diff --git a/backend/ent/schema/auth_identity_schema_test.go b/backend/ent/schema/auth_identity_schema_test.go
index fbb93236..d3e24050 100644
--- a/backend/ent/schema/auth_identity_schema_test.go
+++ b/backend/ent/schema/auth_identity_schema_test.go
@@ -83,10 +83,10 @@ func TestAuthIdentityFoundationSchemas(t *testing.T) {
 	require.Equal(t, 1, signupSource.Validators)
 
 	validator := requireStringFieldValidator(t, User{}.Fields(), "signup_source")
-	for _, value := range []string{"email", "linuxdo", "wechat", "oidc"} {
+	for _, value := range []string{"email", "linuxdo", "wechat", "oidc", "github", "google"} {
 		require.NoError(t, validator(value))
 	}
-	require.Error(t, validator("github"))
+	require.Error(t, validator("unknown"))
 }
 
 func requireSchema(t *testing.T, schemas map[string]*load.Schema, name string) *load.Schema {
diff --git a/backend/internal/server/api_contract_test.go b/backend/internal/server/api_contract_test.go
index 34f560fc..84259050 100644
--- a/backend/internal/server/api_contract_test.go
+++ b/backend/internal/server/api_contract_test.go
@@ -685,6 +685,16 @@ func TestAPIContracts(t *testing.T) {
 						"oidc_connect_userinfo_email_path": "",
 						"oidc_connect_userinfo_id_path": "",
 						"oidc_connect_userinfo_username_path": "",
+						"github_oauth_enabled": false,
+						"github_oauth_client_id": "",
+						"github_oauth_client_secret_configured": false,
+						"github_oauth_redirect_url": "",
+						"github_oauth_frontend_redirect_url": "/auth/oauth/callback",
+						"google_oauth_enabled": false,
+						"google_oauth_client_id": "",
+						"google_oauth_client_secret_configured": false,
+						"google_oauth_redirect_url": "",
+						"google_oauth_frontend_redirect_url": "/auth/oauth/callback",
 						"ops_monitoring_enabled": false,
 						"ops_realtime_monitoring_enabled": true,
 						"ops_query_mode_default": "auto",
@@ -700,6 +710,16 @@ func TestAPIContracts(t *testing.T) {
 					"auth_source_default_email_subscriptions": [],
 					"auth_source_default_email_grant_on_signup": false,
 					"auth_source_default_email_grant_on_first_bind": false,
+					"auth_source_default_github_balance": 0,
+					"auth_source_default_github_concurrency": 5,
+					"auth_source_default_github_subscriptions": [],
+					"auth_source_default_github_grant_on_signup": false,
+					"auth_source_default_github_grant_on_first_bind": false,
+					"auth_source_default_google_balance": 0,
+					"auth_source_default_google_concurrency": 5,
+					"auth_source_default_google_subscriptions": [],
+					"auth_source_default_google_grant_on_signup": false,
+					"auth_source_default_google_grant_on_first_bind": false,
 					"auth_source_default_linuxdo_balance": 0,
 					"auth_source_default_linuxdo_concurrency": 5,
 					"auth_source_default_linuxdo_subscriptions": [],
@@ -898,6 +918,16 @@ func TestAPIContracts(t *testing.T) {
 					"oidc_connect_userinfo_email_path": "",
 					"oidc_connect_userinfo_id_path": "",
 					"oidc_connect_userinfo_username_path": "",
+					"github_oauth_enabled": false,
+					"github_oauth_client_id": "",
+					"github_oauth_client_secret_configured": false,
+					"github_oauth_redirect_url": "",
+					"github_oauth_frontend_redirect_url": "/auth/oauth/callback",
+					"google_oauth_enabled": false,
+					"google_oauth_client_id": "",
+					"google_oauth_client_secret_configured": false,
+					"google_oauth_redirect_url": "",
+					"google_oauth_frontend_redirect_url": "/auth/oauth/callback",
 					"site_name": "Sub2API",
 					"site_logo": "",
 					"site_subtitle": "Subscription to API Conversion Platform",
@@ -1005,6 +1035,16 @@ func TestAPIContracts(t *testing.T) {
 					"auth_source_default_email_subscriptions": [],
 					"auth_source_default_email_grant_on_signup": false,
 					"auth_source_default_email_grant_on_first_bind": false,
+					"auth_source_default_github_balance": 0,
+					"auth_source_default_github_concurrency": 5,
+					"auth_source_default_github_subscriptions": [],
+					"auth_source_default_github_grant_on_signup": false,
+					"auth_source_default_github_grant_on_first_bind": false,
+					"auth_source_default_google_balance": 0,
+					"auth_source_default_google_concurrency": 5,
+					"auth_source_default_google_subscriptions": [],
+					"auth_source_default_google_grant_on_signup": false,
+					"auth_source_default_google_grant_on_first_bind": false,
 					"auth_source_default_linuxdo_balance": 0,
 					"auth_source_default_linuxdo_concurrency": 5,
 					"auth_source_default_linuxdo_subscriptions": [],
diff --git a/backend/internal/service/auth_oauth_email_flow_test.go b/backend/internal/service/auth_oauth_email_flow_test.go
index 21d9d6e9..cd76c6b7 100644
--- a/backend/internal/service/auth_oauth_email_flow_test.go
+++ b/backend/internal/service/auth_oauth_email_flow_test.go
@@ -229,6 +229,67 @@ func TestRegisterOAuthEmailAccountSetsNormalizedSignupSourceOnCreatedUser(t *tes
 	require.Equal(t, "oidc", userRepo.created[0].SignupSource)
 }
 
