Behavior of `options(browse =)` outside of Positron

[DavisVaughan]

Right now we always override options(browse =) and add our special Positron specific behavior. This isn't great for Jupyter kernels

ark/crates/ark/src/browser.rs

Lines 37 to 59 in 738afba

	unsafe fn ps_browse_url_impl(url: SEXP) -> anyhow::Result<SEXP> {
	// Extract URL.
	let url = RObject::view(url).to::<String>()?;
	let _span = tracing::trace_span!("browseURL", url = %url).entered();
	// Handle help server requests.
	if is_help_url(&url) {
	log::trace!("Help is handling URL");
	handle_help_url(url)?;
	return Ok(Rf_ScalarLogical(1));
	} else {
	log::trace!("Help is not handling URL");
	}
	// For all other URLs, create a ShowUrl event and send it to the main
	// thread; Positron will handle it.
	let params = ShowUrlParams { url };
	let event = UiFrontendEvent::ShowUrl(params);
	RMain::with(|main| main.send_frontend_event(event));
	Ok(Rf_ScalarLogical(1))
	}

From @lionel-

The right thing to do outside Positron is to use the default action, i.e. open in a web browser. So we should not set up that option unless Positron is connected. Ideally Positron would inject the option via its init file. Or the UI comm could launch an idle task to do it, but there would a short time where the option is not set with this approach.

[jennybc]

Specifically, in PR #877, here's the sort of error raised by calling browseURL() on a local folder's filepath:

~/tmp % jupyter console --kernel=ark
Jupyter console 6.6.3


R version 4.4.2 (2024-10-31) -- "Pile of Leaves"
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Platform: aarch64-apple-darwin20

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In [1]: browseURL("~/tmp")
  2025-07-21T21:35:02.025887Z ERROR  No help port is available to check if '~/tmp' is a help url. Is the help comm open?
    at crates/ark/src/interface.rs:2032

  2025-07-21T21:35:02.026935Z ERROR  Failed to browse url due to: UI comm not connected, can't run `open_with_system`.
    at crates/ark/src/browser.rs:22


In [2]: getOption("browser")
Out[2]:
function(url) {
    .ps.Call("ps_browse_url", as.character(url))
}
<environment: 0x11fd5bc70>

[DavisVaughan]

I think we need some guards in our (currently unconditional) options( setting calls that only set the options when we are in Positron. We will probably have to gather a number of options( calls that are specific to Positron features together and set them in one if (is_position()) { branch, and avoid them otherwise