feat: Add combined track functionality with repository and service layers

- Introduced CombinedTrackModel, CombinedTrackCreate, and CombinedTrackRepository for managing combined tracks.
- Implemented logic to create combined tracks based on existing tracks between two stations.
- Added methods to check for existing combined tracks and retrieve constituent track IDs.
- Enhanced TrackModel and TrackRepository to support OSM ID and track updates.
- Created migration scripts for adding combined tracks table and OSM ID to tracks.
- Updated services and API endpoints to handle combined track operations.
- Added tests for combined track creation, repository methods, and API interactions.

TODO.md

@@ -1,80 +0,0 @@
-# Development TODO Plan
-
-## Phase 1 – Project Foundations
-
-- [x] Initialize Git hooks, linting, and formatting tooling (ESLint, Prettier, isort, black).
-- [x] Configure `pyproject.toml` or equivalent for backend dependency management.
-- [x] Scaffold FastAPI application entrypoint with health-check endpoint.
-- [x] Bootstrap React app with Vite/CRA, including routing skeleton and global state provider.
-- [x] Define shared TypeScript/Python models for core domain entities (tracks, stations, trains).
-- [x] Set up CI workflow for linting and test automation (GitHub Actions).
-
-## Phase 2 – Core Features
-
-- [x] Implement authentication flow (backend JWT, frontend login/register forms).
-- [x] Build map visualization integrating Leaflet with OSM tiles.
-- [x] Define geographic bounding boxes and filtering rules for importing real-world stations from OpenStreetMap.
-- [x] Implement an import script/CLI that pulls OSM station data and normalizes it to the PostGIS schema.
-- [x] Expose backend CRUD endpoints for stations (create, update, archive) with validation and geometry handling.
-- [x] Build React map tooling for selecting a station.
-- [x] Enhance map UI to support selecting two stations and previewing the rail corridor between them.
-- [x] Define track selection criteria and tagging rules for harvesting OSM rail segments within target regions.
-- [x] Extend the importer to load track geometries and associate them with existing stations.
-- [ ] Implement backend track-management APIs with length/speed validation and topology checks.
-- [ ] Implement track path mapping along existing OSM rail segments between chosen stations.
-- [ ] Design train connection manager requirements (link trains to operating tracks, manage consist data).
-- [ ] Implement backend services and APIs to attach trains to routes and update assignments.
-- [ ] Add UI flows for managing train connections, including visual feedback on the map.
-- [ ] Establish train scheduling service with validation rules, conflict detection, and persistence APIs.
-- [ ] Provide frontend scheduling tools (timeline or table view) for creating and editing train timetables.
-- [ ] Develop frontend dashboards for resources, schedules, and achievements.
-- [ ] Add real-time simulation updates (WebSocket layer, frontend subscription hooks).
-
-## Phase 3 – Data & Persistence
-
-- [x] Design PostgreSQL/PostGIS schema and migrations (Alembic or similar).
-- [x] Implement data access layer with SQLAlchemy and repository abstractions.
-- [ ] Decide on canonical fixture scope (demo geography, sample trains) and document expected dataset size.
-- [ ] Author fixture generation scripts that export JSON/GeoJSON compatible with the repository layer.
-- [x] Create ingestion utilities to load fixtures into local and CI databases.
-- [ ] Provision a Redis instance/container for local development.
-- [ ] Add caching abstractions in backend services (e.g., network snapshot, map layers).
-- [ ] Implement cache invalidation hooks tied to repository mutations.
-
-## Phase 4 – Testing & Quality
-
-- [x] Write unit tests for backend services and models.
-- [ ] Configure Jest/RTL testing utilities and shared mocks for Leaflet and network APIs.
-- [ ] Write component tests for map controls, station builder UI, and dashboards.
-- [ ] Add integration tests for custom hooks (network snapshot, scheduling forms).
-- [x] Stand up Playwright/Cypress project structure with authentication helpers.
-- [x] Script login end-to-end flow (Playwright).
-- [ ] Script station creation end-to-end flow.
-- [ ] Script track placement end-to-end flow.
-- [ ] Script scheduling end-to-end flow.
-- [ ] Define load/performance targets (requests per second, simulation latency) and tooling.
-- [ ] Implement performance test harness covering scheduling and real-time updates.
-
-## Phase 5 – Deployment & Ops
-
-- [x] Create Dockerfile for frontend.
-- [x] Create Dockerfile for backend.
-- [x] Create docker-compose for local development with Postgres/Redis dependencies.
-- [ ] Add task runner commands to orchestrate container workflows.
-- [ ] Set up CI/CD pipeline for automated builds, tests, and container publishing.
-- [ ] Provision infrastructure scripts (Terraform/Ansible) targeting initial cloud environment.
-- [ ] Define environment configuration strategy (secrets management, config maps).
-- [ ] Configure observability stack (logging, metrics, tracing).
-- [ ] Integrate tracing/logging exporters into backend services.
-- [ ] Document deployment pipeline and release process.
-
-## Phase 6 – Polish & Expansion
-
-- [ ] Add leaderboards and achievements logic with UI integration.
-- [ ] Design data model changes required for achievements and ranking.
-- [ ] Implement accessibility audit fixes (WCAG compliance).
-- [ ] Conduct accessibility audit (contrast, keyboard navigation, screen reader paths).
-- [ ] Optimize asset loading and introduce lazy loading strategies.
-- [ ] Establish performance budgets for bundle size and render times.
-- [ ] Evaluate multiplayer/coop roadmap and spike POCs where feasible.
-- [ ] Prototype networking approach (WebRTC/WebSocket) for cooperative sessions.

backend/Dockerfile

@@ -25,7 +25,7 @@ EXPOSE 8000
 
 # Initialize database with demo data if INIT_DEMO_DB is set
 CMD ["sh", "-c", "\
-    export PYTHONPATH=/app && \
+    export PYTHONPATH=/app/backend && \
     echo 'Waiting for database...' && \
     while ! pg_isready -h db -p 5432 -U railgame >/dev/null 2>&1; do sleep 1; done && \
     echo 'Database is ready!' && \

backend/alembic.ini

@@ -1,6 +1,6 @@
 [alembic]
 script_location = migrations
-sqlalchemy.url = postgresql+psycopg://railgame:railgame@localhost:5432/railgame
+sqlalchemy.url = postgresql+psycopg://railgame:railgame@localhost:5432/railgame_dev
 
 [loggers]
 keys = root,sqlalchemy,alembic

backend/app/api/__init__.py

@@ -4,9 +4,11 @@ from backend.app.api.auth import router as auth_router
 from backend.app.api.health import router as health_router
 from backend.app.api.network import router as network_router
 from backend.app.api.stations import router as stations_router
+from backend.app.api.tracks import router as tracks_router
 
 router = APIRouter()
 router.include_router(health_router, tags=["health"])
 router.include_router(auth_router)
 router.include_router(network_router)
 router.include_router(stations_router)
+router.include_router(tracks_router)

