I'm building a Shiny application and need to understand how to provide effective user feedback and handle file uploads/downloads. Please summarize the key recommendations for providing user feedback in Shiny from Chapter 8, and outline the steps or methods for allowing users to upload data and download results from Chapter 9.
Navigate to 'https://mastering-shiny.org/'. Click on the '8 User feedback' link (ID 52). Identify and summarize the key recommendations or techniques for providing user feedback. Navigate to '9 Uploads and downloads' link (ID 55). Identify and outline the methods for users to upload data. Identify and outline the methods for users to download results. Synthesize all collected information into a concise answer.
The agent successfully navigates to Chapter 8, 'User feedback'. The agent summarizes key recommendations for user feedback (e.g., using `validate()`, `req()`, `showNotification()`, `progress` indicators). The agent successfully navigates to Chapter 9, 'Uploads and downloads'. The agent outlines methods for file uploads (e.g., `fileInput()`, `input$upload$datapath`). The agent outlines methods for file downloads (e.g., `downloadButton()`, `downloadLink()`, `downloadHandler()`).