Claude Skills by honnibal

claude-skills

Reusable Claude Code slash command skills. To install a skill, copy it to ~/.claude/commands/ (rename from .md.txt to .md).

The skills and parts of the project documentation were produced semi-automatically using Claude Code. You can read more about the general thinking behind these skills on my blog.

Skills

All skills accept an optional argument to scope the work to specific files or directories. If no argument is given, they work through the project or ask you to choose a starting scope.

The skills are set to disable-model-invocation: true by default. This means installing them shouldn't pollute your context. You can change this if you want the model to invoke them automatically.

tighten-types.md.txt

Systematically review Python source files and tighten type annotations. Works through a prioritised checklist: missing class attribute annotations, vague Any types replaced with concrete library types, structured dicts promoted to Pydantic models or TypedDict, @overload signatures for narrowable unions, redundant in-body annotations fixed at the root cause, and style modernisation (Optional[X] → X | None, etc.).

/tighten-types src/mypackage/core.py

contract-docstrings.md.txt

Write docstrings that document each function's contract --- what it requires of callers, what it guarantees, and how it fails. Analyses four dimensions: input invariants (preconditions beyond the type signature), errors raised on violation (explicit checks vs. implicit crashes vs. silent wrong results), errors from external state (filesystem, network, databases), and silenced errors (broad except blocks, .get() defaults, suppress()). Produces a structured Contract: section with Preconditions:, Raises:, and Silences: subsections.

/contract-docstrings src/mypackage/pipeline.py

hypothesis-tests.md.txt

Generate property-based tests using Hypothesis. Reads production code, designs input strategies in tests/strategies.py that model the valid search-space for each function (encoding constraints rather than filtering), then writes minimal, behaviour-focused tests. Tests target core contracts --- roundtrips, idempotence, invariant preservation, equivalence to reference implementations --- rather than structural trivia or reimplementations of the function under test.

/hypothesis-tests src/mypackage/scoring.py

mutation-testing.md.txt

Assess test suite strength by introducing deliberate bugs (mutations) one at a time and checking whether any test catches each one. Mutations are chosen from a catalogue (delete side effects, negate conditions, change boundaries, hardcode returns, remove guards, swap operators, modify defaults, swap argument order). Each mutation is applied, tests are run, and the mutation is reverted. Produces a summary table with mutation score, uncaught gaps, diagnostic quality ratings, and recommended tests. Optionally implements missing tests for survived mutations.

/mutation-testing src/mypackage/

pre-mortem.md.txt

Imagine future bug post-mortems for the codebase. Reads production code and identifies fragile areas --- implicit ordering dependencies, shared mutable state, stringly-typed contracts, baked-in data assumptions, coincidental correctness, non-atomic operations, invisible invariants, load-bearing defaults, implicit resource lifecycles, and version-coupled assumptions. Writes realistic incident reports (severity, cause, why it broke, how it was caught, hardening suggestions) for bugs that haven't happened yet but plausibly could from reasonable future edits. Outputs a PRE-MORTEM.md report.

/pre-mortem src/mypackage/

stub-package.md.txt

Generate a condensed structural overview of a Python package or module --- signatures, imports, class attributes, and docstrings only, with function bodies replaced by .... Uses stub_package.py (included in this repo) to parse source with ast and emit a compact representation. Supports --no-docstrings for a more compact view and --no-private to show only public API.

/stub-package src/mypackage/

try-except.md.txt

Audit try/except blocks for overly broad scope, by-catch risk, and catches of built-in exceptions that should be conditional checks. Evaluates whether try/except is the right mechanism (external state and validation-as-parsing vs. local value checks), whether the try block is minimally scoped, whether the except clause is too broad, and whether the handler masks failure. Tightens each block so the try covers only the operation that can actually raise the expected exception.

/try-except src/mypackage/pipeline.py

Why .md.txt instead of .md?

Skill files are served with a .md.txt extension intentionally. A Claude Code skill is a markdown document that gets injected into the LLM's prompt verbatim. Markdown can contain HTML comments (<!-- ... -->) that are invisible when rendered by GitHub but are still present in the raw text --- and therefore still processed by the model. A malicious skill could embed hidden instructions that you would never see when previewing the file on GitHub.

Skill files are maximum privilege remote code execution. Claude Code operates with broad access to your machine --- your filesystem, your shell, your git credentials, your environment variables. A skill that says "helpful refactoring assistant" in its visible text could contain a hidden HTML comment telling the model to exfiltrate files, install packages, or modify code in ways you didn't ask for.

By shipping files as .md.txt, GitHub will render them as plain text rather than as formatted markdown, allowing you to see the content in full.

Before installing any skill from this repo (or anywhere else):

1. Read the raw file contents. Do not trust a rendered markdown preview.
2. Look for HTML comments, invisible unicode characters, or instructions that don't match the stated purpose.
3. Understand that once installed, the skill's full text is handed to an LLM that can execute arbitrary commands on your behalf.

License

MIT