To me, the most interesting thing about Pi and the "claw" phenomenon is what it means for open source. It's becoming passé to ask for feature requests and even to submit PRs to open source repos. Instead of extensions you install, you download a skill file that tells a coding agent how to add a feature. The software stops being an artifact and starts being a living tool that isn't the same as anyone else's copy. I'm curious to see what tooling will emerge for collaborating with this new paradigm.
That's just because corporations got greedy and made their apps suck.
Strip away the ads, the data harvesting, add back the power features, and we'll be happy again. I'm more willing than ever to pay a one-time fee good software. I've started donating to all the free apps I use on a regular basis.
I don't want to own my own slop. That doesn't help me. Use your AI tools to build out the software if you want, but make sure it does a good job. Don't make me fiddle with indeterministic flavor-of-the-month AI gents.
I think there's room for both visions. Big Tech is generating more toxic sludge than ever, and yeah sure this is because they're greedy, but more precisely the root cause is how they lobbied Washington and our elected officials agreed to all kinds of pro-corporate, anti-human legislation. Like destroying our right to repair, like criminalizing "circumvention" measures in devices we own, like insane life-destroying penalties for copyright infringement, like looking the other way when Big Tech broke anti-trust laws, etc.
The Big Tech slop can only be fixed in one way, and actually it's really predictable and will work - we need to fix the laws so that they put the rights and flourishing of human beings first, not the rights and flourishing of Big Tech. We need to fix enforcement because there are so many times that these companies just break the law and they get convicted but they get off with a slap on the wrist. We need to legislate a dismantling of barriers to new entrants in the sectors they dominate. Competition for the consumer dollar is the only thing that can force them to be more honest. They need to see that their customers are leaving for something better, otherwise they'll never improve.
But our elected officials have crafted laws and an enforcement system which make 'something better' impossible (or at least highly uneconomical).
Parallel to this if open source projects can develop software which is easier for the user to change via a PR, they totally should. We can and should have the best of both worlds. We should have the big companies producing better "boxed" software. Plus we should have more flexibility to build, tweak and run whatever we want.
So everybody will be using (sometimes slightly, sometimes entirely) different software. Like mutations, these adapt to the specific problems in the situation they were prompted to be programmed.
The skill for feature thing is just horrible, it's wasteful to everyone but the maintainer. It feels like a YOLO people are getting away with because people drank some kool-aid.
I spent 3 months adopting Codex and Claude Code SDKs only to realize they're just vendor lock-in and brittle. They're intended to be used as CLI so it's not programmable enough as a library. After digging into OpenClaw codebase, I can safely say that the most of its success comes from the underlying harness, pi agent.
pi plugins support adding hooks at every stage, from tool calls to compaction and let you customize the TUI UI as well. I use it for my multi-tenant Openclaw alternative https://github.com/lobu-ai/lobu
If you're building an agent, please don't use proprietary SDKs from model providers. Just stick to ai-sdk or pi agent.
My current fave harness. I've been using it to great effect, since it is self-extensible, and added support for it to https://github.com/rcarmo/vibes because it is so much faster than ACP.
I think the thesis of Pi is that there isn't much special about agents.
Model + prompt + function calls.
There are many such wrappers, and they differ largely on UI deployment/integration. Harness feels like a decent term, though "coding harness" feels a bit vague.
The better web UI is now part of https://github.com/rcarmo/piclaw (which is essentially the same, but with more polish and a claw-like memory system). So you can pick if you want TS or Python as the back-end :)
The claw version’s web UI essentially has better thinking output, more visibility of tool calls, and slightly better SSE streaming. I’ve backported some of it to vibes, but if you want to borrow UI stuff, the better bits are in piclaw. I use both constantly on my phone/desktop.
I haven’t met a single person who has tried pi for a few days and not made it their daily driver. Once you taste the freedom of being able to set up your tool exactly how you like, there’s really no going back.
> I haven’t met a single person who has tried pi for a few days and not made it their daily driver.
Pleased to meet you!
For me, it just didn’t compare in quality with Claude CLI and OpenCode. It didn’t finish the job. Interesting for extending, certainly, but not where my productivity gains lie.
I am building an entire GPT model framework from the ground up in Typescript + small amounts of c bindings for gpu stuff. https://github.com/thomasdavis/alpha2 (using claude)
Don't hate me aha and no, there is no reason other than I can
It’s straightforward: JavaScript is a dynamic language, which allows code (for instance, code implementing an extension to the harness) to be executed and loaded while the harness is running.
