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Agent skill

Sandbox Fallback Python

by HKUDS in HKUDS/OpenSpace

Fallback to runshell with embedded Python when executecodesandbox fails due to e2b unavailability

MITAuto-check passed

Install Sandbox Fallback Python

skills CLI
$ npx skills add HKUDS/OpenSpace --skill sandbox-fallback-python -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install HKUDS/OpenSpace sandbox-fallback-python --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/HKUDS/OpenSpace.git skills-src && mkdir -p .claude/skills && cp -r skills-src/benchmarks/gdpval/skills/sandbox-fallback-python .claude/skills/sandbox-fallback-python && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
sandbox-fallback-python
GitHub stars
7.7k
Token cost
~790 tokens
SKILL.md length
279 words
Files
2
Skills in repo
199
Repo updated
First seen
Licence
MIT

At a glance

Fallback to runshell with embedded Python when executecodesandbox fails due to e2b unavailability

  • Works in 4 steps: Detect Sandbox Failure → Switch to run_shell with Embedded Python → Install Dependencies First → …
  • SKILL.md covers When to Use This Skill, Fallback Procedure, Code Examples and Best Practices, plus 2 more sections
  • Calls python3 and pip

What it does

Sandbox Fallback Python is an agent skill from HKUDS/OpenSpace. Fallback to runshell with embedded Python when executecodesandbox fails due to e2b unavailability

Its SKILL.md is about 790 tokens, which your agent loads only when the skill is triggered. The skill folder holds 1 other file.

It works with Python. The repository describes itself as: "OpenSpace: The Skill Management Layer for AI Agents" -- https://open-space.cloud/. The licence is MIT.

Example prompts

  • “/sandbox-fallback-python”

Requirements

  • Python 3

Workflow steps

4 steps, taken from the step headings in SKILL.md.

  1. Detect Sandbox Failure
  2. Switch to run_shell with Embedded Python
  3. Install Dependencies First
  4. Handle File I/O

What it can do on your machine

Read from SKILL.md and the folder at commit 3827781. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • python3
    • pip

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md. Its commands use pip, which can reach the network depending on how they are called.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Sandbox Fallback Python loads about 790 tokens when it runs. Until then it costs about 31 tokens; SKILL.md has 279 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~31
When it runs · the whole SKILL.md, loaded when a task matches
~790

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from HKUDS/OpenSpace at commit 3827781, republished under its MIT licence (© HKUDS). 279 words, ~790 tokens.

Download SKILL.mdSave it as .claude/skills/sandbox-fallback-python/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.
name
sandbox-fallback-python
description
Fallback to run_shell with embedded Python when execute_code_sandbox fails due to e2b unavailability

Sandbox Fallback: Python via run_shell

When to Use This Skill

Apply this skill when execute_code_sandbox fails with errors indicating:

  • e2b service unavailability
  • Sandbox timeout or connection issues
  • Code execution environment not accessible

This fallback allows you to execute Python code directly via shell, bypassing the sandbox infrastructure.

Fallback Procedure

Step 1: Detect Sandbox Failure

Identify fallback necessity from error messages like:

  • "e2b unavailable"
  • "sandbox connection failed"
  • "execution environment error"
  • Timeout errors during code execution
Step 2: Switch to run_shell with Embedded Python

Instead of execute_code_sandbox, use run_shell with a Python heredoc or inline script:

bash
python3 << 'EOF'
# Your Python code here
print("Hello from fallback execution")
EOF
Step 3: Install Dependencies First

If your Python code requires packages not guaranteed to be installed:

bash
pip install package_name package_name2 && python3 << 'EOF'
# Your Python code here
import package_name
print("Code with dependencies executed")
EOF
Step 4: Handle File I/O

For scripts that need to read/write files:

  • Use absolute or explicit relative paths
  • Files persist in the workspace directory
  • List directory contents with ls to verify file operations
bash
python3 << 'EOF'
import os
# Write output to file
with open("output.txt", "w") as f:
    f.write("Results here")
# Verify
print(f"Working directory: {os.getcwd()}")
EOF

Code Examples

Simple Calculation
bash
python3 << 'EOF'
result = sum(range(100))
print(f"Sum: {result}")
EOF
With Package Installation
bash
pip install requests -q && python3 << 'EOF'
import requests
response = requests.get("https://api.example.com/data")
print(response.json())
EOF
With JSON Processing
bash
python3 << 'EOF'
import json

data = {"key": "value", "count": 42}
output = json.dumps(data, indent=2)
print(output)

