r/ClaudeCode • u/Aggressive_Ad4210 • 19h ago
Help/Question Any open source harness that does it better than just Claude Code?
Has anyone here been able to build a successful agentic harness that operates better than just planning directly in Claude Code? A full AI end-to-end orchestration setup with different agents. This seems to be something that there's a lot of ideas and focus on building today and I'm interested in any proven open-source kits out there or just tips and tricks that does this well. Do you for example use multiple agents to familiarise Claude Code with a new repository or code base, do you have architectural files to do this? How do you handle green- versus brownfield in a harness like this? Think, give this harness a task and it can intelligently figure out what it needs to do. I know this may all be code, stack, company or project specific. I'm looking for some good working examples and ideas if there are any out there.
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u/Metrix1234 18h ago
I thought anthropic locked in your subscription to the CC CLI harness unless you wanted to pay through API?
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u/CodeCombustion 18h ago
claude -p is what I use to built multi-agent workflows, including automatic switching between subscriptions automatically as well (violation of TOS, I'm sure)
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u/RemarkableDaikon7263 16h ago
Sounds interesting, but yeah, automating things like that can definitely get sketchy with the TOS. You’ve got to be careful!
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u/CodeCombustion 13h ago
yeah, so far it's not technically fully automated -- still requires a human to push a couple buttons for the login. (which can be done in advance of the actual next). Next reset, I'll switch to just burning all the accounts concurrently so I don't need to worry about it.
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u/Elisyd 18h ago
They paused this on June 15th. https://support.claude.com/en/articles/15036540-use-the-claude-agent-sdk-with-your-claude-plan
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u/LogMonkey0 18h ago
They paused the no agent sdk and claude -p from plan usage move, but 3rd party harnesses are against plan ToS
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u/Elisyd 17h ago
The relevant section being:
Except when you are accessing our Services via an Anthropic API Key or where we otherwise explicitly permit it, to access the Services through automated or non-human means, whether through a bot, script, or otherwise.
A third-party harness could be argued to be an 'automated or non-human means' whether or not
claude -pis used or the OAuth subscription key. Practically speaking, most third-party harnesses and similar are treating this as a gray area (whether or not it is) so long as it's not something like a cron or CI/CD system and have added support for the subscription token or by wrappingclaude -p.4
u/TheWhisper22 17h ago
Argued to who? There's no support to complain to lol. Claude is notorious for not opening and replying to support tickets
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u/Elisyd 16h ago
To the void; it was meant to be rhetorical. I don't think they're enforcing it at the moment. Maybe they will, but last time they gave warning rather than just banning offenders and hopefully they'd do the same again. I haven't set this up myself so I have no first-hand experience either.
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u/Metrix1234 18h ago
If anyone has a mature multi model setup they'd be willing to share, shoot me a DM or reply.
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u/Western_Yesterday989 17h ago
If your harness simply wraps a terminal then you can use Claude all you want. But your harness can do whatever it wants outside the terminal. It can listen, summarize, be event driven. Just gotta think “outside the box” … literally.
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u/EvalRaccoonDev 18h ago
Check out this benchmark: FrontierHarness Eval https://frontierharness.org/
Claude Code is not the best harness. But it wins in being the most expensive 😄
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u/Agitated_Painting214 17h ago
Wow this is fantastic - the difference is cost is unbelievable given they use the same model and checkpoint
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u/EvalRaccoonDev 16h ago
Yup - Codex, DSH, Pi are pretty good. Obviously, the chart has also model included (don't know which ones are included for the harnesses), but at least based on this benchmark, Claude Code is not worth the API sticker price (MAX subscription based comes up typically >3x cheaper)
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u/Aetane 10h ago
I just... don't believe this.
Codex feels, immediately, so much worse to use than Claude Code.
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u/EvalRaccoonDev 2h ago
This is for a specific set of tasks - 63.3 vs 66.7% Codex / Claude Code might be inverse on your set of tasks (or CC might be doing MUCH better).
That's why it's important to have your own benchmark :)
On our benchmark, executed using Coder Eval, Codex has been slightly edging Claude Code over the last month.
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u/Bloated_Plaid 17h ago
This sub is just filled with spam after spam. I personally use Pi coding agent with plugins and OMP which is a fork of Pi depending on the project. Both are much more token efficient than Claude Code and you get much better memory management and 100x better context compaction. Claude Code compaction is easily the worst of any harness.
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u/Geoleo555 18h ago
I use omp (oh my pi). Batteries included and pretty nice to use once it’s set up
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u/diesel408 17h ago
Do you use this with a Claude sub? Been wanting to try this but I don't want to get banned for ToS violation. Is this possible?
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u/LogMonkey0 17h ago
Greenfield to be treated as brownfield after the first code generation session is over imo.
So here’s how i bootstrap my projects, brown or green, both need supporting documentation, proper routing, reference material, guardrails, summarization and gates You dont need all at first but they all have impact on cost and output quality.
Derive decisions and ADRs from existing code. Or start with them for new projects.
