Support 'Julia for Positron' extension (ntluong.julia-positron) for Julia cell execution in Positron IDE

[DevenVGokhale]

Summary

When using Quarto .qmd files with engine: julia in Positron (the data science IDE by Posit, built on VS Code), executing Julia code chunks fails with:

Executing julia cells requires the Julia extension.

Root Cause

The Quarto VS Code extension checks specifically for the julialang.language-julia extension to enable Julia cell execution. However, julialang.language-julia is incompatible with Positron due to a VS Code engine version mismatch:

Cannot install 'julialang.language-julia' extension because of version mismatch in Marketplace

Positron currently ships with VS Code engine 1.109.2, while the latest julialang.language-julia requires a higher engine version.

The Fix

There is a community extension — Julia for Positron (ntluong.julia-positron) — specifically built to provide Julia REPL/console integration within Positron's architecture. Quarto should recognize this extension as a valid Julia provider in addition to julialang.language-julia.

Request

Please update the extension detection logic to also accept ntluong.julia-positron (or any extension that exposes the required executeInREPL API) so that Julia cell execution works in Positron without requiring the incompatible julialang.language-julia.

Environment

• IDE: Positron 1.109.2
• Extension: Julia for Positron (ntluong.julia-positron)
• OS: macOS

[DevenVGokhale]

Root cause found

After digging into the Quarto extension source (~/.positron/extensions/quarto.quarto-1.132.0-universal/out/main.js), the issue is a missing case "julia" in the cellExecutorForLanguage switch statement inside the Dne() function (the Positron-specific executor):

cellExecutorForLanguage: async (t, e, r, n) => {
  switch (t) {
    case "python":
    case "csharp":
    case "r":
      return {
        execute: async (...) => { ... s.executeCode(t, ...) },
        executeSelection: async () => {
          await commands.executeCommand(
            "workbench.action.positronConsole.executeCode",
            { languageId: t }
          )
        },
        ...
      }
    // ❌ No case for "julia" — falls through to undefined
  }
}

R and Python are routed through workbench.action.positronConsole.executeCode which hooks into Positron's native console. Julia has no case at all, so cellExecutorForLanguage returns undefined, and the subsequent call to undefined.executeInREPL(...) throws:

Cannot read properties of undefined (reading 'executeInREPL')

Fix

Add a case "julia" that routes through the same workbench.action.positronConsole.executeCode path, using the ntluong95.positron-julia extension's registered languageRuntime for Julia. The ntluong95.positron-julia extension already registers Julia as a languageRuntime with Positron's API, so the runtime session should be available via H3()?.runtime.executeCode("julia", ...).