feat(process): add wait task surface

Co-authored-by: Virgil <virgil@lethean.io>

actions.go

@@ -89,6 +89,16 @@ type TaskProcessGet struct {
 	ID string
 }
 
+// TaskProcessWait waits for a managed process to finish through Core.PERFORM.
+//
+// Example:
+//
+//	c.PERFORM(process.TaskProcessWait{ID: "proc-1"})
+type TaskProcessWait struct {
+	// ID identifies a managed process started by this service.
+	ID string
+}
+
 // TaskProcessOutput requests the captured output of a managed process through Core.PERFORM.
 //
 // Example:

global_test.go

@@ -273,6 +273,26 @@ func TestGlobal_Output(t *testing.T) {
 	assert.Contains(t, output, "global-output")
 }
 
+func TestGlobal_Wait(t *testing.T) {
+	svc, _ := newTestService(t)
+
+	old := defaultService.Swap(svc)
+	defer func() {
+		if old != nil {
+			defaultService.Store(old)
+		}
+	}()
+
+	proc, err := Start(context.Background(), "echo", "global-wait")
+	require.NoError(t, err)
+
+	info, err := Wait(proc.ID)
+	require.NoError(t, err)
+	assert.Equal(t, proc.ID, info.ID)
+	assert.Equal(t, StatusExited, info.Status)
+	assert.Equal(t, 0, info.ExitCode)
+}
+
 func TestGlobal_Signal(t *testing.T) {
 	svc, _ := newTestService(t)
 

process_global.go

@@ -114,6 +114,19 @@ func Output(id string) (string, error) {
 	return svc.Output(id)
 }
 
+// Wait blocks until a managed process exits and returns its final snapshot.
+//
+// Example:
+//
+//	info, err := process.Wait("proc-1")
+func Wait(id string) (Info, error) {
+	svc := Default()
+	if svc == nil {
+		return Info{}, ErrServiceNotInitialized
+	}
+	return svc.Wait(id)
+}
+
 // List returns all processes from the default service.
 //
 // Example:

service.go

@@ -529,6 +529,24 @@ func (s *Service) Output(id string) (string, error) {
 	return proc.Output(), nil
 }
 
+// Wait blocks until a managed process exits and returns its final snapshot.
+//
+// Example:
+//
+//	info, err := svc.Wait("proc-1")
+func (s *Service) Wait(id string) (Info, error) {
+	proc, err := s.Get(id)
+	if err != nil {
+		return Info{}, err
+	}
+
+	if err := proc.Wait(); err != nil {
+		return proc.Info(), err
+	}
+
+	return proc.Info(), nil
+}
+
 // findByPID locates a managed process by operating-system PID.
 func (s *Service) findByPID(pid int) *Process {
 	s.mu.RLock()
@@ -672,6 +690,17 @@ func (s *Service) handleTask(c *core.Core, task core.Task) core.Result {
 		}
 
 		return core.Result{Value: proc.Info(), OK: true}
+	case TaskProcessWait:
+		if m.ID == "" {
+			return core.Result{Value: coreerr.E("Service.handleTask", "task process wait requires an id", nil), OK: false}
+		}
+
+		info, err := s.Wait(m.ID)
+		if err != nil {
+			return core.Result{Value: err, OK: false}
+		}
+
+		return core.Result{Value: info, OK: true}
 	case TaskProcessOutput:
 		if m.ID == "" {
 			return core.Result{Value: coreerr.E("Service.handleTask", "task process output requires an id", nil), OK: false}

service_test.go

@@ -597,6 +597,41 @@ func TestService_Output(t *testing.T) {
 	})
 }
 
+func TestService_Wait(t *testing.T) {
+	t.Run("returns final info on success", func(t *testing.T) {
+		svc, _ := newTestService(t)
+
+		proc, err := svc.Start(context.Background(), "echo", "waited")
+		require.NoError(t, err)
+
+		info, err := svc.Wait(proc.ID)
+		require.NoError(t, err)
+		assert.Equal(t, proc.ID, info.ID)
+		assert.Equal(t, StatusExited, info.Status)
+		assert.Equal(t, 0, info.ExitCode)
+	})
+
+	t.Run("returns error on unknown id", func(t *testing.T) {
+		svc, _ := newTestService(t)
+
+		_, err := svc.Wait("nonexistent")
+		assert.ErrorIs(t, err, ErrProcessNotFound)
+	})
+
+	t.Run("returns info alongside failure", func(t *testing.T) {
+		svc, _ := newTestService(t)
+
+		proc, err := svc.Start(context.Background(), "sh", "-c", "exit 7")
+		require.NoError(t, err)
+
+		info, err := svc.Wait(proc.ID)
+		require.Error(t, err)
+		assert.Equal(t, proc.ID, info.ID)
+		assert.Equal(t, StatusExited, info.Status)
+		assert.Equal(t, 7, info.ExitCode)
+	})
+}
+
 func TestService_OnShutdown(t *testing.T) {
 	t.Run("kills all running processes", func(t *testing.T) {
 		svc, _ := newTestService(t)
@@ -770,6 +805,25 @@ func TestService_OnStartup(t *testing.T) {
 		assert.Equal(t, StatusKilled, proc.Status)
 	})
 
+	t.Run("registers process.wait task", func(t *testing.T) {
+		svc, c := newTestService(t)
+
+		err := svc.OnStartup(context.Background())
+		require.NoError(t, err)
+
+		proc, err := svc.Start(context.Background(), "echo", "action-wait")
+		require.NoError(t, err)
+
+		result := c.PERFORM(TaskProcessWait{ID: proc.ID})
+		require.True(t, result.OK)
+
+		info, ok := result.Value.(Info)
+		require.True(t, ok)
+		assert.Equal(t, proc.ID, info.ID)
+		assert.Equal(t, StatusExited, info.Status)
+		assert.Equal(t, 0, info.ExitCode)
+	})
+
 	t.Run("registers process.list task", func(t *testing.T) {
 		svc, c := newTestService(t)