fix(street-level): Panoramax functional QA — nearest lookup, line cap order, hostile data

From an adversarial functional QA round against the live API:
- The nearest lookup missed pictures looking away from the click
  (place_position leaves them out at any tolerance): it now runs a
  bounding-box search beside it and ranks both by distance. A line
  clicked from high up searches its sequence within height / 100
  (50–400 m).
- The per-tile line cap kept the newest sequences, not the longest
  (lineCoverage re-sorted them): providers can now keep their decoded
  order (`keepOrder`).
- A long producer name froze the tab (quadratic email regex): linear
  check. A malformed link escape no longer fails the lookup; null or
  string coordinates no longer land at 0,0.
- A line with no camera type or day stays drawn under the filters.
- A sky click on a line changes nothing (as KartaView), instead of
  selecting a sequence with no cones.
- An unreadable tile reads as such; a failed neighbour z15 tile only
  thins the cones; unknown or refused ids say the picture is gone.
- Shared viewer: the sharp-panorama guard is per open (a late download
  of the previous photo no longer lets a second one start); an HD-only
  360° picture is shrunk or skipped like any original; panorama.js read
  the bitmap size after closing it, so 2:1 power-of-two panoramas
  clamped instead of wrapping.
- Tests for each, and for the gaps mutation testing found (preferred
  point, cone order, no reload within drawn tiles, newest-first gate,
  stale bitmap release, flat upgrade retry).

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

docs/CURRENT-STATE.md

@@ -3262,10 +3262,16 @@ density cells, binned to at most 96×96 points a tile (a z0 tile holds
 filters apply: lines carry their day and camera type, and a cell stays while
 it holds pictures of the kind asked for (cells are undated). A click on a
 line asks the core (`actions.openNearest`) for that sequence's picture
-nearest the click (`/api/search?place_position…&collections=<id>`, any
-direction: `place_fov_tolerance=180`), without framing, then any sequence's
-if it has none within 50 m; the filters go to the API (`filter=
-field_of_view=360`, `datetime=<since>/..`). Once the picture is on screen
+nearest the click, within the camera height / 100 (50–400 m: from high up
+a click lands well off a line), without framing, then any sequence's within
+50 m. Each lookup is two searches side by side, ranked by distance in the
+browser: `place_position` (nearest first, but even at
+`place_fov_tolerance=180` it leaves out pictures looking away from the
+point) and a bounding box (those too, but in no order); the filters go to
+both (`filter=field_of_view=360`, `datetime=<since>/..`). A line is dated
+by its sequence's first day, so a sequence still growing can hide under
+SINCE; a line with no camera type or day stays drawn. Lines keep the
+decoded longest-first order under the per-tile cap (`keepOrder`). Once the picture is on screen
 its sequence is highlighted and drawn as cones from the z15 tiles around it
 (their `pictures` layer, ~110 bytes a picture, against ~7.5 kB for a STAC
 item), plus a neighbour within 150 m of an edge; the cones re-centre when a

scripts/qa-street-level.mjs

@@ -2809,7 +2809,7 @@ async function main() {
         );
       if (fixtures)
         await step(
-          'every Mapillary and KartaView request was answered from a fixture',
+          'every Mapillary, KartaView and Panoramax request was answered from a fixture',
           () => {
             console.log(
               `  (answered: ${[...fixture.calls].sort().join(' | ')})`,

src/layers/streetLevel/lineCoverage.js

@@ -72,6 +72,7 @@ export function meshBoxInRange(box, centre) {
  * @property {number} viewRangeMinM       Street-zoom coverage reaches at least this far…
  * @property {number} viewRangePerHeight  …or camera height times this.
  * @property {number} viewNearM           Ground always covered around a tilted camera.
+ * @property {boolean} [keepOrder]        Cap a tile's lines in the order decoded (default: newest first).
  */
 
 /**
@@ -559,10 +560,13 @@ export function createLineCoverage({
         north: bounds.north + pad,
       };
       if (kind === 'sequence') {
-        // Newest first; the per-tile cap applies to what passes the filter.
-        entry.sequenceList = decoded.sequences.sort(
-          (a, b) => (b.capturedAt || 0) - (a.capturedAt || 0),
-        );
+        // Newest first, unless the provider ordered them itself; the
+        // per-tile cap applies to what passes the filter.
+        entry.sequenceList = tuning.keepOrder
+          ? decoded.sequences
+          : decoded.sequences.sort(
+              (a, b) => (b.capturedAt || 0) - (a.capturedAt || 0),
+            );
         entry.sequences = new Map();
         entry.total = decoded.sequences.length;
       } else {

src/layers/streetLevel/panorama.js

@@ -188,13 +188,15 @@ export function createPanoramaRenderer(canvas) {
         gl.UNSIGNED_BYTE,
         image,
       );
+      // Read before the close: a closed bitmap measures 0×0.
+      const { width, height } = image;
       // The pixels are on the GPU now; a bitmap's copy can go.
       image.close?.();
       // Linear only: a mipmapped lookup draws a seam where longitude wraps.
       gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
       gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
       const repeat =
-        isPowerOfTwo(image.width) && isPowerOfTwo(image.height)
+        isPowerOfTwo(width) && isPowerOfTwo(height)
           ? gl.REPEAT
           : gl.CLAMP_TO_EDGE;
       gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, repeat);

src/layers/streetLevel/panorama.test.mjs

@@ -167,3 +167,33 @@ test('an image uploads as RGBA and its bitmap is released; closing hands the tex
   );
   assert.equal(renderer.hasImage(), false);
 });
+
+test('a power-of-two bitmap wraps in longitude even though it is closed once uploaded', (t) => {
+  const { gl, renderer } = stubPanorama(t);
+  const wraps = [];
+  gl.texParameteri = (target, name, value) => wraps.push([name, value]);
+  gl.TEXTURE_WRAP_S = 'WRAP_S';
+  gl.REPEAT = 'REPEAT';
+  gl.CLAMP_TO_EDGE = 'CLAMP';
+  const bitmap = {
+    width: 2048,
+    height: 1024,
+    // A closed ImageBitmap measures 0×0.
+    close() {
+      this.width = 0;
+      this.height = 0;
+    },
+  };
+  renderer.setImage(bitmap);
+  assert.deepEqual(
+    wraps.find(([name]) => name === 'WRAP_S'),
+    ['WRAP_S', 'REPEAT'],
+  );
+  wraps.length = 0;
+  renderer.setImage({ width: 2000, height: 1000 });
+  assert.deepEqual(
+    wraps.find(([name]) => name === 'WRAP_S'),
+    ['WRAP_S', 'CLAMP'],
+    'other sizes clamp (WebGL 1 repeats powers of two only)',
+  );
+});

