diff --git a/packages/frontend/__tests__/api/groupInviteRoute.test.ts b/packages/frontend/__tests__/api/groupInviteRoute.test.ts
new file mode 100644
index 000000000..0548cb727
--- /dev/null
+++ b/packages/frontend/__tests__/api/groupInviteRoute.test.ts
@@ -0,0 +1,184 @@
+import { beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
+
+const mockState = vi.hoisted(() => {
+  const getSessionFromRequest = vi.fn();
+  const getGroupBySlug = vi.fn();
+  const getGroupMembership = vi.fn();
+  const createGroupInvite = vi.fn();
+  const revalidateGroupCaches = vi.fn();
+
+  return {
+    getSessionFromRequest,
+    getGroupBySlug,
+    getGroupMembership,
+    createGroupInvite,
+    revalidateGroupCaches,
+    reset() {
+      getSessionFromRequest.mockReset();
+      getGroupBySlug.mockReset();
+      getGroupMembership.mockReset();
+      createGroupInvite.mockReset();
+      revalidateGroupCaches.mockReset();
+    },
+  };
+});
+
+vi.mock("@/lib/auth/requestSession", () => ({
+  getSessionFromRequest: mockState.getSessionFromRequest,
+}));
+
+vi.mock("@/lib/groups/cache", () => ({
+  revalidateGroupCaches: mockState.revalidateGroupCaches,
+}));
+
+vi.mock("@/lib/groups/invites", () => {
+  class GroupInviteError extends Error {
+    constructor(
+      public readonly code: "not_found" | "forbidden" | "invalid",
+      message: string
+    ) {
+      super(message);
+    }
+  }
+
+  return {
+    createGroupInvite: mockState.createGroupInvite,
+    GroupInviteError,
+  };
+});
+
+vi.mock("@/lib/groups/permissions", () => ({
+  getGroupMembership: mockState.getGroupMembership,
+}));
+
+vi.mock("@/lib/groups/queries", () => ({
+  getGroupBySlug: mockState.getGroupBySlug,
+}));
+
+vi.mock("../../src/lib/db/schema", () => ({
+  groupRoles: ["owner", "admin", "member"],
+}));
+
+type ModuleExports = typeof import("../../src/app/api/groups/[slug]/invite/route");
+
+let POST: ModuleExports["POST"];
+
+beforeAll(async () => {
+  const routeModule = await import("../../src/app/api/groups/[slug]/invite/route");
+  POST = routeModule.POST;
+});
+
+beforeEach(() => {
+  mockState.reset();
+  mockState.getSessionFromRequest.mockResolvedValue({
+    id: "actor-1",
+    username: "actor",
+    displayName: null,
+    avatarUrl: null,
+  });
+  mockState.getGroupBySlug.mockResolvedValue({
+    id: "group-1",
+    slug: "team",
+    name: "Team",
+    isPublic: false,
+  });
+  mockState.createGroupInvite.mockResolvedValue({
+    id: "invite-1",
+    token: "tg_token",
+    role: "member",
+    invitedUsername: null,
+    expiresAt: new Date("2026-06-01T00:00:00Z"),
+  });
+});
+
+function requestWithRole(role: string) {
+  return new Request("http://localhost:3000/api/groups/team/invite", {
+    method: "POST",
+    body: JSON.stringify({ role }),
+  });
+}
+
+describe("POST /api/groups/[slug]/invite", () => {
+  it("forbids admins from creating admin invites", async () => {
+    mockState.getGroupMembership.mockResolvedValue({ role: "admin" });
+
+    const response = await POST(requestWithRole("admin"), {
+      params: Promise.resolve({ slug: "team" }),
+    });
+
+    expect(response.status).toBe(403);
+    expect(await response.json()).toEqual({ error: "Forbidden" });
+    expect(mockState.createGroupInvite).not.toHaveBeenCalled();
+    expect(mockState.revalidateGroupCaches).not.toHaveBeenCalled();
+  });
+
+  it("forbids owner invites", async () => {