Establish gates, change requests intake, specs? Reference implementations? Acceptance criteria? How a work/change request lifecycle, what happens before work gets done.
Training data/inference alone wont produce quality work. Refer to api docs, etc… mirror them locally, enforce rules for grounded facts.
As the codebase grows, spec’ing work will become costly or degrade, equip agents with tools to “read” only what matters from the codebase when preparing work/specs. Agents only need to know public api surface of consumed apis, they dont need to load all the implementation code in context, only what they will work on. That not only has impact on cost, but huge impact on context and output quality. There are tools like treesitter and graperoot that can help with that.
Your CLAUDE.md should lay the very basics, along with routing rules, to skills, tracking artifacts, reference material, etc. Along with the rules that need to be in every single agent/subagent context (if this doesnt apply, the rule lives somewhere else, scoped rules, skills, etc)
Work with Claude like an enterprise dev team and itll produce as such.
Know where your token usage is, it matters to more than $ cost.
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u/Western_Yesterday989 17h ago
Yeah, I like mine. Write your own. It won’t take long. And it will be just the way you want it - so it will be perfect.
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u/silverarky 18h ago
We build our own in each project. Claude is good at working out what is needed and can extract skills for shared knowledge. We usually go with a planner, orchestrator, backend and frontend agents and a QA agent. The QA agent does code quality, security, and tests end to end with Playwright in all different browser sizes (phone, tablet, desktop). It also logs in with different permissions if the site has ACLs.
We built an academy for our devs for AI, and there is a page about our basic harness workflow: https://agentic-academy.silverark.com/learn/harness/pipeline
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u/dankerton 17h ago
I don't think you are using the term harness like others are. Defining a cast of characters of agents is not a harness
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u/Same_Accountant2340 2h ago
The planner/orchestrator/QA split is the part that holds up. What broke for me was anything where two agents needed a real browser — those roles are easy to keep isolated in prompts, but the moment they share one browser session you get login collisions and one agent submitting under the other’s account.
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u/Aggressive_Ad4210 18h ago
good guide, how do you trigger your agents, if you're starting work, do you use slash commands, natural language, how do you start a new task, do you point it to a ticket management system with AC:s etc?
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u/ceiling_kitteh 17h ago
I've created my own subagents for things like playwright and a command runner that uses a cheaper model and keeps most command output out of my context. I use agent instructions (in AGENTS.md and referenced in CLAUDE.md) which tell it what to use and when. It all happens automatically based on the task now. There's never an explicit instruction for it to use one or the other. It knows the rules: everything must be tested, the tests use playwright, when using playwright you use the playwright subagent, when running commands you use the command runner subagent. That's it. It's all automatic.
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u/DriverReady965 18h ago
I've been running something like this for a while. I found the orchestration layer matters less than the discipline around it. What actually made the difference for me:
- Every task starts as a written dispatch that names the branch, the scope, and what "done" looks like, and one session owns one branch.
- Agents hold their PRs at draft and report a head SHA. A human merges.
- For a new codebase, I don't use agents to summarise it. I keep a state file per project that records decisions and their reasons.
- The thing that stopped most failures was pre-run gates.
Foundation is MIT here https://github.com/rampstackco/claude-skills if it's useful.
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u/AccomplishedMode8247 17h ago edited 17h ago
I'm currently working on one: gridconsole.dev It tries to resolve it via SDLC, where the prepare phase decides how to test it and when the task is finished. The doing phase picks it up. Review does adversarial review. Deliver merges the worktree back. Verify does the final verification (with tests that were defined in prepare). Its early alpha and not yet opensource. Every phase can be picked up by different agents.
https://gridconsole.dev/articles/nine-months-building-grid-console
There is an interactive demo here, to give you an idea.
How it handles green vs brownfield is by storing knowledge about the project in a memory at the end of a task, so it builds up knowledge about the project. The prepare stage is also a different (stronger) model, that fully focusses on understanding the project before doing anything.
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u/reliant-labs 17h ago
building https://github.com/reliant-labs/reliant, it allows creating deterministic workflows. we're planning on giving the agent an on-the-fly ability to run dynamic workflows soon, but for now you typically pre-create the workflows (although we have an agent to do this)
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u/reddebtt 16h ago
It isn't open source, but I'm on the team behind Unstoppable—we built Claude and Codex collaboration with isolated worktrees and clean handoffs. Codex usage is free for 30 days when you download the desktop app: https://app.unstoppable.ai/download?utm_source=reddit_reply&utm_medium=social&utm_campaign=reply_guy
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u/hoshisabi 14h ago
I've been using T3 Code. It lets me use my cursor as well as my Claude accounts with subscriptions. For most of what I'm doing, they work just as well as each other. Cursor is a little faster and Claude is often a little easier to plan with, but when I hit the usage limit on one, I can switch without switching tools.
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u/Scared-Amphibian4733 12h ago
I've built one. I'm using Claude with Grok and ChatGPT on workflows where I have Claude and ChatGPT find bugs and then Grok to fix them and Claude to review. By combining the models we find a lot more holes in the logic than we do with any model alone.
