Click-highlight layer is permanently detached after any layer-config change

[ckrew]

Click-highlight layer is permanently detached after any layer-config change

Where: reactapp/components/visualizations/Map.js (~lines 699-704, inside onMapClick)

if (highlightLayer.current) {
  highlightLayer.current.getSource().clear();
} else {
  highlightLayer.current = createHighlightLayer();
  map.addLayer(highlightLayer.current);
}

Mechanics: the layer-reconciliation effect in reactapp/components/map/Map.js (the layersToKeep/layersToRemove sweep, ~lines 281-290 and 540-542) removes any OL layer whose name is not in the configured layer list. highlightLayer is an imperative overlay, not a configured layer, so any layer-config rebuild (variable-input substitution changing a layer, adding/removing a layer, editing layer properties) detaches it from the map. The ref is never nulled, so the else branch never runs again — every subsequent click clears/adds features into a detached layer that renders nowhere.

User-visible effect: click-selection highlighting silently and permanently stops working after the first layer-config change that follows a click. (The marker layer does not have this bug — it is recreated and re-added on every click.)

Repro: click a feature (highlight appears) → change any variable input that rebuilds a layer, or edit a layer in the dashboard editor → click a feature again → no highlight.

[ckrew]

In reactapp/components/visualizations/Map.js, inside onMapClick (~line 699), the highlight layer is created and added to the OL map only when highlightLayer.current is null, and the ref is never nulled. The layer-reconciliation effect in reactapp/components/map/Map.js removes OL layers whose names are not in the configured layer list, which detaches this imperative overlay on any layer-config change. After that, every click clears/adds highlight features into a detached layer: click highlighting silently never renders again.

Fix by mirroring the attachment-check pattern this repo already uses for the snap-preview layer — see ensureSnapLayer in reactapp/components/visualizations/useSnapping.js: when the ref exists but !map.getLayers().getArray().includes(highlightLayer.current), re-add it with map.addLayer(...). Apply the same check at EVERY site that writes features into highlightLayer.current — search the file for all uses (onMapClick ~699, the hover path ~411, and the effect around ~442-464) and route them through one small ensureHighlightLayer(map) helper rather than duplicating the check. Do NOT modify the reconciliation sweep in reactapp/components/map/Map.js itself (exempting overlays there would change behavior for other layers and was deliberately rejected in the prior fix).

Tests: in reactapp/tests/components/visualizations/Map.test.js there is an existing test "snap preview re-attaches after being removed from the map (reconciliation sweep)" — mirror its shape for the highlight layer: click a feature (highlight layer attached, has features), remove the highlight layer from the map via mapRef.current.removeLayer(...) to simulate the sweep, click again, and assert the SAME layer instance is re-attached with the new highlight features. Follow the file's established dispatchEvent({type: "singleclick", coordinate, pixel}) + waitFor patterns and its existing mocks (queryLayerFeatures is mocked at the module level).

Constraints

• Do not change snapping behavior or useSnapping.js semantics; you may import/reuse its patterns only.
• Do not run git push; commit locally with conventional messages (fix(map): ...), one commit per bug.
• All existing tests must stay green (full suite ~2200 tests); run npm run lint and prettier on changed files.
• Both bugs were validated during a prior review — do not re-litigate whether they are real; the mechanics above were traced against the code. If the code has drifted and a description no longer matches, stop and report the mismatch instead of forcing the fix.