feat(street-level): OPEN STREET VIEW, and Street View only on Google 3D

- OPEN STREET VIEW in the PROVIDERS row opens Street View's nearest
  panorama at the ground under the middle of the screen, without moving
  the camera: Street View no longer needs a pointer. It is disabled (and
  says so) until the camera is at street zoom.
- Off the Google 3D map Street View does not appear at all: no chip,
  legend swatch, globe credit, layer source or button, and Google's script
  is not loaded (the viewer has no prewarm; the script loads on first use).
  The share option keeps the user's choice for when Google 3D returns.
- A ground click measures the camera height at the click rather than
  reading the cached flag.
- A chip without a usable key explains it instead of lighting; it darkens
  beside a lit chip, and the other chips keep switching, so a refused
  Street View key cannot lock Mapillary out.
- The gate checks that nothing of Street View shows off Google 3D even when
  a share link switches it on, presses OPEN STREET VIEW on Google 3D, and
  asserts that each chip it switches really switched.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

CHANGELOG.md

@@ -66,7 +66,8 @@
 - Street Level: Google Street View is the second provider. On the Google 3D
   map (Google's terms keep it off other maps), light its chip (off by
   default: every panorama is billed to the Google Maps key, which needs the
-  Maps JavaScript API) and click a street to open Google's own panorama in
+  Maps JavaScript API) and click a street, or press OPEN STREET VIEW, to
+  open Google's own panorama in
   the panel, with its arrows, the address and month in the caption, a link
   to Google Maps and FOLLOW. Share links carry it as `g`.
 

README.md

@@ -338,7 +338,7 @@ _The Space Missions layer replaying a Falcon 9 ascent — labeled `RECONSTRUCTED
 
 **Setup.** At [mapillary.com/dashboard/developers](https://www.mapillary.com/dashboard/developers), register an application with **Read** access and copy its **Client Token** (`MLY|…`). Paste it into **POWER UP → Mapillary**, or set `MAPILLARY_CLIENT_TOKEN` in `.env` and restart. Without it the panel reads **KEY REQUIRED**. **Google Street View** uses `GOOGLE_MAPS_API_KEY` with the **Maps JavaScript API** enabled for it in Google Cloud; its chip starts off, since every panorama is billed to the key.
 
-**Use.** Turn on **Street Level** under DATA LAYERS → Cameras, or with the pill in the STREET LEVEL panel header. Each provider has a chip in its own colour (Mapillary green). The **IMAGERY** (ALL / 360° / FLAT) and **SINCE** filters apply to every provider. Click a coverage line for its image cones and a cone to open the photo. With **STREET VIEW** lit on the **Google 3D** map (Google's terms keep Street View off other maps), click a street from below 3 km to open Google's panorama there, and step along its arrows. Above the photo: **EXPAND**, **FIT / FILL** (Mapillary), and **FOLLOW** (the globe camera follows the photo's view; Google 3D map only). The caption links to the image on the provider's site, and the globe credits each provider that is on ("© Mapillary contributors, CC BY-SA 4.0", "Street View imagery © Google").
+**Use.** Turn on **Street Level** under DATA LAYERS → Cameras, or with the pill in the STREET LEVEL panel header. Each provider has a chip in its own colour (Mapillary green). The **IMAGERY** (ALL / 360° / FLAT) and **SINCE** filters apply to every provider. Click a coverage line for its image cones and a cone to open the photo. On the **Google 3D** map (Google's terms keep Street View off other maps, where it does not appear), light **STREET VIEW** and click a street from below 3 km, or press **OPEN STREET VIEW** for the view centre, to open Google's panorama there; step along its arrows. Above the photo: **EXPAND**, **FIT / FILL** (Mapillary), and **FOLLOW** (the globe camera follows the photo's view; Google 3D map only). The caption links to the image on the provider's site, and the globe credits each provider that is on ("© Mapillary contributors, CC BY-SA 4.0", "Street View imagery © Google").
 
 Drag the panel header to float the panel, and resize it from any edge. Double-click the header or collapse it to put it back in the rail. Share links carry the provider switches and filters (`0.m.0` Mapillary off, `0.g.1` Street View on, `0.p.p` panoramas only, `0.s.365` the last year). To add a provider, implement the contract in `src/layers/streetLevel/registry.js` and register it in `src/app/layers/streetLevel.js`.
 

docs/CURRENT-STATE.md

@@ -3060,7 +3060,10 @@ ground level. Framing a photo ignores mesh samples far below the bare earth
 (unloaded tiles).
 
