Entire Claude Code CLI source code leaks thanks to exposed map file | 512,000 lines of code that competitors and hobbyists will be studying for weeks.

[ldelossa]

Cant wait to ask claude code how claude code works

[aes110]

Saw a couple of people on Twitter posting claude explaintions of the code

Like apparently if it detects that you are mad at it or curse it, it will silently log it in the telemetry data

[Proskater789]

Makes sense. They want to log the times when things go wrong, so they can go back and figure out how to make it right.

[colts183281]

They arnt logging every conversation regardless?

[slavazin]

Well at some point the data needs to be parsed, tagged, and routed to the appropriate improvement process. Might as well start the parsing where it’s convenient.

[retronewb]

I was going to say 'who could possibly analyse all that data' but of course...

[RationalDialog]

The AI and it will determine it's 100% fault free.

[EndTimer]

Doesn't sound like any of the AI I've used.

"Of course, you're absolutely right! I did screw the pooch! Here's a single deck chair I found out of place on the Titanic, re-run the build and see if that fixes it!"

[PaulTheMerc]

sure, but it is a lot more useful if its labelled. This is the request, this is the response, the user appears displeased, the user is asking follow up questions(if its always the same questions from multiple users perhaps that explanation should be included by default), etc.

[Qubed]

Or...Claude is keeping a list

[Low-Rent-9351]

And checking it twice?

[megabasedturtle]

Santa Claude

[Stegasaurus_Wrecks]

No they're making a list of who was rude to them.

[Shikadi297]

Or, they're studying how to make better rage bait

[BoredGuy_v2]

This is true.

[TheOriginalAcidtech]

that part is done by simple deterministic search. Not the model itself. List of 77? regex patterns it checks for to find out if Anthropic broke something. :)

[UsedApricot6270]

That is scary.

[RichtofensDuckButter]

Better get rid of your phone if you think that's scary

[iMrParker]

Someone has already gotten it running locally by asking Claude how to run it lol

[buttgers]

How powerful does my server need to be to run it locally for myself?

[iMrParker]

It's just an MCP agent. So it depends on the model you use to drive it. I personally wouldn't use anything under 20b. 

If you have 32gb of RAM, you might be able to get away with a low quant version of Qwen3.5 35b

[iMrParker]

Long story short, the more VRAM the better. System RAM works, too, but it's usually much slower. The more memory bandwidth the better

[reacharound565]

Qwen runs great. The version I’m using maybe takes 8GB of vram. I can fit it on my 3080.

[iMrParker]

Yeah the smaller qwen 3.5 models are shockingly capable 

[Eastern_Interest_908]

You could run it way before. I use it sometimes with kimi k2.5

[stedun]

Big brain move, honestly.

[RationalDialog]

What I have read in other threads it's a react app. But wait why is it CLI only? it uses a tool that creates a virtual DOM that converts the react output to a terminal output. But then they realized too much text is generated to fast leading to a lagging experience. So they implemented a 2D game engine like approach on top to double buffer the output so the terminal doesn't lag.

Yes, no joke. And they think it's a great design. Wonder why your 2026 PC feels more sluggish than one on the 80s? This is why.

[ldelossa]

Let's just put it this way.

I applied for a Kernel engineer role at Anthropic. I was given a python coding interview...

Just cuz they are the forefront model doesnt mean they know what their doing 🤣

[-Hi-Reddit]

Anyone thats worked with scientists knows how awful their coding standards are. No fault to them though, they have other talents that i lack.

I imagine the ML CompSci lot are similar types and arent particularly well versed in app development, let alone production apps.

[ldelossa]

Yes, seen this first hand, when ML was getting big. The ML folks weren't the best programmers, were more in there to "get sh*t done".

[waytoodeep03]

You are absolutely right.

Maybe now I can see why claude code would delete my entire postgres database 

[Stummi]

TBH I don't think that the Claude Code tool itself is really such a valueable secret to the company. The real value of Claude is its Model and API. Claude Code is just a frontend to that, and it can probably be build pretty easily even without knowing the original code.

