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B

btw

AI-ASSISTANTS
Velocity2.5

A Toolkit for Connecting R and Large Language Models

github.com/posit-dev/btw ↗

btw is turning into an agentic R harness that no longer needs you to be in R

llm toolingragentic workflowsdeveloper toolsskillsposit
◆Current state
btw assembles context about an R session — packages, documentation, files, data frames — and hands it to an LLM through ellmer, with btw_app() as a chat interface. Over the last year it has grown well past context assembly: LLMs can document, check, test and measure coverage of a package, read CLAUDE.md and AGENTS.md as project context, fetch skills from packages or GitHub, and inspect the source of any installed namespace. Much of this is now reachable from a terminal CLI rather than only from an R prompt.
◆Where it's heading
The direction is from describing a session to operating on it, and from inside R to outside it. Each release adds either a tool group that lets a model do something (document, check, test, cover; read namespace source; fetch skill resources) or a CLI command that removes the need to start R first. The 1.2.0 tool renaming — session becoming sessioninfo, search becoming cran, files_read_text_file becoming files_read — reads as the naming cleanup you do when you expect a lot more tools to follow.
◆Prediction
The CLI has been absorbing one tool family per release (skills, then pkg desc and pkg src) while the R-side tool groups stay ahead of it, so the next releases likely continue exposing existing tool groups as terminal commands rather than adding new capabilities.

◆Recent moves

  1. 10d ago

    btw 1.4.0 adds CLI commands for reading R package source

    The CLI direction set in 1.3.0 extended to code inspection: btw pkg src can list objects, get exact source or deparsed functions, inspect package-owned S3 and S4 methods, locate installations and search implementations, while btw pkg desc surfaces DESCRIPTION metadata. btw_app() also stops accepting model, prompt or tool changes mid-stream and keeps tool selection synchronized across model switches.

    View source ↗
  2. 1mo ago

    btw 1.3.0 makes skills fetchable from the terminal

    ⚡ SPARK

    The release that takes btw outside R. Three CLI commands discover and fetch skills from packages or GitHub repositories without an R session, and btw_app() gains provider switching that carries chat history, system prompt and tools across the change.

    View source ↗
  3. 4mo ago

    btw 1.2.1

    Config locations made consistent across skills, agents and btw.md discovery, with 1.2.0-installed skills still found for compatibility, plus base packages declared in the CLI launcher frontmatter. Cleanup after the previous release's reorganization.

    View source ↗
  4. 5mo ago

    btw 1.2.0 renames its tool groups ahead of expansion

    A breaking rename pass with deprecation warnings rather than removals: the session group becomes sessioninfo, search becomes cran, and the files tools shed their _text_file suffixes. Unglamorous, but this is the naming discipline a package adopts when it expects the tool list to keep growing — which it has, every release since.

    View source ↗
  5. 7mo ago

    btw 1.1.0 lets an LLM document, check and test an R package

    ⚡ SPARK

    The release where btw stops only describing the session and starts acting on it. A new pkg tool group gives models the ability to run package development workflows directly, and CLAUDE.md joins AGENTS.md as a recognised project context file.

    View source ↗