 The header pill is the layer switch. With one provider its chip is a layer
-switch too; with several, darkening the last lit chip turns the layer off. The
+switch too; with several, darkening the last lit chip turns the layer off. A
+chip without a usable key explains the key instead of lighting (or of
+switching the layer off as the last lit chip); it still darkens beside a lit
+one, and the other chips keep switching. The
 viewer sits under the header with EXPAND, FIT/FILL, FOLLOW and close above the
 image. FOLLOW needs the Google 3D map stack (`attachMapStackController`) and
 stops when the stack changes. Camera moves go through the application's
@@ -3090,14 +3093,18 @@ on first use (`mapsLoader.js`, CSP `script-src https://maps.googleapis.com`).
 Its chip starts off (`defaultOn: false`, option default `g` off) because every
 panorama load is billed to the key. Google's terms forbid Street View beside
 non-Google maps, so the provider declares `requiresMapStack: 'photoreal'`:
-off Google 3D its chip is dashed with the reason, lookups and opens skip it,
-and leaving Google 3D closes its panorama. Google offers no coverage layer
+off Google 3D it does not appear at all (no chip, legend swatch, globe
+credit, layer source or button, and Google's script is not loaded), lookups
+and opens skip it, and leaving Google 3D closes its panorama; the share
+option keeps the user's choice for when Google 3D returns. Google offers no coverage layer
 for other maps, so it draws none: with it on, a click on the map itself
 (`scenePick.isSurfacePick`: nothing picked or Google 3D tile content, so a
 Mapillary line under the pointer wins; no tool holding the pointer; camera
 below 3 km) opens its nearest Google-collected outdoor panorama within 50 m
 and leaves the camera where it is (`groundClick.js`). Higher up the hint
-says to zoom in. The viewer is Google's `StreetViewPanorama` in its own
+says to zoom in. **OPEN STREET VIEW** in the PROVIDERS row (`#sl-nearest-btn`)
+does the same at the view centre, so Street View needs no pointer; it is
+disabled until the camera is at street zoom. The viewer is Google's `StreetViewPanorama` in its own
 element in the viewer host, without Google's fullscreen, close and address
 controls (the address goes in the caption); a pose goes out at once and
 again when the panorama's month, photographer and address arrive (one
@@ -3105,8 +3112,9 @@ lookup per panorama per session, seeded by the nearest lookup). A key
 Google refuses (`gm_authFailure`: the API not enabled, a referrer it does
 not allow, billing off) reads KEY REJECTED and fails a pending open at
 once; a lookup or open Google never answers fails after 10 or 20 s. In CI
-(no Google key, no Google 3D) only the chip and share-link step runs; the
-click step skips as `no Google key`.
+(no Google key, no Google 3D) the gate checks that nothing of Street View
+shows off Google 3D, even switched on by a share link; the click and button
+step skips as `no Google key`.
 
 Street Level has two browser gates. `npm run qa:street-level -- --url <server>`
 runs against real Mapillary and needs `MAPILLARY_CLIENT_TOKEN`. `npm run

scripts/qa-street-level.mjs

@@ -653,7 +653,20 @@ async function main() {
             ),
           ].map((chip) => chip.dataset.chipId),
         );
-        assert.deepEqual(chips, EXPECTED_PROVIDERS);
+        // Every registered provider usable on this map, in order (Street View
+        // only on Google 3D).
+        const listed = await page.evaluate(() =>
+          window.__godsEyeView.dataManager.layers
+            .get('street-level')
+            .module.getUIState()
+            .providers.map((provider) => provider.id),
+        );
+        assert.deepEqual(chips, listed);
+        assert.deepEqual(
+          EXPECTED_PROVIDERS.filter((id) => listed.includes(id)),
+          listed,
+        );
+        assert.ok(listed.includes('mapillary'));
         // One swatch per switched-on source plus "Selected" (Street View
         // starts off); each chip wears its colour.
         const legend = await page.evaluate(() => ({
@@ -1733,35 +1746,57 @@ async function main() {
         Boolean(window.__GOOGLE_MAPS_API_KEY__),
       );
       await step(
-        'Street View starts off, lights from its chip, and travels in the share link',
+        'Street View starts off, appears only on the Google 3D map, and travels in the share link',
         async () => {
-          const read = () =>
-            page.$eval(
-              '#sl-provider-chips [data-chip-id="google"]',
-              (node) => ({
-                active: node.classList.contains('active'),
-                className: node.className,
-                title: node.title,
-                color: node.style.getPropertyValue('--chip-color'),
-              }),
-            );
-          const off = await read();
+          const module = () =>
+            window.__godsEyeView.dataManager.layers.get('street-level').module;
           assert.equal(
-            off.active,
+            await page.evaluate(`(${module})().getParams().google`),
             false,
             'off until lit: panoramas are billed',
           );
-          assert.equal(off.color, '#4285f4');
-          await clickPanelControl(page, googleChip);
-          await uiUntil(
-            (u) => u.providers.find((p) => p.id === 'google')?.on === true,
+          const setStreetView = (on) =>
+            page.evaluate(
+              (value) =>
+                window.__godsEyeView.dataManager.setLayerParams(
+                  'street-level',
+                  { google: value },
+                  { origin: 'user' },
+                ),
+              on,
+            );
+          const shown = () =>
+            page.evaluate(() => ({
+              chip: Boolean(
+                document.querySelector(
+                  '#sl-provider-chips [data-chip-id="google"]',
+                ),
+              ),
+              legend: [...document.querySelectorAll('#sl-legend li')].some(
+                (item) => /Street View/.test(item.textContent),
+              ),
+              credit: document.body.innerHTML.includes('Street View imagery'),
+              button: !document.getElementById('sl-nearest-btn').hidden,
+            }));
+          const original = await stacks.active();
+          // Off Google 3D (CI's only map) nothing of Street View shows, even
+          // switched on: Google's terms keep it off other maps.
+          if (original === 'photoreal') await stacks.set('esri-imagery');
+          await setStreetView(true);
+          await uiUntil((u) => u.providers.every((p) => p.id !== 'google'));
+          assert.ok(
+            await settle(
+              page,
+              () => !document.body.innerHTML.includes('Street View imagery'),
+            ),
+            'no Google credit on another map',
           );
-          const lit = await read();
-          if (googleKey) assert.match(lit.className, /chip-active/);
-          else {
-            assert.match(lit.className, /chip-error/, 'no key: an error chip');
-            assert.match(lit.title, /GOOGLE_MAPS_API_KEY/);
-          }
+          assert.deepEqual(await shown(), {
+            chip: false,
+            legend: false,
+            credit: false,
+            button: false,
+          });
           const option = `${STREET_LEVEL_TOKEN}.g.1`;
           assert.ok(
             await settle(
@@ -1772,13 +1807,34 @@ async function main() {
                   .includes(token),
               option,
             ),
-            `the share link carries ${option}`,
+            `the share link keeps the choice: ${option}`,
           );
-          assert.ok((await ui()).coverage.count > 0, 'Mapillary still draws');
-          // Leave it off, so later steps run the same with and without a key.
-          await clickPanelControl(page, googleChip);
+          if (await stacks.photoreal()) {
+            await stacks.set('photoreal');
+            await uiUntil((u) => u.providers.some((p) => p.id === 'google'));
+            const chipNow = await page.$eval(googleChip, (node) => ({
+              className: node.className,
+              title: node.title,
+              color: node.style.getPropertyValue('--chip-color'),
+            }));
+            assert.equal(chipNow.color, '#4285f4');
+            if (googleKey) assert.match(chipNow.className, /chip-active/);
+            else {
+              assert.match(chipNow.className, /chip-error/);
+              assert.match(chipNow.title, /GOOGLE_MAPS_API_KEY/);
+            }
+            assert.ok(
+              await settle(page, () =>
+                document.body.innerHTML.includes('Street View imagery'),
+              ),
+              'the Google credit shows on Google 3D',
+            );
+          }
+          // Back off, as the next steps expect.
+          await setStreetView(false);
+          await stacks.set(original);
           await uiUntil(
-            (u) => u.providers.find((p) => p.id === 'google')?.on === false,
+            (u) => u.providers.find((p) => p.id === 'google')?.on !== true,
           );
         },
       );
@@ -1799,10 +1855,13 @@ async function main() {
             const now = (await ui()).providers.find((p) => p.id === id)?.on;
             if (now === on) return;
             await clickPanelControl(page, selector);
-            await uiUntil(
-              (u, want) =>
-                u.providers.find((p) => p.id === want.id)?.on === want.on,
-              { id, on },
+            assert.ok(
+              await uiUntil(
+                (u, want) =>
+                  u.providers.find((p) => p.id === want.id)?.on === want.on,
+                { id, on },
+              ),
+              `the ${id} chip switched ${on ? 'on' : 'off'}`,
             );
           };
           await closePhoto();
@@ -1918,6 +1977,21 @@ async function main() {
               ),
               'the pose bearing follows the drag',
             );
+            // The keyboard path: OPEN STREET VIEW at the view centre.
+            await closePhoto();
+            await uiUntil((u) => u.street.open === false);
+            await clickPanelControl(page, '#sl-nearest-btn');
+            assert.ok(
+              await uiUntil(
+                (u) =>
+                  u.street.providerId === 'google' &&
+                  Boolean(u.street.imageId) &&
+                  !u.street.loading,
+                null,
+                { timeout: 30_000 },
+              ),
+              'OPEN STREET VIEW opens the panorama at the view centre',
+            );
             // Leaving Google 3D closes the panorama (Google's terms).
             await stacks.set('esri-imagery');
             assert.ok(

