diff --git a/src/core/parentClient_test.ts b/src/core/parentClient_test.ts
index 3c828e8..e3a07e6 100644
--- a/src/core/parentClient_test.ts
+++ b/src/core/parentClient_test.ts
@@ -1,35 +1,191 @@
-import { assertRejects } from "@std/assert";
-import { ParentClient } from "../core/parentClient.ts";
-
-Deno.test("Throws when no email is provided", async () => {
-	const client = new ParentClient("", "password");
-	await assertRejects(
-		async () => {
-			await client.login();
-		},
-		Error,
-		"Email not provided",
-	);
-});
-
-Deno.test("Throws when no password is provided", async () => {
-	const client = new ParentClient("email", "");
-	await assertRejects(
-		async () => {
-			await client.login();
-		},
-		Error,
-		"Password not provided",
-	);
-});
-
-Deno.test("Throws with invalid username and password", async () => {
-	const client = new ParentClient("invalid", "invalid");
-	await assertRejects(
-		async () => {
-			await client.login();
-		},
-		Error,
-		"Unauthenticated: ClassCharts didn't return authentication cookies",
-	);
-});
+import { BaseClient } from "./baseClient.js";
+import { API_BASE_PARENT, BASE_URL } from "../utils/consts.js";
+import { parseCookies } from "../utils/utils.js";
+import type { ChangePasswordResponse, GetPupilsResponse } from "../types.js";
+
+/**
+ * Parent Client.
+ * See {@link BaseClient} for all shared methods.
+ *
+ * @example
+ * ```ts
+ * import { ParentClient } from "classcharts-api";
+ * const client = new ParentClient("username", "password");
+ * await client.login();
+ * ```
+ */
+export class ParentClient extends BaseClient {
+  private password = "";
+  private email = "";
+  public pupils: GetPupilsResponse = [];
+
+  /**
+   * @param email Parent's email address
+   * @param password Parent's password
+   */
+  constructor(email: string, password: string) {
+    super(API_BASE_PARENT);
+    this.email = String(email);
+    this.password = String(password);
+    this.pupils = [];
+  }
+
+  /**
+   * Authenticates with ClassCharts.
+   *
+   * Handles the TES SSO verification step introduced in April 2026.
+   * Without the handshake, getPupils() would trigger an infinite redirect loop
+   * between classcharts.com and session.tes.com, causing a
+   * "redirect count exceeded" error.
+   */
+  async login(): Promise<void> {
+    if (!this.email) {
+      throw new Error("Email not provided");
+    }
+    if (!this.password) {
+      throw new Error("Password not provided");
+    }
+
+    const formData = new URLSearchParams();
+    formData.append("_method", "POST");
+    formData.append("email", this.email);
+    formData.append("logintype", "existing");
+    formData.append("password", this.password);
+    formData.append("recaptcha-token", "no-token-available");
+
+    const headers = new Headers({
+      "Content-Type": "application/x-www-form-urlencoded",
+    });
+
+    const response = await fetch(`${BASE_URL}/parent/login`, {
+      method: "POST",
+      body: formData,
+      headers: headers,
+      redirect: "manual",
+    });
+
+    if (response.status !== 302 || !response.headers.has("set-cookie")) {
+      await response.body?.cancel();
+      throw new Error(
+        "Unauthenticated: ClassCharts didn't return authentication cookies"
+      );
+    }
+
+    const cookies = String(response.headers.get("set-cookie"));
+    const sessionCookies = parseCookies(cookies);
+    const sessionID = JSON.parse(
+      String(sessionCookies.parent_session_credentials)
+    );
+    this.sessionId = sessionID.session_id;
+
+    // Perform the TES SSO handshake before calling getPupils(), otherwise the
+    // /apiv2parent/pupils endpoint redirects to session.tes.com/v1/verify and
+    // back in an infinite loop (introduced ~27 April 2026).
+    await this.performTesSsoHandshake(sessionCookies);
+
+    this.pupils = await this.getPupils();
+    if (!this.pupils) {
+      throw new Error("Account has no pupils attached");
+    }
+    this.studentId = this.pupils[0].id;
+  }
+
+  /**
+   * Satisfies the TES SSO verification handshake introduced in April 2026.
+   *
+   * ClassCharts now redirects the first authenticated request to
+   * `session.tes.com/v1/verify`, which redirects straight back, creating a
+   * loop. Following the two-hop chain once (with `redirect: "manual"`) sets
+   * the necessary TES cookies and allows subsequent API calls to succeed.
+   *
+   * @param sessionCookies Parsed session cookies from the login POST response
+   */
+  private async performTesSsoHandshake(
+    sessionCookies: Record<string, string>
+  ): Promise<void> {
+    const ccSession = sessionCookies["cc-session"];
+    const parentCreds = sessionCookies["parent_session_credentials"];
+
+    if (!ccSession || !parentCreds) {
+      // Cookies absent — skip handshake gracefully (guards against future
+      // auth flow changes where these cookie names may differ).
+      return;
+    }
+
+    const cookieHeader = `cc-session=${ccSession}; parent_session_credentials=${parentCreds}`;
+
+    const verifyUrl =
+      "https://session.tes.com/v1/verify?returnUrl=" +
+      encodeURIComponent(`${BASE_URL}/apiv2parent/pupils`);
+
+    // Hop 1: classcharts.com → session.tes.com/v1/verify
+    const tesRes = await fetch(verifyUrl, {
+      headers: { Cookie: cookieHeader },
+      redirect: "manual",
+    });
+
+    // Hop 2: session.tes.com → classcharts.com (back-redirect completing the handshake)
+    const tesLocation = tesRes.headers.get("location");
+    if (tesLocation) {
+      await fetch(tesLocation, {
+        headers: { Cookie: cookieHeader },
+        redirect: "manual",
+      });
+    }
+  }
+
+  /**
+   * Get a list of pupils connected to this parent's account
+   * @returns an array of Pupils connected to this parent's account
+   */
+  async getPupils(): Promise<GetPupilsResponse> {
+    const response = await this.makeAuthedRequest(`${this.API_BASE}/pupils`, {
+      method: "GET",
+    });
+    return response.data;
+  }
+
+  /**
+   * Selects a pupil to be used with API requests
+   * @param pupilId Pupil ID obtained from this.pupils or getPupils()
+   *
+   * @see getPupils
+   */
+  selectPupil(pupilId: number): void {
+    if (!pupilId) {
+      throw new Error("No pupil ID specified");
+    }
+    const pupils = this.pupils;
+    for (let i = 0; i < pupils.length; i++) {
+      const pupil = pupils[i];
+      if (pupil.id === pupilId) {
+        this.studentId = pupil.id;
+        return;
+      }
+    }
+    throw new Error("No pupil with specified ID returned");
+  }
+
+  /**
+   * Changes the login password for the current parent account
+   * @param currentPassword Current password
+   * @param newPassword New password
+   * @returns Whether the request was successful
+   */
+  async changePassword(
+    currentPassword: string,
+    newPassword: string
+  ): Promise<ChangePasswordResponse> {
+    const formData = new URLSearchParams();
+    formData.append("current", currentPassword);
+    formData.append("new", newPassword);
+    formData.append("repeat", newPassword);
+    return await this.makeAuthedRequest(`${this.API_BASE}/password`, {
+      method: "POST",
+      body: formData,
+      headers: {
+        "Content-Type": "application/x-www-form-urlencoded",
+      },
+    });
+  }
+}