Use a neutral compact switch codec and clarify provider size limits

src/data/idSwitches.js

@@ -0,0 +1,47 @@
+const MAX_SWITCHES_LENGTH = 256;
+const ENTRY = /^([a-z][a-z0-9-]*)-([01])$/;
+
+/** Canonical, bounded boolean switches keyed by stable slugs. */
+export function normalizeIdSwitches(value, reservedIds = []) {
+  if (typeof value !== 'string' || value.length > MAX_SWITCHES_LENGTH)
+    return null;
+  if (!value) return '';
+  const entries = new Map();
+  for (const field of value.split('*')) {
+    const match = ENTRY.exec(field);
+    if (!match || reservedIds.includes(match[1]) || entries.has(match[1]))
+      return null;
+    entries.set(match[1], match[2] === '1');
+  }
+  return [...entries]
+    .sort(([a], [b]) => (a < b ? -1 : a > b ? 1 : 0))
+    .map(([id, on]) => `${id}-${on ? '1' : '0'}`)
+    .join('*');
+}
+
+/** Encode by stable IDs rather than registration order or generated tokens. */
+export function encodeIdSwitches(switches) {
+  const value = [...switches]
+    .map(([id, on]) => `${id}-${on === true ? '1' : '0'}`)
+    .join('*');
+  if (value.length > MAX_SWITCHES_LENGTH)
+    throw new RangeError(
+      `Switch IDs exceed the ${MAX_SWITCHES_LENGTH}-character share-link limit`,
+    );
+  const normalized = normalizeIdSwitches(value);
+  if (normalized === null) throw new TypeError('Invalid boolean switch IDs');
+  return normalized;
+}
+
+/** A Map keeps switch IDs separate from object prototype properties. */
+export function decodeIdSwitches(value) {
+  const normalized = normalizeIdSwitches(value);
+  return new Map(
+    normalized
+      ? normalized.split('*').map((entry) => {
+          const [, id, on] = ENTRY.exec(entry);
+          return [id, on === '1'];
+        })
+      : [],
+  );
+}

src/data/layerState.js

@@ -1,4 +1,4 @@
-import { normalizeProviderSwitches } from '../layers/streetLevel/providerSwitches.js';
+import { normalizeIdSwitches } from './idSwitches.js';
 import reservationRows from './layerStateTokenReservations.json' with { type: 'json' };
 
 const VALID_DISPOSITIONS = new Set([
@@ -418,9 +418,9 @@ const OPTION_GROUPS = Object.freeze({
       key: 'providerSwitches',
       token: 'r',
       defaultValue: '',
-      normalize: normalizeProviderSwitches,
-      encode: normalizeProviderSwitches,
-      decode: normalizeProviderSwitches,
+      normalize: (value) => normalizeIdSwitches(value, ['mapillary']),
+      encode: normalizeIdSwitches,
+      decode: (value) => normalizeIdSwitches(value, ['mapillary']),
     }),
     enumOption('pano', 'p', 'all', ['all', 'pano', 'flat'], {
       all: 'a',

src/data/layerStateTokenLedger.test.mjs

@@ -98,16 +98,11 @@ function withPublishedBase(
 }
 
 function writeCodecFixture(cwd, rows, entries) {
-  const providerCodec = path.join(
-    cwd,
-    'src/layers/streetLevel/providerSwitches.js',
-  );
+  const providerCodec = path.join(cwd, 'src/data/idSwitches.js');
   mkdirSync(path.dirname(providerCodec), { recursive: true });
   writeFileSync(
     providerCodec,
-    readFileSync(
-      new URL('../layers/streetLevel/providerSwitches.js', import.meta.url),
-    ),
+    readFileSync(new URL('./idSwitches.js', import.meta.url)),
   );
   const source = readFileSync(CODEC_SOURCE_PATH, 'utf8');
   const registryEnd = ']);\n\nexport const REGISTERED_LAYER_IDS';

src/layers/streetLevel/params.js

@@ -1,8 +1,5 @@
 import { normalizeFilter } from './filter.js';
-import {
-  encodeProviderSwitches,
-  decodeProviderSwitches,
-} from './providerSwitches.js';
+import { encodeIdSwitches, decodeIdSwitches } from '../../data/idSwitches.js';
 
