fix(admin): return day column as text in getCampaignProgression

`postgres.js` returns PG `date` as a string, not a `Date`, which broke
the tRPC serializer (`value.toISOString is not a function`). Use
`to_char(submitted_at, 'YYYY-MM-DD')` to force a text column and drop the
now-unused `toIsoDay` helper.

Author: LucasCharrier

packages/app/src/server/api/routers/__tests__/adminStats.test.ts

@@ -16,7 +16,9 @@ type SelectChain = {
 	orderBy: ReturnType<typeof vi.fn>;
 };
 
-function buildDb(rows: Array<{ day: Date; year: number; count: number }> = []) {
+function buildDb(
+	rows: Array<{ day: string; year: number; count: number }> = [],
+) {
 	const orderBy = vi.fn().mockResolvedValue(rows);
 	const chain: SelectChain = {
 		from: vi.fn().mockReturnThis(),
@@ -74,10 +76,10 @@ describe("adminStatsRouter.getCampaignProgression", () => {
 
 	it("groups points by year and computes a running cumulative total", async () => {
 		const db = buildDb([
-			{ day: new Date("2025-01-05T00:00:00Z"), year: 2025, count: 10 },
-			{ day: new Date("2025-01-06T00:00:00Z"), year: 2025, count: 5 },
-			{ day: new Date("2026-01-05T00:00:00Z"), year: 2026, count: 20 },
-			{ day: new Date("2026-01-08T00:00:00Z"), year: 2026, count: 3 },
+			{ day: "2025-01-05", year: 2025, count: 10 },
+			{ day: "2025-01-06", year: 2025, count: 5 },
+			{ day: "2026-01-05", year: 2026, count: 20 },
+			{ day: "2026-01-08", year: 2026, count: 3 },
 		]);
 		const { adminStatsRouter } = await import("../adminStats");
 		const caller = adminStatsRouter.createCaller({

packages/app/src/server/api/routers/adminStats.ts

@@ -18,17 +18,7 @@ import { COMPANY_SIZE_RANGES } from "~/modules/domain";
 import { adminProcedure, createTRPCRouter } from "~/server/api/trpc";
 import { companies, declarations } from "~/server/db/schema";
 
-type AggregatedRow = { day: Date; year: number; count: number };
-
-/**
- * Convert a PG `date` cast (returned as `Date` in UTC midnight) to an ISO
- * YYYY-MM-DD string suitable for a cross-year chart axis.
- */
-function toIsoDay(value: Date): string {
-	const iso = value.toISOString();
-	// `2026-02-15T00:00:00.000Z` → `2026-02-15`
-	return iso.slice(0, 10);
-}
+type AggregatedRow = { day: string; year: number; count: number };
 
 /**
  * Walk the per-day rows (already ordered by (year, day) ASC) and produce one
@@ -44,7 +34,7 @@ function buildSeries(rows: AggregatedRow[]): CampaignProgressionSeries[] {
 		const list = byYear.get(year) ?? [];
 		const previous = list[list.length - 1]?.cumulative ?? 0;
 		list.push({
-			day: toIsoDay(row.day),
+			day: row.day,
 			cumulative: previous + row.count,
 		});
 		byYear.set(year, list);
@@ -84,7 +74,10 @@ export const adminStatsRouter = createTRPCRouter({
 				);
 			}
 
-			const dayExpr = sql<Date>`date_trunc('day', ${declarations.submittedAt})::date`;
+			// `to_char` forces a text return so the postgres.js driver hands back
+			// a plain ISO string (YYYY-MM-DD) rather than a `Date` that would then
+			// need timezone-safe formatting.
+			const dayExpr = sql<string>`to_char(${declarations.submittedAt}, 'YYYY-MM-DD')`;
 
 			const query = ctx.db
 				.select({