I am having an issue with documents such as Word and Excel being downloaded instead of opened via Office when accessed via a direct URL in SP 2013. I might expect this behavior in Chrome or Firefox, but it is also happening in IE 9. In researching, I have have found many discussions about this happening in SP 2010 (example), but it seems like it should just work in 2013. The site is in the Local Intranet zone. The Web Application's "Browser File Handling" settings are "Permissive". Any suggestions?
Edit: After further testing, I am only able to replicate this with the URL that is sent out via the "Share" feature. The URL appears to be appending "?web=1" presumably telling SP to use the browser to open it. We are not running Office Web Apps and so this flag seems inappropriate. I found someone else describing the same issue but the solution provided to modify the SharePoint call outs seemed drastic. SharePoint can't handle this itself?
Edit2: After additional testing, this issue seems to be isolated to Excel files. Word documents seem to work fine. That is, when I share an Excel file from a document library via the "Share" link, the link contains "?web=1" at the end and users experience the problems described. A Word document shared in the same way from the same library does not have the "?web=1" appended and behaves as expected.