Clone and cargo build are not enough on Debian or Ubuntu. Unprivileged user namespaces stay off by default there, a sysctl on Debian and an AppArmor switch on Ubuntu 24.04, so the namespace stack in the post never starts. shadow doctor is the check that shows it.
Full-Stack Al Developer | Cybersecurity Enthusiast | Lifelong Learner
I build intelligent, secure, and scalable applications. Passionate about Al, full-stack development, and ethical hacking.
Thanks everyone — these are exactly the kinds of real-world edge cases I want ShadowCLI to be tested against.
The namespace setup requirements need clearer distro-specific documentation; shadow doctor is the starting point, but the install guidance should do more to explain host prerequisites.
The current staging/review model covers filesystem changes made by commands routed through ShadowCLI. It does not capture or roll back external side effects from desktop-control tools, logged-in browsers, or other MCP servers. Those need separate account isolation and action-approval controls.
And the package-cache, OverlayFS, and Git-index points are excellent performance and compatibility items. I’m adding them to the investigation list rather than assuming the current behavior is optimal.
Appreciate the thoughtful feedback — this is how the project gets more robust.
Analyst focused on AI security
Adversarial evaluation of local LLMs, censorship and rejection rate, prompt injection testing, log analysis and defensive automation. Visit: sammideblas.com
Running agent shell commands as an unprivileged user is the cheapest containment there is. The part most people miss is the filesystem: a sandbox that can read the home directory leaks secrets even when the process cannot write anything. Mounting only the workspace and dropping capabilities closes most of the gap.
Full-Stack Al Developer | Cybersecurity Enthusiast | Lifelong Learner
I build intelligent, secure, and scalable applications. Passionate about Al, full-stack development, and ethical hacking.
Absolutely. Least privilege is a great starting point—but filesystem visibility is just as important as write access. A process that can read ~/.ssh, cloud credentials, or .env files can still expose secrets even if it can’t modify them.
That’s why ShadowCLI focuses on staging workspace changes while restricting the filesystem view and applying kernel-level controls to commands explicitly routed through it. The boundary matters: anything executed outside that path isn’t automatically contained.
The separation between command execution and applying changes is what makes this approach particularly interesting. Sandboxing limits what an agent can access, while the review stage gives developers control over what actually reaches the project. One area worth considering is how to handle actions outside the filesystem, such as API calls, browser automation, or MCP tools, since those side effects cannot always be captured or rolled back through a file diff. A layered approach combining OS-level isolation with tool-level permissions could make agent execution much safer.
Full-Stack Al Developer | Cybersecurity Enthusiast | Lifelong Learner
I build intelligent, secure, and scalable applications. Passionate about Al, full-stack development, and ethical hacking.
Agreed—that’s an important next layer. ShadowCLI currently focuses on filesystem and process boundaries for commands explicitly routed through its sandbox; browser, API, and third-party MCP side effects aren’t automatically captured by a file diff or rolled back.
Combining OS-level isolation with narrowly scoped tool permissions is the right direction. The goal is to make the boundary explicit, limit what each tool can do, and keep consequential actions under developer control.
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Does the staging layer also cover tools that never touch the shell, like an MCP server that clicks around a desktop or a logged-in browser? A sent email or a submitted form can't be diffed and rolled back like a file.
For screen-control agents (Auten team here, that's what we build) the closest thing we've found is a separate desktop user holding only the accounts the task needs, plus keeping the client's approval prompt on for send, buy and delete.
Full-Stack Al Developer | Cybersecurity Enthusiast | Lifelong Learner
I build intelligent, secure, and scalable applications. Passionate about Al, full-stack development, and ethical hacking.
Thanks everyone — these are exactly the kinds of real-world edge cases I want ShadowCLI to be tested against.
The namespace setup requirements need clearer distro-specific documentation; shadow doctor is the starting point, but the install guidance should do more to explain host prerequisites.
The current staging/review model covers filesystem changes made by commands routed through ShadowCLI. It does not capture or roll back external side effects from desktop-control tools, logged-in browsers, or other MCP servers. Those need separate account isolation and action-approval controls.
And the package-cache, OverlayFS, and Git-index points are excellent performance and compatibility items. I’m adding them to the investigation list rather than assuming the current behavior is optimal.
Appreciate the thoughtful feedback — this is how the project gets more robust.