src/app/layers/streetLevel.test.mjs

@@ -16,12 +16,9 @@ test('each provider starts as its share-link option does, so a fresh page and a
     },
   });
   const options = createDefaultLayerState().options['street-level'];
-  const providers = layer.getUIState().providers;
-  assert.deepEqual(
-    providers.map((p) => p.id),
-    layer.providerIds,
-  );
-  for (const provider of providers)
-    assert.equal(provider.on, options[provider.id], provider.id);
+  // Every registered provider, listed on this map or not.
+  const started = layer.getParams();
+  for (const id of layer.providerIds)
+    assert.equal(started[id], options[id], id);
   assert.equal(options.google, false, 'Street View is billed: off');
 });

src/layers/streetLevel/groundClick.js

@@ -15,15 +15,24 @@ export function groundClickHeightOk(viewer, groundAt) {
  * street zoom opens the nearest image of the active, available providers
  * that have no coverage to click (`groundClick`, Google Street View). The
  * camera stays put: the user chose the spot.
- * @param {{state: object, openNearest: Function, isAvailable: (entry: object) => boolean}} options
+ * The height is measured at the click, not read from the cached flag.
+ * @param {{state: object, openNearest: Function, isAvailable: (entry: object) => boolean, groundAt?: Function}} options
  * @returns {(screenPosition: {x: number, y: number}, picked?: object) => Promise<boolean>|false}
  */
-export function createGroundClick({ state, openNearest, isAvailable }) {
+export function createGroundClick({
+  state,
+  openNearest,
+  isAvailable,
+  groundAt = null,
+}) {
   return function openAtGround(screenPosition, picked) {
     const scenePick = state.services.scenePick;
     if (!state.enabled || !state.viewer || !scenePick?.pickGroundPosition)
       return false;
-    if (!scenePick.isSurfacePick(picked) || !state.groundClickReady)
+    if (
+      !scenePick.isSurfacePick(picked) ||
+      !groundClickHeightOk(state.viewer, groundAt)
+    )
       return false;
     const providerIds = [...state.providers.values()]
       .filter(

src/layers/streetLevel/groundClick.test.mjs

@@ -16,7 +16,7 @@ function harness({
     { id: 'mapillary', groundClick: false },
     { id: 'google', groundClick: true },
   ],
-  ready = true,
+  height = 400,
   enabled = true,
   picked = GROUND,
   ellipsoid = undefined,
@@ -24,7 +24,6 @@ function harness({
   const opened = [];
   const state = {
     enabled,
-    groundClickReady: ready,
     services: { scenePick },
     providers: new Map(
       providers.map(
@@ -42,7 +41,14 @@ function harness({
     ),
     viewer: {
       scene: { pickPositionSupported: true, pickPosition: () => picked },
-      camera: { pickEllipsoid: () => ellipsoid },
+      camera: {
+        pickEllipsoid: () => ellipsoid,
+        positionCartographic: Cesium.Cartographic.fromDegrees(
+          -121.4944,
+          38.5816,
+          height,
+        ),
+      },
     },
   };
   const openAtGround = createGroundClick({
@@ -87,7 +93,7 @@ test('nothing opens over another layer’s object, the sky, from high up, off it
     { picked: { id: { id: 'flight:1' } }, label: 'an entity' },
     { picked: { id: 'cctv:7', primitive: TILESET }, label: 'an id on a tile' },
     { options: { picked: null, ellipsoid: undefined }, label: 'the sky' },
-    { options: { ready: false }, label: 'high up' },
+    { options: { height: 5000 }, label: 'high up' },
     {
       options: {
         providers: [{ id: 'google', groundClick: true, available: false }],

