Yup it uses Apple Virtualization framework for virtualization. It makes it so I can't use the Claude Cowork within my VMs and that's when I found out it was running a VM, because it caused a nested VM error. All it does is limit functionality, add extra space and cause lag. A better sandbox environment would be Apple seatbelt, which is what OpenAI uses, but even that isn't perfect: https://news.ycombinator.com/item?id=44283454
I don’t have an opinion on how they should handle the nested VMs probably, but I very much disagree that Seatbelt is better. Claude Code (aka `claude`) uses it, and it’s barely good for anything.
Out of curiosity, why are you running Cowork inside a VM in the first place? What does that get you that letting Cowork use its own VM wouldn’t?
It's incredible how many applications abuse disk access.
In a similar fashion, Apple Podcasts app decided to download 120GB of podcasts for random reason and never deleted them. It even showed up as "System Data" and made me look for external drive solutions.
I had the same problem but with a bad time machine backup. ~300GB of my 512GB disk, just labeled the generic "System Data". I lost a day of work over it because I couldn't do Xcode builds and had to do a deep dive into what was going on.
This GitHub issue itself is clearly AI slop. If you’ve been dealing with GitHub issues in the past months it will be obvious, but it’s confirmed at the end:
> Filed via Claude Code
I assume part of it is true, but determining which part is true is the hard part. I’ve lost a lot of time chasing AI-written bug reports that were actually something else wrong with the user’s computer. I’m assuming the claims of “75% faster” and other numbers are just AI junk, but at least someone could verify if the 10GB VM exists.
What's funny is interacting with it in claude code. Claude-desktop-cowork can't do anything about the VM. It creates this 10 GiB VM, but the disk image starts off with something like 6-7 GiB full already, which means any of the cowork stuff you try to do has to fit into the remaining couple of gigs. It's possible to fill it up, and then claude cowork stops working. Because the disk is full. Claude cowork isn't able to fix this problem. It can't even run basic shell commands in the VM, and Opus4.6 is able to tell the user that, but isn't smart enough/empowered to do anything about it.
So contrary to the github issue, my problem is that it's not enough space. So the fix is to navigate to ~/Library/Application\ Support/Claude/vm_bundles, and then ask Claude Code to upsize the disk to a sparse 60 GiB file, giving cowork much more space to work in while not immediately taking up 60 GiB.
Bigger picture, what this teaches me though, is that my knowledge is still useful in guiding the AI to be able to do things, so I'm not obsolete yet!
I believe that employees in Anthropocs use CC to develop CC now.
AI really give much user ability to develop a completed product, but the quality is decreasing. Professional developers will be in demand when the products/features become popular.
First batch of users of new products need to take more responsibility to test the product like a rats in lab
I can’t see how these 1st party products can compete against open source. Why would anyone chose a shit proprietary solution when the free one is better
I literally spent the last 30 mins with DaisyDisk cleaning up stuff in my laptop, I feel HN is reading my mind :)
I also noticed this 10GB VM from CoWork. And was also surprised at just how much space various things seem to use for no particular reason. There doesn't seem to be any sort of cleanup process in most apps that actually slims down their storage, judging by all the cruft.
Even Xcode. The command line tools installs and keeps around SDKs for a bunch of different OS's, even though I haven't launched Xcode in months. Or it keeps a copy of the iOS simulator even though I haven't launched one in over a year.
macbook pro m4 bought last year. worked on so many codes and projects. never hot after closing lid. installed electron claude. closed lid and went to sleep and woke up to macbook that has been hot all night. uninstall claude. problem went away.
i kept telling myself this BUT NEVER ELECTRON AGAIN.
To be fair, ChatGPT seems to be a native app and still somehow managed to continuously burn some 30-40% of CPU on my mac that ended up being attributable to some shimmer animation for two never-loading icons.
Its just another example and just a detail in the broader story: We cannot trust any model provider with any tooling or other non model layer on our machines or our servers. No browsers, no cli, no apps no whatever. There may not be alternatives to frontier models yet, but everything else we need to own as true open source trustable layer that works in our interest. This is the battle we can win.
