Explain empty imagery configuration in Street Level controls

src/ui/streetLevelPresentation.js

@@ -125,6 +125,7 @@ function presentViewer(state) {
 }
 
 function presentMeta(state) {
+  if (state.providers.length === 0) return state.coverage.hint || '';
   if (!state.enabled) return 'Switch a provider on to draw its coverage.';
   if (state.sequence.selectedId)
     return state.sequence.loading
@@ -147,7 +148,7 @@ export function presentStreetLevelPanel(state, { now = Date.now() } = {}) {
     enabled,
     keyRequired,
     status: presentStatus(state),
-    controlsDisabled: keyRequired,
+    controlsDisabled: keyRequired || state.providers.length === 0,
     providers: presentProviders(state),
     error: keyMissing
       ? null

src/ui/streetLevelPresentation.test.mjs

@@ -9,6 +9,23 @@ import { providerSnapshot } from '../testSupport/streetLevelFakes.mjs';
 
 const provider = providerSnapshot;
 
+test('an empty composition explains unavailable imagery even while disabled', () => {
+  for (const enabled of [false, true]) {
+    const view = presentStreetLevelPanel(
+      snapshot({
+        enabled,
+        providers: [],
+        coverage: { hint: 'No street-level imagery providers configured' },
+        legend: [],
+      }),
+    );
+    assert.equal(view.controlsDisabled, true);
+    assert.equal(view.keyRequired, false);
+    assert.deepEqual(view.providers, []);
+    assert.equal(view.meta, 'No street-level imagery providers configured');
+  }
+});
+
 function snapshot(overrides = {}) {
   const base = {
     enabled: false,