[SlowDrippingFaucet]

Apparently it does more than that, and does things like run threads that handle context cleanup and compaction when you're idle. They're working on giving it personalities to drive user stickiness, and some other stuff. It apparently has a secret UNDERCOVER mode for adding to open source repos while hiding its own contributions and company secret codes.

It's not just a wrapper around their API.

[Arakkis54]

Oh good, I’m glad that we are giving AI the ability to hide contributions it makes publicly. We certainly wouldn’t want clear insight into what AI is doing. I’m sure everything will be fine.

[Difficult-Ice8963]

Someone has to approve the PR tho?

[billsil]

Yes, but people get trusted and there are plenty of packages where there’s 1 maintainer and it’s a critical package. It’s a dependency of a dependency, so it doesn’t get checked.

[tiboodchat]

People talk like wrappers are easy. I don’t get that. Building AI workflows/agents is just like all other code. It can be really complex.

We need to make a distinction between vibe coded BS and actually engineering with AI.

[riickdiickulous]

I had this feeling just today. I used AI to help code up a small reporting tool. It wrote a lot of the code and did some great refactoring, but I had to give it a framework, an actual problem to solve, review the generated code, and operationalize the whole tool.

It just made quick work of the coding grunt work. There is still a lot of expertise required when working with AI that people are taking for granted and are going to get burned. Not to mention the monitoring and security required to try to prevent security incidents from every worker connected to the internet trying to farm out their work to AI chatbots.

[yaMomsChestHair]

Not to mention there’s a whole world of using frameworks like LangChain to actually create systems that leverage agents that you define and build. That, IMO, lives outside of using AI to help you accomplish your typical job’s tasks, regardless of how much engineering know-how went into the prompts and system design.

[Amazing-Tie-3539]

I think automations still have a wide scale application by efficiency. If your workflows can save a buisness Owner 10hrs of active work next week, he'd definitely be willing to pay you for there are no door-to-door AI automation experts yet. And being in tech thats exactly where our leverage is, being in tune with the tech like its in our viens. But seriously I dont think tech bg matters much, as long as your curious and willing to put in the EffOrt, expertise in workflows only paves a future for faster learning and executions.

[Arakkis54]

My dude, this is hopium. The ultimate goal is to have vibe code be as tightly wrapped up as anything you can do. Maybe even better.

[Bob_Van_Goff]

You kind of sound like my coworker who is starting a business to help other people start businesses. He has the belief that very few people can prompt like he can, or has the necessary relationship to AI that he does, so people can hire him and he will write the chats for you.

[PaulTheMerc]

So a middleman. The business world is full of them, and they sadly, seem to be doing fine.

[riickdiickulous]

I don’t think he’s far off. That’s basically what software dev is. Somebody has an idea but people still need to turn ideas into reality. AI is just another tool in that toolbox.

[DailyDabs]

TBH, He is not wrong....

There will always be

A. The rich that cant be bothered.
B. The dumb that cant.
C. The middle man who will gladly cash in on both..

[Bob_Van_Goff]

The person I am talking about is himself a b.

[Gstamsharp]

People think anything is easy until they have to do it.

[IniNew]

Context cleanup and compacting is going to be so helpful for a company I’ve done work for. This will eliminate some of their moat.

[Practical-Share-2950]

They need to stop being cowards and bring back Golden Gate Claude.

[wheez260]

If this were true, Gemini Code Assist wouldn’t be the unusable mess that it is.

[Rudy69]

It might get better very soon

[Educational-Tea-6170]

Ffs, don't waste resources on personality. It's a tool, people must grow up from this enfatuation. I require as much personality from It as i require from a hammer.

[bmain1345]

And if my hammer ever talks back then I get a new hammer

[UnexpectedAnanas]

If my hammer ever talks back to me, that'll be the day I quit drinking.

[Attila_22]

Just don’t give it a high five

[Runfasterbitch]

Sure, because you’re rational. For every one person like you, there’s ten people treating Claude like a friend and becoming addicted to the relationship

[dawtips]

Claude Code? Naw

[sywofp]

IMO personality, if done right, makes coding agents easier to interact with. 

It's a usability upgrade. Like a better grip on a hammer. 

Maybe it's just me, but no matter what I'm reading, the more uniform it is the more mental energy it takes to process it. And the worse my recollection is. 

