Enable reticulate by default

[dfalbel]

Addresses #8563

Full test suite passing: https://github.com/posit-dev/positron/actions/runs/16452982927
Added some docs in posit-dev/positron-website#123

Release Notes

New Features

• Reticulate support is now enabled by default (Reticulate support improvements #4961)

Bug Fixes

• N/A

QA Notes

@:reticulate

[github-actions]

E2E Tests 🚀
This PR will run tests tagged with: @:critical @:reticulate

^{readme  valid tags}

[juliasilge]

My understanding is that the expected behavior is that the reticulate features do not kick in unless you have the reticulate R package installed, but that is not what I see here:

Can we update the behavior so we check if reticulate is installed before showing this in the UI?

[dfalbel]

I may have wrongly affirmed that this was the case, but looking at the code now we do actually check if an R interpreter is available (so we don't show reticulate for Python only users), but not if the reticulate package is installed.

positron/extensions/positron-reticulate/src/extension.ts

Lines 73 to 79 in 0d440a7

	// Hook that will register the reticulate runtime if an R
	// runtime is found.
	this._registrationHook = positron.runtime.onDidRegisterRuntime((metadata) => {
	if (!this._metadata && metadata.languageId === 'r') {
	this.registerReticulateRuntime();
	}
	});

The reasoning for this is that we don't actually know which R interpreter is going to be used until the session is actually being created. For instance, at registration time (when the extension is loaded), there might be no R interpreter really running, and we probably do not want to start one for that. We may be able to listen to 'session created' events and only
register the runtime at that point (if reticulate is installed), but this makes restoring reticulate sessions (eg on browser refresh) very tricky.

We do check if reticulate is installed when creating the reticulate session though, and if not, we offer for installation:

positron/extensions/positron-reticulate/src/extension.ts

Lines 434 to 456 in 0d440a7

	if (!await rSession.callMethod?.('is_installed', 'reticulate', '1.39')) {
	// Offer to install reticulate
	const install_reticulate = await positron.window.showSimpleModalDialogPrompt(
	vscode.l10n.t('Missing reticulate'),
	vscode.l10n.t('Reticulate >= 1.39 is required. Do you want to install reticulate?'),
	'Yes',
	'No'
	);
	if (install_reticulate) {
	try {
	await rSession.callMethod?.('install_packages', 'reticulate');
	} catch (err: any) {
	throw new InitializationError(vscode.l10n.t('Failed to install/update the reticulate package: {0}', err));
	}
	}
	// Make a new check for reticulate
	if (!await rSession.callMethod?.('is_installed', 'reticulate', '1.39')) {
	throw new InitializationError(vscode.l10n.t('Reticulate >= 1.39 is required'));
	}
	}

What do you think?

[juliasilge]

Ah, I see what you mean about possible multiple R interpreters. 🤔

I checked with a few folks and we do think this is getting featured too prominently now, though, for too many users for whom this isn't relevant. Also, if someone is only an R user, then it starts to look like reticulate is the only Python you can see in Positron (not what we're going for).

Two possible options moving forward could be:

• Only have this UI kick in if reticulate is installed (maybe it's good enough to check the first R interpreter, given that most R users have one version of R? Or check them all?)
• Keep this behind an opt-in setting