Mirasim: one window for every coding agent

Anyone running Claude Code and Codex at the same time knows the drill: one terminal or client per tool, models locked to each subscription, and a window shuffle every time you switch projects. Mirasim (mirasim.ai) folds all of that into a single desktop IDE — the site’s own line is “any model, any harness, any mix of tools, skills and plugins — all in one window,” with multiple projects and sessions running in parallel, each carrying its own agent and model.

Core Purpose

Mirasim walks the same road as schedulers like Paseo — one surface for many coding agents — then goes three steps further. Sessions aren’t just monitored; each one gets a full workbench. Conversations carry forward between supported agents, so switching tools doesn’t mean re-explaining the task. And the TUI and GUI are one switch apart, so terminal people don’t get trapped in a graphical interface.

Onboarding is the smooth part: the quickstart requires exactly one of Claude Code or Codex, and existing sign-ins for either carry over as-is (an agent you haven’t installed can be set up by Mirasim’s Agent Config); there’s also a built-in Mirasim agent. Every session picks its own model and reasoning effort from a picker split into Native (subscription models) and My Models (your own model profiles) — pointing a session at a DeepSeek-class model works through your own configuration. A VS Code-style editor sits inside the window, sessions can run on a provisioned cloud machine, and a phone app picks them up on the go.

Key Scenarios

1. Multi-subscription power users: keep Claude Code, Codex and Chinese models side by side, and allocate quota from one workbench instead of installing yet another client to try a model.
2. Parallel projects: five or six repos with their task lists side by side, each session moving on its own without fighting over a terminal.
3. GUI and terminal, mixed: watch the task board in the GUI by day, flip to the TUI when you want it — config and sessions stay in one place.

Trying it and its limits

Grab a build at mirasim.ai/download — native on macOS (signed and notarized), Windows and Linux, plus a phone companion — sign in with your own accounts and start free. Paid tiers run Go $16/mo, Basic $29/mo, Pro $169/mo and Max $299/mo (per the site, checked September 30). Basic’s pitch is replacing a Claude Code Pro plus Codex Plus pair; quota is quoted as estimated requests per 5-hour window (Go: roughly 130 on Kimi K3); inviting three friends gets them a discount and you a month of Go.

The honest catches: the app itself shows v0.0.142 — very early software, so stability and long-term direction are open questions; Basic and above are essentially other companies’ subscriptions bundled into one quota, which adds a dependency on Mirasim between you and the labs — the site’s math isn’t a vendor guarantee; the “used by NVIDIA, Google, Meta” logo wall is unverifiable, so don’t factor it in; and the free tier rides on your own model accounts, so model quality and limits remain whoever’s you use.