fix(journey): keep the photo picker's calendar inside the screen

The date picker of the external photo picker hung absolutely under its
trigger, inside a dialog that clips its content. The last week of a
six-week month fell below the dialog, and for the end date in the
right-hand column the calendar opened past the dialog's right edge, so
the last weekday and the next-month arrow could not be reached.

The calendar now opens in a portal, pinned to its trigger through
useAnchoredPosition: it flips above the trigger when below is too short,
scrolls when neither side holds it, and is kept inside the viewport
sideways.

Closes #2858

client/src/components/Journey/JourneyDetailPageDatePicker.test.tsx

@@ -1,4 +1,4 @@
-// FE-COMP-JOURNEYDATEPICKER-001 to FE-COMP-JOURNEYDATEPICKER-007
+// FE-COMP-JOURNEYDATEPICKER-001 to FE-COMP-JOURNEYDATEPICKER-008
 import React from 'react'
 import { describe, it, expect, vi } from 'vitest'
 import { render, screen } from '../../../tests/helpers/render'
@@ -119,3 +119,28 @@ describe('DatePicker week start (#2029)', () => {
     }
   })
 })
+
+describe('DatePicker inside a clipping dialog (#2858)', () => {
+  it('FE-COMP-JOURNEYDATEPICKER-008: the calendar floats over the page, stays inside the viewport and closes on a click away', async () => {
+    const user = userEvent.setup()
+    const { container } = render(
+      <div style={{ overflow: 'hidden' }}>
+        <DatePicker value="2026-03-15" onChange={vi.fn()} />
+      </div>,
+    )
+    const trigger = screen.getByText(/Mar 15, 2026/).closest('button') as HTMLButtonElement
+    // A trigger at the right edge, where the end date of a range sits.
+    trigger.getBoundingClientRect = () => ({ top: 100, bottom: 136, left: window.innerWidth - 120, right: window.innerWidth - 8, width: 112, height: 36, x: 0, y: 0, toJSON: () => ({}) })
+    await user.click(trigger)
+
+    const day31 = screen.getByRole('button', { name: '31' })
+    // Rendered outside the dialog that would clip it.
+    expect(container.contains(day31)).toBe(false)
+    const panel = day31.closest('.fixed') as HTMLElement
+    expect(panel.style.top).toBe('140px')
+    expect(parseFloat(panel.style.left)).toBe(window.innerWidth - 280 - 8)
+
+    await user.click(document.querySelector('[role="presentation"]') as HTMLElement)
+    expect(screen.queryByRole('button', { name: '31' })).toBeNull()
+  })
+})

client/src/components/Journey/JourneyDetailPageDatePicker.tsx

@@ -1,9 +1,11 @@
-import { useState } from 'react'
+import { useRef, useState } from 'react'
+import { createPortal } from 'react-dom'
 import { localIsoDate } from '../../utils/localDate'
 import { ArrowLeft, ChevronRight, Calendar } from 'lucide-react'
 import { useTranslation } from '../../i18n'
 import { useWeekStartDay } from '../../hooks/useWeekStartDay'
 import { leadingBlanks, weekdayLabels } from '../../utils/calendarWeek'
+import { useAnchoredPosition } from '../../hooks/useAnchoredPosition'
 
 /**
  * The header steps up a level on each click, days → months → years, and a
@@ -14,6 +16,9 @@ import { leadingBlanks, weekdayLabels } from '../../utils/calendarWeek'
  */
 type CalendarView = 'days' | 'months' | 'years'
 const YEAR_PAGE_SIZE = 12
+/** The calendar's width; `w-[280px]` below. */
+const PANEL_WIDTH = 280
+const VIEWPORT_PAD = 8
 
