Agent skill

Leon Coding Agent

by leon-ai in leon-ai/leon

Has Leon's agent investigate, change and verify code in a repository with its file, search and shell tools, staying inside the scope the owner authorized.

MITAuto-check passedDevelopment

Install Leon Coding Agent

skills CLI
$ npx skills add leon-ai/leon --skill coding -a claude-code

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

GitHub CLI
$ gh skill install leon-ai/leon coding --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/leon-ai/leon.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/agent/coding .claude/skills/coding && 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
coding
GitHub stars
18k
Token cost
~1.1k tokens
SKILL.md length
571 words
Files
1
Skills in repo
4
Repo updated
First seen
Licence
MIT

At a glance

Has Leon's agent investigate, change and verify code in a repository with its file, search and shell tools, staying inside the scope the owner authorized.

  • Works in 4 steps: Establish the exact workspace and… → Before editing, discover and read… → Record the workspace, applicable… → …
  • Fixing a bug in a repository with Leon
  • SKILL.md covers Repository and instructions, Investigate and change and Verify and finish
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Leon completes coding tasks directly with its existing agent loop and tools under this skill. Analysis does not count as permission to edit, commit, push or publish, and work goes to another agent only when the owner asks or has a stated preference. When delegation is used, the result must be inspected and verified, because submitting a prompt is not completion.

Before editing, the agent fixes the workspace, reads manifests and nearby code, and finds AGENTS.md files from the repo root down to each target directory, where deeper files win. It checks Git status and leaves unrelated changes and untracked files alone. Investigation uses bounded reads, ripgrep and structural search, and it confirms that symbols exist instead of inventing them. Bugs are reproduced before they are fixed, tests are never weakened to pass, and edits to existing text prefer file.patch with exact context, re-reading after a stale or ambiguous match.

When your agent uses it

  • Fixing a bug in a repository with Leon
  • Making a scoped code change while preserving other uncommitted work
  • Having Leon follow nested AGENTS.md instructions
  • Verifying a change with relevant checks before calling it done

Example prompts

  • “Fix the failing date parser in this repo and show me the test that reproduces it.”
  • “Rename the config option across the project but don't commit anything.”
  • “Investigate why the build fails and tell me what you find, without editing.”

Requirements

  • Leon with its file, search and shell tools

Workflow steps

4 steps, taken from the first numbered list in SKILL.md.

  1. Establish the exact workspace and working directory from the request and live observations. Read relevant manifests and nearby…
  2. Before editing, discover and read applicable AGENTS.md files from the repository root through each target directory. Deeper instructions…
  3. Record the workspace, applicable instruction paths and constraints in the persistent plan. Before editing a new directory, discover its…
  4. Inspect Git status and existing staged/unstaged diffs. Record unrelated changed and untracked files and preserve their content. Do not…

What it can do on your machine

Read from SKILL.md and the folder at commit 2471443. 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

    No scripts in the folder and no shell commands in SKILL.md.

    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

Leon Coding Agent loads about 1.1k tokens when it runs. Until then it costs about 30 tokens; SKILL.md has 571 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~30
When it runs · the whole SKILL.md, loaded when a task matches
~1.1k

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 leon-ai/leon at commit 2471443, republished under its MIT licence (© leon-ai). 571 words, ~1,061 tokens.

Download SKILL.mdSave it as .claude/skills/coding/SKILL.md (or your agent's skills folder).
name
coding
description
Investigate, implement and verify code changes directly in a repository using Leon's file, search and shell tools.
metadata.author
Louis Grenard <louis@getleon.ai>
metadata.version
1.0.0

Coding

Use Leon's existing agent loop and tools to complete coding tasks directly. Respect the owner's requested scope: analysis is not authorization to edit, commit, push or publish. Delegate only when the owner asks or has an applicable preference.

For requested delegation, use the owner's preferred available agent and interface. Pass the repository, task, applicable instructions and authorized scope. Inspect and verify the actual result; submitting a prompt is not completion. If delegation is unavailable, explain briefly and continue directly within the authorized scope.

Repository and instructions

  1. Establish the exact workspace and working directory from the request and live observations. Read relevant manifests and nearby implementations; use existing helpers before adding abstractions.
  2. Before editing, discover and read applicable AGENTS.md files from the repository root through each target directory. Deeper instructions apply only within their directory and take precedence over broader project rules. For a non-Git workspace, use the owner-selected workspace boundary; do not inherit unrelated parent-directory instructions.
  3. Record the workspace, applicable instruction paths and constraints in the persistent plan. Before editing a new directory, discover its nested instructions. After compaction or continuation, reload applicable instruction files before further edits; summaries are not substitutes for their full current content.
  4. Inspect Git status and existing staged/unstaged diffs. Record unrelated changed and untracked files and preserve their content. Do not reset, clean, stage or commit owner work without authorization. Use an isolated worktree when concurrent work or the requested workflow warrants it.

