fix(street-level): Panoramax IC8 round 2 — shared point budget, selected line, cone cache, DP segments

From the round-2 verification (approve with follow-ups), all follow-ups:
- The point budget is shared across the tiles in view once loading
  settles (water-filling): a sparse tile keeps what it has, a dense city
  centre takes the rest instead of drawing thinner than its suburbs. The
  selected sequence is always drawn, and selecting one a cap had left out
  draws it.
- The cones' picture-list cache keeps only finished lists: a re-centre
  while the cones loaded inherited the aborted load's tiles and drew
  none in them.
- Douglas–Peucker measures to the segment, so dead ends and U-turns keep
  their far end.
- Switching Panoramax off lets its decoded tiles and lists go.
- Picture downloads are counted while they stream (a host sending no
  length cannot fill memory before the cap).
- Comments on the via caption and the simplification tolerance match the
  code.

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

docs/CURRENT-STATE.md

@@ -3256,7 +3256,16 @@ IGN, MapComplete…; IGN's redirect to its OVH object storage). Its chip
 vector tiles (`/api/map/{z}/{x}/{y}.mvt`, an hour's HTTP cache): sequence
 lines from z14 below 1.8 km above ground, z13 to 5 km, z12 to 12 km, z11
 to 30 km and z10 to 60 km, as Mapillary's (a dense z10 tile over Paris is
-~2.1 MB and 8,600 sequences; each tile draws its 1,600 longest), and above
+~2.1 MB and 8,600 sequences, 750,000 points). `decode.js` simplifies each
+line (Douglas–Peucker to the segment, 4 units of a 4,096 tile: about a
+pixel where it is drawn, 6–10% of a GPS track's points), and the tiles in
+view draw their longest lines within 90,000 points (`maxPoints`,
+`keepOrder`), shared out once loading settles so a sparse tile keeps all
+it has and a dense one (a city centre) takes the rest; the selected
+sequence is always drawn. Every point becomes ~8 ground-line vertices:
+unsimplified, the lines hung the tab. Decoded tiles are kept while the
+provider is on (16, ten minutes, `tileCache.js`, shared with KartaView),
+and above
 60 km the `grid` layer's 0.1°
 density cells, binned to at most 96×96 points a tile (a z0 tile holds
 ~70,000 cells) and not counted as sequences: the panel says to zoom in. Both

src/layers/streetLevel/lineCoverage.js

@@ -155,19 +155,85 @@ export function createLineCoverage({
   function drawnSequences(entry) {
     const drawn = [];
     const current = filter();
+    const selectedId = state.sequence.selectedId ?? null;
+    const cap = entry.pointCap ?? perTilePointCap;
     let points = 0;
+    let demand = 0;
     for (const sequence of entry.sequenceList) {
-      if (drawn.length >= perTileSequenceCap) break;
       if (!passes(sequence, current)) continue;
-      // A line past the point budget is skipped; a shorter one may still fit.
       const size = pointsOf(sequence);
-      if (points + size > perTilePointCap) continue;
+      demand += size;
+      // The selected sequence is always drawn: its highlight is the answer
+      // to a click, whatever the caps leave out.
+      if (sequence.id === selectedId) {
+        points += size;
+        drawn.push(sequence);
+        continue;
+      }
+      if (drawn.length >= perTileSequenceCap) continue;
+      // A line past the point budget is skipped; a shorter one may still fit.
+      if (points + size > cap) continue;
       points += size;
       drawn.push(sequence);
     }
+    // What every passing line would take: the budget is shared by it.
+    entry.pointDemand = demand;
+    entry.pointsDrawn = points;
     return drawn;
   }
 
