docs: add CONTRIBUTING guide

Document the process for adding or modifying a skill, frontmatter requirements, style (British English), commit conventions, and the licence under which contributions are accepted.

.gitignore

@@ -1,2 +1,22 @@
 # Local Claude Code configuration (per-machine)
 .claude/
+
+# IDE
+.idea/
+.vscode/
+*.iml
+*.iws
+*.ipr
+.project
+.classpath
+.settings/
+
+# OS
+.DS_Store
+Thumbs.db
+desktop.ini
+
+# Editor backups
+*.swp
+*.swo
+*~

CONTRIBUTING.md

@@ -0,0 +1,61 @@
+# Contributing
+
+Guidelines for adding or modifying a skill in this catalogue.
+
+## Adding a Skill
+
+1. Pick a short, kebab-case name (`my-skill`).
+2. Create a directory and a `SKILL.md` inside it:
+   ```
+   mkdir my-skill
+   ```
+3. Start `SKILL.md` with the required frontmatter:
+   ```yaml
+   ---
+   name: my-skill
+   description: ...
+   ---
+   ```
+4. Open a pull request against `main`.
+
+### Frontmatter
+
+- `name` must match the directory name. Claude Code uses it to identify the skill.
+- `description` controls when the skill is invoked. Be specific: name the file types, project shapes, and user requests that should trigger it. A vague description (for example, "helps with Java") will fire too often and add noise.
+- The body of `SKILL.md` is loaded into the conversation when the skill fires. Keep it dense and self-contained.
+
+## Modifying a Skill
+
+Edit the skill's `SKILL.md` in place. Open a PR. If the change alters the skill's public contract (the `description`, the rules, or the inputs/outputs the skill expects), call it out in the PR description so reviewers can decide whether the change should also trigger a version bump in any catalogue that consumes it.
+
+## Style
+
+- **British English** is the default for all prose, code comments, and commit messages. Use the `british-english` skill to self-review before requesting review.
+- Use sentence case in headings ("Adding a skill", not "Adding A Skill").
+- Code samples should be runnable, or marked clearly when truncated for brevity.
+
+## Commit Messages
+
+Use conventional commits. For this repository:
+
+| Type | When |
+|---|---|
+| `feat` | A new skill, or a new feature within an existing skill |
+| `fix` | A behavioural correction |
+| `docs` | README, CONTRIBUTING, LICENCE, or doc-only edits |
+| `chore` | Tooling, `.gitignore`, build configuration |
+
+See the `commit-message` skill for the full format.
+
+## Review
+
+Reviewers check for:
+
+- Frontmatter correctness and specificity
+- Compliance with any cross-cutting rules (for example, the four-layer architecture in the `spring-boot` skill)
+- British English conformance
+- A concrete example for every non-trivial claim
+
+## Licence
+
+By contributing, you agree that your contributions are licensed under the MIT Licence (see [`LICENCE`](LICENCE)).

LICENCE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Onixbyte
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -5,3 +5,22 @@ This repository stores commonly used skills for Claude Code internally.
 ## Installation
 
 Clone this repository into `~/.claude/skills` with `git clone git@git.onixbyte.com:onixbyte/claude-code-skills ~/.claude/skills`.
+
+## Available Skills
+
+| Skill | Description |
+|---|---|
+| `british-english` | Apply British English spelling and grammar as a global default for files, commits, and documentation when no project-level language override is set. |
+| `commit-message` | Produce conventional-commit messages from the current staged diff, with optional gitmoji support. |
+| `spring-boot` | Conventions for Spring Boot services on Gradle + Java 21 + Spring Boot 3.5: a strict four-layer architecture (Controller → Service → Manager/Client → Mapper/Repository), with an optional Variant layer for multi-implementation strategies. Covers MyBatis + JPA, Spring Validation, global exception handling, TraceId logging, and SpringDoc OpenAPI. |
+
+## Adding a Skill
+
+1. Create a directory named after the skill: `mkdir my-skill/`.
+2. Add a `SKILL.md` inside it, beginning with the required frontmatter (`name`, `description`).
+3. Open a pull request against `main`.
+
+## Repository Hygiene
+
+- Local Claude Code configuration (`.claude/`) is ignored — keep per-machine settings out of version control.
+- Each skill lives in its own top-level directory named exactly as the `name` field in its `SKILL.md`.