This is quite nice — I do think there’s a version of pi’s design choices which could live in a static harness, but fully covering the same capabilities as pi without a dynamic language would be difficult. (You could imagine specifying a programmable UI, etc — various ways to extend the behavior of the system, and you’d like end up with an interpreter in the harness)
At least, you’d like to have a way to hot reload code (Elixir / Erlang could be interesting)
I'm super on board the rust train right now & super loving it. But no, code hot loading is not common.
Most code in the world is dead code. Most languages are for dead code. It's sad. Stop writing dead code (2022) was no where near the first, is decades and decades late in calling this out, but still a good one. https://jackrusher.com/strange-loop-2022/
Sure, but why implement a novel language with said feature if your concern is a harness ... not on implementing a brand new language with this feature?
I built my own harness on Elixir/Erlang[0]. It's very nice, but I see why TypeScript is a popular choice.
No serialization/JSON-RPC layer between a TS CLI and Elixir server. TS TUI libraries utilities are really nice (I rewrote the Elixir-based CLI prototype as it was slowing me down). Easy to extend with custom tools without having to write them in Elixir, which can be intimidating.
But you're right that Erlang's computing vision lends itself super well to this problem space.
Fwiw @dicklesworthstone / jeff Emanuel is definitely my favorite dragon rider right now, doing the most with AI, to the most effect.
Their agent mail was great & very early in agent orchestration. Code agent search is amazing & will tell you what's happening in every harness. Their Franktui is a ridiculously good rust tui. They have project after project after project after project and they are all so good.
yes! I just don't understand that as well. Up until some time ago claud code's preferred install was a npm i, wasn't it? Please serious answers for why anyone would use a web language for a terminal app
Yes. It seems to be the term that stands out the most, as terms like "AI coding assistant", "agentic coding framework", etc. are too vague to really differentiate these tools.
"harness" fits pretty nicely IMO. It can be used as a single word, and it's not too semantically overloaded to be useful in this context.
A harness is a collection of stubs and drivers configured to assist with automation or testing. It's a standard term often used in QA as they've been automating things for ages before Gen Ai came on to the scene.
I've been using pi via the pi-coding-agent Emacs package, which uses its RPC mode to populate a pair of Markdown buffers (one for input, one for chat), which I find much nicer than the awful TUIs used by harnesses like gemini-cli (Emacs works perfectly well as a TUI too!).
The extensibility is really nice. It was easy to get it using my preferred issue tracker; and I've recently overridden the built-in `read` and `write` commands to use Emacs buffers instead. I'd like to override `edit` next, but haven't figured out an approach that would play to the strengths of LLMs (i.e. not matching exact text) and Emacs (maybe using tree-sitter queries for matches?). I also gave it a general-purpose `emacs_eval`, which it has used to browse documentation with EWW.
Nice! I'm curious to hear how you're mapping `read` and `write` to Emacs buffers. Does that mean those commands open those files in Emacs and read and write them there?
Let me also drop a link to the Pi Emacs mode here for anyone who wants to check it out: https://github.com/dnouri/pi-coding-agent -- or use: M-x package-install pi-coding-agent
We've been building some fun integrations in there like having RET on the output of `read`, `write`, `edit` tool calls open the corresponding file and location at point in an Emacs buffer. Parity with Pi's fantastic session and tree browsing is hopefully landing soon, too. Also: Magit :-)
Pi was probably the best ad for Claude Code I ever saw.
After my max sub expired I decided to try Kimi on a more open harness, and it ended up being one of the worst (and eye opening experiences) I had with the agentic world so far.
It was completely alienating and so much 'not for me', that afterwards I went back and immediately renewed my claude sub.
I had a very similar experience. I have different preferences, but ultimately, my takeaway was that if I want to follow my own version of their philosophy, I should just create my own thing.
In the meantime, the codex/cc defaults are better for me.
> I would say that the project actively expects you to be downloading them to fill any missing gaps you might have.
Where did you get this perspective from?
> I thought pi and its tools were supposed to be minimal and extensible. So why is a subagent extension bundling six agents I never asked for that I can’t disable or remove?
Why do you think a random subagents extension is under the same philosophy as pi?
Your blog post says little about pi proper, it's essentially concerned with issues you had with the ecosystem of extensions, often made by random people who either do or do not get the philosophy? Why would that be up to pi to enforce?
> if I start the agent in ./folder then anything outside of ./folder should be off limits unless I explicitly allow it, and the same goes for bash where everything not on an allowlist should be blocked by default.
Here's the problem with Claude Code: it acts like it's got security, but it's the equivalent of a "do not walk on grass" sign. There's no technical restrictions at play, and the agent can (maliciously or accidentally) bypass the "restrictions".