src/layers/streetLevel/index.js

@@ -1,3 +1,4 @@
+import * as Cesium from 'cesium';
 import { createState } from './state.js';
 import { createMarker } from './marker.js';
 import { createCameraFollow } from './cameraFollow.js';
@@ -71,6 +72,7 @@ export function createStreetLevelLayer({
     state,
     openNearest: (point, options) => layer.openNearest(point, options),
     isAvailable: (entry) => providerAvailable(entry),
+    groundAt: parts.groundCaster?.groundAt ?? null,
   });
 
   let notifyQueued = false;
@@ -155,11 +157,23 @@ export function createStreetLevelLayer({
     return !required || mapStack?.getActiveId?.() === required;
   }
 
-  /** Leaving a provider's map stack closes the image it shows. */
+  /**
+   * A provider appears only on its map stack: leaving it closes the image it
+   * shows, releases its viewer and takes its credit off the globe.
+   */
   function syncProviderAvailability() {
     const owner = state.providers.get(state.street.providerId);
     if (state.street.open && owner && !providerAvailable(owner))
       layer.closeViewer();
+    for (const entry of state.providers.values()) {
+      if (!entry.def.requiresMapStack) continue;
+      if (state.enabled && entry.on && providerAvailable(entry))
+        parts.credits.show(state.viewer, entry.def);
+      else {
+        parts.credits.hide(state.viewer, entry.def);
+        parts.viewerHost.unmount(entry.def.id);
+      }
+    }
     notify();
   }
 
@@ -256,9 +270,14 @@ export function createStreetLevelLayer({
   function activate(entry) {
     if (!state.viewer) return;
     entry.instance.activate(state.viewer);
-    parts.credits.show(state.viewer, entry.def);
     if (!entry.status) refreshStatus(entry);
-    whenIdle(() => parts.viewerHost.prewarm([entry]), 1500);
+    // Off its map stack a provider shows nothing: no credit, no viewer load.
+    if (!providerAvailable(entry)) return;
+    parts.credits.show(state.viewer, entry.def);
+    // Checked again when it runs: the map may have changed meanwhile.
+    whenIdle(() => {
+      if (providerAvailable(entry)) parts.viewerHost.prewarm([entry]);
+    }, 1500);
   }
 
   function deactivate(entry) {
@@ -275,6 +294,24 @@ export function createStreetLevelLayer({
     nearestLookup = null;
   }
 
+  /** The ground under the middle of the screen, or null (no scenePick, sky). */
+  function screenCentreGround() {
+    const canvas = state.viewer?.scene?.canvas;
+    const pick = state.services.scenePick?.pickGroundPosition;
+    if (!pick || !canvas?.clientWidth || !canvas?.clientHeight) return null;
+    const position = pick(state.viewer, {
+      x: canvas.clientWidth / 2,
+      y: canvas.clientHeight / 2,
+    });
+    const carto = position && Cesium.Cartographic.fromCartesian(position);
+    return carto
+      ? {
+          lon: Cesium.Math.toDegrees(carto.longitude),
+          lat: Cesium.Math.toDegrees(carto.latitude),
+        }
+      : null;
+  }
+
   /** `frame: false` keeps the camera where it is (the user picked the spot). */
   function openImage(providerId, imageId, { frame = true } = {}) {
     abortNearest();
@@ -317,16 +354,18 @@ export function createStreetLevelLayer({
 
   /** The hint a ground-click provider shows, or the provider's own. */
   function hintFor(entry, stats) {
-    if (!providerAvailable(entry)) return '';
     if (entry.def.groundClick && stats.hint && !state.groundClickReady)
       return `zoom in to a street to open ${entry.def.name}`;
     return stats.hint || '';
   }
 
