refactor: deduplicate formatters and improve test mocks (#81)

- Consolidate duplicate date formatting utilities
- Use shared formatters across backend and frontend
- Clean up test mocks to use consistent test data
- Remove redundant formatting functions

backend/src/routes/export.ts

@@ -9,6 +9,7 @@ import { doseTracking, medications, shareTokens, userSettings } from "../db/sche
 import { getAnonymousUserId, requireAuth } from "../plugins/auth.js";
 import { env } from "../plugins/env.js";
 import type { AuthUser } from "../types/fastify.js";
+import { parseTakenByJson } from "../utils/scheduler-utils.js";
 
 const IMAGES_DIR = resolve(process.cwd(), "data/images");
 
@@ -125,17 +126,6 @@ async function getUserId(request: any, reply: any): Promise<number> {
 	return authUser.id;
 }
 
-// Parse takenByJson safely
-function parseTakenByJson(takenByJson: string | null | undefined): string[] {
-	if (!takenByJson) return [];
-	try {
-		const parsed = JSON.parse(takenByJson);
-		return Array.isArray(parsed) ? parsed.filter((s: unknown) => typeof s === "string" && s.trim()) : [];
-	} catch {
-		return [];
-	}
-}
-
 // Parse blisters from DB format to export format
 function parseBlistersForExport(
 	row: typeof medications.$inferSelect

backend/src/routes/medications.ts

@@ -9,7 +9,7 @@ import { doseTracking, medications } from "../db/schema.js";
 import { getAnonymousUserId, requireAuth } from "../plugins/auth.js";
 import { env } from "../plugins/env.js";
 import type { AuthUser } from "../types/fastify.js";
-import { parseLocalDateTime } from "../utils/scheduler-utils.js";
+import { parseBlisters, parseLocalDateTime, parseTakenByJson } from "../utils/scheduler-utils.js";
 
 const IMAGES_DIR = resolve(process.cwd(), "data/images");
 
@@ -34,36 +34,6 @@ const medicationSchema = z.object({
 	blisters: z.array(blisterSchema).min(1).max(12),
 });
 
-function zipBlisters(usage: number[], every: number[], start: string[]) {
-	const len = Math.min(usage.length, every.length, start.length);
-	const blisters: Array<{ usage: number; every: number; start: string }> = [];
-	for (let i = 0; i < len; i++) {
-		blisters.push({ usage: usage[i], every: every[i], start: start[i] });
-	}
-	return blisters;
-}
-
-function parseBlisters(row: typeof medications.$inferSelect) {
-	try {
-		const usage = JSON.parse(row.usageJson) as number[];
-		const every = JSON.parse(row.everyJson) as number[];
-		const start = JSON.parse(row.startJson) as string[];
-		return zipBlisters(usage, every, start);
-	} catch (_err) {
-		return [];
-	}
-}
-
-function parseTakenByJson(takenByJson: string | null | undefined): string[] {
-	if (!takenByJson) return [];
-	try {
-		const parsed = JSON.parse(takenByJson);
-		return Array.isArray(parsed) ? parsed.filter((s: unknown) => typeof s === "string" && s.trim()) : [];
-	} catch {
-		return [];
-	}
-}
-
 export async function medicationRoutes(app: FastifyInstance) {
 	// All medication routes require auth
 	app.addHook("preHandler", requireAuth);

backend/src/routes/share.ts

@@ -7,6 +7,7 @@ import { medications, shareTokens, userSettings, users } from "../db/schema.js";
 import { getAnonymousUserId, requireAuth } from "../plugins/auth.js";
 import { env } from "../plugins/env.js";
 import type { AuthUser } from "../types/fastify.js";
+import { parseTakenByJson } from "../utils/scheduler-utils.js";
 
 // Share token validity: 1 year in milliseconds
 const SHARE_TOKEN_VALIDITY_MS = 365 * 24 * 60 * 60 * 1000;
@@ -35,17 +36,6 @@ async function getUserId(request: FastifyRequest, reply: FastifyReply): Promise<
 	return authUser.id;
 }
 
-// Helper to parse takenByJson
-function parseTakenByJson(takenByJson: string | null | undefined): string[] {
-	if (!takenByJson) return [];
-	try {
-		const parsed = JSON.parse(takenByJson);
-		return Array.isArray(parsed) ? parsed.filter((s: unknown) => typeof s === "string" && s.trim()) : [];
-	} catch {
-		return [];
-	}
-}
-
 // =============================================================================
 // Share Routes
 // =============================================================================

backend/src/services/intake-reminder-scheduler.ts

@@ -42,10 +42,6 @@ function saveIntakeReminderState(state: IntakeReminderState): void {
 	writeFileSync(intakeReminderStateFile, JSON.stringify(state, null, 2));
 }
 
-function parseBlistersFromRow(row: { usageJson: string; everyJson: string; startJson: string }): Blister[] {
-	return parseBlisters(row);
-}
-
 async function sendIntakeReminderEmail(
 	email: string,
 	intakes: UpcomingIntake[],
@@ -295,7 +291,7 @@ async function checkAndSendIntakeRemindersForUser(
 
 	// Find intakes: upcoming ones in reminder window + past ones for repeat reminders
 	for (const med of medsWithReminders) {
-		const blisters = parseBlistersFromRow(med);
+		const blisters = parseBlisters(med);
 		const takenByArray = parseTakenByJson(med.takenByJson);
 
 		logger.info(