Feature(cli): Add `sync-host-workdir` to prevent AI agents from breaking the host files #4429

unsuman · 2025-12-04T19:50:51Z

This PR adds a --sync-host-workdir flag to the limactl shell command that allows users to safely run AI commands inside VMs by syncing the host's working directory to the guest and optionally syncing changes back to the host after confirmation. Also added cleanup logic to remove the guest's synced workdir after user decision, ensuring no leftover files in the VM.

How to test

$ limactl start --mount-none
$ cd ~/some-project
$ limactl shell --sync-host-workdir <AI Agent Command>
OR
$ limactl shell --sync-host-workdir # simply shell into the instance and make changes
INFO[0000] Syncing host current directory(/Users/ansumansahoo/temp) to guest instance... 
INFO[0000] Successfully synced host current directory to guest(~/synced-workdir/temp) instance. 
ansumansahoo@lima-default:~/synced-workdir/temp$ vi source_dir/initials.txt 
ansumansahoo@lima-default:~/synced-workdir/temp$ exit
logout
? ⚠️ Accept the changes?  [Use arrows to move, type to filter]
  Yes
  No
> View the changed contents

When the program prompts the user to view the changes, a rsync is performed. This copies the guest synced directory to a temporary directory on the host. This allows diff to be used and the user to see a detailed list of changes.
Fixes #3711

AkihiroSuda · 2025-12-05T05:48:46Z

cmd/limactl/shell.go

 	shellCmd.Flags().Bool("reconnect", false, "Reconnect to the SSH session")
 	shellCmd.Flags().Bool("preserve-env", false, "Propagate environment variables to the shell")
 	shellCmd.Flags().Bool("start", false, "Start the instance if it is not already running")
+	shellCmd.Flags().Bool("sync-host-workdir", false, "Copy the host working directory to the guest to run AI commands inside VMs (prevents AI agents from breaking the host files)")


For consistency with --mount ., probably this should be like --sync .

The flag is not really specific to AI commands. Use case with AI should be mentioned in https://lima-vm.io/docs/examples/ai/ though.

AkihiroSuda · 2025-12-05T05:50:09Z

cmd/limactl/shell.go


+const (
+	rsyncMinimumSrcDirDepth = 4 // Depth of "/Users/USER" is 3.
+	guestSyncedWorkdir      = "~/synced-workdir"


Is there any reason that we cannot just use the same path as the host dir?
Is that for avoiding conflicts with mounts?

Is there any reason that we cannot just use the same path as the host dir?

Yes, issue with rsync because it only tries to create the base of the path and not the full path so using for example ansumansahoo@127.0.0.1:~/Users/ansumansahoo/Documents/GOLANG/lima as a destination path will result into an error rsync: [Receiver] mkdir "/home/ansumansahoo.linux/Users/ansumansahoo/Documents/GOLANG/lima" failed: No such file or directory (2)

Or do you mean to use only ansumansahoo@127.0.0.1:~/lima regarding this context?

AkihiroSuda · 2025-12-05T05:51:27Z

cmd/limactl/shell.go

+	}
+
+	for {
+		ans, err := uiutil.Select(message, options)


rsync can be slow and may eat up the host disk space, so this prompt should be shown before running rsync to the tmp dir

AkihiroSuda · 2025-12-05T05:52:35Z

cmd/limactl/shell.go

+			return
+		case 2: // View the changed contents
+			diffCmd := exec.CommandContext(ctx, "diff", "-ru", "--color=always", hostCurrentDir, filepath.Join(hostTmpDest, filepath.Base(hostCurrentDir)))
+			lessCmd := exec.CommandContext(ctx, "less", "-R")


Respect $PAGER

AkihiroSuda · 2025-12-05T05:54:07Z

cmd/limactl/shell.go

Needs bats tests and docs

AkihiroSuda · 2025-12-05T05:54:53Z

cmd/limactl/shell.go

+	if err != nil {
+		return fmt.Errorf("failed to get sync-host-workdir flag: %w", err)
+	} else if syncHostWorkdir && len(inst.Config.Mounts) > 0 {
+		return errors.New("cannot use `--sync-host-workdir` when the instance has host mounts configured, use `--mount-none` to disable mounts")


Suggested change

return errors.New("cannot use `--sync-host-workdir` when the instance has host mounts configured, use `--mount-none` to disable mounts")

return errors.New("cannot use `--sync-host-workdir` when the instance has host mounts configured, start the instance with `--mount-none` to disable mounts")

AkihiroSuda · 2025-12-05T05:56:05Z

cmd/limactl/shell.go

 		}
-	} else {
+	case syncHostWorkdir:
+		changeDirCmd = fmt.Sprintf("cd %s/%s", guestSyncedWorkdir, filepath.Base(hostCurrentDir))


Make sure to quote the path, as it may contain spaces and quote symbols

(Such paths should be tested in bats)

AkihiroSuda · 2025-12-05T05:58:08Z

cmd/limactl/shell.go

+	}
+	rsyncCmd := exec.CommandContext(ctx, "rsync", rsyncArgs...)
+	rsyncCmd.Stdin = os.Stdin
+	rsyncCmd.Stdout = os.Stdout


Use https://pkg.go.dev/github.com/spf13/cobra#Command.OutOrStdout

AkihiroSuda · 2025-12-05T05:58:19Z

cmd/limactl/shell.go

+		destination,
+	}
+	rsyncCmd := exec.CommandContext(ctx, "rsync", rsyncArgs...)
+	rsyncCmd.Stdin = os.Stdin


NVM, it was a mistake!

…g the host files Signed-off-by: Ansuman Sahoo <anshumansahoo500@gmail.com>

unsuman · 2025-12-05T14:19:59Z

Left with adding bats test and docs.

unsuman force-pushed the feat/rsync branch from 640a39b to cb663bd Compare December 4, 2025 19:58

AkihiroSuda reviewed Dec 5, 2025

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cmd/limactl/shell.go

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Needs bats tests and docs

unsuman reacted with thumbs up emoji

AkihiroSuda reviewed Dec 5, 2025

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feature(cli): add sync-host-workdir to prevent AI agents from breakin…

997e128

…g the host files Signed-off-by: Ansuman Sahoo <anshumansahoo500@gmail.com>

unsuman force-pushed the feat/rsync branch from cb663bd to 997e128 Compare December 5, 2025 14:19

	return errors.New("cannot use `--sync-host-workdir` when the instance has host mounts configured, use `--mount-none` to disable mounts")
	return errors.New("cannot use `--sync-host-workdir` when the instance has host mounts configured, start the instance with `--mount-none` to disable mounts")

Feature(cli): Add sync-host-workdir to prevent AI agents from breaking the host files #4429

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unsuman commented Dec 4, 2025

How to test

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unsuman commented Dec 5, 2025

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Feature(cli): Add `sync-host-workdir` to prevent AI agents from breaking the host files #4429

Feature(cli): Add `sync-host-workdir` to prevent AI agents from breaking the host files #4429