+  /** Providers usable on this map stack; the others are not shown at all. */
+  const listedEntries = () =>
+    [...state.providers.values()].filter((entry) => providerAvailable(entry));
+
   function providerSnapshots() {
-    return [...state.providers.values()].map((entry) => {
+    return listedEntries().map((entry) => {
       const stats = entry.instance.coverageStats();
-      const available = providerAvailable(entry);
       return {
         id: entry.def.id,
         name: entry.def.name,
@@ -342,8 +381,8 @@ export function createStreetLevelLayer({
         hint: hintFor(entry, stats),
         error: stats.error || null,
         color: entry.def.colors.coverage,
-        /** Why the provider cannot be used right now, or null. */
-        unavailable: available ? null : unavailableReason(entry),
+        /** No coverage to click: it opens where the user points. */
+        groundClick: entry.def.groundClick === true,
       };
     });
   }
@@ -371,6 +410,7 @@ export function createStreetLevelLayer({
     const { host, ...street } = state.street;
     return composeUIState({
       enabled: state.enabled,
+      groundClickReady: state.groundClickReady,
       filter: state.filter,
       providers: providerSnapshots(),
       street,
@@ -383,7 +423,12 @@ export function createStreetLevelLayer({
     id: STREET_LEVEL_LAYER_ID,
     name: 'Street Level',
     icon: '📷',
-    source: definitionsFrozen.map((def) => def.name).join(' · '),
+    /** The sources usable on this map (Street View only on Google 3D). */
+    get source() {
+      return listedEntries()
+        .map((entry) => entry.def.name)
+        .join(' · ');
+    },
     updateInterval: 0,
     statsRefreshInterval: 1000,
     /** The key the switched-on providers share (or null), for the layer row. */
@@ -463,6 +508,7 @@ export function createStreetLevelLayer({
       else if (coverage.loading) loadingLabel = 'loading coverage...';
       else if (coverage.hint && state.enabled) loadingLabel = coverage.hint;
       return {
+        source: layer.source,
         count: coverage.count,
         loading: coverage.loading,
         keyRequired: coverage.keyRequired,
@@ -530,7 +576,13 @@ export function createStreetLevelLayer({
     attachViewerHost(element) {
       parts.viewerHost.attach(element);
       if (element && state.enabled)
-        whenIdle(() => parts.viewerHost.prewarm(activeEntries()), 1500);
+        whenIdle(
+          () =>
+            parts.viewerHost.prewarm(
+              activeEntries().filter((entry) => providerAvailable(entry)),
+            ),
+          1500,
+        );
     },
     setProviderEnabled,
     /** Imagery filter for coverage, cones and nearest-image lookups. */
@@ -538,10 +590,17 @@ export function createStreetLevelLayer({
     openImage,
     /**
      * Open the nearest image any active provider (or only `providerIds`)
-     * has around a point, by default the view centre.
+     * has around a point; without one, around the view centre, or with
+     * `aim: 'screen-centre'` the ground under the middle of the screen.
      */
-    async openNearest(point, { providerIds = null, frame = true } = {}) {
-      const view = point || viewCentre(state.viewer);
+    async openNearest(
+      point,
+      { providerIds = null, frame = true, aim = 'view' } = {},
+    ) {
+      const view =
+        point ||
+        (aim === 'screen-centre' && screenCentreGround()) ||
+        viewCentre(state.viewer);
       if (!Number.isFinite(view?.lat) || !Number.isFinite(view?.lon))
         return false;
       abortNearest();

src/layers/streetLevel/index.test.mjs

@@ -502,15 +502,16 @@ async function withStreetView(t, { mapStack = 'photoreal', nearest } = {}) {
     },
   });
   mapillary.requiresKeyId = 'mapillary';
+  const loader = fakeMapsLoader(fake.library);
   const google = createGoogleProvider({
     getApiKey: () => 'browser-key',
-    loader: fakeMapsLoader(fake.library),
+    loader,
   });
   const { layer, viewer } = await enabledLayer(t, [mapillary, google]);
   const stack = fakeMapStack(mapStack);
   layer.attachMapStackController(stack);
   layer.attachViewerHost(fakeHost());
-  return { layer, viewer, stack, fake, mapillaryLookups };
+  return { layer, viewer, stack, fake, loader, mapillaryLookups };
 }
 
 test('Street View starts off, and the layer row names the key of the providers that are on', async (t) => {
@@ -523,27 +524,42 @@ test('Street View starts off, and the layer row names the key of the providers t
   assert.equal(layer.requiresKeyId, null, 'two keys: each chip names its own');
 });
 
-test('Street View opens only on the Google 3D map, and leaving that map closes it', async (t) => {
-  const { layer, stack } = await withStreetView(t, {
+test('Street View appears only on the Google 3D map: chip, legend, credit, source and images', async (t) => {
+  const { layer, viewer, stack } = await withStreetView(t, {
     mapStack: 'esri-imagery',
   });
   layer.setProviderEnabled('google', true);
   await settle();
-  const google = () =>
-    layer.getUIState().providers.find((p) => p.id === 'google');
-  assert.match(google().unavailable, /needs the Google 3D map/);
-  assert.equal(google().hint, '', 'no "click a street" off Google 3D');
+  const ui = () => layer.getUIState();
+  const listed = () => ui().providers.map((p) => p.id);
+  const credited = () =>
+    viewer.credits.some((credit) => /Street View imagery/.test(credit.html));
+  assert.deepEqual(listed(), ['mapillary'], 'no Street View chip');
+  assert.ok(!ui().legend.some((item) => item.key === 'google'));
+  assert.equal(credited(), false, 'no Google credit on another map');
+  assert.equal(layer.source, 'Mapillary');
+  assert.equal(layer.getStats().source, 'Mapillary');
   assert.equal(await layer.openImage('google', 'pano-a'), false);
-  assert.match(layer.getUIState().street.error, /needs the Google 3D map/);
+  assert.match(ui().street.error, /needs the Google 3D map/);
+  assert.equal(layer.getParams().google, true, 'the choice is kept');
 
   stack.switchTo('photoreal');
-  assert.equal(google().unavailable, null);
+  assert.deepEqual(listed(), ['mapillary', 'google']);
+  assert.equal(credited(), true);
+  assert.equal(layer.source, 'Mapillary · Google Street View');
   assert.equal(await layer.openImage('google', 'pano-a'), true);
-  assert.equal(layer.getUIState().street.providerId, 'google');
+  assert.equal(ui().street.providerId, 'google');
 
   stack.switchTo('bing');
   await settle();
-  assert.equal(layer.getUIState().street.open, false, 'closed with the map');
+  assert.equal(ui().street.open, false, 'closed with the map');
+  assert.equal(credited(), false);
+  assert.deepEqual(listed(), ['mapillary']);
+});
+
+test('the UI state says when a click (or the button) can open Street View here', async (t) => {
+  const { layer } = await withStreetView(t);
+  assert.equal(typeof layer.getUIState().groundClickReady, 'boolean');
 });
 