 export function DatePicker({ value, onChange, tripDates }: {
   value: string
@@ -23,6 +28,13 @@ export function DatePicker({ value, onChange, tripDates }: {
   const { t, locale } = useTranslation()
   const weekStart = useWeekStartDay()
   const [open, setOpen] = useState(false)
+  const triggerRef = useRef<HTMLButtonElement>(null)
+  // The calendar used to hang absolutely under its trigger, inside dialogs that clip
+  // their content: the photo picker cut off the last week and, for the end date in
+  // the right-hand column, the last weekday (#2858). It now floats over the page,
+  // pinned to the trigger, flipped above it when below is too short and kept inside
+  // the viewport sideways.
+  const anchored = useAnchoredPosition(triggerRef, open, { estimatedHeight: 340, matchWidth: false })
   const [view, setView] = useState<CalendarView>('days')
   const [yearPageStart, setYearPageStart] = useState(0)
   const [viewMonth, setViewMonth] = useState(() => {
@@ -107,6 +119,7 @@ export function DatePicker({ value, onChange, tripDates }: {
   return (
     <div className="relative">
       <button
+        ref={triggerRef}
         type="button"
         onClick={toggleOpen}
         className="w-full px-3 py-2 border border-zinc-200 dark:border-zinc-700 rounded-lg text-[13px] bg-white dark:bg-zinc-800 text-zinc-900 dark:text-white text-start flex items-center justify-between"
@@ -122,12 +135,20 @@ export function DatePicker({ value, onChange, tripDates }: {
         <Calendar size={13} className="text-zinc-400" />
       </button>
 
-      {open && (
+      {open && anchored && createPortal(
         <>
           {/* Click-away catcher — no semantics of its own; the trigger button
               above closes the popover again from the keyboard. */}
-          <div role="presentation" className="fixed inset-0 z-[10]" onClick={() => setOpen(false)} />
-          <div className="absolute top-full start-0 mt-1 z-[20] bg-white dark:bg-zinc-800 border border-zinc-200 dark:border-zinc-700 rounded-xl shadow-lg p-3 w-[280px]">
+          <div role="presentation" className="fixed inset-0 z-[var(--z-toast)]" onClick={() => setOpen(false)} />
+          <div
+            className="fixed z-[var(--z-toast)] overflow-y-auto bg-white dark:bg-zinc-800 border border-zinc-200 dark:border-zinc-700 rounded-xl shadow-lg p-3 w-[280px]"
+            style={{
+              top: anchored.top,
+              bottom: anchored.bottom,
+              left: Math.max(VIEWPORT_PAD, Math.min(anchored.left, window.innerWidth - PANEL_WIDTH - VIEWPORT_PAD)),
+              maxHeight: anchored.maxHeight,
+            }}
+          >
             {/* Header: arrows step the current view, the label climbs to the next one up */}
             <div className="flex items-center justify-between mb-2">
               <button type="button" onClick={handlePrev} aria-label={prevLabel} className={navButton}>
@@ -200,7 +221,7 @@ export function DatePicker({ value, onChange, tripDates }: {
                       >
                         {day}
                         {isTrip && !isSelected && (
-                          <span className="absolute bottom-1 left-1/2 -translate-x-1/2 w-1 h-1 rounded-full bg-indigo-500" />
+                          <span className="absolute bottom-1 inset-x-0 mx-auto w-1 h-1 rounded-full bg-indigo-500" />
                         )}
                       </button>
                     )
@@ -209,7 +230,8 @@ export function DatePicker({ value, onChange, tripDates }: {
               </>
             )}
           </div>
-        </>
+        </>,
+        document.body,
       )}
     </div>
   )

client/src/components/Journey/JourneyDetailPageProviderPicker.test.tsx

@@ -375,11 +375,12 @@ describe('ProviderPicker', () => {
     await user.click(screen.getByRole('button', { name: 'Search' }))
     expect(ranges).toHaveLength(0)
 
+    // The calendar opens in a portal, so its days are looked up on the page, not under the trigger.
     const [fromPicker, toPicker] = Array.from(baseElement.querySelectorAll('.flex-1 > .relative')) as HTMLElement[]
     await user.click(within(fromPicker).getByRole('button'))
-    await user.click(within(fromPicker).getByRole('button', { name: '3' }))
+    await user.click(screen.getByRole('button', { name: '3' }))
     await user.click(within(toPicker).getByRole('button'))
-    await user.click(within(toPicker).getByRole('button', { name: '9' }))
+    await user.click(screen.getByRole('button', { name: '9' }))
     await user.click(screen.getByRole('button', { name: 'Search' }))
 
     await waitFor(() => expect(ranges).toHaveLength(1))

