### Note

Begin of the insertion1. Not sure ifEnd of the insertion Begin of the deletion InEnd of the deletion this Begin of the insertionisEnd of the insertion bug Begin of the insertionreport or a feature request. We might come toEnd of the insertion Begin of the deletion report,End of the deletion the Begin of the insertionconclusion to move this to another version.
2. TheEnd of the insertion word Begin of the insertiondistanceEnd of the insertion Begin of the deletion "lag"End of the deletion is used to describe the number of days between two related Begin of the insertionpackages (implicit). It is notEnd of the insertion Begin of the deletion packages; internally,End of the deletion the Begin of the insertion(explicit) lag between two work packages.End of the insertion Begin of the deletion word "delay" might be used by the dev team.End of the deletion There is currently no UI representation for Begin of the insertionthe lag attribute. The lagEnd of the insertion Begin of the deletion this value, although itEnd of the deletion can Begin of the insertiononlyEnd of the insertion Begin of the deletion indirectlyEnd of the deletion be Begin of the insertionCRUDEnd of the insertion Begin of the deletion setEnd of the deletion using the Begin of the insertionAPI.
3. In the API and the database lag is currently named "Delay": ##44054End of the insertion Begin of the deletion Gantt chart (as described below).End of the deletion

### Steps to reproduce

1. Go to the _Work packages_ module and activate Gantt view.
2. Create two work packages (wp1 and wp2).
3. Give wp1 and wp2 the same start and finish dates, with a duration of 2 days.
4. Add a relation so that wp2 "follows" wp1.
* Wp2's start and finish dates will change as a result, such that wp2 starts the next available day after wp1's finish date.
5. Move wp2 into the future so that there are 4 days in between wp1 and wp2 Begin of the insertion(distanceEnd of the insertion Begin of the deletion (lagEnd of the deletion = 3 days).
6. **Adjustment 1:** Move wp1 two days into the future. Note that this does not push wp2 by two days; instead, the Begin of the insertion**distance** _**isEnd of the insertion Begin of the deletion _**lag isEnd of the deletion reduced**_ from 3 days to 1 day (two days in between).
7. **Adjustment 2:** Now move wp1 two days into the past. Note that in this case, this pulls wp2 ahead by two days; a Begin of the insertion**distance** _**ofEnd of the insertion Begin of the deletion _**lag ofEnd of the deletion 1 day is conserved**_ (2 days in between).
8. **Adjustment 3:** Now move wp1 such that it's start date is past the start date of wp. Note that wp2 is pushed so that it starts the first available day after wp1 ends, Begin of the insertion**disctanceEnd of the insertion Begin of the deletion **lagEnd of the deletion is set to zero.**

### What is the buggy behavior?

* When Begin of the insertionthe distanceEnd of the insertion Begin of the deletion lagEnd of the deletion is set by moving wp2 into the future on the Gantt chart, the behaviour is not consistent between when wp1 is moved backwards or fowards in time (between adjustment 1 and 2).
* Moving wp1 into the past changes start/finish dates of wp2 and conserves Begin of the insertiondistance.End of the insertion Begin of the deletion lag.End of the deletion
* Moving wp1 into the future preserves start/finish dates of wp2 and reduces Begin of the insertiondistance.End of the insertion Begin of the deletion lag.End of the deletion
* Note that in the case of adjustment 3 (wp1 moved beyond wp2), the work packages are rescheduled as expected (wp2 starts 1 day after wp1, lag = 0).

### What is the expected behavior?

Begin of the deletion For adjustments 1 and 2, either:

End of the deletion * Begin of the insertionThe distanceEnd of the insertion Begin of the deletion **Solution 1:** lagEnd of the deletion is Begin of the insertionnot preserved whenEnd of the insertion Begin of the deletion conserved in both cases (soEnd of the deletion moving Begin of the insertionwp 1 intoEnd of the insertion Begin of the deletion wp1 forwards or backwards should pull/push wp2 byEnd of the deletion the Begin of the insertionpast.
End of the insertion Begin of the deletion same number of days)
End of the deletion * Begin of the insertionWP2 is only rescheduled ifEnd of the insertion Begin of the deletion This also means we need to come up with a way to allow users to view and edit this lag manually, possibly inEnd of the deletion the Begin of the insertionchange of WP1 would create a negative distance (distance <0).

## Next step - out of scope

End of the insertion Begin of the deletion Relations tab.
End of the deletion * Begin of the insertionWe implementEnd of the insertion Begin of the deletion **Solution 2:** lag is ignored in both cases (andEnd of the deletion a Begin of the insertionuser interface to CRUDEnd of the insertion Begin of the deletion follows/preceeds relationship always forces a 0-day lag, and wp2 always startsEnd of the deletion the Begin of the insertionexisting lag attribute.End of the insertion Begin of the deletion first available day after wp1).

Further discussion needed.End of the deletion

### Screenshots and other files

This screencap illustrates steps 5–8 of 'Steps to reproduce':

<img class="op-uc-image op-uc-image_inline" src="/api/v3/attachments/38374/content">

### Environment information

**OpenProject installation type**

All

**OpenProject version**

12.2