 test('a lookup for the click-to-open providers asks only them and reports "that point"', async (t) => {
@@ -575,3 +591,49 @@ test('an image opened from a ground click leaves the camera where it is', async
   assert.equal(layer.getUIState().street.imageId, 'pano-a');
   assert.equal(viewer.flights.started, 0, 'no framing flight');
 });
+
+test('off Google 3D not even Google\u2019s script is loaded for Street View', async (t) => {
+  const { layer, loader } = await withStreetView(t, {
+    mapStack: 'esri-imagery',
+  });
+  layer.setProviderEnabled('google', true);
+  layer.attachViewerHost({ ownerDocument: { createElement: () => ({}) } });
+  await new Promise((resolve) => setTimeout(resolve, 100));
+  assert.deepEqual(loader.imports, [], 'no prewarm, no lookup');
+});
+
+test('the button’s “centre of the view” is the ground under the middle of the screen', async (t) => {
+  const { createStreetLevelLayer: create } = await import('./index.js');
+  const scenePick = await import('../../data/scenePick.js');
+  const lookups = [];
+  const provider = fakeProvider({
+    nearestImage: async (point) => {
+      lookups.push(point);
+      return null;
+    },
+  });
+  const saved = globalThis.document;
+  const drawing = new Proxy({}, { get: () => () => ({ addColorStop() {} }) });
+  globalThis.document = Object.assign(new EventTarget(), {
+    createElement: () => ({ getContext: () => drawing }),
+  });
+  const viewer = fakeViewer();
+  const centre = Cesium.Cartesian3.fromDegrees(-121.4937, 38.5799, 0);
+  Object.assign(viewer.scene, {
+    pickPositionSupported: true,
+    pickPosition: (at) => (at.x === 500 && at.y === 300 ? centre : undefined),
+  });
+  viewer.scene.canvas.clientWidth = 1000;
+  viewer.scene.canvas.clientHeight = 600;
+  const layer = create({ providers: [provider], services: { scenePick } });
+  layer.init(viewer);
+  layer.enable(viewer);
+  t.after(() => {
+    layer.destroy();
+    globalThis.document = saved;
+  });
+  await layer.openNearest(undefined, { aim: 'screen-centre' });
+  assert.equal(lookups.length, 1);
+  assert.ok(Math.abs(lookups[0].lat - 38.5799) < 1e-9);
+  assert.ok(Math.abs(lookups[0].lon - -121.4937) < 1e-9);
+});

src/layers/streetLevel/providers/google/viewer.js

@@ -254,15 +254,6 @@ export function createGoogleViewer({ loader, getService, render } = {}) {
       }
     },
 
-    /** Load the library ahead of the first panorama; a panorama is billed, so none is built. */
-    async prewarm() {
-      try {
-        await ensureLibrary();
-      } catch {
-        /* the real open reports errors */
-      }
-    },
-
     onPose(listener) {
       listeners.add(listener);
       return () => listeners.delete(listener);

src/layers/streetLevel/providers/google/viewer.test.mjs

@@ -130,11 +130,8 @@ test('an open overtaken by a newer one only shows the newer panorama', async ()
   assert.ok(!poses.some((pose) => pose.imageId === 'pano-a'));
 });
 
-test('unmounting removes the element and every listener; prewarm builds no panorama', async () => {
-  const { fake, loader, viewer, host } = setup();
-  await viewer.prewarm(host);
-  assert.deepEqual(loader.imports, ['streetView']);
-  assert.equal(fake.built.length, 0, 'a panorama is billed: none on prewarm');
+test('unmounting removes the element and every listener', async () => {
+  const { fake, viewer, host } = setup();
   await viewer.mount(host);
   const [panorama] = fake.built;
   assert.ok(panorama.listenerCount() > 0);
@@ -144,6 +141,12 @@ test('unmounting removes the element and every listener; prewarm builds no panor
   await assert.rejects(viewer.open('pano-a'), /not mounted/);
 });
 
+test('there is no prewarm: Google\u2019s script loads on first use only, never on another map', () => {
+  const { viewer, loader } = setup();
+  assert.equal(viewer.prewarm, undefined);
+  assert.deepEqual(loader.imports, []);
+});
+
 test('a key Google refuses fails the open at once, not after the timeout', async () => {
   const { fake, loader, viewer, host } = setup();
   await viewer.mount(host);

src/layers/streetLevel/uiState.js

@@ -45,6 +45,7 @@ export function summarizeCoverage(providers) {
  */
 export function composeUIState({
   enabled,
+  groundClickReady = false,
   filter,
   providers,
   street,
@@ -63,6 +64,8 @@ export function composeUIState({
     legend.push({ key: 'selected', label: 'Selected', color: COLORS.selected });
   return {
     enabled,
+    /** The camera is at street zoom: a ground-click provider can open here. */
+    groundClickReady: groundClickReady === true,
     keyRequired,
     keyRejected,
     filter: { ...filter },