Also apparently eating 2 GB RAM or so to run an entire virtual machine even if you've disabled Cowork. Not sure which of this is worse. Absolute garbage.
The market for Cowork is normals, getting to tap into a executive assistant who can code. Pros are running their consumer "claws" on a separate Mac Mini. Normals aren't going to do that, and offices aren't going to provision two machines to everyone.
The VM is an obvious answer for this early stage of scaled-up research into collaborative computing.
I concur. I don't want to install libraries on my host machine that I won't use for anything other than development, e.g., Node.js.
On macOS, Lima has been a godsend. I have Claude Code in an image, and I just mount the directory I want the VM to have access to. It works flawlessly and has been a replacement for Vagrant for me for some time. Though, I owe a lot to Vagrant. It was a lifesaver for me back in the day.
labelled "high priority" a month ago. No actual activity by Anthropic despite it being their repo. I'm starting to get the feeling they're not actually very good at this?
Aren't most these people recommending random tools in the github chat for this entry just attempting to exploit naive users? Why would anyone in this day and age follow advice of new users to download new repos or click at random websites when they already attempt to use claude code or cowork?
Hi, Felix from Anthropic here. I work on Claude Cowork and Claude Code.
Claude Cowork uses the Claude Code agent harness running inside a Linux VM (with additional sandboxing, network controls, and filesystem mounts). We run that through Apple's virtualization framework or Microsoft's Host Compute System. This buys us three things we like a lot:
(1) A computer for Claude to write software in, because so many user problems can be solved really well by first writing custom-tailored scripts against whatever task you throw at it. We'd like that computer to not be _your_ computer so that Claude is free to configure it in the moment.
(2) Hard guarantees at the boundary: Other sandboxing solutions exist, but for a few reasons, none of them satisfy as much and allow us to make similarly sound guarantees about what Claude will be able to do and not to.
(3) As a product of 1+2, more safety for non-technical users. If you're reading this, you're probably equipped to evaluate whether or not a particular script or command is safe to run - but most humans aren't, and even the ones who are so often experience "approval fatigue". Not having to ask for approval is valuable.
It's a real trade-off though and I'm thankful for any feedback, including this one. We're reading all the comments and have some ideas on how to maybe make this better - for people who don't want to use Cowork at all, who don't want it inside a VM, or who just want a little bit more control. Thank you!
I accidentally clicked the Claude Cowork button inside the Claude desktop app. I never used it. I didn't notice anything at the time, but a week later I discovered the huge VM file on my disk.
It would be really nice to ask the user, “Are you sure you want to use Cowork, it will download and install a huge VM on your disk.”
> (2) Hard guarantees at the boundary: Other sandboxing solutions exist, but for a few reasons, none of them satisfy as much and allow us to make similarly sound guarantees about what Claude will be able to do and not to.
This is the most interesting requirement.
So all the sandbox solutions that were recently developed all over GitHub, fell short of your expectations?
This is half surprising since many people were using AI to solve the sandboxing issue have claimed to have done so over several months and the best we have is Apple containers.
What were the few reasons? Surely there has to be some strict requirement for that everyone else is missing.
But still having a 10 GB claude.vmbundle doesn't make any sense.
Speaking as a tiny but regulated SMB that's dabbling in skill plugins with Cowork: we strongly appreciate and support this stance. We hope you don't relax your standards, and need you not to. We strongly agree with (1), (2), and (3).
If working outside the sandbox becomes available, Cowork becomes a more interesting exfil vector. A vbox should also be able to be made non-optional — even if MDM allows users to elevate privileges.
We've noticed you're making other interesting infosec tradeoffs too. Your M365 connector aggressively avoids enumeration, which we figured was intentional as a seatbelt for keeping looky-loos in their lane.* Caring about foot-guns goes a long way in giving a sense of you being responsible. Makes it feel less irresponsible to wade in.
In the 'thankful for feedback' spirit, here's a concrete UX gap: we agree approval fatigue matters, and we appreciate your team working to minimize prompts.