backend/app/api/tracks.py

@@ -0,0 +1,153 @@
+from __future__ import annotations
+
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+
+from backend.app.api.deps import get_current_user, get_db
+from backend.app.models import (
+    CombinedTrackModel,
+    TrackCreate,
+    TrackUpdate,
+    TrackModel,
+    UserPublic,
+)
+from backend.app.services.combined_tracks import (
+    create_combined_track,
+    get_combined_track,
+    list_combined_tracks,
+)
+from backend.app.services.tracks import (
+    create_track,
+    delete_track,
+    regenerate_combined_tracks,
+    update_track,
+    get_track,
+    list_tracks,
+)
+
+router = APIRouter(prefix="/tracks", tags=["tracks"])
+
+
+@router.get("", response_model=list[TrackModel])
+def read_combined_tracks(
+    _: UserPublic = Depends(get_current_user),
+    db: Session = Depends(get_db),
+) -> list[TrackModel]:
+    """Return all base tracks."""
+    return list_tracks(db)
+
+
+@router.get("/combined", response_model=list[CombinedTrackModel])
+def read_combined_tracks_combined(
+    _: UserPublic = Depends(get_current_user),
+    db: Session = Depends(get_db),
+) -> list[CombinedTrackModel]:
+    return list_combined_tracks(db)
+
+
+@router.get("/{track_id}", response_model=TrackModel)
+def read_track(
+    track_id: str,
+    _: UserPublic = Depends(get_current_user),
+    db: Session = Depends(get_db),
+) -> TrackModel:
+    track = get_track(db, track_id)
+    if track is None:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"Track {track_id} not found",
+        )
+    return track
+
+
+@router.get("/combined/{combined_track_id}", response_model=CombinedTrackModel)
+def read_combined_track(
+    combined_track_id: str,
+    _: UserPublic = Depends(get_current_user),
+    db: Session = Depends(get_db),
+) -> CombinedTrackModel:
+    combined_track = get_combined_track(db, combined_track_id)
+    if combined_track is None:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"Combined track {combined_track_id} not found",
+        )
+    return combined_track
+
+
+@router.post("", response_model=TrackModel, status_code=status.HTTP_201_CREATED)
+def create_track_endpoint(
+    payload: TrackCreate,
+    regenerate: bool = False,
+    _: UserPublic = Depends(get_current_user),
+    db: Session = Depends(get_db),
+) -> TrackModel:
+    try:
+        track = create_track(db, payload)
+    except ValueError as exc:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST, detail=str(exc)
+        ) from exc
+
+    if regenerate:
+        regenerate_combined_tracks(
+            db, [track.start_station_id, track.end_station_id])
+
+    return track
+
+
+@router.post(
+    "/combined",
+    response_model=CombinedTrackModel,
+    status_code=status.HTTP_201_CREATED,
+    summary="Create a combined track between two stations using pathfinding",
+)
+def create_combined_track_endpoint(
+    start_station_id: str,
+    end_station_id: str,
+    _: UserPublic = Depends(get_current_user),
+    db: Session = Depends(get_db),
+) -> CombinedTrackModel:
+    combined_track = create_combined_track(
+        db, start_station_id, end_station_id)
+    if combined_track is None:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="Could not create combined track: no path exists between stations or track already exists",
+        )
+    return combined_track
+
+
+@router.put("/{track_id}", response_model=TrackModel)
+def update_track_endpoint(
+    track_id: str,
+    payload: TrackUpdate,
+    regenerate: bool = False,
+    _: UserPublic = Depends(get_current_user),
+    db: Session = Depends(get_db),
+) -> TrackModel:
+    track = update_track(db, track_id, payload)
+    if track is None:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"Track {track_id} not found",
+        )
+    if regenerate:
+        regenerate_combined_tracks(
+            db, [track.start_station_id, track.end_station_id])
+    return track
+
+
+@router.delete("/{track_id}", status_code=status.HTTP_204_NO_CONTENT)
+def delete_track_endpoint(
+    track_id: str,
+    regenerate: bool = False,
+    _: UserPublic = Depends(get_current_user),
+    db: Session = Depends(get_db),
+) -> None:
+    deleted = delete_track(db, track_id, regenerate=regenerate)
+    if not deleted:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"Track {track_id} not found",
+        )

backend/app/db/models.py

@@ -41,11 +41,14 @@ class User(Base, TimestampMixin):
     id: Mapped[uuid.UUID] = mapped_column(
         UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
     )
-    username: Mapped[str] = mapped_column(String(64), unique=True, nullable=False)
+    username: Mapped[str] = mapped_column(
-    email: Mapped[str | None] = mapped_column(String(255), unique=True, nullable=True)
+        String(64), unique=True, nullable=False)
+    email: Mapped[str | None] = mapped_column(
+        String(255), unique=True, nullable=True)
     full_name: Mapped[str | None] = mapped_column(String(128), nullable=True)
     password_hash: Mapped[str] = mapped_column(String(256), nullable=False)
-    role: Mapped[str] = mapped_column(String(32), nullable=False, default="player")
+    role: Mapped[str] = mapped_column(
+        String(32), nullable=False, default="player")
     preferences: Mapped[str | None] = mapped_column(Text, nullable=True)
 
 
@@ -62,12 +65,50 @@ class Station(Base, TimestampMixin):
         Geometry(geometry_type="POINT", srid=4326), nullable=False
     )
     elevation_m: Mapped[float | None] = mapped_column(Float, nullable=True)
-    is_active: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True)
+    is_active: Mapped[bool] = mapped_column(
+        Boolean, nullable=False, default=True)
 
 
 class Track(Base, TimestampMixin):
     __tablename__ = "tracks"
 
+    id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    osm_id: Mapped[str | None] = mapped_column(String(32), nullable=True)
+    name: Mapped[str | None] = mapped_column(String(128), nullable=True)
+    start_station_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("stations.id", ondelete="RESTRICT"),
+        nullable=False,
+    )
+    end_station_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True),
+        ForeignKey("stations.id", ondelete="RESTRICT"),
+        nullable=False,
+    )
+    length_meters: Mapped[float | None] = mapped_column(
+        Numeric(10, 2), nullable=True)
+    max_speed_kph: Mapped[int | None] = mapped_column(Integer, nullable=True)
+    is_bidirectional: Mapped[bool] = mapped_column(
+        Boolean, nullable=False, default=True
+    )
+    status: Mapped[str] = mapped_column(
+        String(32), nullable=False, default="planned")
+    track_geometry: Mapped[str] = mapped_column(
+        Geometry(geometry_type="LINESTRING", srid=4326), nullable=False
+    )
+
+    __table_args__ = (
+        UniqueConstraint(
+            "start_station_id", "end_station_id", name="uq_tracks_station_pair"
+        ),
+    )
+
+
+class CombinedTrack(Base, TimestampMixin):
+    __tablename__ = "combined_tracks"
+
     id: Mapped[uuid.UUID] = mapped_column(
         UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
     )
@@ -82,19 +123,25 @@ class Track(Base, TimestampMixin):
         ForeignKey("stations.id", ondelete="RESTRICT"),
         nullable=False,
     )
-    length_meters: Mapped[float | None] = mapped_column(Numeric(10, 2), nullable=True)
+    length_meters: Mapped[float | None] = mapped_column(
+        Numeric(10, 2), nullable=True)
     max_speed_kph: Mapped[int | None] = mapped_column(Integer, nullable=True)
     is_bidirectional: Mapped[bool] = mapped_column(
         Boolean, nullable=False, default=True
     )
-    status: Mapped[str] = mapped_column(String(32), nullable=False, default="planned")
+    status: Mapped[str] = mapped_column(
-    track_geometry: Mapped[str] = mapped_column(
+        String(32), nullable=False, default="planned")
+    combined_geometry: Mapped[str] = mapped_column(
         Geometry(geometry_type="LINESTRING", srid=4326), nullable=False
     )
+    # JSON array of constituent track IDs
+    constituent_track_ids: Mapped[str] = mapped_column(
+        Text, nullable=False
+    )
 
     __table_args__ = (
         UniqueConstraint(
-            "start_station_id", "end_station_id", name="uq_tracks_station_pair"
+            "start_station_id", "end_station_id", name="uq_combined_tracks_station_pair"
         ),
     )
 
@@ -105,7 +152,8 @@ class Train(Base, TimestampMixin):
     id: Mapped[uuid.UUID] = mapped_column(
         UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
     )
-    designation: Mapped[str] = mapped_column(String(64), nullable=False, unique=True)
+    designation: Mapped[str] = mapped_column(
+        String(64), nullable=False, unique=True)
     operator_id: Mapped[uuid.UUID | None] = mapped_column(
         UUID(as_uuid=True), ForeignKey("users.id", ondelete="SET NULL")
     )

backend/app/models/__init__.py

@@ -8,11 +8,14 @@ from .auth import (
     UserPublic,
 )
 from .base import (
+    CombinedTrackCreate,
+    CombinedTrackModel,
     StationCreate,
     StationModel,
     StationUpdate,
     TrackCreate,
     TrackModel,
+    TrackUpdate,
     TrainCreate,
     TrainModel,
     TrainScheduleCreate,
@@ -33,9 +36,12 @@ __all__ = [
     "StationUpdate",
     "TrackCreate",
     "TrackModel",
+    "TrackUpdate",
     "TrainScheduleCreate",
     "TrainCreate",
     "TrainModel",
     "UserCreate",
     "to_camel",
+    "CombinedTrackCreate",
+    "CombinedTrackModel",
 ]

backend/app/models/base.py

@@ -51,13 +51,24 @@ class StationModel(IdentifiedModel[str]):
 class TrackModel(IdentifiedModel[str]):
     start_station_id: str
     end_station_id: str
-    length_meters: float
+    length_meters: float | None = None
-    max_speed_kph: float
+    max_speed_kph: float | None = None
     status: str | None = None
     is_bidirectional: bool = True
     coordinates: list[tuple[float, float]] = Field(default_factory=list)
 
