Add shell server MCP image for Harbor integration

[dzorlu]

Summary

Add a new MCP server that provides bash execution and file operations, enabling Harbor to use Fleet environments for agent evaluation.

Tools provided

Tool	Description
bash_exec	Execute bash commands with timeout support
file_read	Read file contents (text or base64 for binary)
file_write	Write content to files (text or base64)
file_list	List directory contents
file_delete	Delete files or empty directories

Files

• fleet/agent/shell_server/main.py - MCP server entry point
• fleet/agent/shell_server/tools.py - Tool definitions
• fleet/agent/shell_server/Dockerfile - Container image
• fleet/agent/shell_server/requirements.txt - Dependencies

Usage

This enables Harbor's BaseEnvironment interface to work with Fleet:

# Harbor FleetEnvironment uses these tools:
await exec("ls -la")           # -> bash_exec
await upload_file(...)         # -> file_write  
await download_file(...)       # -> file_read

Related

• Harbor PR: Add Fleet cloud environment integration harbor#1

🤖 Generated with Claude Code

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{Bugbot Autofix is OFF. To automatically fix reported issues with Cloud Agents, enable Autofix in the Cursor dashboard.}

[cursor]

Unreachable PermissionError handler due to OSError ordering

Medium Severity

In file_delete, the except OSError handler on line 229 is placed before the except PermissionError handler on line 233. Since PermissionError is a subclass of OSError, permission errors will always be caught by the OSError block first, making the PermissionError handler dead code. This means permission-denied deletions won't get the specific warning log or the user-friendly "Permission denied" message — they'll fall through the generic OSError path instead. The other tools (file_read, file_write, file_list) all correctly place PermissionError before their broader exception handlers.