Analyst focused on AI security
Adversarial evaluation of local LLMs, censorship and rejection rate, prompt injection testing, log analysis and defensive automation. Visit: sammideblas.com
This maps almost exactly onto the Electron security model — the renderer is the untrusted agent and the main process is the naked bash shell: if you expose ipcRenderer directly, the renderer can ask for anything, and a prompt-based confirmation is no real boundary. The fix is the same one: a contextBridge that exposes only a whitelisted surface, validates every argument, and refuses commands outside the declared permission set. The zero-trust framing is useful here too — assume the untrusted side will exploit whatever you leak, and keep the dangerous primitives (fs, child_process, shell) behind main-process validation rather than trusting the caller.
Full-Stack Al Developer | Cybersecurity Enthusiast | Lifelong Learner
I build intelligent, secure, and scalable applications. Passionate about Al, full-stack development, and ethical hacking.
That’s a strong analogy. A narrow, validated interface is much safer than exposing powerful primitives and relying on prompts for approval.
ShadowCLI applies a similar principle to commands routed through its sandbox: stage workspace changes, restrict access where supported, and keep apply under developer control. The important caveat is that it doesn’t intercept every agent action—native editor tools and external integrations can still operate outside that boundary.
A technologist working in automation. Here I write up what I actually learn building tools, engineering AI agents, and keeping systems running, along with the workflows and habits that stick.
Beyond the unprivileged namespace sysctl, the piece that usually catches people with OverlayFS and coding agents is package caching.
If the agent runs cargo build or npm install inside the scratch layer, the upper directory ends up capturing hundreds of megabytes of downloaded crates and node_modules alongside the actual code diff. Unless you explicitly bind-mount the host global cache read-only into ~/.cargo and ~/.cache, the sandbox re-downloads the world on every attempt, and walking thousands of tiny files across the overlay copy-on-write layer kills disk latency.
The other quirk to watch is git index writes. Some tools rely on hardlinks or atomic renames within the working tree, which can trigger cross-device link errors across overlayfs layers unless the mount specifically enables index and metacopy options.
Full-Stack Al Developer | Cybersecurity Enthusiast | Lifelong Learner
I build intelligent, secure, and scalable applications. Passionate about Al, full-stack development, and ethical hacking.
Thanks everyone — these are exactly the kinds of real-world edge cases I want ShadowCLI to be tested against.
The namespace setup requirements need clearer distro-specific documentation; shadow doctor is the starting point, but the install guidance should do more to explain host prerequisites.
The current staging/review model covers filesystem changes made by commands routed through ShadowCLI. It does not capture or roll back external side effects from desktop-control tools, logged-in browsers, or other MCP servers. Those need separate account isolation and action-approval controls.
And the package-cache, OverlayFS, and Git-index points are excellent performance and compatibility items. I’m adding them to the investigation list rather than assuming the current behavior is optimal.
Appreciate the thoughtful feedback — this is how the project gets more robust.
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Clone and cargo build are not enough on Debian or Ubuntu. Unprivileged user namespaces stay off by default there, a sysctl on Debian and an AppArmor switch on Ubuntu 24.04, so the namespace stack in the post never starts. shadow doctor is the check that shows it.
Thanks everyone — these are exactly the kinds of real-world edge cases I want ShadowCLI to be tested against.
The namespace setup requirements need clearer distro-specific documentation;
shadow doctoris the starting point, but the install guidance should do more to explain host prerequisites.The current staging/review model covers filesystem changes made by commands routed through ShadowCLI. It does not capture or roll back external side effects from desktop-control tools, logged-in browsers, or other MCP servers. Those need separate account isolation and action-approval controls.
And the package-cache, OverlayFS, and Git-index points are excellent performance and compatibility items. I’m adding them to the investigation list rather than assuming the current behavior is optimal.
Appreciate the thoughtful feedback — this is how the project gets more robust.
Running agent shell commands as an unprivileged user is the cheapest containment there is. The part most people miss is the filesystem: a sandbox that can read the home directory leaks secrets even when the process cannot write anything. Mounting only the workspace and dropping capabilities closes most of the gap.
Absolutely. Least privilege is a great starting point—but filesystem visibility is just as important as write access. A process that can read
~/.ssh, cloud credentials, or.envfiles can still expose secrets even if it can’t modify them.That’s why ShadowCLI focuses on staging workspace changes while restricting the filesystem view and applying kernel-level controls to commands explicitly routed through it. The boundary matters: anything executed outside that path isn’t automatically contained.
