diff --git a/apps/api/src/__tests__/clients.test.ts b/apps/api/src/__tests__/clients.test.ts
new file mode 100644
index 0000000..38a2886
--- /dev/null
+++ b/apps/api/src/__tests__/clients.test.ts
@@ -0,0 +1,280 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { Hono } from "hono";
+
+// ─── Mock data ────────────────────────────────────────────────────────────────
+
+const ACTIVE_CLIENT = {
+  id: "client-uuid-1",
+  name: "Alice",
+  email: "alice@example.com",
+  phone: "555-1234",
+  address: "1 Main St",
+  notes: null,
+  status: "active",
+  disabledAt: null,
+  createdAt: new Date(),
+  updatedAt: new Date(),
+};
+
+const DISABLED_CLIENT = {
+  ...ACTIVE_CLIENT,
+  id: "client-uuid-2",
+  name: "Bob",
+  status: "disabled",
+  disabledAt: new Date(),
+};
+
+// ─── Queue-based mock DB ──────────────────────────────────────────────────────
+
+let selectRows: Record<string, unknown>[] = [];
+let insertedValues: Record<string, unknown>[] = [];
+let updatedValues: Record<string, unknown>[] = [];
+let deletedId: string | null = null;
+
+function resetMock() {
+  selectRows = [];
+  insertedValues = [];
+  updatedValues = [];
+  deletedId = null;
+}
+
+vi.mock("@groombook/db", () => {
+  function makeChainable(data: unknown[]): unknown {
+    const arr = [...data];
+    const chain = new Proxy(arr, {
+      get(target, prop) {
+        if (prop === "where" || prop === "orderBy" || prop === "limit") {
+          return () => chain;
+        }
+        // @ts-expect-error proxy
+        return target[prop];
+      },
+    });
+    return chain;
+  }
+
+  const clients = new Proxy(
+    { _name: "clients" },
+    { get: (t, p) => (p === "_name" ? "clients" : { table: "clients", column: p }) }
+  );
+
+  return {
+    getDb: () => ({
+      select: () => ({
+        from: () => makeChainable(selectRows),
+      }),
+      insert: () => ({
+        values: (vals: Record<string, unknown>) => {
+          insertedValues.push(vals);
+          return {
+            returning: () => [{ ...ACTIVE_CLIENT, ...vals, id: "client-uuid-new" }],
+          };
+        },
+      }),
+      update: () => ({
+        set: (vals: Record<string, unknown>) => ({
+          where: () => {
+            updatedValues.push(vals);
+            return {
+              returning: () =>
+                selectRows.length > 0
+                  ? [{ ...selectRows[0], ...vals }]
+                  : [],
+            };
+          },
+        }),
+      }),
+      delete: () => ({
+        where: () => {
+          deletedId = "client-uuid-1";
+          return {
+            returning: () =>
+              selectRows.length > 0 ? [selectRows[0]] : [],
+          };
+        },
+      }),
+    }),
+    clients,
+    eq: vi.fn(),
+    and: vi.fn(),
+  };
+});
+
+// ─── App setup ────────────────────────────────────────────────────────────────
+
+const { clientsRouter } = await import("../routes/clients.js");
+
+const app = new Hono();
+app.route("/clients", clientsRouter);
+
+function jsonRequest(method: string, path: string, body?: unknown) {
+  return app.request(path, {
+    method,
+    headers: { "Content-Type": "application/json" },
+    body: body !== undefined ? JSON.stringify(body) : undefined,
+  });
+}
+
+beforeEach(() => resetMock());
+
+// ─── GET / ────────────────────────────────────────────────────────────────────
+
+describe("GET /clients", () => {
+  it("returns active clients", async () => {
+    selectRows = [ACTIVE_CLIENT];
+    const res = await app.request("/clients");
+    expect(res.status).toBe(200);
+    const body = await res.json();
+    expect(Array.isArray(body)).toBe(true);
+    expect(body).toHaveLength(1);
+  });
+
+  it("returns all clients when includeDisabled=true", async () => {
+    selectRows = [ACTIVE_CLIENT, DISABLED_CLIENT];
+    const res = await app.request("/clients?includeDisabled=true");
+    expect(res.status).toBe(200);
+    const body = await res.json();
+    expect(body).toHaveLength(2);
+  });
+
+  it("returns empty array when no clients exist", async () => {
+    selectRows = [];
