[Code health] Don't allow saving a duplicate vertex during polygon drawing session

[shobhitagarwal1612]

Towards #3679

Separate committed and tentative vertices in PolygonDrawingSession. This allows the persistence layer to safely store only the committed vertices without having to assume that the last vertex is user committed vertex or not.

Changes verified using unit tests and testing the flow on a physical device.

@andreia-ferreira PTAL?

[codecov]

Codecov Report

❌ Patch coverage is 91.42857% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 68.09%. Comparing base (6fa95fb) to head (ffb8a30).

Files with missing lines	Patch %	Lines
...lection/tasks/polygon/PolygonDrawingSessionImpl.kt	88.46%	0 Missing and 3 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #3750      +/-   ##
============================================
+ Coverage     68.06%   68.09%   +0.03%     
- Complexity     1613     1615       +2     
============================================
  Files           368      368              
  Lines          9528     9538      +10     
  Branches       1242     1244       +2     
============================================
+ Hits           6485     6495      +10     
  Misses         2376     2376              
  Partials        667      667              

Files with missing lines	Coverage Δ
...acollection/tasks/polygon/DrawAreaTaskViewModel.kt	82.43% <100.00%> (+0.11%)	⬆️
...acollection/tasks/polygon/PolygonDrawingSession.kt	100.00% <ø> (ø)
...lection/tasks/polygon/PolygonDrawingSessionImpl.kt	92.98% <88.46%> (-0.77%)	⬇️

... and 1 file with indirect coverage changes

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[andreia-ferreira]

I can't seem to close the polygons. When debugging i noticed that isSelfIntersecting now returns true when getting the state of the complete button. It could be because now this method checks displayVertices which includes the tentativeVertex, and that is equal to the first vertex

Screen_recording_20260521_143226.webm

[shobhitagarwal1612]

I'm unable to reproduce this on my device. Are you able to consistently reproduce it or is it flaky?

[andreia-ferreira]

it's consistently reproducible. But I've found out it's because I was clicking twice to drop the first point because clicking the first time doesn't make the white circle marker to show up until the camera is dragged. So I believe the problem is that dropping two points in the starting vertex is allowed, but then leads to an invalid polygon