Positron Assistant: GitHub Copilot and Claude-Powered Agentic Coding in R
Positron Assistant provides inline completions with GitHub Copilot and chat using Claude 4 Sonnet. Demonstration: using agent mode to create an R package with Roxygen2 docs and testthat unit tests.
I have a little hobby project I’m working on and I wanted to use the opportunity to fully make the switch to Positron from RStudio. I used Positron here and there when it first came out, but now that it’s out of beta and has a more complete feature set (like remote SSH sessions!) I have everything I need to switch and not look back. The most exciting new addition is the new Positron Assistant.
Positron Assistant
I wrote a post last year about AI code completion in Positron. GitHub copilot wouldn’t work in Positron at the time so I tried out Codeium, Tabnine, and Continue.
Using a third-party plugin is no longer necessary. One of the more exciting new features in Positron is Positron Assistant.1 From the description:
Positron Assistant is an AI client that provides LLM integration within Positron, both for chat and for inline completions. Use Positron Assistant to generate or refactor code, ask questions, get help with debugging, and get suggestions for next steps in your data science projects.
Positron Assistant allows you to use GitHub Copilot for inline code completions, and Anthropic Claude for chat and agent mode. The documentation has instructions for getting this set up so I won’t go into those details. You make a configuration change in Positron, then sign into your GitHub account with OAuth, and put in your Anthropic API key, and you’re off to the races.
Code completion with GitHub Copilot
This isn’t anything new. GitHub Copilot has been available in VSCode and RStudio for years. But it’s nice to have it available in Positron now.
Here’s a demo where I’m starting with a blank R script, and write comments in the code describing what I want, then let Copilot take it away as I just hit the tab key to accept the suggestions. Here I’m asking for a function to reverse complement a DNA sequence. Here’s the code it produced.
Agent mode to create an R package
When Positron first came out I wrote about using it for R package development.
I wanted to try out Positron Assistant’s agent mode to see how it works with R packages. Cursor and Claude Code seem to be all the rage on all the tech podcasts, Twitter feeds, and blogs I follow, but I’ve been reluctant to switch IDEs (or in the case of Claude Code, ditching the IDE altogether).
I started up a fresh R session and ran usethis::create_package() to create a blank package. This just creates the bare minimum (DESCRIPTION, NAMESPACE, etc.) needed for a skeleton R package. Then I activated Positron Assistant in agent mode, asked it to write a function in the package to reverse complement a DNA sequence, document it with Roxygen, and write unit tests with testthat.
It’s fun to sit back and watch the agent work. It scans the directory structure, finds the R version, creates the function, writes the documentation, writes the tests, then presents a model asking me whether I want to run the tests that it just created. It wrote everything in one shot with all tests passing and no errors on devtools::check().
Everything you see here cost $0.09 cents using the Claude 4 Sonnet API.2
The one thing I had to fix was the License field in the DESCRIPTION file with a simple usethis::use_mit_license(). The default for this field came in from usethis::create_package() and was simply boilerplate telling me that I needed to choose a license. Once I fixed this all tests passed, and the package check came out clean with 0 errors, warnings, or notes. I uploaded the package here on GitHub.
It was honestly pretty mesmerizing to sit back and watch the agent do its thing, inspecting the environment, writing code, docs, and tests.
Obviously this was a simple greenfield example, and I’d be curious to see how the agent handles larger codebases with complex dependencies and newer coding paradigms (like R’s new S7 OOP system) that won’t have good training data from Stack Overflow or elsewhere.
At the time I’m writing this (July 2025) Positron Assistant is still in preview, meaning that features might change by the time you’re reading this. For instance, currently only GitHub Copilot is available for inline code completions, and only Anthropic Claude is available for chat and agent mode. I’m sure both of these will expand in the near future to allow for other model providers (although Claude 4 consistently ranks at the top for R coding capabilities).
So many people I’ve talked to have no issue paying $20/month for ChatGPT Plus or Claude Pro, but are reluctant to buy API credits. I’m not sure how to rationalize this. I think there might be a misunderstanding that it works like AWS, where you put in a credit card and could accidentally rack up a huge bill. It doesn’t work like this. It’s a prepaid service. I put $5 on my account months ago just to experiment around a bit and I still haven’t used it all. You can set rate limits and email notifications on your API keys if you’re worried about spending more than a few pennies trying out something like what you see in this post.