refactor(street-level): no sequence image cache; one pose listener

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

src/layers/streetLevel/providers/mapillary/sequences.js

@@ -11,9 +11,6 @@ import {
 
 const SPRITE_ID = 'street-level:mapillary-cones';
 
-/** How many recently viewed sequences keep their image list in memory. */
-const SEQUENCE_CACHE_SIZE = 40;
-
 /** Normalize a graph image record into the shape the cones use. */
 function normalizeSequenceImage(record) {
   const coordinates = record?.geometry?.coordinates;
@@ -115,14 +112,6 @@ export function createSequences({ state, source, parts }) {
     requestRender();
   }
 
-  function remember(sequenceId, images) {
-    const { cache } = state.sequence;
-    cache.delete(sequenceId);
-    cache.set(sequenceId, images);
-    while (cache.size > SEQUENCE_CACHE_SIZE)
-      cache.delete(cache.keys().next().value);
-  }
-
   /** Select a sequence: highlight its line and load its image cones. */
   async function select(sequenceId) {
     if (!sequenceId || !state.viewer) return;
@@ -135,16 +124,6 @@ export function createSequences({ state, source, parts }) {
     state.sequence.abort?.abort();
     state.sequence.selectedId = sequenceId;
     parts.coverage.highlight(sequenceId);
-    const cached = state.sequence.cache.get(sequenceId);
-    if (cached) {
-      state.sequence.abort = null;
-      state.sequence.loading = false;
-      state.sequence.images = cached;
-      renderCones(cached);
-      state.sequence.error = null;
-      notify();
-      return;
-    }
     // The previous sequence's cones must not stay clickable under the new
     // highlight while this one loads, nor after its load fails.
     clearCones();
@@ -164,7 +143,6 @@ export function createSequences({ state, source, parts }) {
           .filter(Boolean)
           .sort((a, b) => a.capturedAt - b.capturedAt),
       );
-      remember(sequenceId, images);
       state.sequence.images = images;
       renderCones(images);
       state.sequence.error = null;

src/layers/streetLevel/providers/mapillary/sequences.test.mjs

@@ -67,7 +67,6 @@ function setup() {
     sequence: {
       selectedId: null,
       images: [],
-      cache: new Map(),
       collection: cones(),
       loading: false,
       error: null,
@@ -112,7 +111,7 @@ test('a failed sequence load leaves no stale cones and can be retried', async ()
   assert.equal(state.sequence.error, null, 'cleared once B loads');
 });
 
-test('a late answer for a superseded sequence neither draws nor is cached', async () => {
+test('a late answer for a superseded sequence draws nothing', async () => {
   const { state, source, sequences, drawn } = setup();
   sequences.select('A');
   sequences.select('B');
@@ -123,7 +122,6 @@ test('a late answer for a superseded sequence neither draws nor is cached', asyn
   await settle();
   assert.deepEqual(drawn(), ['B-0', 'B-1']);
   assert.equal(state.sequence.selectedId, 'B');
-  assert.equal(state.sequence.cache.has('A'), false);
   assert.equal(state.sequence.loading, false);
 });
 
@@ -135,21 +133,6 @@ test('a second click on a loading sequence does not start another lookup', async
   assert.equal(source.calls[0].signal.aborted, false);
 });
 
-test('a cached sequence is re-selected without a lookup', async () => {
-  const { state, source, sequences, drawn } = setup();
-  sequences.select('A');
-  source.last('A').resolve(records('A'));
-  await settle();
-  sequences.select('B');
-  source.last('B').resolve(records('B'));
-  await settle();
-  sequences.select('A');
-  assert.equal(source.calls.length, 2, 'A came from the cache');
-  assert.deepEqual(drawn(), ['A-0', 'A-1'], 'drawn at once');
-  assert.equal(state.sequence.loading, false);
-  assert.equal(state.sequence.selectedId, 'A');
-});
-
 test('clearSelection cancels the lookup and drops the highlight', async () => {
   const { state, source, sequences, highlights, drawn } = setup();
   sequences.select('A');

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

@@ -27,7 +27,8 @@ export function createMapillaryViewer({ source, render } = {}) {
   let renderMode = 'letterbox';
   /** Metadata of the image on screen; pov/position events reuse it. */
   let current = null;
-  const listeners = new Set();
+  /** The pose listener (the viewer host); one at a time. */
+  let poseListener = null;
 
   function requestRender() {
     render?.governorRequestRender?.('mapillary-viewer');
@@ -52,12 +53,10 @@ export function createMapillaryViewer({ source, render } = {}) {
   }
 
   function emit(pose) {
-    for (const listener of [...listeners]) {
-      try {
-        listener(pose);
-      } catch {
-        /* listener errors are the core's to log */
-      }
+    try {
+      poseListener?.(pose);
+    } catch {
+      /* listener errors are the core's to log */
     }
   }
 
@@ -201,8 +200,10 @@ export function createMapillaryViewer({ source, render } = {}) {
     },
 
     onPose(listener) {
-      listeners.add(listener);
-      return () => listeners.delete(listener);
+      poseListener = listener;
+      return () => {
+        if (poseListener === listener) poseListener = null;
+      };
     },
   };
 }

src/layers/streetLevel/state.js

@@ -71,8 +71,6 @@ export function createState({ services }) {
     sequence: {
       selectedId: null,
       images: [],
-      /** Recent sequences' thinned images, by sequence id. */
-      cache: new Map(),
       collection: null,
       loading: false,
       /** Why the selected sequence's images could not load, until it goes. */