src/ui/streetLevelControls.js

@@ -66,6 +66,7 @@ export class StreetLevelControls {
       status: byId('sl-status'),
       controls: byId('sl-controls'),
       providerChips: byId('sl-provider-chips'),
+      nearestBtn: byId('sl-nearest-btn'),
       error: byId('sl-error'),
       errorText: byId('sl-error-text'),
       sinceRange: byId('sl-since'),
@@ -103,9 +104,18 @@ export class StreetLevelControls {
     this.listen(el.providerChips, 'click', (event) => {
       const button = event.target?.closest?.('.data-toggle-chip');
       if (!button || button.disabled) return;
-      // Without a key the chips stay focusable for their tooltip; a click
-      // says the same thing rather than switching on a layer that cannot draw.
-      if (this._view?.controlsDisabled) {
+      // A chip without a usable key stays focusable for its tooltip; a click
+      // that would light it, or switch the layer off through it, says the
+      // same thing instead. Other chips still switch (a refused Street View
+      // key cannot lock Mapillary out), and it darkens beside a lit one.
+      const providers = this._view?.providers || [];
+      const chip = providers.find(
+        (entry) => entry.id === button.dataset.chipId,
+      );
+      const othersLit = providers.some(
+        (entry) => entry.id !== chip?.id && entry.active,
+      );
+      if (chip?.state === 'error' && (!chip.active || !othersLit)) {
         if (button.title) this.actions.showToast?.(button.title);
         return;
       }
@@ -129,6 +139,17 @@ export class StreetLevelControls {
     this.listen(el.sinceRange, 'change', () =>
       this._setParams({ sinceDays: sinceDays() }),
     );
+    // The keyboard path to Street View: its nearest image at the view centre,
+    // without moving the camera.
+    this.listen(el.nearestBtn, 'click', () => {
+      const nearest = this._view?.nearest;
+      if (!nearest?.visible || nearest.disabled) return;
+      this.layer.openNearest?.(undefined, {
+        providerIds: nearest.providerIds,
+        frame: false,
+        aim: 'screen-centre',
+      });
+    });
     this.listen(el.followBtn, 'click', () => {
       this.layer.setFollow?.(!(this._state?.street?.follow === true));
     });
@@ -466,6 +487,7 @@ export class StreetLevelControls {
     this._renderFilters(view);
     this._renderViewer(view);
     this._renderMeta(view);
+    this._renderNearest(view);
     this._reactToTransitions(view, state);
   }
 
@@ -595,6 +617,17 @@ export class StreetLevelControls {
     setProp(this._elements.coverageMeta, 'textContent', view.meta);
   }
 
+  _renderNearest(view) {
+    const button = this._elements.nearestBtn;
+    if (!button) return;
+    const { nearest } = view;
+    setProp(button, 'hidden', !nearest.visible);
+    if (!nearest.visible) return;
+    setProp(button, 'textContent', nearest.label);
+    setProp(button, 'title', nearest.title);
+    setProp(button, 'disabled', nearest.disabled);
+  }
+
   /**
    * Open the panel on a switch-on or when an image opens. Never persisted:
    * the stored collapse state stays the user's own choice.

src/ui/streetLevelControls.test.mjs

@@ -305,6 +305,7 @@ function panelDom() {
   const settings = add(main, 'div', { classes: ['sl-settings'] });
   for (const id of ['sl-provider-chips', 'sl-error', 'sl-error-text'])
     add(settings, 'div', { id });
+  add(settings, 'button', { id: 'sl-nearest-btn' });
   // A missing key gates the filters only; the chips stay outside the gate.
   const controls = add(settings, 'fieldset', { id: 'sl-controls' });
   for (const pano of ['all', 'pano', 'flat'])
@@ -1136,3 +1137,72 @@ test('a <body> child added while the viewer is expanded goes inert with the rest
       assert.equal(observer.watching(), false);
     }),
   ));
+
+test('OPEN STREET VIEW opens the nearest panorama at the view centre without moving the camera', () =>
+  withDom(async (dom) => {
+    const state = uiState();
+    state.providers.push({
+      ...state.providers[0],
+      id: 'google',
+      name: 'Google Street View',
+      label: 'STREET VIEW',
+      groundClick: true,
+      count: 0,
+    });
+    state.groundClickReady = true;
+    const { layer } = stubPanel(dom, state);
+    const asked = [];
+    layer.openNearest = (point, options) => asked.push([point, options]);
+    const button = dom.root.querySelector('#sl-nearest-btn');
+    assert.equal(button.hidden, false);
+    assert.equal(button.textContent, 'OPEN STREET VIEW');
+    button.click();
+    assert.deepEqual(asked, [
+      [
+        undefined,
+        { providerIds: ['google'], frame: false, aim: 'screen-centre' },
+      ],
+    ]);
+    // Too high to mean a street: disabled, and a click does nothing.
+    layer.publish({ ...state, groundClickReady: false });
+    assert.equal(button.disabled, true);
+    button.click();
+    assert.equal(asked.length, 1);
+    // Off Google 3D the provider is not listed: no button.
+    layer.publish({ ...state, providers: [state.providers[0]] });
+    assert.equal(button.hidden, true);
+  }));
+
+test('a refused key on one provider leaves the other chip switchable, and the refused chip darkens beside it', () =>
+  withDom(async (dom) => {
+    const state = uiState({ on: false, keyRequired: true });
+    state.providers.push({
+      ...state.providers[0],
+      id: 'google',
+      name: 'Google Street View',
+      label: 'STREET VIEW',
+      on: true,
+      keyRequired: true,
+      keyRejected: true,
+      error: 'Google refused GOOGLE_MAPS_API_KEY for Street View',
+    });
+    state.providers[0].keyRequired = false;
+    const { calls, layer } = stubPanel(dom, state);
+    const chips = () => dom.root.querySelector('#sl-provider-chips').children;
+    chips()[0].click(); // Mapillary: configured, dark
+    await settle();
+    assert.deepEqual(calls.setParams, [
+      [{ mapillary: true }, { origin: 'user' }],
+    ]);
+    // With Mapillary lit, the refused Street View chip can be darkened.
+    state.providers[0].on = true;
+    state.keyRequired = false;
+    layer.publish({ ...state });
+    chips()[1].click();
+    await settle();
+    assert.deepEqual(calls.setParams.at(-1), [
+      { google: false },
+      { origin: 'user' },
+    ]);
+    assert.equal(calls.toasts.length, 0);
+  }));