+  /**
+   * Share the point budget across the tiles in view (water-filling): a
+   * sparse tile keeps what it needs and the rest goes to the dense ones,
+   * so a city centre is not drawn thinner than its suburbs. Sets each
+   * tile's cap; returns the tiles whose cap changes what they draw.
+   */
+  function shareCaps() {
+    const changed = [];
+    if (!tuning.maxPoints) return changed;
+    const entries = [...state.coverage.tiles.values()].filter(
+      (entry) => entry.kind === 'sequence',
+    );
+    const byDemand = [...entries].sort(
+      (a, b) => (a.pointDemand || 0) - (b.pointDemand || 0),
+    );
+    let left = tuning.maxPoints;
+    byDemand.forEach((entry, i) => {
+      const share = left / (byDemand.length - i);
+      const cap = Math.floor(Math.min(entry.pointDemand || 0, share));
+      left -= cap;
+      const before = entry.pointCap ?? perTilePointCap;
+      entry.pointCap = cap;
+      // Only a change that alters what is drawn: more room for a tile that
+      // had lines left out, or less than it draws now.
+      if (
+        (cap > before && entry.pointsDrawn < entry.pointDemand) ||
+        cap < entry.pointsDrawn
+      )
+        changed.push(entry);
+    });
+    return changed;
+  }
+
+  /** Once loading settles: redraw the tiles the shared budget changes. */
+  function shareBudget() {
+    const changed = shareCaps();
+    for (const entry of changed) redrawEntry(entry);
+    if (changed.length) {
+      requestRender();
+      notify();
+    }
+  }
+
+  /** Draw one tile again from its decoded lines (caps or selection changed). */
+  function redrawEntry(entry) {
+    cancelCast(entry);
+    entry.castRequested = false;
+    entry.meshParts = null;
+    detachPrimitive(entry);
+    attachPrimitive(entry);
+  }
+
   function pointsOf(sequence) {
     let count = 0;
     for (const part of sequence.parts) count += part.length;
@@ -616,7 +682,10 @@ export function createLineCoverage({
       // must not drop a newer request's entry (which is what counts as loading).
       if (state.coverage.pending.get(key) === controller) {
         state.coverage.pending.delete(key);
-        if (!state.coverage.pending.size) purgeStale();
+        if (!state.coverage.pending.size) {
+          purgeStale();
+          shareBudget();
+        }
       }
       notify();
     }
@@ -809,13 +878,12 @@ export function createLineCoverage({
   /** Rebuild every loaded tile from its decoded cache (after a filter change). */
   function rebuild() {
     purgeStale();
-    for (const entry of state.coverage.tiles.values()) {
-      cancelCast(entry);
-      entry.castRequested = false;
-      entry.meshParts = null;
-      detachPrimitive(entry);
-      attachPrimitive(entry);
-    }
+    // What each tile's lines need under the new filter, then the shares,
+    // then one redraw each.
+    for (const entry of state.coverage.tiles.values())
+      if (entry.kind === 'sequence') drawnSequences(entry);
+    shareCaps();
+    for (const entry of state.coverage.tiles.values()) redrawEntry(entry);
     requestRender();
     notify();
   }
@@ -860,6 +928,15 @@ export function createLineCoverage({
 
   /** Recolour one sequence, every part of it, in place (selection highlight). */
   function recolorSequence(id, selected) {
+    // Selected but left out by a cap: draw it (it is always admitted).
+    if (selected && (tuning.maxPoints || 0) > 0)
+      for (const entry of state.coverage.tiles.values())
+        if (
+          entry.kind === 'sequence' &&
+          !entry.sequences.has(id) &&
+          entry.sequenceList.some((sequence) => sequence.id === id)
+        )
+          redrawEntry(entry);
     for (const entry of drawnEntries()) {
       const sequence = entry.sequences.get(id);
       if (!sequence) continue;