 
+class CombinedTrackModel(IdentifiedModel[str]):
+    start_station_id: str
+    end_station_id: str
+    length_meters: float | None = None
+    max_speed_kph: int | None = None
+    status: str | None = None
+    is_bidirectional: bool = True
+    coordinates: list[tuple[float, float]] = Field(default_factory=list)
+    constituent_track_ids: list[str] = Field(default_factory=list)
+
+
 class TrainModel(IdentifiedModel[str]):
     designation: str
     capacity: int
@@ -89,6 +100,31 @@ class TrackCreate(CamelModel):
     start_station_id: str
     end_station_id: str
     coordinates: Sequence[tuple[float, float]]
+    osm_id: str | None = None
+    name: str | None = None
+    length_meters: float | None = None
+    max_speed_kph: int | None = None
+    is_bidirectional: bool = True
+    status: str = "planned"
+
+
+class TrackUpdate(CamelModel):
+    start_station_id: str | None = None
+    end_station_id: str | None = None
+    coordinates: Sequence[tuple[float, float]] | None = None
+    osm_id: str | None = None
+    name: str | None = None
+    length_meters: float | None = None
+    max_speed_kph: int | None = None
+    is_bidirectional: bool | None = None
+    status: str | None = None
+
+
+class CombinedTrackCreate(CamelModel):
+    start_station_id: str
+    end_station_id: str
+    coordinates: Sequence[tuple[float, float]]
+    constituent_track_ids: list[str]
     name: str | None = None
     length_meters: float | None = None
     max_speed_kph: int | None = None

backend/app/repositories/__init__.py

@@ -2,6 +2,7 @@
 
 from backend.app.repositories.stations import StationRepository
 from backend.app.repositories.tracks import TrackRepository
+from backend.app.repositories.combined_tracks import CombinedTrackRepository
 from backend.app.repositories.train_schedules import TrainScheduleRepository
 from backend.app.repositories.trains import TrainRepository
 from backend.app.repositories.users import UserRepository
@@ -10,6 +11,7 @@ __all__ = [
     "StationRepository",
     "TrainScheduleRepository",
     "TrackRepository",
+    "CombinedTrackRepository",
     "TrainRepository",
     "UserRepository",
 ]

backend/app/repositories/combined_tracks.py

@@ -0,0 +1,73 @@
+from __future__ import annotations
+
+import json
+from uuid import UUID
+
+import sqlalchemy as sa
+from geoalchemy2.elements import WKTElement
+from sqlalchemy.orm import Session
+
+from backend.app.db.models import CombinedTrack
+from backend.app.models import CombinedTrackCreate
+from backend.app.repositories.base import BaseRepository
+
+
+class CombinedTrackRepository(BaseRepository[CombinedTrack]):
+    model = CombinedTrack
+
+    def __init__(self, session: Session) -> None:
+        super().__init__(session)
+
+    def list_all(self) -> list[CombinedTrack]:
+        statement = sa.select(self.model)
+        return list(self.session.scalars(statement))
+
+    def exists_between_stations(self, start_station_id: str, end_station_id: str) -> bool:
+        """Check if a combined track already exists between two stations."""
+        statement = sa.select(sa.exists().where(
+            sa.and_(
+                self.model.start_station_id == start_station_id,
+                self.model.end_station_id == end_station_id
+            )
+        ))
+        return bool(self.session.scalar(statement))
+
+    def get_constituent_track_ids(self, combined_track: CombinedTrack) -> list[str]:
+        """Extract constituent track IDs from a combined track."""
+        try:
+            return json.loads(combined_track.constituent_track_ids)
+        except (json.JSONDecodeError, TypeError):
+            return []
+
+    @staticmethod
+    def _ensure_uuid(value: UUID | str) -> UUID:
+        if isinstance(value, UUID):
+            return value
+        return UUID(str(value))
+
+    @staticmethod
+    def _line_string(coordinates: list[tuple[float, float]]) -> WKTElement:
+        if len(coordinates) < 2:
+            raise ValueError(
+                "Combined track geometry requires at least two coordinate pairs")
+        parts = [f"{lon} {lat}" for lat, lon in coordinates]
+        return WKTElement(f"LINESTRING({', '.join(parts)})", srid=4326)
+
+    def create(self, data: CombinedTrackCreate) -> CombinedTrack:
+        coordinates = list(data.coordinates)
+        geometry = self._line_string(coordinates)
+        constituent_track_ids_json = json.dumps(data.constituent_track_ids)
+        
+        combined_track = CombinedTrack(
+            name=data.name,
+            start_station_id=self._ensure_uuid(data.start_station_id),
+            end_station_id=self._ensure_uuid(data.end_station_id),
+            length_meters=data.length_meters,
+            max_speed_kph=data.max_speed_kph,
+            is_bidirectional=data.is_bidirectional,
+            status=data.status,
+            combined_geometry=geometry,
+            constituent_track_ids=constituent_track_ids_json,
+        )
+        self.session.add(combined_track)
+        return combined_track

backend/app/repositories/tracks.py

@@ -7,7 +7,7 @@ from geoalchemy2.elements import WKTElement
 from sqlalchemy.orm import Session
 
 from backend.app.db.models import Track
-from backend.app.models import TrackCreate
+from backend.app.models import TrackCreate, TrackUpdate
 from backend.app.repositories.base import BaseRepository
 
 
@@ -21,6 +21,102 @@ class TrackRepository(BaseRepository[Track]):
         statement = sa.select(self.model)
         return list(self.session.scalars(statement))
 
+    def exists_by_osm_id(self, osm_id: str) -> bool:
+        statement = sa.select(sa.exists().where(self.model.osm_id == osm_id))
+        return bool(self.session.scalar(statement))
+
+    def find_path_between_stations(self, start_station_id: str, end_station_id: str) -> list[Track] | None:
+        """Find the shortest path between two stations using existing tracks.
+
+        Returns a list of tracks that form the path, or None if no path exists.
+        """
+        # Build adjacency list: station -> list of (neighbor_station, track)
+        adjacency = self._build_track_graph()
+
+        if start_station_id not in adjacency or end_station_id not in adjacency:
+            return None
+
+        # BFS to find shortest path
+        from collections import deque
+
+        # (current_station, path_so_far)
+        queue = deque([(start_station_id, [])])
+        visited = set([start_station_id])
+
+        while queue:
+            current_station, path = queue.popleft()
+
+            if current_station == end_station_id:
+                return path
+
+            for neighbor, track in adjacency[current_station]:
+                if neighbor not in visited:
+                    visited.add(neighbor)
+                    queue.append((neighbor, path + [track]))
+
+        return None  # No path found
+
+    def _build_track_graph(self) -> dict[str, list[tuple[str, Track]]]:
+        """Build a graph representation of tracks: station -> [(neighbor_station, track), ...]"""
+        tracks = self.list_all()
+        graph = {}
+
+        for track in tracks:
+            start_id = str(track.start_station_id)
+            end_id = str(track.end_station_id)
+
+            # Add bidirectional edges (assuming tracks are bidirectional)
+            if start_id not in graph:
+                graph[start_id] = []
+            if end_id not in graph:
+                graph[end_id] = []
+
+            graph[start_id].append((end_id, track))
+            graph[end_id].append((start_id, track))
+
+        return graph
+
+    def combine_track_geometries(self, tracks: list[Track]) -> list[tuple[float, float]]:
+        """Combine the geometries of multiple tracks into a single coordinate sequence.
+
+        Assumes tracks are in order and form a continuous path.
+        """
+        if not tracks:
+            return []
+
+        combined_coords = []
+
+        for i, track in enumerate(tracks):
+            # Extract coordinates from track geometry
+            coords = self._extract_coordinates_from_track(track)
+
+            if i == 0:
+                # First track: add all coordinates
+                combined_coords.extend(coords)
+            else:
+                # Subsequent tracks: skip the first coordinate (shared with previous track)
+                combined_coords.extend(coords[1:])
+
+        return combined_coords
+
+    def _extract_coordinates_from_track(self, track: Track) -> list[tuple[float, float]]:
+        """Extract coordinate list from a track's geometry."""
+        # Convert WKT string to WKTElement, then to shapely geometry
+        from geoalchemy2.elements import WKTElement
+        from geoalchemy2.shape import to_shape
+
+        try:
+            wkt_element = WKTElement(track.track_geometry)
+            geom = to_shape(wkt_element)
+            if hasattr(geom, 'coords'):
+                # For LineString, coords returns [(x, y), ...] where x=lon, y=lat
+                # Convert to (lat, lon)
+                return [(coord[1], coord[0]) for coord in geom.coords]
+        except Exception:
+            pass
+
+        return []
+
     @staticmethod
     def _ensure_uuid(value: UUID | str) -> UUID:
         if isinstance(value, UUID):
@@ -30,7 +126,8 @@ class TrackRepository(BaseRepository[Track]):
     @staticmethod
     def _line_string(coordinates: list[tuple[float, float]]) -> WKTElement:
         if len(coordinates) < 2:
-            raise ValueError("Track geometry requires at least two coordinate pairs")
+            raise ValueError(
+                "Track geometry requires at least two coordinate pairs")
         parts = [f"{lon} {lat}" for lat, lon in coordinates]
         return WKTElement(f"LINESTRING({', '.join(parts)})", srid=4326)
 
