GHA-172 Add CLAUDE.md (#82)

Author: nils-werner-sonarsource

CLAUDE.md

@@ -0,0 +1,87 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Repository Overview
+
+This is a collection of reusable GitHub Actions for automating SonarSource analyzer releases. Actions handle Jira integration (tickets, versions, release notes), GitHub releases, cross-repository updates, and Slack notifications.
+
+## Testing
+
+### Run all tests (CI)
+Tests run automatically via GitHub Actions. To trigger manually:
+- Push to `master` runs `.github/workflows/test-all.yml`
+- PRs and pushes to `branch-*` run action-specific test workflows
+
+### Run unit tests locally for a Python action
+```bash
+cd <action-name>
+pip install -r requirements.txt
+pip install pytest pytest-cov
+python -m pytest test_*.py -v --cov=<module_name> --cov-report=term-missing
+```
+
+Example for lock-branch:
+```bash
+cd lock-branch
+pip install -r requirements.txt
+pip install pytest pytest-cov
+python -m pytest test_lock_branch.py test_notify_slack.py test_utils.py -v
+```
+
+### Run a single test
+```bash
+cd <action-name>
+python -m pytest test_<module>.py::TestClassName::test_method_name -v
+```
+
+## Architecture
+
+### Action Types
+- **Python-based** (Jira integration): `create-jira-release-ticket/`, `create-jira-version/`, `release-jira-version/`, `get-jira-release-notes/`, `create-integration-ticket/`, `update-release-ticket-status/`, `lock-branch/`
+- **Bash-based** (GitHub/version operations): `get-release-version/`, `get-jira-version/`, `publish-github-release/`, `check-releasability-status/`, `update-analyzer/`, `update-rule-metadata/`, `notify-slack/`
+
+### Action Structure
+Each action follows this pattern:
+```
+action-name/
+├── action.yml           # Composite action definition
+├── README.md            # Documentation
+├── requirements.txt     # Python deps (if applicable)
+├── <script>.py          # Implementation
+└── test_<script>.py     # pytest unit tests
+```
+
+### Key Patterns
+- All actions use `using: "composite"` (not JavaScript/Docker)
+- Credentials from `SonarSource/vault-action-wrapper@v3`
+- Python actions use Python 3.10
+- Error output via stderr (`eprint()`), values via stdout to `$GITHUB_OUTPUT`
+- Input precedence: explicit input > environment variable > default
+
+### Jira Custom Field IDs
+```python
+customfield_10146  # SHORT_DESCRIPTION
+customfield_10145  # LINK_TO_RELEASE_NOTES
+customfield_10147  # DOCUMENTATION_STATUS
+customfield_11263  # RULE_PROPS_CHANGED
+customfield_11264  # SONARLINT_CHANGELOG
+```
+
+### Version Formats
+- Release version: `X.Y.Z.buildNumber` (e.g., `11.44.2.12345`)
+- Jira version: `X.Y` or `X.Y.Z` (trailing `.0` removed)
+
+## Security
+
+When modifying `action.yml` files, never interpolate user-controlled inputs directly in `run:` blocks. Pass them through environment variables:
+
+```yaml
+# Bad - script injection risk
+run: echo "${{ inputs.branch }}"
+
+# Good - use env vars
+env:
+  INPUT_BRANCH: ${{ inputs.branch }}
+run: echo "$INPUT_BRANCH"
+```