ruddr is a tool that lets your Codex or Claude Code spin up other instances of any model harness with any model, letting you set up model-agnostic workflows from any harness
write your code with Claude Code, have it reviewed by Codex, just tell your agent to use ruddr CLI
ruddr also has a pretty cool 'session viewer' for all your agents, (Factory Droid, Pi, Codex, Claude Code, OpenCode are all supported) so you can see all your sessions and their diffs and what changes were made all in one place LIVE! (EXTREMELY fast btw)
I was tired of opening my IDE to view session-specific git diffs, it is now way easier, I can ask Opus 5.5 to spin up a GPT-6.1 Sol subagent using ruddr to review it's work, and your agent can even steer the agents spun up by ruddr and look at their progress live and provide additional context at anytime, and so can you with the ruddr TUI at anytime, including a live diff for every session, using ruddr or not :D
Claude Opus 5.5 rewrote this entire project from Go + Bun to entirely in Rust in about 2 hours (besides the web dashboard which is TypeScript) with 5 subagents and one final review agent, before using ruddr itself to review it's work using GPT-6.1 Sol, below are the stats:
TUI memory: 119 MB → 7 MB
npm install: 512 MB, 174 packages → 18 MB, 1 package
runtime: needed Bun → none
binary: 6.5 MB → 18 MB (now includes the TUI, web dashboard, and agent adapters, MORE features than before)
holy shit "rewrite this in rust" worked