fix(prediction): correct lon mapping

src/lib/api/predictions.ts

@@ -1,18 +1,6 @@
 import { api } from './client';
 import type { FlightParameters, RawPrediction } from '$domain';
 
-/**
- * GFS datasets are published every 6 hours with a ~6 hour processing lag.
- * Round down to the most recent available slot.
- */
-export function getLatestDataset(now: Date = new Date()): string {
-	// const rounded = new Date(now);
-	// rounded.setUTCHours(Math.floor(rounded.getUTCHours() / 6) * 6, 0, 0, 0);
-	// rounded.setUTCHours(rounded.getUTCHours() - 6);
-	// return rounded.toISOString();
-	return "2025-04-06T00:00:00Z";
-}
-
 export function buildLaunchDateTime(date: string, time: string): string {
 	const fullTime = time.split(':').length === 2 ? `${time}:00` : time;
 	return new Date(`${date}T${fullTime}Z`).toISOString();
@@ -24,11 +12,17 @@ export interface PredictionResponse {
 
 export const predictionsApi = {
 	run: (params: FlightParameters, launchDateTime: string) => {
-		const payload: FlightParameters & { launch_datetime: string } = {
-			...params,
-			dataset: params.dataset || getLatestDataset(),
+		// `dataset` carries only what the operator actually chose. It used to fall
+		// back to a client-side guess at which GFS run the server holds — and the
+		// guess had degenerated into a hardcoded 2025-04-06, over a year stale. The
+		// client cannot know which runs are stored; the predictor refuses one it
+		// does not have, so an unset value must stay unset and let the server pick.
+		const { dataset, ...rest } = params;
+		const payload = {
+			...rest,
+			...(dataset ? { dataset } : {}),
 			launch_datetime: launchDateTime,
-		};
+		} as FlightParameters & { launch_datetime: string };
 		if (payload.start_point === -1) delete payload.start_point;
 		return api.post<PredictionResponse>('/predictions/', payload);
 	},