fix(street-level): a photo that fails to open opens the panel too

With the panel collapsed (the layer switched on from DATA LAYERS no longer
opens it), a line or ground click whose lookup failed — KartaView timing out
or answering 503, no Street View within 50 m — left its error inside the
collapsed panel: the click seemed to do nothing. A new open error now opens
the panel, unstored, as a photo opening does.

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

changelog.d/1241-street-level-panel-cuts.md

@@ -1,4 +1,5 @@
 - Street Level panel: SINCE is a dropdown of its nine windows (the tooltip
   names the cut-off date), IMAGERY and FIT / FILL are plain toggle buttons,
-  and the panel opens by itself only when a photo opens, no longer when the
-  layer is switched on. FIT / FILL starts at FIT each session (gekh, #1241).
+  and the panel opens by itself only when a photo opens or fails to, no
+  longer when the layer is switched on. FIT / FILL starts at FIT each
+  session (gekh, #1241).

docs/CURRENT-STATE.md

@@ -3539,8 +3539,8 @@ image; FIT/FILL starts at FIT each session. IMAGERY and FIT/FILL are rows of
 toggle buttons (`aria-pressed`), each its own tab stop. SINCE is a select of
 the nine windows; a link's day count between them gets its own option, and
 the tooltip names the cut-off date. The panel opens by itself only when a
-photo opens (a click on the map or a line would otherwise load it out of
-sight), never when the layer is switched on.
+photo opens or fails to (a click on the map or a line would otherwise load
+it, or its error, out of sight), never when the layer is switched on.
 
 MapillaryJS loads on the first photo. Opening one frames it with a single
 camera flight through the application's deferred navigation (`begin` /

src/ui/streetLevelControls.js

@@ -29,6 +29,8 @@ export class StreetLevelControls {
     this._state = null;
     this._view = null;
     this._wasOpen = false;
+    /** The open error last shown, so the same one never reopens the panel. */
+    this._streetError = null;
     /** The SINCE option for a day count between the stops, while one is set. */
     this._customSince = null;
     this._resizeQueued = false;
@@ -430,16 +432,21 @@ export class StreetLevelControls {
   }
 
   /**
-   * Open the panel when an image opens (a click on the map or a line would
-   * otherwise load it out of sight). Never persisted: the stored collapse
-   * state stays the user's own choice.
+   * Open the panel when an image opens, or fails to (a click on the map or a
+   * line would otherwise load it, or its error, out of sight). Never
+   * persisted: the stored collapse state stays the user's own choice.
    */
   _reactToTransitions(view) {
     // Other size changes reach the viewer through the ResizeObserver; opening
     // asks for one resize because the element may not have a size yet.
     const open = view.viewer.open;
-    if (open && !this._wasOpen) this.setCollapsed(false, { persist: false });
+    // A photo that failed to open (a line or ground click, OPEN) says why in
+    // the panel: it opens for that too, or the click would seem to do nothing.
+    const error = this._state?.street?.error || null;
+    if ((open && !this._wasOpen) || (error && error !== this._streetError))
+      this.setCollapsed(false, { persist: false });
     this._wasOpen = open;
+    this._streetError = error;
   }
 
   destroy() {

src/ui/streetLevelControls.test.mjs

@@ -425,6 +425,7 @@ function uiState({
   sinceDays = 0,
   renderMode = 'letterbox',
   keyRequired = false,
+  streetError = null,
 } = {}) {
   return {
     enabled,
@@ -439,7 +440,7 @@ function uiState({
       loading: false,
       renderMode,
       imageId: open ? 'img-1' : null,
-      error: null,
+      error: streetError,
     },
   };
 }
@@ -787,6 +788,21 @@ test('a photo opening opens the panel, unstored; switching the layer on does not
     controls.destroy();
   }));
 
+test('a photo that fails to open opens the panel too, so its error shows', () =>
+  withDom(async (dom) => {
+    const { layer, calls, controls } = stubPanel(dom, uiState());
+    // A line click whose lookup KartaView never answered.
+    layer.publish(uiState({ streetError: 'KartaView did not answer in time' }));
+    assert.deepEqual(calls.collapsed, [[false, { persist: false }]]);
+    // The same error again opens nothing more; a new one does.
+    layer.publish(uiState({ streetError: 'KartaView did not answer in time' }));
+    assert.equal(calls.collapsed.length, 1);
+    layer.publish(uiState());
+    layer.publish(uiState({ streetError: 'No street-level imagery here' }));
+    assert.equal(calls.collapsed.length, 2);
+    controls.destroy();
+  }));
+
 test('FIT / FILL show the selected render mode (P3)', () =>
   withDom(async (dom) => {
     const { layer, controls } = stubPanel(dom, uiState({ open: true }));