Merge pull request #983 from bilawalsidhu/feat/optional-catalog-sources

Make catalog feeds optional and configurable at startup

CHANGELOG.md

@@ -1,5 +1,15 @@
 # Changelog
 
+- Catalog source availability no longer modifies layer objects; unavailable
+  tooltips use layer display names.
+
+- Street Level with no providers uses the shared unavailable state and refuses
+  activation before initialization, while keeping its layer identity visible.
+
+- Application source configuration accepts replacements and explicit removal.
+  Missing catalog feeds leave their layers unavailable without blocking startup
+  or making fallback requests; malformed supplied feeds remain configuration errors.
+
 - Street Level providers are optional in application composition. Omitting a
   Mapillary source no longer prevents startup; callers can inject a different
   provider list or an empty list without changing layer identities or share links.

docs/CURRENT-STATE.md

@@ -1,5 +1,18 @@
 # God's Eye View Current State
 
+Catalog source contracts and their consuming layers are declared in
+`src/app/sourceComposition.js`. Omitted or null acquisition sources preserve layer
+registration and serialization, report unavailable, and are refused by the existing
+visibility lifecycle before initialization. Availability is held in an explicit
+catalog lookup supplied to the lifecycle, without modifying layer instances;
+unavailable reasons use the layer display name. Invalid supplied methods still fail
+construction. `createStandaloneApplication` and `createStandaloneCatalog` accept
+`sources` overrides; unspecified entries retain
+standalone defaults, and null entries explicitly remove a source. Street Level
+continues to accept an explicit provider list. An empty Street Level provider
+list uses the same unavailable lifecycle and disabled layer toggle. Directions and Recent Imagery
+acquisition are still selected by their application constructors.
+
 Application catalog composition accepts an optional `streetLevelProviders` list.
 An explicit list replaces the default Mapillary provider; an empty list removes
 all imagery providers. Without that option, Mapillary is registered only when

scripts/package-boundaries.json

@@ -1434,6 +1434,7 @@
       "src/annotations/worldAnnotationRenderer.js",
       "src/app/catalog.js",
       "src/app/constructCatalog.js",
+      "src/app/sourceComposition.js",
       "src/app/controls.js",
       "src/app/data.js",
       "src/app/errors.js",
@@ -2222,6 +2223,7 @@
       "src/annotations/resolver.js",
       "src/app/catalog.js",
       "src/app/constructCatalog.js",
+      "src/app/sourceComposition.js",
       "src/layers/wind/index.js",
       "src/layers/wind/model.js",
       "src/layers/wind/fields.js",

src/app/catalog.test.mjs

@@ -65,13 +65,28 @@ test('data setup seals the caller catalog before controls can restore and drains
         },
       },
     },
-    catalog: createLayerCatalog(layers, metadata(layers)),
+    catalog: {
+      ...createLayerCatalog(layers, metadata(layers)),
+      getSourceAvailability: (id) =>
+        id === 'one'
+          ? {
+              available: false,
+              reason: 'One: data source not configured',
+            }
+          : undefined,
+    },
     defer: (release) => releases.push(release),
     onData: (manager) => {
       observed = manager;
     },
   });
   assert.equal(observed, dataManager);
+  assert.equal(await dataManager.setEnabled('one', true), false);
+  assert.equal(dataManager.layers.get('one').initialized, false);
+  assert.equal(
+    dataManager.getAll().find(({ id }) => id === 'one').stats.error,
+    'One: data source not configured',
+  );
   assert.deepEqual(attached, [['one', 'two']]);
   assert.deepEqual([...dataManager.layers.keys()], ['one', 'two']);
   assert.throws(() => dataManager.register({ id: 'late' }), /finalized/);

src/app/constructCatalog.js

@@ -1,3 +1,4 @@
+import { resolveCatalogSources } from './sourceComposition.js';
 import { createWeatherClock } from '../layers/weather/clock.js';
 import { createWeatherLayer } from '../layers/weather/index.js';
 import { createCyclonesLayer } from '../layers/cyclones/index.js';
@@ -31,33 +32,6 @@ import { localGeoJsonServices } from './localGeojsonServices.js';
 import { createBhoteKoshiEventLayer } from '../data/bhoteKoshiEvent.js';
 import { createBhoteKoshiLocatorLayer } from '../data/bhoteKoshiLocator.js';
 
