Antigravity IDE Terminal Sandbox: Fixing Windows ACL Access Denied Errors in Agentic Workflows
Antigravity IDE Terminal Sandbox: Fixing Windows ACL Access Denied Errors in Agentic Workflows
Your agent was three steps into a file refactor, moving configs and rewriting imports, when the terminal panel just stopped. Access is denied. No stack trace, no helpful hint, just a dead task and a spinning cursor. You right-click, run Antigravity as administrator, retry the exact same prompt — and it fails again.
If that sounds familiar, you're not dealing with a permissions problem you can brute-force away. You're dealing with at least three separate Windows security layers that all happen to produce the same error text. This guide walks through what's actually going on under the hood, how to tell the causes apart, and how to fix each one properly instead of guessing.
Access Deniedin Antigravity's terminal on Windows usually comes from one of three unrelated layers: NTFS ACL/ownership, process Integrity Level (MIC), or VS Code's Workspace Trust boundary.- Diagnose first with
icacls,Get-Acl, or Process Monitor — don't just re-run as admin and hope. - Fix with
takeown+icacls /grantfor ownership issues, or add Antigravity to Controlled Folder Access exceptions if Defender is the blocker.
When Your Agent Freezes Mid-Task: The "Access Denied" Wall
Antigravity, Google's Gemini 3-powered agentic IDE launched on November 18, 2025, runs on a VS Code fork architecture with three surfaces: Editor, Terminal, and Browser. The whole pitch is that agents handle terminal commands and file operations autonomously, so you can hand off a task and walk away.
That works beautifully on macOS and Linux demos. On Windows, it runs straight into a security model that macOS/Linux users rarely think about: NTFS discretionary access control lists layered on top of process integrity levels, layered on top of the editor's own workspace trust logic. When an agent tries to touch a file it doesn't have clearance for, all three layers can throw the exact same Access is denied string.
Running as administrator "fixes" some of these cases by accident, which is exactly why it's a bad habit. It masks the real cause and violates least-privilege practice at the same time. If your agent needs admin rights to move a file inside your own project folder, something upstream is misconfigured — not your account.
Three Root Causes Behind the Same Error Message
Windows doesn't have one gatekeeper. It has several, and they don't share a common log format, so the same error text can mean completely different things depending on which layer tripped.
NTFS DACL and ownership mismatches are the most common cause. Windows objects carry a Discretionary ACL made of Access Control Entries (ACEs). Here's the part that catches people off guard: an explicit Deny ACE always wins over an inherited Allow ACE, even if the Allow looks like it should apply. An agent that only checks the parent folder's permissions and assumes the child file inherited them cleanly can walk straight into this.
Mandatory Integrity Control (MIC) is a separate mechanism entirely, and it's the one most developers have never had to think about. Windows assigns integrity levels — Low, Medium, High, System — to processes and objects, independent of the DACL. A process running at Low Integrity is blocked from writing to Medium-or-higher objects even if the DACL grants it Full Control. If Antigravity's terminal or extension host process spawns with a restricted token (a common pattern in Electron/Chromium-based apps forked from VS Code), you get a scenario where the permissions "look fine" in every dialog box, yet the write still fails.
Workspace Trust boundaries are an application-level restriction, not an OS one. VS Code's Workspace Trust feature limits what extensions can do in folders the user hasn't explicitly marked as trusted. Since Antigravity forked this codebase, the same boundary applies. An agent trying to reach outside the workspace root — your home directory, a mapped drive, a sibling project folder — can get blocked here, and it has nothing to do with NTFS at all.
Here's how to tell them apart before you touch anything:
| Cause | Typical Trigger | Where to Look | Quick Tell |
|---|---|---|---|
| NTFS DACL / Ownership | Agent moves/renames files created by another user or process | icacls, file Properties → Security tab |
Owner field shows a different account than the one running Antigravity |
| Integrity Level (MIC) | Agent's terminal writes to a Medium/High integrity object from a Low-integrity process | Process Monitor (procmon), Get-Process token inspection |
DACL shows Full Control, yet write still fails |
| Workspace Trust | Agent tries to touch a path outside the opened workspace folder | Antigravity's trust banner/notification | Error appears instantly, no OS dialog, only on out-of-scope paths |
Note that Antigravity's own internal sandbox implementation — whether it deliberately spawns terminal processes at a lowered integrity level, and how it isolates ACLs per process — isn't publicly documented by Google as of this writing. What follows is grounded in documented Windows OS mechanisms, applied to the symptoms this architecture is known to produce.
