feat(*): 云端 Agent - 增强画布上下文读取并接入 Gemini 缓存

backend/internal/database/migrations.go

@@ -11,7 +11,7 @@ import (
 	"gorm.io/gorm"
 )
 
-const CurrentSchemaVersion int64 = 35
+const CurrentSchemaVersion int64 = 37
 
 const baselineSchemaChecksum = "sha256:open-ai-canvas-schema-v1-20260830"
 const schemaMigrationAppliedAtIndexChecksum = "sha256:schema-migrations-applied-at-index-v2-20260830"
@@ -23,6 +23,8 @@ const assetLibraryFoldersChecksum = "sha256:asset-library-folders-v6-20260902"
 const logicalModelActiveCodeChecksum = "sha256:logical-model-active-code-v8-20260905"
 const creationRuntimeChecksum = "sha256:creation-runtime-v10-20260909"
 const authNotificationsChecksum = "sha256:auth-notifications-v35-20260924"
+const cloudAgentGeminiCacheChecksum = "sha256:cloud-agent-gemini-cache-v36-20260924"
+const cloudAgentGeminiCacheIdentityChecksum = "sha256:cloud-agent-gemini-cache-identity-v37-20260925"
 
 const postgresSchemaMigrationLockID int64 = 73123910420260830
 
@@ -119,6 +121,24 @@ var schemaMigrations = []migration{
 		return nil
 	}},
 	{version: 35, name: "auth_notifications", checksum: authNotificationsChecksum, apply: migrateSchemaV35},
+	{version: 36, name: "cloud_agent_gemini_cache", checksum: cloudAgentGeminiCacheChecksum, apply: func(tx *gorm.DB) error {
+		return tx.AutoMigrate(&model.CloudAgentGeminiCache{})
+	}},
+	{version: 37, name: "cloud_agent_gemini_cache_identity", checksum: cloudAgentGeminiCacheIdentityChecksum, apply: migrateCloudAgentGeminiCacheIdentity},
+}
+
+func migrateCloudAgentGeminiCacheIdentity(tx *gorm.DB) error {
+	// v36 accidentally made cache_key globally unique while repository reads and
+	// writes are user-scoped. Remove that index before creating the explicit
+	// (user_id, cache_key) identity used by the model tags.
+	for _, name := range []string{"idx_cloud_agent_gemini_caches_cache_key", "idx_cloud_agent_gemini_cache_cache_key"} {
+		if tx.Migrator().HasIndex(&model.CloudAgentGeminiCache{}, name) {
+			if err := tx.Migrator().DropIndex(&model.CloudAgentGeminiCache{}, name); err != nil {
+				return fmt.Errorf("删除 Gemini 缓存旧唯一索引 %s：%w", name, err)
+			}
+		}
+	}
+	return tx.AutoMigrate(&model.CloudAgentGeminiCache{})
 }
 
 func migrateChannelModelTags(tx *gorm.DB) error {

backend/internal/database/migrations_test.go

@@ -78,6 +78,9 @@ func TestMigrateSchemaRecordsAndValidatesVersion(t *testing.T) {
 		!db.Migrator().HasColumn(&model.EmailVerificationCode{}, "attempts") {
 		t.Fatal("schema migration v35 did not add authentication verification fields")
 	}
+	if !db.Migrator().HasTable(&model.CloudAgentGeminiCache{}) {
+		t.Fatal("schema migration v36 did not create Gemini cache table")
+	}
 	if err := MigrateSchema(db); err != nil {
 		t.Fatalf("migration should be idempotent: %v", err)
 	}

backend/internal/database/schema.go

@@ -21,6 +21,7 @@ func Models() []any {
 		&model.CloudAgentMessageRecord{},
 		&model.CloudAgentCanvasMutation{},
 		&model.CloudAgentResourceLease{},
+		&model.CloudAgentGeminiCache{},
 		&model.AgentProfile{},
 		&model.AgentLesson{},
 		&model.AgentMemorySetting{},