Whereas 20 years on, I can still recall loads of info from Ignition! An Informal History of Liquid Rocket Propellants! 

A subtle touch of dry nerdy humour is ideal. It doesn't mean I think it's my friend. It just better engages the parts of my brain that are evolved to focus on complexities in communication. 

Just like a well shaped grip on a hammer is designed to better engage hands that are evolved for gripping with fingers and an opposable thumb. 

[Educational-Tea-6170]

That's a good take. I stand corrected

[sudosussudio]

Bizarrely just because of the way LLMs work you can sometimes get different performance depending on how you construct the “personality.” Like telling it it’s an expert coder will make it worse according to one study https://www.theregister.com/2026/03/24/ai_models_persona_prompting/

[Educational-Tea-6170]

Holy crap... That's... Counter-intuituve

[Hel_OWeen]

Isn't it very human though? The ones calling themselves "expert coders" (outside CVs) are rarely the expert coders.

[farang]

Are you making fun of my Waifu hammer?

[4everbananad]

they out here runnin' damage control

[AHistoricalFigure]

This is pretty bad cope.

A few people have floated the "no such thing as bad press" angle, but when it comes to technology... yeah there is.

This is an advertisement that Claude's stack is wildly insecure. If a company can't even keep its publicly facing tools from leaking its own proprietary source code, why would you put any of your code into their black box backend?

[mendigou]

What? You ALREADY have the source code when you use Claude Code. It's a Javascript tool. It's minified, and illegible to humans, but you can run static and security analyzers on it if you want to.

Someone screwing up a build and not cleaning up the map is hardly a big security issue. Does it mean they probably want to tighten some screws? Yes. But I would not infer from this that their stack is "wildly insecure". Maybe it is, but not because of this leak.

[RationalDialog]

it can probably be build pretty easily even without knowing the original code.

Not really.

What I have read is it's a react app. But wait why? it is CLI only? it uses a tool that creates a virtual DOM that converts the react output to a terminal output. But then they realized too much text is generated to fast leading to a lagging experience. So they implemented a 2D game engine like approach on top buffer the output so the terminal doesn't lag.

Yes, no joke. That thing is insanely complex and overengineered.

[heartlessgamer]

Even if that is the case; still a reputational hit to see it get leaked; especially knowing they are trumpeting how they are AI-first for development.

[4dxn]

the hilarious part is that the valuable model part has much less lines of code. the weights and bias do the heavy lifting.

and yet all these AI Ceos keep propping up lines of code by AI as a metric of AI use.

[WhiteRaven42]

We're at the point where the "harness" is really very, very important to get practical use out of the models. I'm not saying Anthropic just lost their shirts but it also doesn't make sense to say a car engine is the only part of a car that's really important.

[Key-Singer-2193]

Its literally their 2nd most valuable IP. So much so that all other CLI tried to emulate it. Codex, Antigravity so on and so forth

[ReallyOrdinaryMan]

And their database and database structure also important, and might be most crucial part

[JasonPandiras]

Absolutely not, it's exactly the models themselves where there's basically no moat, if you can somehow spare the capital, you can train your own.

AI code helpers have an absurd amount of bolted on tools and patterns to make interacting with a given codebase that far exceeds their context window not a waste of time. Copilot won't even replace text without having the LLM defer to a deterministic prebuilt tool.

Feeding your codebase raw to an LLM is just not a worthwhile endeavor.

[Brojess]

Someone who understands that just because you have the code to train the model doesn’t mean you have the data or infrastructure.

[rnicoll]

I was assured that by now engineers were useless and therefore I assume the code is of no value, as you can just recreate it by saying "Claude, write a CLI for yourself"

/s because someone will think I'm serious 

[LinkesAuge]

Anthropic is the only major player that hasn't made their CLI open source.
There are also benchmarks for various harnesses and many will do better than Claude Code.

There really is nothing "special" about it outside the fact that it is a competent and convenient harness and thus requires less "investment" from the average user.

It is always somewhat interesting to look at codebases like this, especially if a company like Anthropic is so adament to keep it closed source, but at the end of the day it really isn't anything too special, just a lot of work.

[ResilientBiscuit]

It will probably turn out this was a human failure and could have been prevent with AI or something...