Diagnosing the Real Cause Before You Fix Anything
Skip the guesswork. Run these three checks in order, and stop as soon as one of them explains the failure.
Step 1 — Check effective NTFS permissions.
icacls "C:\Projects\your-repo\src\config.ts"Look at the output for explicit (DENY) entries and confirm the owner matches the account Antigravity is running under. If the owner is BUILTIN\Administrators but you're running as a standard user, that's your answer.
Step 2 — Cross-check with PowerShell's ACL cmdlet for a more structured view:
Get-Acl "C:\Projects\your-repo\src\config.ts" | Format-ListThis is useful when icacls output gets long and you just want the owner and access rules side by side.
Step 3 — If permissions look correct but the write still fails, pull out Process Monitor.
Download Sysinternals Process Monitor, filter by:
Process NamecontainsAntigravity(or the underlyingCode.exe-derived binary)ResultisACCESS DENIED
Procmon will show you the exact operation (WriteFile, CreateFile, etc.) and the path at the moment of failure. If the DACL check in Step 1 showed no explicit deny, but procmon still logs ACCESS DENIED on a write operation, you're very likely looking at an integrity-level conflict rather than a permissions one.
Step 4 — Rule out Windows Defender.
Open Event Viewer and check under Applications and Services Logs → Microsoft → Windows → Windows Defender → Operational for Event ID 5007. This specifically flags Controlled Folder Access blocks, and it's easy to miss because it doesn't surface as a Windows dialog — it just silently fails the write and logs it.
Fixing It: ACL, Ownership, and Defender Exceptions
Once you know which layer is blocking you, the fix is usually a few commands, not a system reinstall.
If it's an ownership/ACL problem, reclaim ownership first, then grant recursive permissions:
takeown /f "C:\Projects\your-repo" /r /d y
icacls "C:\Projects\your-repo" /grant "YourUsername:(OI)(CI)F" /TThe (OI) and (CI) flags matter here — they mean Object Inherit and Container Inherit, which is what makes the permission apply to every file and subfolder underneath, not just the top-level directory. Skipping /T or these flags is the most common reason people think this command "didn't work."
If it's Controlled Folder Access blocking Antigravity, add the executable as an allowed app:
- Open Windows Security → Virus & threat protection → Manage ransomware protection.
- Under Controlled folder access, click Allow an app through Controlled folder access.
- Browse to the Antigravity installation path and add the main executable.
This is specifically needed if your project lives inside Documents, Desktop, or another protected folder — which, if you're syncing your repo through OneDrive, is more common than you'd think.
Why "run as administrator" isn't a real fix: admin elevation can bypass some DACL checks, but it doesn't touch Workspace Trust logic, and it doesn't reliably resolve Controlled Folder Access blocks either, since Defender evaluates by application identity, not privilege level. You end up with a broader attack surface and a problem that resurfaces the moment you close and reopen the IDE without elevation.
Designing Safer Agentic Workflows on Windows
The fixes above solve today's error. The better move is preventing the conflict from ever showing up.
Keep your workspace root as a single, purpose-built project directory, and set ownership correctly the moment you create it — not after the agent has already failed twice. If you're cloning repos across drives or from a shared network location, run icacls once upfront to confirm the account running Antigravity actually owns the tree.
Don't let agents reach outside the workspace boundary. If a task genuinely needs to touch a file in your home directory or another drive, do that step manually rather than widening the agent's effective scope. This isn't just about avoiding errors — it's the same least-privilege principle that governs any automation with filesystem write access, agentic or not.
Conclusion & Next Steps
Access Denied in Antigravity's terminal isn't one bug with one fix. It's three different security layers — NTFS ACLs, integrity levels, and Workspace Trust — that happen to share an error message. Diagnosing which one you're actually facing, with icacls, Get-Acl, or Process Monitor, will save you from cycles of "run as admin, still fails, reboot, still fails."
If you're comparing Antigravity's workflow quirks against a standard VS Code setup, it's worth reading through other Antigravity troubleshooting writeups on workspace configuration before you commit to a full agentic pipeline. And since Antigravity's internal sandbox behavior isn't fully documented, it's worth keeping an eye on the official GitHub Issues and community channels — this is exactly the kind of thing that gets patched quietly between releases.
icacls로 소유권을 확인하고 Process Monitor로 실제 실패 지점을 캡처하세요. 원인 계층(ACL / 무결성 수준 / 워크스페이스 신뢰)을 정확히 파악한 뒤 해당 해결책만 적용하면, 같은 에러가 재발하는 악순환을 끊을 수 있습니다.
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