+    const res = await app.request("/clients");
+    expect(res.status).toBe(200);
+    const body = await res.json();
+    expect(body).toEqual([]);
+  });
+});
+
+// ─── GET /:id ─────────────────────────────────────────────────────────────────
+
+describe("GET /clients/:id", () => {
+  it("returns a single client", async () => {
+    selectRows = [ACTIVE_CLIENT];
+    const res = await app.request("/clients/client-uuid-1");
+    expect(res.status).toBe(200);
+    const body = await res.json();
+    expect(body.id).toBe("client-uuid-1");
+    expect(body.name).toBe("Alice");
+  });
+
+  it("returns 404 for a nonexistent client", async () => {
+    selectRows = [];
+    const res = await app.request("/clients/nonexistent");
+    expect(res.status).toBe(404);
+    const body = await res.json();
+    expect(body.error).toMatch(/not found/i);
+  });
+});
+
+// ─── POST / ───────────────────────────────────────────────────────────────────
+
+describe("POST /clients", () => {
+  it("creates a client with valid data", async () => {
+    const res = await jsonRequest("POST", "/clients", {
+      name: "Charlie",
+      email: "charlie@example.com",
+    });
+    expect(res.status).toBe(201);
+    const body = await res.json();
+    expect(body.name).toBe("Charlie");
+    expect(insertedValues).toHaveLength(1);
+    expect(insertedValues[0]!.name).toBe("Charlie");
+  });
+
+  it("creates a client with only required name field", async () => {
+    const res = await jsonRequest("POST", "/clients", { name: "Dana" });
+    expect(res.status).toBe(201);
+    expect(insertedValues[0]!.name).toBe("Dana");
+  });
+
+  it("rejects empty name", async () => {
+    const res = await jsonRequest("POST", "/clients", { name: "" });
+    expect(res.status).toBe(400);
+  });
+
+  it("rejects invalid email format", async () => {
+    const res = await jsonRequest("POST", "/clients", {
+      name: "Eve",
+      email: "not-an-email",
+    });
+    expect(res.status).toBe(400);
+  });
+
+  it("rejects missing body", async () => {
+    const res = await app.request("/clients", { method: "POST" });
+    expect(res.status).toBe(400);
+  });
+});
+
+// ─── PATCH /:id ───────────────────────────────────────────────────────────────
+
+describe("PATCH /clients/:id", () => {
+  it("updates client fields", async () => {
+    selectRows = [ACTIVE_CLIENT];
+    const res = await jsonRequest("PATCH", "/clients/client-uuid-1", {
+      name: "Alice Updated",
+    });
+    expect(res.status).toBe(200);
+    const body = await res.json();
+    expect(body.name).toBe("Alice Updated");
+    expect(updatedValues[0]!.name).toBe("Alice Updated");
+  });
+
+  it("sets disabledAt when status is set to disabled", async () => {
+    selectRows = [ACTIVE_CLIENT];
+    await jsonRequest("PATCH", "/clients/client-uuid-1", {
+      status: "disabled",
+    });
+    expect(updatedValues[0]!.status).toBe("disabled");
+    expect(updatedValues[0]!.disabledAt).toBeDefined();
+  });
+
+  it("clears disabledAt when re-enabling", async () => {
+    selectRows = [DISABLED_CLIENT];
+    await jsonRequest("PATCH", "/clients/client-uuid-2", {
+      status: "active",
+    });
+    expect(updatedValues[0]!.disabledAt).toBeNull();
+  });
+
+  it("returns 404 when client not found", async () => {
+    selectRows = [];
+    const res = await jsonRequest("PATCH", "/clients/nonexistent", {
+      name: "Ghost",
+    });
+    expect(res.status).toBe(404);
+  });
+});
+
+// ─── DELETE /:id ──────────────────────────────────────────────────────────────
+
+describe("DELETE /clients/:id", () => {
+  it("requires ?confirm=true", async () => {
+    const res = await app.request("/clients/client-uuid-1", {
+      method: "DELETE",
+    });
+    expect(res.status).toBe(400);
+    const body = await res.json();
+    expect(body.error).toMatch(/confirm/i);
+  });
+
+  it("deletes a client with ?confirm=true", async () => {
+    selectRows = [ACTIVE_CLIENT];
+    const res = await app.request("/clients/client-uuid-1?confirm=true", {
+      method: "DELETE",
+    });
+    expect(res.status).toBe(200);
