diff --git a/cmd/server/tests/device_test.go b/cmd/server/tests/device_test.go
index 0aa82ed..095434c 100644
--- a/cmd/server/tests/device_test.go
+++ b/cmd/server/tests/device_test.go
@@ -322,3 +322,207 @@ func TestRejectDeviceRegistration(t *testing.T) {
 
 	assert.Equal(t, "device registration rejected", rejectResponse["message"], "Should confirm rejection message")
 }
+
+func TestRegenerateDeviceToken_Success(t *testing.T) {
+	setup := setupDeviceTest(t)
+	defer setup.Server.Close()
+
+	// Create a device
+	device := setup.CreateDevice(t, "Test Device", "koreader", "test-device-123")
+	oldToken := device.AuthToken
+
+	// Regenerate token
+	req := httptest.NewRequest("PUT", fmt.Sprintf("/api/devices/%s/regenerate-token", device.ID.String()), nil)
+	req.Header.Set("Authorization", "Bearer "+setup.UserToken)
+	rec := httptest.NewRecorder()
+	setup.Server.Config.Handler.ServeHTTP(rec, req)
+
+	assert.Equal(t, http.StatusOK, rec.Code, "Should regenerate token")
+
+	var response map[string]interface{}
+	json.Unmarshal(rec.Body.Bytes(), &response)
+
+	assert.True(t, response["message"].(string) != "", "Should have success message")
+
+	newToken, ok := response["auth_token"].(string)
+	assert.True(t, ok, "Should have auth_token")
+	assert.NotEmpty(t, newToken, "New token should not be empty")
+	assert.NotEqual(t, oldToken, newToken, "New token should be different from old token")
+
+	// Verify device info is returned
+	deviceInfo, ok := response["device"].(map[string]interface{})
+	assert.True(t, ok, "Should have device info")
+	assert.Equal(t, "Test Device", deviceInfo["device_name"], "Should return device name")
+
+	// Verify sync URLs are returned
+	syncURLs, ok := response["sync_urls"].(map[string]interface{})
+	assert.True(t, ok, "Should have sync_urls")
+	assert.Contains(t, syncURLs, "progress", "Should have progress URL")
+	assert.Contains(t, syncURLs, "metadata", "Should have metadata URL")
+}
+
+func TestRegenerateDeviceToken_OldTokenInvalidated(t *testing.T) {
+	setup := setupDeviceTest(t)
+	defer setup.Server.Close()
+
+	// Create a device
+	device := setup.CreateDevice(t, "Test Device", "koreader", "test-device-invalidated")
+
+	// Test old token works initially
+	req1 := httptest.NewRequest("POST", "/api/sync/koreader/progress", nil)
+	req1.Header.Set("Authorization", "Bearer "+device.AuthToken)
+	req1.Header.Set("Content-Type", "application/json")
+	rec1 := httptest.NewRecorder()
+	setup.Server.Config.Handler.ServeHTTP(rec1, req1)
+	// May fail for other reasons (no data), but should not be unauthorized
+	assert.NotEqual(t, http.StatusUnauthorized, rec1.Code, "Old token should work initially")
+
+	// Regenerate token
+	req2 := httptest.NewRequest("PUT", fmt.Sprintf("/api/devices/%s/regenerate-token", device.ID.String()), nil)
+	req2.Header.Set("Authorization", "Bearer "+setup.UserToken)
+	rec2 := httptest.NewRecorder()
+	setup.Server.Config.Handler.ServeHTTP(rec2, req2)
+	assert.Equal(t, http.StatusOK, rec2.Code, "Should regenerate token")
+
+	var response map[string]interface{}
+	json.Unmarshal(rec2.Body.Bytes(), &response)
+	newToken := response["auth_token"].(string)
+
+	// Test old token no longer works
+	req3 := httptest.NewRequest("POST", "/api/sync/koreader/progress", nil)
+	req3.Header.Set("Authorization", "Bearer "+device.AuthToken)
+	req3.Header.Set("Content-Type", "application/json")
+	rec3 := httptest.NewRecorder()
+	setup.Server.Config.Handler.ServeHTTP(rec3, req3)
+	assert.Equal(t, http.StatusUnauthorized, rec3.Code, "Old token should be invalid after regeneration")
+
+	// Test new token works
+	req4 := httptest.NewRequest("POST", "/api/sync/koreader/progress", nil)
+	req4.Header.Set("Authorization", "Bearer "+newToken)
+	req4.Header.Set("Content-Type", "application/json")
+	rec4 := httptest.NewRecorder()
+	setup.Server.Config.Handler.ServeHTTP(rec4, req4)
+	// May fail for other reasons, but should not be unauthorized
+	assert.NotEqual(t, http.StatusUnauthorized, rec4.Code, "New token should work")
+}
+
+func TestRegenerateDeviceToken_Unauthorized(t *testing.T) {
+	setup := setupDeviceTest(t)
+	defer setup.Server.Close()
+
+	device := setup.CreateDevice(t, "Test Device", "koreader", "test-device-unauth")
+
+	// Try to regenerate without JWT token
+	req := httptest.NewRequest("PUT", fmt.Sprintf("/api/devices/%s/regenerate-token", device.ID.String()), nil)
+	rec := httptest.NewRecorder()