But the converse is, when a user rejects a prompt — or it ends up behind a window — there's no clear way to re-trigger. Claude app can silently fail or run forever when it can't spin up the workspace, wasn't allowed to install Python, or was told it can't read M365 data.
Employees who've paid attention to their cyber training (reasonably!) click "No" and then they're stuck without diagnostics or breadcrumbs.
For a CLI example of this done well, see `m365-cli`'s `auth` and `doctor` commands. The tool supports both interactive and script modes through config (backed by a setup wizard):
Similarly, first party MCPs may run but be invisible to Cowork. Show it its own logs and it says "OK, yes, that works but I still can't see it, maybe just copy and paste your context for now." A doctor tool could send the user to a help page or tell them how to reinstall.
Minimal diagnostics for managed machines — running without local admin but able to be elevated if needed — would go a long way for the SMBs that want to deploy this responsibly.
Maybe a resync perms button or Settings or Help Menu item that calls cowork's own doctor cli when invoked?
---
* When given IDs, the connector can read anything the user can anyway. We're able to do everything we need, just had to ship ID signposts in our skill plugin that taps your connector. Preferred that hack over a third party MCP or CLI, thanks to the responsibility you look to be iteratively improving.
Claude Cowork grabs local DNS resolution on macOS which conflicts with secure web gateway aka ZTNA aka SASE products such as Cloudflare Warp which do similar. The work-around is to close Cowork, let Warp grab mDNSResponder's attention first, then restart Claude Desktop, or some similar special ordering sequence. It's annoying, but you could say that about everything having to do with MITM middleboxes.
I would look at how podman for Mac manages this; it is more transparent about what's happening and why it needs a VM. It also lets you control more about how the VM is executed.
> It's a real trade-off though and I'm thankful for any feedback, including this one.
Feedback: If your app is going to use 10GB of storage, tell the user in advance and give them a one-click way to remove it. Just basic manners. Don't pick your nose at the dinner table. It's not hard, just common decency.
> even the ones who are so often experience "approval fatigue". Not having to ask for approval is valuable.
This is by and large a short-term pro for Anthropic. It's often not one for the user, and in the long-term, often barely even for the company. In any case, it's a great example of putting Anthropic priorities above the users'. Which is fine and happens all the time, but in this case just isn't necessary. Similar to the AGENTS.md case. We're on the cusp of a pattern establishing here and that's something you'll want to stop before it's ossified.
agree to this if their target market is only developers
but over 90% of their users are non technical so removing that approval step is the correct move in a product sense.
users install cowork for the magic, 10gb is negligible. these days even steam games are 50gb+ and you care more about the gameplay than the disk space.
Ok, so a lot of this boils down to the fact that this sort of software really wants to be running on linux. For both windows and mac, the only way to (really) do that is creating a VM.
It seems to me that the main issue here is painful disconnects between the VM and the host system. The kernel in the VM wants to manage memory and disk usage and that management ultimately means the host needs to grant the guest OS large blocks of disk and memory.
Is anyone thinking about or working on narrowing that requirement? Like, I may want the 99% of what a VM does, but I really want my host system to ultimately manage both memory and disk. I'd love it if in the linux VM I had a bridge for file IO which interacted directly with the host file system and a bridge in the memory management system which ultimately called the host system's memory allocation API directly and disabled the kernels memory management system.
containers and cgroups are basically how linux does this. But that's a pretty big surface area that I doubt any non-linux system could adopt.
It’s a solved problem in the VM world too. Memory ballooning is a technique where a driver inside the VM kernel cooperates with the hypervisor to return memory back to the host by appearing to consume the memory from the VM. And disk access is even easier; just present a network filesystem to the VM.
I guess it could warn about it but the VM sandbox is the best part of Cowork. The sandbox itself is necessary to balance the power you get with generating code (that's hidden-to-user) with the security you need for non-technical users. I'd go even further and make user grant host filesystem access only to specific folders, and warn about anything with write access: can think of lots of easy-to-use UIs for this.
