feat(cyclones): publish explicit selection to shared context

src/layers/cyclones/index.test.mjs

@@ -338,7 +338,7 @@ test('a click on a storm card or lead-hour label selects that storm without pick
 });
 function harness(
   feed = { getSnapshot: async () => snapshot() },
-  { reducedMotion = false } = {},
+  { reducedMotion = false, context = null } = {},
 ) {
   const applied = [],
     navigation = [],
@@ -368,6 +368,7 @@ function harness(
   };
   const layer = createCyclonesLayer({
     feed,
+    context,
     createRendering: () => rendering,
     matchMedia: () => ({ matches: reducedMotion }),
     openLink: (url) => opened.push(url),
@@ -401,6 +402,75 @@ function harness(
     },
   };
 }
+test('explicit cyclone selection publishes shared context without auto-claiming it', async () => {
+  let next = snapshot([storm(), storm('ep162026')]);
+  const records = new Map();
+  let selectedContext = null;
+  let selectedEvents = 0;
+  const context = {
+    registerEntityContext(entity, metadata) {
+      entity.__gevContextId = metadata.id;
+      const record = { ...metadata, entity };
+      records.set(metadata.id, record);
+      return record;
+    },
+    selectEntityContext(entity) {
+      selectedContext = records.get(entity.__gevContextId) || null;
+      selectedEvents += 1;
+      return selectedContext;
+    },
+    removeEntityContextsForLayer(layerId) {
+      for (const [id, record] of records) {
+        if (record.layerId === layerId) records.delete(id);
+      }
+      if (selectedContext?.layerId === layerId) selectedContext = null;
+    },
+  };
+  const h = harness({ getSnapshot: async () => next }, { context });
+  h.layer.enable();
+  await h.layer.update();
+
+  assert.equal(
+    selectedEvents,
+    0,
+    'the automatic first-storm row selection must not claim shared context',
+  );
+  assert.equal(records.size, 0);
+
+  h.layer.setParams({ stormId: 'ep162026' });
+  assert.equal(selectedEvents, 1);
+  assert.equal(selectedContext?.layerId, 'weather-cyclones');
+  assert.equal(selectedContext?.source, 'NOAA NHC / CPHC');
+  assert.equal(selectedContext?.label, 'Cyclone · Another system');
+  assert.equal(selectedContext?.latitude, 15.5);
+  assert.equal(selectedContext?.longitude, -125.8);
+  assert.equal(selectedContext?.properties.advisoryNumber, '10');
+
+  await h.layer.update();
+  assert.equal(
+    selectedEvents,
+    1,
+    'refresh updates the selected record without re-announcing the click',
+  );
+
+  next = snapshot([storm()]);
+  await h.layer.update();
+  assert.equal(
+    selectedContext,
+    null,
+    'a vanished user-selected storm must clear instead of transferring context to the fallback row',
+  );
+  assert.equal(records.size, 0);
+
+  h.layer.setParams({ stormId: 'ep152026' });
+  assert.equal(selectedEvents, 2);
+  h.layer.setParams({ clear: true });
+  assert.equal(selectedContext, null);
+  assert.equal(records.size, 0);
+
+  h.layer.destroy();
+});
+
 test('refresh preserves selection intent, including explicit clears and missing storms', async () => {
   let next = snapshot([storm(), storm('ep162026')]);
   const h = harness({ getSnapshot: async () => next });