codeguard-nim

Nim 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 .nimble or the target file exists.
2. Probe tools:nim --version。
3. Read-only check first:nim check src。
4. Classify the results as: code violations, missing configuration, missing tools, tool internal errors.
5. Only perform safe fixes:nimpretty -r .。
6. Rerun lint, and run the project's existing test/build gates.

Can be proposed directly:

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

Capability Boundaries

✅ Good At Handling

1. Based on .nim and project markers, identify the Nim workspace.
2. Run nim check src and preserve the exit code, scope, and tool version.
3. Distinguish formatting, static rules, configuration, dependency, and environment failures.
4. Use nimpretty -r . to handle reversible issues and rescan.
5. Report local results and CI/build/test evidence in layers.

⚠️ Requires Conditions

1. The target tool must already be installed and its version must be compatible with the project constraints.
2. It must be executed 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.

❌ Out of Scope

1. Do not treat formatter pass as compilation, test, or security audit pass.
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 asks to check or fix Nim code style.
• AI modified .nim, and pre-commit verification is needed.
• CI shows failures related to nim check src .
• 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 auditing, or license governance, use a dedicated security skill.
• When the user only asks to explain one error and there is no project context, provide a local explanation first and do not claim the repository is all green.

Data and Security

This skill does not collect, upload, send, or store user code or credentials. By default, it only reads local repository configuration and runs local tools; it does not install dependencies over the network, and it 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

Project	Current facts
Status	stable(since Codeguard V0.5)
File extensions	.nim
Project markers	.nimble
Integration configuration	Follow the repository's existing configuration
Tool preparation	nimpretty is bundled with Nim
Probe command	使用命令查找与项目配置检查
lint	nim check src
format/fix	nimpretty -r .
Project-level gate	nim check src

Standard Workflow

Step 1: Determine the real scope

Confirm the repository root, module roots, generated directories, vendor directories, and user-specified files. For multi-module projects, first list the modules that will be scanned; never rely on guessing from the current directory.

Step 2: Read the project contract

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

Step 3: Probe tools and versions

Run 对应工具 --version. Missing tools, incompatible versions, or configuration that cannot be loaded are all recorded as "Unable to verify" and are not a pass.

Step 4: Perform read-only checks

Run nim check src, and record the command, working directory, exit code, tool version, and the first actionable error.

Step 5: Failure classification

Type	Typical signals	Handling
Formatting	Indentation, whitespace, import order	Allow the formatter, then check the diff
Static rules	unused, complexity, naming, dangerous APIs	Minimal semantic fixes; no batch guessing
Configuration	parser/config/schema not found	Fix the integration or report prerequisites
Environment	command not found, version conflicts	Report installation/version requirements; do not install silently
Tool internal errors	crash, timeout, parser exception	Preserve the original evidence and narrow the reproduction scope

Step 6: Controlled fixes

Run first nimpretty -r .. 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 "Pass" 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, you must re-run the original command that triggered the failure.
2. Layered evidence: report lint, format, compile, test, and security separately.
3. Minimal changes: do not refactor along the way, and do not expand a style fix into a business rewrite.
4. Configuration first: do not override the project's existing ignore, dialect, target, or version constraints.
5. No fabrication: tools not run, configuration not seen, and platforms not verified must be clearly marked.

Output template

Nim 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. A missing tool is not a pass — you must output UNVERIFIED and a clear 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 detections or load the wrong configuration.
4. Placeholders are not literal arguments — {file} must be replaced with real, authorized paths.
5. Automatic fixes may expand the diff — After fixing, review the diff first, then run the regression gate.
6. Generated and vendor directories require an explicit policy — Do not arbitrarily scan or modify third-party content across the entire repository.

Domain pitfalls and fixes

1. Domain pitfalls — nim check still depend on the project defines and search paths; single-file default context may produce false positives.

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 tools and versions;
3. Project configuration files;
4. The authoritative command in CI;
5. Whether automatic 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 can only be made 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; if there are no rules, exclude generated/vendor first, then explain to the user.

Q5: How can I avoid changing too much at once? First fix in batches by failure category and file, and rerun the original command and review the diff for each batch.

Q6: If it passes locally, can I say CI will pass? No. You also need to align the CI 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 verify this language's registry, toolchain, and project configuration, read references/tooling/toolchain.md。
• When you need copyable task examples, read by scenario examples/, and there is no need to load all of them at once.