src/layers/streetLevel/lineCoverage.test.mjs

@@ -76,7 +76,7 @@ function setup(
     fetchTile: async (tile) => {
       asked.push(tile);
       if (fail) throw fail;
-      if (decoded) return decoded(centre);
+      if (decoded) return decoded(centre, tile);
       return {
         sequences: [
           {
@@ -247,3 +247,94 @@ test('a point budget skips lines past it, and a shorter one later may still fit'
   const [tile] = state.coverage.tiles.values();
   assert.deepEqual([...tile.sequences.keys()], ['three', 'two']);
 });
+
+/** A line of `n` points, its id unique to the tile. */
+function pointsLine(id, n, tile, centre) {
+  return {
+    id,
+    parts: [
+      Array.from({ length: n }, (_, i) => [
+        centre.lon - 0.001 + i * 0.00001,
+        centre.lat,
+      ]),
+    ],
+    capturedAt: 0,
+    isPano: false,
+  };
+}
+
+test('the point budget is shared: a sparse tile keeps its few, a dense one gets the rest', async (t) => {
+  const tuning = {
+    ...TUNING,
+    maxTiles: 9,
+    maxSequences: 900,
+    maxPoints: 90,
+    keepOrder: true,
+  };
+  const { state, coverage } = setup(t, {
+    // Street zoom far enough in that several tiles are in view.
+    zoomFor: () => ({ zoom: 18, kind: 'sequence' }),
+    tuning,
+    decoded: (centre, tile) => {
+      const dense = tile.x % 2 === 0 && tile.y % 2 === 0;
+      const lines = dense
+        ? Array.from({ length: 30 }, (_, i) =>
+            pointsLine(`d${tile.x}/${tile.y}/${i}`, 5, tile, centre),
+          )
+        : [pointsLine(`s${tile.x}/${tile.y}`, 2, tile, centre)];
+      return { sequences: lines, overview: [] };
+    },
+  });
+  coverage.refresh();
+  assert.ok(
+    await until(
+      () => state.coverage.tiles.size > 1 && !state.coverage.pending.size,
+    ),
+  );
+  const entries = [...state.coverage.tiles.values()];
+  const drawn = (entry) => entry.pointsDrawn;
+  const total = entries.reduce((sum, entry) => sum + drawn(entry), 0);
+  assert.ok(total <= tuning.maxPoints, `within the budget: ${total}`);
+  const sparse = entries.filter((entry) => entry.pointDemand === 2);
+  const dense = entries.filter((entry) => entry.pointDemand === 150);
+  assert.ok(sparse.length && dense.length, 'both kinds in view');
+  for (const entry of sparse)
+    assert.equal(drawn(entry), 2, 'a sparse tile keeps all');
+  const fair = Math.floor(tuning.maxPoints / tuning.maxTiles);
+  const left = tuning.maxPoints - sparse.length * 2;
+  for (const entry of dense)
+    assert.ok(
+      drawn(entry) > fair || dense.length * fair >= left,
+      `a dense tile gets more than the even share: ${drawn(entry)}`,
+    );
+  assert.ok(
+    total > tuning.maxPoints - 5 * dense.length,
+    'little budget unused',
+  );
+});
+
+test('a selected sequence the budget left out is drawn, highlighted', async (t) => {
+  const { state, coverage } = setup(t, {
+    tuning: {
+      ...TUNING,
+      maxTiles: 1,
+      maxSequences: 10,
+      maxPoints: 5,
+      keepOrder: true,
+    },
+    decoded: (centre, tile) => ({
+      sequences: [
+        pointsLine('long', 5, tile, centre),
+        pointsLine('short', 3, tile, centre),
+      ],
+      overview: [],
+    }),
+  });
+  coverage.refresh();
+  assert.ok(await until(() => state.coverage.tiles.size === 1));
+  const [tile] = state.coverage.tiles.values();
+  assert.deepEqual([...tile.sequences.keys()], ['long']);
+  state.sequence.selectedId = 'short';
+  coverage.recolorSequence('short', true);
+  assert.deepEqual([...tile.sequences.keys()].sort(), ['long', 'short']);
+});

