rum

a coding agent you can watch think. built in rust.

brew install KAJdev/rum/rum

why rum?

rum fuses a coding agent and a code editor into one terminal. one view is the agent chat feed. the other is a full editor with syntax highlighting, LSP, and fuzzy search. follow mode links them: as the agent reads and edits files, the editor tracks every operation in real time, jumping to each change with inline diffs. a sidebar on the editor shows agent progress without switching views.

you watch the agent work the way you'd watch a coworker's screen. except you can take the keyboard at any time.

install

# homebrew

brew install KAJdev/rum/rum


# pre-built binary

cargo binstall rum


# from source

cargo install --path .

getting started

run rum in any project directory. first launch opens your browser to log in with Anthropic. you can also set ANTHROPIC_API_KEY if you prefer.

rum

rum "add error handling to the api routes"

rum -p "explain this codebase"

rum --model opus --thinking high "refactor the auth module"

follow mode

Ctrl+F. the core of rum.

every file the agent touches is tracked. the editor opens each one automatically, jumps to the relevant section, and marks changes with inline diff markers. Alt+Up/Down walks the full history of file operations.

editor

Ctrl+E switches between chat and editor. syntax highlighting, undo/redo, mouse support. Ctrl+P for fuzzy file search, Ctrl+/ for project-wide text search, Ctrl+G for go-to-definition.

LSP starts automatically for rust, typescript, python, go, and c/c++. if a server isn't installed, rum downloads it.

tools

the agent can read, edit, write, and search files. run shell commands (foreground or background). search the web. view images. spawn read-only sub-agents for deep investigation. query LSP for definitions and diagnostics. tools run in parallel when possible.

sessions

conversations persist per-directory and restore on restart. /compact summarizes long conversations to free context. /tree opens a conversation branch navigator for forking and exploring different approaches.

context

rum loads AGENTS.md and CLAUDE.md from every directory between the filesystem root and your cwd, plus ~/.config/rum/, ~/.pi/agent/, and ~/.claude/. custom system prompts via SYSTEM.md. settings merge from config files.

print mode

rum -p streams to stdout without the TUI. tool calls and thinking go to stderr. summary with tokens, cost, and timing at the end. useful for scripts and CI.

license

MIT