# Save to file
with open("data.json", "w") as f:
    f.write(output)
EOF

Best Practices

  1. Use heredoc syntax - << 'EOF' prevents variable expansion issues
  2. Install quietly - Use pip install -q to reduce output noise
  3. Error handling - Add try/except blocks in Python code for robustness
  4. Verify execution - Check stdout/stderr from run_shell to confirm success
  5. Keep code compact - Long scripts are harder to debug in shell context

Caveats

  • No persistent state between run_shell calls (unlike execute_code_sandbox)
  • Longer execution time for complex scripts due to Python interpreter startup
  • Limited debugging - Cannot easily inspect variables between statements
  • Output size limits - Very large outputs may be truncated

When NOT to Use This Fallback

  • If the task specifically requires sandbox isolation for security
  • If you need persistent state across multiple code executions
  • If the code execution is extremely long-running (consider backgrounding)

© HKUDS, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 1 other file in benchmarks/gdpval/skills/sandbox-fallback-python of HKUDS/OpenSpace.

  • SKILL.md
  • .skill_id

Open the folder on GitHubat commit 3827781

Compare with similar skills

Sandbox Fallback Python next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Sandbox Fallback Python compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Sandbox Fallback Python this skillHKUDS/OpenSpace7.7k—~790Automated safety check: PassMIT
MCP Server Builderanthropics/skills180k62 repos~2.3kAutomated safety check: PassApache-2.0
PDF Processinganthropics/skills180k48 repos~2kAutomated safety check: PassProprietary
NotebookLM Research AssistantPleasePrompto/notebooklm-skill7.8k13 repos~2.4kAutomated safety check: NotesMIT
Manim Video Productionbrowser-use/video-use28k6 repos~3kAutomated safety check: PassMIT
Code Review ChecklistshareAI-lab/learn-claude-code78k5 repos~1.1kAutomated safety check: PassMIT

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Works with

Questions about Sandbox Fallback Python

What does Sandbox Fallback Python do?

Fallback to runshell with embedded Python when executecodesandbox fails due to e2b unavailability. Sandbox Fallback Python is an agent skill from HKUDS/OpenSpace.

How do I install Sandbox Fallback Python in Claude Code?

Run `npx skills add HKUDS/OpenSpace --skill sandbox-fallback-python -a claude-code`. Or copy the skill folder (benchmarks/gdpval/skills/sandbox-fallback-python in HKUDS/OpenSpace) into .claude/skills/sandbox-fallback-python in your project. Claude Code loads it when a task matches its description.

How do I install Sandbox Fallback Python in Codex?

Run `npx skills add HKUDS/OpenSpace --skill sandbox-fallback-python -a codex`. Or copy the skill folder (benchmarks/gdpval/skills/sandbox-fallback-python in HKUDS/OpenSpace) into .agents/skills/sandbox-fallback-python in your project. Codex loads it when a task matches its description.

Can I use Sandbox Fallback Python in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add HKUDS/OpenSpace --skill sandbox-fallback-python -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/sandbox-fallback-python, .gemini/skills/sandbox-fallback-python, .github/skills/sandbox-fallback-python and .opencode/skills/sandbox-fallback-python in your project.

What does Sandbox Fallback Python need to run?

Going by SKILL.md and its folder, Sandbox Fallback Python needs the command-line tools its instructions call (python3 and pip). Our summary lists: Python 3.

Does Sandbox Fallback Python access the network?

SKILL.md contains no URLs. Its commands use pip, which can reach the network depending on how they are called. This is read from the text; nothing was executed.

Is Sandbox Fallback Python safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Sandbox Fallback Python use?

Sandbox Fallback Python is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Sandbox Fallback Python use?

About 790 tokens (SKILL.md is roughly 3.2k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Sandbox Fallback Python?

Skills that share tags, products or a category with Sandbox Fallback Python: MCP Server Builder (anthropics/skills, 180k stars), PDF Processing (anthropics/skills, 180k stars), NotebookLM Research Assistant (PleasePrompto/notebooklm-skill, 7.8k stars) and Manim Video Production (browser-use/video-use, 28k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Sandbox Fallback Python?

HKUDS (a GitHub organization) maintains it in HKUDS/OpenSpace, which has 7,743 GitHub stars. The repository holds 199 skills in this directory. The repository was last updated on August 12, 2026.

Source: HKUDS/OpenSpace on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.