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/db/json-columns.ts

@@ -375,6 +375,12 @@ const aiProviderStateSchema = z.discriminatedUnion('adapter', [
     adapter: z.literal('anthropic-messages'),
     blocks: z.array(z.record(z.string(), z.unknown())),
   }),
+  // Gemini's thought signature per tool call id, which its Chat Completions endpoint wants back with the call.
+  z.object({
+    adapter: z.literal('openai-chat'),
+    model: z.string(),
+    signatures: z.record(z.string(), z.string()),
+  }),
 ]);
 export type AiProviderState = z.infer<typeof aiProviderStateSchema>;
 

server/src/nest/ai-connections/providers/openai-chat.client.ts

@@ -26,16 +26,29 @@ import type { AiConnectionKind } from '@trek/shared';
 /** The end of an OpenAI-compatible stream. */
 const DONE = '[DONE]';
 
+/** The host of Gemini's OpenAI-compatible endpoint, which an admin may also enter as their own server. */
+const GEMINI_HOST = 'generativelanguage.googleapis.com';
+
+function isGeminiHost(baseUrl: string): boolean {
+  try {
+    return new URL(baseUrl).hostname === GEMINI_HOST;
+  } catch {
+    return false;
+  }
+}
+
 /**
  * The provider-neutral history as Chat Completions messages, the instructions
  * and the trip card first. A tool message takes no image, so the images of a
- * step's tool results follow its last result as one user message.
+ * step's tool results follow its last result as one user message. `model` is
+ * the one the request goes to: a thought signature goes back only to the model
+ * that signed it, since another one cannot read it.
  */
-export function toChatMessages(request: AiChatRequest): Record<string, unknown>[] {
+export function toChatMessages(request: AiChatRequest, model?: string): Record<string, unknown>[] {
   const system = [request.system, request.context].filter(Boolean).join('\n\n');
   const out: Record<string, unknown>[] = [{ role: 'system', content: system }];
   request.messages.forEach((message, index) => {
-    out.push(toChatMessage(message));
+    out.push(toChatMessage(message, model));
     const withImages = toolImagesEndingAt(request.messages, index);
     if (withImages.length === 0) return;
     const content = withImages.flatMap((tool) => [
@@ -51,12 +64,14 @@ function imagePart(image: AiImage): Record<string, unknown> {
   return { type: 'image_url', image_url: { url: imageDataUrl(image), detail: image.detail ?? 'high' } };
 }
 
-function toChatMessage(message: AiChatMessage): Record<string, unknown> {
+function toChatMessage(message: AiChatMessage, model: string | undefined): Record<string, unknown> {
   if (message.role === 'user') {
     if (!message.images?.length) return { role: 'user', content: message.text };
     return { role: 'user', content: [{ type: 'text', text: message.text }, ...message.images.map(imagePart)] };
   }
   if (message.role === 'tool') return { role: 'tool', tool_call_id: message.toolCallId, content: message.output };
+  const state = message.providerState;
+  const signatures = state?.adapter === 'openai-chat' && state.model === model ? state.signatures : {};
   return {
     role: 'assistant',
     content: message.text || null,
@@ -66,19 +81,32 @@ function toChatMessage(message: AiChatMessage): Record<string, unknown> {
             id: call.id,
             type: 'function',
             function: { name: call.name, arguments: JSON.stringify(call.args) },
+            ...(signatures[call.id] ? { extra_content: { google: { thought_signature: signatures[call.id] } } } : {}),
           })),
         }
       : {}),
   };
 }
 
+/** Gemini signs a tool call on its first piece; the call has to go back with it or the next request is refused. */
+function thoughtSignatureOf(piece: Record<string, unknown>): string {
+  return asText(asRecord(asRecord(piece.extra_content).google).thought_signature);
+}
+
+/** The id a call goes on with; a provider that names none gets one from the call's position. */
+function callId(index: number, id: string): string {
+  return id || `call_${index}`;
+}
+
 const FINISH_REASONS: Record<string, AiFinishReason> = { tool_calls: 'tool-calls', length: 'length' };
 
