fix: correct dose ID generation for empty takenBy arrays (#105)

The takenBy field is a string[]. Empty arrays [] are truthy in JavaScript,
causing d.takenBy ? [...] patterns to generate dose IDs with trailing
hyphens (e.g., '5-0-173...-') instead of base IDs ('5-0-173...').

This mismatch between ID generation and computeMissedPastDoseIds (which
correctly uses .length > 0) caused doses to always appear as missed.

Changes:
- Add expandDoseIds() helper function using correct .length > 0 check
- Replace 8 buggy inline patterns in DashboardPage.tsx
- Refactor SchedulePage.tsx to use shared expandDoseIds()
- Add backend startup repair to strip trailing hyphens from existing IDs
- Add 12 new tests (6 frontend + 6 backend)

backend/src/db/client.ts

@@ -165,6 +165,29 @@ export async function ensureDefaultUser(client: Client, authEnabled: boolean): P
 
 const MS_PER_DAY = 86_400_000;
 
+/**
+ * Repair dose IDs that have a trailing hyphen caused by a frontend bug where
+ * `[].toString()` produced an empty string, resulting in IDs like "5-0-1729123200000-"
+ * instead of "5-0-1729123200000". This strips trailing hyphens from all dose IDs.
+ *
+ * This function is idempotent - safe to run on every startup.
+ */
+export async function repairTrailingHyphenDoseIds(client: Client): Promise<{ repaired: number; errors: string[] }> {
+	const errors: string[] = [];
+	let repaired = 0;
+
+	try {
+		const result = await client.execute(
+			"UPDATE dose_tracking SET dose_id = RTRIM(dose_id, '-') WHERE dose_id LIKE '%-'"
+		);
+		repaired = result.rowsAffected;
+	} catch (e: any) {
+		errors.push(`Trailing-hyphen repair failed: ${e.message}`);
+	}
+
+	return { repaired, errors };
+}
+
 /**
  * Repair orphaned dose tracking IDs that no longer match the current intake schedule.
  * This fixes dose IDs that became invalid when a medication's schedule was changed
@@ -355,6 +378,15 @@ async function runMigrations() {
 	}
 	console.log(`[DB] Tables verified/created`);
 
+	// Repair dose IDs with trailing hyphens (from frontend takenBy bug)
+	const trailingResult = await repairTrailingHyphenDoseIds(client);
+	if (trailingResult.repaired > 0) {
+		console.log(`[DB] Repaired ${trailingResult.repaired} dose IDs with trailing hyphens`);
+	}
+	if (trailingResult.errors.length > 0) {
+		trailingResult.errors.forEach((err) => console.error(`[DB] Trailing-hyphen repair error:`, err));
+	}
+
 	// Repair orphaned dose tracking IDs from past schedule changes
 	const repairResult = await repairOrphanedDoseIds(client);
 	if (repairResult.repaired > 0) {