That's why Pi doesn't have restrictions by default. The logic is: no matter what agent you are using, you should be using it in a real sandbox (container, VM, whatever).
But the agent has to interact with the world; fetch docs, push code, fetch comments, etc. You can't sandbox everything. So you push that configuration to your sandbox, which is a worse UX that the harness just asking you at the right time what you'd like to do.
I've been using Pi day to day recently for simple, smaller tasks. It's a great harness for use with smaller parameter size models given the system prompt is quite a bit shorter vs Claude or Codex (and it uses a nice small set of tools by default).
For local models I've been trying it with GLM-4.7-Flash and the new LFM2 24B model. I'm excited to try it with the new Qwen3.5 models that came out today as well.
Pi ships with powerful defaults but skips features like sub-agents and plan mode
Does anyone have an idea as to why this would be a feature? don't you want to have a discussion with your agent to iron out the details before moving onto the implementation (build) phase?
In any case, looks cool :)
EDIT 1: Formatting
EDIT 2: Thanks everyone for your input. I was not aware of the extensibility model that pi had in mind or that you can also iterate your plan on a PLAN.md file. Very interesting approach. I'll have a look and give it a go.
Agreed. I rarely find the guardrails of plan to be necessary; I basically never use it on opencode. I have some custom commands I use to ask for plan making, discussion.
As for subagents, Pi has sessions. And it has a full session tree & forking. This is one of my favorite things, in all harnesses: build the thing with half the context, then keep using that as a checkpoint, doing new work, from that same branch point. It means still having a very usable lengthy context window but having good fundamental project knowledge loaded.
Has anyone used an open coding agent in headless mode? I have a system cobbled together with exceptions going to a centralized system where I can then have each one pulled out and `claude -p`'d but I'd rather just integrate an open coding agent into the loop because it's less janky and then I'll have it try to fix the problem and propose a PR for me to review. If anyone else has used pi.dev or opencode or aider in this mode (completely non-interactive until the PR) I'd be curious to hear.
EDIT: Thank you to both responders. I'll just try the two options out then.
pi has an RPC mode which just sends/receives JSON lines over stdio (including progress updates, and "UI" things like asking for confirmation, if it's configured for that).
That's how the pi-coding-agent Emacs package interacts with pi; and it's how I write automated tests for my own pi extensions (along with a dummy LLM that emits canned responses).
Run Qwen3-coder-next locally. That's what I'm doing (using LMstudio). It's actually a surprisingly capable model. I've had it working on some LLVM-IR manipulation and microcode generation for a kind of VLIW custom processor. I've been pleasantly surprised that it can handle this (LLVM is not easy) - there are also verilog code that define the processor's behavior that it reads to determine the microcode format and expected processor behavior. When I do hit something that it seems to struggle with I can go over to antigravity and get some free Gemini 3 flash usage.
Qwen3 Coder Next in llama.cpp on my own machine. I'm an AI hater, but I need to experiment with it occasionally, I'm not going to pay someone rent for something they trained on my own GitHub, Stack overflow, and Reddit posts.
MiniMax has an incredibly affordable coding plan for $10/month. It has a rolling five hour limit of 100 prompts. 100 prompts doesn't sound like much, but in typical AI company accounting fashion, 1 prompt is not really 1 prompt. I have yet to come even close to hitting the limit with heavy use.
I’m working with a friend to build an ui around Pi to make it more user friendly for people who prefer to work with a gui (ala conductor). You can check out the repo: https://github.com/philipp-spiess/modern
Interesting approach to planning via extensions. I took a similar direction with enforcement. A governance loop that hooks into the agent's tool calls and blocks
execution until protocol is followed. Every 10 actions (configurable), the agent re-centers. No permission popups, but the agent literally can't skip steps.
The way you’re able to extend the harness through extension/hook architecture is really cool.
Eg some form of comprehensive planning/spec workflow is best modeled as an extension vs natively built in. And the extension still ends up feeling “native” in use
Yeah I wrote a small landlock wrapper using go-landlock to sandbox pi that works well (not public, similar projects are landrun and nono).
Note that if you sandbox to literally just the working directly, pi itself wont run since pretty much every linux application needs to be able to read from /usr and /etc
I do this with an extension. I run all bash tools with bwrap and ACLs for the write and edit tools. Serves my purposes. Opens up access to other required directories, at least for git and rust.
I think I published it. Check the pi package page.
Pi makes GPT-5.3-Codex act about on par with Claude easily.
There's something in the default Codex harness that makes it fight with both arms behind its back, maybe the sandboxing is overly paranoid or something.