@@ -38,6 +135,7 @@ class TrackRepository(BaseRepository[Track]):
         coordinates = list(data.coordinates)
         geometry = self._line_string(coordinates)
         track = Track(
+            osm_id=data.osm_id,
             name=data.name,
             start_station_id=self._ensure_uuid(data.start_station_id),
             end_station_id=self._ensure_uuid(data.end_station_id),
@@ -49,3 +147,26 @@ class TrackRepository(BaseRepository[Track]):
         )
         self.session.add(track)
         return track
+
+    def update(self, track: Track, payload: TrackUpdate) -> Track:
+        if payload.start_station_id is not None:
+            track.start_station_id = self._ensure_uuid(
+                payload.start_station_id)
+        if payload.end_station_id is not None:
+            track.end_station_id = self._ensure_uuid(payload.end_station_id)
+        if payload.coordinates is not None:
+            track.track_geometry = self._line_string(
+                list(payload.coordinates))  # type: ignore[assignment]
+        if payload.osm_id is not None:
+            track.osm_id = payload.osm_id
+        if payload.name is not None:
+            track.name = payload.name
+        if payload.length_meters is not None:
+            track.length_meters = payload.length_meters
+        if payload.max_speed_kph is not None:
+            track.max_speed_kph = payload.max_speed_kph
+        if payload.is_bidirectional is not None:
+            track.is_bidirectional = payload.is_bidirectional
+        if payload.status is not None:
+            track.status = payload.status
+        return track

backend/app/services/combined_tracks.py

@@ -0,0 +1,79 @@
+from __future__ import annotations
+
+"""Application services for combined track operations."""
+
+from sqlalchemy.orm import Session
+
+from backend.app.models import CombinedTrackCreate, CombinedTrackModel
+from backend.app.repositories import CombinedTrackRepository, TrackRepository
+
+
+def create_combined_track(
+    session: Session, start_station_id: str, end_station_id: str
+) -> CombinedTrackModel | None:
+    """Create a combined track between two stations using pathfinding.
+
+    Returns the created combined track, or None if no path exists or
+    a combined track already exists between these stations.
+    """
+    combined_track_repo = CombinedTrackRepository(session)
+    track_repo = TrackRepository(session)
+
+    # Check if combined track already exists
+    if combined_track_repo.exists_between_stations(start_station_id, end_station_id):
+        return None
+
+    # Find path between stations
+    path_tracks = track_repo.find_path_between_stations(
+        start_station_id, end_station_id)
+    if not path_tracks:
+        return None
+
+    # Combine geometries
+    combined_coords = track_repo.combine_track_geometries(path_tracks)
+    if len(combined_coords) < 2:
+        return None
+
+    # Calculate total length
+    total_length = sum(track.length_meters or 0 for track in path_tracks)
+
+    # Get max speed (use the minimum speed of all tracks)
+    max_speeds = [
+        track.max_speed_kph for track in path_tracks if track.max_speed_kph]
+    max_speed = min(max_speeds) if max_speeds else None
+
+    # Get constituent track IDs
+    constituent_track_ids = [str(track.id) for track in path_tracks]
+
+    # Create combined track
+    create_data = CombinedTrackCreate(
+        start_station_id=start_station_id,
+        end_station_id=end_station_id,
+        coordinates=combined_coords,
+        constituent_track_ids=constituent_track_ids,
+        length_meters=total_length if total_length > 0 else None,
+        max_speed_kph=max_speed,
+        status="operational",
+    )
+
+    combined_track = combined_track_repo.create(create_data)
+    session.commit()
+
+    return CombinedTrackModel.model_validate(combined_track)
+
+
+def get_combined_track(session: Session, combined_track_id: str) -> CombinedTrackModel | None:
+    """Get a combined track by ID."""
+    try:
+        combined_track_repo = CombinedTrackRepository(session)
+        combined_track = combined_track_repo.get(combined_track_id)
+        return CombinedTrackModel.model_validate(combined_track)
+    except LookupError:
+        return None
+
+
+def list_combined_tracks(session: Session) -> list[CombinedTrackModel]:
+    """List all combined tracks."""
+    combined_track_repo = CombinedTrackRepository(session)
+    combined_tracks = combined_track_repo.list_all()
+    return [CombinedTrackModel.model_validate(ct) for ct in combined_tracks]

backend/app/services/tracks.py

@@ -0,0 +1,106 @@
+from __future__ import annotations
+
+"""Service layer for primary track management operations."""
+
+from typing import Iterable
+
+from sqlalchemy.exc import IntegrityError
+from sqlalchemy.orm import Session
+
+from backend.app.models import CombinedTrackModel, TrackCreate, TrackModel, TrackUpdate
+from backend.app.repositories import CombinedTrackRepository, TrackRepository
+
+
+def list_tracks(session: Session) -> list[TrackModel]:
+    repo = TrackRepository(session)
+    tracks = repo.list_all()
+    return [TrackModel.model_validate(track) for track in tracks]
+
+
+def get_track(session: Session, track_id: str) -> TrackModel | None:
+    repo = TrackRepository(session)
+    track = repo.get(track_id)
+    if track is None:
+        return None
+    return TrackModel.model_validate(track)
+
+
+def create_track(session: Session, payload: TrackCreate) -> TrackModel:
+    repo = TrackRepository(session)
+    try:
+        track = repo.create(payload)
+        session.commit()
+    except IntegrityError as exc:
+        session.rollback()
+        raise ValueError(
+            "Track with the same station pair already exists") from exc
+
+    return TrackModel.model_validate(track)
+
+
+def update_track(session: Session, track_id: str, payload: TrackUpdate) -> TrackModel | None:
+    repo = TrackRepository(session)
+    track = repo.get(track_id)
+    if track is None:
+        return None
+
+    repo.update(track, payload)
+    session.commit()
+
+    return TrackModel.model_validate(track)
+
+
+def delete_track(session: Session, track_id: str, regenerate: bool = False) -> bool:
+    repo = TrackRepository(session)
+    track = repo.get(track_id)
+    if track is None:
+        return False
+
+    start_station_id = str(track.start_station_id)
+    end_station_id = str(track.end_station_id)
+
+    session.delete(track)
+    session.commit()
+
+    if regenerate:
+        regenerate_combined_tracks(session, [start_station_id, end_station_id])
+
+    return True
+
+
+def regenerate_combined_tracks(session: Session, station_ids: Iterable[str]) -> list[CombinedTrackModel]:
+    combined_repo = CombinedTrackRepository(session)
+
+    station_id_set = set(station_ids)
+    if not station_id_set:
+        return []
+
+    # Remove combined tracks touching these stations
+    for combined in combined_repo.list_all():
+        if {str(combined.start_station_id), str(combined.end_station_id)} & station_id_set:
+            session.delete(combined)
+
+    session.commit()
+
+    # Rebuild combined tracks between affected station pairs
+    from backend.app.services.combined_tracks import create_combined_track
+
+    regenerated: list[CombinedTrackModel] = []
+    station_list = list(station_id_set)
+    for i in range(len(station_list)):
+        for j in range(i + 1, len(station_list)):
+            result = create_combined_track(
+                session, station_list[i], station_list[j])
+            if result is not None:
+                regenerated.append(result)
+    return regenerated
+
+
+__all__ = [
+    "list_tracks",
+    "get_track",
+    "create_track",
+    "update_track",
+    "delete_track",
+    "regenerate_combined_tracks",
+]