+    mockState.getGroupMembership.mockResolvedValue({ role: "owner" });
+
+    const response = await POST(requestWithRole("owner"), {
+      params: Promise.resolve({ slug: "team" }),
+    });
+
+    expect(response.status).toBe(403);
+    expect(await response.json()).toEqual({ error: "Forbidden" });
+    expect(mockState.createGroupInvite).not.toHaveBeenCalled();
+    expect(mockState.revalidateGroupCaches).not.toHaveBeenCalled();
+  });
+
+  it("allows owners to create admin invites", async () => {
+    mockState.getGroupMembership.mockResolvedValue({ role: "owner" });
+    mockState.createGroupInvite.mockResolvedValue({
+      id: "invite-1",
+      token: "tg_token",
+      role: "admin",
+      invitedUsername: null,
+      expiresAt: new Date("2026-06-01T00:00:00Z"),
+    });
+
+    const response = await POST(requestWithRole("admin"), {
+      params: Promise.resolve({ slug: "team" }),
+    });
+
+    expect(response.status).toBe(201);
+    expect(mockState.createGroupInvite).toHaveBeenCalledWith({
+      groupId: "group-1",
+      invitedBy: "actor-1",
+      role: "admin",
+      invitedUsername: null,
+    });
+    expect(mockState.revalidateGroupCaches).toHaveBeenCalledWith("group-1", "team");
+  });
+
+  it("allows admins to create member invites", async () => {
+    mockState.getGroupMembership.mockResolvedValue({ role: "admin" });
+
+    const response = await POST(requestWithRole("member"), {
+      params: Promise.resolve({ slug: "team" }),
+    });
+
+    expect(response.status).toBe(201);
+    expect(mockState.createGroupInvite).toHaveBeenCalledWith({
+      groupId: "group-1",
+      invitedBy: "actor-1",
+      role: "member",
+      invitedUsername: null,
+    });
+    expect(mockState.revalidateGroupCaches).toHaveBeenCalledWith("group-1", "team");
+  });
+
+  it("defaults invalid requested roles to member invites", async () => {
+    mockState.getGroupMembership.mockResolvedValue({ role: "admin" });
+
+    const response = await POST(requestWithRole("invalid"), {
+      params: Promise.resolve({ slug: "team" }),
+    });
+
+    expect(response.status).toBe(201);
+    expect(mockState.createGroupInvite).toHaveBeenCalledWith({
+      groupId: "group-1",
+      invitedBy: "actor-1",
+      role: "member",
+      invitedUsername: null,
+    });
+  });
+});
diff --git a/packages/frontend/src/app/api/groups/[slug]/invite/route.ts b/packages/frontend/src/app/api/groups/[slug]/invite/route.ts
index cf3e0e11d..8a378c6a4 100644
--- a/packages/frontend/src/app/api/groups/[slug]/invite/route.ts
+++ b/packages/frontend/src/app/api/groups/[slug]/invite/route.ts
@@ -4,7 +4,7 @@ import { revalidateGroupCaches } from "@/lib/groups/cache";
 import { createGroupInvite, GroupInviteError } from "@/lib/groups/invites";
 import { getGroupMembership } from "@/lib/groups/permissions";
 import { getGroupBySlug } from "@/lib/groups/queries";
-import { isGroupRole } from "@/lib/groups/utils";
+import { canManageGroupRole, isGroupRole } from "@/lib/groups/utils";
 import type { GroupRole } from "@/lib/db";
 
 export async function POST(
@@ -44,6 +44,10 @@ export async function POST(
       ? body.invitedUsername
       : null;
 
+    if (!canManageGroupRole(membership.role, role)) {
+      return NextResponse.json({ error: "Forbidden" }, { status: 403 });
+    }
+
     const invite = await createGroupInvite({
       groupId: group.id,
       invitedBy: session.id,