src/layers/streetLevel/photoViewer.js

@@ -90,8 +90,8 @@ export function panoSizeFor(canvasPixels, fovDeg) {
 /**
  * @typedef {object} PhotoSources   Where a provider's photo comes from.
  * @property {(photo: object) => boolean} hasPano   A 360° photo with an equirectangular image.
- * @property {(photo: object) => {url: string, width: number}|null} panoFirst
- *   The panorama shown first, and its texture width (0 when it is only a preview).
+ * @property {(photo: object) => {url: string, width: number, resize?: [number, number]|null}|null} panoFirst
+ *   The panorama shown first, its texture width (0 when it is only a preview), and a size to shrink it to.
  * @property {(photo: object, size: [number, number]) => {url: string, resize?: [number, number]|null, timeoutMs?: number}|null} panoSharp
  *   A sharper panorama for a canvas that needs `size`, or null.
  * @property {(photo: object) => Array<string>} flatFirst   Flat versions to try in turn.
@@ -158,8 +158,8 @@ export function createPhotoViewer({
   let restoreView = null;
   /** Width of the panorama texture on screen (0: the preview). */
   let panoWidth = 0;
-  /** Width of a sharper panorama on its way (resizes come in bursts). */
-  let panoComing = 0;
+  /** The sharper panorama on its way, for which open (resizes come in bursts). */
+  let panoComing = null;
   /** The sharper flat version on screen or on its way (one download each). */
   let flatSharpUrl = null;
   /** The photo an open is fetching: ‹ › step on from it, not the old one. */
@@ -520,10 +520,12 @@ export function createPhotoViewer({
     if (kind === 'flat' && target.isPano) return;
     if (kind === 'pano') {
       const size = panoSizeNow();
-      if (size[0] <= Math.max(panoWidth, panoComing)) return;
+      if (size[0] <= panoWidth) return;
+      if (panoComing?.seq === seq && size[0] <= panoComing.width) return;
       const sharp = sources.panoSharp(target, size);
       if (!sharp?.url) return;
-      panoComing = size[0];
+      const coming = { seq, width: size[0] };
+      panoComing = coming;
       try {
         const image = await loadAs(sharp.url, {
           crossOrigin: true,
@@ -544,7 +546,7 @@ export function createPhotoViewer({
       } catch {
         /* the first version stays */
       } finally {
-        if (panoComing === size[0]) panoComing = 0;
+        if (panoComing === coming) panoComing = null;
       }
       return;
     }
@@ -574,7 +576,10 @@ export function createPhotoViewer({
     // waiting on it twice.
     const first = sources.panoFirst(target);
     if (!first?.url) throw new Error(LOAD_FAILED);
-    const image = await loadAs(first.url, { crossOrigin: true });
+    const image = await loadAs(first.url, {
+      crossOrigin: true,
+      resize: first.resize ?? null,
+    });
     if (seq !== openSeq) {
       image.close?.();
       return false;
@@ -592,7 +597,7 @@ export function createPhotoViewer({
     show('pano');
     renderer.setImage(image);
     panoWidth = first.width || 0;
-    panoComing = 0;
+    panoComing = null;
     return true;
   }
 

src/layers/streetLevel/photoViewer.test.mjs

@@ -0,0 +1,134 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { createPhotoViewer } from './photoViewer.js';
+import { fakeHost, until } from '../../testSupport/kartaViewFakes.mjs';
+
+const PHOTOS = {
+  a: { id: 'a', sequenceId: 's', lon: 1, lat: 2, heading: 0, isPano: true },
+  b: { id: 'b', sequenceId: 's', lon: 1, lat: 2, heading: 0, isPano: true },
+  f: { id: 'f', sequenceId: 's', lon: 1, lat: 2, heading: 0, isPano: false },
+};
+
+/** Sources whose panoramas and sharper flat versions are named after the photo. */
+const SOURCES = {
+  hasPano: (photo) => photo.isPano,
+  panoFirst: (photo) => ({ url: `${photo.id}-first`, width: 2048 }),
+  panoSharp: (photo) => ({ url: `${photo.id}-sharp` }),
+  flatFirst: (photo) => [`${photo.id}-first`],
+  flatSharp: (photo, pixels) => (pixels > 1000 ? `${photo.id}-sharp` : null),
+  describe: () => ({ externalUrl: 'https://example.org' }),
+};
+
+/** A viewer whose loads wait until `release(url)` (or fail with `fail(url)`). */
+function setup() {
+  const pending = new Map();
+  const loads = [];
+  const images = [];
+  const viewer = createPhotoViewer({
+    providerId: 'test',
+    name: 'Test',
+    sources: SOURCES,
+    getPhoto: async (id) => PHOTOS[id],
+    step: async () => null,
+    onStep() {},
+    load: (url) =>
+      new Promise((resolve, reject) => {
+        loads.push(url);
+        pending.set(url, { resolve, reject });
+      }),
+    createRenderer: () => ({
+      setImage: (image) => images.push(image.src),
+      setView() {},
+      getView: () => ({ yaw: 0, pitch: 0, fov: 80 }),
+      resize() {},
+      clear() {},
+      destroy() {},
+    }),
+  });
+  const release = (url) => {
+    const closed = { value: false };
+    pending.get(url).resolve({ src: url, close: () => (closed.value = true) });
+    pending.delete(url);
+    return closed;
+  };
+  const fail = (url) => {
+    pending.get(url).reject(new Error('gone'));
+    pending.delete(url);
+  };
+  return { viewer, loads, images, release, fail, host: fakeHost() };
+}
+
+const tick = () => new Promise((resolve) => setTimeout(resolve, 0));
+const parts = (host) => {
+  const [picture, canvas] = host.children[0].children;
+  return { picture, canvas };
+};
+
+test('a panorama that arrives after another photo opened is released, not shown', async () => {
+  const env = setup();
+  await env.viewer.mount(env.host);
+  const first = env.viewer.open('a');
+  await tick();
+  const second = env.viewer.open('b');
+  await tick();
+  const stale = env.release('a-first');
+  await first;
+  assert.equal(stale.value, true, 'its bitmap is closed');
+  env.release('b-first');
+  await second;
+  assert.deepEqual(env.images, ['b-first']);
+});
+
+test('one sharp panorama download per open, even across a quick switch and a burst of resizes', async (t) => {
+  const env = setup();
+  t.after(() => delete globalThis.devicePixelRatio);
+  globalThis.devicePixelRatio = 1;
+  await env.viewer.mount(env.host);
+  const { canvas } = parts(env.host);
+  canvas.clientWidth = 1800;
+  const opening = env.viewer.open('a');
+  await tick();
+  env.release('a-first');
+  await opening;
+  await tick();
+  assert.ok(env.loads.includes('a-sharp'), 'expanded: the sharp one is asked');
+  // Photo b opens while a's sharp version is still on its way.
+  const next = env.viewer.open('b');
+  await tick();
+  env.release('b-first');
+  await next;
+  await tick();
+  assert.ok(env.loads.includes('b-sharp'));
+  // a's download finishes late; resizes must not ask for b's again.
+  env.release('a-sharp');
+  await tick();
+  env.viewer.resize();
+  env.viewer.resize();
+  await tick();
+  assert.equal(env.loads.filter((url) => url === 'b-sharp').length, 1);
+  env.release('b-sharp');
+  await tick();
+  assert.deepEqual(env.images, ['a-first', 'b-first', 'b-sharp']);
+});
+
+test('a sharper flat version that failed is tried again on the next resize', async (t) => {
+  const env = setup();
+  t.after(() => delete globalThis.devicePixelRatio);
+  globalThis.devicePixelRatio = 1;
+  await env.viewer.mount(env.host);
+  const { picture } = parts(env.host);
+  picture.clientWidth = 1200;
+  const opening = env.viewer.open('f');
+  await tick();
+  env.release('f-first');
+  await opening;
+  await tick();
+  env.fail('f-sharp');
+  await tick();
+  assert.equal(picture.src, 'f-first');
+  env.viewer.resize();
+  await tick();
+  assert.equal(env.loads.filter((url) => url === 'f-sharp').length, 2);
+  env.release('f-sharp');
+  assert.ok(await until(() => picture.src === 'f-sharp'));
+});