backend/migrations/versions/63d02d67b39e_add_osm_id_to_tracks.py

@@ -0,0 +1,19 @@
+"""Template for new Alembic migration scripts."""
+
+from __future__ import annotations
+import sqlalchemy as sa
+from alembic import op
+
+revision = '63d02d67b39e'
+down_revision = '20251011_01'
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.add_column('tracks', sa.Column(
+        'osm_id', sa.String(length=32), nullable=True))
+
+
+def downgrade() -> None:
+    op.drop_column('tracks', 'osm_id')

backend/migrations/versions/e7d4bb03da04_add_combined_tracks_table.py

@@ -0,0 +1,75 @@
+"""Template for new Alembic migration scripts."""
+
+from __future__ import annotations
+from sqlalchemy.dialects import postgresql
+from geoalchemy2.types import Geometry
+import sqlalchemy as sa
+from alembic import op
+
+revision = 'e7d4bb03da04'
+down_revision = '63d02d67b39e'
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "combined_tracks",
+        sa.Column(
+            "id",
+            postgresql.UUID(as_uuid=True),
+            primary_key=True,
+            server_default=sa.text("gen_random_uuid()"),
+        ),
+        sa.Column("name", sa.String(length=128), nullable=True),
+        sa.Column("start_station_id", postgresql.UUID(
+            as_uuid=True), nullable=False),
+        sa.Column("end_station_id", postgresql.UUID(
+            as_uuid=True), nullable=False),
+        sa.Column("length_meters", sa.Numeric(10, 2), nullable=True),
+        sa.Column("max_speed_kph", sa.Integer(), nullable=True),
+        sa.Column(
+            "is_bidirectional",
+            sa.Boolean(),
+            nullable=False,
+            server_default=sa.text("true"),
+        ),
+        sa.Column(
+            "status", sa.String(length=32), nullable=False, server_default="planned"
+        ),
+        sa.Column(
+            "combined_geometry",
+            Geometry(geometry_type="LINESTRING", srid=4326),
+            nullable=False,
+        ),
+        sa.Column("constituent_track_ids", sa.Text(), nullable=False),
+        sa.Column(
+            "created_at",
+            sa.DateTime(timezone=True),
+            server_default=sa.text("timezone('utc', now())"),
+            nullable=False,
+        ),
+        sa.Column(
+            "updated_at",
+            sa.DateTime(timezone=True),
+            server_default=sa.text("timezone('utc', now())"),
+            nullable=False,
+        ),
+        sa.ForeignKeyConstraint(
+            ["start_station_id"], ["stations.id"], ondelete="RESTRICT"
+        ),
+        sa.ForeignKeyConstraint(
+            ["end_station_id"], ["stations.id"], ondelete="RESTRICT"
+        ),
+        sa.UniqueConstraint(
+            "start_station_id", "end_station_id", name="uq_combined_tracks_station_pair"
+        ),
+    )
+    op.create_index(
+        "ix_combined_tracks_geometry", "combined_tracks", ["combined_geometry"], postgresql_using="gist"
+    )
+
+
+def downgrade() -> None:
+    op.drop_index("ix_combined_tracks_geometry", table_name="combined_tracks")
+    op.drop_table("combined_tracks")

backend/scripts/osm_refresh.py

@@ -9,12 +9,7 @@ from pathlib import Path
 from typing import Callable, Sequence
 
 from backend.app.core.osm_config import DEFAULT_REGIONS
-from backend.scripts import (
+from backend.scripts import stations_import, stations_load, tracks_import, tracks_load
-    stations_import,
-    stations_load,
-    tracks_import,
-    tracks_load,
-)
 
 
 @dataclass(slots=True)

backend/scripts/tracks_load.py

@@ -22,6 +22,7 @@ from backend.app.repositories import StationRepository, TrackRepository
 @dataclass(slots=True)
 class ParsedTrack:
     coordinates: list[tuple[float, float]]
+    osm_id: str | None = None
     name: str | None = None
     length_meters: float | None = None
     max_speed_kph: float | None = None
@@ -97,7 +98,8 @@ def _parse_track_entries(entries: Iterable[Mapping[str, Any]]) -> list[ParsedTra
         processed_coordinates: list[tuple[float, float]] = []
         for pair in coordinates:
             if not isinstance(pair, Sequence) or len(pair) != 2:
-                raise ValueError(f"Invalid coordinate pair {pair!r} in track entry")
+                raise ValueError(
+                    f"Invalid coordinate pair {pair!r} in track entry")
             lat, lon = pair
             processed_coordinates.append((float(lat), float(lon)))
 
@@ -106,10 +108,12 @@ def _parse_track_entries(entries: Iterable[Mapping[str, Any]]) -> list[ParsedTra
         max_speed = _safe_float(entry.get("maxSpeedKph"))
         status = entry.get("status", "operational")
         is_bidirectional = entry.get("isBidirectional", True)
+        osm_id = entry.get("osmId")
 
         parsed.append(
             ParsedTrack(
                 coordinates=processed_coordinates,
+                osm_id=str(osm_id) if osm_id else None,
                 name=str(name) if name else None,
                 length_meters=length,
                 max_speed_kph=max_speed,
@@ -133,6 +137,12 @@ def load_tracks(tracks: Iterable[ParsedTrack], commit: bool = True) -> int:
         }
 
         for track_data in tracks:
+            # Skip if track with this OSM ID already exists
+            if track_data.osm_id and track_repo.exists_by_osm_id(track_data.osm_id):
+                print(
+                    f"Skipping track {track_data.osm_id} - already exists by OSM ID")
+                continue
+
             start_station = _nearest_station(
                 track_data.coordinates[0],
                 station_index,
@@ -145,13 +155,19 @@ def load_tracks(tracks: Iterable[ParsedTrack], commit: bool = True) -> int:
             )
 
             if not start_station or not end_station:
+                print(
+                    f"Skipping track {track_data.osm_id} - no start/end stations found")
                 continue
 
             if start_station.id == end_station.id:
+                print(
+                    f"Skipping track {track_data.osm_id} - start and end stations are the same")
                 continue
 
             pair = (start_station.id, end_station.id)
             if pair in existing_pairs:
+                print(
+                    f"Skipping track {track_data.osm_id} - station pair {pair} already exists")
                 continue
 
             length = track_data.length_meters or _polyline_length(
@@ -163,6 +179,7 @@ def load_tracks(tracks: Iterable[ParsedTrack], commit: bool = True) -> int:
                 else None
             )
             create_schema = TrackCreate(
+                osm_id=track_data.osm_id,
                 name=track_data.name,
                 start_station_id=start_station.id,
                 end_station_id=end_station.id,
@@ -193,7 +210,8 @@ def _nearest_station(
     best_station: StationRef | None = None
     best_distance = math.inf
     for station in stations:
-        distance = _haversine(coordinate, (station.latitude, station.longitude))
+        distance = _haversine(
+            coordinate, (station.latitude, station.longitude))
         if distance < best_distance:
             best_station = station
             best_distance = distance

