I've been using multiple AI coding agents in parallel, usually in separate Git worktrees. The problem wasn't getting agents to work simultaneously. It was merging everything afterward. Each agent would finish its task, but once I combined their changes, something would break. Then I'd have to figure out which change caused it, send the errors back to an agent, wait for another fix, and run the tests again. It was wasting time and tokens, especially when several sessions were working on the same codebase. So I started building Fanout, an open-source tool for coordinating parallel Claude Code and Codex sessions. A few things it does: Detects when two sessions are attempting the same task, even if the requests are worded differently. Notifies a session when another agent commits changes to files it has been working with. Detects overlapping changes across Git worktrees. For planned parallel jobs, tests the combined branches before merging and sends integration failures back to the responsible agent. It works alongside existing coding agents. You don't have to replace Claude Code or Codex with another agent framework. It's still early, and it doesn't guarantee conflict-free or bug-free code. I've tested it on my own workflows and built automated tests, but I'm looking for independent users to find the problems I haven't encountered. It's free, MIT-licensed, and has no external runtime dependencies. GitHub (including a demo and installation instructions): https://github.com/Breadstick-Crumbs/fanout I'd especially like feedback from developers already using multiple Claude Code or Codex sessions. Does the integration/merge problem happen in your workflow too? And if you try Fanout, what would stop you from keeping it installed? Honest criticism is welcome.   submitted by   /u/crumb_ona_breadstick [link]   [comments]