[BUG] Sandbox doesn't work when ~/.claude/settings.json is read-only symlink to nix-store

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

bwrap fails to setup because it can't write to ~/.claude/settings/json

contents:

! ls -la  ~/.claude/settings.json
  ⎿  lrwxrwxrwx 1 arian users 84 Apr 23 21:43 /home/arian/.claude/settings.json -> /nix/store/9gfvbr7vmj2vsqisakvi9vxs7p3i0lzl-home-manager-files/.claude/settings.json

! cat ~/.claude/settings.json
  ⎿  {
       "$schema": "https://json.schemastore.org/claude-code-settings.json",
       "permissions": {
         "allow": [
           "Bash(jj log)",
           "Bash(jj st)",
           "Bash(jj diff)",
     "Bash(jj root)"
         ],
         "deny": [
     "Bash(git *)"
         ]
       },
       "sandbox": {
         "enabled": true,
         "failIfUnavailable": true,
         "filesystem": {
           "allowRead": [
             ".",
             "/nix/store",
     "/nix/var/nix/daemon-socket/socket"
           ],
           "allowWrite": [
             ".",
     "/nix/var/nix/daemon-socket/socket"
           ],
           "denyRead": [
     "/"
           ],
           "denyWrite": [
     "/"
           ]
         },
         "network": {
           "allowAllUnixSockets": true,
           "allowedDomains": [
             "cache.nixos.org",
     "channels.nixos.org"
           ]
         }
       }
     }

What Should Happen?

It shouldn't fail.

Error Messages/Logs

● Bash(curl -s https://github.com | head -5)
  ⎿  Error: Exit code 1
     bwrap: Can't create file at /home/arian/.claude/settings.json: No such file or directory

● Blocked by the sandbox — bwrap (bubblewrap) denied the network access. That confirms the distinction: local Bash calls are sandboxed, WebFetch is not.

❯ nah it fails for antoehr reason

● Right — the actual error is bwrap: Can't create file at /home/arian/.claude/settings.json: No such file or directory. The bubblewrap sandbox setup itself is failing
  because /home/arian/.claude/settings.json doesn't exist, which bwrap needs to set up the sandbox. That's the real blocker, not a network rule for github.com.

! ls ~/.claude/settings.json
  ⎿  /home/arian/.claude/settings.json

! ls -la  ~/.claude/settings.json
  ⎿  lrwxrwxrwx 1 arian users 84 Apr 23 21:43 /home/arian/.claude/settings.json -> /nix/store/9gfvbr7vmj2vsqisakvi9vxs7p3i0lzl-home-manager-files/.claude/settings.json

❯ ● Right — the actual error is bwrap: Can't create file at /home/arian/.claude/settings.json: No such file or directory. The bubblewrap sandbox setup itself is
  failing
    because /home/arian/.claude/settings.json doesn't exist, which bwrap needs to set up the sandbox. That's the real blocker, not a network rule for github.com.

  ! ls ~/.claude/settings.json
    ⎿  /home/arian/.claude/settings.json

  ! ls -la  ~/.claude/settings.json
    ⎿  lrwxrwxrwx 1 arian users 84 Apr 23 21:43 /home/arian/.claude/settings.json ->
  /nix/store/9gfvbr7vmj2vsqisakvi9vxs7p3i0lzl-home-manager-files/.claude/settings.json
   but it does

● The file exists but it's a symlink into /nix/store (read-only). bwrap likely tries to bind-mount or create an overlay for that path as part of sandbox setup, but
  can't because the target is in the immutable Nix store. That's what causes the failure.

Steps to Reproduce

Make settings.json a read-only symlink to /nix/store path.

This happens when using home-manager

{ pkgs, lib, ... }:
{
  programs.claude-code = {
    enable = true;
    settings = {
      sandbox = {
        enabled = true;
        failIfUnavailable = true;
        filesystem = {
          denyWrite = [ "/" ];
          denyRead = [ "/" ];
          allowRead = [
            "."
            "/nix/store"
            "/nix/var/nix/daemon-socket/socket"
          ];
          allowWrite = [
            "."
            "/nix/var/nix/daemon-socket/socket"
          ];
        };
        network = {
          allowUnixSockets = lib.mkIf pkgs.stdenv.hostPlatform.isDarwin [ "/nix/var/nix/daemon-socket/socket" ];
          allowAllUnixSockets = pkgs.stdenv.hostPlatform.isLinux;
          allowedDomains = [
            "cache.nixos.org"
            "channels.nixos.org"
          ];
        };
      };
      permissions = {
        deny = [ "Bash(git *)" ];
        allow = [
          "Bash(jj log)"
          "Bash(jj st)"
          "Bash(jj diff)"
          "Bash(jj root)"
        ];
      };
    };
  };
}

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.112 (Claude Code)

Platform

Anthropic API

Operating System

Other Linux

Terminal/Shell

Other

Additional Information

_No response_