backend/tests/test_combined_tracks.py

@@ -0,0 +1,166 @@
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+from datetime import datetime, timezone
+from typing import Any, List
+from uuid import uuid4
+
+import pytest
+
+from backend.app.models import CombinedTrackModel
+from backend.app.repositories.combined_tracks import CombinedTrackRepository
+from backend.app.repositories.tracks import TrackRepository
+from backend.app.services.combined_tracks import create_combined_track
+
+
+@dataclass
+class DummySession:
+    added: List[Any] = field(default_factory=list)
+    scalars_result: List[Any] = field(default_factory=list)
+    scalar_result: Any = None
+    statements: List[Any] = field(default_factory=list)
+    committed: bool = False
+    rolled_back: bool = False
+    closed: bool = False
+
+    def add(self, instance: Any) -> None:
+        self.added.append(instance)
+
+    def add_all(self, instances: list[Any]) -> None:
+        self.added.extend(instances)
+
+    def scalars(self, statement: Any) -> list[Any]:
+        self.statements.append(statement)
+        return list(self.scalars_result)
+
+    def scalar(self, statement: Any) -> Any:
+        self.statements.append(statement)
+        return self.scalar_result
+
+    def flush(
+        self, _objects: list[Any] | None = None
+    ) -> None:  # pragma: no cover - optional
+        return None
+
+    def commit(self) -> None:  # pragma: no cover - optional
+        self.committed = True
+
+    def rollback(self) -> None:  # pragma: no cover - optional
+        self.rolled_back = True
+
+    def close(self) -> None:  # pragma: no cover - optional
+        self.closed = True
+
+
+def _now() -> datetime:
+    return datetime.now(timezone.utc)
+
+
+def test_combined_track_model_round_trip() -> None:
+    timestamp = _now()
+    combined_track = CombinedTrackModel(
+        id="combined-track-1",
+        start_station_id="station-1",
+        end_station_id="station-2",
+        length_meters=3000.0,
+        max_speed_kph=100,
+        status="operational",
+        is_bidirectional=True,
+        coordinates=[(52.52, 13.405), (52.6, 13.5), (52.7, 13.6)],
+        constituent_track_ids=["track-1", "track-2"],
+        created_at=timestamp,
+        updated_at=timestamp,
+    )
+    assert combined_track.length_meters == 3000.0
+    assert combined_track.start_station_id != combined_track.end_station_id
+    assert len(combined_track.coordinates) == 3
+    assert len(combined_track.constituent_track_ids) == 2
+
+
+def test_combined_track_repository_create() -> None:
+    """Test creating a combined track through the repository."""
+    session = DummySession()
+    repo = CombinedTrackRepository(session)  # type: ignore[arg-type]
+
+    # Create test data
+    from backend.app.models import CombinedTrackCreate
+
+    create_data = CombinedTrackCreate(
+        start_station_id="550e8400-e29b-41d4-a716-446655440000",
+        end_station_id="550e8400-e29b-41d4-a716-446655440001",
+        coordinates=[(52.52, 13.405), (52.6, 13.5)],
+        constituent_track_ids=["track-1"],
+        length_meters=1500.0,
+        max_speed_kph=120,
+        status="operational",
+    )
+
+    combined_track = repo.create(create_data)
+
+    assert combined_track.start_station_id is not None
+    assert combined_track.end_station_id is not None
+    assert combined_track.length_meters == 1500.0
+    assert combined_track.max_speed_kph == 120
+    assert combined_track.status == "operational"
+    assert session.added and session.added[0] is combined_track
+
+
+def test_combined_track_repository_exists_between_stations() -> None:
+    """Test checking if combined track exists between stations."""
+    session = DummySession()
+    repo = CombinedTrackRepository(session)  # type: ignore[arg-type]
+
+    # Initially should not exist (scalar_result is None by default)
+    assert not repo.exists_between_stations(
+        "550e8400-e29b-41d4-a716-446655440000",
+        "550e8400-e29b-41d4-a716-446655440001"
+    )
+
+    # Simulate existing combined track
+    session.scalar_result = True
+    assert repo.exists_between_stations(
+        "550e8400-e29b-41d4-a716-446655440000",
+        "550e8400-e29b-41d4-a716-446655440001"
+    )
+
+
+def test_combined_track_service_create_no_path() -> None:
+    """Test creating combined track when no path exists."""
+    # Mock session and repositories
+    session = DummySession()
+
+    # Mock TrackRepository to return no path
+    class MockTrackRepository:
+        def __init__(self, session):
+            pass
+
+        def find_path_between_stations(self, start_id, end_id):
+            return None
+
+    # Mock CombinedTrackRepository
+    class MockCombinedTrackRepository:
+        def __init__(self, session):
+            pass
+
+        def exists_between_stations(self, start_id, end_id):
+            return False
+
+    # Patch the service to use mock repositories
+    import backend.app.services.combined_tracks as service_module
+    original_track_repo = service_module.TrackRepository
+    original_combined_repo = service_module.CombinedTrackRepository
+
+    service_module.TrackRepository = MockTrackRepository
+    service_module.CombinedTrackRepository = MockCombinedTrackRepository
+
+    try:
+        result = create_combined_track(
+            session,  # type: ignore[arg-type]
+            "550e8400-e29b-41d4-a716-446655440000",
+            "550e8400-e29b-41d4-a716-446655440001"
+        )
+        assert result is None
+    finally:
+        # Restore original classes
+        service_module.TrackRepository = original_track_repo
+        service_module.CombinedTrackRepository = original_combined_repo

backend/tests/test_tracks_api.py

@@ -0,0 +1,158 @@
+from __future__ import annotations
+
+from datetime import datetime, timezone
+from typing import Any
+
+import pytest
+from fastapi.testclient import TestClient
+
+from backend.app.api import tracks as tracks_api
+from backend.app.main import app
+from backend.app.models import CombinedTrackModel, TrackModel
+
+client = TestClient(app)
+
+
+def _track_model(track_id: str = "track-1") -> TrackModel:
+    now = datetime.now(timezone.utc)
+    return TrackModel(
+        id=track_id,
+        start_station_id="station-a",
+        end_station_id="station-b",
+        length_meters=None,
+        max_speed_kph=None,
+        status="planned",
+        coordinates=[(52.5, 13.4), (52.6, 13.5)],
+        is_bidirectional=True,
+        created_at=now,
+        updated_at=now,
+    )
+
+
+def _combined_model(track_id: str = "combined-1") -> CombinedTrackModel:
+    now = datetime.now(timezone.utc)
+    return CombinedTrackModel(
+        id=track_id,
+        start_station_id="station-a",
+        end_station_id="station-b",
+        length_meters=1000,
+        max_speed_kph=120,
+        status="operational",
+        coordinates=[(52.5, 13.4), (52.6, 13.5)],
+        constituent_track_ids=["track-1", "track-2"],
+        is_bidirectional=True,
+        created_at=now,
+        updated_at=now,
+    )
+
+
+def _authenticate() -> str:
+    response = client.post(
+        "/api/auth/login",
+        json={"username": "demo", "password": "railgame123"},
+    )
+    assert response.status_code == 200
+    return response.json()["accessToken"]
+
+
+def test_list_tracks(monkeypatch: pytest.MonkeyPatch) -> None:
+    token = _authenticate()
+    monkeypatch.setattr(tracks_api, "list_tracks", lambda db: [_track_model()])
+
+    response = client.get(
+        "/api/tracks",
+        headers={"Authorization": f"Bearer {token}"},
+    )
+    assert response.status_code == 200
+    payload = response.json()
+    assert isinstance(payload, list)
+    assert payload[0]["id"] == "track-1"
+
+
+def test_get_track_returns_404(monkeypatch: pytest.MonkeyPatch) -> None:
+    token = _authenticate()
+    monkeypatch.setattr(tracks_api, "get_track", lambda db, track_id: None)
+
+    response = client.get(
+        "/api/tracks/not-found",
+        headers={"Authorization": f"Bearer {token}"},
+    )
+    assert response.status_code == 404
+
+
+def test_create_track_calls_service(monkeypatch: pytest.MonkeyPatch) -> None:
+    token = _authenticate()
+    captured: dict[str, Any] = {}
+    payload = {
+        "startStationId": "station-a",
+        "endStationId": "station-b",
+        "coordinates": [[52.5, 13.4], [52.6, 13.5]],
+    }
+
+    def fake_create(db: Any, data: Any) -> TrackModel:
+        assert data.start_station_id == "station-a"
+        captured["payload"] = data
+        return _track_model("track-new")
+
+    monkeypatch.setattr(tracks_api, "create_track", fake_create)
+
+    response = client.post(
+        "/api/tracks",
+        json=payload,
+        headers={"Authorization": f"Bearer {token}"},
+    )
+    assert response.status_code == 201
+    body = response.json()
+    assert body["id"] == "track-new"
+    assert captured["payload"].end_station_id == "station-b"
+
+
+def test_delete_track_returns_404(monkeypatch: pytest.MonkeyPatch) -> None:
+    token = _authenticate()
+    monkeypatch.setattr(
+        tracks_api, "delete_track", lambda db, tid, regenerate=False: False
+    )
+
+    response = client.delete(
+        "/api/tracks/missing",
+        headers={"Authorization": f"Bearer {token}"},
+    )
+    assert response.status_code == 404
+
+
+def test_delete_track_success(monkeypatch: pytest.MonkeyPatch) -> None:
+    token = _authenticate()
+    seen: dict[str, Any] = {}
+
+    def fake_delete(db: Any, track_id: str, regenerate: bool = False) -> bool:
+        seen["track_id"] = track_id
+        seen["regenerate"] = regenerate
+        return True
+
+    monkeypatch.setattr(tracks_api, "delete_track", fake_delete)
+
+    response = client.delete(
+        "/api/tracks/track-99",
+        params={"regenerate": "true"},
+        headers={"Authorization": f"Bearer {token}"},
+    )
+
+    assert response.status_code == 204
+    assert seen["track_id"] == "track-99"
+    assert seen["regenerate"] is True
+
+
+def test_list_combined_tracks(monkeypatch: pytest.MonkeyPatch) -> None:
+    token = _authenticate()
+    monkeypatch.setattr(
+        tracks_api, "list_combined_tracks", lambda db: [_combined_model()]
+    )
+
+    response = client.get(
+        "/api/tracks/combined",
+        headers={"Authorization": f"Bearer {token}"},
+    )
+    assert response.status_code == 200
+    payload = response.json()
+    assert len(payload) == 1
+    assert payload[0]["id"] == "combined-1"

