In a typical Rack middleware setup, the call method handles the initial request and generates a response, but it does not control subsequent redirects initiated by external services. If an external service, such as Slack's OAuth, triggers additional redirects after your application responds, modifying headers for those redirects within the same call method may not be directly achievable. Handling subsequent redirects may require alternative approaches, such as additional middleware or different parts of your application's code. #rails , #rack , #middleware