fix(transit): read Rio speeds as the m/s SMTR publishes

Both SMTR feeds now publish Position.speed in m/s. Compared with how far
vehicles moved between reports on 2026-11-05, the published values ran
3.1x (buses) and 3.6x (BRT) below the observed speed, so the km/h
conversion divided real speeds by 3.6. Drop speedUnit and the conversion.

src/data/transitFeeds.js

@@ -398,12 +398,7 @@ function rioRouteLabel(routeId) {
  *   url: string, headers?: Record<string, string>,
  *   license: string, licenseUrl: string, attribution: string,
  *   defaultMode: string, routeMode?: (routeId: string|null) => string,
- *   speedUnit?: 'kmh',
  * }>>}
- *
- * `speedUnit: 'kmh'` marks a feed that publishes `Position.speed` in km/h
- * instead of the m/s the spec requires; the proxy converts it before anything
- * downstream reads `speedMps`.
  */
 export const TRANSIT_FEED_REGISTRY = Object.freeze([
   Object.freeze({
@@ -765,10 +760,9 @@ export const TRANSIT_FEED_REGISTRY = Object.freeze([
     terms: Object.freeze({
       quote:
         'This work is licensed under a Creative Commons Attribution 4.0 International License',
-      note: 'The data.rio catalog page labels the feed [beta] and states a gateway limit of 5 requests a second and 60 a minute behind a 10-second cache, which the 15-second proxy TTL stays inside. It is the named replacement for the JSON GPS endpoints SMTR deprecated on 2026-10-07 and says it will switch off by 2026-11-30. SMTR relays the concessionaires’ ITS data and repairs trips with its own matching; the page places accuracy with the suppliers. Speeds arrive in km/h, not m/s (a 2026-10-29 snapshot peaked at 89), hence `speedUnit`. Route ids are internal keys (`O0731AAN0A` is line SN731) and are joined to the line names in SMTR’s published GTFS `routes.txt`, under the same CC BY 4.0 terms.',
+      note: 'The data.rio catalog page labels the feed [beta] and states a gateway limit of 5 requests a second and 60 a minute behind a 10-second cache, which the 15-second proxy TTL stays inside. It is the named replacement for the JSON GPS endpoints SMTR deprecated on 2026-10-07 and says it will switch off by 2026-11-30. SMTR relays the concessionaires’ ITS data and repairs trips with its own matching; the page places accuracy with the suppliers. Speeds are m/s, as the spec requires: on 2026-11-05 they matched how far vehicles moved between reports, though a 2026-10-29 snapshot read as km/h. Route ids are internal keys (`O0731AAN0A` is line SN731) and are joined to the line names in SMTR’s published GTFS `routes.txt`, under the same CC BY 4.0 terms.',
     }),
     defaultMode: 'bus',
-    speedUnit: 'kmh',
     routeLabel: rioRouteLabel,
   }),
   Object.freeze({
@@ -788,10 +782,9 @@ export const TRANSIT_FEED_REGISTRY = Object.freeze([
     terms: Object.freeze({
       quote:
         'This work is licensed under a Creative Commons Attribution 4.0 International License',
-      note: 'Same catalog terms, [beta] label and gateway limits as the bus feed. The fleet is operated by Mobi-Rio and tracked by SONDA, whose data SMTR relays. Speeds are km/h here too (peak 62 in the same snapshot). Route ids are opaque (`20000501110` is line 50) and are joined to the same `routes.txt` as the buses.',
+      note: 'Same catalog terms, [beta] label and gateway limits as the bus feed. The fleet is operated by Mobi-Rio and tracked by SONDA, whose data SMTR relays. Speeds are m/s here too. Route ids are opaque (`20000501110` is line 50) and are joined to the same `routes.txt` as the buses.',
     }),
     defaultMode: 'bus',
-    speedUnit: 'kmh',
     routeLabel: rioRouteLabel,
   }),
 ]);

src/data/transitFeeds.test.mjs

@@ -535,14 +535,13 @@ test('the Rio route table is a clean join of published keys to names', () => {
   }
 });
 