src/layers/streetLevel/photoViewer.js

@@ -79,8 +79,7 @@ async function loadBitmap(url, timeoutMs, resize, failure, signal) {
     // photo's size before it is decoded.
     const length = Number(response.headers?.get?.('content-length'));
     if (length > MAX_IMAGE_BYTES) throw new Error(failure);
-    const blob = await response.blob();
-    if (blob.size > MAX_IMAGE_BYTES) throw new Error(failure);
+    const blob = await boundedBlob(response, failure);
     const bitmap = await (resize
       ? createImageBitmap(blob, {
           resizeWidth: resize[0],
@@ -88,6 +87,7 @@ async function loadBitmap(url, timeoutMs, resize, failure, signal) {
           resizeQuality: 'high',
         })
       : createImageBitmap(blob));
+    // (A resized decode reports its new size: this guards unresized ones.)
     if (bitmap.width > MAX_IMAGE_SIDE || bitmap.height > MAX_IMAGE_SIDE) {
       bitmap.close?.();
       throw new Error(failure);
@@ -101,6 +101,34 @@ async function loadBitmap(url, timeoutMs, resize, failure, signal) {
   }
 }
 
+/**
+ * The body as a Blob, read with a running count so a host that sends no
+ * length (or a false one) cannot fill memory before the cap is checked.
+ */
+async function boundedBlob(response, failure) {
+  const reader = response.body?.getReader?.();
+  if (!reader) {
+    const blob = await response.blob();
+    if (blob.size > MAX_IMAGE_BYTES) throw new Error(failure);
+    return blob;
+  }
+  const chunks = [];
+  let total = 0;
+  for (;;) {
+    const { done, value } = await reader.read();
+    if (done) break;
+    total += value.byteLength;
+    if (total > MAX_IMAGE_BYTES) {
+      reader.cancel().catch(() => {});
+      throw new Error(failure);
+    }
+    chunks.push(value);
+  }
+  return new Blob(chunks, {
+    type: response.headers?.get?.('content-type') || 'image/jpeg',
+  });
+}
+
 /** The panorama size a canvas this wide can show sharply at this field of view. */
 export function panoSizeFor(canvasPixels, fovDeg) {
   const needed = (Math.max(1, canvasPixels) * 360) / Math.max(1, fovDeg);

src/layers/streetLevel/photoViewer.test.mjs

@@ -303,6 +303,20 @@ test('a picture file or bitmap past any real photo’s size is refused', async (
   respond({ width: MAX_IMAGE_SIDE + 1 });
   await assert.rejects(loadImage('https://x/a.jpg'), /could not be loaded/);
   assert.equal(closed, 1, 'the oversize bitmap is released');
+  // No length given, a body that keeps coming: cut off while it streams.
+  let pulled = 0;
+  globalThis.fetch = async () => ({
+    ok: true,
+    headers: new Map(),
+    body: new ReadableStream({
+      pull(controller) {
+        pulled++;
+        controller.enqueue(new Uint8Array(8 * 1024 * 1024));
+      },
+    }),
+  });
+  await assert.rejects(loadImage('https://x/a.jpg'), /could not be loaded/);
+  assert.ok(pulled * 8 * 1024 * 1024 <= MAX_IMAGE_BYTES + 16 * 1024 * 1024);
   respond({});
   assert.equal((await loadImage('https://x/a.jpg')).width, 100);
 });

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

@@ -9,7 +9,8 @@ import {
 
 /**
  * Douglas–Peucker in tile units: the points of `line` ({x, y}) that keep
- * it within `tolerance` of the original, first and last always kept.
+ * it within `tolerance` of the original (measured to each segment, so
+ * dead ends and U-turns stay), first and last always kept.
  * Iterative, so a long track cannot overflow the stack.
  */
 export function simplifyLine(line, tolerance) {
@@ -24,15 +25,20 @@ export function simplifyLine(line, tolerance) {
     const b = line[to];
     const dx = b.x - a.x;
     const dy = b.y - a.y;
-    const span = Math.hypot(dx, dy);
+    const span2 = dx * dx + dy * dy;
     let far = -1;
     let farthest = tolerance;
     for (let i = from + 1; i < to; i++) {
       const p = line[i];
-      // Distance to the chord, or to `a` where the chord has no length.
-      const d = span
-        ? Math.abs((p.x - a.x) * dy - (p.y - a.y) * dx) / span
-        : Math.hypot(p.x - a.x, p.y - a.y);
+      // Distance to the segment, not the infinite line: a dead end or a
+      // U-turn (a point beyond the chord's ends) is kept.
+      const t = span2
+        ? Math.max(
+            0,
+            Math.min(1, ((p.x - a.x) * dx + (p.y - a.y) * dy) / span2),
+          )
+        : 0;
+      const d = Math.hypot(p.x - (a.x + t * dx), p.y - (a.y + t * dy));
       if (d > farthest) {
         farthest = d;
         far = i;

