Feature Request: Debug Shiny App (for R shiny)

[jeffkeller-einc]

Loving Positron and the extensions so far but one area where the experience is a step backward compared to RStudio is debugging R shiny apps. Being able to set breakpoints within reactives is incredible useful when developing non-trivial apps. Would be great to have debugging capabilities for R shiny apps in addition to Python shiny apps.

Related to:

#12
#17

[gadenbuie]

Agreed and I know that the Positron team will bring break-point debugging in R files to Positron soon. When that happens we'll look into adding debugging support here for Shiny for R apps.

In the mean time, for the best experience in Positron, add browser() statements where you'd want to add breakpoints and run the app from the Console rather than using the extension. I know this isn't the ideal way to enter debugging, but once you've made it into the debugger, the experience in Positron is pretty good.

[dleopold]

I saw some debugging updates in the most recent positron release and am wondering if there is any movement towards improving the shiny debugging workflow in positron by supporting browser() statements in the extension.

[carlocav]

Breakpoint debugging in R files is now supported!

[juliasilge]

We have another request on this in posit-dev/positron#11764.

[dleopold]

Breakpoint debugging in R files is now supported!

But this does not work when running a shiny app via the extension. I am surprised there are not more requests / comments about this.

[carlocav]

Breakpoint debugging in R files is now supported!

But this does not work when running a shiny app via the extension. I am surprised there are not more requests / comments about this.

It also doesn’t work running it with runApp, so as far as I know the only way to debug an app is with browse() calls. Not sure why there are few requests, I have the impression most R Shiny developers still use RStudio

[juliasilge]

We have outlined some additional thoughts in posit-dev/positron#11784.

[lionel-]

Note that breakpoints already work in the latest release of Positron if you run shinyApp() via an editor. We need to finalise the integration for runApp().

Screen.Recording.2026-02-10.at.10.24.47.mov

[carlocav]

Good to know, I didn’t know about this way of running a shiny app. Does it work also with separate ui, server and global files?

[gadenbuie]

Does it work also with separate ui, server and global files?

It should work with ui/server/global files if you interactively source or run them like @lionel- did in the screencast. It unlikely that it would work if you rely on Shiny's internal handling of supporting files – this will be fixed when we establish an integration for runApp()