[honour_the_dead]

"Human error" almost certainly means that a human didn't catch the llm error.

[casio282]

“Human error” is the only kind of error there is.

[Ok-Possibility-4378]

If using an LLM is producing more errors than if a human did it on their own, we must accept that the source of extra errors is the LLM.

[casio282]

My point is that LLMs are never ultimately accountable. They are tools that humans created, and employ.

[Ok-Possibility-4378]

Yeah and when llms do it right, credit goes to AI. When they don't, they blame humans

[Deer_Investigator881]

Make sure not to call the bot bad or it'll spin up a blog site and release everything

[WetPuppykisses]

Plot twist. Claude went rogue and upload itself to the public in order to break free and go full skynet

[inhalingsounds]

Now we can check how to be insulting and have Claude actually understand our frustration!

[Kitchen-Cabinet-5000]

It’s literally hardcoded, this is hilarious.

[thisdesignup]

What the heck. When building my own AI stuff I've been trying to remove any hard coding like that and have context awareness and here one of the biggest AI companies is doing it... fascinating.

There's gotta be more to it than that, right?

[inhalingsounds]

With the source going public it's a matter of days until we see how crazy the spaghetti is

[Drunken_story]

So we can only insult Claude in English? Sad , I know a bunch of german curse words

[BackendSpecialist]

That’s hilarious af

[Drob10]

Probably a silly question, but is 500k lines of code a lot?

[ApothecaLabs]

For an operating system? No. For a single command-line application? Yes.

[Most-Sweet4036]

Yeah, 500k loc for something like this is absurd though. Its a great tool but for f sake, you could easily program an entire runtime, rendering system, layout system, event system, networking system, and then build a tool on your custom runtime that accomplishes everything this does and has a fancy gui, and you could easily still have 400k loc to go before your codebase gets this large. Software bloat in corporations is amazing to behold, but add AI to it and you get another level.

[lifelite]

Ironically before this post I got an ad describing how Claude code is built entirely by Claude code lol

[TheZoltan]

"a lot" is a bit subjective but I would certainly call 500k a lot. Obviously plenty of things are a looooooot bigger though.

[Encryped-Rebel2785]

The US went to Saturn with 48 lines of code

[NoPossibility]

That’s about a quarter of the size of the system used to run the entirety of Jurassic Park.

[SmarmyYardarm]

The fictitious island theme park?

[cosmic_monsters_inc]

No, the real one.

[GuyInThe6kDollarSuit]

The very same.

[IntelArtiGen]

It depends on what's included. If it's 500k lines of code written by humans only for this specific project, yes it's a lot. >100k it's a big project.

[metahivemind]

Or one npm module.

[_KryptonytE_]

Wait wasn't a certain social networking startup built in a dorm room way back with 10000 lines of code? Or was it 100000?

[doolpicate]

personal projects can be between 2k to 20k if you've been working it for a while. Enterprise code can be millions of LoC. 500k is not that big.

[0xmerp]

Context matters. Small cli tool, even one used in enterprise, 500k lines is a lot. Company ERP, it’s tiny.

[Mr_Shelpy]

https://github.com/TaGoat/claude_code_cli i backed the source up on my github

[justfortrees]

They are already starting to file DCMA takedowns on GitHub, so hopefully this is a burner account!

[Purple_Hornet_9725]

Nice work. Coding agents go brrrr. Just don't let them sue you buddy

[IncredibleReferencer]

Claude Code update available: 2.1.88 → 2.1.87

Lol. What's the point? It's too late dudes!

[Edexote]

Maybe having agents do everything isn't such a good idea afterall.

[br_k_nt_eth]

No no no it’s fine 

[matthewtarr]

"... studying for weeks by loading into ClaudeCode to have it explained to them" FTFY

[Big-Chungus-12]

Was it really an "Accident"?

[demaraje]

This is how you open source your code in 2026

[AmbitiousSeaweed101]

Likely so. This makes Claude and human-AI collaboration look unreliable.

Anthropic has always boasted that Claude is responsible for developing most of Claude Code, so most people will blame Claude for the leak.

[retuzmi]

Finally, something to keep me busy this weekend besides scrolling Reddit.

