diff --git a/apps/api/src/routes/appointments.ts b/apps/api/src/routes/appointments.ts
index 24d6b3c..2c893b7 100644
--- a/apps/api/src/routes/appointments.ts
+++ b/apps/api/src/routes/appointments.ts
@@ -41,6 +41,10 @@ const createAppointmentSchema = z.object({
       frequencyWeeks: z.number().int().min(1).max(52),
       count: z.number().int().min(2).max(52),
     })
+    .refine(
+      (r) => r.frequencyWeeks * r.count <= 52,
+      { message: "Recurrence series must not exceed 1 year" }
+    )
     .optional(),
 });
 
diff --git a/apps/api/src/routes/book.ts b/apps/api/src/routes/book.ts
index d82823f..f74405c 100644
--- a/apps/api/src/routes/book.ts
+++ b/apps/api/src/routes/book.ts
@@ -102,7 +102,10 @@ bookRouter.get("/availability", async (c) => {
 
 const bookingSchema = z.object({
   serviceId: z.string().uuid(),
-  startTime: z.string().datetime(),
+  startTime: z.string().datetime().refine(
+    (dt) => new Date(dt) > new Date(),
+    { message: "Appointment must be in the future" }
+  ),
   clientName: z.string().min(1).max(200),
   clientEmail: z.string().email(),
   clientPhone: z.string().max(50).optional(),
diff --git a/apps/api/src/routes/invoices.ts b/apps/api/src/routes/invoices.ts
index 96c3e0e..0f65a34 100644
--- a/apps/api/src/routes/invoices.ts
+++ b/apps/api/src/routes/invoices.ts
@@ -44,53 +44,61 @@ const updateInvoiceSchema = z.object({
 });
 
 // List invoices
-invoicesRouter.get("/", async (c) => {
-  const db = getDb();
-  const clientId = c.req.query("clientId");
-  const appointmentId = c.req.query("appointmentId");
-  const status = c.req.query("status");
-  const limit = Math.min(parseInt(c.req.query("limit") || "50", 10), 200);
-  const offset = parseInt(c.req.query("offset") || "0", 10);
-
-  const conditions = [];
-  if (clientId) conditions.push(eq(invoices.clientId, clientId));
-  if (appointmentId) conditions.push(eq(invoices.appointmentId, appointmentId));
-  if (status) conditions.push(eq(invoices.status, status as "draft" | "pending" | "paid" | "void"));
-
-  const whereClause = conditions.length > 0 ? and(...conditions) : undefined;
-
-  const [totalResult] = await db
-    .select({ count: sql<number>`count(*)` })
-    .from(invoices)
-    .where(whereClause);
-
-  const rows = await db
-    .select({
-      id: invoices.id,
-      appointmentId: invoices.appointmentId,
-      clientId: invoices.clientId,
-      clientName: clients.name,
-      subtotalCents: invoices.subtotalCents,
-      taxCents: invoices.taxCents,
-      tipCents: invoices.tipCents,
-      totalCents: invoices.totalCents,
-      status: invoices.status,
-      paymentMethod: invoices.paymentMethod,
-      paidAt: invoices.paidAt,
-      notes: invoices.notes,
-      createdAt: invoices.createdAt,
-      updatedAt: invoices.updatedAt,
-    })
-    .from(invoices)
-    .leftJoin(clients, eq(invoices.clientId, clients.id))
-    .where(whereClause)
-    .orderBy(invoices.createdAt)
-    .limit(limit)
-    .offset(offset);
-
-  return c.json({ data: rows, total: totalResult?.count ?? 0 });
+const listInvoicesQuerySchema = z.object({
+  clientId: z.string().uuid().optional(),
+  appointmentId: z.string().uuid().optional(),
+  status: z.enum(["draft", "pending", "paid", "void"]).optional(),
+  limit: z.coerce.number().int().min(1).max(200).default(50),
+  offset: z.coerce.number().int().min(0).default(0),
 });
 