 /**
  * Provider params plus the filter. Custom switches share a stable ID-based
@@ -13,7 +10,9 @@ export function encodeParams({ providers, filter }) {
   const params = {};
   const entries = [...providers];
   for (const [id, on] of entries) params[id] = on === true;
-  const switches = encodeProviderSwitches(entries);
+  const switches = encodeIdSwitches(
+    entries.filter(([id]) => id !== 'mapillary'),
+  );
   if (switches) params.providerSwitches = switches;
   params.pano = filter.pano;
   params.sinceDays = filter.sinceDays;
@@ -30,7 +29,8 @@ export function encodeParams({ providers, filter }) {
 export function decodeParams(params, { providerIds, filter }) {
   const providers = new Map();
   const source = params && typeof params === 'object' ? params : {};
-  const switches = decodeProviderSwitches(source.providerSwitches);
+  const switches = decodeIdSwitches(source.providerSwitches);
+  switches.delete('mapillary');
   for (const id of providerIds) {
     if (switches.has(id)) providers.set(id, switches.get(id));
     else if (Object.hasOwn(source, id) && typeof source[id] === 'boolean')

src/layers/streetLevel/params.test.mjs

@@ -14,7 +14,7 @@ test('encodeParams writes one boolean per provider plus the filter', () => {
     {
       mapillary: true,
       panoramax: false,
-      providerSwitches: 'panoramax=0',
+      providerSwitches: 'panoramax-0',
       pano: 'flat',
       sinceDays: 365,
     },

src/layers/streetLevel/providerSwitches.js

@@ -1,45 +0,0 @@
-const MAX_SWITCHES_LENGTH = 256;
-const ENTRY = /^([a-z][a-z0-9-]*)=([01])$/;
-
-/** Canonical, bounded provider switches; Mapillary retains its legacy token. */
-export function normalizeProviderSwitches(value) {
-  if (typeof value !== 'string' || value.length > MAX_SWITCHES_LENGTH)
-    return null;
-  if (!value) return '';
-  const entries = new Map();
-  for (const field of value.split(',')) {
-    const match = ENTRY.exec(field);
-    if (!match || match[1] === 'mapillary' || entries.has(match[1]))
-      return null;
-    entries.set(match[1], match[2] === '1');
-  }
-  return [...entries]
-    .sort(([a], [b]) => (a < b ? -1 : a > b ? 1 : 0))
-    .map(([id, on]) => `${id}=${on ? '1' : '0'}`)
-    .join(',');
-}
-
-/** Encode by stable IDs rather than registration order or generated tokens. */
-export function encodeProviderSwitches(providers) {
-  const value = [...providers]
-    .filter(([id]) => id !== 'mapillary')
-    .map(([id, on]) => `${id}=${on === true ? '1' : '0'}`)
-    .join(',');
-  const normalized = normalizeProviderSwitches(value);
-  if (normalized === null)
-    throw new TypeError('Invalid or oversized Street Level provider switches');
-  return normalized;
-}
-
-/** A Map keeps provider IDs separate from object prototype properties. */
-export function decodeProviderSwitches(value) {
-  const normalized = normalizeProviderSwitches(value);
-  return new Map(
-    normalized
-      ? normalized.split(',').map((entry) => {
-          const [id, on] = entry.split('=');
-          return [id, on === '1'];
-        })
-      : [],
-  );
-}