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

@@ -216,6 +216,13 @@ test('lines are simplified within a few tile units, ends and corners kept', () =
   ];
   assert.equal(simplifyLine(loop, 4).length, 3);
   assert.equal(simplifyLine(zigzag, 0).length, 1000, 'no tolerance, no change');
+  // A dead end: out to 100 and back to 50 keeps its far end.
+  const deadEnd = [
+    { x: 0, y: 0 },
+    { x: 100, y: 0 },
+    { x: 50, y: 0 },
+  ];
+  assert.deepEqual(simplifyLine(deadEnd, 4), deadEnd);
 });
 
 test('a decoded GPS track keeps a fraction of its points', () => {

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

@@ -286,11 +286,15 @@ export function createPanoramaxProvider({
       });
       /** A z15 tile's pictures of one sequence, by `z/x/y:sequence`. */
       const pictureLists = createLru(PICTURE_LIST_CACHE_SIZE);
-      function picturesIn(tile, sequenceId, signal) {
+      /**
+       * Only finished lists are kept: a load in flight belongs to its own
+       * selection, whose abort (a re-centre) must not empty the next one's.
+       */
+      async function picturesIn(tile, sequenceId, signal) {
         const key = `${tileKey(tile)}:${sequenceId}`;
         const kept = pictureLists.get(key);
         if (kept) return kept;
-        const list = readable(async () =>
+        const list = await readable(async () =>
           decodePictures(
             await source.getTile(tile, { signal, lane: 'pictures' }),
             tile,
@@ -298,7 +302,6 @@ export function createPanoramaxProvider({
           ),
         );
         pictureLists.set(key, list);
-        list.catch(() => pictureLists.delete(key));
         return list;
       }
 
@@ -418,6 +421,9 @@ export function createPanoramaxProvider({
           cones.setVisible(false);
           drawn = null;
           preferred = null;
+          // Off: decoded tiles and lists go (several MB each over a city).
+          coverageTiles.clear();
+          pictureLists.clear();
         },
 
         destroy(cesiumViewer) {

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

@@ -62,8 +62,8 @@ export const COVERAGE_TUNING = Object.freeze({
 });
 /**
  * Lines are simplified (Douglas–Peucker) to this many tile units of a
- * 4,096 extent: under a pixel at every height lines are drawn from, and
- * 6–10% of the points GPS tracks carry.
+ * 4,096 extent: about a pixel where each zoom is drawn (1.6 m at z14,
+ * within GPS noise), and 6–10% of the points GPS tracks carry.
  */
 export const SIMPLIFY_TOLERANCE_UNITS = 4;
 /**
@@ -280,8 +280,8 @@ export function normalizeItem(item) {
     isPano: isEquirectangular(item),
     capturedAt: panoramaxTimeMs(props.datetime),
     creator: creatorOf(item),
-    // Licences ask for the source to be named: the instance holding it is
-    // named beside an author, or alone where the author is hidden.
+    // Licences ask for the source to be named: where no author can be
+    // named, the caption names the instance holding the picture.
     via: instanceOf(item),
     license: licenseLabel(props.license),
     width: Number.isFinite(width) && width > 0 ? width : null,

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

@@ -927,19 +927,89 @@ test('lines keep the decoded (longest-first) order under a budget of points', as
   assert.ok(COVERAGE_TUNING.maxPoints > 0);
 });
 
