Show HN: Mysti – Claude, Codex, and Gemini debate your code, then synthesize

Posted by bahaAbunojaim 12/23/2025

Show HN: Mysti – Claude, Codex, and Gemini debate your code, then synthesize(github.com)

Hey HN! I'm Baha, creator of Mysti.

The problem: I pay for Claude Pro, ChatGPT Plus, and Gemini but only one could help at a time. On tricky architecture decisions, I wanted a second opinion.

The solution: Mysti lets you pick any two AI agents (Claude Code, Codex, Gemini) to collaborate. They each analyze your request, debate approaches, then synthesize the best solution.

Your prompt → Agent 1 analyzes → Agent 2 analyzes → Discussion → Synthesized solution

Why this matters: each model has different training and blind spots. Two perspectives catch edge cases one would miss. It's like pair programming with two senior devs who actually discuss before answering.

What you get: * Use your existing subscriptions (no new accounts, just your CLI tools) * 16 personas (Architect, Debugger, Security Expert, etc) * Full permission control from read-only to autonomous * Unified context when switching agents

Tech: TypeScript, VS Code Extension API, shells out to claude-code/codex-cli/gemini-cli

License: BSL 1.1, free for personal and educational use, converts to MIT in 2030 (would love input on this, does it make sense to just go MIT?)

GitHub: https://github.com/DeepMyst/Mysti

Would love feedback on the brainstorm mode. Is multi-agent collaboration actually useful or am I just solving my own niche problem?

216 points | 178 commentspage 2

MrDunham 12/27/2025|

Website link on Github points to https://deepmyst.com/

But actually hosted on https://www.deepmyst.com/ with no forwarding from the Apex domain to www so it looks like the website is down.

Otherwise excited to deep dive into this as this is a variant of how we do development and seems to work great when the AI fights each other.

csomar 12/27/2025||

It's a good thing (/s) that Chrome now hides that fact. So it looks like the same domain is down on one tab and working on the other.

blks 12/28/2025||

An agent didn’t do very good job

thomas_witt 12/27/2025||

Codex CLI can run as MCP server ootb which you can call directly from Claude code. Together with a prompt to ask codex for a second opinion, that works very well for me, especially in code reviews.

bahaAbunojaim 12/27/2025|

But then codex won't have the full context of your existing work and might need to go through its own exploratory path

Tarrosion 12/27/2025||

> Is multi-agent collaboration actually useful or am I just solving my own niche problem?

I often write with Claude, and at work we have Gemini code reviews on GitHub; definitely these two catch different things. I'd be excited to have them working together in parallel in a nice interface.

If our ops team gives this a thumbs-up security wise I'll be excited to try it out when back at work.

bahaAbunojaim 12/27/2025|

Would love to hear your feedback! Please let me know if I can make it any better or if there is anything that would make it very useful

tacone 12/27/2025||

Interesting, I was trying to implement this using AGENTS.md and the runSubagent tool in vscode. Vscode has not yet the capability to invoke different models as subagent so I plan to fallback to instructing copilot to use copilot-cli and gemini-cli. (I am quite angry about copilot CLI offering only full blown models and not the -mini versions though)

bahaAbunojaim 12/27/2025|

I'm planning to add copilot, cursor and cline but feel free to contribute to the repo if you would like to do that and will look for ways to use the mini versions of the models as well when I integrate copilot CLI

tacone 12/27/2025||

Problem is, Copilot CLI doesn't really supports free or mini models. You have very tight choice of models. This looks like product decision. I understand why they won't allow you to use the free models on CLI, but not being able to use the (pay for) mini models is beyond me.

bahaAbunojaim 12/28/2025||

copilot support was just added in version 0.2.2

bahaAbunojaim 12/28/2025||

UPDATE: Mysti 0.2.2 Release

Hey HN! Quick update on Mysti based on your feedback:

1- Mysti now supports GitHub Copilot CLI as a fourth provider. So you can now do Claude Code + Copilot (running GPT-5) in Brainstorm mode, or any combination of the 4 providers. Mix and match based on what catches different issues.