The separation between command execution and applying changes is what makes this approach particularly interesting. Sandboxing limits what an agent can access, while the review stage gives developers control over what actually reaches the project. One area worth considering is how to handle actions outside the filesystem, such as API calls, browser automation, or MCP tools, since those side effects cannot always be captured or rolled back through a file diff. A layered approach combining OS-level isolation with tool-level permissions could make agent execution much safer.
Agreed—that’s an important next layer. ShadowCLI currently focuses on filesystem and process boundaries for commands explicitly routed through its sandbox; browser, API, and third-party MCP side effects aren’t automatically captured by a file diff or rolled back.
Combining OS-level isolation with narrowly scoped tool permissions is the right direction. The goal is to make the boundary explicit, limit what each tool can do, and keep consequential actions under developer control.
Does the staging layer also cover tools that never touch the shell, like an MCP server that clicks around a desktop or a logged-in browser? A sent email or a submitted form can't be diffed and rolled back like a file.
For screen-control agents (Auten team here, that's what we build) the closest thing we've found is a separate desktop user holding only the accounts the task needs, plus keeping the client's approval prompt on for send, buy and delete.
Thanks everyone — these are exactly the kinds of real-world edge cases I want ShadowCLI to be tested against.
The namespace setup requirements need clearer distro-specific documentation;
shadow doctoris the starting point, but the install guidance should do more to explain host prerequisites.The current staging/review model covers filesystem changes made by commands routed through ShadowCLI. It does not capture or roll back external side effects from desktop-control tools, logged-in browsers, or other MCP servers. Those need separate account isolation and action-approval controls.
And the package-cache, OverlayFS, and Git-index points are excellent performance and compatibility items. I’m adding them to the investigation list rather than assuming the current behavior is optimal.
Appreciate the thoughtful feedback — this is how the project gets more robust.
Agreed. Read access to home dot files leaks even when writes are blocked. A sandbox needs both limits, not one.
This maps almost exactly onto the Electron security model — the renderer is the untrusted agent and the main process is the naked bash shell: if you expose ipcRenderer directly, the renderer can ask for anything, and a prompt-based confirmation is no real boundary. The fix is the same one: a contextBridge that exposes only a whitelisted surface, validates every argument, and refuses commands outside the declared permission set. The zero-trust framing is useful here too — assume the untrusted side will exploit whatever you leak, and keep the dangerous primitives (fs, child_process, shell) behind main-process validation rather than trusting the caller.
That’s a strong analogy. A narrow, validated interface is much safer than exposing powerful primitives and relying on prompts for approval.
ShadowCLI applies a similar principle to commands routed through its sandbox: stage workspace changes, restrict access where supported, and keep apply under developer control. The important caveat is that it doesn’t intercept every agent action—native editor tools and external integrations can still operate outside that boundary.
Beyond the unprivileged namespace sysctl, the piece that usually catches people with OverlayFS and coding agents is package caching.
If the agent runs cargo build or npm install inside the scratch layer, the upper directory ends up capturing hundreds of megabytes of downloaded crates and node_modules alongside the actual code diff. Unless you explicitly bind-mount the host global cache read-only into ~/.cargo and ~/.cache, the sandbox re-downloads the world on every attempt, and walking thousands of tiny files across the overlay copy-on-write layer kills disk latency.
The other quirk to watch is git index writes. Some tools rely on hardlinks or atomic renames within the working tree, which can trigger cross-device link errors across overlayfs layers unless the mount specifically enables index and metacopy options.
Thanks everyone — these are exactly the kinds of real-world edge cases I want ShadowCLI to be tested against.
The namespace setup requirements need clearer distro-specific documentation;
shadow doctoris the starting point, but the install guidance should do more to explain host prerequisites.The current staging/review model covers filesystem changes made by commands routed through ShadowCLI. It does not capture or roll back external side effects from desktop-control tools, logged-in browsers, or other MCP servers. Those need separate account isolation and action-approval controls.
And the package-cache, OverlayFS, and Git-index points are excellent performance and compatibility items. I’m adding them to the investigation list rather than assuming the current behavior is optimal.
Appreciate the thoughtful feedback — this is how the project gets more robust.