codeguard-ocaml

OCaml 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 无专用标记文件 or the target file exists.
2. Probe tools:ocamlformat --version。
3. First do a read-only check:ocamlformat --check .。
4. Classify results as: code violations, missing configuration, missing tools, tool internal errors.
5. Only perform safely fixable items:ocamlformat -i .。
6. Rerun lint, and run the project's existing test/build gates.

You can directly ask:

• "Check this OCaml project, do not modify it first, and give me a classification of lint failures."
• "Only fix OCaml formatting issues; list semantic issues first."
• "Verify OCaml lint, test, and build evidence before committing."

Capability boundaries

✅ Good at handling

1. Based on .ml, .mli and project markers, identify the OCaml workspace.
2. Run ocamlformat --check . and preserve exit codes, scope, and tool versions.
3. Distinguish formatting, static rule, configuration, dependency, and environment failures.
4. Use ocamlformat -i . to handle reversible issues and rescan.
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 project constraints.
2. It must be run from the correct repository or module root directory.
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/raise thresholds to hide real issues.
4. Do not claim "check passed" when tools or configuration are missing.

When to use

• The user requests checking or fixing OCaml code standards.
• AI modified .ml, .mli, and pre-commit verification is needed.
• CI has failures related to ocamlformat --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 one error and there is no project context, first provide 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 V0.5)
File extensions	.ml, .mli
Project marker	No dedicated marker file
Integration config	Follow the repository's existing configuration
Tool preparation	opam install ocamlformat
Probe command	使用命令查找与项目配置检查
lint	ocamlformat --check .
format/fix	ocamlformat -i .
Project-level gate	ocamlformat --check .

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 Follow the repository's existing configuration and the actual commands in 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," not as passing.

Step 4: Run read-only checks

Run ocamlformat --check ., 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	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 the integration or report the prerequisites
Environment	command not found, version conflicts	Report installation/version requirements; do not install silently
Tool internal error	crash, timeout, parser exception	Preserve the original evidence and narrow the reproduction scope

Step 6: Controlled fixes

Prefer to run ocamlformat -i .. Handle only 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 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 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 clearly marked.

Output template

OCaml 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. formatter is not a linter — All-green formatting cannot override static rules or compilation errors.
3. 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} must be replaced with real, authorized paths.
5. Auto-fix 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 casually scan or modify third-party content across the whole repository.

Domain pitfalls and fixes

1. Domain pitfall — The ocamlformat version is part of the formatting contract; different versions may produce large, meaningless diffs.

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. The 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. An exemption is allowed only when the user explicitly accepts it 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 is no rule, 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 we say CI will pass? No. You also need to align the CI's version, environment variables, operating system, and command scope.

Load resources on demand

• When encountering exit codes, failure classification, 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.