 /**
  * The OpenAI-compatible Chat Completions API, streamed: OpenAI itself, Gemini
  * (its `/v1beta/openai` endpoint), OpenRouter and an admin's own server. The
  * kind decides only what a request may carry: Gemini gets its narrower tool
- * schemas, OpenAI the prompt cache key, which the others do not know.
+ * schemas, also when an admin enters its endpoint as their own server, and
+ * OpenAI the prompt cache key, which the others do not know. Gemini's thought
+ * signatures come back as the turn's provider state.
  */
 export class OpenAiChatClient implements AiChatClient {
   /** OpenRouter searches the web for any model through its web plugin; the others have no search here. */
@@ -86,20 +114,25 @@ export class OpenAiChatClient implements AiChatClient {
     return this.kind === 'openrouter';
   }
 
+  /** The kind whose tool schemas the endpoint takes. */
+  private readonly schemaKind: AiConnectionKind;
+
   constructor(
     readonly kind: AiConnectionKind,
     readonly model: string,
     private readonly baseUrl: string,
     private readonly apiKey: string | null,
     private readonly fetcher: AiFetch,
-  ) {}
+  ) {
+    this.schemaKind = kind === 'custom' && isGeminiHost(baseUrl) ? 'gemini' : kind;
+  }
 
   async *stream(request: AiChatRequest, signal: AbortSignal): AsyncGenerator<AiChatEvent> {
     const body = {
       model: this.model,
       stream: true,
       stream_options: { include_usage: true },
-      messages: toChatMessages(request),
+      messages: toChatMessages(request, this.model),
       ...(request.tools.length > 0
         ? {
             tools: request.tools.map((tool) => ({
@@ -107,7 +140,7 @@ export class OpenAiChatClient implements AiChatClient {
               function: {
                 name: tool.name,
                 description: tool.description,
-                parameters: toProviderSchema(tool.parameters, this.kind),
+                parameters: toProviderSchema(tool.parameters, this.schemaKind),
               },
             })),
             tool_choice: 'auto',
@@ -153,10 +186,22 @@ export class OpenAiChatClient implements AiChatClient {
       cachedInputTokens: turn.cachedInputTokens,
       outputTokens: turn.outputTokens,
     };
+    const signatures = turn.signatures();
+    if (Object.keys(signatures).length > 0) {
+      yield { type: 'provider-state', state: { adapter: 'openai-chat', model: this.model, signatures } };
+    }
     yield { type: 'finish', reason: turn.finishReason() };
   }
 }
 
+/** A tool call while it streams in: its id, name and arguments so far, and Gemini's signature. */
+interface PendingCall {
+  id: string;
+  name: string;
+  args: string;
+  signature: string;
+}
+
 /**
  * What one streamed Chat Completions turn has said so far. A tool call
  * arrives in pieces keyed by its index (its id and name in the first, the
@@ -168,7 +213,7 @@ class ChatTurn {
   outputTokens = 0;
   reason: string | null = null;
   done = false;
-  private readonly pending = new Map<number, { id: string; name: string; args: string }>();
+  private readonly pending = new Map<number, PendingCall>();
   private readonly cited = new Set<string>();
   private fresh: AiSource[] = [];
 
@@ -199,10 +244,11 @@ class ChatTurn {
       const piece = asRecord(raw);
       const index = typeof piece.index === 'number' ? piece.index : position;
       const fn = asRecord(piece.function);
-      const call = this.pending.get(index) ?? { id: '', name: '', args: '' };
+      const call = this.pending.get(index) ?? { id: '', name: '', args: '', signature: '' };
       call.id ||= asText(piece.id);
       call.name ||= asText(fn.name);
       call.args += asText(fn.arguments);
+      call.signature ||= thoughtSignatureOf(piece);
       this.pending.set(index, call);
     });
     return asText(delta.content);
@@ -216,10 +262,24 @@ class ChatTurn {
   }
 