src/layers/streetLevel/providers/panoramax/decode.js

@@ -54,7 +54,13 @@ export function decodeCoverageTile(bytes, address) {
         id: String(props.id),
         parts,
         capturedAt: dayMs(props.date),
-        isPano: props.type === 'equirectangular',
+        // A sequence with no camera type is neither (the filters keep it).
+        isPano:
+          props.type === 'equirectangular'
+            ? true
+            : props.type === 'flat'
+              ? false
+              : null,
       };
       lengths.set(sequence, length);
       result.sequences.push(sequence);

src/layers/streetLevel/providers/panoramax/decode.test.mjs

@@ -47,6 +47,24 @@ test('sequence lines keep their parts apart, with their day and camera type', ()
   assert.equal(pano.parts.length, 2, 'the gap is not bridged');
   assert.ok(near(pano.parts[1][1][0], lon + 0.001));
   assert.equal(flat.isPano, false);
+  const untyped = decodeCoverageTile(
+    encodePanoramaxTile(tile, {
+      sequences: [
+        {
+          id: 'u',
+          type: '',
+          parts: [
+            [
+              [lon, lat],
+              [lon + 0.001, lat],
+            ],
+          ],
+        },
+      ],
+    }),
+    tile,
+  ).sequences[0];
+  assert.equal(untyped.isPano, null, 'no camera type: neither');
 });
 
 test('density cells bin to a bounded number of points that keep the counts and kinds', () => {

src/layers/streetLevel/providers/panoramax/index.js

@@ -18,7 +18,10 @@ import {
   COVERAGE_Z12_BELOW_M,
   COVERAGE_Z13_BELOW_M,
   COVERAGE_Z14_BELOW_M,
+  GONE_MESSAGE,
   LINE_CLICK_HINT,
+  LINE_CLICK_RADIUS_MAX_M,
+  LINE_CLICK_RADIUS_PER_HEIGHT,
   NEAREST_LIMIT,
   NEAREST_RADIUS_M,
   NO_COVERAGE_HINT,
@@ -31,13 +34,31 @@ import {
   PICTURE_TILE_EDGE_M,
   PICTURE_TILE_ZOOM,
   RATE_LIMITED_MESSAGE,
+  UNREADABLE_TILE_MESSAGE,
   normalizeItem,
 } from './policy.js';
 
 export { PANORAMAX_PROVIDER_ID } from './policy.js';
 
+/**
+ * A tile's bytes decoded by `decode`; a body that is not a vector tile
+ * (an HTML error page, a cut-off answer) reads as such, not as a parser's
+ * "Unimplemented type: 4".
+ */
+async function readable(decode) {
+  try {
+    return await decode();
+  } catch (error) {
+    if (error?.name === 'AbortError' || error?.status !== undefined)
+      throw error;
+    throw new Error(UNREADABLE_TILE_MESSAGE);
+  }
+}
+
 /** Pictures kept in memory by id (lookups and ‹ › fill it). */
 const PHOTO_CACHE_SIZE = 2000;
+/** Sequences whose cone centre is remembered. */
+const ANCHOR_CACHE_SIZE = 50;
 
 /**
  * Sequence lines at z11–14 below 30 km; above, the density grid at z5 and
@@ -63,17 +84,23 @@ export function panoramaxZoomFor(heightM) {
 }
 
 /**
- * The imagery filter for lines (dated, typed) and grid cells (undated, with
- * 360° and flat counts): a cell stays while it holds pictures of the kind
- * asked for.
+ * The imagery filter for lines and grid cells. A cell (undated, with 360°
+ * and flat counts) stays while it holds pictures of the kind asked for. A
+ * line is dated by its sequence's first day, so a sequence still growing
+ * may hide under "since" while its newer pictures can be opened; a line
+ * with no camera type or no day is kept (a click finds out).
  */
 export function passesCoverage(record, filter) {
+  if (!filter) return true;
   if ('hasPano' in record) {
-    if (filter?.pano === 'pano') return record.hasPano;
-    if (filter?.pano === 'flat') return record.hasFlat;
+    if (filter.pano === 'pano') return record.hasPano;
+    if (filter.pano === 'flat') return record.hasFlat;
     return true;
   }
-  return passesImageryFilter(record, filter);
+  return passesImageryFilter(record, {
+    pano: typeof record.isPano === 'boolean' ? filter.pano : 'all',
+    sinceMs: record.capturedAt ? filter.sinceMs : null,
+  });
 }
 
 /** Least-recently-used map: reading an entry renews it. */
@@ -193,7 +220,7 @@ export function createPanoramaxProvider({
       };
       const photos = createLru(PHOTO_CACHE_SIZE);
       /** Where each sequence's cones centre: the picture last opened in it, or a click. */
-      const anchors = new Map();
+      const anchors = createLru(ANCHOR_CACHE_SIZE);
       /** The z15 tiles the cones were drawn from. */
       let drawn = null;
       /** A line click: its sequence's pictures win the next nearest lookup there. */
@@ -215,10 +242,14 @@ export function createPanoramaxProvider({
         if (!lookup) {
           lookup = source
             .getItem(id)
+            .catch((error) => {
+              // Ids are UUIDs: the API answers 400 to anything else.
+              if (error?.status === 400) return null;
+              throw error;
+            })
             .then((item) => {
               const photo = item && remember(item);
-              if (!photo)
-                throw new Error('Panoramax has no position for this picture');
+              if (!photo) throw new Error(GONE_MESSAGE);
               return photo;
             })
             .finally(() => inflight.delete(id));
@@ -227,6 +258,19 @@ export function createPanoramaxProvider({
         return lookup;
       }
 