-const SOURCE_METHODS = Object.freeze({
-  flights: ['getSnapshot'],
-  military: ['getSnapshot'],
-  vessels: ['getSnapshot'],
-  cctv: ['getCatalog', 'getHealth', 'getFrameUrl', 'getMediaUrl'],
-  radio: ['getDirectory', 'recordClick'],
-  traffic: [
-    'requestRoads',
-    'getStatus',
-    'fetchFlowForBounds',
-    'getFlowSessionStats',
-    'resetFlowTileCache',
-  ],
-  bikeshare: ['getStations'],
-  installations: ['getMappedSites', 'searchNearby'],
-  satellites: ['readGroup'],
-  launches: ['getLaunches', 'getActiveTle'],
-  alpr: ['fetch'],
-  firms: ['getSnapshot'],
-  wind: ['getSnapshot'],
-  weather: ['getSnapshot'],
-  cyclones: ['getSnapshot'],
-  earthquakes: ['getSnapshot'],
-  'fire-perimeters': ['getSnapshot'],
-  cables: ['fetch'],
-});
-
 /**
  * Hardware-local layers are registered like any other but never enter share
  * links or stored layer state: another browser cannot have this receiver.
@@ -92,12 +66,8 @@ export function createApplicationCatalog({
   if (!surface?.groundFloor || !surface?.terrain)
     throw new TypeError('Application surface services are required');
 
-  for (const [name, methods] of Object.entries(SOURCE_METHODS)) {
-    if (
-      methods.some((method) => typeof sources?.[name]?.[method] !== 'function')
-    )
-      throw new TypeError(`Invalid catalog source: ${name}`);
-  }
+  const sourceComposition = resolveCatalogSources(sources);
+  sources = sourceComposition.sources;
   const militaryRegistry = createMilitaryRegistry();
   const weatherClock = createWeatherClock();
   const dispose = () => {
@@ -107,7 +77,8 @@ export function createApplicationCatalog({
   };
   signal.addEventListener('abort', dispose, { once: true });
   try {
-    militaryRegistry.configureSource(sources.military, { signal });
+    if (sourceComposition.isConfigured('military'))
+      militaryRegistry.configureSource(sources.military, { signal });
     const flights = createApplicationFlights({
       surface,
       source: sources.flights,
@@ -204,6 +175,9 @@ export function createApplicationCatalog({
     );
     return Object.freeze({
       ...catalog,
+      getSourceAvailability: sourceComposition.createAvailabilityLookup(
+        catalog.layers,
+      ),
       militaryRegistry,
       surface,
       weatherClock,

src/app/constructCatalog.test.mjs

@@ -117,7 +117,7 @@ test('invalid or already cancelled construction fails before classification can
   assert.throws(
     () =>
       createApplicationCatalog({
-        sources: {},
+        sources: { flights: {} },
         signal: lifetime.signal,
         surface: fixtureSurface(lifetime.signal),
       }),

src/app/data.js

@@ -13,6 +13,7 @@ export function createApplicationData({
   // Initialize data layer manager
   const dataManager = new LayerLifecycle(viewer, {
     allowQaRegistration,
+    getSourceAvailability: catalog?.getSourceAvailability,
   });
   defer(async () => {
     await dataManager.destroyAll();