+    const body = await res.json();
+    expect(body.ok).toBe(true);
+    expect(deletedId).toBe("client-uuid-1");
+  });
+
+  it("returns 404 when client not found", async () => {
+    selectRows = [];
+    const res = await app.request("/clients/nonexistent?confirm=true", {
+      method: "DELETE",
+    });
+    expect(res.status).toBe(404);
+  });
+});
diff --git a/apps/api/src/__tests__/email.test.ts b/apps/api/src/__tests__/email.test.ts
new file mode 100644
index 0000000..6ff56de
--- /dev/null
+++ b/apps/api/src/__tests__/email.test.ts
@@ -0,0 +1,106 @@
+import { describe, it, expect } from "vitest";
+import {
+  buildConfirmationEmail,
+  buildReminderEmail,
+} from "../services/email.js";
+
+const START = new Date("2026-03-25T15:00:00Z");
+
+const BASE = {
+  clientName: "Jane Doe",
+  petName: "Biscuit",
+  serviceName: "Full Groom",
+  groomerName: "Alex",
+  startTime: START,
+};
+
+describe("buildConfirmationEmail", () => {
+  it("addresses the correct recipient", () => {
+    const mail = buildConfirmationEmail("jane@example.com", BASE);
+    expect(mail.to).toBe("jane@example.com");
+  });
+
+  it("includes the pet name in the subject", () => {
+    const mail = buildConfirmationEmail("jane@example.com", BASE);
+    expect(mail.subject).toContain("Biscuit");
+  });
+
+  it("includes confirmation wording in subject", () => {
+    const mail = buildConfirmationEmail("jane@example.com", BASE);
+    expect(mail.subject).toMatch(/confirmed/i);
+  });
+
+  it("includes client name in the plain text body", () => {
+    const mail = buildConfirmationEmail("jane@example.com", BASE);
+    expect(mail.text).toContain("Jane Doe");
+  });
+
+  it("includes service name in plain text body", () => {
+    const mail = buildConfirmationEmail("jane@example.com", BASE);
+    expect(mail.text).toContain("Full Groom");
+  });
+
+  it("includes groomer name when provided", () => {
+    const mail = buildConfirmationEmail("jane@example.com", BASE);
+    expect(mail.text).toContain("Alex");
+  });
+
+  it("omits groomer when groomerName is null", () => {
+    const mail = buildConfirmationEmail("jane@example.com", {
+      ...BASE,
+      groomerName: null,
+    });
+    expect(mail.text).not.toContain("with ");
+  });
+
+  it("includes HTML body", () => {
+    const mail = buildConfirmationEmail("jane@example.com", BASE);
+    expect(mail.html).toBeTruthy();
+    expect(mail.html).toContain("Biscuit");
+  });
+});
+
+describe("buildReminderEmail", () => {
+  it("addresses the correct recipient", () => {
+    const mail = buildReminderEmail("jane@example.com", BASE, 24);
+    expect(mail.to).toBe("jane@example.com");
+  });
+
+  it("says 'tomorrow' for 24-hour reminder", () => {
+    const mail = buildReminderEmail("jane@example.com", BASE, 24);
+    expect(mail.subject).toContain("tomorrow");
+    expect(mail.text).toContain("tomorrow");
+  });
+
+  it("says 'in X hours' for sub-24-hour reminders", () => {
+    const mail = buildReminderEmail("jane@example.com", BASE, 2);
+    expect(mail.subject).toContain("in 2 hours");
+    expect(mail.text).toContain("in 2 hours");
+  });
+
+  it("includes pet name in subject", () => {
+    const mail = buildReminderEmail("jane@example.com", BASE, 24);
+    expect(mail.subject).toContain("Biscuit");
+  });
+
+  it("includes service name in plain text body", () => {
+    const mail = buildReminderEmail("jane@example.com", BASE, 24);
+    expect(mail.text).toContain("Full Groom");
+  });
+
+  it("includes groomer name when provided", () => {
+    const mail = buildReminderEmail("jane@example.com", BASE, 24);
+    expect(mail.text).toContain("Alex");
+  });
+
+  it("omits groomer when groomerName is null", () => {
+    const mail = buildReminderEmail("jane@example.com", { ...BASE, groomerName: null }, 24);
+    expect(mail.text).not.toContain("with ");
+  });
+
+  it("includes HTML body", () => {
+    const mail = buildReminderEmail("jane@example.com", BASE, 24);
+    expect(mail.html).toBeTruthy();
+    expect(mail.html).toContain("Biscuit");
+  });
+});