With Pi I can one-shot many features faster and more accurately than with Codex-cli.
Pi treats you like an adult and shows whatever the fuck LLM is doing rather than actively hiding shit from the user. And just for that, once you tasted the freedom and transparency, there’s no way to go back to CC.
> Why is it insecure, well, Pi tells you >No permission popups.
Pi supports permission popups, but doesn't use them by default. Their example extensions show how to do it (add an event listener for `tool_call` events; to block the call put `block: true` in its result).
> there's no secure way to know whether what they're asking to is what they'll actually do
What do you mean? `tool_call` event listeners are given the parameters of the tool call; so e.g. a call to the `bash` tool will show the exact command that will execute (unless we block it, of course).
To me, the most interesting thing about Pi and the "claw" phenomenon is what it means for open source. It's becoming passé to ask for feature requests and even to submit PRs to open source repos. Instead of extensions you install, you download a skill file that tells a coding agent how to add a feature. The software stops being an artifact and starts being a living tool that isn't the same as anyone else's copy. I'm curious to see what tooling will emerge for collaborating with this new paradigm.
I see this happening, too.
We know that a lack of control over their environment makes animals, including humans, depressed.
The software we use has so much of this lack of control. It's their way, their branding, their ads, their app. You're the guest on your own device.
It's no wonder everyone hates technology.
A world with software that is malleable, personal, and cheap - this could do a lot of good. Real ownership.
The nerds could always make a home with their linux desktop. Now everyone can. It'll change the equation.
I'm quite optimistic for this future.
That's just because corporations got greedy and made their apps suck.
Strip away the ads, the data harvesting, add back the power features, and we'll be happy again. I'm more willing than ever to pay a one-time fee good software. I've started donating to all the free apps I use on a regular basis.
I don't want to own my own slop. That doesn't help me. Use your AI tools to build out the software if you want, but make sure it does a good job. Don't make me fiddle with indeterministic flavor-of-the-month AI gents.
I think there's room for both visions. Big Tech is generating more toxic sludge than ever, and yeah sure this is because they're greedy, but more precisely the root cause is how they lobbied Washington and our elected officials agreed to all kinds of pro-corporate, anti-human legislation. Like destroying our right to repair, like criminalizing "circumvention" measures in devices we own, like insane life-destroying penalties for copyright infringement, like looking the other way when Big Tech broke anti-trust laws, etc.
The Big Tech slop can only be fixed in one way, and actually it's really predictable and will work - we need to fix the laws so that they put the rights and flourishing of human beings first, not the rights and flourishing of Big Tech. We need to fix enforcement because there are so many times that these companies just break the law and they get convicted but they get off with a slap on the wrist. We need to legislate a dismantling of barriers to new entrants in the sectors they dominate. Competition for the consumer dollar is the only thing that can force them to be more honest. They need to see that their customers are leaving for something better, otherwise they'll never improve.
But our elected officials have crafted laws and an enforcement system which make 'something better' impossible (or at least highly uneconomical).
Parallel to this if open source projects can develop software which is easier for the user to change via a PR, they totally should. We can and should have the best of both worlds. We should have the big companies producing better "boxed" software. Plus we should have more flexibility to build, tweak and run whatever we want.
And how great it will be to troubleshoot any issues because everyone is basically running a distinct piece of software
I don’t want to be the one who has to upgrade this software + vibe coded patches.
It’s going to be very likely that once something is patched is to be considered as diverged and very hard to upgrade
... made minutes ago.
So everybody will be using (sometimes slightly, sometimes entirely) different software. Like mutations, these adapt to the specific problems in the situation they were prompted to be programmed.
The skill for feature thing is just horrible, it's wasteful to everyone but the maintainer. It feels like a YOLO people are getting away with because people drank some kool-aid.
I spent 3 months adopting Codex and Claude Code SDKs only to realize they're just vendor lock-in and brittle. They're intended to be used as CLI so it's not programmable enough as a library. After digging into OpenClaw codebase, I can safely say that the most of its success comes from the underlying harness, pi agent.
pi plugins support adding hooks at every stage, from tool calls to compaction and let you customize the TUI UI as well. I use it for my multi-tenant Openclaw alternative https://github.com/lobu-ai/lobu
If you're building an agent, please don't use proprietary SDKs from model providers. Just stick to ai-sdk or pi agent.
My current fave harness. I've been using it to great effect, since it is self-extensible, and added support for it to https://github.com/rcarmo/vibes because it is so much faster than ACP.
Which ones have you compared it against?
Wdym harness? Its a coding agent
I think the thesis of Pi is that there isn't much special about agents.