docs/architecture.md

@@ -70,8 +70,8 @@ The system interacts with:
 
 - User registration and authentication
 - Railway network building and management
-- Train scheduling and simulation
 - Map visualization and interaction
+- Train scheduling and simulation
 - Leaderboards and user profiles
 
 **Out of Scope:**

frontend/package-lock.json

@@ -65,6 +65,7 @@
       "integrity": "sha512-2BCOP7TN8M+gVDj7/ht3hsaO/B/n5oDbiAyyvnRlNOs+u1o+JWNYTQrmpuNp1/Wq2gcFrI01JAW+paEKDMx/CA==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@babel/code-frame": "^7.27.1",
         "@babel/generator": "^7.28.3",
@@ -1425,6 +1426,7 @@
       "integrity": "sha512-2Q7WS25j4pS1cS8yw3d6buNCVJukOTeQ39bAnwR6sOJbaxvyCGebzTMypDFN82CxBLnl+lSWVdCCWbRY6y9yZQ==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "undici-types": "~6.21.0"
       }
@@ -1442,6 +1444,7 @@
       "integrity": "sha512-RFA/bURkcKzx/X9oumPG9Vp3D3JUgus/d0b67KB0t5S/raciymilkOa66olh78MUI92QLbEJevO7rvqU/kjwKA==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@types/prop-types": "*",
         "csstype": "^3.0.2"
@@ -1493,6 +1496,7 @@
       "integrity": "sha512-n1H6IcDhmmUEG7TNVSspGmiHHutt7iVKtZwRppD7e04wha5MrkV1h3pti9xQLcCMt6YWsncpoT0HMjkH1FNwWQ==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@typescript-eslint/scope-manager": "8.46.0",
         "@typescript-eslint/types": "8.46.0",
@@ -1829,6 +1833,7 @@
       "integrity": "sha512-NZyJarBfL7nWwIq+FDL6Zp/yHEhePMNnnJ0y3qfieCrmNvYct8uvtiV41UvlSe6apAfk0fY1FbWx+NwfmpvtTg==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "bin": {
         "acorn": "bin/acorn"
       },
@@ -2202,6 +2207,7 @@
         }
       ],
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "baseline-browser-mapping": "^2.8.9",
         "caniuse-lite": "^1.0.30001746",
@@ -2852,6 +2858,7 @@
       "deprecated": "This version is no longer supported. Please see https://eslint.org/version-support for other options.",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@eslint-community/eslint-utils": "^4.2.0",
         "@eslint-community/regexpp": "^4.6.1",
@@ -4538,7 +4545,8 @@
       "version": "1.9.4",
       "resolved": "https://registry.npmjs.org/leaflet/-/leaflet-1.9.4.tgz",
       "integrity": "sha512-nxS1ynzJOmOlHp+iL3FyWqK89GtNL8U8rvlMOsQdTTssxZwCXh8N2NB3GDQOL+YR3XnWyZAxwQixURb+FA74PA==",
-      "license": "BSD-2-Clause"
+      "license": "BSD-2-Clause",
+      "peer": true
     },
     "node_modules/levn": {
       "version": "0.4.1",
@@ -5323,6 +5331,7 @@
       "resolved": "https://registry.npmjs.org/react/-/react-18.3.1.tgz",
       "integrity": "sha512-wS+hAgJShR0KhEvPJArfuPVN1+Hz1t0Y6n5jLrGQbkb4urgPE/0Rve+1kMB1v/oWgHgm4WIcV+i7F2pTVj+2iQ==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "loose-envify": "^1.1.0"
       },
@@ -5335,6 +5344,7 @@
       "resolved": "https://registry.npmjs.org/react-dom/-/react-dom-18.3.1.tgz",
       "integrity": "sha512-5m4nQKp+rZRb09LNH59GM4BxTh9251/ylbKIbpe7TpGxfJ+9kv6BLkLBXIjjspbgbnIBNqlI23tRnTWT0snUIw==",
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "loose-envify": "^1.1.0",
         "scheduler": "^0.23.2"
@@ -6240,6 +6250,7 @@
       "integrity": "sha512-jl1vZzPDinLr9eUt3J/t7V6FgNEw9QjvBPdysz9KfQDD41fQrC2Y4vKQdiaUpFT4bXlb1RHhLpp8wtm6M5TgSw==",
       "dev": true,
       "license": "Apache-2.0",
+      "peer": true,
       "bin": {
         "tsc": "bin/tsc",
         "tsserver": "bin/tsserver"
@@ -6328,6 +6339,7 @@
       "integrity": "sha512-j3lYzGC3P+B5Yfy/pfKNgVEg4+UtcIJcVRt2cDjIOmhLourAqPqf8P7acgxeiSgUB7E3p2P8/3gNIgDLpwzs4g==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "esbuild": "^0.21.3",
         "postcss": "^8.4.43",

frontend/src/App.tsx

@@ -19,11 +19,13 @@ function App(): JSX.Element {
     startId: string | null;
     endId: string | null;
   }>({ startId: null, endId: null });
+  const [selectedTrackId, setSelectedTrackId] = useState<string | null>(null);
 
   useEffect(() => {
     if (status !== 'success' || !data?.stations.length) {
       setFocusedStationId(null);
       setRouteSelection({ startId: null, endId: null });
+      setSelectedTrackId(null);
       return;
     }
 
@@ -92,8 +94,16 @@ function App(): JSX.Element {
     return stationById.get(focusedStationId) ?? null;
   }, [data, focusedStationId, stationById]);
 
