From b6ee9f0a320cbdd980c68e916ff551e1feb573a0 Mon Sep 17 00:00:00 2001
From: 22zyfeng-collab <241945674+22zyfeng-collab@users.noreply.github.com>
Date: Tue, 8 Sep 2026 15:02:32 +0800
Subject: [PATCH] fix(antigravity): preserve OAuth subscription plan across
 account creation

---
 .../service/antigravity_oauth_service.go      |  2 +-
 .../service/antigravity_oauth_service_test.go | 24 +++++++++++++++++++
 frontend/src/api/admin/antigravity.ts         |  1 +
 .../__tests__/useAntigravityOAuth.spec.ts     | 14 +++++++++++
 .../src/composables/useAntigravityOAuth.ts    |  3 ++-
 5 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/backend/internal/service/antigravity_oauth_service.go b/backend/internal/service/antigravity_oauth_service.go
index 3a4600db0e..5d4390d9cf 100644
--- a/backend/internal/service/antigravity_oauth_service.go
+++ b/backend/internal/service/antigravity_oauth_service.go
@@ -90,7 +90,7 @@ type AntigravityTokenInfo struct {
 	Email            string `json:"email,omitempty"`
 	ProjectID        string `json:"project_id,omitempty"`
 	ProjectIDMissing bool   `json:"-"`
-	PlanType         string `json:"-"`
+	PlanType         string `json:"plan_type,omitempty"`
 	PrivacyMode      string `json:"-"`
 }
 
diff --git a/backend/internal/service/antigravity_oauth_service_test.go b/backend/internal/service/antigravity_oauth_service_test.go
index 1d2d823557..c89b3f0a44 100644
--- a/backend/internal/service/antigravity_oauth_service_test.go
+++ b/backend/internal/service/antigravity_oauth_service_test.go
@@ -1,6 +1,7 @@
 package service
 
 import (
+	"encoding/json"
 	"testing"
 )
 
@@ -80,3 +81,26 @@ func TestResolveDefaultTierID(t *testing.T) {
 		})
 	}
 }
+
+// The OAuth handler serializes this DTO before the browser creates or reauthorizes an account.
+func TestAntigravityTokenInfoPreservesPlanTypeJSON(t *testing.T) {
+	for _, plan := range []string{"pro", "ultra", "free", ""} {
+		t.Run(plan, func(t *testing.T) {
+			data, err := json.Marshal(AntigravityTokenInfo{PlanType: plan})
+			if err != nil {
+				t.Fatal(err)
+			}
+			var response map[string]any
+			if err := json.Unmarshal(data, &response); err != nil {
+				t.Fatal(err)
+			}
+			if plan == "" {
+				if _, exists := response["plan_type"]; exists {
+					t.Fatal("unknown plan must remain omitted")
+				}
+			} else if response["plan_type"] != plan {
+				t.Fatalf("OAuth response plan_type = %v, want %q", response["plan_type"], plan)
+			}
+		})
+	}
+}
diff --git a/frontend/src/api/admin/antigravity.ts b/frontend/src/api/admin/antigravity.ts
index 779fa9c1f8..7b351fab8e 100644
--- a/frontend/src/api/admin/antigravity.ts
+++ b/frontend/src/api/admin/antigravity.ts
@@ -29,6 +29,7 @@ export interface AntigravityTokenInfo {
   expires_at?: number | string
   expires_in?: number
   project_id?: string
+  plan_type?: string
   email?: string
   [key: string]: unknown
 }
diff --git a/frontend/src/composables/__tests__/useAntigravityOAuth.spec.ts b/frontend/src/composables/__tests__/useAntigravityOAuth.spec.ts
index fcb6f48b18..511f28b2be 100644
--- a/frontend/src/composables/__tests__/useAntigravityOAuth.spec.ts
+++ b/frontend/src/composables/__tests__/useAntigravityOAuth.spec.ts
@@ -54,3 +54,17 @@ describe('useAntigravityOAuth.buildCredentials', () => {
     expect(credentials.refresh_token).toBe('rotated-refresh-token')
   })
 })
+
+// This builder is shared by OAuth creation, refresh-token import and reauthorization.
+describe('Antigravity subscription metadata', () => {
+  it.each(['pro', 'ultra', 'free'])('preserves the upstream %s plan when saving credentials', (plan) => {
+    const oauth = useAntigravityOAuth()
+    const credentials = oauth.buildCredentials({ plan_type: plan })
+    expect(credentials.plan_type).toBe(plan)
+  })
+
+  it('does not invent a plan when subscription discovery is unavailable', () => {
+    const credentials = useAntigravityOAuth().buildCredentials({})
+    expect(credentials).not.toHaveProperty('plan_type')
+  })
+})
diff --git a/frontend/src/composables/useAntigravityOAuth.ts b/frontend/src/composables/useAntigravityOAuth.ts
index f480ea20bc..df0d264c0e 100644
--- a/frontend/src/composables/useAntigravityOAuth.ts
+++ b/frontend/src/composables/useAntigravityOAuth.ts
@@ -132,7 +132,8 @@ export function useAntigravityOAuth() {
       token_type: tokenInfo.token_type,
       expires_at: expiresAt,
       project_id: tokenInfo.project_id,
-      email: tokenInfo.email
+      email: tokenInfo.email,
+      ...(tokenInfo.plan_type ? { plan_type: tokenInfo.plan_type } : {})
     }
   }