Method refreshSlack

src/main/lib/credential-manager.ts:655–677

* Refresh Slack OAuth token

(
    source: LoadedSource,
    cred: StoredCredential
  )

   * Refresh Slack OAuth token
   */
  private async refreshSlack(
    source: LoadedSource,
    cred: StoredCredential
  ): Promise<string | null> {
    try {
      const result = await refreshSlackToken(cred.refreshToken!, cred.clientId);

      // Update stored credentials
      await this.save(source, {
        ...cred,
        value: result.accessToken,
        expiresAt: result.expiresAt,
      });

      debug(`[SourceCredentialManager] Refreshed Slack token for ${source.config.slug}`);
      return result.accessToken;
    } catch (error) {
      const errorMsg = error instanceof Error ? error.message : String(error);
      debug(`[SourceCredentialManager] Slack token refresh failed:`, error);
      this.markSourceNeedsReauth(source, `Token refresh failed: ${errorMsg}`);
      return null;
    }
  }

  /**
   * Refresh Microsoft OAuth token