Model + prompt + function calls.
There are many such wrappers, and they differ largely on UI deployment/integration. Harness feels like a decent term, though "coding harness" feels a bit vague.
wow, i love this! was about to build this myself, but this looks exactly what i want.
The better web UI is now part of https://github.com/rcarmo/piclaw (which is essentially the same, but with more polish and a claw-like memory system). So you can pick if you want TS or Python as the back-end :)
if i ever want a claw, i'd obv. go with this :)
The claw version’s web UI essentially has better thinking output, more visibility of tool calls, and slightly better SSE streaming. I’ve backported some of it to vibes, but if you want to borrow UI stuff, the better bits are in piclaw. I use both constantly on my phone/desktop.
I haven’t met a single person who has tried pi for a few days and not made it their daily driver. Once you taste the freedom of being able to set up your tool exactly how you like, there’s really no going back.
and you can build cool stuff on top of it too!
> I haven’t met a single person who has tried pi for a few days and not made it their daily driver.
Pleased to meet you!
For me, it just didn’t compare in quality with Claude CLI and OpenCode. It didn’t finish the job. Interesting for extending, certainly, but not where my productivity gains lie.
People seem to be really enjoying rolling everything themselves these days...
What self-built capabilities do you like the most that claude code doesn't offer?
Preconfigured PI: https://github.com/can1357/oh-my-pi
Big fan of this fork, been using it for everything for the last couple of weeks.
Went from codex/claude code -> opencode -> pi -> oh-my-pi
I'd quite like the web tools from oh-my-pi, but able to be extracted to a normal pi tool or plugin... Maybe I should look into that sometime...
Why not OpenCode?
Hugging Face now provides instructions for using local models in Pi:
https://x.com/victormustar/status/2026380984866710002
Pi has made all the right design choices. Shout out to Mario (and Armin the OG stan) — great taste shows itself.
I do not understand why in the age of ai coding we would implement this in javascript
I am building an entire GPT model framework from the ground up in Typescript + small amounts of c bindings for gpu stuff. https://github.com/thomasdavis/alpha2 (using claude)
Don't hate me aha and no, there is no reason other than I can
It’s straightforward: JavaScript is a dynamic language, which allows code (for instance, code implementing an extension to the harness) to be executed and loaded while the harness is running.
This is quite nice — I do think there’s a version of pi’s design choices which could live in a static harness, but fully covering the same capabilities as pi without a dynamic language would be difficult. (You could imagine specifying a programmable UI, etc — various ways to extend the behavior of the system, and you’d like end up with an interpreter in the harness)
At least, you’d like to have a way to hot reload code (Elixir / Erlang could be interesting)
This is my intuition, at least.
Code hotloading isn't a particularly difficult feature to implement in any language.
Rust can't even dynamically link!
I'm super on board the rust train right now & super loving it. But no, code hot loading is not common.
Most code in the world is dead code. Most languages are for dead code. It's sad. Stop writing dead code (2022) was no where near the first, is decades and decades late in calling this out, but still a good one. https://jackrusher.com/strange-loop-2022/
Incredible talk and I agree with all the things and I've worked on this problem a bunch.
But Rust can dynamically link with dylib but I believe it's still unstable.
It can also dynamically load with libloading.
Sure, but why implement a novel language with said feature if your concern is a harness ... not on implementing a brand new language with this feature?
I built my own harness on Elixir/Erlang[0]. It's very nice, but I see why TypeScript is a popular choice.
No serialization/JSON-RPC layer between a TS CLI and Elixir server. TS TUI libraries utilities are really nice (I rewrote the Elixir-based CLI prototype as it was slowing me down). Easy to extend with custom tools without having to write them in Elixir, which can be intimidating.
But you're right that Erlang's computing vision lends itself super well to this problem space.
[1]: https://github.com/matteing/opal
There is a Rust port: https://github.com/Dicklesworthstone/pi_agent_rust
Fwiw @dicklesworthstone / jeff Emanuel is definitely my favorite dragon rider right now, doing the most with AI, to the most effect.
Their agent mail was great & very early in agent orchestration. Code agent search is amazing & will tell you what's happening in every harness. Their Franktui is a ridiculously good rust tui. They have project after project after project after project and they are all so good.
Didn't know they had a rust Pi. Nice.
yes! I just don't understand that as well. Up until some time ago claud code's preferred install was a npm i, wasn't it? Please serious answers for why anyone would use a web language for a terminal app
Because it's what the person writing it's preferred language.
So it can share code with the web app.