src/app/sourceComposition.js

@@ -0,0 +1,108 @@
+const contract = (layers, methods) =>
+  Object.freeze({
+    layers: Object.freeze(layers),
+    methods: Object.freeze(methods),
+  });
+
+/** Acquisition contracts and their consumers; records remain family-specific. */
+export const CATALOG_SOURCE_CONTRACTS = Object.freeze({
+  flights: contract(['flights'], ['getSnapshot']),
+  military: contract(['military'], ['getSnapshot']),
+  vessels: contract(['ais-live-vessels'], ['getSnapshot']),
+  cctv: contract(
+    ['cctv'],
+    ['getCatalog', 'getHealth', 'getFrameUrl', 'getMediaUrl'],
+  ),
+  radio: contract(['radio'], ['getDirectory', 'recordClick']),
+  traffic: contract(
+    ['traffic'],
+    [
+      'requestRoads',
+      'getStatus',
+      'fetchFlowForBounds',
+      'getFlowSessionStats',
+      'resetFlowTileCache',
+    ],
+  ),
+  bikeshare: contract(['bikeshare'], ['getStations']),
+  installations: contract(
+    ['military-installations'],
+    ['getMappedSites', 'searchNearby'],
+  ),
+  satellites: contract(['satellites'], ['readGroup']),
+  launches: contract(['rocket-launches'], ['getLaunches', 'getActiveTle']),
+  alpr: contract(['alpr-cameras'], ['fetch']),
+  firms: contract(['local-firms'], ['getSnapshot']),
+  wind: contract(['wind'], ['getSnapshot']),
+  weather: contract(
+    ['weather-radar', 'weather-satellite', 'weather-lightning'],
+    ['getSnapshot'],
+  ),
+  cyclones: contract(['weather-cyclones'], ['getSnapshot']),
+  earthquakes: contract(['earthquakes'], ['getSnapshot']),
+  'fire-perimeters': contract(['fire-perimeters'], ['getSnapshot']),
+  cables: contract(['telegeography-submarine-cables'], ['fetch']),
+  transit: contract(['transit'], ['requestSnapshot', 'getHistory']),
+});
+
+/** An omitted provider is unavailable, never an authoritative empty dataset. */
+export class SourceUnavailableError extends Error {
+  constructor(name) {
+    super(`Data source not configured: ${name}`);
+    this.name = 'SourceUnavailableError';
+    this.code = 'unavailable';
+    this.unavailable = true;
+    this.retryable = false;
+  }
+}
+
+/** Validate supplied contracts and keep omitted sources inert during construction. */
+export function resolveCatalogSources(supplied = {}) {
+  if (!supplied || typeof supplied !== 'object' || Array.isArray(supplied))
+    throw new TypeError('Catalog sources must be an object');
+  const sources = { ...supplied };
+  const missing = new Set();
+  for (const [name, { methods }] of Object.entries(CATALOG_SOURCE_CONTRACTS)) {
+    const source = sources[name];
+    if (source == null) {
+      missing.add(name);
+      const unavailable = () => {
+        throw new SourceUnavailableError(name);
+      };
+      sources[name] = Object.freeze({
+        label: name,
+        ...Object.fromEntries(methods.map((method) => [method, unavailable])),
+      });
+    } else if (methods.some((method) => typeof source[method] !== 'function')) {
+      throw new TypeError(`Invalid catalog source: ${name}`);
+    }
+  }
+  return {
+    sources,
+    isConfigured: (name) => !missing.has(name),
+    createAvailabilityLookup(layers) {
+      const byId = new Map(layers.map((layer) => [layer.id, layer]));
+      const availability = new Map();
+      for (const [name, { layers: ids }] of Object.entries(
+        CATALOG_SOURCE_CONTRACTS,
+      )) {
+        for (const id of ids) {
+          const layer = byId.get(id);
+          if (!layer) throw new Error(`Missing source consumer: ${id}`);
+          availability.set(
+            id,
+            Object.freeze({
+              available: !missing.has(name),
+              source: name,
+              reason: missing.has(name)
+                ? `${layer.name || id}: data source not configured`
+                : null,
+            }),
+          );
+        }
+      }
+      return (id) =>
+        availability.get(id) ?? byId.get(id)?.getSourceAvailability?.();
+    },
+  };
+}