59 comments
[ 17.2 ms ] story [ 1490 ms ] threadOut of curiosity, why are you running Cowork inside a VM in the first place? What does that get you that letting Cowork use its own VM wouldn’t?
In a similar fashion, Apple Podcasts app decided to download 120GB of podcasts for random reason and never deleted them. It even showed up as "System Data" and made me look for external drive solutions.
> Filed via Claude Code
I assume part of it is true, but determining which part is true is the hard part. I’ve lost a lot of time chasing AI-written bug reports that were actually something else wrong with the user’s computer. I’m assuming the claims of “75% faster” and other numbers are just AI junk, but at least someone could verify if the 10GB VM exists.
So contrary to the github issue, my problem is that it's not enough space. So the fix is to navigate to ~/Library/Application\ Support/Claude/vm_bundles, and then ask Claude Code to upsize the disk to a sparse 60 GiB file, giving cowork much more space to work in while not immediately taking up 60 GiB.
Bigger picture, what this teaches me though, is that my knowledge is still useful in guiding the AI to be able to do things, so I'm not obsolete yet!
AI really give much user ability to develop a completed product, but the quality is decreasing. Professional developers will be in demand when the products/features become popular.
First batch of users of new products need to take more responsibility to test the product like a rats in lab
Try this if you have claude code -- ls -a your home dir and see all the garbage claude creates.
I also noticed this 10GB VM from CoWork. And was also surprised at just how much space various things seem to use for no particular reason. There doesn't seem to be any sort of cleanup process in most apps that actually slims down their storage, judging by all the cruft.
Even Xcode. The command line tools installs and keeps around SDKs for a bunch of different OS's, even though I haven't launched Xcode in months. Or it keeps a copy of the iOS simulator even though I haven't launched one in over a year.
i kept telling myself this BUT NEVER ELECTRON AGAIN.
Might be virtualization woes or something adjacent.
Pondering... Noodling... Some other nonsense...
https://developer.hashicorp.com/vagrant is still a thing.
The market for Cowork is normals, getting to tap into a executive assistant who can code. Pros are running their consumer "claws" on a separate Mac Mini. Normals aren't going to do that, and offices aren't going to provision two machines to everyone.
The VM is an obvious answer for this early stage of scaled-up research into collaborative computing.
On macOS, Lima has been a godsend. I have Claude Code in an image, and I just mount the directory I want the VM to have access to. It works flawlessly and has been a replacement for Vagrant for me for some time. Though, I owe a lot to Vagrant. It was a lifesaver for me back in the day.
Storage should be cheaper, complain about Apple making you pay a premium.
Claude Cowork uses the Claude Code agent harness running inside a Linux VM (with additional sandboxing, network controls, and filesystem mounts). We run that through Apple's virtualization framework or Microsoft's Host Compute System. This buys us three things we like a lot:
(1) A computer for Claude to write software in, because so many user problems can be solved really well by first writing custom-tailored scripts against whatever task you throw at it. We'd like that computer to not be _your_ computer so that Claude is free to configure it in the moment.
(2) Hard guarantees at the boundary: Other sandboxing solutions exist, but for a few reasons, none of them satisfy as much and allow us to make similarly sound guarantees about what Claude will be able to do and not to.
(3) As a product of 1+2, more safety for non-technical users. If you're reading this, you're probably equipped to evaluate whether or not a particular script or command is safe to run - but most humans aren't, and even the ones who are so often experience "approval fatigue". Not having to ask for approval is valuable.
It's a real trade-off though and I'm thankful for any feedback, including this one. We're reading all the comments and have some ideas on how to maybe make this better - for people who don't want to use Cowork at all, who don't want it inside a VM, or who just want a little bit more control. Thank you!
It would be really nice to ask the user, “Are you sure you want to use Cowork, it will download and install a huge VM on your disk.”
This is the most interesting requirement.
So all the sandbox solutions that were recently developed all over GitHub, fell short of your expectations?
This is half surprising since many people were using AI to solve the sandboxing issue have claimed to have done so over several months and the best we have is Apple containers.
