chore: add copilot instructions

.github/copilot-instructions.md

@@ -0,0 +1,78 @@
+# Copilot Instructions
+
+## Project Overview
+
+This is a GitHub Action (`tediousjs/setup-sqlserver`) that installs SQL Server on Windows-based GitHub Action runners. It's built with TypeScript, compiled with `@vercel/ncc`, and runs on Node.js 24.
+
+## Local Development
+
+Use `nvm` to ensure you're running the correct Node.js version. The required version is pinned in `.nvmrc`:
+
+```sh
+nvm use
+```
+
+## Build, Test & Lint
+
+```sh
+npm run build        # ncc build + auto-generates README usage section from action.yml
+npm run test         # mocha + ts-node (runs all tests)
+npm run test:coverage # tests with nyc coverage
+npm run lint         # eslint across src/, misc/, test/
+npm run lint:fix     # eslint with auto-fix
+```
+
+Run a single test file:
+
+```sh
+npx mocha -r ts-node/register './test/utils.ts'
+```
+
+Run a single test by name:
+
+```sh
+npx mocha -r ts-node/register './test/**/**.ts' --grep 'correctly returns for windows-2019'
+```
+
+The build step (`npm run build`) also runs `npm run docs`, which regenerates the usage section in `README.md` from `action.yml` via `misc/generate-docs.ts`. If you change `action.yml` inputs, rebuild to keep the README in sync.
+
+## Architecture
+
+**Entry point:** `src/main.ts` → calls `install()` from `src/install.ts`, which orchestrates the full flow:
+
+1. Reads action inputs via `gatherInputs()` from `src/utils.ts`
+2. Validates OS compatibility using version config from `src/versions.ts`
+3. Optionally installs SQL Native Client (`src/install-native-client.ts`) and ODBC driver (`src/install-odbc.ts`)
+4. Downloads or cache-hits the SQL Server installer (box+exe or standalone exe)
+5. Optionally downloads cumulative updates
+6. Runs the installer via `@actions/exec`
+7. Waits for the database to be ready (exponential backoff)
+
+**Installer abstraction:** `src/installers/` contains a base `Installer` class and `MsiInstaller` subclass used by the native client and ODBC installations. SQL Server itself uses direct exe/box download logic in `src/utils.ts`.
+
+**Version registry:** `src/versions.ts` defines a `Map<string, VersionConfig>` with download URLs, optional box URLs, update URLs, and OS compatibility constraints for each supported SQL Server version (2008–2022).
+
+**Build output:** `@vercel/ncc` bundles everything into `lib/main/index.js`, which is what `action.yml` references. The `lib/` directory is committed to the repository. **Every commit must include up-to-date build output** — CI checks this by rebuilding and running `git diff-files --quiet`. Always run `npm run build` and commit the resulting changes to `lib/` and `README.md` before pushing.
+
+## Conventions
+
+- **Testing:** Mocha + Chai + Sinon. Tests heavily stub `@actions/*` packages and module-level dependencies using `sinon.stub()`. Each test file mirrors its source file (e.g., `test/install.ts` tests `src/install.ts`).
+- **Commit messages:** Follow [Conventional Commits](https://www.conventionalcommits.org/) enforced by commitlint. Semantic-release uses these to generate automated releases and changelogs, so correct commit types are critical.
+  - `fix` — Bug fixes or behavioural corrections that don't change public interfaces. Triggers a **patch** release.
+  - `feat` — New backwards-compatible functionality (e.g., adding a new input, method, or option without removing anything). Triggers a **minor** release.
+  - `feat!` (or any type with `!`) — Breaking changes where consumers would need to update their code (removed/renamed inputs, changed default behaviour). Triggers a **major** release.
+  - `chore` — Dependency updates, tooling changes, or housekeeping that doesn't affect project code. **Does not trigger a release.**
+  - `ci` — Changes to CI pipelines or workflow configuration. **Does not trigger a release.**
+  - `style` — Refactoring or stylistic changes that do not change functionality. **Does not trigger a release.**
+  - `test` — Changes that only touch test files. **Does not trigger a release.**
+  - Only `fix` and `feat` trigger releases. If a change doesn't neatly fit `fix` or `feat` but still needs to be released, use whichever is most appropriate to ensure a release is created.
+- **Commits and merges:**
+  - Commits should be atomic and ideally deployable in isolation — all tests, linting, and commitlinting should pass on each individual commit.
+  - PRs are merged using a **merge commit** (no squash-merge or rebase-merge). Each commit in the PR history is preserved.
+  - To keep branches up to date with the base branch, **rebase** onto it rather than merging it in.
+  - All changes must go through a **pull request** — no direct commits to master.
+- **Node version:** Pinned to 24 via `.nvmrc`. The action runs using `node24` (set in `action.yml`).
+- **Imports:** Use the `type` keyword for type-only imports (e.g., `import type { Foo } from './bar'`). When importing both types and values from the same module, use a single import with inline `type` (e.g., `import { type Foo, bar } from './baz'`). Imports are ordered alphabetically by module path, grouped as: `node:` built-ins first, then external packages, then local file imports.
+- **ESLint rules:** Trailing commas required on multiline, semicolons required, no variable shadowing. `@typescript-eslint/no-explicit-any` is disabled in test files.
+- **README updates:** The usage block in `README.md` between `<!-- start usage -->` and `<!-- end usage -->` is auto-generated. Edit `action.yml` inputs, not the README directly.
+- **Keeping this file up to date:** If a change affects the architecture, conventions, build process, or any other information documented here, update this file as part of the same PR.

.nvmrc

@@ -0,0 +1 @@
+24

README.md

@@ -7,7 +7,7 @@ This action installs a version of SQL Server on Windows based GitHub Action Runn
 See [action.yml](./action.yml):
 <!-- start usage -->
 ```yaml
-- uses: tediousjs/setup-sqlserver@v2
+- uses: tediousjs/setup-sqlserver@v3
   with:
     # Skip OS checks that will stop installation attempts preemptively.
     # Default: false