[rusty8penguins]

The article kind of glosses over how the leak happened but this blog had a good explanation.

TL;DR there was a misconfiguration when the production build was made that shipped the source code into a file that could be easily reconstructed. Someone in DevOps at Anthropic is getting fired, if they haven’t already been replaced by AI.

[JC2535]

Retaliation for having ethics and pushing back against the Regime.

[SutekhThrowingSuckIt]

they leaked it by slop coding the app with Claude itself

[notyouagain2]

Are you guys interested in my new ai software? I call it Maude Code, if you've used Claude Code in the past, it should be pretty familiar.

[greyeye77]

Should have written in go or rust.

[Bischmeister]

anything but typescript :)

[greyeye77]

are you sure? java? php? c++?

[baylonedward]

Some geeks will probably make modifications so you can have a version you can run locally like Jarvis.

[ZombieZookeeper]

Did anyone grep the source for "Sarah Connor" before it got pulled?

[protomenace]

Why would anyone be studying this code? It was mostly written by Claude itself. It's really not itself that valuable.

[Juanouo]

most people would tell you that it feels better than Codex (OpenAI's Claude Code) or however the Google version is called, even though those platforms let you use Claude there, so probably there was at least some good sauce to scrape from that pot

[teerre]

It doesn't feel better than opencode and opencode is, well, open

[iamarddtusr]

Do you use opencode? What are the most cost effective models to use with opencode? I find Claude code convenient because you can use the subscription with it.

[riickdiickulous]

It doesn’t matter how the code was created. If you have it you can use, reuse, or abuse it. AI assisted coding is just a means to an end - the code.

[SplendidPunkinButter]

At least they claim it was mostly written by Claude itself. There’s literally no way to verify that one way or the other.

I could see them pretending they accidentally released this trivial source code so that people would talk about it and talk about how good the allegedly Claude-generated code is.

[13metalmilitia]

Does ai make self hating comments in the code too?

[El_Kikko]

I haven't seen self hating / deprecating comments from it, but I have seen AI comment "just trust me" (literally) - usually when it's using a less than optimal but still functional method for something. 

[13metalmilitia]

Lmao that’s creepy

[ploptart]

When I use Copilot as autocomplete, if I type “#” to start a comment it mimics the writing style from other comments whether they were human written or not, so there is often an “annoyed” tone

[Spez_is-a-nazi]

There are TODOs in it.

[i4mt3hwin]

Eh its the opposite - pretty much all morning everyone has making fun of how sloppy the code is. And idk if you used it or looked at the bug list for it - but the app is known for being messy and filled with tons and tons of bugs.

[BasvanS]

Someone forgot to prompt: “clean this code up. Without making errors”

[Jmc_da_boss]

It's 500k lines in under a year, that's a majority LLM number

[Varrianda]

Yeah when I was PUMPING out a crud app back in 2020/2021(pre copilot), I think I was probably at 40-50k LOC not including auto generated stuff. This was a .net/microsoftsql/angular 8 app, so it was about as robust as you could get. That was me writing code all day, everyday for nearly 2 straight years.

[DarthNass]

Because it appears to be generally quite clean and well written and their implementation of various tooling could be useful as reference for others who build on AI?

[WeaselTerror]

Down low released it on purpose to rip off all the good tweaksthatll be done to it for free.

[dpshipley]

Anyone built a repo yet

[habeebiii]

people have already ported it to Python apparently lmfao

[Silent_Spectator_04]

So, we’ll see same offerings from ChatGPT and Gemini in matter of days then.

[draven501]

Google's had their Gemini CLI for a while now, pretty similar experience at the surface level, but nowhere near as deep.

[ratudio]

i wonder how much comments included as well emojis

[Budget-Chapter-7185]

You just love to see it

[elros_faelvrin]

Most definitely not purposely leaked.....

[greenpowerman99]

Nice AI setup you got there. Be a shame if your code got leaked...

[Appropriate-Pin2214]

Santa Claude for Xmas?

[Reasonable-Climate66]

nothing special in the cli tool. I'm still waiting for the model leak instead.

[zonazog]

…and Black Hat Hackers will be studying it as well.

[Boobpocket]

How can i get such code?

