chore: move transitItineraryService into nest/transit as pure helpers

server/src/nest/README.md

@@ -29,7 +29,7 @@ mount to Nest and leaves the sibling trip routes (days, places, ...) on Express.
 - **DI-native services (legacy `src/services/*` deleted):** tags, categories,
   todo, packing, day-notes, trip-invite, assignments, share, settings, files,
   collab, vacay, reservations, day, permissions, audit, budget, trip, maps,
-  transit, place — see the migration recipe below.
+  transit, place, transit-itinerary — see the migration recipe below.
 
 ## Cross-cutting Foundation pieces
 
@@ -244,7 +244,8 @@ Transitous/MOTIS proxy became a dep-free `TransitService` (no
 frozen-at-import `TRANSIT_API_BASE` and lazy User-Agent memo staying
 module-scoped on purpose; the pure `deriveTransitStats` + mode whitelist +
 itinerary types moved to `transit.helpers.ts` (maps.helpers precedent) so the
-downstream legacy `transitItineraryService` needs no bridge; the whole 3-tool
+downstream legacy `transitItineraryService` needed no bridge (since relocated
+into the domain as `transit-itinerary.helpers.ts`); the whole 3-tool
 `mcp/tools/transit.ts` registrar moved to `transit.mcp.ts` — the two geo
 search tools on `access: { group: 'geo', mode: 'read' }` and
 `create_transit_journey` on `reservations:write`, with its days/reservations
@@ -278,9 +279,22 @@ empty-list short-circuit stays reachable, and retired three bespoke 400
 strings — 'Place name is required', 'ids must be an array of numbers' and
 'URL is required' — in favour of the pipe envelope, accepting that a
 malformed body now 400s ahead of the trip-access 404 (the todo/trips trade).
+transitItineraryService followed (the first pure-helpers relocation with no
+service fold at all — the 287-line module is 100% pure, so the recipe's SQL /
+bridge / DTO / plugin-host steps were all no-ops: the Zod itinerary schemas +
+endpoint/metadata builders moved byte-identical to
+`transit-itinerary.helpers.ts`, next to `transit.helpers.ts`; the schemas
+**must** stay module-level plain exports because `transit.mcp.ts` consumes
+them inside `@Tool({ inputSchema })` decorators, which evaluate at module load
+before any container exists; the sole consumer — the in-container
+`transit.mcp.ts` — was a one-import repoint, closing step 4 of the
+dependency-honest order; the legacy module had no direct suite, so a new
+21-case `TRANSIT-ITIN-*` characterization suite now pins all 12 superRefine
+error strings, the `??` time fallbacks, the coordinate tolerances and the
+reservation endpoint/metadata builder).
 Repeat these steps per
-service (next up: **transitItineraryService** —
-or the notifications fan-in — per the dependency-honest order in
+service (next up: **the notifications fan-in** —
+per the dependency-honest order in
 `migration-graph.md`). This is a
 **pure relocation** — byte-identical
 SQL, statuses, bodies, and error strings. The plugin RPC host is **no longer a

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

@@ -1,7 +1,16 @@
-import { haversineKm } from './distanceService';
-import type { EndpointInput } from '../nest/reservations/reservations.bridge';
-import { localParts, resolveTimeZone } from './timezoneService';
-import { deriveTransitStats, type TransitItinerary, type TransitLeg } from '../nest/transit/transit.helpers';
+/**
+ * Pure transit-itinerary helpers — the wire schemas for provider itineraries
+ * plus the endpoint/metadata builder for automated transit reservations.
+ * Moved 1:1 from the legacy services/transitItineraryService.ts (identical
+ * schemas, tolerances, error strings and output shapes). Kept as plain
+ * exports (the maps.helpers.ts precedent): the schemas are consumed inside
+ * transit.mcp.ts's @Tool inputSchema decorators, which evaluate at module
+ * load — before any DI container exists — so they must stay module-level.
+ */
+import { haversineKm } from '../../services/distanceService';
+import type { EndpointInput } from '../reservations/reservations.service';
+import { localParts, resolveTimeZone } from '../../services/timezoneService';
+import { deriveTransitStats, type TransitItinerary, type TransitLeg } from './transit.helpers';
 
 import { z } from 'zod';
 

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

@@ -1,9 +1,8 @@
 /**
- * Pure transit helpers shared by TransitService and plain-module code outside
- * the container (the legacy services/transitItineraryService imports
- * deriveTransitStats + the itinerary types). Kept as plain functions/consts
- * (the maps.helpers.ts / files.constants.ts precedent) so no bridge is needed —
- * helpers never block a migration.
+ * Pure transit helpers shared by TransitService and the itinerary
+ * validation/reservation builders in transit-itinerary.helpers.ts. Kept as
+ * plain functions/consts (the maps.helpers.ts / files.constants.ts
+ * precedent) — helpers never block a migration.
  */
 
 // Modes the client may request — a strict whitelist so the proxy can't be used

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

@@ -12,7 +12,7 @@ import {
   transitCoordinatesSchema,
   transitItinerarySchema,
   transitPlaceSchema,
-} from '../../services/transitItineraryService';
+} from './transit-itinerary.helpers';
 import { hasTripPermission, noAccess, permissionDenied, safeBroadcast } from '../../mcp/tools/_shared';
 import { RateLimitService } from '../auth/rate-limit.service';
 import { DatabaseService } from '../database/database.service';
@@ -54,8 +54,7 @@ function rateLimit(userId: number, bucket: string, max: number) {
  * scope group — there is no geo:write) and the `canWrite(scopes,
  * 'reservations')` early return on create_transit_journey. The
  * days/reservations bridge imports became injected services; the itinerary
- * schemas/helpers still come from the legacy transitItineraryService until
- * that domain migrates.
+ * schemas/helpers live in the colocated transit-itinerary.helpers.ts.
  */
 @McpController()
 export class TransitMcp {

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

@@ -126,7 +126,7 @@ function mapStop(p: MotisPlaceRaw | undefined, kind: 'departure' | 'arrival'): T
     // A missing coordinate becomes 0 (null island) rather than null on
     // purpose: TransitLegStop.lat/lng are non-nullable across the wire
     // contract (transitStopSchema, the client picker) — making them nullable
-    // would ripple through transitItineraryService's validation and drop
+    // would ripple through transit-itinerary.helpers' validation and drop
     // otherwise-usable itineraries. MOTIS places carry coordinates in
     // practice; endpoint stops are re-checked by transitCoordinatesMatch.
     lat: typeof p?.lat === 'number' ? p.lat : 0,