+      /**
+       * How far from a line click its sequence's pictures are looked for:
+       * from high up the click may land tens of metres off the line.
+       */
+      function lineClickRadius() {
+        const height = state.viewer?.camera?.positionCartographic?.height;
+        if (!Number.isFinite(height)) return NEAREST_RADIUS_M;
+        return Math.min(
+          LINE_CLICK_RADIUS_MAX_M,
+          Math.max(NEAREST_RADIUS_M, height * LINE_CLICK_RADIUS_PER_HEIGHT),
+        );
+      }
+
       /** The picture `delta` along its sequence, from its own links (null at an end). */
       async function step(photo, delta) {
         if (!photo?.sequenceId) return null;
@@ -236,7 +280,9 @@ export function createPanoramaxProvider({
       const coverage = createLineCoverage({
         state,
         fetchTile: async (tile, { signal }) =>
-          decodeCoverageTile(await source.getTile(tile, { signal }), tile),
+          readable(async () =>
+            decodeCoverageTile(await source.getTile(tile, { signal }), tile),
+          ),
         zoomFor: panoramaxZoomFor,
         colors: COLORS,
         pickPrefix: PICK_PREFIX.sequence,
@@ -252,18 +298,26 @@ export function createPanoramaxProvider({
           const anchor = anchors.get(sequenceId);
           if (!anchor) return [];
           const tiles = pictureTilesAround(anchor);
-          const lists = await Promise.all(
-            tiles.map(async (tile) =>
-              decodePictures(
-                await source.getTile(tile, { signal }),
-                tile,
-                sequenceId,
+          // The home tile must load; a neighbour that fails only thins the cones.
+          const lists = await Promise.allSettled(
+            tiles.map((tile) =>
+              readable(async () =>
+                decodePictures(
+                  await source.getTile(tile, { signal }),
+                  tile,
+                  sequenceId,
+                ),
               ),
             ),
           );
           signal?.throwIfAborted();
+          if (lists[0].status === 'rejected') throw lists[0].reason;
           drawn = { sequenceId, tiles: new Set(tiles.map(tileKey)) };
-          const byId = new Map(lists.flat().map((image) => [image.id, image]));
+          const byId = new Map(
+            lists
+              .flatMap((list) => list.value ?? [])
+              .map((image) => [image.id, image]),
+          );
           return thinImages(
             [...byId.values()].sort((a, b) => a.capturedAt - b.capturedAt),
           );
@@ -302,14 +356,14 @@ export function createPanoramaxProvider({
         ...viewerOptions,
       });
 
-      /** Nearest of `items` within the search radius of a point, or null. */
-      function nearestOf(items, point) {
+      /** Nearest of `items` within `radius` metres of a point, or null. */
+      function nearestOf(items, point, radius = NEAREST_RADIUS_M) {
         let best = null;
         for (const item of items) {
           const photo = remember(item);
           if (!photo) continue;
           const metres = metresBetween(point, photo);
-          if (metres > NEAREST_RADIUS_M) continue;
+          if (metres > radius) continue;
           if (!best || metres < best.metres) best = { photo, metres };
         }
         return best?.photo ?? null;
@@ -398,13 +452,15 @@ export function createPanoramaxProvider({
           const sequenceId = sequenceIdFromPick(pickId, PICK_PREFIX.sequence);
           if (!sequenceId) return false;
           const point = groundPoint?.();
-          if (!point) {
-            // No ground under the click: show the line selected, nothing more.
-            cones.select(sequenceId);
-            return true;
-          }
+          // No ground under the click (the sky beyond a line): nothing to open.
+          if (!point) return true;
           anchors.set(sequenceId, { ...point, sequenceId });
-          preferred = { sequenceId, lon: point.lon, lat: point.lat };
+          preferred = {
+            sequenceId,
+            lon: point.lon,
+            lat: point.lat,
+            radius: lineClickRadius(),
+          };
           context.actions.openNearest(point);
           return true;
         },
@@ -429,17 +485,16 @@ export function createPanoramaxProvider({
         async nearestImage({ lat, lon }, { signal } = {}) {
           const point = { lat, lon };
           const filter = context.getFilter();
+          // Only the lookup the click itself asked for (the same point).
           const wanted =
-            preferred && metresBetween(preferred, point) < 1
-              ? preferred.sequenceId
-              : null;
+            preferred && metresBetween(preferred, point) < 1 ? preferred : null;
           preferred = null;
-          const ask = (collections) =>
+          const ask = (collections, radius = NEAREST_RADIUS_M) =>
             source.nearestItems(
               {
                 lat,
                 lon,
-                radius: NEAREST_RADIUS_M,
+                radius,
                 limit: NEAREST_LIMIT,
                 collections,
                 pano: filter.pano,
@@ -448,7 +503,11 @@ export function createPanoramaxProvider({
               { signal },
             );
           if (wanted) {
-            const hit = nearestOf(await ask(wanted), point);
+            const hit = nearestOf(
+              await ask(wanted.sequenceId, wanted.radius),
+              point,
+              wanted.radius,
+            );
             if (hit) return hit.id;
           }
           return nearestOf(await ask(null), point)?.id ?? null;

src/layers/streetLevel/providers/panoramax/policy.js

@@ -41,10 +41,12 @@ export const COVERAGE_LINES_BELOW_M = 30_000;
 export const COVERAGE_TUNING = Object.freeze({
   maxTiles: 9,
   overviewMaxTiles: 6,
-  // Each tile draws at most 1,600 lines, its longest first: a dense z11
+  // Each tile draws at most 1,600 lines, its longest first (as decoded,
+  // `keepOrder`): a dense z11
   // tile over Paris holds 3,800, and a lower cap left the city centre
   // looking emptier than its suburbs. (KartaView draws as many.)
   maxSequences: 14_400,
+  keepOrder: true,
   lineWidthPx: 2.5,
   overviewPointPx: 4,
   moveDebounceMs: 320,
@@ -61,6 +63,9 @@ export const OVERVIEW_BINS_PER_AXIS = 96;
 export const RATE_LIMITED_MESSAGE =
   'Panoramax is busy — coverage resumes on its own';
 export const NO_COVERAGE_HINT = 'no Panoramax pictures in view';
+export const UNREADABLE_TILE_MESSAGE =
+  'Panoramax sent a map tile that could not be read';
+export const GONE_MESSAGE = 'This Panoramax picture is no longer available';
 /** From high up the dots are where pictures are, not sequences to click. */
 export const OVERVIEW_HINT = 'zoom in to click a Panoramax sequence';
 
@@ -79,8 +84,20 @@ export const TILE_CONCURRENCY = 6;
 
