Ensure a unique ID for supply routes.

List indexes are not a reliable list key unless the list is static.
Indexes will be reused when games are loaded, which prevents the state
from updating reliably.

Fixes https://github.com/dcs-liberation/dcs_liberation/issues/2167

client/src/api/_liberationApi.ts

@@ -428,6 +428,7 @@ export type Tgo = {
   sidc: string;
 };
 export type SupplyRoute = {
+  id: string;
   points: LatLng[];
   front_active: boolean;
   is_sea: boolean;

client/src/components/supplyrouteslayer/SupplyRoutesLayer.tsx

@@ -7,8 +7,8 @@ export default function SupplyRoutesLayer() {
   const routes = useAppSelector(selectSupplyRoutes).routes;
   return (
     <LayerGroup>
-      {routes.map((route, idx) => {
-        return <SupplyRoute key={idx} route={route} />;
+      {routes.map((route) => {
+        return <SupplyRoute key={route.id} route={route} />;
       })}
     </LayerGroup>
   );

game/server/supplyroutes/models.py

@@ -1,6 +1,8 @@
 from __future__ import annotations
 
+import uuid
 from typing import Any, TYPE_CHECKING
+from uuid import UUID
 
 from dcs import Point
 from pydantic import BaseModel
@@ -62,6 +64,7 @@ class TransportFinder:
 
 
 class SupplyRouteJs(BaseModel):
+    id: UUID
     points: list[LeafletPoint]
     front_active: bool
     is_sea: bool
@@ -76,6 +79,19 @@ class SupplyRouteJs(BaseModel):
         game: Game, a: ControlPoint, b: ControlPoint, points: list[Point], sea: bool
     ) -> SupplyRouteJs:
         return SupplyRouteJs(
+            # Although these are not persistent objects in the backend, the frontend
+            # needs unique IDs for anything that it will use in a list. That means that
+            # any data that we expose as a list most likely needs a unique ID. List
+            # indexes are **not** sufficient as IDs across game loads, as any indexes
+            # that persist between games will not be updated in the UI.
+            #
+            # Generating a UUID for these ephemeral objects is awkward, but does not
+            # cause any issues since the only thing the ID is used for is to
+            # disambiguate objects across save games.
+            #
+            # https://reactjs.org/docs/lists-and-keys.html#keys
+            # https://github.com/dcs-liberation/dcs_liberation/issues/2167
+            id=uuid.uuid4(),
             points=[p.latlng() for p in points],
             front_active=not sea and a.front_is_active(b),
             is_sea=sea,