LmControl API - Support callback registration before connection

score/launch_manager/src/lm_control/src/details/lm_control_impl.hpp

@@ -215,8 +215,12 @@ class BasicLmControlImpl final : public ILmControl
             callback_ = std::move(callback);
         }
 
-        // Check for any pending events from before the handler was installed.
-        onActivationResult();
+        // Check for any pending events from before the handler was installed. Only possible once connected;
+        // until then the receive handler, installed on connection, takes care of the samples.
+        if (connectedProxy() != nullptr)
+        {
+            onActivationResult();
+        }
 
         return {};
     }

score/launch_manager/src/lm_control/src/details/lm_control_impl_UT.cpp

@@ -674,6 +674,36 @@ TEST_F(LmControlUT, RegisterEmptyCallbackRejected)
     EXPECT_EQ(result.error(), ExecErrc::kInvalidArguments);
 }
 
+TEST_F(LmControlUT, CallbackRegisteredBeforeConnectionIsUsedOnceConnected)
+{
+    RecordProperty(
+        "Description",
+        "Registering an activation callback before the service is discovered succeeds without reading samples, "
+        "and the callback receives activation results once connected.");
+
+    auto sut = MakeLmControl();
+
+    std::optional<RunTargetName> name{};
+    EXPECT_CALL(mock_, GetNewSamples(_)).Times(0);
+    ASSERT_TRUE(sut->register_run_target_activation_callback([&](RunTargetActivationSource, RunTargetName n) {
+                       name = n;
+                   })
+                    .has_value());
+    ::testing::Mock::VerifyAndClearExpectations(&mock_);
+
+    ConnectService();
+
+    EXPECT_CALL(mock_, GetNewSamples(_)).WillOnce(Invoke([](std::size_t) {
+        return score::Result<std::vector<ActivationResult>>{MakeSamples({"Running"})};
+    }));
+
+    ASSERT_TRUE(receive_handler_);
+    receive_handler_();
+
+    ASSERT_TRUE(name.has_value());
+    EXPECT_EQ(name.value(), "Running");
+}
+
 TEST_F(LmControlUT, ActivationResultInvokesRegisteredCallback)
 {
     RecordProperty(