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';