docs: add CONTRIBUTING.md

Document how to report issues, set up a development environment, run the
test suites, follow the StandardJS and Conventional Commits conventions,
and submit pull requests.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: dhensby

CONTRIBUTING.md

@@ -0,0 +1,94 @@
+# Contributing to node-mssql
+
+Thanks for your interest in contributing to `node-mssql`! This project is community-maintained, and contributions of all kinds — bug reports, documentation, and code — are welcome.
+
+This guide covers how to report issues, set up a development environment, and submit changes that fit the project's conventions.
+
+## Reporting Issues
+
+### Security vulnerabilities
+
+**Do not** open public issues for security vulnerabilities. Please follow our [Security Policy](SECURITY.md) and report them privately instead.
+
+### Bugs
+
+Before opening a bug report, please search [existing issues](https://github.com/tediousjs/node-mssql/issues) to avoid duplicates. When you open a new issue, the issue template will ask for the information maintainers need to triage it effectively, including:
+
+- Expected and actual behaviour, with relevant SQL and schema where possible.
+- A minimal, reproducible example.
+- Software versions: Node.js, `mssql`, and SQL Server.
+
+### Feature requests
+
+Feature requests are welcome — please open an issue describing the use case and the problem you are trying to solve, rather than only a proposed implementation.
+
+## Development Setup
+
+1. Fork and clone the repository.
+2. Ensure you are running a supported Node.js version. The project requires **Node.js >= 18.19.0** (see the `engines` field in `package.json`).
+3. Install dependencies:
+
+   ```bash
+   npm install
+   ```
+
+### Running the tests
+
+| Command | Description |
+| ------- | ----------- |
+| `npm test` | Runs the linter (StandardJS) followed by the unit tests. This is the baseline check that must pass. |
+| `npm run lint` | Runs StandardJS only. |
+| `npm run test-unit` | Runs the unit tests only. No database required. |
+| `npm run test-tedious` | Runs the integration tests against a live SQL Server using the `tedious` driver. |
+| `npm run test-msnodesqlv8` | Runs the integration tests using the `msnodesqlv8` driver. |
+| `npm run test-cli` | Runs the CLI tool tests. |
+
+To run a single unit test by name:
+
+```bash
+npx mocha --exit -t 15000 --grep "test name" test/common/unit.js
+```
+
+### Integration tests
+
+The integration tests require a running SQL Server instance configured in `test/.mssql.json` (see `.devcontainer/.mssql.json` for the expected shape). The included [dev container](https://containers.dev/) sets up both Node.js and SQL Server via Docker Compose, which is the easiest way to run the full suite locally.
+
+Unit tests (`npm run test-unit`) do **not** require a database, so you can develop and validate most changes without a SQL Server instance.
+
+## Coding Standards
+
+- **Style:** The project uses [StandardJS](https://standardjs.com/) — no semicolons, 2-space indentation, single quotes. There is no config file or override; run `npm run lint` to check your work, and `npx standard --fix` to auto-fix many issues.
+- **Driver-agnostic design:** Shared, public API lives in `lib/base/`; driver-specific implementations live in `lib/tedious/` and `lib/msnodesqlv8/` and override private methods prefixed with an underscore (e.g. `_poolCreate`, `_executeQuery`).
+- **Dual API:** Async methods should support both Promises and callbacks.
+- **Tests:** Add or update tests for any behavioural change. Unit tests go in `test/common/unit.js`; integration tests are added to the shared factory in `test/common/tests.js` so they run against every driver.
+
+## Commit Messages
+
+Commit messages **must** follow the [Conventional Commits](https://www.conventionalcommits.org/) specification. This is enforced by commitlint, and [semantic-release](https://semantic-release.gitbook.io/) uses these messages to automate versioning and changelog generation — so using the correct type matters.
+
+| Type | When to use it | Release impact |
+| ---- | -------------- | -------------- |
+| `fix` | Bug fixes or behavioural corrections that don't change the public interface | **patch** |
+| `feat` | New backwards-compatible functionality | **minor** |
+| `feat!` (or any type with `!`, or a `BREAKING CHANGE:` footer) | Changes that require consumers to update their code | **major** |
+| `chore` | Dependency updates, tooling, housekeeping | none |
+| `ci` | CI pipeline or workflow configuration changes | none |
+| `docs` | Documentation-only changes | none |
+| `style` | Formatting or stylistic changes that don't affect behaviour | none |
+| `refactor` | Code changes that neither fix a bug nor add a feature | none |
+| `test` | Changes that only touch tests | none |
+
+Only `fix` and `feat` trigger a release. If a change needs to be released but doesn't neatly fit either, choose whichever is most appropriate to ensure a release is created.
+
+## Pull Requests
+
+- **Branch from an up-to-date `master`.** All changes go through a pull request — there are no direct commits to `master`.
+- **Keep commits atomic.** Each commit should be a self-contained, deployable change with linting, commitlint, and tests passing. Don't mix unrelated changes (e.g. a bug fix and a documentation tweak) in one commit.
+- **Keep your branch current by rebasing** onto `master` rather than merging `master` into your branch.
+- **PRs are merged with a merge commit** (no squash or rebase merge), so each commit in your PR is preserved in history. Please keep that history clean.
+- Fill out the pull request template, link any related issues, and update the changelog where applicable.
+- Make sure `npm test` passes before requesting review.
+
+For additional background, see the [Contributing page on the project wiki](https://github.com/tediousjs/node-mssql/wiki/Contributing).
+
+Thanks again for contributing!