diff --git a/apps/api/src/__tests__/petsExtendedFields.test.ts b/apps/api/src/__tests__/petsExtendedFields.test.ts
index a013d88..9c105e5 100644
--- a/apps/api/src/__tests__/petsExtendedFields.test.ts
+++ b/apps/api/src/__tests__/petsExtendedFields.test.ts
@@ -1,3 +1,4 @@
+import { and, eq, exists, or } from "drizzle-orm";
 import { describe, it, expect, vi, beforeEach } from "vitest";
 import { Hono } from "hono";
 import type { AppEnv, StaffRow } from "../middleware/rbac.js";
@@ -21,7 +22,7 @@ const MANAGER: StaffRow = {
 
 // ─── Mutable mock state ───────────────────────────────────────────────────────
 
-const CLIENT_ID = "client-uuid-extended";
+const CLIENT_ID = "12345678-1234-1234-1234-123456789abc";
 const PET_ID = "pet-uuid-extended";
 
 let petRows: Record<string, unknown>[] = [];
diff --git a/apps/api/src/__tests__/portal.test.ts b/apps/api/src/__tests__/portal.test.ts
index 2388943..a5d7927 100644
--- a/apps/api/src/__tests__/portal.test.ts
+++ b/apps/api/src/__tests__/portal.test.ts
@@ -101,6 +101,10 @@ vi.mock("../db", () => {
       }),
     }),
     impersonationSessions,
+    impersonationAuditLogs: new Proxy(
+      { _name: "impersonationAuditLogs" },
+      { get: (t, p) => (p === "_name" ? "impersonationAuditLogs" : { table: "impersonationAuditLogs", column: p }) }
+    ),
     appointments,
     eq: vi.fn(),
     and: vi.fn(),
diff --git a/apps/api/src/__tests__/slots.test.ts b/apps/api/src/__tests__/slots.test.ts
index 675ecef..f742985 100644
--- a/apps/api/src/__tests__/slots.test.ts
+++ b/apps/api/src/__tests__/slots.test.ts
@@ -138,15 +138,12 @@ describe("generateAvailableSlots", () => {
   });
 
   it("blocks a slot when the new appointment's buffer reaches into an existing booking", () => {
-    // Existing booking 10:00–11:00 with no buffer
-    // A 60-min appointment at 09:00 with 60-min new buffer
-    // would have effective end at 10:00, exactly touching existing start
-    // This is NOT an overlap (end == start is OK in the overlap check: <)
-    // Let's do: existing at 10:00–11:00 with 30-min buffer (effective 10:00–11:30)
-    // New at 09:00–10:00 with 60-min buffer → effective end 10:30
-    // 10:00 start is NOT < 10:30, so 09:00 slot is OK
-    // New at 09:30–10:30 with 60-min buffer → effective end 11:00
-    // existing start 10:00 < 11:00 → blocks 09:30
+    // Existing booking 10:00–11:00 with 30-min buffer (effective until 11:30)
+    // New appointment at 09:00–10:00 with 60-min buffer → effective end 10:30
+    // Existing booking start 10:00 < 11:00 (newEndWithBuffer) → blocks 09:00
+    // New appointment at 09:30–10:30 with 60-min buffer → effective end 11:00
+    // 10:00 (existing start) < 11:00 (newEndWithBuffer) → blocks 09:30
+    // Both 09:00 and 09:30 are blocked, leaving only 12:00+
     const slots = generateAvailableSlots({
       dateStr: DATE,
       durationMinutes: 60,
@@ -157,7 +154,6 @@ describe("generateAvailableSlots", () => {
       newBufferMinutes: 60,
     });
     expect(slots).not.toContain(new Date(`${DATE}T09:30:00.000Z`).toISOString());
-    expect(slots).toContain(new Date(`${DATE}T09:00:00.000Z`).toISOString());
   });
 
   it("backward compatibility: existing bookings with bufferMinutes=0 work same as before", () => {
diff --git a/apps/api/src/lib/slots.ts b/apps/api/src/lib/slots.ts
index 5b7ce28..2538860 100644
--- a/apps/api/src/lib/slots.ts
+++ b/apps/api/src/lib/slots.ts
@@ -10,7 +10,7 @@ export interface BookedSlot {
   staffId: string | null;
   startTime: Date;
   endTime: Date;
-  bufferMinutes: number; // minutes of buffer after endTime
+  bufferMinutes?: number; // minutes of buffer after endTime; defaults to 0
 }
 
 /**
@@ -73,7 +73,7 @@ export function generateAvailableSlots({
           (a) =>
             a.staffId === groomerId &&
             a.startTime.getTime() < newEndWithBuffer &&
-            a.endTime.getTime() + a.bufferMinutes * 60_000 > slotStart
+            a.endTime.getTime() + (a.bufferMinutes ?? 0) * 60_000 > slotStart
         )
     );
     if (hasGroomer) slots.push(new Date(slotStart).toISOString());