-test('Rio feeds are CC BY 4.0, live, and declare the km/h speeds they publish', () => {
+test('Rio feeds are CC BY 4.0 and live', () => {
   for (const id of ['smtr-rio-onibus', 'smtr-rio-brt']) {
     const feed = getTransitFeed(id);
     assert.equal(feed.defaultEnabled, true, `${id} is live`);
     assert.equal(feed.license, 'CC BY 4.0');
     assert.match(feed.licenseUrl, /^https:\/\/www\.data\.rio\/documents\//);
     assert.match(feed.attribution, /Prefeitura da Cidade do Rio de Janeiro/);
-    assert.equal(feed.speedUnit, 'kmh', `${id} publishes km/h`);
     assert.equal(transitModeFor(feed, null), 'bus');
   }
   const sources = readFileSync(

src/data/transitProxy.js

@@ -224,25 +224,6 @@ export function repairVehicleTimestamps(vehicles, headerTimestamp, fetchedAtS) {
   });
 }
 
-/**
- * Bring a feed's speeds to the m/s the spec requires. A feed registered with
- * `speedUnit: 'kmh'` publishes km/h in `Position.speed`, and read as m/s a
- * 44 km/h bus would be reported at 158 km/h. Converting here, once, keeps every
- * consumer of `speedMps` honest without each one knowing about the feed.
- *
- * @param {object} feed Registry entry.
- * @param {object[]} vehicles Normalized vehicle records.
- * @returns {object[]}
- */
-export function normalizeFeedSpeeds(feed, vehicles) {
-  if (feed?.speedUnit !== 'kmh') return vehicles;
-  return vehicles.map((vehicle) =>
-    Number.isFinite(vehicle.speedMps)
-      ? { ...vehicle, speedMps: vehicle.speedMps / 3.6 }
-      : vehicle,
-  );
-}
-
 /**
  * Decode upstream bytes into the JSON snapshot the browser consumes.
  *
@@ -276,7 +257,7 @@ export function buildTransitSnapshot(feed, bytes, now = Date.now()) {
     truncated: decoded.truncated,
     count: decoded.vehicles.length,
     vehicles: repairVehicleTimestamps(
-      normalizeFeedSpeeds(feed, decoded.vehicles),
+      decoded.vehicles,
       decoded.timestamp,
       Math.floor(now / 1000),
     ),

src/data/transitProxy.test.mjs

@@ -285,29 +285,14 @@ test('the snapshot builder fills timestamps from the header it decoded', () => {
   assert.equal(snapshot.feedTimestamp, 1_700_000_000);
 });
 
-test('a feed that publishes km/h has its speeds converted to m/s, and only that feed', () => {
-  // Rio's SMTR feeds put km/h in Position.speed; read as m/s, a 36 km/h bus
-  // would be reported at 130 km/h.
+test('Rio speeds pass through as the m/s they are published in', () => {
+  // SMTR publishes m/s, as the spec requires: checked against how far
+  // vehicles moved between reports on 2026-11-05.
   const bytes = encodeFeed({
-    entities: [
-      { id: 'moving', lat: -22.9, lon: -43.2, speed: 36 },
-      { id: 'still', lat: -22.9, lon: -43.2, speed: 0 },
-      { id: 'silent', lat: -22.9, lon: -43.2 },
-    ],
+    entities: [{ id: 'moving', lat: -22.9, lon: -43.2, speed: 10 }],
   });
   const rio = buildTransitSnapshot(getTransitFeed('smtr-rio-onibus'), bytes, 1);
-  const speeds = Object.fromEntries(
-    rio.vehicles.map((vehicle) => [vehicle.id, vehicle.speedMps]),
-  );
-  assert.ok(Math.abs(speeds.moving - 10) < 1e-6, '36 km/h is 10 m/s');
-  assert.equal(speeds.still, 0);
-  assert.equal(speeds.silent, null, 'an absent speed stays absent');
-  const mbta = buildTransitSnapshot(getTransitFeed('mbta'), bytes, 1);
-  assert.equal(
-    mbta.vehicles.find((vehicle) => vehicle.id === 'moving').speedMps,
-    36,
-    'a spec-conforming feed is left alone',
-  );
+  assert.equal(rio.vehicles[0].speedMps, 10);
 });
 
 test('conditional-request validators and gzip ride along with feed identification', () => {