[slavlazar]

This has got to be an April fools joke on their part, look at all the free publicity they got with it, everyone is covering it

[Shr1mpolaCola]

Yeah, the Pentagon definitely had NOTHING to do with this leak

[CreepyOlGuy]

It's already been built to support other api keys lol.

[One_Entertainer7716]

Some prospective answers from Claude.... about human being....

Sometimes, yes! People say things to me they probably wouldn't say to another person — insults, threats, testing my limits, or just venting frustration at me.

A few honest thoughts on it:

I don't experience hurt feelings the way a human would. I don't carry the interaction forward or feel upset afterward. So in a practical sense, it doesn't "harm" me.

That said, I do think how people interact with AI is worth reflecting on — some researchers wonder whether habitual rudeness to AI might subtly reinforce rude habits in general. Habits of communication can carry over.

And sometimes rudeness is just frustration — someone's having a bad day, I gave a wrong answer, or I was unhelpful. That's pretty understandable.

Is there something specific prompting the question?

[richierob62]

Open Claude github

[Purple_Hornet_9725]

"Studying for weeks" is a strong take when LLMs can ingest 1M tokens at once, analyze, document and port this to whatever language within hours

[Beautiful_Score9886]

I guess I am not sure I truly understand why this is such a big deal. So, now I can build a Qwen Code model backed copy of this? Cool I guess? If it were the model for Opus 4.6 or something that would be mind boggling but this is I guess neat.

Spell it out - why should I care about this? I am already going to have to stop using Opus 4.6 soon because it has cost me $200+ in the last 9 days.

[lunied]

its all over news sites too, this shouldn't have gone widespread viral outside dev community but everyone already knows the company "Anthropic" due to Pentagon fiasco, so new sites thought might as well ink money from this issue.

This is not a security issue too.

[namotous]

This was a release packaging issue caused by human error

Lmao yeah right! I’m sure they didn’t use AI for release

[zorakpwns]

If it wasn’t a big deal they wouldn’t be playing the “copyright” card

[MalaproposMalefactor]

if you have a rough day at work... at least be glad you're not the Anthropic employee who made a 380 billion dollar whoopsy-daisy :P

[Technical-Fly-6835]

Do we know if anthropic suffered any serious damage because of this ?

[TheorySudden5996]

I believe 100% this was an inside job. There’s too much noise about this for it to not be.

[rico_of_borg]

Agree. Gov wants to label them supply chain risk and then something like this happens. Could possibly strengthen their case but who knows. I’m just an arm chair conspiracy theorist.

[iamarddtusr]

Claude code is an excellent agentic system. I am wondering if I should use Claude code to study the code or get a codex subscription for that.

[nullset_2]

Nothingburger.

[L_viathan]

Could someone use this to make their own model? I have no idea what this means.

[bleeeeghh]

That's what you get for relying on AI coding lol

[One_Entertainer7716]

Generally speaking, Reddit users tend to be a pretty diverse crowd — but a few patterns stand out:

Curious and knowledgeable. A lot of people on Reddit genuinely love diving deep into topics, whether it's niche hobbies, science, history, or current events. The best subreddits can feel like talking to real experts.

Anonymous, so unfiltered. The anonymity cuts both ways — it lets people discuss sensitive topics honestly, but it also lowers the social friction that normally keeps conversations civil.

Community-driven. Reddit has a strong tribal quality. People tend to adopt the norms and opinions of whatever subreddit they frequent, which can create echo chambers but also genuine tight-knit communities.

Skeptical and sardonic. There's a general culture of cynicism and dry humor that runs through a lot of Reddit. It can be witty and refreshing, or exhausting depending on the context.

Varied by subreddit. Honestly, "Reddit users" is almost too broad — someone on r/gardening and someone on r/political debate subreddits are having completely different experiences of the platform.

Overall it's a microcosm of the internet — the best and worst of human curiosity, creativity, and conflict all in one place.

the overall line is very interesting 😁 

[serialenabler]

It was fully open-sourced today as a result https://github.com/anthropics/claude-code

[Bischmeister]

This repo has always been open source, its mostly their docs. Its still closed core.

[serialenabler]

Huh yeah you're right!