   calls(): AiToolCall[] {
-    return [...this.pending.entries()]
-      .sort(([a], [b]) => a - b)
-      .filter(([, call]) => call.name)
-      .map(([index, call]) => ({ id: call.id || `call_${index}`, name: call.name, args: parseToolArgs(call.args) }));
+    return this.named().map(([index, call]) => ({
+      id: callId(index, call.id),
+      name: call.name,
+      args: parseToolArgs(call.args),
+    }));
+  }
+
+  /** The thought signature of each signed call, by the id the call goes back with. */
+  signatures(): Record<string, string> {
+    return Object.fromEntries(
+      this.named()
+        .filter(([, call]) => call.signature)
+        .map(([index, call]) => [callId(index, call.id), call.signature]),
+    );
+  }
+
+  private named(): [number, PendingCall][] {
+    return [...this.pending.entries()].sort(([a], [b]) => a - b).filter(([, call]) => call.name);
   }
 
   finishReason(): AiFinishReason {

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/ai-connections/provider-adapters.test.ts

@@ -529,6 +529,125 @@ describe('OpenAiChatClient', () => {
       await failure(client(streamResponse([{ choices: [{ delta: { content: 'half' } }] }])).stream(REQUEST, signal())),
     ).toMatchObject({ providerCode: 'stream_cut' });
   });
+
+  // Gemini 3 signs the first call of a step on its first piece, the way its Chat Completions endpoint streams it.
+  const SIGNED = [
+    {
+      choices: [
+        {
+          delta: {
+            tool_calls: [
+              {
+                index: 0,
+                id: 'function-call-1',
+                type: 'function',
+                function: { name: 'create_place', arguments: '{"name":"Nijo"}' },
+                extra_content: { google: { thought_signature: 'sig-A' } },
+              },
+            ],
+          },
+        },
+      ],
+    },
+    {
+      choices: [
+        {
+          delta: {
+            tool_calls: [{ index: 1, function: { name: 'list_places', arguments: '{}' } }],
+          },
+          finish_reason: 'tool_calls',
+        },
+      ],
+    },
+    '[DONE]',
+  ];
+
+  it('OACH-006: a signed call comes back as the provider state, keyed by the id it goes on with', async () => {
+    const events = await run(
+      new OpenAiChatClient(
+        'gemini',
+        'gemini-3-flash',
+        'https://g',
+        'k',
+        fetchAnswering(streamResponse(SIGNED)).fetcher,
+      ).stream(REQUEST, signal()),
+    );
+    expect(events.filter((event) => event.type === 'tool-call')).toEqual([
+      { type: 'tool-call', call: { id: 'function-call-1', name: 'create_place', args: { name: 'Nijo' } } },
+      { type: 'tool-call', call: { id: 'call_1', name: 'list_places', args: {} } },
+    ]);
+    expect(events.slice(-2)).toEqual([
+      {
+        type: 'provider-state',
+        state: { adapter: 'openai-chat', model: 'gemini-3-flash', signatures: { 'function-call-1': 'sig-A' } },
+      },
+      { type: 'finish', reason: 'tool-calls' },
+    ]);
+
+    // An unsigned turn keeps no state: nothing is stored for a provider that signs nothing.
+    const plain = await run(
+      new OpenAiChatClient('openai', 'm', 'https://x', 'k', fetchAnswering(streamResponse(STREAM)).fetcher).stream(
+        REQUEST,
+        signal(),
+      ),
+    );
+    expect(plain.some((event) => event.type === 'provider-state')).toBe(false);
+  });
+
+  it('OACH-007: the signature goes back with its call to the model that signed it, and to no other', async () => {
+    const signed: AiChatRequest = {
+      ...REQUEST,
+      messages: [
+        { role: 'user', text: 'Add Nijo' },
+        {
+          role: 'assistant',
+          text: '',
+          toolCalls: [
+            { id: 'function-call-1', name: 'create_place', args: { name: 'Nijo' } },
+            { id: 'call_1', name: 'list_places', args: {} },
+          ],
+          providerState: {
+            adapter: 'openai-chat',
+            model: 'gemini-3-flash',
+            signatures: { 'function-call-1': 'sig-A' },
+          },
+        },
+        { role: 'tool', toolCallId: 'function-call-1', name: 'create_place', output: '{"id":7}' },
+        { role: 'tool', toolCallId: 'call_1', name: 'list_places', output: '[]' },
+      ],
+    };
+    const http = fetchAnswering(streamResponse(['[DONE]']));
+    await run(
+      new OpenAiChatClient('gemini', 'gemini-3-flash', 'https://g', 'k', http.fetcher).stream(signed, signal()),
+    );
+    expect(dig(http.body(), 'messages', 2, 'tool_calls')).toEqual([
+      {
+        id: 'function-call-1',
+        type: 'function',
+        function: { name: 'create_place', arguments: '{"name":"Nijo"}' },
+        extra_content: { google: { thought_signature: 'sig-A' } },
+      },
+      { id: 'call_1', type: 'function', function: { name: 'list_places', arguments: '{}' } },
+    ]);
+
+    // A thread that moved on to another model sends the calls plain: no other model reads the signature.
+    for (const messages of [toChatMessages(signed, 'gpt-5-mini'), toChatMessages(signed)]) {
+      expect(JSON.stringify(messages)).not.toContain('extra_content');
+    }
+  });
+
+  it('OACH-008: an own server on Gemini’s endpoint gets Gemini’s narrower schemas, any other the full ones', async () => {
+    const parameters = async (baseUrl: string) => {
+      const http = fetchAnswering(streamResponse(['[DONE]']));
+      await run(new OpenAiChatClient('custom', 'm', baseUrl, 'k', http.fetcher).stream(REQUEST, signal()));
+      return dig(http.body(), 'tools', 0, 'function', 'parameters');
+    };
+    expect(await parameters('https://generativelanguage.googleapis.com/v1beta/openai')).toEqual(
+      toProviderSchema(TOOL.parameters, 'gemini'),
+    );
+    expect(await parameters('http://ollama:11434/v1')).toEqual(toProviderSchema(TOOL.parameters, 'custom'));
+    expect(await parameters('not a url')).toEqual(toProviderSchema(TOOL.parameters, 'custom'));
+  });
 });
 
