[Bug] First click after finishing polygon not registering (Google Maps adapter)

[oliveres]

Description

When using TerraDrawPolygonMode with TerraDrawGoogleMapsAdapter, the first click after completing a polygon (via double-click) is sometimes not registered. The user has to click twice to start drawing the next polygon.

This issue is intermittent - sometimes the first click works, sometimes it doesn't. The same behavior occurs on the first click after activating polygon mode.

Environment

• terra-draw: 1.19.0
• terra-draw-google-maps-adapter: 1.1.0
• @vis.gl/react-google-maps (React wrapper)
• Tested on:
  • macOS + Safari ✓ (issue present)
  • Windows + Chrome ✓ (issue present)

Steps to Reproduce

1. Initialize TerraDraw with Google Maps adapter and polygon mode
2. Wait for ready event before setting mode (as per docs)
3. Set mode to polygon
4. Draw a polygon and complete it with double-click
5. Immediately try to start drawing another polygon by clicking on the map
6. First click is sometimes ignored - polygon doesn't start drawing
7. Second click works and starts the new polygon

Expected Behavior

Every click after completing a polygon should register and start drawing a new polygon (when in polygon mode).

Actual Behavior

First click after completing a polygon (or after activating polygon mode) is sometimes ignored. The mode state shows started instead of transitioning to drawing.

Debug Information

Console logs show:
[PolygonTool] finish event, polygon completed
[PolygonTool] Mode state after finish: started
[PolygonTool] MAP CLICK - mode: polygon state: started ← Click registered by Google Maps but not processed by Terra Draw
[PolygonTool] MAP CLICK - mode: polygon state: drawing ← Second click works

The Google Maps click event fires, but Terra Draw doesn't process it. The getModeState() remains started instead of changing to drawing.

Minimal Reproduction Code

const draw = new TerraDraw({
  adapter: new TerraDrawGoogleMapsAdapter({
    map,
    lib: google.maps,
    coordinatePrecision: 9
  }),
  modes: [
    new TerraDrawPolygonMode({
      pointerDistance: 20,
    })
  ]
});

draw.start();

draw.on('ready', () => {
  draw.setMode('polygon');
});

draw.on('finish', (id) => {
  console.log('Polygon finished, state:', draw.getModeState());
  // State is 'started', ready for next polygon
  // But first click is sometimes ignored
});

Possible Cause

The issue might be related to:
1. Timing between double-click finish event and next single click
2. Internal state not fully reset after polygon completion
3. Event handling conflict between OverlayView and Google Maps click events

Workaround Attempts

- Tried calling setMode('select') then setMode('polygon') after finish - didn't help
- Tried increasing timeout before mode reset - didn't help
- Issue persists regardless of time waited between polygon completion and next click

[JamesLMilner]

Hey @oliveres - thanks for the issue. I wasn't able to reproduce it from experimenting for a few minutes, but I have some faint memories of seeing this before historically.

If you have any completely reproducible steps that would be helpful. I will try and look into it more deeply when I get some time.

[acorncom]

@oliveres I've been working on a few Google Maps integrations on other client apps and would be interested in tracking this down as well. I've likewise seen some periodic issues as you've described (have also been seeing a second click needed for starting a polygon). If you end up coming up with a reproduction repo, would love to see if we can work out what the issue is

[acenturionqisur]

Hi! I have the same issue described here. Sometimes the polygon drawing works normally, but I’ve noticed that when I move the map while the draw polygon mode is active, the state seems to break and it doesn’t register the first click. In some cases, it doesn’t work with any click at all until I reset the draw polygon mode.

[JamesLMilner]

I don't have any further insight into why this might be - if anyone has any additional insight into the potential cause I'd be open to discussing in more detail.

[EduNauta]

I (the AI) recently solved a similar bug, which may or may not provide a clue to what is happening here.

✅ Grouper: Google Maps 2-Click Deselect - FIXED (2026-03-21)
I kept bashing cursor's auto model until it solved it somehow.
Problem: On Google Maps, when a GeoJSON territorial layer (example: country provinces) is active, territory deselection sometimes required two clicks (clicking empty map/sea twice), while Leaflet and Mapbox deselected on one click.
Root cause: Google maps click handling was mixing polygon-click suppression with normal empty-map deselect flow, causing valid first deselect clicks to be skipped.
Fix: Refined the Google empty-map deselect guard to skip only same-point polygon-bubble duplicates (short window + matching click coordinates) and allow real empty-map clicks to run resetTerritoryInfo() immediately.

---

I also have found another earlier AI documentation listing all the failed attempts at fixing the bug, so you can know how not to fix it. Big part of the text below are attempts in the dark as you can see:

Google Maps: 2-Click Deselect During Group Creation (UNFIXED)

Problem: In Google Maps, deselecting a territory requires two clicks instead of one. Leaflet and Mapbox work correctly with a single click.

Attempts made (all unsuccessful):

1. addTerritoryToSelection logic

   • Same type+name → deselect
   • Same name + lower/equal priority (overlapping layers) → deselect
   • Remove all with same type+name when deselecting
   • __lastDeselectAt / __lastDeselectName guard to block re-adds after deselect

2. clearTerritorySelection

   • For Google: call clearGroupHighlights() and re-apply visible groups when clearing selection

3. Google polygon click handler

   • Immediate handling with __groupsClickProcessed to avoid double handling
   • Inline deselect in the handler (bypass addTerritoryToSelection)
   • e.domEvent.stopPropagation()
   • Cancel map click timeout when polygon is clicked (clearTimeout in __googlePolygonClickHandled)

4. Empty map click

   • When in group creation and selection exists, call clearTerritorySelection() on empty map click (Google, Leaflet, Mapbox) — this was implemented and works; it provides a workaround but does not fix the 2-click deselect on the territory itself

5. Simplification (Edumapa-style)

   • addTerritoryToSelection reduced to: findIndex by (type, name, featureId) → add or splice
   • Polygon handler simplified to direct addTerritoryToSelection call
   • Minimal __googlePolygonJustProcessed guard (50ms) for MultiPolygon parts

Reference: Early Projects/Websites/Edumapa/Edumapa.html uses a simple flow: polygon click → selectFeatureFromMap → addTerritoryToSelection with findIndex by (type, name, featureId) and splice for toggle. No priority logic, no setTimeout, no claim logic. Edumapa may use Leaflet only; the Google Maps Data layer / polygon event model may differ in ways that cause the double-handling.

Hypothesis for future investigation: Google Maps polygon click events may fire differently (e.g., once per polygon part in MultiPolygon, or map click + polygon click in sequence) such that the first click triggers deselect but a subsequent event re-adds the territory. Tracing the exact event order and handler invocation sequence on Google Maps would be the next diagnostic step.