Manaflow bets the terminal, not the IDE, wins the AI-agent era; cmux 21.6K stars

Manaflow builds cmux, an open-source, macOS-native terminal (Swift/AppKit on Ghostty's libghostty) with vertical tabs, notification rings, an embedded scriptable browser, and a socket API, purpose-built for running fleets of AI coding agents (Claude Code, Codex, Gemini CLI, and more) in parallel.

The future is IDE-less: devs running 5–10 AI agents need a native, programmable terminal primitive, not a GUI orchestrator — cmux becomes the default place agents work.

$500K standard YC seed (S24) per ROSS Index and the YC company page; no other disclosed funding as of mid-2026.

Austin Wang and Lawrence Chen, accepted into Y Combinator's Summer 2024 batch, first built Manaflow as an applied-AI lab for enterprise workflows, then pivoted to developer tools after concluding the IDE era was ending. cmux launched Feb 2026, peaked at #2 on Hacker News, and grew from zero to 3.5k GitHub stars in two weeks.

By June 2026 cmux had 45+ releases and ~21,600 GitHub stars in about four months; ROSS Index Q2 2026 recorded 23.2K stars at end of Q2 (17.6x growth) and YC's $500K backing. The YC company page reports builders from Nvidia, Google, and OpenAI using it, plus shout-outs from Mitchell Hashimoto (Ghostty creator) and Nick Schrock.

Still running: cmux remains free and open source (GPL-3.0-or-later) with a commercial-license path and a 'Founders Edition' offering early access to AI features, an iOS app, and Cloud VMs; the company is still a two-founder operation with no new disclosed round.

The bet rode a real workflow shift: engineers running 5–10 agents in parallel had no good local tool — tmux lacked agent awareness and GUI orchestrators locked users in.

The founders bet on the terminal over the IDE, pointing to figures like Claude Code's creator not opening an IDE since late 2024, making cmux a bet on where coding happens next.

Open-source distribution was the moat: a free GPL binary, one-command Homebrew install, and Ghostty config compatibility removed switching cost, and the #2 HN launch seeded the star curve.

The unopinionated 'primitive' stance kept users building on cmux instead of waiting for features, compounding community investment.

Sell a primitive, not a solution: cmux stayed unopinionated and gave developers composable pieces, so the community built the workflows while the founders kept monetization optional.

As of 2026-06-10 cmux is live and free: ~21,600 GitHub stars in four months, 45+ releases, and builders from Nvidia, Google, and OpenAI reported by the YC page. Manaflow (YC S24) still has no disclosed round beyond the $500K YC seed and remains a two-founder operation; monetization is optional — GPL with commercial licenses, plus a 'Founders Edition' selling early access to AI features, an iOS app, and Cloud VMs. The bet is unresolved: whether a terminal primitive becomes the default place agents work, and whether Manaflow converts its community into revenue before rivals close the gap.