Fix ad hoc mesh infinite loading (#8915)

This PR avoids requesting out-of-bounds ad hoc mesh chunks in an
infinite loop.

### URL of deployed dev instance (used for testing):
- https://fixadhocmeshinfiniteloading.webknossos.xyz

### Steps to test:
- Best to test locally with a dataset without segment index
- please not, that ad hoc meshing is bug for transformed datasets. See
#8913.
- checkout 3fc42bd to have a
visualization of what happens on the master
- View a dataset without a segment index. 
- Load some segments ad hoc mesh. Watch boxes appear -> infinitely mesh
requests e.g. going more and more out of bounds.
- Note: The bounds of the boxes are not correct but still helpful to see
at what coordinates mesh chunk requests are sent.
- check out 67f2060 and do the same
again after reload
- now no boxes outside of the segmentation layer should be requested and
the request should terminate rather quickly

### TODOs:
- [x] remove debug bboxes code

### Issues:
- fixes reported here:
https://scm.slack.com/archives/C02H5T8Q08P/p1757417432537409?thread_ts=1757338710.530969&cid=C02H5T8Q08P

------
(Please delete unneeded items, merge only when none are left open)
- [x] Added changelog entry (create a `$PR_NUMBER.md` file in
`unreleased_changes` or use `./tools/create-changelog-entry.py`)

---------

Co-authored-by: Daniel <[email protected]>

Author: MichaelBuessemeyer

frontend/javascripts/test/global_mocks.ts

@@ -22,6 +22,7 @@ vi.mock("libs/toast", () => ({
     success: vi.fn(),
     info: vi.fn(),
   },
+  showToastOnce: vi.fn(),
 }));
 
 vi.mock("libs/user_local_storage", () => ({

frontend/javascripts/viewer/model/sagas/meshes/ad_hoc_mesh_saga.ts

@@ -429,8 +429,12 @@ function* maybeLoadMeshChunk(
 ): Saga<Vector3[]> {
   const additionalCoordinates = yield* select((state) => state.flycam.additionalCoordinates);
   const threeDMap = getOrAddMapForSegment(layer.name, segmentId, additionalCoordinates);
+  const mag = magInfo.getMagByIndexOrThrow(zoomStep);
+  const paddedPosition = V3.toArray(V3.sub(clippedPosition, mag));
+  const paddedPositionWithinLayer =
+    layer.cube.boundingBox.clipPositionIntoBoundingBox(paddedPosition);
 
-  if (threeDMap.get(clippedPosition)) {
+  if (threeDMap.get(paddedPositionWithinLayer)) {
     return [];
   }
 
@@ -439,7 +443,7 @@ function* maybeLoadMeshChunk(
   }
 
   batchCounterPerSegment[segmentId]++;
-  threeDMap.set(clippedPosition, true);
+  threeDMap.set(paddedPositionWithinLayer, true);
   const scaleFactor = yield* select((state) => state.dataset.dataSource.scale.factor);
   const dataStoreHost = yield* select((state) => state.dataset.dataStore.url);
   const datasetId = yield* select((state) => state.dataset.id);
@@ -449,8 +453,6 @@ function* maybeLoadMeshChunk(
   }`;
   const tracingStoreUrl = `${tracingStoreHost}/tracings/volume/${layer.name}`;
 
-  const mag = magInfo.getMagByIndexOrThrow(zoomStep);
-
   if (isInitialRequest) {
     sendAnalyticsEvent("request_isosurface", {
       mode: useDataStore ? "view" : "annotation",
@@ -462,9 +464,6 @@ function* maybeLoadMeshChunk(
   const { segmentMeshController } = getSceneController();
 
   const cubeSize = marchingCubeSizeInTargetMag();
-  const paddedPosition = V3.toArray(V3.sub(clippedPosition, mag));
-  const paddedPositionWithinLayer =
-    layer.cube.boundingBox.clipPositionIntoBoundingBox(paddedPosition);
 
   while (retryCount < MAX_RETRY_COUNT) {
     try {

unreleased_changes/8915.md

@@ -0,0 +1,2 @@
+### Fixed
+- Ad hoc mesh requests loading infinitely.