 /** Pictures asked for around a point; the API returns them nearest first. */
 export const NEAREST_LIMIT = 10;
-/** Any picture within the radius, whichever way it looks (2–180°). */
+/**
+ * The widest the API allows: the point may be beside a picture, but a
+ * picture looking away from it is still left out (the bounding-box search
+ * beside it has those).
+ */
 export const NEAREST_FOV_TOLERANCE_DEG = 180;
+/** Pictures in the bounding box around a click, at most. */
+export const NEAREST_BOX_LIMIT = 100;
+/**
+ * A line clicked from high up may be tens of metres off the click: its
+ * sequence is searched within the camera height / 100 (50–400 m).
+ */
+export const LINE_CLICK_RADIUS_PER_HEIGHT = 0.01;
+export const LINE_CLICK_RADIUS_MAX_M = 400;
 
 /** A full-resolution panorama is only fetched up to this width (memory). */
 export const PANO_HD_MAX_WIDTH = 8_192;
@@ -147,7 +164,19 @@ function linkedId(item, rel) {
   const href = item?.links?.find?.((link) => link?.rel === rel)?.href;
   if (typeof href !== 'string') return null;
   const id = href.split(/[?#]/)[0].split('/').filter(Boolean).pop();
-  return id ? decodeURIComponent(id) : null;
+  if (!id) return null;
+  try {
+    return decodeURIComponent(id);
+  } catch {
+    // A malformed escape is no link, not a failed lookup.
+    return null;
+  }
+}
+
+/** An email address anywhere in a name (linear: names come from any instance). */
+function looksLikeEmail(name) {
+  const at = name.indexOf('@');
+  return at > 0 && name.indexOf('.', at + 2) !== -1;
 }
 
 /**
@@ -165,7 +194,7 @@ function creatorOf(item) {
       : []),
   ];
   const name = names.find((value) => typeof value === 'string' && value.trim());
-  if (!name || /\S+@\S+\.\S+/.test(name)) return null;
+  if (!name || looksLikeEmail(name)) return null;
   return name.trim().slice(0, 80);
 }
 
@@ -184,8 +213,11 @@ export function isEquirectangular(item) {
  */
 export function normalizeItem(item) {
   if (!item || item.id == null) return null;
+  // Only numbers: Number(null) and Number('') would put a picture at 0,0.
   const [lon, lat] = Array.isArray(item.geometry?.coordinates)
-    ? item.geometry.coordinates.map(Number)
+    ? item.geometry.coordinates.map((value) =>
+        typeof value === 'number' ? value : NaN,
+      )
     : [NaN, NaN];
   if (!Number.isFinite(lat) || !Number.isFinite(lon)) return null;
   if (Math.abs(lat) > 90 || Math.abs(lon) > 180) return null;

src/layers/streetLevel/providers/panoramax/policy.test.mjs

@@ -193,3 +193,35 @@ test('the caption link opens the picture in the Panoramax viewer', () => {
   assert.equal(panoramaxPictureUrl(null), 'https://api.panoramax.xyz/');
   assert.ok(panoramaxPictureUrl('a&b=c').includes('pic=a%26b%3Dc'));
 });
+
+test('hostile item data: a malformed link escape, null coordinates, a huge producer name', () => {
+  const item = stacItem({ id: 'a', lon: 1, lat: 2, nextId: 'n' });
+  item.links.push({
+    rel: 'prev',
+    href: 'https://api.panoramax.xyz/api/collections/s/items/%E0%A4%A',
+  });
+  const photo = normalizeItem(item);
+  assert.equal(photo.prevId, null, 'no link, no throw');
+  assert.equal(photo.nextId, 'n');
+  for (const coordinates of [[null, null], ['', ''], ['2.35', '48.85'], [2.35]])
+    assert.equal(
+      normalizeItem({ id: 'x', geometry: { coordinates } }),
+      null,
+      JSON.stringify(coordinates),
+    );
+  // A million characters without spaces is checked in linear time.
+  const started = Date.now();
+  const huge = normalizeItem(
+    stacItem({ id: 'a', lon: 1, lat: 2, producer: 'a'.repeat(1_000_000) }),
+  );
+  assert.ok(Date.now() - started < 500, `${Date.now() - started} ms`);
+  assert.equal(huge.creator.length, 80);
+  const named = (producer) =>
+    normalizeItem(stacItem({ id: 'a', lon: 1, lat: 2, producer })).creator;
+  assert.equal(named(`${'x'.repeat(200_000)}@example.org`), null);
+  assert.equal(
+    named('Carto@Cité'),
+    'Carto@Cité',
+    'an @ without a domain is a name',
+  );
+});

src/layers/streetLevel/providers/panoramax/provider.test.mjs

@@ -160,6 +160,20 @@ test('lines at z11–14 below 30 km; density points from z5 down to z0 above', (
   assert.equal(panoramaxZoomFor(NaN), null);
 });
 
+test('a line with no camera type or no day passes the filters: a click finds out', () => {
+  const filter = { pano: 'pano', sinceMs: Date.UTC(2024, 0, 1) };
+  assert.equal(
+    passesCoverage({ isPano: null, capturedAt: Date.UTC(2025, 0, 1) }, filter),
+    true,
+  );
+  assert.equal(passesCoverage({ isPano: true, capturedAt: 0 }, filter), true);
+  assert.equal(passesCoverage({ isPano: false, capturedAt: 0 }, filter), false);
+  assert.equal(
+    passesCoverage({ isPano: null, capturedAt: Date.UTC(2020, 0, 1) }, filter),
+    false,
+  );
+});
+
 test('the imagery filter: lines by type and day, density cells by what they hold', () => {
   const old = Date.UTC(2020, 0, 1);
   const since = { pano: 'all', sinceMs: Date.UTC(2024, 0, 1) };
@@ -314,9 +328,25 @@ test('one lookup for a picture asked twice at once', async () => {
   assert.deepEqual(source.calls.items, ['s-0']);
 });
 
-test('a picture Panoramax does not know fails the open with a reason', async () => {
+test('a picture Panoramax does not know, or an id it refuses, fails the open with a reason', async () => {
   const env = await mounted({ items: [] });
-  await assert.rejects(env.instance.viewer.open('ghost'), /no position/);
+  await assert.rejects(
+    env.instance.viewer.open('ghost'),
+    /no longer available/,
+  );
+  env.source.getItem = async () => {
+    throw Object.assign(new Error('Panoramax answered HTTP 400'), {
+      status: 400,
+    });
+  };
+  await assert.rejects(
+    env.instance.viewer.open('not-a-uuid'),
+    /no longer available/,
+  );
+  env.source.getItem = async () => {
+    throw Object.assign(new Error('Panoramax is busy'), { status: 503 });
+  };
+  await assert.rejects(env.instance.viewer.open('busy'), /busy/);
 });
 
