Show HN: Juggler – an open-source GUI coding agent, by the creator of JUCE

Show HN: Juggler – an open-source GUI coding agent, by the creator of JUCE(github.com)

71 points by julesrms 1 day ago | 38 comments

Hello HN, I don't post on here much, but wanted to get some eyes on a new project I'm just launching. I think we definitely need one more AI code agent..

I'm a long-term C++ dev, and over 30+ years I've created some successful audio dev tools (JUCE, the Tracktion DAW, the Cmajor DSP language). All of these came from me getting annoyed with something I had to use, and deciding to have a go at my own take on whatever it was.

So Juggler is my attempt at an AI code agent, after spending too many hours loving what the models could do, but hating the CLI experience, and having some opinions of what a better UX might be for this stuff.

Lots more blurb on the website and github, but a quick tech dump which might grab your attention if you're into these things:

A session is a document, not a log file. Each conversation is a Yjs CRDT tree. It can branch into sub-threads (recursively), and you can drill down, backtrack, edit, undo/redo, and inspect everything: tool calls, approvals, and the raw context JSON going to the model, etc. The UI is based around Finder-style Miller columns rather than a big doom-scroll, and is quick to navigate.

Because it's a CRDT behind a local web server, multiple clients can attach P2P to a live session: the native desktop app, a browser tab, or your phone. Run the headless server on the box where the code lives, view it from wherever.

Almost everything is a JavaScript plugin: every item in the context (read/write/bash/etc.), the LLM loop strategies, slash commands, and their UIs. You can inspect, fork, or replace any of them. I don't do much agent customisation myself, but lots of people do, and I'd love to see what they think of with this plugin API.

Go backend, Wails for windowing (no Electron), plain type-checked JS (strict JSDoc), Yjs for the documents. Usual BYOK provider support: Claude (CLI or API), OpenAI/Codex, Gemini, Ollama, OpenRouter, DeepSeek, etc.

The app's AGPLv3; the extension SDK and bundled extensions are Apache-2.0, so extensions have no copyleft strings attached. No signup, no telemetry, trying to make it frictionless for people to try it out..

It's very much a beta, and is a one-man side project. It hasn't yet had a proper kicking from the real world, but I'm confident some people with similar preferences to my own will like it!

https://juggler.studio

robbomacrae 48 minutes ago |

This looks really interesting and a unique take on the AI agent orchestration. I think we need a bunch of experiments in this area as it's clear we are entering a new paradigm and the tools for it are lacking. The session tree in particular has merits.

I've got my own attempt with OrcaBot (short for orchestration of bots). It's also been a 6 month solo build experiment. I'm not trying to plug.. just that I'm also neck deep in Steve Yegge's Stage 8 AI-assisted coding chart and understand how much thought and effort went into this.

Thinking about where this is all going with talking to AI like fully autonomous employees similar to @Claude can you see a comms app type approach that combines something like slack with your tree/thread structure? It's somewhat orthogonal to your "inspect everything" but could intersect by bringing click through/open in options...

julesrms 43 minutes ago | |

TBH I'm not coming from the same angle as all the gas-town fever-dream agent swarming stuff. I'm much more on the hands-on coding side, I tend to do one thing at a time and still do the git commits myself. So that's the UX I'm dogfooding..

However I see all those people out there trying to build these huge agent orchestration schemes, and if juggler's extension system can do that (or could be made to do that with a few tweaks) I'd be really interested in helping that to happen

robbomacrae 34 minutes ago | | |

I think I'm more on your side on that rather than letting agents go wild like Steve Yegge/Pete Steinberger do. In fact OrcaBot quickly adapted into a knee jerk reaction to OpenClaw because I saw that as inherently dangerous.

But with regard to Juggler and orchestration, have you seen "claude agents" (started in the terminal as claude agents instead of just claude). I ask because your tree like approach has similarities to how claude agents manages claude agents/subagents doing tasks with the ability to drill down in to each at a time which is why for me its not such a leap from what you already have.

gnarlouse 42 minutes ago |

@julesrms thank you for lending more credibility to the idea that agent conversations need to be natively branching. It's crazy that we're almost 3 years in on this LLM joyride and we still don't have the ability to do, like, reddit/slack-style "aside" convo threads.

~~edit~~

wait, are you doing that? Love JUCE btw

paldepind2 4 minutes ago | |

Can you go more in depth on why LLM conversations should branch reddit-style? That doesn't seem immediately clear to me, and I'd be afraid that the different branches would step on each others toes? (also I'm assuming what you're describing here goes beyond the "fork" feature found in many agent harnesses).

julesrms 38 minutes ago | |

I know! But 3 years is a very short time for a whole new category of tools to find the best design. It's incredible how quickly a lot of the big agents were dragged into existence, I'm amazed they worked at all..

everforward 1 hour ago |

ACP support would be a big deal and would make this a real contender for me. It looks super nice, but the idea of re-writing my Pi plugins is a real blocker.

I’m generally happy with my agent and want to keep that, but I do think the UI could be better and this looks like a neat step that way.

jdright 32 minutes ago | |

Agreed, ACP should be a minimum requirement on new agentic tooling. Hope this gets it, then I can try using my niche agent.

julesrms 25 minutes ago | | |

Message received, I'll make ACP the top item on my TODO list!

julesrms 1 hour ago | |

Cheers, I'll put ACP on my list of things to investigate

ireadmevs 33 minutes ago | | |

I guess there are 2 sides of ACP that are valid then. What was asked is for Juggler to act as a ACP client. I, on the other hand, would appreciate it to be a ACP server, so that I can interact with it from my editor when I’m on my machine and from the web when on the go or for more advanced functionality. That’s my current approach with opencode.