Because writing it in javascript is easier than writing it in raw brute forced assembly.
i wrote an agent in zig, it kinda sucks tho. the language is just words
See also: pz: pi coding-agent in Zig
https://news.ycombinator.com/item?id=47120784
Is that an official term "coding harness"
Wondering if you wanted a similar interface (though a GUI not just CLI) where it's not for coding what would you call that?
Same idea cycle through models, ask question, drag-drop images, etc...
Yes. It seems to be the term that stands out the most, as terms like "AI coding assistant", "agentic coding framework", etc. are too vague to really differentiate these tools.
"harness" fits pretty nicely IMO. It can be used as a single word, and it's not too semantically overloaded to be useful in this context.
LLM harness has been in vogue for a year now…
A harness is a collection of stubs and drivers configured to assist with automation or testing. It's a standard term often used in QA as they've been automating things for ages before Gen Ai came on to the scene.
Yes, it is also a device used to control the movement of work animals, which farmers have been using for ages before QA came on to the scene.
I've been using pi via the pi-coding-agent Emacs package, which uses its RPC mode to populate a pair of Markdown buffers (one for input, one for chat), which I find much nicer than the awful TUIs used by harnesses like gemini-cli (Emacs works perfectly well as a TUI too!).
The extensibility is really nice. It was easy to get it using my preferred issue tracker; and I've recently overridden the built-in `read` and `write` commands to use Emacs buffers instead. I'd like to override `edit` next, but haven't figured out an approach that would play to the strengths of LLMs (i.e. not matching exact text) and Emacs (maybe using tree-sitter queries for matches?). I also gave it a general-purpose `emacs_eval`, which it has used to browse documentation with EWW.
Nice! I'm curious to hear how you're mapping `read` and `write` to Emacs buffers. Does that mean those commands open those files in Emacs and read and write them there?
Let me also drop a link to the Pi Emacs mode here for anyone who wants to check it out: https://github.com/dnouri/pi-coding-agent -- or use: M-x package-install pi-coding-agent
We've been building some fun integrations in there like having RET on the output of `read`, `write`, `edit` tool calls open the corresponding file and location at point in an Emacs buffer. Parity with Pi's fantastic session and tree browsing is hopefully landing soon, too. Also: Magit :-)
Note there is a fork oh-my-pi: https://github.com/can1357/oh-my-pi of https://blog.can.ac/2026/02/12/the-harness-problem/ fame. I use it as a daily driver but I also love pi.
Pi was probably the best ad for Claude Code I ever saw.
After my max sub expired I decided to try Kimi on a more open harness, and it ended up being one of the worst (and eye opening experiences) I had with the agentic world so far.
It was completely alienating and so much 'not for me', that afterwards I went back and immediately renewed my claude sub.
https://www.thevinter.com/blog/bad-vibes-from-pi
I had a very similar experience. I have different preferences, but ultimately, my takeaway was that if I want to follow my own version of their philosophy, I should just create my own thing.
In the meantime, the codex/cc defaults are better for me.
> I would say that the project actively expects you to be downloading them to fill any missing gaps you might have.
Where did you get this perspective from?
> I thought pi and its tools were supposed to be minimal and extensible. So why is a subagent extension bundling six agents I never asked for that I can’t disable or remove?
Why do you think a random subagents extension is under the same philosophy as pi?
Your blog post says little about pi proper, it's essentially concerned with issues you had with the ecosystem of extensions, often made by random people who either do or do not get the philosophy? Why would that be up to pi to enforce?
> if I start the agent in ./folder then anything outside of ./folder should be off limits unless I explicitly allow it, and the same goes for bash where everything not on an allowlist should be blocked by default.
Here's the problem with Claude Code: it acts like it's got security, but it's the equivalent of a "do not walk on grass" sign. There's no technical restrictions at play, and the agent can (maliciously or accidentally) bypass the "restrictions".
That's why Pi doesn't have restrictions by default. The logic is: no matter what agent you are using, you should be using it in a real sandbox (container, VM, whatever).
But the agent has to interact with the world; fetch docs, push code, fetch comments, etc. You can't sandbox everything. So you push that configuration to your sandbox, which is a worse UX that the harness just asking you at the right time what you'd like to do.
hypegrift
I've been using Pi day to day recently for simple, smaller tasks. It's a great harness for use with smaller parameter size models given the system prompt is quite a bit shorter vs Claude or Codex (and it uses a nice small set of tools by default).
Which models do you use and what for? I'm looking for ideas to play with.
For local models I've been trying it with GLM-4.7-Flash and the new LFM2 24B model. I'm excited to try it with the new Qwen3.5 models that came out today as well.
