionSetAgentCount || len(fixture.readiness) != heldSessionSetAgentCount || len(fixture.agentPATs) != heldSessionSetAgentCount || len(fixture.controlServerIDs) != heldSessionSetAgentCount {
 		return errors.New("held session set real fixture is incomplete")

integration/agentcompat/internal/scenario/held_session_set_real_support_test.go

@@ -44,6 +44,14 @@ func TestHeldSessionSetRealPlanUsesCanonicalPRFullTopology(t *testing.T) {
 	}
 }
 
+func TestCanonicalHeldSessionAgentStartConfig_SkipsConnectionCount(t *testing.T) {
+	// When
+	actual := canonicalHeldSessionAgentStartConfig()
+
+	// Then
+	require.True(t, actual.SkipConnectionCount)
+}
+
 func TestHeldSessionSetRealEvidenceRejectsIncompleteAndRedactsArtifact(t *testing.T) {
 	root := t.TempDir()
 	require.NoError(t, os.Chmod(root, 0o700))