2- Mysti is now MIT Licensed. Switched from BSL 1.1 to MIT. 3- Better Auth UX When a CLI isn't authenticated, you now get a friendly error with one-click "Open Terminal & Authenticate" instead of cryptic CLI errors.

danielfalbo 12/27/2025||

How do we measure this is any better than just using 1 good model?

bandrami 12/27/2025||

One day someone will actually build something with an LLM and do a write-up of it, but until then we'll just keep reading about tooling.

Closi 12/27/2025||

Anecdotal experience, but when bugfixing I personally find if a model introduces a bug, it has a hard time spotting and fixing it, but when you give the code to another model it can instantly spot it (even if it's a weaker model overall).

So I can well imagine that this sort of approach could work very well, although agree with your sentiment that measurement would be good.

danr4 12/27/2025||

licensing with BSL when basically every month the AI world is changing is not a smart decision.

bahaAbunojaim 12/27/2025||

Thinking of switching to MIT, what do you think? Is there any other license you would recommend ?

RobotToaster 12/27/2025||

AGPL, it requires anyone who creates a derivative to publish the code of said derivative.

bahaAbunojaim 12/27/2025||

Good idea! Very good point

rynn 12/27/2025|||

> licensing with BSL when basically every month the AI world is changing is not a smart decision

This turned me off as well. Especially with no published pricing and a link to a site that is not about this product.

At minimum, publish pricing.

bahaAbunojaim 12/27/2025|||

Regarding DeepMyst. In the future will offer “optionally” the ability to use smart context where the context will be automatically optimized such that you won’t hit the context window limit “ basically no need for compact” and you would get much higher usage limits because the number of tokens needed will be reduced by up to 80% so you would be able to achieve with a 20 USD claude plan the same as the Pro plan

tacone 12/27/2025||

I strongly suggest to also allow to define a non summarizable part of the context so that behavioral rules stay sharp.

bahaAbunojaim 12/27/2025||

I agree and this is part of what DeepMyst is capable of doing

tacone 12/27/2025||

Is it already there? Pretty cool.

bahaAbunojaim 12/27/2025|||

It is free and open source. Will make it MIT

bahaAbunojaim 12/27/2025||

Done and converted to MIT

rynn 12/27/2025||

Awesome, in that case, I'll check it out!

bahaAbunojaim 12/27/2025||

The project is now MIT!

deepsummer 12/27/2025||

Great idea. Whether brainstorm mode is actually useful is hard to say without trying it out, but it sounds like an interesting approach. Maybe it would be a good idea to try running a SWE benchmark with it.

Personally, I wouldn't use the personas. Some people like to try out different modes and slash commands and whatnot - but I am quite happy using the defaults and would rather (let it) write more code than tinker with settings or personas.

bahaAbunojaim 12/27/2025|

Fair enough on personas, I like to activate skills more than personas, for example I activate the auto commit skill to ensure the agent would automatically commit after finishing a feature

scrame 12/28/2025||

> Mysti — Built by DeepMyst Inc

links to: https://deepmyst.com/ Site 404's.

> Made with Mysti

Ringing endorsement.

bahaAbunojaim 12/28/2025|

Link fixed

DenisM 12/27/2025|

Multi agent collaboration is quite likely the future. All agents have blind spots, collaboration is how they are offset.

You may want to study [1] - this is the latest thinking on agent collaboration from Google.

[1] https://www.linkedin.com/posts/shubhamsaboo_we-just-ran-the-...

NitpickLawyer 12/27/2025||

> Multi agent collaboration is quite likely the future

Autogen from ms was an early attempt at this, and it was fun to play with it, but too early (the models themselves kinda crapped out after a few convos). This would work much better today with how long agents can stay on track.

There was also a finding earlier this year, I believe from the swe-bench guys (or hf?), where they saw better scores with alternating between gpt5/sonnet4 after each call during an execution flow. The scores of alternating between them were higher than any of them individually. Found that interesting at the time.

paulirish 12/28/2025||

The latter, if any else are curious: https://www.swebench.com/post-250820-mini-roulette.html

bahaAbunojaim 12/27/2025||

Thank you so much for sharing Denis! I definitely believe in the that as the world start switching from single agent to agentic teams where each agent does have specific capabilities. do you know of any benchmarks that covers collaborative agents ?

DenisM 12/28/2025||

You’re welcome.

I don’t know if benchmarks, sorry.

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