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Agent skill

Fallback Code Execution

by HKUDS in HKUDS/OpenSpace

Fallback workflow for running code via file write and shell when sandbox execution fails

MITAuto-check passed

Install Fallback Code Execution

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

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

GitHub CLI
$ gh skill install HKUDS/OpenSpace fallback-code-execution --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/fallback-code-execution .claude/skills/fallback-code-execution && 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
fallback-code-execution
GitHub stars
7.7k
Token cost
~763 tokens
SKILL.md length
356 words
Files
2
Skills in repo
199
Repo updated
First seen
Licence
MIT

At a glance

Fallback workflow for running code via file write and shell when sandbox execution fails

  • Works in 3 steps: Write Script to File → Execute via Shell → Verify Execution
  • SKILL.md covers Overview, Trigger Conditions, Procedure and Best Practices, plus 1 more section
  • Calls python3 and python

What it does

Fallback Code Execution is an agent skill from HKUDS/OpenSpace. Fallback workflow for running code via file write and shell when sandbox execution fails

Its SKILL.md is about 760 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

  • “/fallback-code-execution”

Requirements

  • Python 3

Workflow steps

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

  1. Write Script to File
  2. Execute via Shell
  3. Verify Execution

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
    • python

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

  • Network

    No URLs in SKILL.md.

    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

Fallback Code Execution loads about 763 tokens when it runs. Until then it costs about 28 tokens; SKILL.md has 356 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~28
When it runs · the whole SKILL.md, loaded when a task matches
~763

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). 356 words, ~763 tokens.

Download SKILL.mdSave it as .claude/skills/fallback-code-execution/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.
name
fallback-code-execution
description
Fallback workflow for running code via file write and shell when sandbox execution fails

Fallback Code Execution Workflow

Overview

This skill defines a robust workaround for executing code (specifically Python) when the primary execute_code_sandbox tool fails repeatedly with unknown or transient errors. Instead of continuing to retry the failing tool, the agent switches to a manual file-write and shell-execution pattern.

Trigger Conditions

Activate this workflow when:

  1. execute_code_sandbox fails 2 or more times consecutively for the same logic.
  2. Error messages are generic, unknown, or indicate environment issues rather than syntax errors.
  3. The code logic itself is verified correct but the execution environment is unstable.

Procedure

Step 1: Write Script to File

Use the write_file tool to save the Python script to a specific path in the workspace.

  • Path: Choose a descriptive name ending in .py (e.g., scripts/generate_report.py).
  • Content: Ensure the script includes necessary error handling and print statements for debugging.
  • Dependencies: If the script requires external libraries, ensure a requirements.txt is updated or installed via shell beforehand.

Example:

yaml
tool: write_file
path: workspace/scripts/process_data.py
content: |
  import sys
  # ... script logic ...
  print("Success")
Step 2: Execute via Shell

Use the run_shell tool to execute the script using the system Python interpreter.

  • Command: python3 <path_to_script> or python <path_to_script>.
  • Working Directory: Ensure the shell command runs from the workspace root or the directory containing the script.
  • Capture Output: Store stdout and stderr for verification.

Example:

yaml
tool: run_shell
command: python3 scripts/process_data.py
Show full SKILL.md (150 more words)Show less
Step 3: Verify Execution
  1. Check Exit Code: Ensure the shell command returned exit code 0.
  2. Check Output: Verify expected files were created or expected stdout messages appeared.
  3. Handle Errors: If the shell execution fails, inspect the stderr output. This often provides more detailed tracebacks than the sandbox tool.

Best Practices

  • Absolute Paths: When writing scripts that access files, use absolute paths or resolve paths relative to __file__ to avoid working directory issues.
  • Permissions: Ensure the workspace directory allows file creation and execution.
  • Cleanup: Optionally remove temporary scripts after successful execution if cleanliness is required.
  • Logging: Add explicit print() statements in the Python script to log progress, as shell output capture is sometimes more reliable than sandbox return values.

Example Scenario

Problem: execute_code_sandbox times out while generating a PDF. Solution:

  1. Write generate_pdf.py to workspace/scripts/.
  2. Run python3 workspace/scripts/generate_pdf.py via run_shell.
  3. Confirm output.pdf exists in the workspace.

© 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/fallback-code-execution of HKUDS/OpenSpace.

  • SKILL.md
  • .skill_id

Open the folder on GitHubat commit 3827781

Compare with similar skills

Fallback Code Execution 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.

Fallback Code Execution compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Fallback Code Execution this skillHKUDS/OpenSpace7.7k—~763Automated 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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  • Code Execution Fallback

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  • Code Execution Fallback and Path Anchoring

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Works with

Questions about Fallback Code Execution

What does Fallback Code Execution do?

Fallback workflow for running code via file write and shell when sandbox execution fails. Fallback Code Execution is an agent skill from HKUDS/OpenSpace.

How do I install Fallback Code Execution in Claude Code?

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

How do I install Fallback Code Execution in Codex?

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

Can I use Fallback Code Execution 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 fallback-code-execution -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/fallback-code-execution, .gemini/skills/fallback-code-execution, .github/skills/fallback-code-execution and .opencode/skills/fallback-code-execution in your project.

What does Fallback Code Execution need to run?

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

Does Fallback Code Execution access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Fallback Code Execution 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 Fallback Code Execution use?

Fallback Code Execution 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 Fallback Code Execution use?

About 763 tokens (SKILL.md is roughly 3.1k 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 Fallback Code Execution?

Skills that share tags, products or a category with Fallback Code Execution: 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 Fallback Code Execution?

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.