src/app/sourceComposition.test.mjs

@@ -0,0 +1,156 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import {
+  resolveCatalogSources,
+  CATALOG_SOURCE_CONTRACTS,
+} from './sourceComposition.js';
+import { createApplicationCatalog } from './constructCatalog.js';
+import { createSurfaceServices } from './surfaceServices.js';
+import { createStandaloneLayerSources } from '../standalone/layerSources.js';
+import { LayerLifecycle } from '../data/lifecycle.js';
+
+function catalog(sources, t) {
+  const lifetime = new AbortController();
+  t.after(() => lifetime.abort());
+  return createApplicationCatalog({
+    sources,
+    signal: lifetime.signal,
+    surface: createSurfaceServices({
+      terrainSource: { getHeights: async () => [] },
+      signal: lifetime.signal,
+      eventTarget: null,
+    }),
+  });
+}
+
+test('every acquisition source can be omitted without losing catalog membership', (t) => {
+  const baseline = catalog(createStandaloneLayerSources(), t);
+  for (const name of Object.keys(CATALOG_SOURCE_CONTRACTS)) {
+    const sources = createStandaloneLayerSources({ [name]: null });
+    const actual = catalog(sources, t);
+    assert.deepEqual(actual.metadata, baseline.metadata, name);
+    for (const id of CATALOG_SOURCE_CONTRACTS[name].layers) {
+      assert.equal(actual.getSourceAvailability(id).available, false, id);
+    }
+  }
+});
+
+test('all acquisition sources may be absent, and enable fails before initializing or fetching', async (t) => {
+  const actual = catalog({}, t);
+  assert.equal(actual.layers.length, 30);
+  const manager = new LayerLifecycle(
+    {},
+    { getSourceAvailability: actual.getSourceAvailability },
+  );
+  for (const layer of actual.layers) manager.register(layer);
+  for (const { layers: ids } of Object.values(CATALOG_SOURCE_CONTRACTS)) {
+    for (const id of ids) {
+      assert.equal(await manager.setEnabled(id, true), false, id);
+      assert.equal(manager.layers.get(id).initialized, false, id);
+      const row = manager.getAll().find((entry) => entry.id === id);
+      assert.equal(row.enabled, false);
+      assert.equal(row.stats.status, 'unavailable');
+      assert.match(row.stats.error, /data source not configured/);
+    }
+  }
+});
+
+test('configured sources retain identity; invalid implementations never become unavailable silently', () => {
+  const source = { getSnapshot: async () => [] };
+  assert.equal(
+    resolveCatalogSources({ earthquakes: source }).sources.earthquakes,
+    source,
+  );
+  for (const name of Object.keys(CATALOG_SOURCE_CONTRACTS)) {
+    assert.throws(
+      () => resolveCatalogSources({ [name]: {} }),
+      /Invalid catalog source/,
+    );
+  }
+  const missing = resolveCatalogSources({}).sources.earthquakes;
+  assert.throws(() => missing.getSnapshot(), { code: 'unavailable' });
+});
+
+test('standalone defaults allow exact replacements and explicit removal, and reject typos', () => {
+  const source = { getSnapshot: async () => [] };
+  const sources = createStandaloneLayerSources({
+    flights: source,
+    military: null,
+  });
+  assert.equal(sources.flights, source);
+  assert.equal(sources.military, null);
+  assert.equal(typeof sources.cctv.getCatalog, 'function');
+  assert.throws(
+    () => createStandaloneLayerSources({ fligts: source }),
+    /Unknown source/,
+  );
+});
+
+test('empty Street Level uses the shared unavailable lifecycle without initialization', async (t) => {
+  const actual = catalog({}, t);
+  const manager = new LayerLifecycle(
+    {},
+    { getSourceAvailability: actual.getSourceAvailability },
+  );
+  manager.register(actual.get('street-level'));
+  assert.equal(await manager.setEnabled('street-level', true), false);
+  assert.equal(manager.layers.get('street-level').initialized, false);
+  const row = manager.getAll()[0];
+  assert.equal(row.stats.status, 'unavailable');
+  assert.equal(row.stats.error, 'No street-level imagery providers configured');
+  assert.equal(await manager.setEnabled('street-level', false), true);
+  const configured = catalog(createStandaloneLayerSources(), t);
+  assert.equal(
+    configured.get('street-level').getSourceAvailability().available,
+    true,
+  );
+});
+
+test('availability lookup accepts frozen layers and uses their display names', () => {
+  const composition = resolveCatalogSources({});
+  const layers = Object.values(CATALOG_SOURCE_CONTRACTS)
+    .flatMap(({ layers }) => layers)
+    .map((id) =>
+      Object.freeze({
+        id,
+        name: id === 'fire-perimeters' ? 'Fire perimeters' : id,
+      }),
+    );
+  const lookup = composition.createAvailabilityLookup(layers);
+  assert.equal(
+    lookup('fire-perimeters').reason,
+    'Fire perimeters: data source not configured',
+  );
+  assert.equal(Object.hasOwn(layers[0], 'getSourceAvailability'), false);
+  const manager = new LayerLifecycle({}, { getSourceAvailability: lookup });
+  manager.register(layers.find(({ id }) => id === 'fire-perimeters'));
+  assert.equal(
+    manager.getAll()[0].stats.error,
+    'Fire perimeters: data source not configured',
+  );
+});
+
+test('absent military acquisition does not poll, suppress flights, or erase supplied classification', async (t) => {
+  let fetches = 0;
+  t.mock.method(globalThis, 'fetch', async () => {
+    fetches++;
+    throw new Error('Unexpected fallback acquisition');
+  });
+  const actual = catalog(createStandaloneLayerSources({ military: null }), t);
+  const registry = actual.militaryRegistry;
+  assert.equal(actual.getSourceAvailability('flights').available, true);
+  assert.equal(registry.isMilitaryLayerActive(), false);
+  assert.equal(registry.isMilitaryIcao('abc123'), false);
+  registry.registerMilitaryIcaos([' ABC123 ']);
+  await registry.refreshMilitaryRegistryIfStale();
+  assert.equal(registry.isMilitaryIcao('abc123'), true);
+  assert.equal(registry.isMilitaryIcao('def456'), false);
+  const manager = new LayerLifecycle(
+    {},
+    { getSourceAvailability: actual.getSourceAvailability },
+  );
+  manager.register(actual.get('military'));
+  assert.equal(await manager.setEnabled('military', true), false);
+  assert.equal(registry.isMilitaryLayerActive(), false);
+  assert.equal(fetches, 0);
+});