 /** Cones on a stand-in Cesium viewer; `count()` reads how many are drawn. */
@@ -340,7 +370,13 @@ async function withCones(t, env) {
     },
     camera: { positionWC: new Cesium.Cartesian3(0, 0, 1e8) },
   });
-  return { count: () => collection?.length ?? 0 };
+  return {
+    count: () => collection?.length ?? 0,
+    ids: () =>
+      Array.from({ length: collection?.length ?? 0 }, (_, i) =>
+        String(collection.get(i).id).replace(PICK_PREFIX.image, ''),
+      ),
+  };
 }
 
 /** z15 tiles holding every item of `items` as a picture. */
@@ -379,18 +415,148 @@ test('once a picture is on screen its sequence’s cones load from the z15 tile
   assert.ok(env.source.calls.tiles.every((key) => key.startsWith('15/')));
 });
 
-test('a sequence selected with no picture or click to centre on draws no cones', async (t) => {
+test('a click on a line with no ground under it changes nothing: the open sequence keeps its cones', async (t) => {
+  const items = [...sequence('x', 6), ...sequence('y', 3, { offset: 3 })];
+  const env = await mounted({ items, tiles: pictureTiles(items) });
+  const cones = await withCones(t, env);
+  await env.instance.viewer.open('x-1');
+  await env.instance.selectSequence('x');
+  assert.ok(await until(() => cones.count() === 6));
+  const asked = env.source.calls.tiles.length;
+  assert.equal(
+    env.instance.handlePick(`${PICK_PREFIX.sequence}y`, {
+      groundPoint: () => null,
+    }),
+    true,
+    'the click is the provider’s, even with nothing to open',
+  );
+  await new Promise((resolve) => setTimeout(resolve, 0));
+  assert.equal(env.instance.sequenceStats().selectedId, 'x');
+  assert.equal(cones.count(), 6);
+  assert.equal(env.source.calls.tiles.length, asked);
+  assert.deepEqual(env.actions.nearest, []);
+});
+
+test('a sequence selected with nothing to centre on draws no cones, and a picture opening in it then does not throw', async (t) => {
   const items = sequence('s', 3);
   const env = await mounted({ items, tiles: pictureTiles(items) });
   await withCones(t, env);
-  env.instance.handlePick(`${PICK_PREFIX.sequence}s`, {
-    groundPoint: () => null,
-  });
-  assert.ok(await until(() => !env.instance.sequenceStats().loading));
-  assert.equal(env.instance.sequenceStats().selectedId, 's', 'highlighted');
+  await env.instance.selectSequence('s');
   assert.equal(env.instance.sequenceStats().images, 0);
   assert.deepEqual(env.source.calls.tiles, []);
-  assert.deepEqual(env.actions.nearest, []);
+  // Its first picture opens: the cones load around it.
+  await env.instance.viewer.open('s-0');
+  await env.instance.selectSequence('s');
+  assert.ok(await until(() => env.instance.sequenceStats().images === 3));
+});
+
+test('a line clicked from high up looks for its sequence further off; the radius grows with height, up to 400 m', async () => {
+  const items = [
+    ...sequence('near', 1),
+    ...sequence('line', 1, { offset: 220 }),
+  ];
+  const { instance, source } = setup({ items });
+  const height = (h) =>
+    instance.init({
+      camera: { positionCartographic: { height: h } },
+      scene: {
+        primitives: { add() {}, remove() {} },
+        preRender: { addEventListener: () => () => {} },
+      },
+    });
+  const click = () =>
+    instance.handlePick(`${PICK_PREFIX.sequence}line`, {
+      groundPoint: () => east(0),
+    });
+  height(25_000);
+  click();
+  assert.equal(
+    await instance.nearestImage(east(0)),
+    'line-0',
+    '220 m off, from 25 km',
+  );
+  assert.equal(source.calls.nearest.at(-1).radius, 250);
+  height(1_000);
+  click();
+  assert.equal(
+    await instance.nearestImage(east(0)),
+    'near-0',
+    'from 1 km only 50 m: any sequence’s nearer picture',
+  );
+  height(900_000);
+  click();
+  await instance.nearestImage(east(0));
+  assert.equal(
+    source.calls.nearest.filter((q) => q.collections === 'line').at(-1).radius,
+    400,
+    'capped',
+  );
+});
+
+test('a lookup at another point does not take a line click’s sequence', async () => {
+  const items = [
+    ...sequence('other', 1),
+    ...sequence('clicked', 1, { offset: 8 }),
+  ];
+  const { instance, source } = setup({ items });
+  instance.handlePick(`${PICK_PREFIX.sequence}clicked`, {
+    groundPoint: () => east(1),
+  });
+  // OPEN at the view centre, a few metres away, overtakes the click.
+  assert.equal(await instance.nearestImage(east(3)), 'other-0');
+  assert.deepEqual(
+    source.calls.nearest.map((q) => q.collections),
+    [null],
+  );
+});
+
+test('the cones come in capture order, and a broken neighbour tile only thins them', async (t) => {
+  const items = sequence('s', 5).map((item, i) => ({
+    ...item,
+    properties: {
+      ...item.properties,
+      // Captured in reverse of their position along the street.
+      datetime: `2025-06-01T10:00:0${9 - i}+00:00`,
+    },
+  }));
+  const tiles = pictureTiles(items);
+  const env = await mounted({ items, tiles });
+  const cones = await withCones(t, env);
+  await env.instance.viewer.open('s-0');
+  await env.instance.selectSequence('s');
+  assert.ok(await until(() => cones.count() === 5));
+  assert.deepEqual(cones.ids(), ['s-4', 's-3', 's-2', 's-1', 's-0']);
+  // A neighbour answers with garbage: the home tile's cones still draw.
+  const home = new Set();
+  env.source.getTile = async (tile) => {
+    const key = `${tile.z}/${tile.x}/${tile.y}`;
+    if (!home.size) home.add(key);
+    if (!home.has(key)) return new TextEncoder().encode('<html>oops</html>');
+    return tiles(tile);
+  };
+  await env.instance.viewer.open('s-0');
+  await env.instance.selectSequence('s');
+  assert.ok(await until(() => !env.instance.sequenceStats().loading));
+  // The home tile itself unreadable: a readable error, not a parser's.
+  env.source.getTile = async () =>
+    new TextEncoder().encode('<html>oops</html>');
+  await env.instance.selectSequence('s');
+  assert.ok(await until(() => env.actions.errors.some(Boolean)));
+  assert.match(env.actions.errors.filter(Boolean).at(-1), /could not be read/);
+});
+
+test('› within the tiles the cones came from reloads nothing', async (t) => {
+  const items = sequence('s', 4);
+  const env = await mounted({ items, tiles: pictureTiles(items) });
+  await withCones(t, env);
+  await env.instance.viewer.open('s-0');
+  await env.instance.selectSequence('s');
+  assert.ok(await until(() => env.instance.sequenceStats().images === 4));
+  const asked = env.source.calls.tiles.length;
+  env.next.fire('click');
+  assert.ok(await until(() => env.poses.at(-1) === 's-1'));
+  await new Promise((resolve) => setTimeout(resolve, 10));
+  assert.equal(env.source.calls.tiles.length, asked);
 });
 
