feat(backend): add kiro account support

backend/internal/service/kiro_token_refresher.go

@@ -0,0 +1,47 @@
+package service
+
+import (
+	"context"
+	"time"
+)
+
+const kiroRefreshWindow = 15 * time.Minute
+
+type KiroTokenRefresher struct {
+	kiroOAuthService *KiroOAuthService
+}
+
+func NewKiroTokenRefresher(kiroOAuthService *KiroOAuthService) *KiroTokenRefresher {
+	return &KiroTokenRefresher{
+		kiroOAuthService: kiroOAuthService,
+	}
+}
+
+func (r *KiroTokenRefresher) CacheKey(account *Account) string {
+	return KiroTokenCacheKey(account)
+}
+
+func (r *KiroTokenRefresher) CanRefresh(account *Account) bool {
+	return account != nil && account.Platform == PlatformKiro && account.Type == AccountTypeOAuth
+}
+
+func (r *KiroTokenRefresher) NeedsRefresh(account *Account, _ time.Duration) bool {
+	if !r.CanRefresh(account) {
+		return false
+	}
+	expiresAt := account.GetCredentialAsTime("expires_at")
+	if expiresAt == nil {
+		return false
+	}
+	return time.Until(*expiresAt) <= kiroRefreshWindow
+}
+
+func (r *KiroTokenRefresher) Refresh(ctx context.Context, account *Account) (map[string]any, error) {
+	tokenInfo, err := r.kiroOAuthService.RefreshAccountToken(ctx, account)
+	if err != nil {
+		return nil, err
+	}
+
+	newCredentials := r.kiroOAuthService.BuildAccountCredentials(tokenInfo)
+	return MergeCredentials(account.Credentials, newCredentials), nil
+}