+  const selectedTrack = useMemo(() => {
+    if (!data || !selectedTrackId) {
+      return null;
+    }
+    return data.tracks.find((track) => track.id === selectedTrackId) ?? null;
+  }, [data, selectedTrackId]);
+
   const handleStationSelection = (stationId: string) => {
     setFocusedStationId(stationId);
+    setSelectedTrackId(null);
     setRouteSelection((current) => {
       if (!current.startId || (current.startId && current.endId)) {
         return { startId: stationId, endId: null };
@@ -111,6 +121,16 @@ function App(): JSX.Element {
     setRouteSelection({ startId: null, endId: null });
   };
 
+  const handleCreateTrack = () => {
+    if (!routeSelection.startId || !routeSelection.endId) {
+      return;
+    }
+    // TODO: Implement track creation API call
+    alert(
+      `Creating track between ${stationById.get(routeSelection.startId)?.name} and ${stationById.get(routeSelection.endId)?.name}`
+    );
+  };
+
   return (
     <div className="app-shell">
       <header className="app-header">
@@ -146,7 +166,9 @@ function App(): JSX.Element {
                     startStationId={routeSelection.startId}
                     endStationId={routeSelection.endId}
                     routeSegments={routeSegments}
+                    selectedTrackId={selectedTrackId}
                     onStationClick={handleStationSelection}
+                    onTrackClick={setSelectedTrackId}
                   />
                 </div>
                 <div className="route-panel">
@@ -206,6 +228,19 @@ function App(): JSX.Element {
                       </ol>
                     </div>
                   )}
+                  {routeSelection.startId &&
+                    routeSelection.endId &&
+                    routeComputation.error && (
+                      <div className="route-panel__actions">
+                        <button
+                          type="button"
+                          className="primary-button"
+                          onClick={handleCreateTrack}
+                        >
+                          Create Track
+                        </button>
+                      </div>
+                    )}
                 </div>
                 <div className="grid">
                   <div>
@@ -318,6 +353,49 @@ function App(): JSX.Element {
                     </dl>
                   </div>
                 )}
+                {selectedTrack && (
+                  <div className="selected-track">
+                    <h3>Selected Track</h3>
+                    <dl>
+                      <div>
+                        <dt>Start Station</dt>
+                        <dd>
+                          {stationById.get(selectedTrack.startStationId)?.name ??
+                            'Unknown'}
+                        </dd>
+                      </div>
+                      <div>
+                        <dt>End Station</dt>
+                        <dd>
+                          {stationById.get(selectedTrack.endStationId)?.name ??
+                            'Unknown'}
+                        </dd>
+                      </div>
+                      <div>
+                        <dt>Length</dt>
+                        <dd>
+                          {selectedTrack.lengthMeters > 0
+                            ? `${(selectedTrack.lengthMeters / 1000).toFixed(2)} km`
+                            : 'N/A'}
+                        </dd>
+                      </div>
+                      <div>
+                        <dt>Max Speed</dt>
+                        <dd>{selectedTrack.maxSpeedKph} km/h</dd>
+                      </div>
+                      {selectedTrack.status && (
+                        <div>
+                          <dt>Status</dt>
+                          <dd>{selectedTrack.status}</dd>
+                        </div>
+                      )}
+                      <div>
+                        <dt>Bidirectional</dt>
+                        <dd>{selectedTrack.isBidirectional ? 'Yes' : 'No'}</dd>
+                      </div>
+                    </dl>
+                  </div>
+                )}
               </div>
             )}
           </section>

frontend/src/components/map/NetworkMap.tsx

@@ -19,7 +19,9 @@ interface NetworkMapProps {
   readonly startStationId?: string | null;
   readonly endStationId?: string | null;
   readonly routeSegments?: LatLngExpression[][];
+  readonly selectedTrackId?: string | null;
   readonly onStationClick?: (stationId: string) => void;
+  readonly onTrackClick?: (trackId: string) => void;
 }
 
 interface StationPosition {
@@ -36,7 +38,9 @@ export function NetworkMap({
   startStationId,
   endStationId,
   routeSegments = [],
+  selectedTrackId,
   onStationClick,
+  onTrackClick,
 }: NetworkMapProps): JSX.Element {
   const stationPositions = useMemo<StationPosition[]>(() => {
     return snapshot.stations.map((station) => ({
@@ -117,13 +121,43 @@ export function NetworkMap({
         url="https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png"
       />
       {focusedPosition ? <StationFocus position={focusedPosition} /> : null}
-      {trackSegments.map((segment, index) => (
+      {trackSegments.map((segment, index) => {
+        const track = snapshot.tracks[index];
+        const isSelected = track.id === selectedTrackId;
+        return (
           <Polyline
-          key={`track-${index}`}
+            key={`track-${track.id}`}
             positions={segment}
-          pathOptions={{ color: '#334155', weight: 3, opacity: 0.8 }}
+            pathOptions={{
-        />
+              color: isSelected ? '#3b82f6' : '#334155',
-      ))}
+              weight: isSelected ? 5 : 3,
+              opacity: 0.8,
+            }}
+            eventHandlers={{
+              click: () => {
+                onTrackClick?.(track.id);
+              },
+            }}
+          >
+            <Tooltip>
+              {track.startStationId} → {track.endStationId}
+              <br />
+              Length:{' '}
+              {track.lengthMeters > 0
+                ? `${(track.lengthMeters / 1000).toFixed(1)} km`
+                : 'N/A'}
+              <br />
+              Max Speed: {track.maxSpeedKph} km/h
+              {track.status && (
+                <>
+                  <br />
+                  Status: {track.status}
+                </>
+              )}
+            </Tooltip>
+          </Polyline>
+        );
+      })}
       {routeSegments.map((segment, index) => (
         <Polyline
           key={`route-${index}`}

frontend/src/styles/global.css

@@ -266,6 +266,12 @@ body {
   margin: 0;
 }
 
+.route-panel__actions {
+  margin-top: 1rem;
+  display: flex;
+  gap: 0.75rem;
+}
+
 .selected-station {
   margin-top: 1rem;
   padding: 1rem 1.25rem;
@@ -305,6 +311,45 @@ body {
   color: rgba(226, 232, 240, 0.92);
 }
 
+.selected-track {
+  margin-top: 1rem;
+  padding: 1rem 1.25rem;
+  border-radius: 12px;
+  border: 1px solid rgba(59, 130, 246, 0.35);
+  background: rgba(37, 99, 235, 0.18);
+  display: grid;
+  gap: 0.75rem;
+}
+
+.selected-track h3 {
+  color: rgba(226, 232, 240, 0.9);
+  font-size: 1.1rem;
+}
+
+.selected-track dl {
+  display: grid;
+  gap: 0.45rem;
+}
+
+.selected-track dl > div {
+  display: flex;
+  align-items: baseline;
+  justify-content: space-between;
+  gap: 0.75rem;
+}
+
+.selected-track dt {
+  font-size: 0.8rem;
+  text-transform: uppercase;
+  letter-spacing: 0.08em;
+  color: rgba(226, 232, 240, 0.6);
+}
+
+.selected-track dd {
+  font-size: 0.95rem;
+  color: rgba(226, 232, 240, 0.92);
+}
+
 @media (min-width: 768px) {
   .snapshot-layout {
     gap: 2rem;

scripts/init_demo_db.py

@@ -62,13 +62,23 @@ def check_database_url():
     print(f"Using database: {database_url}")
 
 
-def run_command(cmd, cwd=None, description=""):
+def run_command(cmd, cwd=None, description="", env=None):
     """Run a shell command and return the result."""
     print(f"\n>>> {description}")
     print(f"Running: {' '.join(cmd)}")
     try:
-        result = subprocess.run(cmd, cwd=cwd, check=True,
+        env_vars = os.environ.copy()
-                                capture_output=True, text=True)
+        if env:
+            env_vars.update(env)
+        env_vars.setdefault("PYTHONPATH", "/app")
+        result = subprocess.run(
+            cmd,
+            cwd=cwd,
+            check=True,
+            capture_output=True,
+            text=True,
+            env=env_vars,
+        )
         if result.stdout:
             print(result.stdout)
         return result
@@ -86,7 +96,7 @@ def run_migrations():
     run_command(
         ['alembic', 'upgrade', 'head'],
         cwd='backend',
-        description="Running database migrations"
+        description="Running database migrations",
     )