What were the few reasons? Surely there has to be some strict requirement for that everyone else is missing.
But still having a 10 GB claude.vmbundle doesn't make any sense.
Sorry for the ask here, but unaware of other avenues of support as the tickets on the Claude Code repo keep getting closed, as it is not a CC issue.
https://github.com/anthropics/claude-code/issues/26457https:...
Claude mangles XML files with <name> as an XML Tag to <n>
https://news.ycombinator.com/item?id=47113548
Speaking as a tiny but regulated SMB that's dabbling in skill plugins with Cowork: we strongly appreciate and support this stance. We hope you don't relax your standards, and need you not to. We strongly agree with (1), (2), and (3).
If working outside the sandbox becomes available, Cowork becomes a more interesting exfil vector. A vbox should also be able to be made non-optional — even if MDM allows users to elevate privileges.
We've noticed you're making other interesting infosec tradeoffs too. Your M365 connector aggressively avoids enumeration, which we figured was intentional as a seatbelt for keeping looky-loos in their lane.* Caring about foot-guns goes a long way in giving a sense of you being responsible. Makes it feel less irresponsible to wade in.
In the 'thankful for feedback' spirit, here's a concrete UX gap: we agree approval fatigue matters, and we appreciate your team working to minimize prompts.
But the converse is, when a user rejects a prompt — or it ends up behind a window — there's no clear way to re-trigger. Claude app can silently fail or run forever when it can't spin up the workspace, wasn't allowed to install Python, or was told it can't read M365 data.
Employees who've paid attention to their cyber training (reasonably!) click "No" and then they're stuck without diagnostics or breadcrumbs.
For a CLI example of this done well, see `m365-cli`'s `auth` and `doctor` commands. The tool supports both interactive and script modes through config (backed by a setup wizard):
https://pnp.github.io/cli-microsoft365/cmd/cli/cli-doctor/
Similarly, first party MCPs may run but be invisible to Cowork. Show it its own logs and it says "OK, yes, that works but I still can't see it, maybe just copy and paste your context for now." A doctor tool could send the user to a help page or tell them how to reinstall.
Minimal diagnostics for managed machines — running without local admin but able to be elevated if needed — would go a long way for the SMBs that want to deploy this responsibly.
Maybe a resync perms button or Settings or Help Menu item that calls cowork's own doctor cli when invoked?
---
* When given IDs, the connector can read anything the user can anyway. We're able to do everything we need, just had to ship ID signposts in our skill plugin that taps your connector. Preferred that hack over a third party MCP or CLI, thanks to the responsibility you look to be iteratively improving.
Feedback: If your app is going to use 10GB of storage, tell the user in advance and give them a one-click way to remove it. Just basic manners. Don't pick your nose at the dinner table. It's not hard, just common decency.
> even the ones who are so often experience "approval fatigue". Not having to ask for approval is valuable.
This is by and large a short-term pro for Anthropic. It's often not one for the user, and in the long-term, often barely even for the company. In any case, it's a great example of putting Anthropic priorities above the users'. Which is fine and happens all the time, but in this case just isn't necessary. Similar to the AGENTS.md case. We're on the cusp of a pattern establishing here and that's something you'll want to stop before it's ossified.
but over 90% of their users are non technical so removing that approval step is the correct move in a product sense.
users install cowork for the magic, 10gb is negligible. these days even steam games are 50gb+ and you care more about the gameplay than the disk space.
hn should really touch more grass.
It seems to me that the main issue here is painful disconnects between the VM and the host system. The kernel in the VM wants to manage memory and disk usage and that management ultimately means the host needs to grant the guest OS large blocks of disk and memory.
Is anyone thinking about or working on narrowing that requirement? Like, I may want the 99% of what a VM does, but I really want my host system to ultimately manage both memory and disk. I'd love it if in the linux VM I had a bridge for file IO which interacted directly with the host file system and a bridge in the memory management system which ultimately called the host system's memory allocation API directly and disabled the kernels memory management system.
containers and cgroups are basically how linux does this. But that's a pretty big surface area that I doubt any non-linux system could adopt.