src/layers/streetLevel/providerSwitches.test.mjs

@@ -2,9 +2,10 @@ import test from 'node:test';
 import assert from 'node:assert/strict';
 import { encodeParams, decodeParams } from './params.js';
 import {
-  normalizeProviderSwitches,
-  encodeProviderSwitches,
-} from './providerSwitches.js';
+  normalizeIdSwitches,
+  decodeIdSwitches,
+  encodeIdSwitches,
+} from '../../data/idSwitches.js';
 import {
   createDefaultLayerState,
   encodeLayerStateParams,
@@ -24,7 +25,7 @@ test('custom switches survive sharing and storage without depending on provider
     ['mapillary', false],
   ];
   const options = encodeParams({ providers, filter });
-  assert.equal(options.providerSwitches, 'example=1,panoramax=0');
+  assert.equal(options.providerSwitches, 'example-1*panoramax-0');
   assert.equal(
     encodeParams({ providers: [...providers].reverse(), filter })
       .providerSwitches,
@@ -36,7 +37,11 @@ test('custom switches survive sharing and storage without depending on provider
   const params = new URLSearchParams({ v: '2' });
   encodeLayerStateParams(params, state);
   assert.match(params.get('lo'), /0\.m\.0/);
-  assert.match(params.get('lo'), /0\.r\.example=1,panoramax=0/);
+  assert.match(params.get('lo'), /0\.r\.example-1\*panoramax-0/);
+  assert.ok(
+    params.toString().includes('0.r.example-1*panoramax-0'),
+    'custom switches need no percent escaping',
+  );
   for (const restored of [
     decodeLayerStateParams(params),
     parseStoredLayerState(serializeStoredLayerState(state)),
@@ -91,31 +96,44 @@ test('legacy links retain Mapillary semantics and leave custom defaults alone',
 
 test('switches reject ambiguous or oversized fields and cannot override the legacy token', () => {
   for (const value of [
-    'example=0,example=1',
-    'mapillary=0',
-    '__proto__=1',
-    'a=2',
-    'a=1,',
-    'a.b=1',
-    'a_b=0',
-    `${'a'.repeat(255)}=1`,
+    'example-0*example-1',
+    'mapillary-0',
+    '__proto__-1',
+    'a-2',
+    'a-1*',
+    'a.b-1',
+    'a_b-0',
+    `${'a'.repeat(255)}-1`,
     null,
     {},
   ]) {
-    assert.equal(normalizeProviderSwitches(value), null);
+    assert.equal(normalizeIdSwitches(value, ['mapillary']), null);
   }
-  assert.equal(normalizeProviderSwitches('constructor=0'), 'constructor=0');
+  assert.equal(normalizeIdSwitches('constructor-0'), 'constructor-0');
   assert.throws(
-    () => encodeProviderSwitches([['a'.repeat(255), true]]),
-    /oversized/,
+    () => encodeIdSwitches([['a'.repeat(255), true]]),
+    /share-link/,
   );
   assert.throws(
     () => validateProviders([fakeStreetLevelProvider({ id: 'a'.repeat(255) })]),
-    /oversized/,
+    /share-link/,
   );
   const decoded = decodeParams(
-    { providerSwitches: 'mapillary=0', mapillary: true },
+    { providerSwitches: 'mapillary-0', mapillary: true },
     { providerIds: ['mapillary'], filter },
   );
   assert.equal(decoded.providers.get('mapillary'), true);
 });
+
+test('neutral switch codec preserves hyphens and numeric suffixes in IDs', () => {
+  const switches = [
+    ['provider-0', false],
+    ['provider-1', true],
+    ['a-b-c', true],
+  ];
+  const encoded = encodeIdSwitches(switches);
+  assert.equal(encoded, 'a-b-c-1*provider-0-0*provider-1-1');
+  const decoded = decodeIdSwitches(encoded);
+  for (const [id, on] of switches) assert.equal(decoded.get(id), on);
+  assert.equal(decodeIdSwitches('valid-1*broken').size, 0);
+});

src/layers/streetLevel/registry.js

@@ -1,4 +1,4 @@
-import { encodeProviderSwitches } from './providerSwitches.js';
+import { encodeIdSwitches } from '../../data/idSwitches.js';
 
 /**
  * The contract an imagery provider registers with the Street Level layer.
@@ -128,7 +128,18 @@ export function validateProviders(providers) {
     prefixes.push(provider.pickPrefix);
   }
   // Validate the complete bounded share field once, before any instance exists.
-  encodeProviderSwitches(providers.map(({ id }) => [id, true]));
+  try {
+    encodeIdSwitches(
+      providers
+        .filter(({ id }) => id !== 'mapillary')
+        .map(({ id }) => [id, true]),
+    );
+  } catch (error) {
+    if (!(error instanceof RangeError)) throw error;
+    throw new RangeError(
+      'Street Level provider IDs cannot fit in the 256-character share-link field; use shorter IDs or fewer providers',
+    );
+  }
   return Object.freeze([...providers]);
 }