src/ui/streetLevelPresentation.js

@@ -80,8 +80,6 @@ function presentProviders(state) {
     else if (keyRequired && provider.requiresKeyId)
       title = `${provider.name}: ${keySetupRequirement(provider.requiresKeyId)}`;
     else if (provider.error) title = `${provider.name}: ${provider.error}`;
-    // Usable only on another map stack (Street View off Google 3D).
-    else if (provider.unavailable) title = provider.unavailable;
     return {
       id: provider.id,
       label: provider.label,
@@ -91,13 +89,11 @@ function presentProviders(state) {
       disabled: false,
       state: keyRequired
         ? 'error'
-        : on && provider.unavailable
-          ? 'warn'
-          : on && provider.loading
-            ? 'loading'
-            : on
-              ? 'active'
-              : 'idle',
+        : on && provider.loading
+          ? 'loading'
+          : on
+            ? 'active'
+            : 'idle',
       busy: on && provider.loading === true,
     };
   });
@@ -134,6 +130,36 @@ function presentViewer(state) {
   };
 }
 
+/**
+ * A button for the providers with no coverage to click (Street View): opens
+ * their nearest image at the view centre, so they need no pointer.
+ */
+function presentNearest(state) {
+  const targets = (state.providers || []).filter(
+    (provider) =>
+      provider.on && provider.groundClick && provider.keyRequired !== true,
+  );
+  if (state.enabled !== true || !targets.length)
+    return {
+      visible: false,
+      label: '',
+      title: '',
+      disabled: true,
+      providerIds: [],
+    };
+  const names = targets.map((provider) => provider.name).join(' or ');
+  const ready = state.groundClickReady === true;
+  return {
+    visible: true,
+    label: `OPEN ${targets.map((provider) => provider.label).join(' / ')}`,
+    title: ready
+      ? `Open ${names} at the centre of the view`
+      : `Zoom in to a street to open ${names} here`,
+    disabled: !ready || state.street.loading === true,
+    providerIds: targets.map((provider) => provider.id),
+  };
+}
+
 function presentMeta(state) {
   if (!state.enabled) return 'Switch a provider on to draw its coverage.';
   if (state.sequence.selectedId)
@@ -173,6 +199,7 @@ export function presentStreetLevelPanel(state, { now = Date.now() } = {}) {
     legend: state.legend || [],
     viewer: presentViewer(state),
     meta: presentMeta(state),
+    nearest: presentNearest(state),
     wantsOpen: state.street.open === true,
   };
 }

src/ui/streetLevelPresentation.test.mjs

@@ -434,3 +434,52 @@ test('the meta line keeps the sequence count and adds the other providers’ hin
     `${(2514).toLocaleString()} sequences in view · click a line for its photos · click a street to open Street View`,
   );
 });
+
+test('OPEN STREET VIEW shows while Street View is on, and waits for street zoom', () => {
+  const streetView = provider({
+    id: 'google',
+    name: 'Google Street View',
+    label: 'STREET VIEW',
+    groundClick: true,
+    requiresKeyId: 'google-maps',
+  });
+  const view = (overrides) =>
+    presentStreetLevelPanel(
+      snapshot({
+        enabled: true,
+        providers: [provider(), streetView],
+        ...overrides,
+      }),
+    ).nearest;
+  const ready = view({ groundClickReady: true });
+  assert.deepEqual(ready, {
+    visible: true,
+    label: 'OPEN STREET VIEW',
+    title: 'Open Google Street View at the centre of the view',
+    disabled: false,
+    providerIds: ['google'],
+  });
+  const high = view({ groundClickReady: false });
+  assert.equal(high.disabled, true);
+  assert.equal(
+    high.title,
+    'Zoom in to a street to open Google Street View here',
+  );
+  // Hidden with Street View off, without its key, or with the layer off
+  // (off Google 3D the provider is not listed at all).
+  assert.equal(
+    view({ providers: [provider(), { ...streetView, on: false }] }).visible,
+    false,
+  );
+  assert.equal(
+    view({ providers: [provider(), { ...streetView, keyRequired: true }] })
+      .visible,
+    false,
+  );
+  assert.equal(view({ providers: [provider()] }).visible, false);
+  assert.equal(
+    presentStreetLevelPanel(snapshot({ providers: [provider(), streetView] }))
+      .nearest.visible,
+    false,
+  );
+});

src/ui/styles/street-level.css

@@ -183,10 +183,12 @@ button.sl-status:focus-visible {
   border-color: rgba(255, 179, 0, 0.55);
 }
 
-/* On, but not usable on this map stack (Street View off Google 3D). */
-.sl-chips .data-toggle-chip.chip-warn {
-  opacity: 0.7;
-  border-style: dashed;
+.sl-nearest-btn {
+  margin-left: auto;
+}
+
+.sl-nearest-btn[hidden] {
+  display: none;
 }
 
 /* ── Errors ──────────────────────────────────────────────────────────────── */

src/ui/templates/layer-panels.html

@@ -113,6 +113,7 @@
             <div class="sl-providers" role="group" aria-label="Imagery providers">
               <span class="cctv-summary-label">PROVIDERS</span>
               <div id="sl-provider-chips" class="sl-chips"></div>
+              <button id="sl-nearest-btn" class="scene-btn sl-nearest-btn" type="button" hidden>OPEN STREET VIEW</button>
             </div>
             <div id="sl-error" class="sl-error" role="alert" hidden><span aria-hidden="true">⚠</span> <span id="sl-error-text"></span></div>
             <!-- A missing key gates the filters only: the chips above stay