+invoicesRouter.get(
+  "/",
+  zValidator("query", listInvoicesQuerySchema),
+  async (c) => {
+    const db = getDb();
+    const { clientId, appointmentId, status, limit, offset } = c.req.valid("query");
+
+    const conditions = [];
+    if (clientId) conditions.push(eq(invoices.clientId, clientId));
+    if (appointmentId) conditions.push(eq(invoices.appointmentId, appointmentId));
+    if (status) conditions.push(eq(invoices.status, status as "draft" | "pending" | "paid" | "void"));
+
+    const whereClause = conditions.length > 0 ? and(...conditions) : undefined;
+
+    const [totalResult] = await db
+      .select({ count: sql<number>`count(*)` })
+      .from(invoices)
+      .where(whereClause);
+
+    const rows = await db
+      .select({
+        id: invoices.id,
+        appointmentId: invoices.appointmentId,
+        clientId: invoices.clientId,
+        clientName: clients.name,
+        subtotalCents: invoices.subtotalCents,
+        taxCents: invoices.taxCents,
+        tipCents: invoices.tipCents,
+        totalCents: invoices.totalCents,
+        status: invoices.status,
+        paymentMethod: invoices.paymentMethod,
+        paidAt: invoices.paidAt,
+        notes: invoices.notes,
+        createdAt: invoices.createdAt,
+        updatedAt: invoices.updatedAt,
+      })
+      .from(invoices)
+      .leftJoin(clients, eq(invoices.clientId, clients.id))
+      .where(whereClause)
+      .orderBy(invoices.createdAt)
+      .limit(limit)
+      .offset(offset);
+
+    return c.json({ data: rows, total: totalResult?.count ?? 0 });
+  }
+);
+
 // Get single invoice with line items and tip splits
 invoicesRouter.get("/:id", async (c) => {
   const db = getDb();
diff --git a/apps/api/src/routes/services.ts b/apps/api/src/routes/services.ts
index e9ccc44..659dee2 100644
--- a/apps/api/src/routes/services.ts
+++ b/apps/api/src/routes/services.ts
@@ -9,7 +9,7 @@ const createServiceSchema = z.object({
   name: z.string().min(1).max(200),
   description: z.string().max(2000).optional(),
   basePriceCents: z.number().int().positive(),
-  durationMinutes: z.number().int().positive(),
+  durationMinutes: z.number().int().positive().max(480),
   active: z.boolean().default(true),
 });
 
diff --git a/apps/api/src/routes/stripe-webhooks.ts b/apps/api/src/routes/stripe-webhooks.ts
index 4a948a1..fa7c8ef 100644
--- a/apps/api/src/routes/stripe-webhooks.ts
+++ b/apps/api/src/routes/stripe-webhooks.ts
@@ -1,5 +1,6 @@
 import { Hono } from "hono";
 import Stripe from "stripe";
+import { z } from "zod/v3";
 import { eq, getDb, invoices } from "@groombook/db";
 import { getStripeClient } from "../services/payment.js";
 
@@ -44,10 +45,13 @@ webhooksRouter.post("/stripe", async (c) => {
       const invoiceIds = pi.metadata.groombook_invoice_ids.split(",");
       for (const invoiceId of invoiceIds) {
         if (!invoiceId) continue;
+        const parsed = z.string().uuid().safeParse(invoiceId.trim());
+        if (!parsed.success) continue;
+        const invoiceIdTrimmed = invoiceId.trim();
         const [inv] = await db
           .select()
           .from(invoices)
-          .where(eq(invoices.id, invoiceId))
+          .where(eq(invoices.id, invoiceIdTrimmed))
           .limit(1);
         if (!inv) continue;
         if (inv.stripePaymentIntentId && inv.stripePaymentIntentId !== pi.id) continue;
@@ -60,7 +64,7 @@ webhooksRouter.post("/stripe", async (c) => {
             stripePaymentIntentId: pi.id,
             updatedAt: new Date(),
           })
-          .where(eq(invoices.id, invoiceId));
+          .where(eq(invoices.id, invoiceIdTrimmed));
       }
     }
   } else if (event.type === "payment_intent.payment_failed") {
@@ -69,13 +73,16 @@ webhooksRouter.post("/stripe", async (c) => {
       const invoiceIds = pi.metadata.groombook_invoice_ids.split(",");
       for (const invoiceId of invoiceIds) {
         if (!invoiceId) continue;
+        const parsed = z.string().uuid().safeParse(invoiceId.trim());
+        if (!parsed.success) continue;
+        const invoiceIdTrimmed = invoiceId.trim();
         await db
           .update(invoices)
           .set({
             paymentFailureReason: pi.last_payment_error?.message ?? "Payment failed",
             updatedAt: new Date(),
           })
-          .where(eq(invoices.id, invoiceId));
+          .where(eq(invoices.id, invoiceIdTrimmed));
       }
     }
   } else if (event.type === "charge.refunded") {