 test('the cones re-centre when › walks into another z15 tile', async (t) => {

src/layers/streetLevel/providers/panoramax/source.js

@@ -3,6 +3,7 @@ import {
   API_CONCURRENCY,
   API_TIMEOUT_MS,
   MAX_RESPONSE_BYTES,
+  NEAREST_BOX_LIMIT,
   NEAREST_FOV_TOLERANCE_DEG,
   NEAREST_LIMIT,
   NEAREST_RADIUS_M,
@@ -151,9 +152,13 @@ export function createPanoramaxSource({
     },
 
     /**
-     * Pictures within `radius` metres of a point, nearest first, whichever
-     * way they look; `collections` keeps one sequence's, `pano` and
-     * `sinceMs` filter as the imagery filter does.
+     * Pictures within `radius` metres of a point, unranked: the caller ranks
+     * them by distance. Two searches side by side, since neither finds them
+     * all: `place_position` (nearest first) leaves out pictures looking
+     * away from the point, whatever the tolerance; a bounding box has them
+     * but in no order, so in a dense spot its page may miss the nearest.
+     * `collections` keeps one sequence's, `pano` and `sinceMs` filter as
+     * the imagery filter does.
      */
     async nearestItems(
       {
@@ -167,18 +172,40 @@ export function createPanoramaxSource({
       },
       { signal } = {},
     ) {
-      const params = {
-        place_position: `${Number(lon).toFixed(7)},${Number(lat).toFixed(7)}`,
-        place_distance: `0-${Math.min(1000, Math.max(1, Math.round(radius)))}`,
-        place_fov_tolerance: String(NEAREST_FOV_TOLERANCE_DEG),
-        limit: String(Math.min(100, Math.max(1, limit))),
-      };
-      if (collections) params.collections = String(collections);
-      if (pano === 'pano') params.filter = 'field_of_view=360';
-      else if (pano === 'flat') params.filter = 'field_of_view<360';
+      const metres = Math.min(1000, Math.max(1, Math.round(radius)));
+      const shared = {};
+      if (collections) shared.collections = String(collections);
+      if (pano === 'pano') shared.filter = 'field_of_view=360';
+      else if (pano === 'flat') shared.filter = 'field_of_view<360';
       if (Number.isFinite(sinceMs) && sinceMs > 0)
-        params.datetime = `${new Date(sinceMs).toISOString()}/..`;
-      return search(params, { signal });
+        shared.datetime = `${new Date(sinceMs).toISOString()}/..`;
+      const dLat = metres / 111_320;
+      const dLon =
+        metres / (111_320 * Math.max(0.01, Math.cos((lat * Math.PI) / 180)));
+      const box = [lon - dLon, lat - dLat, lon + dLon, lat + dLat].map((v) =>
+        v.toFixed(7),
+      );
+      const [facing, around] = await Promise.all([
+        search(
+          {
+            place_position: `${Number(lon).toFixed(7)},${Number(lat).toFixed(7)}`,
+            place_distance: `0-${metres}`,
+            place_fov_tolerance: String(NEAREST_FOV_TOLERANCE_DEG),
+            limit: String(Math.min(100, Math.max(1, limit))),
+            ...shared,
+          },
+          { signal },
+        ),
+        search(
+          { bbox: box.join(','), limit: String(NEAREST_BOX_LIMIT), ...shared },
+          { signal },
+        ),
+      ]);
+      const byId = new Map();
+      for (const item of [...facing, ...around])
+        if (item?.id != null && !byId.has(String(item.id)))
+          byId.set(String(item.id), item);
+      return [...byId.values()];
     },
   };
 }

src/layers/streetLevel/providers/panoramax/source.test.mjs

@@ -101,7 +101,7 @@ test('a picture by id is a STAC search; another id in the answer is not taken fo
   assert.equal(asked.searchParams.get('limit'), '1');
 });
 
-test('nearest pictures: any direction within the radius, filtered as the imagery filter asks', async () => {
+test('nearest pictures: a place search and a box search side by side, both filtered as the imagery filter asks', async () => {
   const { urls, fetchImpl } = fakeFetch(() => json({ features: [] }));
   const source = createPanoramaxSource({ fetchImpl });
   await source.nearestItems({ lat: 48.85, lon: 2.35 });
@@ -115,7 +115,13 @@ test('nearest pictures: any direction within the radius, filtered as the imagery
     limit: 500,
   });
   await source.nearestItems({ lat: 48.85, lon: 2.35, pano: 'flat' });
-  const [plain, filtered, flat] = urls.map((u) => new URL(u).searchParams);
+  const asked = urls.map((u) => new URL(u).searchParams);
+  assert.equal(asked.length, 6, 'two searches a lookup');
+  const place = asked.filter((q) => q.has('place_position'));
+  const box = asked.filter((q) => q.has('bbox'));
+  assert.equal(place.length, 3);
+  assert.equal(box.length, 3);
+  const [plain, filtered, flat] = place;
   assert.equal(plain.get('place_position'), '2.3500000,48.8500000');
   assert.equal(plain.get('place_distance'), '0-50');
   assert.equal(plain.get('place_fov_tolerance'), '180');
@@ -128,6 +134,53 @@ test('nearest pictures: any direction within the radius, filtered as the imagery
   assert.equal(filtered.get('place_distance'), '0-1000', 'capped');
   assert.equal(filtered.get('limit'), '100', 'capped');
   assert.equal(flat.get('filter'), 'field_of_view<360');
+  // The box spans the radius each way, and carries the same filters.
+  const [w, s, e, n] = box[0].get('bbox').split(',').map(Number);
+  assert.ok(Math.abs((n - s) * 111_320 - 100) < 1, `${n - s}°`);
+  assert.ok(
+    Math.abs((e - w) * 111_320 * Math.cos((48.85 * Math.PI) / 180) - 100) < 1,
+  );
+  assert.equal(box[1].get('collections'), 'seq');
+  assert.equal(box[1].get('filter'), 'field_of_view=360');
+  assert.equal(box[1].get('datetime'), '2025-01-01T00:00:00.000Z/..');
+  assert.equal(box[2].get('filter'), 'field_of_view<360');
+});
+
+test('a picture both searches find is listed once', async () => {
+  const source = createPanoramaxSource({
+    fetchImpl: fakeFetch((url) =>
+      url.includes('bbox')
+        ? json({ features: [{ id: 'b' }, { id: 'a' }, { id: null }] })
+        : json({ features: [{ id: 'a' }] }),
+    ).fetchImpl,
+  });
+  const items = await source.nearestItems({ lat: 1, lon: 2 });
+  assert.deepEqual(
+    items.map((i) => i.id),
+    ['a', 'b'],
+  );
+});
+
+test('the newest search goes first when the API gate is full', async () => {
+  const waiting = [];
+  const order = [];
+  const source = createPanoramaxSource({
+    fetchImpl: async (url) => {
+      order.push(new URL(url).searchParams.get('ids'));
+      await new Promise((resolve) => waiting.push(resolve));
+      return new Response(JSON.stringify({ features: [] }));
+    },
+  });
+  const all = ['1', '2', '3', '4', '5', '6'].map((id) => source.getItem(id));
+  await new Promise((resolve) => setTimeout(resolve, 0));
+  assert.deepEqual(order, ['1', '2', '3', '4'], 'four at once');
+  waiting.shift()();
+  await new Promise((resolve) => setTimeout(resolve, 0));
+  assert.equal(order.at(-1), '6', 'the latest waiting one next');
+  while (waiting.length) waiting.shift()();
+  await new Promise((resolve) => setTimeout(resolve, 0));
+  while (waiting.length) waiting.shift()();
+  await Promise.all(all);
 });
 