diff --git a/apps/web/src/__tests__/ImpersonationBanner.test.tsx b/apps/web/src/__tests__/ImpersonationBanner.test.tsx
new file mode 100644
index 0000000..4dca0d6
--- /dev/null
+++ b/apps/web/src/__tests__/ImpersonationBanner.test.tsx
@@ -0,0 +1,135 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { render, screen, fireEvent, act } from "@testing-library/react";
+import { ImpersonationBanner } from "../portal/ImpersonationBanner.js";
+import type { ImpersonationSession } from "@groombook/types";
+
+function makeSession(overrides: Partial<ImpersonationSession> = {}): ImpersonationSession {
+  const now = new Date();
+  const expires = new Date(now.getTime() + 30 * 60 * 1000); // 30 min from now
+  return {
+    id: "session-uuid-1",
+    staffId: "staff-uuid-1",
+    clientId: "client-uuid-1",
+    reason: "Customer requested help",
+    status: "active",
+    startedAt: now.toISOString(),
+    endedAt: null,
+    expiresAt: expires.toISOString(),
+    createdAt: now.toISOString(),
+    ...overrides,
+  };
+}
+
+describe("ImpersonationBanner", () => {
+  const onEnd = vi.fn();
+  const onExtend = vi.fn();
+  const onShowAudit = vi.fn();
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+    vi.useFakeTimers();
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it("renders banner when session is active", () => {
+    render(
+      <ImpersonationBanner
+        session={makeSession()}
+        isExtended={false}
+        onEnd={onEnd}
+        onExtend={onExtend}
+        onShowAudit={onShowAudit}
+      />
+    );
+    expect(screen.getByText(/STAFF VIEW/)).toBeInTheDocument();
+  });
+
+  it("calls onEnd when End Session is clicked", () => {
+    render(
+      <ImpersonationBanner
+        session={makeSession()}
+        isExtended={false}
+        onEnd={onEnd}
+        onExtend={onExtend}
+        onShowAudit={onShowAudit}
+      />
+    );
+    fireEvent.click(screen.getByRole("button", { name: /end session/i }));
+    expect(onEnd).toHaveBeenCalledTimes(1);
+  });
+
+  it("calls onShowAudit when Audit is clicked", () => {
+    render(
+      <ImpersonationBanner
+        session={makeSession()}
+        isExtended={false}
+        onEnd={onEnd}
+        onExtend={onExtend}
+        onShowAudit={onShowAudit}
+      />
+    );
+    fireEvent.click(screen.getByRole("button", { name: /audit/i }));
+    expect(onShowAudit).toHaveBeenCalledTimes(1);
+  });
+
+  it("calls onEnd automatically when session expires", async () => {
+    const expiredSoon = new Date(Date.now() + 500);
+    const session = makeSession({ expiresAt: expiredSoon.toISOString() });
+
+    render(
+      <ImpersonationBanner
+        session={session}
+        isExtended={false}
+        onEnd={onEnd}
+        onExtend={onExtend}
+        onShowAudit={onShowAudit}
+      />
+    );
+
+    // Advance past expiry
+    await act(async () => {
+      vi.advanceTimersByTime(2000);
+    });
+
+    expect(onEnd).toHaveBeenCalled();
+  });
+
+  it("shows Extend button when warning is active and session not yet extended", () => {
+    // Set expiry to 3 min from now — within warning threshold (< 5 min)
+    const expiresAt = new Date(Date.now() + 3 * 60 * 1000).toISOString();
+    render(
+      <ImpersonationBanner
+        session={makeSession({ expiresAt })}
+        isExtended={false}
+        onEnd={onEnd}
+        onExtend={onExtend}
+        onShowAudit={onShowAudit}
+      />
+    );
+    // Tick the timer once to trigger showWarning
+    act(() => {
+      vi.advanceTimersByTime(1000);
+    });
+    expect(screen.getByRole("button", { name: /extend/i })).toBeInTheDocument();
+  });
+
+  it("does not show Extend button when already extended", () => {
+    const expiresAt = new Date(Date.now() + 3 * 60 * 1000).toISOString();
+    render(
+      <ImpersonationBanner
+        session={makeSession({ expiresAt })}
+        isExtended={true}
+        onEnd={onEnd}
+        onExtend={onExtend}
+        onShowAudit={onShowAudit}
+      />
+    );
+    act(() => {
+      vi.advanceTimersByTime(1000);
+    });
+    expect(screen.queryByRole("button", { name: /extend/i })).not.toBeInTheDocument();
+  });
+});