codeguard-elixir

Elixir Codeguard Gate

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

30-Second Start

1. At the repository root, confirm mix.exs or the target file exists.
2. Probe tools:mix --version。
3. First do a read-only check:mix credo --strict。
4. Classify results as: code violations, missing configuration, missing tools, tool internal errors.
5. Only perform safe-to-fix items:mix format。
6. Re-run lint, and execute the project's existing test/build gates.

You can directly ask:

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

Capability Boundaries

✅ Good at handling

1. Based on .ex, .exs and project markers to identify the Elixir workspace.
2. Execute mix credo --strict and retain exit codes, scope, and tool versions.
3. Distinguish formatting, static rules, configuration, dependency, and environment failures.
4. Use mix format to handle reversible issues and re-scan.
5. Report local results and CI/build/test evidence in layers.

⚠️ Requires conditions

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

❌ Not applicable

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 mask real issues.
4. Do not claim "checks passed" when tools or configuration are missing.

When to Use

• The user requests checking or fixing Elixir code standards.
• The AI modified .ex, .exs, and pre-commit verification is needed.
• CI shows failures related to mix credo --strict .
• Need to determine whether an issue can be auto-fixed or must be handled manually.

When Not to Use

• When the main task is learning language syntax, framework design, or business modeling, use the corresponding language professional skill instead.
• When 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 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 automated fix, check the diff first; destructive or large-scale changes must be explicitly confirmed by the user.

Execution Contract

Item	Current Fact
Status	stable(Since Codeguard V0.2)
File Extensions	.ex, .exs
Project Markers	mix.exs
Integration Configuration	mix.exs
Tool Preparation	Project requires credo dependency configuration
Probe Command	使用命令查找与项目配置检查
lint	mix credo --strict
format/fix	mix format
Project-level gate	mix credo --strict

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 to be scanned; do not guess based on the current directory.

Step 2: Read the project contract

Read mix.exs and the actual commands in CI. Repository configuration takes precedence over the examples in this skill; if the two conflict, report the discrepancy first.

Step 3: Probe tools and versions

Run 对应工具 --version. Missing tools, incompatible versions, or failure to load configuration are all recorded as "unable to verify", not as passing.

Step 4: Perform read-only checks

Run mix credo --strict, and record 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	Allow formatter, then check the diff
Static Rules	unused, complexity, naming, dangerous APIs	Minimal semantic fixes; no bulk guessing
Configuration	parser/config/schema not found	Fix integration or report prerequisites
Environment	command not found, version conflict	Report installation/version requirements; do not install silently
Internal tool error	crash, timeout, parser exception	Preserve the original evidence and narrow the reproduction scope

Step 6: Controlled fixes

Prefer running mix format. Only handle clearly reversible issues; 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 style fixes into business rewrites.
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

Elixir 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 — you must output UNVERIFIED and a clear preparation method.
2. formatter is not 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. 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. Project configuration takes precedence — tool defaults must not override rules and version constraints already committed to the repository.

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-fix is 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 I avoid changing too much at once? Fix in batches by failure category and file first, and re-run the original command and review the diff after each batch.

Q6: If it passes locally, can I say CI will pass? No. You also need 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 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 them all at once.