src/data/lifecycle.js

@@ -74,7 +74,11 @@ function refreshFailureFromStats(stats, label) {
  * for real-time data overlays on the CesiumJS globe.
  */
 export class LayerLifecycle {
-  constructor(viewer, { allowQaRegistration = false } = {}) {
+  constructor(
+    viewer,
+    { allowQaRegistration = false, getSourceAvailability } = {},
+  ) {
+    this._catalogSourceAvailability = getSourceAvailability;
     this.viewer = viewer;
     this._activityListeners = new Set();
     this.layers = new Map(); // id → { module, enabled, initialized, intervalId, lifecycleState, lifecycleUncertain }
@@ -228,6 +232,7 @@ export class LayerLifecycle {
 
   _normalizedStats(entry) {
     const moduleStats = this._moduleStats(entry);
+    const availability = this._sourceAvailability(entry.module.id);
     const lifecycleLoading =
       entry.lifecycleState === 'enabling' ||
       entry.lifecycleState === 'disabling';
@@ -235,6 +240,13 @@ export class LayerLifecycle {
       count: 0,
       lastUpdate: null,
       ...moduleStats,
+      ...(availability?.available === false
+        ? {
+            status: 'unavailable',
+            sourceUnavailable: true,
+            error: availability.reason,
+          }
+        : {}),
       loading: lifecycleLoading || moduleStats.loading === true,
       refreshing: entry.refreshing || moduleStats.refreshing === true,
       managerRefreshError: entry.managerRefreshError,
@@ -2282,7 +2294,17 @@ export class LayerLifecycle {
     }
   }
 
+  _sourceAvailability(layerId) {
+    return (
+      this._catalogSourceAvailability?.(layerId) ??
+      this.layers.get(layerId)?.module.getSourceAvailability?.()
+    );
+  }
+
   async _visibilityBlockReason(change) {
+    const availability = this._sourceAvailability(change.layerId);
+    if (change.enabled && availability?.available === false)
+      return availability.reason || 'Data source unavailable';
     for (const callback of this._visibilityGuards) {
       try {
         const result = await callback(change);

src/layers/streetLevel/index.js

@@ -333,6 +333,16 @@ export function createStreetLevelLayer({
     requiresKeyId: requiresKeyIdFor(definitionsFrozen),
     /** Registered providers, in chip order. */
     providerIds: definitionsFrozen.map((def) => def.id),
+    getSourceAvailability() {
+      const available = definitionsFrozen.length > 0;
+      return {
+        available,
+        source: STREET_LEVEL_LAYER_ID,
+        reason: available
+          ? null
+          : 'No street-level imagery providers configured',
+      };
+    },
 
     init(viewer) {
       if (state.initialized)

src/standalone/application.js

@@ -17,6 +17,8 @@ export function createStandaloneApplication({
   cesiumToken,
   geospatial = {},
   voice = {},
+  sources = {},
+  streetLevelProviders,
   allowQaRegistration = false,
 }) {
   if (constructed)
@@ -47,6 +49,8 @@ export function createStandaloneApplication({
         loaderStatus,
       });
       catalog = createStandaloneCatalog({
+        sources,
+        streetLevelProviders,
         nepalBoundaryResolver: (signal) =>
           scene.operations.annotationResolver.resolveRegionRingForQuery(
             'Nepal',

src/standalone/catalog.js

@@ -7,6 +7,8 @@ export { createStandaloneReferenceSources } from './layerSources.js';
 /** Create fresh layer instances using the existing standalone source choices. */
 export function createStandaloneCatalog({
   nepalBoundaryResolver,
+  sources = {},
+  streetLevelProviders,
   signal = new AbortController().signal,
   surface = createSurfaceServices({
     terrainSource: createApplicationRequestServices().terrain,
@@ -16,7 +18,8 @@ export function createStandaloneCatalog({
   return createApplicationCatalog({
     nepalBoundaryResolver,
     surface,
-    sources: createStandaloneLayerSources(),
+    sources: createStandaloneLayerSources(sources),
+    streetLevelProviders,
     signal,
     vesselOptions: {
       maxRows: import.meta.env?.VITE_AIS_LIVE_MAX_ROWS,

src/standalone/layerSources.js

@@ -22,9 +22,11 @@ import { createReferenceSources } from '../sources/reference.js';
 export { createReferenceSources as createStandaloneReferenceSources } from '../sources/reference.js';
 
