Please address the comments from this code review:
## Individual Comments

### Comment 1
<location> `src/vcspull/cli/sync.py:225` </location>
<code_context>
+            # Even if the remote branch exists, the lack of upstream tracking
+            # can cause libvcs to construct invalid remote references
+            # Check if there's a remote branch with the same name
+            remote_ref = f"origin/{branch_name}"
+            remote_branch = subprocess.run(
+                ["git", "-C", str(repo_path), "rev-parse", "--verify", remote_ref],
+                capture_output=True,
</code_context>

<issue_to_address>
Assumes 'origin' as remote; may not be correct for all repos.

This approach may fail in repositories where the remote is not named 'origin'. Allow configuring the remote name or detect it automatically.

Suggested implementation:

```python
            # Even if the remote branch exists, the lack of upstream tracking
            # can cause libvcs to construct invalid remote references
            # Check if there's a remote branch with the same name

            # Detect remote name automatically
            remote_name_proc = subprocess.run(
                ["git", "-C", str(repo_path), "remote"],
                capture_output=True,
                text=True,
                timeout=5,
                check=False,
            )
            remote_name = "origin"
            if remote_name_proc.returncode == 0:
                remotes = remote_name_proc.stdout.strip().splitlines()
                if remotes:
                    remote_name = remotes[0]  # Use the first remote found

            remote_ref = f"{remote_name}/{branch_name}"
            remote_branch = subprocess.run(
                ["git", "-C", str(repo_path), "rev-parse", "--verify", remote_ref],
                capture_output=True,

```

If you want to allow the remote name to be configured (e.g., via a function argument or environment variable), you should:
1. Add a parameter to the relevant function to accept `remote_name`, defaulting to None.
2. If `remote_name` is provided, use it; otherwise, detect as above.
3. Optionally, check for an environment variable (e.g., `VCS_REMOTE_NAME`) before falling back to detection.

You may need to propagate this parameter through function calls or configuration.
</issue_to_address>

### Comment 2
<location> `src/vcspull/cli/sync.py:246` </location>
<code_context>
+        return False  # Git command failed or not available
+
+
+def handle_branch_error(repo_dict: dict[str, t.Any]) -> None:
+    """Handle branch-related errors by showing helpful instructions.
+
</code_context>

<issue_to_address>
Consider logging errors instead of only printing to stderr.

Using the logger will improve error traceability and make integration with monitoring tools easier.

Suggested implementation:

```python
import logging
import subprocess
import sys
import typing as t
from copy import deepcopy

logger = logging.getLogger(__name__)

```

```python
def handle_branch_error(repo_dict: dict[str, t.Any]) -> None:
    """Handle branch-related errors by showing helpful instructions.

    logger.error(
        "Branch-related error detected for repository: %s\n"
        "Please check your branch configuration and ensure upstream tracking is set correctly.",
        repo_dict.get("name", "<unknown>")
    )

```
</issue_to_address>

### Comment 3
<location> `tests/test_sync.py:322` </location>
<code_context>
+def test_check_branch_state(tmp_path: pathlib.Path) -> None:
</code_context>

<issue_to_address>
Consider adding tests for detached HEAD and missing repo path edge cases.

Tests currently cover typical branch states but not detached HEAD or missing 'path' in repo_dict. Including these cases will improve coverage and error handling.
</issue_to_address>

### Comment 4
<location> `tests/test_sync.py:411` </location>
<code_context>
+def test_handle_branch_error(
</code_context>

<issue_to_address>
Test only checks first 5 branches; consider parametrizing for different branch counts.

Parametrize the test to cover scenarios with fewer, exactly, and more than 5 branches to improve coverage.

Suggested implementation:

```python
import pytest

@pytest.mark.parametrize(
    "branches",
    [
        ["main", "dev"],  # fewer than 5
        ["main", "dev", "feature1", "feature2", "feature3"],  # exactly 5
        ["main", "dev", "feature1", "feature2", "feature3", "hotfix"],  # more than 5
    ],
)
def test_handle_branch_error(
    branches,
    tmp_path: pathlib.Path,
    capsys: pytest.CaptureFixture[str]
) -> None:
    """Test that handle_branch_error shows helpful error message for different branch counts."""
    repo_dict = {
        "name": "test-repo",
        "url": "[email protected]:user/repo.git",
        "path": tmp_path / "test-repo",
    }

    # Create a mock git directory for testing
    # Simulate branches in the repo
    # You may need to adjust the following lines to fit your repo setup logic
    repo_path = repo_dict["path"]
    repo_path.mkdir(parents=True, exist_ok=True)
    (repo_path / ".git").mkdir()

    # Simulate branch list
    # If your code uses subprocess to get branches, you may need to patch subprocess.run
    # For now, we just show how to use the branches variable in the test
    # Example: pass branches to the function or mock the function that lists branches

    # ... rest of your test logic here, using the branches variable ...

```

You will need to adjust the test logic to use the `branches` variable, depending on how your code fetches branch names (e.g., patching subprocess or passing directly). If you use subprocess to get branches, consider patching it to return the `branches` list for each test case.
</issue_to_address>

## Security Issues

### Issue 1
<location> `src/vcspull/cli/sync.py:262` </location>

<issue_to_address>
**security (python.lang.security.audit.dangerous-subprocess-use-audit):** Detected subprocess function 'run' without a static string. If this data can be controlled by a malicious actor, it may be an instance of command injection. Audit the use of this call to ensure it is not controllable by an external resource. You may consider using 'shlex.escape()'.

*Source: opengrep*
</issue_to_address>