+func TestRegisterOAuthEmailAccountKeepsGitHubAndGoogleSignupSource(t *testing.T) {
+	tests := []struct {
+		name         string
+		email        string
+		signupSource string
+		want         string
+	}{
+		{
+			name:         "github",
+			email:        "github@example.com",
+			signupSource: " GitHub ",
+			want:         "github",
+		},
+		{
+			name:         "google",
+			email:        "google@example.com",
+			signupSource: " Google ",
+			want:         "google",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			userRepo := &userRepoStub{nextID: 43}
+			emailCache := &emailCacheStub{
+				data: &VerificationCodeData{
+					Code:      "246810",
+					Attempts:  0,
+					CreatedAt: time.Now().UTC(),
+					ExpiresAt: time.Now().UTC().Add(15 * time.Minute),
+				},
+			}
+			authService := newOAuthEmailFlowAuthService(
+				userRepo,
+				&redeemCodeRepoStub{},
+				&refreshTokenCacheStub{},
+				map[string]string{
+					SettingKeyRegistrationEnabled: "true",
+					SettingKeyEmailVerifyEnabled:  "true",
+				},
+				emailCache,
+			)
+
+			tokenPair, user, err := authService.RegisterOAuthEmailAccount(
+				context.Background(),
+				tt.email,
+				"secret-123",
+				"246810",
+				"",
+				tt.signupSource,
+			)
+
+			require.NoError(t, err)
+			require.NotNil(t, tokenPair)
+			require.NotNil(t, user)
+			require.Len(t, userRepo.created, 1)
+			require.Equal(t, tt.want, userRepo.created[0].SignupSource)
+		})
+	}
+}
+
 func TestRegisterOAuthEmailAccountFallsBackUnknownSignupSourceToEmail(t *testing.T) {
 	userRepo := &userRepoStub{nextID: 43}
 	emailCache := &emailCacheStub{
@@ -256,7 +317,7 @@ func TestRegisterOAuthEmailAccountFallsBackUnknownSignupSourceToEmail(t *testing
 		"secret-123",
 		"246810",
 		"",
-		"github",
+		"unknown-provider",
 	)
 
 	require.NoError(t, err)