Bug

When shell_execute is called with a WorkingDirectory outside the session directory (e.g. ~/.freshdesk-analysis/tickets/601/), ShellTool.ExecuteAsync sets ProcessStartInfo.WorkingDirectory directly without checking if the directory exists.

The code creates the directory only when IsResolvedSessionDirectory() returns true:

// ShellTool.cs lines ~85-100
var resolvedCwd = context.ResolveShellCwd(args.WorkingDirectory);
if (!string.IsNullOrWhiteSpace(resolvedCwd))
{
    if (IsResolvedSessionDirectory(resolvedCwd, context.SessionDirectory))
    {
        Directory.CreateDirectory(resolvedCwd);  // Only here
    }
    psi.WorkingDirectory = resolvedCwd;  // Set regardless
}

When the directory doesn't exist, Process.Start() throws DirectoryNotFoundException, which bubbles up as a generic "Error starting process: ..." message.

Root Cause

ProcessStartInfo.WorkingDirectory requires the path to exist — this is a .NET runtime requirement, not an OS limitation. Forcing agents to create directories via skills before using them as working directories leads to infinite approval-expires loops because the error message doesn't explain why the command failed.

Proposed Fix

Check directory existence before setting WorkingDirectory, and return a helpful error:

if (!string.IsNullOrWhiteSpace(resolvedCwd))
{
    if (IsResolvedSessionDirectory(resolvedCwd, context.SessionDirectory))
    {
        Directory.CreateDirectory(resolvedCwd);
    }
    else if (!Directory.Exists(resolvedCwd))
    {
        return $"Error: Working directory '{resolvedCwd}' does not exist. Create it first (e.g., mkdir -p {resolvedCwd}).";
    }

    psi.WorkingDirectory = resolvedCwd;
}

Impact

• Affects all shell commands with non-session working directories
• Affects PowerShell support when it lands (same code path)
• Agents get stuck in retry loops because the error message doesn't indicate the directory is missing