Show HN: Gigacode – Use OpenCode's UI with Claude Code/Codex/Amp
github.comGigacode is an experimental, just-for-fun project that makes OpenCode's TUI + web + SDK work with Claude Code, Codex, and Amp.
It's not a fork of OpenCode. Instead, it implements the OpenCode protocol and just runs `opencode attach` to the server that converts API calls to the underlying agents.
We build this to scratch our itch of being able to rapidly switch between coding agents based on the task at hand. For example, we find that:
- Claude Code is the best executor & fast iterator - Codex (high) is the best for complex or long-running tasks - OpenCode for fine-tuned, do-exactly-as-I-say edits
I personally believe that harnesses matter almost as much as the models in 2026. OpenCode lets you swap out models already, but the CC & Codex harnesses + system prompts make a big difference in practice.
Under the hood, this is all powered by our Sandbox Agent SDK:
- Sandbox Agent SDK provides a universal HTTP API for controlling Claude Code, Codex, and Amp - Sandbox Agent SDK exposes an OpenCode-compatible endpoint so OpenCode can talk to any agent - OpenCode connects to Sandbox Agent SDK via attach
I want to emphasize: the Anomaly folks are doing awesome work with OpenCode agent + Zen + Black. I use OC regularly alongside CC & Codex depending on the task. Gigacode is only possible because OpenCode is insanely flexible, hackable, and well documented.
Give it a try:
$ curl -fsSL https://releases.rivet.dev/sandbox-agent/latest/gigacode-ins... | sh
Check out the project, architecture, and other install options:
https://github.com/rivet-dev/sandbox-agent/tree/main/gigacod... I feel like this was made for me. I really like the OpenCode UI. Maybe this will finally create an ecosystem interchangeable LLM backends and UIs. I hope this will go beyond just coding agents. Been using it for a bit now, it's very convenient if I may say so myself. We're shipping a big stability update in a few minutes – would love feedback! Doubtful, AI cloud needs to lock in users. There's no world where they justify their values and say "the user can switch at any time" That's why I choose to distance myself from those vendors and products :) The interesting stuff is happening in (free and) open source software. This looks neat. Thank you! How does this relate to the recent changes of not being able to use a Claude Code Max subscription outside of Claude Code anymore? I assume technically this would work with Gigacode but would still be against their ToS? > I personally believe that harnesses matter almost as much as the models in 2026. Agreed. Great work Thanks! Spontaneously I would like a protocol between agents and the clients and that's exactly what agentclientprotocol.com is. I wonder if you shuffle acp over https is it then similar to sandbox api used here? Yes. We want to support ACP. They have a spec for HTTP transport in the works, but there is nothing public on it. Trying to backchannel to the right folks. What's the benefit of using opencode ui vs vscode with agents? OpenCode supports: - TUI (I prefer this for most programming) - Web UI (negligible difference than VS Code) - Mobile support (via web UI) - TypeScript SDK to automate