codeguard-python

Python Codeguard Gate

Goal: turn "looks fine" into repeatable tool evidence, and honestly distinguish pass, fail, unverifiable, and planned.

Start in 30 seconds

1. At the repository root, confirm that pyproject.toml`, `setup.py`, `requirements.txt or the target file exists.
2. Probe tools:ruff --version。
3. First do a read-only check:ruff check .。
4. Classify results into: code violations, missing configuration, missing tools, tool internal errors.
5. Only perform safely fixable items:ruff check . --fix。
6. Re-run lint, and run the project's existing test/build gates.

You can directly ask:

• "Check this Python project, don't modify anything yet, and give me a classification of the lint failures."
• "Only fix Python formatting issues; list semantic issues first."
• "Verify Python lint, test, and build evidence before committing."

Capability boundaries

✅ Good at handling

1. Identify the Python workspace based on .py and project markers.
2. Run ruff check . and preserve exit codes, scope, and tool versions.
3. Distinguish formatting, static rule, configuration, dependency, and environment failures.
4. Use ruff check . --fix to handle reversible issues and re-scan.
5. Report local results in layers alongside CI/build/test evidence.

⚠️ Requires conditions

1. The target tool must already be installed and its version compatible with the project constraints.
2. It must be run from the correct repository or module root.
3. If the project has custom configuration, the committed configuration takes precedence.
4. Whether generated code, vendor, and cache directories are scanned must follow repository rules.

❌ Not applicable

1. Do not treat formatter passing as compilation, test, or security audit passing.
2. Do not silently install tools, upgrade dependencies, or modify team rules.
3. Do not use suppress/ignore/raising thresholds to hide real issues.
4. Do not claim "checks passed" when tools or configuration are missing.

When to use

• The user requests checking or fixing Python code style.
• AI modified .py, and pre-commit verification is needed.
• CI shows failures related to ruff check . .
• Need to determine whether an issue can be fixed automatically or must be handled manually.

When not to use

• If the main task is learning language syntax, framework design, or business modeling, use the corresponding language professional skill instead.
• If the main task is dependency vulnerabilities, security audits, or license governance, use a specialized security skill.
• When the user only asks to explain an error and there is no project context, first give a local explanation and do not claim the repository is all green.

Data and security

This skill does not collect, upload, send, or store user code and credentials. By default it only reads local repository configuration and runs local tools; it does not install dependencies over the network, and does not record tokens, passwords, or private source code. Before any automatic fix, inspect the diff first; destructive or large-scale changes must be explicitly confirmed by the user.

Execution Contract

Item	Current Facts
Status	stable(Since Codeguard V0.1)
File Extension	.py
Project Marker	pyproject.toml, setup.py, requirements.txt
Onboarding Configuration	Subject to the repository's existing configuration
Tool Preparation	pip install ruff
Detection Command	使用命令查找与项目配置检查
lint	ruff check .
format/fix	ruff check . --fix
Project-Level Gate	ruff check .

Standard Workflow

Step 1: Determine the True Scope

Confirm the repository root, module roots, generated directories, vendor directories, and user-specified files. For multi-module projects, list the modules to be scanned first; do not guess based on the current directory.

Step 2: Read the Project Contract

Read the actual commands in the repository's existing configuration and CI. The repository configuration takes precedence over the examples in this skill; if the two conflict, report the differences first.

Step 3: Detect Tools and Versions

Run 对应工具 --version. Missing tools, incompatible versions, or configurations that fail to load are all recorded as "unable to verify", not as passed.

Step 4: Run Read-Only Checks

Run ruff check ., recording the command, working directory, exit code, tool version, and the first actionable error.

Step 5: Failure Classification

Type	Typical Signal	Handling
Formatting	Indentation, whitespace, import order	Formatter allowed, then check the diff
Static Rules	unused, complexity, naming, dangerous APIs	Minimal semantic fixes, no bulk guessing
Configuration	parser/config/schema not found	Fix onboarding or report prerequisites
Environment	command not found, version conflicts	Report installation/version requirements, do not install silently
Tool Internal Error	crash, timeout, parser exceptions	Preserve raw evidence, narrow the reproduction scope

Step 6: Controlled Fixes

Prefer running ruff check . --fix. Only handle issues that are certain and reversible; dependency upgrades, rule exemptions, generated files, and business semantic changes must be explained separately.

Step 7: Verification Loop

Re-run the same lint command, then run the project's existing tests and build. Only write "passed" when the command, scope, and exit code are all clear; otherwise write "not run" or "unable to verify".

Rules

1. Re-verify with the Same Command: After fixing, the original command that triggered the failure must be re-run.
2. Layered Evidence: lint, format, compile, test, and security are reported separately.
3. Minimal Changes: Do not refactor along the way, and do not expand style fixes into business rewrites.
4. Configuration First: Do not override the project's existing ignore, dialect, target, or version constraints.
5. No Fabrication: Tools not run, configurations not seen, and platforms not verified must be clearly labeled.

Output Template

Python Codeguard 结果
- 范围：<仓库/模块/文件>
- 工具：<名称与版本>
- 命令：<实际命令>
- 状态：PASS / FAIL / UNVERIFIED / PLANNED
- 发现：<按格式/规则/配置/环境分类>
- 修改：<文件与原因；无修改写 none>
- 复验：<命令、退出码>
- 未验证：<测试/构建/平台差异>

Gotchas

1. Missing tools are not a pass — must output UNVERIFIED and an explicit preparation method.
2. A formatter is not a linter — All-green formatting cannot cover static rules or compilation errors.
3. Root directory determines the result — running in the wrong module may miss issues or load the wrong configuration.
4. Placeholders are not literal arguments — {file} must be replaced with real, authorized paths.
5. Auto-fixes may enlarge the diff — after fixing, review the diff first, then run the regression gate.
6. Generated and vendor directories need an explicit policy — do not scan or modify third-party content across the whole repository at will.

Domain pitfalls and fixes

1. Domain pitfall — Ruff's check --fix and format have different responsibilities; when formatting is needed, both should be run separately.
2. Domain pitfall — first read pyproject.toml 's target-version and per-file-ignores; do not override the project contract with global defaults.

When information is insufficient

Do not just say "please provide more information." First give a safe read-only inspection plan, and list the specific items that still need confirmation:

1. repository/module root directory;
2. target tool and version;
3. project configuration file;
4. authoritative command in CI;
5. whether auto-fixes are allowed.

FAQ

Q1: If the tool is not installed, can we conclude the code is fine? No. The status must be UNVERIFIED。

Q2: Can ignore or suppression be added automatically? No. Exemptions may only be granted when the user explicitly accepts them and the reason is recorded.

Q3: Why does it still fail after formatting? The formatter only covers formatting; static rules, configuration, compilation, and tests still need to be handled separately.

Q4: Should generated code be scanned? By default, follow the repository configuration; when there are no rules, exclude generated/vendor first, then explain to the user.

Q5: How can we avoid changing too much at once? First fix in batches by failure category and file, re-running the original command and reviewing the diff for each batch.

Q6: If it passes locally, can we say CI will pass? No. It is also necessary to align CI's version, environment variables, operating system, and command scope.

Load resources on demand

• When encountering exit codes, failure classifications, or exemption decisions, read references/rules/gate-rules.md。
• When you need to check this language's registry, toolchain, and project configuration, read references/tooling/toolchain.md。
• When you need copyable task examples, read examples/by scenario; there is no need to load all of them at once.