fix(transit): name and record the backend that answered, not always Transitous

With Google as the transit provider, the result list still credited
Transitous, and a route added from the panel or through
create_transit_journey was saved with provider 'transitous'. The panel
now credits "Google Maps" (untranslated, as Google's terms ask) or
Transitous after the backend that answered and saves that one; the MCP
journey records the backend that plans routes for the caller, and
search_transit_routes reports it.

client/src/components/Planner/TransitSearchPanel.test.tsx

@@ -138,6 +138,34 @@ describe('TransitSearchPanel', () => {
     expect(payload.metadata.transit.legs[1]).toMatchObject({ mode: 'SUBWAY', line: 'U2', line_color: '#FF3300', headsign: 'Ruhleben' })
   })
 
+  it('FE-PLANNER-TRANSIT-003b: routes Google answered name Google Maps and are saved as Google’s (#2850)', async () => {
+    const user = userEvent.setup()
+    const onAdd = vi.fn().mockResolvedValue({})
+    transitApiMock.plan.mockResolvedValueOnce({ itineraries: [ITINERARY], provider: 'google' })
+    render(<TransitSearchPanel {...makeProps({ onAdd })} />)
+    await pickFromAndTo(user)
+    await user.click(screen.getByRole('button', { name: /^Search$/ }))
+    await user.click(await screen.findByText(/08:30 – 09:00/))
+
+    // Google's terms want the words as written, so the browser must not translate them.
+    expect(screen.getByText('Google Maps')).toHaveAttribute('translate', 'no')
+    expect(screen.queryByRole('link', { name: 'Transitous' })).not.toBeInTheDocument()
+
+    await user.click(await screen.findByRole('button', { name: 'Add to day' }))
+    await waitFor(() => expect(onAdd).toHaveBeenCalled())
+    expect(onAdd.mock.calls[0][0].metadata.transit.provider).toBe('google')
+  })
+
+  it('FE-PLANNER-TRANSIT-003c: routes Transitous answered credit Transitous with its sources link', async () => {
+    const user = userEvent.setup()
+    transitApiMock.plan.mockResolvedValueOnce({ itineraries: [ITINERARY], provider: 'transitous' })
+    render(<TransitSearchPanel {...makeProps()} />)
+    await pickFromAndTo(user)
+    await user.click(screen.getByRole('button', { name: /^Search$/ }))
+    expect(await screen.findByRole('link', { name: 'Transitous' })).toHaveAttribute('href', 'https://transitous.org/sources/')
+    expect(screen.queryByText('Google Maps')).not.toBeInTheDocument()
+  })
+
   it('FE-PLANNER-TRANSIT-004: search failure shows the empty state, not a crash', async () => {
     const user = userEvent.setup()
     transitApiMock.plan.mockRejectedValueOnce(new Error('boom'))

client/src/components/Planner/TransitSearchPanel.tsx

@@ -604,7 +604,7 @@ export default function TransitSearchPanel({ day, days, places, accommodations =
         notes: null,
         metadata: {
           transit: {
-            provider: 'transitous',
+            provider: provider ?? 'transitous',
             duration: it.duration,
             transfers: it.transfers,
             walk_seconds: it.walkSeconds,
@@ -760,7 +760,10 @@ export default function TransitSearchPanel({ day, days, places, accommodations =
             ))}
             <div className="text-content-faint" style={{ fontSize: 'calc(10.5px * var(--fs-scale-caption, 1))', textAlign: 'center', marginTop: 2 }}>
               {t('transit.attribution')}{' '}
-              <a href="https://transitous.org/sources/" target="_blank" rel="noopener noreferrer" style={{ color: 'inherit', textDecoration: 'underline' }}>Transitous</a>
+              {/* Named after the backend that answered; Google's terms want "Google Maps" as written, never translated. */}
+              {provider === 'google'
+                ? <span translate="no">Google Maps</span>
+                : <a href="https://transitous.org/sources/" target="_blank" rel="noopener noreferrer" style={{ color: 'inherit', textDecoration: 'underline' }}>Transitous</a>}
             </div>
           </div>
         )}

server/src/nest/transit/transit-itinerary.helpers.ts

@@ -11,6 +11,7 @@ import { haversineKm } from '../common/geo';
 import { localParts, resolveTimeZone } from '../common/timezoneService';
 import type { EndpointInput } from '../reservations/reservations.service';
 import { deriveTransitStats, type TransitItinerary, type TransitLeg } from './transit.helpers';
+import type { TransitProvider } from '@trek/shared';
 
 import { z } from 'zod';
 
@@ -205,10 +206,12 @@ function timezoneAt(lat: number, lng: number): string {
   return timezone;
 }
 
