refactor: supply application catalogs explicitly

src/app/catalog.js

@@ -0,0 +1,58 @@
+const CONTROL_LAYER_IDS = Object.freeze({
+  trafficLayer: 'traffic',
+  flightsLayer: 'flights',
+  militaryFlightsLayer: 'military',
+  satellitesLayer: 'satellites',
+  cctvLayer: 'cctv',
+  radioLayer: 'radio',
+  bikeshareLayer: 'bikeshare',
+  aisLiveVesselsLayer: 'ais-live-vessels',
+  militaryAwarenessLayer: 'military-awareness',
+  militaryInstallationsLayer: 'military-installations',
+  rocketLaunchesLayer: 'rocket-launches',
+});
+
+/** Capture the ordered application instances and their serialization metadata. */
+export function createLayerCatalog(layers, metadata) {
+  if (!Array.isArray(layers) || !Array.isArray(metadata))
+    throw new TypeError(
+      'Layer instances and serialization metadata are required',
+    );
+  const byId = new Map();
+  for (const layer of layers) {
+    if (typeof layer?.id !== 'string' || !layer.id || byId.has(layer.id))
+      throw new TypeError(`Invalid or duplicate catalog layer: ${layer?.id}`);
+    byId.set(layer.id, layer);
+  }
+  const ids = new Set();
+  for (const entry of metadata) {
+    if (!byId.has(entry?.id) || ids.has(entry.id))
+      throw new TypeError(
+        `Unmatched or duplicate catalog metadata: ${entry?.id}`,
+      );
+    ids.add(entry.id);
+  }
+  if (ids.size !== byId.size)
+    throw new TypeError('Catalog metadata is incomplete');
+  return Object.freeze({
+    layers: Object.freeze([...layers]),
+    metadata: Object.freeze(
+      metadata.map((entry) => Object.freeze({ ...entry })),
+    ),
+    get: (id) => byId.get(id),
+  });
+}
+
+/** Bind the current control surface to the exact instances registered by the app. */
+export function catalogControlServices(catalog) {
+  if (!catalog?.get)
+    throw new TypeError('An application layer catalog is required');
+  return Object.fromEntries(
+    Object.entries(CONTROL_LAYER_IDS).map(([role, id]) => {
+      const layer = catalog.get(id);
+      if (!layer)
+        throw new TypeError(`Control layer missing from catalog: ${id}`);
+      return [role, layer];
+    }),
+  );
+}