codeguard-elm

Elm Codeguard Gate

Goal: turn "looks fine" into repeatable tool evidence, and honestly distinguish between pass, fail, unable to verify, and planned.

Start in 30 seconds

1. At the repository root, confirm that elm.json or the target file exists.
2. Detect tools:elm-review --version。
3. First do a read-only check:elm-review。
4. Classify results into: code violations, missing configuration, missing tools, tool internal errors.
5. Only perform safe fixes:elm-format --yes。
6. Re-run lint, and execute the project's existing test/build gates.

You can directly propose:

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

Capability boundaries

✅ Good at handling

1. Identify an Elm workspace based on .elm and project markers.
2. Execute elm-review and retain the exit code, scope, and tool version.
3. Distinguish between formatting, static rules, configuration, dependency, and environment failures.
4. Use elm-format --yes to handle reversible issues and re-scan.
5. Report local results separately from CI/build/test evidence.

⚠️ Requires conditions

1. The target tool must already be installed and its version compatible with the project's constraints.
2. It must be executed from the correct repository or module root directory.
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 passing as compilation, testing, 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 problems.
4. Do not claim "check passed" when tools or configuration are missing.

When to use

• The user requests checking or fixing Elm code standards.
• AI has modified .elm, and pre-commit verification is needed.
• CI shows failures related to elm-review .
• It is necessary to determine whether a problem 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, first provide a local explanation and do not claim the whole repository is 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

Project	Current Facts
Status	stable(since Codeguard V0.5)
File Extensions	.elm
Project Markers	elm.json
Integration Configuration	elm.json
Tool Preparation	npm install -g elm-review elm-format
Probe Commands	使用命令查找与项目配置检查
lint	elm-review
format/fix	elm-format --yes
Project-level gate	elm-review

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, first list the modules that will be scanned; guessing based on the current directory is prohibited.

Step 2: Read the project contract

Read elm.json and the actual commands in CI. Repository configuration takes precedence over the examples in this skill; if the two conflict, report the differences first.

Step 3: Probe 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: Perform read-only checks

Run elm-review, recording the command, working directory, exit code, tool version, and the first actionable error.

Step 5: Classify failures

Type	Typical Signals	Handling
Formatting	Indentation, whitespace, import order	Formatter is allowed, then inspect the diff
Static rules	unused, complexity, naming, dangerous APIs	Minimal semantic fixes; batch guessing is prohibited
Configuration	parser/config/schema not found	Fix the integration or report the prerequisites
Environment	command not found, version conflicts	Report installation/version requirements; do not install silently
Tool internal errors	crash, timeout, parser exceptions	Preserve the original evidence and narrow the reproduction scope

Step 6: Controlled fixes

Prioritize running elm-format --yes. 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. Write "passed" only 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 a fix, the original command that triggered the failure must be re-run.
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 takes precedence: 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 explicitly marked.

Output Template

Elm 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 up static rule or compilation errors.
3. The root directory determines the result — Running in the wrong module may miss detection or load the wrong configuration.
4. Placeholders are not literal arguments — {file} and must be replaced with real, authorized paths.
5. Automatic fixes may enlarge the diff — after fixing, review the diff first, then run the regression gates.
6. Generated and vendor directories require an explicit policy — do not casually scan or modify third-party content across the whole repository.

Domain pitfalls and fixes

1. Domain pitfall — elm-review depends on the project's review configuration; if it is not initialized, report that verification is not possible.

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 commands in CI;
5. Whether automatic fixes are allowed.

FAQ

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

Q2: Can I automatically add ignore or suppression? No. Exemptions are allowed only 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 making too many changes at once? Fix in batches by failure category and file, and after each batch rerun the original command and review the diff.

Q6: If it passes locally, can I say CI will pass? No. You also need to align the CI's versions, environment variables, operating system, and command scope.

Load resources as needed

• 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 by scenario examples/; there is no need to load all of them at once.