-test('a coverage tile decoded a moment ago is not fetched or decoded again', async (t) => {
+test('a coverage tile decoded a moment ago is not fetched again; switched off, the tiles are let go', async (t) => {
   const env = coverageSetup(t, { sequences: [line('a')] });
-  let asked = 0;
+  const asked = [];
   const getTile = env.source.getTile;
   env.source.getTile = (tile, options) => {
-    asked++;
+    asked.push(`${tile.z}/${tile.x}/${tile.y}`);
     return getTile(tile, options);
   };
   env.instance.activate(env.viewer);
   assert.ok(await until(() => env.instance.coverageStats().count === 1));
-  const first = asked;
+  const z14 = asked.length;
+  // Up a zoom band and back down: the z14 tile comes from memory.
+  env.viewer.view.height = 3_000;
+  env.instance.refreshCoverage();
+  assert.ok(await until(() => env.instance.coverageStats().zoom === 13));
+  assert.ok(await until(() => !env.instance.coverageStats().loading));
+  const withZ13 = asked.length;
+  env.viewer.view.height = 900;
+  env.instance.refreshCoverage();
+  assert.ok(await until(() => env.instance.coverageStats().zoom === 14));
+  assert.ok(await until(() => env.instance.coverageStats().count === 1));
+  assert.equal(asked.length, withZ13, 'nothing fetched again');
+  assert.ok(z14 > 0);
+  // Off and on: the memory went back, so the tile is fetched again.
   env.instance.deactivate();
   env.instance.activate(env.viewer);
   assert.ok(await until(() => env.instance.coverageStats().count === 1));
-  assert.equal(asked, first);
+  assert.ok(asked.length > withZ13);
+});
+
+test('a re-centre while the cones still load does not inherit the aborted load’s tiles', async (t) => {
+  const items = sequence('long', 400);
+  const tiles = pictureTiles(items);
+  const env = await mounted({ items, tiles });
+  const cones = await withCones(t, env);
+  let hold = null;
+  env.source.getTile = async (tile, { signal } = {}) => {
+    env.source.calls.tiles.push(`${tile.z}/${tile.x}/${tile.y}`);
+    if (hold) await hold.promise;
+    signal?.throwIfAborted();
+    return tiles(tile);
+  };
+  await env.instance.viewer.open('long-0');
+  const tileOf = (item) => {
+    const [lon, lat] = item.geometry.coordinates;
+    return pictureTilesAround({ lon, lat })[0];
+  };
+  const first = new Set(
+    pictureTilesAround({
+      lon: items[0].geometry.coordinates[0],
+      lat: items[0].geometry.coordinates[1],
+    }).map((tile) => `${tile.x}/${tile.y}`),
+  );
+  const out = items.findIndex((item) => {
+    const tile = tileOf(item);
+    return !first.has(`${tile.x}/${tile.y}`);
+  });
+  hold = {};
+  hold.promise = new Promise((resolve) => (hold.release = resolve));
+  const loading = env.instance.selectSequence('long');
+  await new Promise((resolve) => setTimeout(resolve, 5));
+  // The far picture opens while the first load is held: the cones re-centre.
+  await env.instance.viewer.open(`long-${out}`);
+  await new Promise((resolve) => setTimeout(resolve, 5));
+  const release = hold.release;
+  hold = null;
+  release();
+  await loading;
+  assert.ok(await until(() => !env.instance.sequenceStats().loading));
+  // Every picture in the tiles the second load covers has its cone.
+  const [lon, lat] = items[out].geometry.coordinates;
+  const second = new Set(
+    pictureTilesAround({ lon, lat }).map((tile) => `${tile.x}/${tile.y}`),
+  );
+  const ids = new Set(cones.ids());
+  const covered = items.filter((item) => {
+    const tile = tileOf(item);
+    return second.has(`${tile.x}/${tile.y}`);
+  });
+  assert.ok(covered.length > 0);
+  assert.equal(
+    covered.filter((item) => ids.has(item.id)).length,
+    covered.length,
+    'every picture in the re-centred tiles has its cone (the shared ones too)',
+  );
 });

src/layers/streetLevel/tileCache.js

@@ -44,5 +44,7 @@ export function createTileCache({
       kept.set(key, { at: now(), tile: loaded });
       return loaded;
     },
+    /** Forget every tile (the layer is off: its memory goes back). */
+    clear: () => kept.clear(),
   };
 }