Coming from OpenClaw, it's pretty amazing how fast pi is, particularly paired with Qwen3 that dropped today. It's a magical time.
What dropped today? Wasn't Qwen3 Coder Next released beginning of the month?
Qwen3.5 released a couple of days ago but I'm not that RAM rich
Alibaba released a whole set of new Qwen 3.5 models including a ~120B and a ~35B MoE.
Indeed, it seems to just works with a self hosted Qwen3 coder next.
Pi ships with powerful defaults but skips features like sub-agents and plan mode
Does anyone have an idea as to why this would be a feature? don't you want to have a discussion with your agent to iron out the details before moving onto the implementation (build) phase?
In any case, looks cool :)
EDIT 1: Formatting EDIT 2: Thanks everyone for your input. I was not aware of the extensibility model that pi had in mind or that you can also iterate your plan on a PLAN.md file. Very interesting approach. I'll have a look and give it a go.
See my comment in the thread but there is an intuitive extension architecture that makes integrating these type of things feel native.
https://github.com/badlogic/pi-mono/tree/main/packages/codin...
I plan all the time. I just tell Pi to create a Plan.md file, and we iterate on it until we are ready to implement.
Agreed. I rarely find the guardrails of plan to be necessary; I basically never use it on opencode. I have some custom commands I use to ask for plan making, discussion.
As for subagents, Pi has sessions. And it has a full session tree & forking. This is one of my favorite things, in all harnesses: build the thing with half the context, then keep using that as a checkpoint, doing new work, from that same branch point. It means still having a very usable lengthy context window but having good fundamental project knowledge loaded.
Check https://pi.dev/packages
There are already multiple implementations of everything.
With a powerful and extensible core, you don't need everything prepackaged.
Has anyone used an open coding agent in headless mode? I have a system cobbled together with exceptions going to a centralized system where I can then have each one pulled out and `claude -p`'d but I'd rather just integrate an open coding agent into the loop because it's less janky and then I'll have it try to fix the problem and propose a PR for me to review. If anyone else has used pi.dev or opencode or aider in this mode (completely non-interactive until the PR) I'd be curious to hear.
EDIT: Thank you to both responders. I'll just try the two options out then.
pi has an RPC mode which just sends/receives JSON lines over stdio (including progress updates, and "UI" things like asking for confirmation, if it's configured for that).
That's how the pi-coding-agent Emacs package interacts with pi; and it's how I write automated tests for my own pi extensions (along with a dummy LLM that emits canned responses).
Been using pi exactly for this and it's working great!
You probably want to look into pi then - it's extremely extensible.
you can run https://block.github.io/goose/ in headless mode (I work on goose)
fast-agent lets you do this as well (and has a skill in its default skills repo to help with automation/running in container/hf job).
there is also pz a drop-in replacement for pi rewritten in Zig. 1.7MB static binary, 3ms startup, 1.4MB RAM idle. Find more at:
https://github.com/elyase/awesome-personal-ai-assistants?tab...
Cool, thanks for this. What about the extensions though? For me the point about pi is minimal base plus configurable extensions you choose.
Direct link to pz for those on mobile: https://github.com/joelreymont/pz
Anyone tried pi with 5.3-codex vs codex cli?
What are people using to cost efficiently use this? I was using a Google Ultra sub which gave enough but that’s gone now.
ChatGPT $20/month is alright but I got locked out for a day after a couple hours. Considering the GitHub pro plus plan.
Run Qwen3-coder-next locally. That's what I'm doing (using LMstudio). It's actually a surprisingly capable model. I've had it working on some LLVM-IR manipulation and microcode generation for a kind of VLIW custom processor. I've been pleasantly surprised that it can handle this (LLVM is not easy) - there are also verilog code that define the processor's behavior that it reads to determine the microcode format and expected processor behavior. When I do hit something that it seems to struggle with I can go over to antigravity and get some free Gemini 3 flash usage.
What kind of hardware do you run it on?
Same here
Qwen3 Coder Next in llama.cpp on my own machine. I'm an AI hater, but I need to experiment with it occasionally, I'm not going to pay someone rent for something they trained on my own GitHub, Stack overflow, and Reddit posts.
FWIW the lockout probably wasn't related... maybe the content you were working on or your context window management somehow triggered something?
You could try minimax 2.5 via openrouter.
MiniMax has an incredibly affordable coding plan for $10/month. It has a rolling five hour limit of 100 prompts. 100 prompts doesn't sound like much, but in typical AI company accounting fashion, 1 prompt is not really 1 prompt. I have yet to come even close to hitting the limit with heavy use.