 describe('OpenAiResponsesClient', () => {

server/tests/unit/nest/assistant/assistant-history.test.ts

@@ -8,6 +8,7 @@ import type { AssistantMessageRow } from '../../../../src/db/repositories/Assist
 import type { AssistantToolCallRow } from '../../../../src/db/repositories/AssistantToolCalls.repository';
 import type { AiChatMessage } from '../../../../src/nest/ai-connections/ai-chat-client.interface';
 import { toAnthropicMessages } from '../../../../src/nest/ai-connections/providers/anthropic-messages.client';
+import { toChatMessages } from '../../../../src/nest/ai-connections/providers/openai-chat.client';
 import { toResponsesInput } from '../../../../src/nest/ai-connections/providers/openai-responses.client';
 import {
   messageIdOf,
@@ -573,6 +574,23 @@ describe('toChatHistory: calls the model made of the server tools (#2845)', () =
     expect(messages.flatMap((message) => message.content).some((block) => block.text === '')).toBe(false);
   });
 
+  it('ASTHIS-018: Gemini gets every stored call back with its thought signature, an applied change included', () => {
+    const state = (id: string, signature: string) => ({
+      adapter: 'openai-chat',
+      model: 'gemini-3-flash',
+      signatures: { [id]: signature },
+    });
+    type SentCall = { id: string; extra_content?: { google: { thought_signature: string } } };
+    const history = appliedAfterANote(state('call_note', 'sig-note'), state('call_move', 'sig-move'));
+    const sent = toChatMessages({ system: '', messages: history, tools: [] }, 'gemini-3-flash')
+      .flatMap((message) => (message.tool_calls ?? []) as SentCall[])
+      .map((call) => [call.id, call.extra_content?.google.thought_signature]);
+    expect(sent).toEqual([
+      ['call_note', 'sig-note'],
+      ['call_move', 'sig-move'],
+    ]);
+  });
+
   it('ASTHIS-017: a step that only kept a note is the model call it was, answered with what was kept', () => {
     const history = toChatHistory(
       [

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