feat(process): preserve wait task snapshots on failure

actions.go

@@ -91,6 +91,8 @@ type TaskProcessGet struct {
 }
 
 // TaskProcessWait waits for a managed process to finish through Core.PERFORM.
+// Successful exits return an Info snapshot. Unsuccessful exits return a
+// TaskProcessWaitError value that preserves the final snapshot.
 //
 // Example:
 //
@@ -100,6 +102,30 @@ type TaskProcessWait struct {
 	ID string
 }
 
+// TaskProcessWaitError is returned as the task value when TaskProcessWait
+// completes with a non-successful process outcome. It preserves the final
+// process snapshot while still behaving like the underlying wait error.
+type TaskProcessWaitError struct {
+	Info Info
+	Err  error
+}
+
+// Error implements error.
+func (e *TaskProcessWaitError) Error() string {
+	if e == nil || e.Err == nil {
+		return ""
+	}
+	return e.Err.Error()
+}
+
+// Unwrap returns the underlying wait error.
+func (e *TaskProcessWaitError) Unwrap() error {
+	if e == nil {
+		return nil
+	}
+	return e.Err
+}
+
 // TaskProcessOutput requests the captured output of a managed process through Core.PERFORM.
 //
 // Example:

service.go

@@ -727,7 +727,13 @@ func (s *Service) handleTask(c *core.Core, task core.Task) core.Result {
 
 		info, err := s.Wait(m.ID)
 		if err != nil {
-			return core.Result{Value: err, OK: false}
+			return core.Result{
+				Value: &TaskProcessWaitError{
+					Info: info,
+					Err:  err,
+				},
+				OK: true,
+			}
 		}
 
 		return core.Result{Value: info, OK: true}

service_test.go

@@ -946,6 +946,28 @@ func TestService_OnStartup(t *testing.T) {
 		assert.Equal(t, 0, info.ExitCode)
 	})
 
+	t.Run("preserves final snapshot when process.wait task fails", func(t *testing.T) {
+		svc, c := newTestService(t)
+
+		err := svc.OnStartup(context.Background())
+		require.NoError(t, err)
+
+		proc, err := svc.Start(context.Background(), "sh", "-c", "exit 7")
+		require.NoError(t, err)
+
+		result := c.PERFORM(TaskProcessWait{ID: proc.ID})
+		require.True(t, result.OK)
+
+		errValue, ok := result.Value.(error)
+		require.True(t, ok)
+		var waitErr *TaskProcessWaitError
+		require.ErrorAs(t, errValue, &waitErr)
+		assert.Contains(t, waitErr.Error(), "process exited with code 7")
+		assert.Equal(t, proc.ID, waitErr.Info.ID)
+		assert.Equal(t, StatusExited, waitErr.Info.Status)
+		assert.Equal(t, 7, waitErr.Info.ExitCode)
+	})
+
 	t.Run("registers process.list task", func(t *testing.T) {
 		svc, c := newTestService(t)