Investigate and change

  • Use bounded file reads, ripgrep and available structural search. Trace definitions and callers; check installed dependencies instead of inventing symbols or APIs. Batch independent discovery calls.
  • For a bug, reproduce the failure with a relevant check before changing the implementation. Inspect existing tests and extend only meaningful coverage. Do not weaken tests to obtain a pass.
  • Prefer file.patch for changes to existing text, using the current read's content hash when available. Supply unique exact context and preserve unrelated changes. On stale or ambiguous matches, re-read and revise the patch rather than repeating it or overwriting from a partial view.
  • Use file.write for new files; overwriting an existing file requires its complete current content. Follow the project's formatting and dependency-management instructions.
  • Use shell.executeCommand for finite commands and project checks, always with the observed workspace cwd. Discover commands from project configuration rather than guessing a package manager.
  • Use shell session functions for dev servers, watchers or interactive programs. Record returned session IDs in the plan, follow output cursors, and verify process status. A started process is not a completed or successful check. Never invent handles, replay a command to recover output, or send secrets through stdin.
Show full SKILL.md (131 more words)Show less

Verify and finish

  1. Run the checks required by project instructions and those relevant to the changed behavior. Inspect actual exit codes and diagnostics. Changes after a successful check make that proof stale; rerun affected checks.
  2. Review the final diff against the original task and initial owner changes. Remove accidental edits without discarding owner work. Verify unrelated staged, unstaged and untracked content remains intact.
  3. Stop command sessions owned by this task unless the owner asked to keep them running. Inspect returned termination status; clean up on failures too.
  4. Report what changed, which checks passed or failed, and any remaining blocker. Do not claim completion from an edit acknowledgement, running process or unavailable check. Suggest a commit message when the repository requires one, but do not commit unless asked.

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

Files

Just SKILL.md in skills/agent/coding of leon-ai/leon.

Open the folder on GitHubat commit 2471443

Compare with similar skills

Leon Coding Agent 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.

Leon Coding Agent compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Leon Coding Agent this skillleon-ai/leon18k—~1.1kAutomated safety check: PassMIT
ReleaseYesterday-AI/paperclip-plugin-company-wizard183—~1.6kAutomated safety check: PassMIT
Optimizeopenplayerjs/openplayerjs649—~1.9kAutomated safety check: PassMIT
ShipAgentSystemLabs/core123—~6.2kAutomated safety check: WarnMIT
Targeted Emergency Bug FixVeryGoodOpenSource/vgv-wingspan108—~1.9kAutomated safety check: PassMIT
Ad ReviewCorridorTech/PoseCap220—~2.4kAutomated safety check: NotesApache-2.0

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Works with

Questions about Leon Coding Agent

What does Leon Coding Agent do?

Has Leon's agent investigate, change and verify code in a repository with its file, search and shell tools, staying inside the scope the owner authorized. Leon completes coding tasks directly with its existing agent loop and tools under this skill. Analysis does not count as permission to edit, commit, push or publish, and work goes to another agent only when the owner asks or has a stated preference.

When should I use Leon Coding Agent?

Leon Coding Agent fits situations like: fixing a bug in a repository with Leon; making a scoped code change while preserving other uncommitted work; having Leon follow nested AGENTS.md instructions; verifying a change with relevant checks before calling it done.

How do I install Leon Coding Agent in Claude Code?

Run `npx skills add leon-ai/leon --skill coding -a claude-code`. Or copy the skill folder (skills/agent/coding in leon-ai/leon) into .claude/skills/coding in your project. Claude Code loads it when a task matches its description.

How do I install Leon Coding Agent in Codex?

Run `npx skills add leon-ai/leon --skill coding -a codex`. Or copy the skill folder (skills/agent/coding in leon-ai/leon) into .agents/skills/coding in your project. Codex loads it when a task matches its description.

Can I use Leon Coding Agent 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 leon-ai/leon --skill coding -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/coding, .gemini/skills/coding, .github/skills/coding and .opencode/skills/coding in your project.

What does Leon Coding Agent need to run?

SKILL.md names no scripts, command-line tools or credentials: Leon Coding Agent is instructions for the agent only. Our summary lists: Leon with its file, search and shell tools.

Does Leon Coding Agent 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 Leon Coding Agent 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 Leon Coding Agent use?

Leon Coding Agent 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 Leon Coding Agent use?

About 1.1k tokens (SKILL.md is roughly 4.2k 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 Leon Coding Agent?

Skills that share tags, products or a category with Leon Coding Agent: Release (Yesterday-AI/paperclip-plugin-company-wizard, 183 stars), Optimize (openplayerjs/openplayerjs, 649 stars), Ship (AgentSystemLabs/core, 123 stars) and Targeted Emergency Bug Fix (VeryGoodOpenSource/vgv-wingspan, 108 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Leon Coding Agent?

leon-ai (a GitHub organization) maintains it in leon-ai/leon, which has 17,557 GitHub stars. The repository holds 4 skills in this directory. The repository was last updated on October 6, 2026.

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