+/** `provider` is the backend the itinerary came from, recorded with the journey. */
 export function buildTransitReservationParts(
   from: TransitPlaceInput,
   to: TransitPlaceInput,
   itinerary: TransitItinerary,
+  provider: TransitProvider,
 ) {
   // The same stop appears up to three times below (transfer endpoint + the
   // adjacent legs' metadata) — memoise the tz lookup per coordinate pair.
@@ -276,7 +279,7 @@ export function buildTransitReservationParts(
   const stats = deriveTransitStats(itinerary.startTime, itinerary.endTime, itinerary.legs, itinerary.transfers);
   const metadata = {
     transit: {
-      provider: 'transitous',
+      provider,
       duration: stats.duration,
       transfers: stats.transfers,
       walk_seconds: stats.walkSeconds,

server/src/nest/transit/transit.mcp.ts

@@ -110,7 +110,7 @@ export class TransitMcp {
   @Tool({
     name: 'search_transit_routes',
     description:
-      'Search scheduled public-transit routes between two coordinates, via whichever backend the instance is configured for. Returns itineraries that can be passed unchanged to create_transit_journey. `dropped` counts provider itineraries that failed validation and are therefore absent from the results — a non-zero value means the provider offered routes this tool could not represent.',
+      'Search scheduled public-transit routes between two coordinates, via whichever backend the instance is configured for. Returns itineraries that can be passed unchanged to create_transit_journey, and `provider`, the backend that answered. `dropped` counts provider itineraries that failed validation and are therefore absent from the results — a non-zero value means the provider offered routes this tool could not represent.',
     inputSchema: {
       from: transitPlaceInput,
       to: transitPlaceInput,
@@ -169,7 +169,7 @@ export class TransitMcp {
       // A rejected itinerary is provider data we could not vouch for, but dropping it
       // silently is indistinguishable from "no routes exist" — report the count so the
       // caller knows the difference.
-      return ok({ itineraries, dropped: result.itineraries.length - itineraries.length });
+      return ok({ itineraries, dropped: result.itineraries.length - itineraries.length, provider: result.provider });
     } catch (err) {
       return errorResult(err, 'Transit route search failed.');
     }
@@ -228,9 +228,11 @@ export class TransitMcp {
         isError: true,
       };
     }
+    // The itinerary came from search_transit_routes, which the active backend answered.
+    const provider = await this.transit.activeProvider(ctx.userId);
     let reservationParts: ReturnType<typeof buildTransitReservationParts>;
     try {
-      reservationParts = buildTransitReservationParts(from, to, cleaned);
+      reservationParts = buildTransitReservationParts(from, to, cleaned, provider);
     } catch (err) {
       return errorResult(err, 'Unable to resolve the transit journey timezones.');
     }

server/src/nest/transit/transit.service.ts

@@ -159,6 +159,11 @@ export class TransitService {
     @Inject(transitConfig.KEY) private readonly transitEnv: ConfigType<typeof transitConfig>,
   ) {}
 
+  /** The backend that answers this user's searches: Google where it is set up and keyed, Transitous otherwise. */
+  async activeProvider(userId = 0): Promise<TransitProvider> {
+    return (await this.google.isActive(userId)) ? 'google' : 'transitous';
+  }
+
   /**
    * Station/place search for the from/to pickers. `near` biases results.
    *
@@ -175,7 +180,7 @@ export class TransitService {
     const text = (query || '').trim();
     // Answered before either backend is consulted, so it reports the one that
     // WOULD have been asked rather than claiming nobody was.
-    const provider: TransitProvider = (await this.google.isActive(userId)) ? 'google' : 'transitous';
+    const provider = await this.activeProvider(userId);
     if (text.length < 2) return { results: [], provider };
     if (text.length > 200) {
       const e = new Error('Query too long') as Error & { status: number };
@@ -259,7 +264,7 @@ export class TransitService {
 
     // After validation on purpose: whichever backend answers, the caller is held
     // to the same coordinate/mode/transfer contract and gets the same 400s.
-    if (await this.google.isActive(userId)) {
+    if ((await this.activeProvider(userId)) === 'google') {
       return { ...(await this.google.plan(q, language, userId)), provider: 'google' };
     }
 

server/tests/unit/mcp/tools-transit.test.ts

@@ -201,6 +201,7 @@ describe('MCP transit tools', () => {
       expect(routes.itineraries[0].legs[0].from.name).toBe('Namba');
       expect(routes.itineraries[0].legs[1].to.name).toBe('Umeda');
       expect(routes.itineraries).toHaveLength(1);
+      expect(routes.provider).toBe('transitous');
       expect(planMock).toHaveBeenCalledWith(expect.objectContaining({ modes: 'SUBWAY' }), undefined, user.id);
 
       const invalidNear = await harness.client.callTool({
@@ -244,6 +245,27 @@ describe('MCP transit tools', () => {
     });
   });
 