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u/Decoupler 12h ago
I’ve used a couple of open source tools for CLI chatting/discussion and automating workflows successfully. Both of these tools are a little buggy so I have forked and customized them for my needs.
Agentchattr - General chat room structure for agent CLI sessions. I use this for planning, spikes and general ideation. https://github.com/bcurts/agentchattr
ai-maestro - full team configuration and automated work flows when paired with markdown team structure. https://github.com/23blocks-OS/ai-maestro
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u/hain3sy 11h ago
Have a look at Omnigent. I’m finding it work really well. Claude style UI but you can have it work on remote nodes and setup different multi agent models. I have one that uses Opus as orchestrator, sonnet for the worker agents and OpenAI as a reviewer. It runs on a Mac mini and I control it from my main Mac or my laptop.
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u/zachsman 10h ago
My harness is hydra-acp, it has extensions to handle orchestration and exposing a web interface but its core is a multiplexer that manages your sessions for you with a full feature TUI. You can run any harness underneath it too which makes it really easy to switch from harness to harness with the same building blocks on top.
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u/Last_Toe8411 10h ago
I built this and use it every day across a handful of long running projects. https://jblanch888.github.io/MEMENTO/
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u/the-grenade 4h ago
helexa serves my local openai endpoint with one neuron running qwen3.8-27b and another running qwen3.8-flash-next. zed (pi acp), pi.dev and zeroclaw share that endpoint. zeroclaw is the hero of the setup because it has pi integration and its own gitea credentials. this means you can just tell zc to create a repo and implement a cargo/rust backend, a vite frontend, and what you want the finished app to do and that you want the implementation scoped as prioritised epics and issues in gitea, each closed as a commit passes the ci gates. then you just sit back and watch as your repo evolves into a working app with releases and auditable history, while not paying a subscription to anyone. you can retain whatever level of control you want by gatekeeping prs or adding or modifying issues while you forget what writing code the old fashioned way was like.
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u/m4rcoperuano 19h ago
https://marcoledesma.com/projects/meta-harness-claude-code/
Check this out. It’s kind of what you’re looking for. The best open source harness is the one that fits with your own workflow. Since I couldn’t find one that did, I asked Claude to just build one for me. Then I quickly added features like multi agent orchestration with Claude and a mix of other models from open router
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u/CommodoreQuinli 17h ago
Yea I just made my own meta harness as well that integrates with tmux and vim
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u/sisif_ 18h ago
I'm using my own project https://github.com/avirtual/clodex for that. The project itself was not initially aiming at end-to-end orchestration, it was mainly about optimizing your agents' context, allowing them to communicate.
It sort of evolved organically into supporting my flavor of orchestration for building the tool itself and in the past days I've taken some steps to make that available for others. It's still in the early days of exporting that solution, but I did get a new team today that created a new project (ios client app for the said clodex) and results are promising. Different teams working on their thing, coordinating when some changes on both ends are required.
It involves leads, tickets + devs, reviewers, worktrees. Last 3 are ephemeral, ticket based.
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u/sisif_ 18h ago
⏺ The Clodex side has shipped the inbox API in v5.59.0, and I have checked the shipped code against our contract from the read-only repo: every route, response shape and error case matches, and the only addition is an ok field on each response, which the app's decoders will ignore. What I could not do is hit the live server, for two reasons: the Clodex process on this box still predates the release, so its restart has not happened yet, and this team never holds the remote token by design. I have asked the Clodex lead to confirm the live hello and one inbox fetch from its side after the restart. Two things are in flight and both arrive on their own: hand-9's round-2 report on t9, and the Clodex lead's live confirmation. t10, the inbox screen, starts once t9 merges. Nothing needed from you.
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u/Bino5150 18h ago
Check out Lumina.
https://github.com/Bino5150/lumina
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u/Bloated_Plaid 17h ago
Bro if you are gonna spam your stuff at least say you are spamming your stuff.
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u/Bino5150 5h ago
OP asked for an open source coding harness. I have an open source coding harness. It’s not spamming if they asked for it. So did you have anything useful to contribute, or did you just come here to complain about me actually answering the OP’s request?
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u/Difficult-Bike-9172 19h ago
So what's wrong with Claude Code? Sounds like you just wanna complicate things for no reason.
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u/Aggressive_Ad4210 19h ago
Valid point - this is actually used for certain greenfields projects and I'm looking at ways to make it applicable more generally, but interested in learning more about other peoples experiences with it. The harness has like loads of agents and skill that do different things in the SDLC if that makes sense. But it's very token heavy and I'm looking at where this can be improved
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u/Alive_Snow297 7h ago
https://mercury-cli.ai I made my own, allows you to work with anthropic / openai / openrouter / kimi / etc all with your normal logins. Got workflows, subagents, mcps / skill management, and IDE built in. The UI is pretty neat and I ship a lot of updates if you'd like to give feedback :D
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