I’m working with a friend to build an ui around Pi to make it more user friendly for people who prefer to work with a gui (ala conductor). You can check out the repo: https://github.com/philipp-spiess/modern
In the same spirit, I also ported a planning UI extension for Pi.
https://plannotator.ai/blog/plannotator-meets-pi/
ive been using pi for about a week as daily driver and so far im happy with it. I really like the modular concept and also that its rather minimal
Interesting approach to planning via extensions. I took a similar direction with enforcement. A governance loop that hooks into the agent's tool calls and blocks execution until protocol is followed. Every 10 actions (configurable), the agent re-centers. No permission popups, but the agent literally can't skip steps.
Open source: https://github.com/isagawa-co/isagawa-kernel
The way you’re able to extend the harness through extension/hook architecture is really cool.
Eg some form of comprehensive planning/spec workflow is best modeled as an extension vs natively built in. And the extension still ends up feeling “native” in use
too bad I cannot star this.. https://github.com/badlogic/pi-mono/tree/main/packages/codin...
I’ve been testing it for a few days on pretty much clean install (no customizations/extensions) and it’s ok. Not sure if I like it yet.
What's a coding harness? Claude Code is a "harness" and not a TUI?
The fact that it's a tui isn't particularly relevant. It could be a gui or cli and provide very similar value.
Nearly all of its value is facilitating your interaction with the LLM, the tools it can use, and how it uses them.
If you run Claude Code with `-p --output-format json` it's no longer a TUI, but it's still a harness.
Excited to give this a try, looks really well done.
Anyone managed to run pi in a completely sandboxed environment? It can only access the cwd and subdirectories
I run mine inside https://github.com/rcarmo/agentbox (with https://github.com/rcarmo/webterm)
Yeah I wrote a small landlock wrapper using go-landlock to sandbox pi that works well (not public, similar projects are landrun and nono).
Note that if you sandbox to literally just the working directly, pi itself wont run since pretty much every linux application needs to be able to read from /usr and /etc
I’ve been tinkering with Gondolin, a micro-vm agent sandbox.
Here’s an example config: https://github.com/earendil-works/gondolin/blob/main/host/ex...
I do this with an extension. I run all bash tools with bwrap and ACLs for the write and edit tools. Serves my purposes. Opens up access to other required directories, at least for git and rust.
I think I published it. Check the pi package page.
But I can't use my Codex plan with it, right? I have to use an API key?
You can use your Codex plan with it. OpenAI endorsed it several weeks ago, as far as I remember. That could change, however, but now seems safe.
You can use your Claude or Gemini plan with it too for now, though Anthropic and Google have made it clear this is a ToS violation.
Pi makes GPT-5.3-Codex act about on par with Claude easily.
There's something in the default Codex harness that makes it fight with both arms behind its back, maybe the sandboxing is overly paranoid or something.
With Pi I can one-shot many features faster and more accurately than with Codex-cli.
Naming skills though...
Another batteries included pi setup. Built a lightweight mobile webui to run it on termux and code on my phone.
https://github.com/mikeyobrien/rho
Pi treats you like an adult and shows whatever the fuck LLM is doing rather than actively hiding shit from the user. And just for that, once you tasted the freedom and transparency, there’s no way to go back to CC.
I think OpenCode is the same.
They are all open source though so you can just find out whats going on if you want right?
I mean using the captive agents is much cheaper than supplying your api key to a 3rd party agent.
Wtf is that example gif?
The prompt shown is
"Who's your daddy and what does he do?"
Is this a joke or tech? Is the author a dev or a clown?
No one cares about your opinions.
This coding agent certainly couldn't give a fuck.
It’s a quote from the movie Kindergarten Cop.
The backing to OpenClaw/MoltBot whatever they're calling themselves. Why is it insecure, well, Pi tells you >No permission popups.
Anyway, even if you give your agent permission, there's no secure way to know whether what they're asking to is what they'll actually do, etc.
> Why is it insecure, well, Pi tells you >No permission popups.
Pi supports permission popups, but doesn't use them by default. Their example extensions show how to do it (add an event listener for `tool_call` events; to block the call put `block: true` in its result).
> there's no secure way to know whether what they're asking to is what they'll actually do
What do you mean? `tool_call` event listeners are given the parameters of the tool call; so e.g. a call to the `bash` tool will show the exact command that will execute (unless we block it, of course).
you want to put agents in a sandbox instead such as bwrap anyways.
Just how expensive was that domain?
README on Github says “pi.dev domain graciously donated by exe.dev” (though that doesn’t say anything about the original price of course).
oh that's kind. i hope they keep the old domain up too though: https://shittycodingagent.ai/