diff --git a/runnables/composite/runner.go b/runnables/composite/runner.go
index c759c8c..4ca1c87 100644
--- a/runnables/composite/runner.go
+++ b/runnables/composite/runner.go
@@ -111,7 +111,7 @@ func (r *Runner[T]) Run(ctx context.Context) error {
 	}
 
 	// Start all child runnables
-	if err := r.boot(ctx); err != nil {
+	if err := r.boot(runCtx); err != nil {
 		r.setStateError()
 		return fmt.Errorf("failed to start child runnables: %w", err)
 	}
@@ -128,7 +128,8 @@ func (r *Runner[T]) Run(ctx context.Context) error {
 		r.logger.Debug("Local context canceled")
 	case err := <-r.serverErrors:
 		r.setStateError()
-		return fmt.Errorf("%w: %w", ErrRunnableFailed, err)
+		stopErr := r.stopAllRunnables()
+		return fmt.Errorf("%w: %w", ErrRunnableFailed, errors.Join(err, stopErr))
 	}
 
 	if err := r.fsm.TransitionIfCurrentState(finitestate.StatusRunning, finitestate.StatusStopping); err != nil {
diff --git a/runnables/composite/runner_test.go b/runnables/composite/runner_test.go
index d9c08f1..edb26a6 100644
--- a/runnables/composite/runner_test.go
+++ b/runnables/composite/runner_test.go
@@ -204,6 +204,7 @@ func TestCompositeRunner_Run(t *testing.T) {
 			// Wait until context is cancelled
 			<-args.Get(0).(context.Context).Done()
 		}).Return(nil)
+		mockRunnable1.On("Stop").Once()
 
 		// Create entries
 		entries := []RunnableEntry[*mocks.Runnable]{
@@ -235,6 +236,7 @@ func TestCompositeRunner_Run(t *testing.T) {
 		mockRunnable := mocks.NewMockRunnable()
 		mockRunnable.On("String").Return("runnable1")
 		mockRunnable.On("Run", mock.Anything).Return(errors.New("failed to start"))
+		mockRunnable.On("Stop").Once()
 
 		entries := []RunnableEntry[*mocks.Runnable]{
 			{Runnable: mockRunnable, Config: nil},
@@ -498,6 +500,125 @@ func TestCompositeRunner_Stop(t *testing.T) {
 	})
 }
 
+func TestCompositeRunner_StopCancelsChildContexts(t *testing.T) {
+	t.Parallel()
+	synctest.Test(t, func(t *testing.T) {
+		childDone := make(chan struct{}, 2)
+
+		mock1 := mocks.NewMockRunnable()
+		mock1.On("String").Return("r1")
+		mock1.On("Run", mock.Anything).Run(func(args mock.Arguments) {
+			<-args.Get(0).(context.Context).Done()
+			childDone <- struct{}{}
+		}).Return(nil)
+		mock1.On("Stop").Once()
+
+		mock2 := mocks.NewMockRunnable()
+		mock2.On("String").Return("r2")
+		mock2.On("Run", mock.Anything).Run(func(args mock.Arguments) {
+			<-args.Get(0).(context.Context).Done()
+			childDone <- struct{}{}
+		}).Return(nil)
+		mock2.On("Stop").Once()
+
+		entries := []RunnableEntry[*mocks.Runnable]{
+			{Runnable: mock1},
+			{Runnable: mock2},
+		}
+
+		configCallback := func() (*Config[*mocks.Runnable], error) {
+			return NewConfig("test", entries)
+		}
+
+		runner, err := NewRunner(configCallback)
+		require.NoError(t, err)
+
+		errCh := make(chan error, 1)
+		go func() {
+			errCh <- runner.Run(t.Context())
+		}()
+
+		time.Sleep(10 * time.Millisecond)
+		synctest.Wait()
+
+		assert.Equal(t, finitestate.StatusRunning, runner.GetState())
+
+		runner.Stop()
+
+		time.Sleep(10 * time.Millisecond)
+		synctest.Wait()
+
+		select {
+		case err := <-errCh:
+			require.NoError(t, err)
+		default:
+			t.Fatal("Run did not return after Stop — children may not derive from runCtx")
+		}
+
+		for range 2 {
+			select {
+			case <-childDone:
+			default:
+				t.Fatal("child goroutine did not exit after Stop")
+			}
+		}
+
+		mock1.AssertExpectations(t)
+		mock2.AssertExpectations(t)
+	})
+}
+
+func TestCompositeRunner_ErrorPathStopsSiblings(t *testing.T) {
+	t.Parallel()
+	synctest.Test(t, func(t *testing.T) {
+		survivor := mocks.NewMockRunnable()
+		survivor.On("String").Return("survivor")
+		survivor.On("Run", mock.Anything).Run(func(args mock.Arguments) {
+			<-args.Get(0).(context.Context).Done()
+		}).Return(nil)
+		survivor.On("Stop").Once()
+
+		failer := mocks.NewMockRunnable()
+		failer.On("String").Return("failer")
+		failer.On("Run", mock.Anything).Run(func(args mock.Arguments) {
+			time.Sleep(50 * time.Millisecond)
+		}).Return(errors.New("boom"))
+		failer.On("Stop").Once()
+
+		entries := []RunnableEntry[*mocks.Runnable]{
+			{Runnable: survivor},
+			{Runnable: failer},
+		}
+
+		configCallback := func() (*Config[*mocks.Runnable], error) {
+			return NewConfig("test", entries)
+		}
+
+		runner, err := NewRunner(configCallback)
+		require.NoError(t, err)
+
+		errCh := make(chan error, 1)
+		go func() {
+			errCh <- runner.Run(t.Context())
+		}()
+
+		time.Sleep(60 * time.Millisecond)
+		synctest.Wait()
+
+		select {
+		case err := <-errCh:
+			require.Error(t, err)
+			require.ErrorIs(t, err, ErrRunnableFailed)
+			require.ErrorContains(t, err, "boom")
+		default:
+			t.Fatal("Run should have returned error from failing child")
+		}
+
+		survivor.AssertExpectations(t)
+		failer.AssertExpectations(t)
+	})
+}
+
 func TestCompositeRunner_MultipleChildFailures(t *testing.T) {
 	t.Parallel()
 	synctest.Test(t, func(t *testing.T) {
@@ -510,6 +631,7 @@ func TestCompositeRunner_MultipleChildFailures(t *testing.T) {
 			started <- struct{}{}
 			time.Sleep(20 * time.Millisecond)
 		}).Return(failErr)
+		mockRunnable1.On("Stop").Once()
 
 		mockRunnable2 := mocks.NewMockRunnable()
 		mockRunnable2.On("String").Return("failer2")
@@ -517,6 +639,7 @@ func TestCompositeRunner_MultipleChildFailures(t *testing.T) {
 			started <- struct{}{}
 			time.Sleep(20 * time.Millisecond)
 		}).Return(failErr)
+		mockRunnable2.On("Stop").Once()
 
 		mockRunnable3 := mocks.NewMockRunnable()
 		mockRunnable3.On("String").Return("failer3")
@@ -524,6 +647,7 @@ func TestCompositeRunner_MultipleChildFailures(t *testing.T) {
 			started <- struct{}{}
 			time.Sleep(20 * time.Millisecond)
 		}).Return(failErr)
+		mockRunnable3.On("Stop").Once()
 
 		entries := []RunnableEntry[*mocks.Runnable]{
 			{Runnable: mockRunnable1},