+  it('records Google as the provider of a journey planned while Google answers searches (#2850)', async () => {
+    const { user } = createUser(testDb);
+    const trip = createTrip(testDb, user.id, { start_date: '2026-12-03', end_date: '2026-12-04' });
+    const day = await dayOf(trip.id, '2026-12-03');
+    const active = vi.spyOn(TransitService.prototype, 'activeProvider').mockResolvedValue('google');
+    try {
+      await withHarness(user.id, ['reservations:write'], async (harness) => {
+        const result = parseToolResult(
+          await harness.client.callTool({
+            name: 'create_transit_journey',
+            arguments: { tripId: trip.id, dayId: day.id, from, to, itinerary },
+          }),
+        ) as { reservation: { metadata: string } };
+        expect(JSON.parse(result.reservation.metadata).transit.provider).toBe('google');
+      });
+      expect(active).toHaveBeenCalledWith(user.id);
+    } finally {
+      active.mockRestore();
+    }
+  });
+
   it('rejects dateless, mismatched, and out-of-range journey dates', async () => {
     const { user } = createUser(testDb);
     const datelessTrip = createTrip(testDb, user.id);

server/tests/unit/nest/transit-itinerary.helpers.test.ts

@@ -311,7 +311,7 @@ describe('buildTransitReservationParts', () => {
       ],
     };
 
-    const { endpoints, metadata } = buildTransitReservationParts(namba, kyoto, itinerary);
+    const { endpoints, metadata } = buildTransitReservationParts(namba, kyoto, itinerary, 'transitous');
 
     expect(endpoints).toEqual([
       {
@@ -407,7 +407,7 @@ describe('buildTransitReservationParts', () => {
     const kyoto = { name: 'Kyoto', lat: 35.0116, lng: 135.7681 };
     const itinerary = twoLegs();
     itinerary.legs = [{ ...itinerary.legs[0], to: stop('Umeda', 34.702, 135.496, null) }, itinerary.legs[1]];
-    const { endpoints, metadata } = buildTransitReservationParts(namba, kyoto, itinerary);
+    const { endpoints, metadata } = buildTransitReservationParts(namba, kyoto, itinerary, 'transitous');
     expect(endpoints[1]).toEqual({
       role: 'stop',
       sequence: 1,
@@ -423,14 +423,18 @@ describe('buildTransitReservationParts', () => {
   });
 
   it('TRANSIT-ITIN-020: an unresolvable endpoint timezone throws with the coordinates in the message', () => {
-    expect(() => buildTransitReservationParts({ name: 'Nowhere', lat: NaN, lng: 135.501 }, umeda, singleLeg())).toThrow(
-      'Unable to resolve timezone for NaN,135.501.',
-    );
+    expect(() =>
+      buildTransitReservationParts({ name: 'Nowhere', lat: NaN, lng: 135.501 }, umeda, singleLeg(), 'transitous'),
+    ).toThrow('Unable to resolve timezone for NaN,135.501.');
   });
 
   it('TRANSIT-ITIN-021: an unconvertible itinerary time throws with the ISO string and timezone', () => {
-    expect(() => buildTransitReservationParts(namba, umeda, singleLeg({ startTime: 'not-a-date' }))).toThrow(
-      'Unable to convert not-a-date to local time in Asia/Tokyo.',
-    );
+    expect(() =>
+      buildTransitReservationParts(namba, umeda, singleLeg({ startTime: 'not-a-date' }), 'transitous'),
+    ).toThrow('Unable to convert not-a-date to local time in Asia/Tokyo.');
+  });
+
+  it('TRANSIT-ITIN-022: the journey records the backend its itinerary came from (#2850)', () => {
+    expect(buildTransitReservationParts(namba, umeda, singleLeg(), 'google').metadata.transit.provider).toBe('google');
   });
 });

wiki/MCP-Tools-and-Resources.md

@@ -133,8 +133,8 @@ Transit search is powered by Transitous and uses the existing `geo:read` and `re
 | Tool | Scope required | Description |
 |---|---|---|
 | `search_transit_stops` | `geo:read` | Search real public-transit stops and stations, optionally biased around coordinates. |
-| `search_transit_routes` | `geo:read` | Search scheduled routes between two coordinates with time, mode, and transfer filters. Also returns `dropped`, the number of provider itineraries that failed validation and are absent from the results. |
-| `create_transit_journey` | `reservations:write` | Save a selected route as a first-class automated transit journey on a trip day. |
+| `search_transit_routes` | `geo:read` | Search scheduled routes between two coordinates with time, mode, and transfer filters. Also returns `provider` (`transitous` or `google`, the backend that answered) and `dropped`, the number of provider itineraries that failed validation and are absent from the results. |
+| `create_transit_journey` | `reservations:write` | Save a selected route as a first-class automated transit journey on a trip day, recording the backend that plans routes for the caller as its provider. |
 
 ### Reservations