+	setup.Server.Config.Handler.ServeHTTP(rec, req)
+
+	assert.Equal(t, http.StatusUnauthorized, rec.Code, "Should require authentication")
+
+	var response map[string]interface{}
+	json.Unmarshal(rec.Body.Bytes(), &response)
+	assert.Contains(t, response, "error", "Should return error message")
+}
+
+func TestRegenerateDeviceToken_Forbidden(t *testing.T) {
+	setup := setupDeviceTest(t)
+	defer setup.Server.Close()
+
+	// Create device for user 1
+	device1 := setup.CreateDevice(t, "User1 Device", "koreader", "user1-device")
+
+	// Create a second user with different credentials
+	ctx := context.Background()
+	passwordHash := "$2a$10$JjAtK7PPa1WexQC3AUGe8OXLeuseZ/haN1Mz7emMo6CfOvMiTVXWq"
+	_, err := setup.DB.CreateUser(ctx, database.CreateUserParams{
+		Email:        "differentuser@example.com",
+		Username:     "differentuser",
+		PasswordHash: passwordHash,
+		FirstName:    pgtype.Text{String: "Different", Valid: true},
+		LastName:     pgtype.Text{String: "User", Valid: true},
+		Role:         "user",
+	})
+	assert.NoError(t, err)
+
+	// Login as user 2
+	loginRequest := map[string]interface{}{
+		"login":    "differentuser@example.com",
+		"password": "Test@Pass123!",
+	}
+	loginBody, _ := json.Marshal(loginRequest)
+	loginReq := httptest.NewRequest("POST", "/api/auth/login", bytes.NewReader(loginBody))
+	loginReq.Header.Set("Content-Type", "application/json")
+	loginRec := httptest.NewRecorder()
+	setup.Server.Config.Handler.ServeHTTP(loginRec, loginReq)
+
+	var loginResponse map[string]interface{}
+	json.Unmarshal(loginRec.Body.Bytes(), &loginResponse)
+	user2Token := loginResponse["access_token"].(string)
+
+	// Try to regenerate user 1's device with user 2's token
+	req := httptest.NewRequest("PUT", fmt.Sprintf("/api/devices/%s/regenerate-token", device1.ID.String()), nil)
+	req.Header.Set("Authorization", "Bearer "+user2Token)
+	rec := httptest.NewRecorder()
+	setup.Server.Config.Handler.ServeHTTP(rec, req)
+
+	assert.Equal(t, http.StatusForbidden, rec.Code, "Should forbid access to other user's device")
+
+	var response map[string]interface{}
+	json.Unmarshal(rec.Body.Bytes(), &response)
+	assert.Contains(t, response, "error", "Should return error message")
+}
+
+func TestRegenerateDeviceToken_NotFound(t *testing.T) {
+	setup := setupDeviceTest(t)
+	defer setup.Server.Close()
+
+	fakeDeviceID, _ := uuid.NewUUID()
+
+	// Try to regenerate non-existent device
+	req := httptest.NewRequest("PUT", fmt.Sprintf("/api/devices/%s/regenerate-token", fakeDeviceID.String()), nil)
+	req.Header.Set("Authorization", "Bearer "+setup.UserToken)
+	rec := httptest.NewRecorder()
+	setup.Server.Config.Handler.ServeHTTP(rec, req)
+
+	assert.Equal(t, http.StatusNotFound, rec.Code, "Should return not found")
+
+	var response map[string]interface{}
+	json.Unmarshal(rec.Body.Bytes(), &response)
+	assert.Contains(t, response, "error", "Should return error message")
+}
+
+func TestRegenerateDeviceToken_KoboDevice(t *testing.T) {
+	setup := setupDeviceTest(t)
+	defer setup.Server.Close()
+
+	// Create a Kobo device
+	koboDevice := setup.CreateDevice(t, "Test Kobo", "kobo", "test-kobo-regen")
+	oldToken := koboDevice.AuthToken
+
+	// Regenerate token
+	req := httptest.NewRequest("PUT", fmt.Sprintf("/api/devices/%s/regenerate-token", koboDevice.ID.String()), nil)
+	req.Header.Set("Authorization", "Bearer "+setup.UserToken)
+	rec := httptest.NewRecorder()
+	setup.Server.Config.Handler.ServeHTTP(rec, req)
+
+	assert.Equal(t, http.StatusOK, rec.Code, "Should regenerate token")
+
+	var response map[string]interface{}
+	json.Unmarshal(rec.Body.Bytes(), &response)
+
+	newToken := response["auth_token"].(string)
+	assert.NotEqual(t, oldToken, newToken, "New token should be different")
+
+	// Verify Kobo sync URLs are returned
+	syncURLs, ok := response["sync_urls"].(map[string]interface{})
+	assert.True(t, ok, "Should have sync_urls")
+	assert.Contains(t, syncURLs, "sync_url", "Should have sync_url")
+	assert.Contains(t, syncURLs, "markup", "Should have markup URL")
+	assert.Contains(t, syncURLs, "bookmark", "Should have bookmark URL")
+	assert.Contains(t, syncURLs, "init", "Should have init URL")
+
+	// Verify URLs contain new token
+	syncURL := syncURLs["sync_url"].(string)
+	assert.Contains(t, syncURL, newToken, "Sync URL should contain new token")
+	assert.NotContains(t, syncURL, oldToken, "Sync URL should not contain old token")
+}