 test('an unreadable search answer, or one with no features, is handled', async () => {

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

@@ -1,4 +1,8 @@
-import { createPhotoViewer, loadImage } from '../../photoViewer.js';
+import {
+  PANO_FULL_SIZE,
+  createPhotoViewer,
+  loadImage,
+} from '../../photoViewer.js';
 import {
   HD_TIMEOUT_MS,
   PANORAMAX_NAME,
@@ -8,6 +12,13 @@ import {
   panoramaxPictureUrl,
 } from './policy.js';
 
+/** An HD original small enough to decode (its width is known and under the cap). */
+function hdDecodable(photo) {
+  return Boolean(
+    photo.urls.hd && photo.width && photo.width <= PANO_HD_MAX_WIDTH,
+  );
+}
+
 /**
  * Where Panoramax pictures come from: the instance holding each one serves
  * a 2,048 px SD derivative (equirectangular for a 360° picture) and the HD
@@ -16,11 +27,15 @@ import {
  * @type {import('../../photoViewer.js').PhotoSources}
  */
 export const PANORAMAX_SOURCES = Object.freeze({
-  hasPano: (photo) => Boolean(photo.isPano && (photo.urls.sd || photo.urls.hd)),
-  panoFirst: (photo) =>
-    photo.urls.sd
-      ? { url: photo.urls.sd, width: SD_WIDTH }
-      : { url: photo.urls.hd, width: photo.width || SD_WIDTH },
+  hasPano: (photo) =>
+    Boolean(photo.isPano && (photo.urls.sd || hdDecodable(photo))),
+  // Without an SD derivative the original goes straight to the texture size.
+  panoFirst: (photo) => {
+    if (photo.urls.sd) return { url: photo.urls.sd, width: SD_WIDTH };
+    if (!hdDecodable(photo)) return null;
+    const width = Math.min(photo.width, PANO_FULL_SIZE[0]);
+    return { url: photo.urls.hd, width, resize: [width, width / 2] };
+  },
   panoSharp: (photo, size) => {
     const width = photo.width || 0;
     if (!photo.urls.hd || !photo.urls.sd) return null;
@@ -34,8 +49,13 @@ export const PANORAMAX_SOURCES = Object.freeze({
       timeoutMs: HD_TIMEOUT_MS,
     };
   },
-  // A 360° picture shown flat (no WebGL) is its whole equirectangular image.
-  flatFirst: (photo) => [photo.urls.sd, photo.urls.hd, photo.urls.thumb],
+  // A 360° picture shown flat (no WebGL) is its whole equirectangular image;
+  // an original too big to decode is skipped for the thumbnail.
+  flatFirst: (photo) => [
+    photo.urls.sd,
+    !photo.isPano || hdDecodable(photo) ? photo.urls.hd : null,
+    photo.urls.thumb,
+  ],
   flatSharp: (photo, pixels) =>
     photo.urls.sd && photo.urls.hd && pixels > SD_WIDTH ? photo.urls.hd : null,
   describe: (photo) => ({

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

@@ -143,6 +143,7 @@ test('a 360° picture shows its SD equirectangular image, then HD shrunk to 4,09
   assert.deepEqual(loads[0], {
     url: PHOTOS.pano.urls.sd,
     crossOrigin: true,
+    resize: null,
     failure: 'The Panoramax photo could not be loaded',
   });
   assert.equal(poses.at(-1).isPano, true);
@@ -179,8 +180,16 @@ test('HD panoramas too big to decode, or no bigger than SD, are never fetched',
   const hdOnly = { ...PHOTOS.pano, urls: { ...PHOTOS.pano.urls, sd: null } };
   assert.deepEqual(PANORAMAX_SOURCES.panoFirst(hdOnly), {
     url: hdOnly.urls.hd,
-    width: 5760,
+    width: 4096,
+    resize: [4096, 2048],
   });
+  // …unless it is too big to decode: then no panorama, and the thumbnail.
+  const hugeOnly = { ...hdOnly, width: 11_904 };
+  assert.equal(PANORAMAX_SOURCES.panoFirst(hugeOnly), null);
+  assert.equal(PANORAMAX_SOURCES.hasPano(hugeOnly), false);
+  assert.deepEqual(PANORAMAX_SOURCES.flatFirst(hugeOnly).filter(Boolean), [
+    hugeOnly.urls.thumb,
+  ]);
   assert.equal(PANORAMAX_SOURCES.panoSharp(hdOnly, size), null);
   assert.equal(PANORAMAX_SOURCES.flatSharp(PHOTOS.flat, 2048), null);
   assert.equal(

src/tooling/streetLevelQa.test.mjs

@@ -755,12 +755,10 @@ test('Panoramax fixtures: two sequences on one street, searches honour sequence
     panoramaxTile,
     resetPanoramaxFixture,
   } = await import('../../scripts/fixtures/street-level/panoramax.mjs');
-  const { decodeCoverageTile, decodePictures } = await import(
-    '../layers/streetLevel/providers/panoramax/decode.js'
-  );
-  const { normalizeItem } = await import(
-    '../layers/streetLevel/providers/panoramax/policy.js'
-  );
+  const { decodeCoverageTile, decodePictures } =
+    await import('../layers/streetLevel/providers/panoramax/decode.js');
+  const { normalizeItem } =
+    await import('../layers/streetLevel/providers/panoramax/policy.js');
   resetPanoramaxFixture();
   const pictures = panoramaxPictures();
   assert.deepEqual(