 /** Select standalone providers without starting their acquisition. */
-export function createStandaloneLayerSources() {
+export function createStandaloneLayerSources(overrides = {}) {
+  if (!overrides || typeof overrides !== 'object' || Array.isArray(overrides))
+    throw new TypeError('Source overrides must be an object');
   const mapTiles = createOpenFreeMapSource();
-  return {
+  const defaults = {
     ...createReferenceSources(),
     flights: createFlightSource(),
     military: createMilitarySource(),
@@ -51,4 +53,9 @@ export function createStandaloneLayerSources() {
       token: import.meta.env?.MAPILLARY_CLIENT_TOKEN || '',
     }),
   };
+  for (const name of Object.keys(overrides)) {
+    if (!Object.hasOwn(defaults, name))
+      throw new TypeError(`Unknown source: ${name}`);
+  }
+  return { ...defaults, ...overrides };
 }

src/ui/layerPanel.js

@@ -588,7 +588,12 @@ export class LayerPanel {
   }
 
   _syncToggleButton(button, layer) {
-    const feedState = layer.enabled ? layerFeedState(layer.stats) : 'off';
+    const unavailable = layer.stats?.sourceUnavailable === true;
+    const feedState = unavailable
+      ? 'unavailable'
+      : layer.enabled
+        ? layerFeedState(layer.stats)
+        : 'off';
     const transitioning =
       layer.lifecycleState === 'enabling' ||
       layer.lifecycleState === 'disabling';
@@ -601,7 +606,7 @@ export class LayerPanel {
     for (const state of Object.keys(FEED_STATE_LABELS)) {
       button.classList.toggle(
         `feed-${state}`,
-        layer.enabled && !uncertain && feedState === state,
+        (layer.enabled || unavailable) && !uncertain && feedState === state,
       );
     }
     button.dataset.feedState = transitioning
@@ -613,16 +618,21 @@ export class LayerPanel {
     // click guard above prevents repeat activation without the focus loss caused
     // by native `disabled`.
     button.disabled = false;
-    button.setAttribute('aria-disabled', String(transitioning));
+    button.setAttribute(
+      'aria-disabled',
+      String(transitioning || (unavailable && !layer.enabled)),
+    );
     button.setAttribute('aria-busy', String(transitioning));
     button.textContent = transitioning
       ? layer.lifecycleState.toUpperCase()
       : uncertain
         ? 'UNCERTAIN'
-        : layer.enabled
+        : layer.enabled || unavailable
           ? FEED_STATE_LABELS[feedState]
           : 'OFF';
-    const keyGuidance = layerKeyRequirementTooltip(layer);
+    const keyGuidance = unavailable
+      ? String(layer.stats.error || 'Data source unavailable')
+      : layerKeyRequirementTooltip(layer);
     // Name the missing key on the control itself: a row reading KEY REQUIRED
     // without saying WHICH key leaves a dead control and no next step. Empty
     // when the layer needs no key, or already has one.

src/ui/layerPanel.test.mjs

@@ -228,3 +228,33 @@ test('the Recent Imagery readout mounts in its rail body like the weather readou
     globalThis.document = previousDocument;
   }
 });
+
+test('an omitted source is visibly unavailable and cannot be toggled on', async () => {
+  const { LayerPanel } = await import('./layerPanel.js');
+  const attrs = new Map();
+  const button = {
+    classList: { toggle() {} },
+    dataset: {},
+    setAttribute: (key, value) => attrs.set(key, value),
+  };
+  const layer = {
+    id: 'flights',
+    name: 'Flights',
+    enabled: false,
+    stats: {
+      sourceUnavailable: true,
+      status: 'unavailable',
+      error: 'Data source not configured: flights',
+    },
+  };
+  LayerPanel.prototype._syncToggleButton(button, layer);
+  assert.equal(button.textContent, 'UNAVAILABLE');
+  assert.equal(attrs.get('aria-disabled'), 'true');
+  assert.match(button.title, /not configured/);
+  LayerPanel.prototype._syncToggleButton(button, { ...layer, enabled: true });
+  assert.equal(
+    attrs.get('aria-disabled'),
+    'false',
+    'an active layer can always be switched off',
+  );
+});