Semkas 1 hour ago |

This looks cool! I'll check it out. Out of curiosity: I assume you've also used agents to help build this, and on the site you mention working on this for ~6 months. Most one-man projects I see that use ai seem to focus on creating and presenting a concept as soon as possible (to a lot of people I think the main benefit of stuff like vibing is that you really quickly get something that you can have others test out).

On the site you also mention being pretty opinionated about the tools you use / build, which I imagine is part of the reason why you spend more time on this before releasing it. What was your experience using ai to build a larger project with a very specific idea / taste in mind?

julesrms 1 hour ago | |

I must have authored literally a million lines of C++ over my career, and done many talks about clean coding, etc.. But in this one I quite appropriately wrong almost zero lines by hand!

Surprisingly, I've really enjoyed the experience. I have friends who lament that they probably won't be hand-writing code much more, but although I've always loved the craft of coding, I discovered that a lot of the fun I get is just in the end result, not how I got there.

SoleilAbsolu 1 hour ago |

Nothing to say regarding this release, but thanks so much for creating Tracktion (first DAW I ever used back in 2006) and JUCE (I love and use many audio plugins created with it)! Have a great day!

julesrms 1 hour ago | |

Thanks!

buggylearning 1 hour ago |

Could you include screenshots on your github page?

julesrms 1 hour ago | |

Ah, good idea, I should do that..

tomduncalf 45 minutes ago |

Hey Jules! This looks awesome, excited to check it out :) Hope you're doing well! Tom

julesrms 42 minutes ago | |

Oh, hi Tom! Hope you're doing well!

prabhanjana_c 2 hours ago |

UI is clean. could install in Mac. Adding context files at the top is clean. It worked. Currently I use zed, vscode (for UI). along with claude, codex, Hermes. Not sure If I will continue to use. But I see it is a clean and good UI, and integrating to my exiting cli's. All the best.

julesrms 2 hours ago | |

Thanks! I think hearing "the UI is clean" is exactly the reaction I've been hoping for :)

While I've put huge effort into things like its architecture and extension API, it's really trying to just build a lovely UI/UX that has been my motivation on this.

MomsAVoxell 1 hour ago | | |

Out of curiosity, did you use JUCE to build this? Were there any interesting gotcha's you encountered along the way?

I've settled on JUCE as my cross-platform app framework (not just plugins) of choice, so it'd be interesting to hear about your experience with building this app out .. could you tell us a bit more about the architecture and any impactful decisions you made along the way with regards to tooling/integration? Is there now a juce-go-module or something like that, which you've wired up to JUCE' web view functionality?

Shorel 1 hour ago |

Great work, it is very funny that I did just the opposite :)

Got fed up with Zed, Cursor, and the other GUI agentic tools and created a console TUI agent for my own use.

julesrms 1 hour ago | |

There's definitely the CLI and non-CLI camps!

But TBH I think a lot of the GUI agent tools so far have been pretty much terminal apps wrapped in a thin GUI layer, which is why they don't seem to add any value over just doing the same UX in a terminal

drcongo 45 minutes ago |

Having now given it a quick spin, I like the UI concept and could definitely see myself working with this. I ran into a bug(?) almost immediately though, I hooked up Deepseek 4 Pro, gave it a small task and got this

``` LLM error: POST "https://api.deepseek.com/v1/chat/completions": 400 Bad Request {"message":"The `reasoning_content` in the thinking mode must be passed back to the API.","type":"invalid_request_error","param":null,"code":"invalid_request_error"} ```

I'm unsure about putting my Anthropic key in there as I've lost track of what they ban you for or whether that eats money from outside of my subscription.

Oooh, and nicer support for codefences would be good.

julesrms 41 minutes ago | |

Ta for the heads-up, these provider API things are super easy to fix, but hard to keep on top of them changing under our feet!

drcongo 31 minutes ago | | |

No problem. A tiny bit more working with it and I think I'm sold, it fits my mental model really nicely, thanks!

LeSaucy 1 hour ago |

For running headless is it possible to not require installing libwebkitgtk-6.0.so.4

julesrms 1 hour ago | |

At the moment it uses a GTK webview for running server-side javascript, so it's needed right now. At some point I'll see if I can find a JS engine that I could swap in there

julesrms 3 hours ago |

Just wanted to add a follow-up to what I posted above..

In terms of who might be interested in this: I've watched amazing communities spring up around open agents like Opencode and Pi. People are getting into those because of their extensibility and being model-independant. They're great projects, but like many people I know, I really hate being stuck in the terminal for this kind of tool. I also had some ideas around what an agent's UX could be like if every item in the context was a plugin (with its own custom UI).

So I guess if you're a claude/codex user but want to escape the terminal (and let's face it, their GUI apps are also basically the same UX as a terminal but with nicer fonts), I'm trying to do something different here, would be really keen to hear what the enthusiasts think of it!

blackberrysoda 1 hour ago |

I thought "Wails" was gonna be short for "Wuby on Wails" lmao

Cool project actually, but I noticed the author said "No Electron" as if Electron is synonymous with JavaScript.

My biggest concern about it actually is using Go to render web front-ends in HTML/CSS hahah so I'm not sure "No electron" is selling me.

julesrms 1 hour ago | |

"No electron" is more about avoiding bloat and dependencies.

I come from a hardcore, real-time C++ background and the idea of a product not being a single self-contained binary is just too far for me to go!

(But I don't think the choice of JS back-end should make the slightest difference to anyone using this. I could swap electron in there in the future and probably no-one would notice)

drcongo 1 hour ago | | |

"no electron" sold it for me. I'll give this a go!